path: root/contrib/ntp/ntpd/ntp_io.c

/*
 * ntp_io.c - input/output routines for ntpd.	The socket-opening code
 *		   was shamelessly stolen from ntpd.
 */

#ifdef HAVE_CONFIG_H
# include <config.h>
#endif

#include <stdio.h>
#include <signal.h>
#ifdef HAVE_FNMATCH_H
# include <fnmatch.h>
# if !defined(FNM_CASEFOLD) && defined(FNM_IGNORECASE)
#  define FNM_CASEFOLD FNM_IGNORECASE
# endif
#endif
#ifdef HAVE_SYS_PARAM_H
# include <sys/param.h>
#endif
#ifdef HAVE_SYS_IOCTL_H
# include <sys/ioctl.h>
#endif
#ifdef HAVE_SYS_SOCKIO_H	/* UXPV: SIOC* #defines (Frank Vance <fvance@waii.com>) */
# include <sys/sockio.h>
#endif
#ifdef HAVE_SYS_UIO_H
# include <sys/uio.h>
#endif

#include "ntp_machine.h"
#include "ntpd.h"
#include "ntp_io.h"
#include "iosignal.h"
#include "ntp_lists.h"
#include "ntp_refclock.h"
#include "ntp_stdlib.h"
#include "ntp_worker.h"
#include "ntp_request.h"
#include "ntp_assert.h"
#include "timevalops.h"
#include "timespecops.h"
#include "ntpd-opts.h"
#include "safecast.h"

/* Don't include ISC's version of IPv6 variables and structures */
#define ISC_IPV6_H 1
#include <isc/mem.h>
#include <isc/interfaceiter.h>
#include <isc/netaddr.h>
#include <isc/result.h>
#include <isc/sockaddr.h>

#ifdef SIM
#include "ntpsim.h"
#endif

#ifdef HAS_ROUTING_SOCKET
# include <net/route.h>
# ifdef HAVE_RTNETLINK
#  include <linux/rtnetlink.h>
# endif
#endif

/*
 * setsockopt does not always have the same arg declaration
 * across all platforms. If it's not defined we make it empty
 */

#ifndef SETSOCKOPT_ARG_CAST
#define SETSOCKOPT_ARG_CAST
#endif

extern int listen_to_virtual_ips;

#ifndef IPTOS_DSCP_EF
#define IPTOS_DSCP_EF 0xb8
#endif
int qos = IPTOS_DSCP_EF;	/* QoS RFC3246 */

#ifdef LEAP_SMEAR
/* TODO burnicki: This should be moved to ntp_timer.c, but if we do so
 * we get a linker error. Since we're running out of time before the leap
 * second occurs, we let it here where it just works.
 */
int leap_smear_intv;
#endif

/*
 * NIC rule entry
 */
typedef struct nic_rule_tag nic_rule;

struct nic_rule_tag {
	nic_rule *	next;
	nic_rule_action	action;
	nic_rule_match	match_type;
	char *		if_name;
	sockaddr_u	addr;
	int		prefixlen;
};

/*
 * NIC rule listhead.  Entries are added at the head so that the first
 * match in the list is the last matching rule specified.
 */
nic_rule *nic_rule_list;


#if defined(SO_BINTIME) && defined(SCM_BINTIME) && defined(CMSG_FIRSTHDR)
#  define HAVE_PACKET_TIMESTAMP
#  define HAVE_BINTIME
#  ifdef BINTIME_CTLMSGBUF_SIZE
#   define CMSG_BUFSIZE BINTIME_CTLMSGBUF_SIZE
#  else
#   define CMSG_BUFSIZE  1536 /* moderate default */
#  endif
#elif defined(SO_TIMESTAMPNS) && defined(SCM_TIMESTAMPNS) && defined(CMSG_FIRSTHDR)
#  define HAVE_PACKET_TIMESTAMP
#  define HAVE_TIMESTAMPNS
#  ifdef TIMESTAMPNS_CTLMSGBUF_SIZE
#   define CMSG_BUFSIZE TIMESTAMPNS_CTLMSGBUF_SIZE
#  else
#   define CMSG_BUFSIZE  1536 /* moderate default */
#  endif
#elif defined(SO_TIMESTAMP) && defined(SCM_TIMESTAMP) && defined(CMSG_FIRSTHDR)
#  define HAVE_PACKET_TIMESTAMP
#  define HAVE_TIMESTAMP
#  ifdef TIMESTAMP_CTLMSGBUF_SIZE
#   define CMSG_BUFSIZE TIMESTAMP_CTLMSGBUF_SIZE
#  else
#   define CMSG_BUFSIZE  1536 /* moderate default */
#  endif
#else
/* fill in for old/other timestamp interfaces */
#endif

#if defined(SYS_WINNT)
#include "win32_io.h"
#include <isc/win32os.h>
#endif

/*
 * We do asynchronous input using the SIGIO facility.  A number of
 * recvbuf buffers are preallocated for input.	In the signal
 * handler we poll to see which sockets are ready and read the
 * packets from them into the recvbuf's along with a time stamp and
 * an indication of the source host and the interface it was received
 * through.  This allows us to get as accurate receive time stamps
 * as possible independent of other processing going on.
 *
 * We watch the number of recvbufs available to the signal handler
 * and allocate more when this number drops below the low water
 * mark.  If the signal handler should run out of buffers in the
 * interim it will drop incoming frames, the idea being that it is
 * better to drop a packet than to be inaccurate.
 */


/*
 * Other statistics of possible interest
 */
volatile u_long packets_dropped;	/* total number of packets dropped on reception */
volatile u_long packets_ignored;	/* packets received on wild card interface */
volatile u_long packets_received;	/* total number of packets received */
	 u_long packets_sent;		/* total number of packets sent */
	 u_long packets_notsent;	/* total number of packets which couldn't be sent */

volatile u_long handler_calls;	/* number of calls to interrupt handler */
volatile u_long handler_pkts;	/* number of pkts received by handler */
u_long io_timereset;		/* time counters were reset */

/*
 * Interface stuff
 */
endpt *	any_interface;		/* wildcard ipv4 interface */
endpt *	any6_interface;		/* wildcard ipv6 interface */
endpt *	loopback_interface;	/* loopback ipv4 interface */

isc_boolean_t broadcast_client_enabled;	/* is broadcast client enabled */
u_int sys_ifnum;			/* next .ifnum to assign */
int ninterfaces;			/* Total number of interfaces */

int disable_dynamic_updates;		/* scan interfaces once only */

#ifdef REFCLOCK
/*
 * Refclock stuff.	We keep a chain of structures with data concerning
 * the guys we are doing I/O for.
 */
static	struct refclockio *refio;
#endif /* REFCLOCK */

/*
 * File descriptor masks etc. for call to select
 * Not needed for I/O Completion Ports or anything outside this file
 */
static fd_set activefds;
static int maxactivefd;

/*
 * bit alternating value to detect verified interfaces during an update cycle
 */
static  u_short		sys_interphase = 0;

static endpt *	new_interface(endpt *);
static void	add_interface(endpt *);
static int	update_interfaces(u_short, interface_receiver_t,
				  void *);
static void	remove_interface(endpt *);
static endpt *	create_interface(u_short, endpt *);

static int	is_wildcard_addr	(const sockaddr_u *);

/*
 * Multicast functions
 */
static	isc_boolean_t	addr_ismulticast	(sockaddr_u *);
static	isc_boolean_t	is_anycast		(sockaddr_u *,
						 const char *);

/*
 * Not all platforms support multicast
 */
#ifdef MCAST
static	isc_boolean_t	socket_multicast_enable	(endpt *, sockaddr_u *);
static	isc_boolean_t	socket_multicast_disable(endpt *, sockaddr_u *);
#endif

#ifdef DEBUG
static void interface_dump	(const endpt *);
static void sockaddr_dump	(const sockaddr_u *);
static void print_interface	(const endpt *, const char *, const char *);
#define DPRINT_INTERFACE(level, args) do { if (debug >= (level)) { print_interface args; } } while (0)
#else
#define DPRINT_INTERFACE(level, args) do {} while (0)
#endif

typedef struct vsock vsock_t;
enum desc_type { FD_TYPE_SOCKET, FD_TYPE_FILE };

struct vsock {
	vsock_t	*	link;
	SOCKET		fd;
	enum desc_type	type;
};

vsock_t	*fd_list;

#if !defined(HAVE_IO_COMPLETION_PORT) && defined(HAS_ROUTING_SOCKET)
/*
 * async notification processing (e. g. routing sockets)
 */
/*
 * support for receiving data on fd that is not a refclock or a socket
 * like e. g. routing sockets
 */
struct asyncio_reader {
	struct asyncio_reader *link;		    /* the list this is being kept in */
	SOCKET fd;				    /* fd to be read */
	void  *data;				    /* possibly local data */
	void (*receiver)(struct asyncio_reader *);  /* input handler */
};

struct asyncio_reader *asyncio_reader_list;

static void delete_asyncio_reader (struct asyncio_reader *);
static struct asyncio_reader *new_asyncio_reader (void);
static void add_asyncio_reader (struct asyncio_reader *, enum desc_type);
static void remove_asyncio_reader (struct asyncio_reader *);

#endif /* !defined(HAVE_IO_COMPLETION_PORT) && defined(HAS_ROUTING_SOCKET) */

static void init_async_notifications (void);

static	int	addr_eqprefix	(const sockaddr_u *, const sockaddr_u *,
				 int);
static int	addr_samesubnet	(const sockaddr_u *, const sockaddr_u *,
				 const sockaddr_u *, const sockaddr_u *);
static	int	create_sockets	(u_short);
static	SOCKET	open_socket	(sockaddr_u *, int, int, endpt *);
static	void	set_reuseaddr	(int);
static	isc_boolean_t	socket_broadcast_enable	 (struct interface *, SOCKET, sockaddr_u *);

#if !defined(HAVE_IO_COMPLETION_PORT) && !defined(HAVE_SIGNALED_IO)
static	char *	fdbits		(int, const fd_set *);
#endif
#ifdef  OS_MISSES_SPECIFIC_ROUTE_UPDATES
static	isc_boolean_t	socket_broadcast_disable (struct interface *, sockaddr_u *);
#endif

typedef struct remaddr remaddr_t;

struct remaddr {
	remaddr_t *		link;
	sockaddr_u		addr;
	endpt *			ep;
};

remaddr_t *	remoteaddr_list;
endpt *		ep_list;	/* complete endpt list */
endpt *		mc4_list;	/* IPv4 mcast-capable unicast endpts */
endpt *		mc6_list;	/* IPv6 mcast-capable unicast endpts */

static endpt *	wildipv4;
static endpt *	wildipv6;

#ifdef SYS_WINNT
int accept_wildcard_if_for_winnt;
#else
const int accept_wildcard_if_for_winnt = FALSE;
#endif

static void	add_fd_to_list		(SOCKET, enum desc_type);
static endpt *	find_addr_in_list	(sockaddr_u *);
static endpt *	find_flagged_addr_in_list(sockaddr_u *, u_int32);
static void	delete_addr_from_list	(sockaddr_u *);
static void	delete_interface_from_list(endpt *);
static void	close_and_delete_fd_from_list(SOCKET);
static void	add_addr_to_list	(sockaddr_u *, endpt *);
static void	create_wildcards	(u_short);
static endpt *	findlocalinterface	(sockaddr_u *, int, int);
static endpt *	findclosestinterface	(sockaddr_u *, int);
#ifdef DEBUG
static const char *	action_text	(nic_rule_action);
#endif
static nic_rule_action	interface_action(char *, sockaddr_u *, u_int32);
static void		convert_isc_if	(isc_interface_t *,
					 endpt *, u_short);
static void		calc_addr_distance(sockaddr_u *,
					   const sockaddr_u *,
					   const sockaddr_u *);
static int		cmp_addr_distance(const sockaddr_u *,
					  const sockaddr_u *);

/*
 * Routines to read the ntp packets
 */
#if !defined(HAVE_IO_COMPLETION_PORT)
static inline int	read_network_packet	(SOCKET, struct interface *, l_fp);
static void		ntpd_addremove_io_fd	(int, int, int);
static void 		input_handler_scan	(const l_fp*, const fd_set*);
static int/*BOOL*/	sanitize_fdset		(int errc);
#ifdef REFCLOCK
static inline int	read_refclock_packet	(SOCKET, struct refclockio *, l_fp);
#endif
#ifdef HAVE_SIGNALED_IO
static void 		input_handler		(l_fp*);
#endif
#endif


#ifndef HAVE_IO_COMPLETION_PORT
void
maintain_activefds(
	int fd,
	int closing
	)
{
	int i;

	if (fd < 0 || fd >= FD_SETSIZE) {
		msyslog(LOG_ERR,
			"Too many sockets in use, FD_SETSIZE %d exceeded by fd %d",
			FD_SETSIZE, fd);
		exit(1);
	}

	if (!closing) {
		FD_SET(fd, &activefds);
		maxactivefd = max(fd, maxactivefd);
	} else {
		FD_CLR(fd, &activefds);
		if (maxactivefd && fd == maxactivefd) {
			for (i = maxactivefd - 1; i >= 0; i--)
				if (FD_ISSET(i, &activefds)) {
					maxactivefd = i;
					break;
				}
			INSIST(fd != maxactivefd);
		}
	}
}
#endif	/* !HAVE_IO_COMPLETION_PORT */


#ifdef DEBUG_TIMING
/*
 * collect timing information for various processing
 * paths. currently we only pass them on to the file
 * for later processing. this could also do histogram
 * based analysis in other to reduce the load (and skew)
 * dur to the file output
 */
void
collect_timing(struct recvbuf *rb, const char *tag, int count, l_fp *dts)
{
	char buf[256];

	snprintf(buf, sizeof(buf), "%s %d %s %s",
		 (rb != NULL)
		     ? ((rb->dstadr != NULL)
			    ? stoa(&rb->recv_srcadr)
			    : "-REFCLOCK-")
		     : "-",
		 count, lfptoa(dts, 9), tag);
	record_timing_stats(buf);
}
#endif

/*
 * About dynamic interfaces, sockets, reception and more...
 *
 * the code solves following tasks:
 *
 *   - keep a current list of active interfaces in order
 *     to bind to to the interface address on NTP_PORT so that
 *     all wild and specific bindings for NTP_PORT are taken by ntpd
 *     to avoid other daemons messing with the time or sockets.
 *   - all interfaces keep a list of peers that are referencing
 *     the interface in order to quickly re-assign the peers to
 *     new interface in case an interface is deleted (=> gone from system or
 *     down)
 *   - have a preconfigured socket ready with the right local address
 *     for transmission and reception
 *   - have an address list for all destination addresses used within ntpd
 *     to find the "right" preconfigured socket.
 *   - facilitate updating the internal interface list with respect to
 *     the current kernel state
 *
 * special issues:
 *
 *   - mapping of multicast addresses to the interface affected is not always
 *     one to one - especially on hosts with multiple interfaces
 *     the code here currently allocates a separate interface entry for those
 *     multicast addresses
 *     iff it is able to bind to a *new* socket with the multicast address (flags |= MCASTIF)
 *     in case of failure the multicast address is bound to an existing interface.
 *   - on some systems it is perfectly legal to assign the same address to
 *     multiple interfaces. Therefore this code does not keep a list of interfaces
 *     but a list of interfaces that represent a unique address as determined by the kernel
 *     by the procedure in findlocalinterface. Thus it is perfectly legal to see only
 *     one representative of a group of real interfaces if they share the same address.
 *
 * Frank Kardel 20050910
 */

/*
 * init_io - initialize I/O module.
 */
void
init_io(void)
{
	/* Init buffer free list and stat counters */
	init_recvbuff(RECV_INIT);
	/* update interface every 5 minutes as default */
	interface_interval = 300;

#ifdef WORK_PIPE
	addremove_io_fd = &ntpd_addremove_io_fd;
#endif

#if defined(SYS_WINNT)
	init_io_completion_port();
#elif defined(HAVE_SIGNALED_IO)
	(void) set_signal(input_handler);
#endif
}


static void
ntpd_addremove_io_fd(
	int	fd,
	int	is_pipe,
	int	remove_it
	)
{
	UNUSED_ARG(is_pipe);

#ifdef HAVE_SIGNALED_IO
	if (!remove_it)
		init_socket_sig(fd);
#endif /* not HAVE_SIGNALED_IO */

	maintain_activefds(fd, remove_it);
}


/*
 * io_open_sockets - call socket creation routine
 */
void
io_open_sockets(void)
{
	static int already_opened;

	if (already_opened || HAVE_OPT( SAVECONFIGQUIT ))
		return;

	already_opened = 1;

	/*
	 * Create the sockets
	 */
	BLOCKIO();
	create_sockets(NTP_PORT);
	UNBLOCKIO();

	init_async_notifications();

	DPRINTF(3, ("io_open_sockets: maxactivefd %d\n", maxactivefd));
}


#ifdef DEBUG
/*
 * function to dump the contents of the interface structure
 * for debugging use only.
 * We face a dilemma here -- sockets are FDs under POSIX and
 * actually HANDLES under Windows. So we use '%lld' as format
 * and cast the value to 'long long'; this should not hurt
 * with UNIX-like systems and does not truncate values on Win64.
 */
void
interface_dump(const endpt *itf)
{
	printf("Dumping interface: %p\n", itf);
	printf("fd = %lld\n", (long long)itf->fd);
	printf("bfd = %lld\n", (long long)itf->bfd);
	printf("sin = %s,\n", stoa(&itf->sin));
	sockaddr_dump(&itf->sin);
	printf("bcast = %s,\n", stoa(&itf->bcast));
	sockaddr_dump(&itf->bcast);
	printf("mask = %s,\n", stoa(&itf->mask));
	sockaddr_dump(&itf->mask);
	printf("name = %s\n", itf->name);
	printf("flags = 0x%08x\n", itf->flags);
	printf("last_ttl = %d\n", itf->last_ttl);
	printf("addr_refid = %08x\n", itf->addr_refid);
	printf("num_mcast = %d\n", itf->num_mcast);
	printf("received = %ld\n", itf->received);
	printf("sent = %ld\n", itf->sent);
	printf("notsent = %ld\n", itf->notsent);
	printf("ifindex = %u\n", itf->ifindex);
	printf("peercnt = %u\n", itf->peercnt);
	printf("phase = %u\n", itf->phase);
}

/*
 * sockaddr_dump - hex dump the start of a sockaddr_u
 */
static void
sockaddr_dump(const sockaddr_u *psau)
{
	/* Limit the size of the sockaddr_in6 hex dump */
	const int maxsize = min(32, sizeof(psau->sa6));
	const u_char *	cp;
	int		i;

	/* XXX: Should we limit maxsize based on psau->saX.sin_family? */
	cp = (const void *)&psau->sa6;

	for(i = 0; i < maxsize; i++) {
		printf("%02x", *cp++);
		if (!((i + 1) % 4))
			printf(" ");
	}
	printf("\n");
}

/*
 * print_interface - helper to output debug information
 */
static void
print_interface(const endpt *iface, const char *pfx, const char *sfx)
{
	printf("%sinterface #%d: fd=%lld, bfd=%lld, name=%s, flags=0x%x, ifindex=%u, sin=%s",
	       pfx,
	       iface->ifnum,
	       (long long)iface->fd,
	       (long long)iface->bfd,
	       iface->name,
	       iface->flags,
	       iface->ifindex,
	       stoa(&iface->sin));
	if (AF_INET == iface->family) {
		if (iface->flags & INT_BROADCAST)
			printf(", bcast=%s", stoa(&iface->bcast));
		printf(", mask=%s", stoa(&iface->mask));
	}
	printf(", %s:%s",
	       (iface->ignore_packets)
		   ? "Disabled"
		   : "Enabled",
	       sfx);
	if (debug > 4)	/* in-depth debugging only */
		interface_dump(iface);
}
#endif

#if !defined(HAVE_IO_COMPLETION_PORT) && defined(HAS_ROUTING_SOCKET)
/*
 * create an asyncio_reader structure
 */
static struct asyncio_reader *
new_asyncio_reader(void)
{
	struct asyncio_reader *reader;

	reader = emalloc_zero(sizeof(*reader));
	reader->fd = INVALID_SOCKET;

	return reader;
}

/*
 * delete a reader
 */
static void
delete_asyncio_reader(
	struct asyncio_reader *reader
	)
{
	free(reader);
}

/*
 * add asynchio_reader
 */
static void
add_asyncio_reader(
	struct asyncio_reader *	reader,
	enum desc_type		type)
{
	LINK_SLIST(asyncio_reader_list, reader, link);
	add_fd_to_list(reader->fd, type);
}

/*
 * remove asynchio_reader
 */
static void
remove_asyncio_reader(
	struct asyncio_reader *reader
	)
{
	struct asyncio_reader *unlinked;

	UNLINK_SLIST(unlinked, asyncio_reader_list, reader, link,
	    struct asyncio_reader);

	if (reader->fd != INVALID_SOCKET)
		close_and_delete_fd_from_list(reader->fd);

	reader->fd = INVALID_SOCKET;
}
#endif /* !defined(HAVE_IO_COMPLETION_PORT) && defined(HAS_ROUTING_SOCKET) */


/* compare two sockaddr prefixes */
static int
addr_eqprefix(
	const sockaddr_u *	a,
	const sockaddr_u *	b,
	int			prefixlen
	)
{
	isc_netaddr_t		isc_a;
	isc_netaddr_t		isc_b;
	isc_sockaddr_t		isc_sa;

	ZERO(isc_sa);
	memcpy(&isc_sa.type, a, min(sizeof(isc_sa.type), sizeof(*a)));
	isc_netaddr_fromsockaddr(&isc_a, &isc_sa);

	ZERO(isc_sa);
	memcpy(&isc_sa.type, b, min(sizeof(isc_sa.type), sizeof(*b)));
	isc_netaddr_fromsockaddr(&isc_b, &isc_sa);

	return (int)isc_netaddr_eqprefix(&isc_a, &isc_b,
					 (u_int)prefixlen);
}


static int
addr_samesubnet(
	const sockaddr_u *	a,
	const sockaddr_u *	a_mask,
	const sockaddr_u *	b,
	const sockaddr_u *	b_mask
	)
{
	const u_int32 *	pa;
	const u_int32 *	pa_limit;
	const u_int32 *	pb;
	const u_int32 *	pm;
	size_t		loops;

	REQUIRE(AF(a) == AF(a_mask));
	REQUIRE(AF(b) == AF(b_mask));
	/*
	 * With address and mask families verified to match, comparing
	 * the masks also validates the address's families match.
	 */
	if (!SOCK_EQ(a_mask, b_mask))
		return FALSE;

	if (IS_IPV6(a)) {
		loops = sizeof(NSRCADR6(a)) / sizeof(*pa);
		pa = (const void *)&NSRCADR6(a);
		pb = (const void *)&NSRCADR6(b);
		pm = (const void *)&NSRCADR6(a_mask);
	} else {
		loops = sizeof(NSRCADR(a)) / sizeof(*pa);
		pa = (const void *)&NSRCADR(a);
		pb = (const void *)&NSRCADR(b);
		pm = (const void *)&NSRCADR(a_mask);
	}
	for (pa_limit = pa + loops; pa < pa_limit; pa++, pb++, pm++)
		if ((*pa & *pm) != (*pb & *pm))
			return FALSE;

	return TRUE;
}


/*
 * interface list enumerator - visitor pattern
 */
void
interface_enumerate(
	interface_receiver_t	receiver,
	void *			data
	)
{
	interface_info_t ifi;

	ifi.action = IFS_EXISTS;
	for (ifi.ep = ep_list; ifi.ep != NULL; ifi.ep = ifi.ep->elink)
		(*receiver)(data, &ifi);
}

/*
 * do standard initialization of interface structure
 */
static void
init_interface(
	endpt *ep
	)
{
	ZERO(*ep);
	ep->fd = INVALID_SOCKET;
	ep->bfd = INVALID_SOCKET;
	ep->phase = sys_interphase;
}


/*
 * create new interface structure initialize from
 * template structure or via standard initialization
 * function
 */
static struct interface *
new_interface(
	struct interface *interface
	)
{
	struct interface *	iface;

	iface = emalloc(sizeof(*iface));

	if (NULL == interface)
		init_interface(iface);
	else				/* use the template */
		memcpy(iface, interface, sizeof(*iface));

	/* count every new instance of an interface in the system */
	iface->ifnum = sys_ifnum++;
	iface->starttime = current_time;

#   ifdef HAVE_IO_COMPLETION_PORT
	if (!io_completion_port_add_interface(iface)) {
		msyslog(LOG_EMERG, "cannot register interface with IO engine -- will exit now");
		exit(1);
	}
#   endif
	return iface;
}


/*
 * return interface storage into free memory pool
 */
static void
delete_interface(
	endpt *ep
	)
{
#    ifdef HAVE_IO_COMPLETION_PORT
	io_completion_port_remove_interface(ep);
#    endif
	free(ep);
}


/*
 * link interface into list of known interfaces
 */
static void
add_interface(
	endpt *	ep
	)
{
	endpt **	pmclisthead;
	endpt *		scan;
	endpt *		scan_next;
	endpt *		unlinked;
	sockaddr_u *	addr;
	int		ep_local;
	int		scan_local;
	int		same_subnet;
	int		ep_univ_iid;	/* iface ID from MAC address */
	int		scan_univ_iid;	/* see RFC 4291 */
	int		ep_privacy;	/* random local iface ID */
	int		scan_privacy;	/* see RFC 4941 */
	int		rc;

	/* Calculate the refid */
	ep->addr_refid = addr2refid(&ep->sin);
	/* link at tail so ntpdc -c ifstats index increases each row */
	LINK_TAIL_SLIST(ep_list, ep, elink, endpt);
	ninterfaces++;
#ifdef MCAST
	/* the rest is for enabled multicast-capable addresses only */
	if (ep->ignore_packets || !(INT_MULTICAST & ep->flags) ||
	    INT_LOOPBACK & ep->flags)
		return;
# ifndef INCLUDE_IPV6_MULTICAST_SUPPORT
	if (AF_INET6 == ep->family)
		return;
# endif
	pmclisthead = (AF_INET == ep->family)
			 ? &mc4_list
			 : &mc6_list;

	if (AF_INET6 == ep->family) {
		ep_local =
		    IN6_IS_ADDR_LINKLOCAL(PSOCK_ADDR6(&ep->sin)) ||
		    IN6_IS_ADDR_SITELOCAL(PSOCK_ADDR6(&ep->sin));
		ep_univ_iid = IS_IID_UNIV(&ep->sin);
		ep_privacy = !!(INT_PRIVACY & ep->flags);
	} else {
		ep_local = FALSE;
		ep_univ_iid = FALSE;
		ep_privacy = FALSE;
	}
	DPRINTF(4, ("add_interface mcast-capable %s%s%s%s\n",
		    stoa(&ep->sin),
		    (ep_local) ? " link/scope-local" : "",
		    (ep_univ_iid) ? " univ-IID" : "",
		    (ep_privacy) ? " privacy" : ""));
	/*
	 * If we have multiple local addresses on the same network
	 * interface, and some are link- or site-local, do not multicast
	 * out from the link-/site-local addresses by default, to avoid
	 * duplicate manycastclient associations between v6 peers using
	 * link-local and global addresses.  link-local can still be
	 * chosen using "nic ignore myv6globalprefix::/64".
	 * Similarly, if we have multiple global addresses from the same
	 * prefix on the same network interface, multicast from one,
	 * preferring EUI-64, then static, then least RFC 4941 privacy
	 * addresses.
	 */
	for (scan = *pmclisthead; scan != NULL; scan = scan_next) {
		scan_next = scan->mclink;
		if (ep->family != scan->family)
			continue;
		if (strcmp(ep->name, scan->name))
			continue;
		same_subnet = addr_samesubnet(&ep->sin, &ep->mask,
					      &scan->sin, &scan->mask);
		if (AF_INET6 == ep->family) {
			addr = &scan->sin;
			scan_local =
			    IN6_IS_ADDR_LINKLOCAL(PSOCK_ADDR6(addr)) ||
			    IN6_IS_ADDR_SITELOCAL(PSOCK_ADDR6(addr));
			scan_univ_iid = IS_IID_UNIV(addr);
			scan_privacy = !!(INT_PRIVACY & scan->flags);
		} else {
			scan_local = FALSE;
			scan_univ_iid = FALSE;
			scan_privacy = FALSE;
		}
		DPRINTF(4, ("add_interface mcast-capable scan %s%s%s%s\n",
			    stoa(&scan->sin),
			    (scan_local) ? " link/scope-local" : "",
			    (scan_univ_iid) ? " univ-IID" : "",
			    (scan_privacy) ? " privacy" : ""));
		if ((ep_local && !scan_local) || (same_subnet &&
		    ((ep_privacy && !scan_privacy) ||
		     (!ep_univ_iid && scan_univ_iid)))) {
			DPRINTF(4, ("did not add %s to %s of IPv6 multicast-capable list which already has %s\n",
				stoa(&ep->sin),
				(ep_local)
				    ? "tail"
				    : "head",
				stoa(&scan->sin)));
			return;
		}
		if ((scan_local && !ep_local) || (same_subnet &&
		    ((scan_privacy && !ep_privacy) ||
		     (!scan_univ_iid && ep_univ_iid)))) {
			UNLINK_SLIST(unlinked, *pmclisthead,
				     scan, mclink, endpt);
			DPRINTF(4, ("%s %s from IPv6 multicast-capable list to add %s\n",
				(unlinked != scan)
				    ? "Failed to remove"
				    : "removed",
				stoa(&scan->sin), stoa(&ep->sin)));
		}
	}
	/*
	 * Add link/site local at the tail of the multicast-
	 * capable unicast interfaces list, so that ntpd will
	 * send from global addresses before link-/site-local
	 * ones.
	 */
	if (ep_local)
		LINK_TAIL_SLIST(*pmclisthead, ep, mclink, endpt);
	else
		LINK_SLIST(*pmclisthead, ep, mclink);
	DPRINTF(4, ("added %s to %s of IPv%s multicast-capable unicast local address list\n",
		stoa(&ep->sin),
		(ep_local)
		    ? "tail"
		    : "head",
		(AF_INET == ep->family)
		    ? "4"
		    : "6"));

	if (INVALID_SOCKET == ep->fd)
		return;

	/*
	 * select the local address from which to send to multicast.
	 */
	switch (AF(&ep->sin)) {

	case AF_INET :
		rc = setsockopt(ep->fd, IPPROTO_IP,
				IP_MULTICAST_IF,
				(void *)&NSRCADR(&ep->sin),
				sizeof(NSRCADR(&ep->sin)));
		if (rc)
			msyslog(LOG_ERR,
				"setsockopt IP_MULTICAST_IF %s fails: %m",
				stoa(&ep->sin));
		break;

# ifdef INCLUDE_IPV6_MULTICAST_SUPPORT
	case AF_INET6 :
		rc = setsockopt(ep->fd, IPPROTO_IPV6,
				 IPV6_MULTICAST_IF,
				 (void *)&ep->ifindex,
				 sizeof(ep->ifindex));
		/* do not complain if bound addr scope is ifindex */
		if (rc && ep->ifindex != SCOPE(&ep->sin))
			msyslog(LOG_ERR,
				"setsockopt IPV6_MULTICAST_IF %u for %s fails: %m",
				ep->ifindex, stoa(&ep->sin));
		break;
# endif
	}
#endif	/* MCAST */
}


/*
 * remove interface from known interface list and clean up
 * associated resources
 */
static void
remove_interface(
	endpt *	ep
	)
{
	endpt *		unlinked;
	endpt **	pmclisthead;
	sockaddr_u	resmask;

	UNLINK_SLIST(unlinked, ep_list, ep, elink, endpt);
	if (!ep->ignore_packets && INT_MULTICAST & ep->flags) {
		pmclisthead = (AF_INET == ep->family)
				 ? &mc4_list
				 : &mc6_list;
		UNLINK_SLIST(unlinked, *pmclisthead, ep, mclink, endpt);
		DPRINTF(4, ("%s %s IPv%s multicast-capable unicast local address list\n",
			stoa(&ep->sin),
			(unlinked != NULL)
			    ? "removed from"
			    : "not found on",
			(AF_INET == ep->family)
			    ? "4"
			    : "6"));
	}
	delete_interface_from_list(ep);

	if (ep->fd != INVALID_SOCKET) {
		msyslog(LOG_INFO,
			"Deleting interface #%d %s, %s#%d, interface stats: received=%ld, sent=%ld, dropped=%ld, active_time=%ld secs",
			ep->ifnum,
			ep->name,
			stoa(&ep->sin),
			SRCPORT(&ep->sin),
			ep->received,
			ep->sent,
			ep->notsent,
			current_time - ep->starttime);
#	    ifdef HAVE_IO_COMPLETION_PORT
		io_completion_port_remove_socket(ep->fd, ep);
#	    endif
		close_and_delete_fd_from_list(ep->fd);
		ep->fd = INVALID_SOCKET;
	}

	if (ep->bfd != INVALID_SOCKET) {
		msyslog(LOG_INFO,
			"stop listening for broadcasts to %s on interface #%d %s",
			stoa(&ep->bcast), ep->ifnum, ep->name);
#	    ifdef HAVE_IO_COMPLETION_PORT
		io_completion_port_remove_socket(ep->bfd, ep);
#	    endif
		close_and_delete_fd_from_list(ep->bfd);
		ep->bfd = INVALID_SOCKET;
	}
#   ifdef HAVE_IO_COMPLETION_PORT
	io_completion_port_remove_interface(ep);
#   endif

	ninterfaces--;
	mon_clearinterface(ep);

	/* remove restrict interface entry */
	SET_HOSTMASK(&resmask, AF(&ep->sin));
	hack_restrict(RESTRICT_REMOVEIF, &ep->sin, &resmask,
		      RESM_NTPONLY | RESM_INTERFACE, RES_IGNORE, 0);
}


static void
log_listen_address(
	endpt *	ep
	)
{
	msyslog(LOG_INFO, "%s on %d %s %s",
		(ep->ignore_packets)
		    ? "Listen and drop"
		    : "Listen normally",
		ep->ifnum,
		ep->name,
		sptoa(&ep->sin));
}


static void
create_wildcards(
	u_short	port
	)
{
	int			v4wild;
#ifdef INCLUDE_IPV6_SUPPORT
	int			v6wild;
#endif
	sockaddr_u		wildaddr;
	nic_rule_action		action;
	struct interface *	wildif;

	/*
	 * silence "potentially uninitialized" warnings from VC9
	 * failing to follow the logic.  Ideally action could remain
	 * uninitialized, and the memset be the first statement under
	 * the first if (v4wild).
	 */
	action = ACTION_LISTEN;
	ZERO(wildaddr);

#ifdef INCLUDE_IPV6_SUPPORT
	/*
	 * create pseudo-interface with wildcard IPv6 address
	 */
	v6wild = ipv6_works;
	if (v6wild) {
		/* set wildaddr to the v6 wildcard address :: */
		ZERO(wildaddr);
		AF(&wildaddr) = AF_INET6;
		SET_ADDR6N(&wildaddr, in6addr_any);
		SET_PORT(&wildaddr, port);
		SET_SCOPE(&wildaddr, 0);

		/* check for interface/nic rules affecting the wildcard */
		action = interface_action(NULL, &wildaddr, 0);
		v6wild = (ACTION_IGNORE != action);
	}
	if (v6wild) {
		wildif = new_interface(NULL);

		strlcpy(wildif->name, "v6wildcard", sizeof(wildif->name));
		memcpy(&wildif->sin, &wildaddr, sizeof(wildif->sin));
		wildif->family = AF_INET6;
		AF(&wildif->mask) = AF_INET6;
		SET_ONESMASK(&wildif->mask);

		wildif->flags = INT_UP | INT_WILDCARD;
		wildif->ignore_packets = (ACTION_DROP == action);

		wildif->fd = open_socket(&wildif->sin, 0, 1, wildif);

		if (wildif->fd != INVALID_SOCKET) {
			wildipv6 = wildif;
			any6_interface = wildif;
			add_addr_to_list(&wildif->sin, wildif);
			add_interface(wildif);
			log_listen_address(wildif);
		} else {
			msyslog(LOG_ERR,
				"unable to bind to wildcard address %s - another process may be running - EXITING",
				stoa(&wildif->sin));
			exit(1);
		}
		DPRINT_INTERFACE(2, (wildif, "created ", "\n"));
	}
#endif

	/*
	 * create pseudo-interface with wildcard IPv4 address
	 */
	v4wild = ipv4_works;
	if (v4wild) {
		/* set wildaddr to the v4 wildcard address 0.0.0.0 */
		AF(&wildaddr) = AF_INET;
		SET_ADDR4N(&wildaddr, INADDR_ANY);
		SET_PORT(&wildaddr, port);

		/* check for interface/nic rules affecting the wildcard */
		action = interface_action(NULL, &wildaddr, 0);
		v4wild = (ACTION_IGNORE != action);
	}
	if (v4wild) {
		wildif = new_interface(NULL);

		strlcpy(wildif->name, "v4wildcard", sizeof(wildif->name));
		memcpy(&wildif->sin, &wildaddr, sizeof(wildif->sin));
		wildif->family = AF_INET;
		AF(&wildif->mask) = AF_INET;
		SET_ONESMASK(&wildif->mask);

		wildif->flags = INT_BROADCAST | INT_UP | INT_WILDCARD;
		wildif->ignore_packets = (ACTION_DROP == action);
#if defined(MCAST)
		/*
		 * enable multicast reception on the broadcast socket
		 */
		AF(&wildif->bcast) = AF_INET;
		SET_ADDR4N(&wildif->bcast, INADDR_ANY);
		SET_PORT(&wildif->bcast, port);
#endif /* MCAST */
		wildif->fd = open_socket(&wildif->sin, 0, 1, wildif);

		if (wildif->fd != INVALID_SOCKET) {
			wildipv4 = wildif;
			any_interface = wildif;

			add_addr_to_list(&wildif->sin, wildif);
			add_interface(wildif);
			log_listen_address(wildif);
		} else {
			msyslog(LOG_ERR,
				"unable to bind to wildcard address %s - another process may be running - EXITING",
				stoa(&wildif->sin));
			exit(1);
		}
		DPRINT_INTERFACE(2, (wildif, "created ", "\n"));
	}
}


/*
 * add_nic_rule() -- insert a rule entry at the head of nic_rule_list.
 */
void
add_nic_rule(
	nic_rule_match	match_type,
	const char *	if_name,	/* interface name or numeric address */
	int		prefixlen,
	nic_rule_action	action
	)
{
	nic_rule *	rule;
	isc_boolean_t	is_ip;

	rule = emalloc_zero(sizeof(*rule));
	rule->match_type = match_type;
	rule->prefixlen = prefixlen;
	rule->action = action;

	if (MATCH_IFNAME == match_type) {
		REQUIRE(NULL != if_name);
		rule->if_name = estrdup(if_name);
	} else if (MATCH_IFADDR == match_type) {
		REQUIRE(NULL != if_name);
		/* set rule->addr */
		is_ip = is_ip_address(if_name, AF_UNSPEC, &rule->addr);
		REQUIRE(is_ip);
	} else
		REQUIRE(NULL == if_name);

	LINK_SLIST(nic_rule_list, rule, next);
}


#ifdef DEBUG
static const char *
action_text(
	nic_rule_action	action
	)
{
	const char *t;

	switch (action) {

	default:
		t = "ERROR";	/* quiet uninit warning */
		DPRINTF(1, ("fatal: unknown nic_rule_action %d\n",
			    action));
		ENSURE(0);
		break;

	case ACTION_LISTEN:
		t = "listen";
		break;

	case ACTION_IGNORE:
		t = "ignore";
		break;

	case ACTION_DROP:
		t = "drop";
		break;
	}

	return t;
}
#endif	/* DEBUG */


static nic_rule_action
interface_action(
	char *		if_name,
	sockaddr_u *	if_addr,
	u_int32		if_flags
	)
{
	nic_rule *	rule;
	int		isloopback;
	int		iswildcard;

	DPRINTF(4, ("interface_action: interface %s ",
		    (if_name != NULL) ? if_name : "wildcard"));

	iswildcard = is_wildcard_addr(if_addr);
	isloopback = !!(INT_LOOPBACK & if_flags);

	/*
	 * Find any matching NIC rule from --interface / -I or ntp.conf
	 * interface/nic rules.
	 */
	for (rule = nic_rule_list; rule != NULL; rule = rule->next) {

		switch (rule->match_type) {

		case MATCH_ALL:
			/* loopback and wildcard excluded from "all" */
			if (isloopback || iswildcard)
				break;
			DPRINTF(4, ("nic all %s\n",
			    action_text(rule->action)));
			return rule->action;

		case MATCH_IPV4:
			if (IS_IPV4(if_addr)) {
				DPRINTF(4, ("nic ipv4 %s\n",
				    action_text(rule->action)));
				return rule->action;
			}
			break;

		case MATCH_IPV6:
			if (IS_IPV6(if_addr)) {
				DPRINTF(4, ("nic ipv6 %s\n",
				    action_text(rule->action)));
				return rule->action;
			}
			break;

		case MATCH_WILDCARD:
			if (iswildcard) {
				DPRINTF(4, ("nic wildcard %s\n",
				    action_text(rule->action)));
				return rule->action;
			}
			break;

		case MATCH_IFADDR:
			if (rule->prefixlen != -1) {
				if (addr_eqprefix(if_addr, &rule->addr,
						  rule->prefixlen)) {

					DPRINTF(4, ("subnet address match - %s\n",
					    action_text(rule->action)));
					return rule->action;
				}
			} else
				if (SOCK_EQ(if_addr, &rule->addr)) {

					DPRINTF(4, ("address match - %s\n",
					    action_text(rule->action)));
					return rule->action;
				}
			break;

		case MATCH_IFNAME:
			if (if_name != NULL
#if defined(HAVE_FNMATCH) && defined(FNM_CASEFOLD)
			    && !fnmatch(rule->if_name, if_name, FNM_CASEFOLD)
#else
			    && !strcasecmp(if_name, rule->if_name)
#endif
			    ) {

				DPRINTF(4, ("interface name match - %s\n",
				    action_text(rule->action)));
				return rule->action;
			}
			break;
		}
	}

	/*
	 * Unless explicitly disabled such as with "nic ignore ::1"
	 * listen on loopback addresses.  Since ntpq and ntpdc query
	 * "localhost" by default, which typically resolves to ::1 and
	 * 127.0.0.1, it's useful to default to listening on both.
	 */
	if (isloopback) {
		DPRINTF(4, ("default loopback listen\n"));
		return ACTION_LISTEN;
	}

	/*
	 * Treat wildcard addresses specially.  If there is no explicit
	 * "nic ... wildcard" or "nic ... 0.0.0.0" or "nic ... ::" rule
	 * default to drop.
	 */
	if (iswildcard) {
		DPRINTF(4, ("default wildcard drop\n"));
		return ACTION_DROP;
	}

	/*
	 * Check for "virtual IP" (colon in the interface name) after
	 * the rules so that "ntpd --interface eth0:1 -novirtualips"
	 * does indeed listen on eth0:1's addresses.
	 */
	if (!listen_to_virtual_ips && if_name != NULL
	    && (strchr(if_name, ':') != NULL)) {

		DPRINTF(4, ("virtual ip - ignore\n"));
		return ACTION_IGNORE;
	}

	/*
	 * If there are no --interface/-I command-line options and no
	 * interface/nic rules in ntp.conf, the default action is to
	 * listen.  In the presence of rules from either, the default
	 * is to ignore.  This implements ntpd's traditional listen-
	 * every default with no interface listen configuration, and
	 * ensures a single -I eth0 or "nic listen eth0" means do not
	 * listen on any other addresses.
	 */
	if (NULL == nic_rule_list) {
		DPRINTF(4, ("default listen\n"));
		return ACTION_LISTEN;
	}

	DPRINTF(4, ("implicit ignore\n"));
	return ACTION_IGNORE;
}


static void
convert_isc_if(
	isc_interface_t *isc_if,
	endpt *itf,
	u_short port
	)
{
	const u_char v6loop[16] = {0, 0, 0, 0, 0, 0, 0, 0,
				   0, 0, 0, 0, 0, 0, 0, 1};

	strlcpy(itf->name, isc_if->name, sizeof(itf->name));
	itf->ifindex = isc_if->ifindex;
	itf->family = (u_short)isc_if->af;
	AF(&itf->sin) = itf->family;
	AF(&itf->mask) = itf->family;
	AF(&itf->bcast) = itf->family;
	SET_PORT(&itf->sin, port);
	SET_PORT(&itf->mask, port);
	SET_PORT(&itf->bcast, port);

	if (IS_IPV4(&itf->sin)) {
		NSRCADR(&itf->sin) = isc_if->address.type.in.s_addr;
		NSRCADR(&itf->mask) = isc_if->netmask.type.in.s_addr;

		if (isc_if->flags & INTERFACE_F_BROADCAST) {
			itf->flags |= INT_BROADCAST;
			NSRCADR(&itf->bcast) =
			    isc_if->broadcast.type.in.s_addr;
		}
	}
#ifdef INCLUDE_IPV6_SUPPORT
	else if (IS_IPV6(&itf->sin)) {
		SET_ADDR6N(&itf->sin, isc_if->address.type.in6);
		SET_ADDR6N(&itf->mask, isc_if->netmask.type.in6);

		SET_SCOPE(&itf->sin, isc_if->address.zone);
	}
#endif /* INCLUDE_IPV6_SUPPORT */


	/* Process the rest of the flags */

	itf->flags |=
		  ((INTERFACE_F_UP & isc_if->flags)
			? INT_UP : 0)
		| ((INTERFACE_F_LOOPBACK & isc_if->flags)
			? INT_LOOPBACK : 0)
		| ((INTERFACE_F_POINTTOPOINT & isc_if->flags)
			? INT_PPP : 0)
		| ((INTERFACE_F_MULTICAST & isc_if->flags)
			? INT_MULTICAST : 0)
		| ((INTERFACE_F_PRIVACY & isc_if->flags)
			? INT_PRIVACY : 0)
		;

	/*
	 * Clear the loopback flag if the address is not localhost.
	 * http://bugs.ntp.org/1683
	 */
	if (INT_LOOPBACK & itf->flags) {
		if (AF_INET == itf->family) {
			if (127 != (SRCADR(&itf->sin) >> 24))
				itf->flags &= ~INT_LOOPBACK;
		} else {
			if (memcmp(v6loop, NSRCADR6(&itf->sin),
				   sizeof(NSRCADR6(&itf->sin))))
				itf->flags &= ~INT_LOOPBACK;
		}
	}
}


/*
 * refresh_interface
 *
 * some OSes have been observed to keep
 * cached routes even when more specific routes
 * become available.
 * this can be mitigated by re-binding
 * the socket.
 */
static int
refresh_interface(
	struct interface * interface
	)
{
#ifdef  OS_MISSES_SPECIFIC_ROUTE_UPDATES
	if (interface->fd != INVALID_SOCKET) {
		int bcast = (interface->flags & INT_BCASTXMIT) != 0;
		/* as we forcibly close() the socket remove the
		   broadcast permission indication */
		if (bcast)
			socket_broadcast_disable(interface, &interface->sin);

		close_and_delete_fd_from_list(interface->fd);

		/* create new socket picking up a new first hop binding
		   at connect() time */
		interface->fd = open_socket(&interface->sin,
					    bcast, 0, interface);
		 /*
		  * reset TTL indication so TTL is is set again
		  * next time around
		  */
		interface->last_ttl = 0;
		return (interface->fd != INVALID_SOCKET);
	} else
		return 0;	/* invalid sockets are not refreshable */
#else /* !OS_MISSES_SPECIFIC_ROUTE_UPDATES */
	return (interface->fd != INVALID_SOCKET);
#endif /* !OS_MISSES_SPECIFIC_ROUTE_UPDATES */
}

/*
 * interface_update - externally callable update function
 */
void
interface_update(
	interface_receiver_t	receiver,
	void *			data)
{
	int new_interface_found;

	if (disable_dynamic_updates)
		return;

	BLOCKIO();
	new_interface_found = update_interfaces(NTP_PORT, receiver, data);
	UNBLOCKIO();

	if (!new_interface_found)
		return;

#ifdef DEBUG
	msyslog(LOG_DEBUG, "new interface(s) found: waking up resolver");
#endif
	interrupt_worker_sleep();
}


/*
 * sau_from_netaddr() - convert network address on-wire formats.
 * Convert from libisc's isc_netaddr_t to NTP's sockaddr_u
 */
void
sau_from_netaddr(
	sockaddr_u *psau,
	const isc_netaddr_t *pna
	)
{
	ZERO_SOCK(psau);
	AF(psau) = (u_short)pna->family;
	switch (pna->family) {

	case AF_INET:
		memcpy(&psau->sa4.sin_addr, &pna->type.in,
		       sizeof(psau->sa4.sin_addr));
		break;

	case AF_INET6:
		memcpy(&psau->sa6.sin6_addr, &pna->type.in6,
		       sizeof(psau->sa6.sin6_addr));
		break;
	}
}


static int
is_wildcard_addr(
	const sockaddr_u *psau
	)
{
	if (IS_IPV4(psau) && !NSRCADR(psau))
		return 1;

#ifdef INCLUDE_IPV6_SUPPORT
	if (IS_IPV6(psau) && S_ADDR6_EQ(psau, &in6addr_any))
		return 1;
#endif

	return 0;
}


#ifdef OS_NEEDS_REUSEADDR_FOR_IFADDRBIND
/*
 * enable/disable re-use of wildcard address socket
 */
static void
set_wildcard_reuse(
	u_short	family,
	int	on
	)
{
	struct interface *any;
	SOCKET fd = INVALID_SOCKET;

	any = ANY_INTERFACE_BYFAM(family);
	if (any != NULL)
		fd = any->fd;

	if (fd != INVALID_SOCKET) {
		if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR,
			       (char *)&on, sizeof(on)))
			msyslog(LOG_ERR,
				"set_wildcard_reuse: setsockopt(SO_REUSEADDR, %s) failed: %m",
				on ? "on" : "off");

		DPRINTF(4, ("set SO_REUSEADDR to %s on %s\n",
			    on ? "on" : "off",
			    stoa(&any->sin)));
	}
}
#endif /* OS_NEEDS_REUSEADDR_FOR_IFADDRBIND */


static isc_boolean_t
check_flags6(
	sockaddr_u *psau,
	const char *name,
	u_int32 flags6
	)
{
#if defined(INCLUDE_IPV6_SUPPORT) && defined(SIOCGIFAFLAG_IN6)
	struct in6_ifreq ifr6;
	int fd;

	if (psau->sa.sa_family != AF_INET6)
		return ISC_FALSE;
	if ((fd = socket(AF_INET6, SOCK_DGRAM, 0)) < 0)
		return ISC_FALSE;
	ZERO(ifr6);
	memcpy(&ifr6.ifr_addr, &psau->sa6, sizeof(ifr6.ifr_addr));
	strlcpy(ifr6.ifr_name, name, sizeof(ifr6.ifr_name));
	if (ioctl(fd, SIOCGIFAFLAG_IN6, &ifr6) < 0) {
		close(fd);
		return ISC_FALSE;
	}
	close(fd);
	if ((ifr6.ifr_ifru.ifru_flags6 & flags6) != 0)
		return ISC_TRUE;
#endif	/* INCLUDE_IPV6_SUPPORT && SIOCGIFAFLAG_IN6 */
	return ISC_FALSE;
}

static isc_boolean_t
is_anycast(
	sockaddr_u *psau,
	const char *name
	)
{
#ifdef IN6_IFF_ANYCAST
	return check_flags6(psau, name, IN6_IFF_ANYCAST);
#else
	return ISC_FALSE;
#endif
}

static isc_boolean_t
is_valid(
	sockaddr_u *psau,
	const char *name
	)
{
	u_int32 flags6;

	flags6 = 0;
#ifdef IN6_IFF_DEPARTED
	flags6 |= IN6_IFF_DEPARTED;
#endif
#ifdef IN6_IFF_DETACHED
	flags6 |= IN6_IFF_DETACHED;
#endif
#ifdef IN6_IFF_TENTATIVE
	flags6 |= IN6_IFF_TENTATIVE;
#endif
	return check_flags6(psau, name, flags6) ? ISC_FALSE : ISC_TRUE;
}

/*
 * update_interface strategy
 *
 * toggle configuration phase
 *
 * Phase 1:
 * forall currently existing interfaces
 *   if address is known:
 *	drop socket - rebind again
 *
 *   if address is NOT known:
 *	attempt to create a new interface entry
 *
 * Phase 2:
 * forall currently known non MCAST and WILDCARD interfaces
 *   if interface does not match configuration phase (not seen in phase 1):
 *	remove interface from known interface list
 *	forall peers associated with this interface
 *         disconnect peer from this interface
 *
 * Phase 3:
 *   attempt to re-assign interfaces to peers
 *
 */

static int
update_interfaces(
	u_short			port,
	interface_receiver_t	receiver,
	void *			data
	)
{
	isc_mem_t *		mctx = (void *)-1;
	interface_info_t	ifi;
	isc_interfaceiter_t *	iter;
	isc_result_t		result;
	isc_interface_t		isc_if;
	int			new_interface_found;
	unsigned int		family;
	endpt			enumep;
	endpt *			ep;
	endpt *			next_ep;

	DPRINTF(3, ("update_interfaces(%d)\n", port));

	/*
	 * phase one - scan interfaces
	 * - create those that are not found
	 * - update those that are found
	 */

	new_interface_found = FALSE;
	iter = NULL;
	result = isc_interfaceiter_create(mctx, &iter);

	if (result != ISC_R_SUCCESS)
		return 0;

	/*
	 * Toggle system interface scan phase to find untouched
	 * interfaces to be deleted.
	 */
	sys_interphase ^= 0x1;

	for (result = isc_interfaceiter_first(iter);
	     ISC_R_SUCCESS == result;
	     result = isc_interfaceiter_next(iter)) {

		result = isc_interfaceiter_current(iter, &isc_if);

		if (result != ISC_R_SUCCESS)
			break;

		/* See if we have a valid family to use */
		family = isc_if.address.family;
		if (AF_INET != family && AF_INET6 != family)
			continue;
		if (AF_INET == family && !ipv4_works)
			continue;
		if (AF_INET6 == family && !ipv6_works)
			continue;

		/* create prototype */
		init_interface(&enumep);

		convert_isc_if(&isc_if, &enumep, port);

		DPRINT_INTERFACE(4, (&enumep, "examining ", "\n"));

		/*
		 * Check if and how we are going to use the interface.
		 */
		switch (interface_action(enumep.name, &enumep.sin,
					 enumep.flags)) {

		case ACTION_IGNORE:
			DPRINTF(4, ("ignoring interface %s (%s) - by nic rules\n",
				    enumep.name, stoa(&enumep.sin)));
			continue;

		case ACTION_LISTEN:
			DPRINTF(4, ("listen interface %s (%s) - by nic rules\n",
				    enumep.name, stoa(&enumep.sin)));
			enumep.ignore_packets = ISC_FALSE;
			break;

		case ACTION_DROP:
			DPRINTF(4, ("drop on interface %s (%s) - by nic rules\n",
				    enumep.name, stoa(&enumep.sin)));
			enumep.ignore_packets = ISC_TRUE;
			break;
		}

		 /* interfaces must be UP to be usable */
		if (!(enumep.flags & INT_UP)) {
			DPRINTF(4, ("skipping interface %s (%s) - DOWN\n",
				    enumep.name, stoa(&enumep.sin)));
			continue;
		}

		/*
		 * skip any interfaces UP and bound to a wildcard
		 * address - some dhcp clients produce that in the
		 * wild
		 */
		if (is_wildcard_addr(&enumep.sin))
			continue;

		if (is_anycast(&enumep.sin, isc_if.name))
			continue;

		/*
		 * skip any address that is an invalid state to be used
		 */
		if (!is_valid(&enumep.sin, isc_if.name))
			continue;

		/*
		 * map to local *address* in order to map all duplicate
		 * interfaces to an endpt structure with the appropriate
		 * socket.  Our name space is (ip-address), NOT
		 * (interface name, ip-address).
		 */
		ep = getinterface(&enumep.sin, INT_WILDCARD);

		if (ep != NULL && refresh_interface(ep)) {
			/*
			 * found existing and up to date interface -
			 * mark present.
			 */
			if (ep->phase != sys_interphase) {
				/*
				 * On a new round we reset the name so
				 * the interface name shows up again if
				 * this address is no longer shared.
				 * We reset ignore_packets from the
				 * new prototype to respect any runtime
				 * changes to the nic rules.
				 */
				strlcpy(ep->name, enumep.name,
					sizeof(ep->name));
				ep->ignore_packets =
					    enumep.ignore_packets;
			} else {
				/* name collision - rename interface */
				strlcpy(ep->name, "*multiple*",
					sizeof(ep->name));
			}

			DPRINT_INTERFACE(4, (ep, "updating ",
					     " present\n"));

			if (ep->ignore_packets !=
			    enumep.ignore_packets) {
				/*
				 * We have conflicting configurations
				 * for the interface address. This is
				 * caused by using -I <interfacename>
				 * for an interface that shares its
				 * address with other interfaces. We
				 * can not disambiguate incoming
				 * packets delivered to this socket
				 * without extra syscalls/features.
				 * These are not (commonly) available.
				 * Note this is a more unusual
				 * configuration where several
				 * interfaces share an address but
				 * filtering via interface name is
				 * attempted.  We resolve the
				 * configuration conflict by disabling
				 * the processing of received packets.
				 * This leads to no service on the
				 * interface address where the conflict
				 * occurs.
				 */
				msyslog(LOG_ERR,
					"WARNING: conflicting enable configuration for interfaces %s and %s for address %s - unsupported configuration - address DISABLED",
					enumep.name, ep->name,
					stoa(&enumep.sin));

				ep->ignore_packets = ISC_TRUE;
			}

			ep->phase = sys_interphase;

			ifi.action = IFS_EXISTS;
			ifi.ep = ep;
			if (receiver != NULL)
				(*receiver)(data, &ifi);
		} else {
			/*
			 * This is new or refreshing failed - add to
			 * our interface list.  If refreshing failed we
			 * will delete the interface structure in phase
			 * 2 as the interface was not marked current.
			 * We can bind to the address as the refresh
			 * code already closed the offending socket
			 */
			ep = create_interface(port, &enumep);

			if (ep != NULL) {
				ifi.action = IFS_CREATED;
				ifi.ep = ep;
				if (receiver != NULL)
					(*receiver)(data, &ifi);

				new_interface_found = TRUE;
				DPRINT_INTERFACE(3,
					(ep, "updating ",
					 " new - created\n"));
			} else {
				DPRINT_INTERFACE(3,
					(&enumep, "updating ",
					 " new - creation FAILED"));

				msyslog(LOG_INFO,
					"failed to init interface for address %s",
					stoa(&enumep.sin));
				continue;
			}
		}
	}

	isc_interfaceiter_destroy(&iter);

	/*
	 * phase 2 - delete gone interfaces - reassigning peers to
	 * other interfaces
	 */
	for (ep = ep_list; ep != NULL; ep = next_ep) {
		next_ep = ep->elink;

		/*
		 * if phase does not match sys_phase this interface was
		 * not enumerated during the last interface scan - so it
		 * is gone and will be deleted here unless it did not
		 * originate from interface enumeration (INT_WILDCARD,
		 * INT_MCASTIF).
		 */
		if (((INT_WILDCARD | INT_MCASTIF) & ep->flags) ||
		    ep->phase == sys_interphase)
			continue;

		DPRINT_INTERFACE(3, (ep, "updating ",
				     "GONE - deleting\n"));
		remove_interface(ep);

		ifi.action = IFS_DELETED;
		ifi.ep = ep;
		if (receiver != NULL)
			(*receiver)(data, &ifi);

		/* disconnect peers from deleted endpt. */
		while (ep->peers != NULL)
			set_peerdstadr(ep->peers, NULL);

		/*
		 * update globals in case we lose
		 * a loopback interface
		 */
		if (ep == loopback_interface)
			loopback_interface = NULL;

		delete_interface(ep);
	}

	/*
	 * phase 3 - re-configure as the world has possibly changed
	 *
	 * never ever make this conditional again - it is needed to track
	 * routing updates. see bug #2506
	 */
	refresh_all_peerinterfaces();

	if (broadcast_client_enabled)
		io_setbclient();

	if (sys_bclient)
		io_setbclient();

#ifdef MCAST
	/*
	 * Check multicast interfaces and try to join multicast groups if
         * not joined yet.
         */
	for (ep = ep_list; ep != NULL; ep = ep->elink) {
		remaddr_t *entry;

		if (!(INT_MCASTIF & ep->flags) || (INT_MCASTOPEN & ep->flags))
			continue;

		/* Find remote address that was linked to this interface */
		for (entry = remoteaddr_list;
		     entry != NULL;
		     entry = entry->link) {
			if (entry->ep == ep) {
				if (socket_multicast_enable(ep, &entry->addr)) {
					msyslog(LOG_INFO,
						"Joined %s socket to multicast group %s",
						stoa(&ep->sin),
						stoa(&entry->addr));
				}
				break;
			}
		}
	}
#endif /* MCAST */

	return new_interface_found;
}


/*
 * create_sockets - create a socket for each interface plus a default
 *			socket for when we don't know where to send
 */
static int
create_sockets(
	u_short port
	)
{
#ifndef HAVE_IO_COMPLETION_PORT
	/*
	 * I/O Completion Ports don't care about the select and FD_SET
	 */
	maxactivefd = 0;
	FD_ZERO(&activefds);
#endif

	DPRINTF(2, ("create_sockets(%d)\n", port));

	create_wildcards(port);

	update_interfaces(port, NULL, NULL);

	/*
	 * Now that we have opened all the sockets, turn off the reuse
	 * flag for security.
	 */
	set_reuseaddr(0);

	DPRINTF(2, ("create_sockets: Total interfaces = %d\n", ninterfaces));

	return ninterfaces;
}

/*
 * create_interface - create a new interface for a given prototype
 *		      binding the socket.
 */
static struct interface *
create_interface(
	u_short			port,
	struct interface *	protot
	)
{
	sockaddr_u	resmask;
	endpt *		iface;
#if defined(MCAST) && defined(MULTICAST_NONEWSOCKET)
	remaddr_t *	entry;
	remaddr_t *	next_entry;
#endif
	DPRINTF(2, ("create_interface(%s#%d)\n", stoa(&protot->sin),
		    port));

	/* build an interface */
	iface = new_interface(protot);

	/*
	 * create socket
	 */
	iface->fd = open_socket(&iface->sin, 0, 0, iface);

	if (iface->fd != INVALID_SOCKET)
		log_listen_address(iface);

	if ((INT_BROADCAST & iface->flags)
	    && iface->bfd != INVALID_SOCKET)
		msyslog(LOG_INFO, "Listening on broadcast address %s#%d",
			stoa((&iface->bcast)), port);

	if (INVALID_SOCKET == iface->fd
	    && INVALID_SOCKET == iface->bfd) {
		msyslog(LOG_ERR, "unable to create socket on %s (%d) for %s#%d",
			iface->name,
			iface->ifnum,
			stoa((&iface->sin)),
			port);
		delete_interface(iface);
		return NULL;
	}

	/*
	 * Blacklist our own addresses, no use talking to ourself
	 */
	SET_HOSTMASK(&resmask, AF(&iface->sin));
	hack_restrict(RESTRICT_FLAGS, &iface->sin, &resmask,
		      RESM_NTPONLY | RESM_INTERFACE, RES_IGNORE, 0);

	/*
	 * set globals with the first found
	 * loopback interface of the appropriate class
	 */
	if (NULL == loopback_interface && AF_INET == iface->family
	    && (INT_LOOPBACK & iface->flags))
		loopback_interface = iface;

	/*
	 * put into our interface list
	 */
	add_addr_to_list(&iface->sin, iface);
	add_interface(iface);

#if defined(MCAST) && defined(MULTICAST_NONEWSOCKET)
	/*
	 * Join any previously-configured compatible multicast groups.
	 */
	if (INT_MULTICAST & iface->flags &&
	    !((INT_LOOPBACK | INT_WILDCARD) & iface->flags) &&
	    !iface->ignore_packets) {
		for (entry = remoteaddr_list;
		     entry != NULL;
		     entry = next_entry) {
			next_entry = entry->link;
			if (AF(&iface->sin) != AF(&entry->addr) ||
			    !IS_MCAST(&entry->addr))
				continue;
			if (socket_multicast_enable(iface,
						    &entry->addr))
				msyslog(LOG_INFO,
					"Joined %s socket to multicast group %s",
					stoa(&iface->sin),
					stoa(&entry->addr));
			else
				msyslog(LOG_ERR,
					"Failed to join %s socket to multicast group %s",
					stoa(&iface->sin),
					stoa(&entry->addr));
		}
	}
#endif	/* MCAST && MCAST_NONEWSOCKET */

	DPRINT_INTERFACE(2, (iface, "created ", "\n"));
	return iface;
}


#ifdef SO_EXCLUSIVEADDRUSE
static void
set_excladdruse(
	SOCKET fd
	)
{
	int one = 1;
	int failed;
#ifdef SYS_WINNT
	DWORD err;
#endif

	failed = setsockopt(fd, SOL_SOCKET, SO_EXCLUSIVEADDRUSE,
			    (char *)&one, sizeof(one));

	if (!failed)
		return;

#ifdef SYS_WINNT
	/*
	 * Prior to Windows XP setting SO_EXCLUSIVEADDRUSE can fail with
	 * error WSAINVAL depending on service pack level and whether
	 * the user account is in the Administrators group.  Do not
	 * complain if it fails that way on versions prior to XP (5.1).
	 */
	err = GetLastError();

	if (isc_win32os_versioncheck(5, 1, 0, 0) < 0	/* < 5.1/XP */
	    && WSAEINVAL == err)
		return;

	SetLastError(err);
#endif
	msyslog(LOG_ERR,
		"setsockopt(%d, SO_EXCLUSIVEADDRUSE, on): %m",
		(int)fd);
}
#endif  /* SO_EXCLUSIVEADDRUSE */


/*
 * set_reuseaddr() - set/clear REUSEADDR on all sockets
 *			NB possible hole - should we be doing this on broadcast
 *			fd's also?
 */
static void
set_reuseaddr(
	int flag
	)
{
#ifndef SO_EXCLUSIVEADDRUSE
	endpt *ep;

	for (ep = ep_list; ep != NULL; ep = ep->elink) {
		if (ep->flags & INT_WILDCARD)
			continue;

		/*
		 * if ep->fd  is INVALID_SOCKET, we might have a adapter
		 * configured but not present
		 */
		DPRINTF(4, ("setting SO_REUSEADDR on %.16s@%s to %s\n",
			    ep->name, stoa(&ep->sin),
			    flag ? "on" : "off"));

		if (ep->fd != INVALID_SOCKET) {
			if (setsockopt(ep->fd, SOL_SOCKET, SO_REUSEADDR,
				       (char *)&flag, sizeof(flag))) {
				msyslog(LOG_ERR, "set_reuseaddr: setsockopt(%s, SO_REUSEADDR, %s) failed: %m",
					stoa(&ep->sin), flag ? "on" : "off");
			}
		}
	}
#endif /* ! SO_EXCLUSIVEADDRUSE */
}

/*
 * This is just a wrapper around an internal function so we can
 * make other changes as necessary later on
 */
void
enable_broadcast(
	struct interface *	iface,
	sockaddr_u *		baddr
	)
{
#ifdef OPEN_BCAST_SOCKET
	socket_broadcast_enable(iface, iface->fd, baddr);
#endif
}

#ifdef OPEN_BCAST_SOCKET
/*
 * Enable a broadcast address to a given socket
 * The socket is in the ep_list all we need to do is enable
 * broadcasting. It is not this function's job to select the socket
 */
static isc_boolean_t
socket_broadcast_enable(
	struct interface *	iface,
	SOCKET			fd,
	sockaddr_u *		baddr
	)
{
#ifdef SO_BROADCAST
	int on = 1;

	if (IS_IPV4(baddr)) {
		/* if this interface can support broadcast, set SO_BROADCAST */
		if (setsockopt(fd, SOL_SOCKET, SO_BROADCAST,
			       (char *)&on, sizeof(on)))
			msyslog(LOG_ERR,
				"setsockopt(SO_BROADCAST) enable failure on address %s: %m",
				stoa(baddr));
		else
			DPRINTF(2, ("Broadcast enabled on socket %d for address %s\n",
				    fd, stoa(baddr)));
	}
	iface->flags |= INT_BCASTXMIT;
	return ISC_TRUE;
#else
	return ISC_FALSE;
#endif /* SO_BROADCAST */
}

#ifdef  OS_MISSES_SPECIFIC_ROUTE_UPDATES
/*
 * Remove a broadcast address from a given socket
 * The socket is in the ep_list all we need to do is disable
 * broadcasting. It is not this function's job to select the socket
 */
static isc_boolean_t
socket_broadcast_disable(
	struct interface *	iface,
	sockaddr_u *		baddr
	)
{
#ifdef SO_BROADCAST
	int off = 0;	/* This seems to be OK as an int */

	if (IS_IPV4(baddr) && setsockopt(iface->fd, SOL_SOCKET,
	    SO_BROADCAST, (char *)&off, sizeof(off)))
		msyslog(LOG_ERR,
			"setsockopt(SO_BROADCAST) disable failure on address %s: %m",
			stoa(baddr));

	iface->flags &= ~INT_BCASTXMIT;
	return ISC_TRUE;
#else
	return ISC_FALSE;
#endif /* SO_BROADCAST */
}
#endif /* OS_MISSES_SPECIFIC_ROUTE_UPDATES */

#endif /* OPEN_BCAST_SOCKET */

/*
 * return the broadcast client flag value
 */
isc_boolean_t
get_broadcastclient_flag(void)
{
	return (broadcast_client_enabled);
}

/*
 * Check to see if the address is a multicast address
 */
static isc_boolean_t
addr_ismulticast(
	sockaddr_u *maddr
	)
{
	isc_boolean_t result;

#ifndef INCLUDE_IPV6_MULTICAST_SUPPORT
	/*
	 * If we don't have IPV6 support any IPV6 addr is not multicast
	 */
	if (IS_IPV6(maddr))
		result = ISC_FALSE;
	else
#endif
		result = IS_MCAST(maddr);

	if (!result)
		DPRINTF(4, ("address %s is not multicast\n",
			    stoa(maddr)));

	return result;
}

/*
 * Multicast servers need to set the appropriate Multicast interface
 * socket option in order for it to know which interface to use for
 * send the multicast packet.
 */
void
enable_multicast_if(
	struct interface *	iface,
	sockaddr_u *		maddr
	)
{
#ifdef MCAST
#ifdef IP_MULTICAST_LOOP
	TYPEOF_IP_MULTICAST_LOOP off = 0;
#endif
#if defined(INCLUDE_IPV6_MULTICAST_SUPPORT) && defined(IPV6_MULTICAST_LOOP)
	u_int off6 = 0;
#endif

	REQUIRE(AF(maddr) == AF(&iface->sin));

	switch (AF(&iface->sin)) {

	case AF_INET:
#ifdef IP_MULTICAST_LOOP
		/*
		 * Don't send back to itself, but allow failure to set
		 */
		if (setsockopt(iface->fd, IPPROTO_IP,
			       IP_MULTICAST_LOOP,
			       SETSOCKOPT_ARG_CAST &off,
			       sizeof(off))) {

			msyslog(LOG_ERR,
				"setsockopt IP_MULTICAST_LOOP failed: %m on socket %d, addr %s for multicast address %s",
				iface->fd, stoa(&iface->sin),
				stoa(maddr));
		}
#endif
		break;

	case AF_INET6:
#ifdef INCLUDE_IPV6_MULTICAST_SUPPORT
#ifdef IPV6_MULTICAST_LOOP
		/*
		 * Don't send back to itself, but allow failure to set
		 */
		if (setsockopt(iface->fd, IPPROTO_IPV6,
			       IPV6_MULTICAST_LOOP,
			       (char *) &off6, sizeof(off6))) {

			msyslog(LOG_ERR,
				"setsockopt IPV6_MULTICAST_LOOP failed: %m on socket %d, addr %s for multicast address %s",
				iface->fd, stoa(&iface->sin),
				stoa(maddr));
		}
#endif
		break;
#else
		return;
#endif	/* INCLUDE_IPV6_MULTICAST_SUPPORT */
	}
	return;
#endif
}

/*
 * Add a multicast address to a given socket
 * The socket is in the ep_list all we need to do is enable
 * multicasting. It is not this function's job to select the socket
 */
#if defined(MCAST)
static isc_boolean_t
socket_multicast_enable(
	endpt *		iface,
	sockaddr_u *	maddr
	)
{
	struct ip_mreq		mreq;
# ifdef INCLUDE_IPV6_MULTICAST_SUPPORT
	struct ipv6_mreq	mreq6;
# endif
	switch (AF(maddr)) {

	case AF_INET:
		ZERO(mreq);
		mreq.imr_multiaddr = SOCK_ADDR4(maddr);
		mreq.imr_interface.s_addr = htonl(INADDR_ANY);
		if (setsockopt(iface->fd,
			       IPPROTO_IP,
			       IP_ADD_MEMBERSHIP,
			       (char *)&mreq,
			       sizeof(mreq))) {
			DPRINTF(2, (
				"setsockopt IP_ADD_MEMBERSHIP failed: %m on socket %d, addr %s for %x / %x (%s)",
				iface->fd, stoa(&iface->sin),
				mreq.imr_multiaddr.s_addr,
				mreq.imr_interface.s_addr,
				stoa(maddr)));
			return ISC_FALSE;
		}
		DPRINTF(4, ("Added IPv4 multicast membership on socket %d, addr %s for %x / %x (%s)\n",
			    iface->fd, stoa(&iface->sin),
			    mreq.imr_multiaddr.s_addr,
			    mreq.imr_interface.s_addr, stoa(maddr)));
		break;

	case AF_INET6:
# ifdef INCLUDE_IPV6_MULTICAST_SUPPORT
		/*
		 * Enable reception of multicast packets.
		 * If the address is link-local we can get the
		 * interface index from the scope id. Don't do this
		 * for other types of multicast addresses. For now let
		 * the kernel figure it out.
		 */
		ZERO(mreq6);
		mreq6.ipv6mr_multiaddr = SOCK_ADDR6(maddr);
		mreq6.ipv6mr_interface = iface->ifindex;

		if (setsockopt(iface->fd, IPPROTO_IPV6,
			       IPV6_JOIN_GROUP, (char *)&mreq6,
			       sizeof(mreq6))) {
			DPRINTF(2, (
				"setsockopt IPV6_JOIN_GROUP failed: %m on socket %d, addr %s for interface %u (%s)",
				iface->fd, stoa(&iface->sin),
				mreq6.ipv6mr_interface, stoa(maddr)));
			return ISC_FALSE;
		}
		DPRINTF(4, ("Added IPv6 multicast group on socket %d, addr %s for interface %u (%s)\n",
			    iface->fd, stoa(&iface->sin),
			    mreq6.ipv6mr_interface, stoa(maddr)));
# else
		return ISC_FALSE;
# endif	/* INCLUDE_IPV6_MULTICAST_SUPPORT */
	}
	iface->flags |= INT_MCASTOPEN;
	iface->num_mcast++;

	return ISC_TRUE;
}
#endif	/* MCAST */


/*
 * Remove a multicast address from a given socket
 * The socket is in the ep_list all we need to do is disable
 * multicasting. It is not this function's job to select the socket
 */
#ifdef MCAST
static isc_boolean_t
socket_multicast_disable(
	struct interface *	iface,
	sockaddr_u *		maddr
	)
{
# ifdef INCLUDE_IPV6_MULTICAST_SUPPORT
	struct ipv6_mreq mreq6;
# endif
	struct ip_mreq mreq;

	ZERO(mreq);

	if (find_addr_in_list(maddr) == NULL) {
		DPRINTF(4, ("socket_multicast_disable(%s): not found\n",
			    stoa(maddr)));
		return ISC_TRUE;
	}

	switch (AF(maddr)) {

	case AF_INET:
		mreq.imr_multiaddr = SOCK_ADDR4(maddr);
		mreq.imr_interface = SOCK_ADDR4(&iface->sin);
		if (setsockopt(iface->fd, IPPROTO_IP,
			       IP_DROP_MEMBERSHIP, (char *)&mreq,
			       sizeof(mreq))) {

			msyslog(LOG_ERR,
				"setsockopt IP_DROP_MEMBERSHIP failed: %m on socket %d, addr %s for %x / %x (%s)",
				iface->fd, stoa(&iface->sin),
				SRCADR(maddr), SRCADR(&iface->sin),
				stoa(maddr));
			return ISC_FALSE;
		}
		break;
	case AF_INET6:
# ifdef INCLUDE_IPV6_MULTICAST_SUPPORT
		/*
		 * Disable reception of multicast packets
		 * If the address is link-local we can get the
		 * interface index from the scope id.  Don't do this
		 * for other types of multicast addresses. For now let
		 * the kernel figure it out.
		 */
		mreq6.ipv6mr_multiaddr = SOCK_ADDR6(maddr);
		mreq6.ipv6mr_interface = iface->ifindex;

		if (setsockopt(iface->fd, IPPROTO_IPV6,
			       IPV6_LEAVE_GROUP, (char *)&mreq6,
			       sizeof(mreq6))) {

			msyslog(LOG_ERR,
				"setsockopt IPV6_LEAVE_GROUP failure: %m on socket %d, addr %s for %d (%s)",
				iface->fd, stoa(&iface->sin),
				iface->ifindex, stoa(maddr));
			return ISC_FALSE;
		}
		break;
# else
		return ISC_FALSE;
# endif	/* INCLUDE_IPV6_MULTICAST_SUPPORT */
	}

	iface->num_mcast--;
	if (!iface->num_mcast)
		iface->flags &= ~INT_MCASTOPEN;

	return ISC_TRUE;
}
#endif	/* MCAST */

/*
 * io_setbclient - open the broadcast client sockets
 */
void
io_setbclient(void)
{
#ifdef OPEN_BCAST_SOCKET
	struct interface *	interf;
	unsigned int		nif;

	nif = 0;
	set_reuseaddr(1);

	for (interf = ep_list;
	     interf != NULL;
	     interf = interf->elink) {

		if (interf->flags & (INT_WILDCARD | INT_LOOPBACK))
			continue;

		/* use only allowed addresses */
		if (interf->ignore_packets)
			continue;

		/* Need a broadcast-capable interface */
		if (!(interf->flags & INT_BROADCAST))
			continue;

		/* Only IPv4 addresses are valid for broadcast */
		REQUIRE(IS_IPV4(&interf->bcast));

		/* Do we already have the broadcast address open? */
		if (interf->flags & INT_BCASTOPEN) {
			/*
			 * account for already open interfaces to avoid
			 * misleading warning below
			 */
			nif++;
			continue;
		}

		/*
		 * Try to open the broadcast address
		 */
		interf->family = AF_INET;
		interf->bfd = open_socket(&interf->bcast, 1, 0, interf);

		/*
		 * If we succeeded then we use it otherwise enable
		 * broadcast on the interface address
		 */
		if (interf->bfd != INVALID_SOCKET) {
			nif++;
			interf->flags |= INT_BCASTOPEN;
			msyslog(LOG_INFO,
				"Listen for broadcasts to %s on interface #%d %s",
				stoa(&interf->bcast), interf->ifnum, interf->name);
		} else switch (errno) {
			/* Silently ignore EADDRINUSE as we probably
			 * opened the socket already for an address in
			 * the same network */
		case EADDRINUSE:
			/* Some systems cannot bind a socket to a broadcast
			 * address, as that is not a valid host address. */
		case EADDRNOTAVAIL:
#		    ifdef SYS_WINNT	/*TODO: use for other systems, too? */
			/* avoid recurrence here -- if we already have a
			 * regular socket, it's quite useless to try this
			 * again.
			 */
			if (interf->fd != INVALID_SOCKET) {
				interf->flags |= INT_BCASTOPEN;
				nif++;
			}
#		    endif
			break;

		default:
			msyslog(LOG_INFO,
				"failed to listen for broadcasts to %s on interface #%d %s",
				stoa(&interf->bcast), interf->ifnum, interf->name);
			break;
		}
	}
	set_reuseaddr(0);
	if (nif != 0) {
		broadcast_client_enabled = ISC_TRUE;
		DPRINTF(1, ("io_setbclient: listening to %d broadcast addresses\n", nif));
	} else {
		broadcast_client_enabled = ISC_FALSE;
		msyslog(LOG_ERR,
			"Unable to listen for broadcasts, no broadcast interfaces available");
	}
#else
	msyslog(LOG_ERR,
		"io_setbclient: Broadcast Client disabled by build");
#endif	/* OPEN_BCAST_SOCKET */
}

/*
 * io_unsetbclient - close the broadcast client sockets
 */
void
io_unsetbclient(void)
{
	endpt *ep;

	for (ep = ep_list; ep != NULL; ep = ep->elink) {
		if (INT_WILDCARD & ep->flags)
			continue;
		if (!(INT_BCASTOPEN & ep->flags))
			continue;

		if (ep->bfd != INVALID_SOCKET) {
			/* destroy broadcast listening socket */
			msyslog(LOG_INFO,
				"stop listening for broadcasts to %s on interface #%d %s",
				stoa(&ep->bcast), ep->ifnum, ep->name);
#		    ifdef HAVE_IO_COMPLETION_PORT
			io_completion_port_remove_socket(ep->bfd, ep);
#		    endif
			close_and_delete_fd_from_list(ep->bfd);
			ep->bfd = INVALID_SOCKET;
		}
		ep->flags &= ~INT_BCASTOPEN;
	}
	broadcast_client_enabled = ISC_FALSE;
}

/*
 * io_multicast_add() - add multicast group address
 */
void
io_multicast_add(
	sockaddr_u *addr
	)
{
#ifdef MCAST
	endpt *	ep;
	endpt *	one_ep;

	/*
	 * Check to see if this is a multicast address
	 */
	if (!addr_ismulticast(addr))
		return;

	/* If we already have it we can just return */
	if (NULL != find_flagged_addr_in_list(addr, INT_MCASTOPEN)) {
		msyslog(LOG_INFO,
			"Duplicate request found for multicast address %s",
			stoa(addr));
		return;
	}

# ifndef MULTICAST_NONEWSOCKET
	ep = new_interface(NULL);

	/*
	 * Open a new socket for the multicast address
	 */
	ep->sin = *addr;
	SET_PORT(&ep->sin, NTP_PORT);
	ep->family = AF(&ep->sin);
	AF(&ep->mask) = ep->family;
	SET_ONESMASK(&ep->mask);

	set_reuseaddr(1);
	ep->bfd = INVALID_SOCKET;
	ep->fd = open_socket(&ep->sin, 0, 0, ep);
	if (ep->fd != INVALID_SOCKET) {
		ep->ignore_packets = ISC_FALSE;
		ep->flags |= INT_MCASTIF;

		strlcpy(ep->name, "multicast", sizeof(ep->name));
		DPRINT_INTERFACE(2, (ep, "multicast add ", "\n"));
		add_interface(ep);
		log_listen_address(ep);
	} else {
		/* bind failed, re-use wildcard interface */
		delete_interface(ep);

		if (IS_IPV4(addr))
			ep = wildipv4;
		else if (IS_IPV6(addr))
			ep = wildipv6;
		else
			ep = NULL;

		if (ep != NULL) {
			/* HACK ! -- stuff in an address */
			/* because we don't bind addr? DH */
			ep->bcast = *addr;
			msyslog(LOG_ERR,
				"multicast address %s using wildcard interface #%d %s",
				stoa(addr), ep->ifnum, ep->name);
		} else {
			msyslog(LOG_ERR,
				"No multicast socket available to use for address %s",
				stoa(addr));
			return;
		}
	}
	{	/* in place of the { following for in #else clause */
		one_ep = ep;
# else	/* MULTICAST_NONEWSOCKET follows */
	/*
	 * For the case where we can't use a separate socket (Windows)
	 * join each applicable endpoint socket to the group address.
	 */
	if (IS_IPV4(addr))
		one_ep = wildipv4;
	else
		one_ep = wildipv6;
	for (ep = ep_list; ep != NULL; ep = ep->elink) {
		if (ep->ignore_packets || AF(&ep->sin) != AF(addr) ||
		    !(INT_MULTICAST & ep->flags) ||
		    (INT_LOOPBACK | INT_WILDCARD) & ep->flags)
			continue;
		one_ep = ep;
# endif	/* MULTICAST_NONEWSOCKET */
		if (socket_multicast_enable(ep, addr))
			msyslog(LOG_INFO,
				"Joined %s socket to multicast group %s",
				stoa(&ep->sin),
				stoa(addr));
	}

	add_addr_to_list(addr, one_ep);
#else	/* !MCAST  follows*/
	msyslog(LOG_ERR,
		"Can not add multicast address %s: no multicast support",
		stoa(addr));
#endif
	return;
}


/*
 * io_multicast_del() - delete multicast group address
 */
void
io_multicast_del(
	sockaddr_u *	addr
	)
{
#ifdef MCAST
	endpt *iface;

	/*
	 * Check to see if this is a multicast address
	 */
	if (!addr_ismulticast(addr)) {
		msyslog(LOG_ERR, "invalid multicast address %s",
			stoa(addr));
		return;
	}

	/*
	 * Disable reception of multicast packets
	 */
	while ((iface = find_flagged_addr_in_list(addr, INT_MCASTOPEN))
	       != NULL)
		socket_multicast_disable(iface, addr);

	delete_addr_from_list(addr);

#else /* not MCAST */
	msyslog(LOG_ERR,
		"Can not delete multicast address %s: no multicast support",
		stoa(addr));
#endif /* not MCAST */
}


/*
 * open_socket - open a socket, returning the file descriptor
 */

static SOCKET
open_socket(
	sockaddr_u *	addr,
	int		bcast,
	int		turn_off_reuse,
	endpt *		interf
	)
{
	SOCKET	fd;
	int	errval;
	/*
	 * int is OK for REUSEADR per
	 * http://www.kohala.com/start/mcast.api.txt
	 */
	int	on = 1;
	int	off = 0;

	if (IS_IPV6(addr) && !ipv6_works)
		return INVALID_SOCKET;

	/* create a datagram (UDP) socket */
	fd = socket(AF(addr), SOCK_DGRAM, 0);
	if (INVALID_SOCKET == fd) {
		errval = socket_errno();
		msyslog(LOG_ERR,
			"socket(AF_INET%s, SOCK_DGRAM, 0) failed on address %s: %m",
			IS_IPV6(addr) ? "6" : "", stoa(addr));

		if (errval == EPROTONOSUPPORT ||
		    errval == EAFNOSUPPORT ||
		    errval == EPFNOSUPPORT)
			return (INVALID_SOCKET);

		errno = errval;
		msyslog(LOG_ERR,
			"unexpected socket() error %m code %d (not EPROTONOSUPPORT nor EAFNOSUPPORT nor EPFNOSUPPORT) - exiting",
			errno);
		exit(1);
	}

#ifdef SYS_WINNT
	connection_reset_fix(fd, addr);
#endif
	/*
	 * Fixup the file descriptor for some systems
	 * See bug #530 for details of the issue.
	 */
	fd = move_fd(fd);

	/*
	 * set SO_REUSEADDR since we will be binding the same port
	 * number on each interface according to turn_off_reuse.
	 * This is undesirable on Windows versions starting with
	 * Windows XP (numeric version 5.1).
	 */
#ifdef SYS_WINNT
	if (isc_win32os_versioncheck(5, 1, 0, 0) < 0)  /* before 5.1 */
#endif
		if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR,
			       (char *)((turn_off_reuse)
					    ? &off
					    : &on),
			       sizeof(on))) {

			msyslog(LOG_ERR,
				"setsockopt SO_REUSEADDR %s fails for address %s: %m",
				(turn_off_reuse)
				    ? "off"
				    : "on",
				stoa(addr));
			closesocket(fd);
			return INVALID_SOCKET;
		}
#ifdef SO_EXCLUSIVEADDRUSE
	/*
	 * setting SO_EXCLUSIVEADDRUSE on the wildcard we open
	 * first will cause more specific binds to fail.
	 */
	if (!(interf->flags & INT_WILDCARD))
		set_excladdruse(fd);
#endif

	/*
	 * IPv4 specific options go here
	 */
	if (IS_IPV4(addr)) {
#if defined(IPPROTO_IP) && defined(IP_TOS)
		if (setsockopt(fd, IPPROTO_IP, IP_TOS, (char*)&qos,
			       sizeof(qos)))
			msyslog(LOG_ERR,
				"setsockopt IP_TOS (%02x) fails on address %s: %m",
				qos, stoa(addr));
#endif /* IPPROTO_IP && IP_TOS */
		if (bcast)
			socket_broadcast_enable(interf, fd, addr);
	}

	/*
	 * IPv6 specific options go here
	 */
	if (IS_IPV6(addr)) {
#if defined(IPPROTO_IPV6) && defined(IPV6_TCLASS)
		if (setsockopt(fd, IPPROTO_IPV6, IPV6_TCLASS, (char*)&qos,
			       sizeof(qos)))
			msyslog(LOG_ERR,
				"setsockopt IPV6_TCLASS (%02x) fails on address %s: %m",
				qos, stoa(addr));
#endif /* IPPROTO_IPV6 && IPV6_TCLASS */
#ifdef IPV6_V6ONLY
		if (isc_net_probe_ipv6only() == ISC_R_SUCCESS
		    && setsockopt(fd, IPPROTO_IPV6, IPV6_V6ONLY,
		    (char*)&on, sizeof(on)))
			msyslog(LOG_ERR,
				"setsockopt IPV6_V6ONLY on fails on address %s: %m",
				stoa(addr));
#endif
#ifdef IPV6_BINDV6ONLY
		if (setsockopt(fd, IPPROTO_IPV6, IPV6_BINDV6ONLY,
		    (char*)&on, sizeof(on)))
			msyslog(LOG_ERR,
				"setsockopt IPV6_BINDV6ONLY on fails on address %s: %m",
				stoa(addr));
#endif
	}

#ifdef OS_NEEDS_REUSEADDR_FOR_IFADDRBIND
	/*
	 * some OSes don't allow binding to more specific
	 * addresses if a wildcard address already bound
	 * to the port and SO_REUSEADDR is not set
	 */
	if (!is_wildcard_addr(addr))
		set_wildcard_reuse(AF(addr), 1);
#endif

	/*
	 * bind the local address.
	 */
	errval = bind(fd, &addr->sa, SOCKLEN(addr));

#ifdef OS_NEEDS_REUSEADDR_FOR_IFADDRBIND
	if (!is_wildcard_addr(addr))
		set_wildcard_reuse(AF(addr), 0);
#endif

	if (errval < 0) {
		/*
		 * Don't log this under all conditions
		 */
		if (turn_off_reuse == 0
#ifdef DEBUG
		    || debug > 1
#endif
		    ) {
			msyslog(LOG_ERR,
				"bind(%d) AF_INET%s %s#%d%s flags 0x%x failed: %m",
				fd, IS_IPV6(addr) ? "6" : "",
				stoa(addr), SRCPORT(addr),
				IS_MCAST(addr) ? " (multicast)" : "",
				interf->flags);
		}

		closesocket(fd);

		return INVALID_SOCKET;
	}

#ifdef HAVE_TIMESTAMP
	{
		if (setsockopt(fd, SOL_SOCKET, SO_TIMESTAMP,
			       (char*)&on, sizeof(on)))
			msyslog(LOG_DEBUG,
				"setsockopt SO_TIMESTAMP on fails on address %s: %m",
				stoa(addr));
		else
			DPRINTF(4, ("setsockopt SO_TIMESTAMP enabled on fd %d address %s\n",
				    fd, stoa(addr)));
	}
#endif
#ifdef HAVE_TIMESTAMPNS
	{
		if (setsockopt(fd, SOL_SOCKET, SO_TIMESTAMPNS,
			       (char*)&on, sizeof(on)))
			msyslog(LOG_DEBUG,
				"setsockopt SO_TIMESTAMPNS on fails on address %s: %m",
				stoa(addr));
		else
			DPRINTF(4, ("setsockopt SO_TIMESTAMPNS enabled on fd %d address %s\n",
				    fd, stoa(addr)));
	}
#endif
#ifdef HAVE_BINTIME
	{
		if (setsockopt(fd, SOL_SOCKET, SO_BINTIME,
			       (char*)&on, sizeof(on)))
			msyslog(LOG_DEBUG,
				"setsockopt SO_BINTIME on fails on address %s: %m",
				stoa(addr));
		else
			DPRINTF(4, ("setsockopt SO_BINTIME enabled on fd %d address %s\n",
				    fd, stoa(addr)));
	}
#endif

	DPRINTF(4, ("bind(%d) AF_INET%s, addr %s%%%d#%d, flags 0x%x\n",
		   fd, IS_IPV6(addr) ? "6" : "", stoa(addr),
		   SCOPE(addr), SRCPORT(addr), interf->flags));

	make_socket_nonblocking(fd);

#ifdef HAVE_SIGNALED_IO
	init_socket_sig(fd);
#endif /* not HAVE_SIGNALED_IO */

	add_fd_to_list(fd, FD_TYPE_SOCKET);

#if !defined(SYS_WINNT) && !defined(VMS)
	DPRINTF(4, ("flags for fd %d: 0x%x\n", fd,
		    fcntl(fd, F_GETFL, 0)));
#endif /* SYS_WINNT || VMS */

#if defined(HAVE_IO_COMPLETION_PORT)
/*
 * Add the socket to the completion port
 */
	if (!io_completion_port_add_socket(fd, interf, bcast)) {
		msyslog(LOG_ERR, "unable to set up io completion port - EXITING");
		exit(1);
	}
#endif
	return fd;
}



/* XXX ELIMINATE sendpkt similar in ntpq.c, ntpdc.c, ntp_io.c, ntptrace.c */
/*
 * sendpkt - send a packet to the specified destination. Maintain a
 * send error cache so that only the first consecutive error for a
 * destination is logged.
 */
void
sendpkt(
	sockaddr_u *		dest,
	struct interface *	ep,
	int			ttl,
	struct pkt *		pkt,
	int			len
	)
{
	endpt *	src;
	int	ismcast;
	int	cc;
	int	rc;
	u_char	cttl;

	ismcast = IS_MCAST(dest);
	if (!ismcast)
		src = ep;
	else
		src = (IS_IPV4(dest))
			  ? mc4_list
			  : mc6_list;

	if (NULL == src) {
		/*
		 * unbound peer - drop request and wait for better
		 * network conditions
		 */
		DPRINTF(2, ("%ssendpkt(dst=%s, ttl=%d, len=%d): no interface - IGNORED\n",
			    ismcast ? "\tMCAST\t***** " : "",
			    stoa(dest), ttl, len));
		return;
	}

	do {
		DPRINTF(2, ("%ssendpkt(%d, dst=%s, src=%s, ttl=%d, len=%d)\n",
			    ismcast ? "\tMCAST\t***** " : "", src->fd,
			    stoa(dest), stoa(&src->sin), ttl, len));
#ifdef MCAST
		/*
		 * for the moment we use the bcast option to set multicast ttl
		 */
		if (ismcast && ttl > 0 && ttl != src->last_ttl) {
			/*
			 * set the multicast ttl for outgoing packets
			 */
			switch (AF(&src->sin)) {

			case AF_INET :
				cttl = (u_char)ttl;
				rc = setsockopt(src->fd, IPPROTO_IP,
						IP_MULTICAST_TTL,
						(void *)&cttl,
						sizeof(cttl));
				break;

# ifdef INCLUDE_IPV6_SUPPORT
			case AF_INET6 :
				rc = setsockopt(src->fd, IPPROTO_IPV6,
						 IPV6_MULTICAST_HOPS,
						 (void *)&ttl,
						 sizeof(ttl));
				break;
# endif	/* INCLUDE_IPV6_SUPPORT */

			default:
				rc = 0;
			}

			if (!rc)
				src->last_ttl = ttl;
			else
				msyslog(LOG_ERR,
					"setsockopt IP_MULTICAST_TTL/IPV6_MULTICAST_HOPS fails on address %s: %m",
					stoa(&src->sin));
		}
#endif	/* MCAST */

#ifdef SIM
		cc = simulate_server(dest, src, pkt);
#elif defined(HAVE_IO_COMPLETION_PORT)
		cc = io_completion_port_sendto(src, src->fd, pkt,
			(size_t)len, (sockaddr_u *)&dest->sa);
#else
		cc = sendto(src->fd, (char *)pkt, (u_int)len, 0,
			    &dest->sa, SOCKLEN(dest));
#endif
		if (cc == -1) {
			src->notsent++;
			packets_notsent++;
		} else	{
			src->sent++;
			packets_sent++;
		}
		if (ismcast)
			src = src->mclink;
	} while (ismcast && src != NULL);
}


#if !defined(HAVE_IO_COMPLETION_PORT)
#if !defined(HAVE_SIGNALED_IO)
/*
 * fdbits - generate ascii representation of fd_set (FAU debug support)
 * HFDF format - highest fd first.
 */
static char *
fdbits(
	int		count,
	const fd_set*	set
	)
{
	static char buffer[256];
	char * buf = buffer;

	count = min(count,  255);

	while (count >= 0) {
		*buf++ = FD_ISSET(count, set) ? '#' : '-';
		count--;
	}
	*buf = '\0';

	return buffer;
}
#endif

#ifdef REFCLOCK
/*
 * Routine to read the refclock packets for a specific interface
 * Return the number of bytes read. That way we know if we should
 * read it again or go on to the next one if no bytes returned
 */
static inline int
read_refclock_packet(
	SOCKET			fd,
	struct refclockio *	rp,
	l_fp			ts
	)
{
	u_int			read_count;
	int			buflen;
	int			saved_errno;
	int			consumed;
	struct recvbuf *	rb;

	rb = get_free_recv_buffer();

	if (NULL == rb) {
		/*
		 * No buffer space available - just drop the packet
		 */
		char buf[RX_BUFF_SIZE];

		buflen = read(fd, buf, sizeof buf);
		packets_dropped++;
		return (buflen);
	}

	/* TALOS-CAN-0064: avoid signed/unsigned clashes that can lead
	 * to buffer overrun and memory corruption
	 */
	if (rp->datalen <= 0 || (size_t)rp->datalen > sizeof(rb->recv_space))
		read_count = sizeof(rb->recv_space);
	else
		read_count = (u_int)rp->datalen;
	do {
		buflen = read(fd, (char *)&rb->recv_space, read_count);
	} while (buflen < 0 && EINTR == errno);

	if (buflen <= 0) {
		saved_errno = errno;
		freerecvbuf(rb);
		errno = saved_errno;
		return buflen;
	}

	/*
	 * Got one. Mark how and when it got here,
	 * put it on the full list and do bookkeeping.
	 */
	rb->recv_length = buflen;
	rb->recv_peer = rp->srcclock;
	rb->dstadr = 0;
	rb->fd = fd;
	rb->recv_time = ts;
	rb->receiver = rp->clock_recv;

	consumed = indicate_refclock_packet(rp, rb);
	if (!consumed) {
		rp->recvcount++;
		packets_received++;
	}

	return buflen;
}
#endif	/* REFCLOCK */


#ifdef HAVE_PACKET_TIMESTAMP
/*
 * extract timestamps from control message buffer
 */
static l_fp
fetch_timestamp(
	struct recvbuf *	rb,
	struct msghdr *		msghdr,
	l_fp			ts
	)
{
	struct cmsghdr *	cmsghdr;
	unsigned long		ticks;
	double			fuzz;
	l_fp			lfpfuzz;
	l_fp			nts;
#ifdef DEBUG_TIMING
	l_fp			dts;
#endif

	cmsghdr = CMSG_FIRSTHDR(msghdr);
	while (cmsghdr != NULL) {
		switch (cmsghdr->cmsg_type)
		{
#ifdef HAVE_BINTIME
		case SCM_BINTIME:
#endif  /* HAVE_BINTIME */
#ifdef HAVE_TIMESTAMPNS
		case SCM_TIMESTAMPNS:
#endif	/* HAVE_TIMESTAMPNS */
#ifdef HAVE_TIMESTAMP
		case SCM_TIMESTAMP:
#endif	/* HAVE_TIMESTAMP */
#if defined(HAVE_BINTIME) || defined (HAVE_TIMESTAMPNS) || defined(HAVE_TIMESTAMP)
			switch (cmsghdr->cmsg_type)
			{
#ifdef HAVE_BINTIME
			case SCM_BINTIME:
				{
					struct bintime	pbt;
					memcpy(&pbt, CMSG_DATA(cmsghdr), sizeof(pbt));
					/*
					 * bintime documentation is at http://phk.freebsd.dk/pubs/timecounter.pdf
					 */
					nts.l_i = pbt.sec + JAN_1970;
					nts.l_uf = (u_int32)(pbt.frac >> 32);
					if (sys_tick > measured_tick &&
					    sys_tick > 1e-9) {
						ticks = (unsigned long)(nts.l_uf / (unsigned long)(sys_tick * FRAC));
						nts.l_uf = (unsigned long)(ticks * (unsigned long)(sys_tick * FRAC));
					}
					DPRINTF(4, ("fetch_timestamp: system bintime network time stamp: %ld.%09lu\n",
						    pbt.sec, (unsigned long)((nts.l_uf / FRAC) * 1e9)));
				}
				break;
#endif  /* HAVE_BINTIME */
#ifdef HAVE_TIMESTAMPNS
			case SCM_TIMESTAMPNS:
				{
					struct timespec	pts;
					memcpy(&pts, CMSG_DATA(cmsghdr), sizeof(pts));
					if (sys_tick > measured_tick &&
					    sys_tick > 1e-9) {
						ticks = (unsigned long)((pts.tv_nsec * 1e-9) /
									sys_tick);
						pts.tv_nsec = (long)(ticks * 1e9 *
								     sys_tick);
					}
					DPRINTF(4, ("fetch_timestamp: system nsec network time stamp: %ld.%09ld\n",
						    pts.tv_sec, pts.tv_nsec));
					nts = tspec_stamp_to_lfp(pts);
				}
				break;
#endif	/* HAVE_TIMESTAMPNS */
#ifdef HAVE_TIMESTAMP
			case SCM_TIMESTAMP:
				{
					struct timeval	ptv;
					memcpy(&ptv, CMSG_DATA(cmsghdr), sizeof(ptv));
					if (sys_tick > measured_tick &&
					    sys_tick > 1e-6) {
						ticks = (unsigned long)((ptv.tv_usec * 1e-6) /
									sys_tick);
						ptv.tv_usec = (long)(ticks * 1e6 *
								    sys_tick);
					}
					DPRINTF(4, ("fetch_timestamp: system usec network time stamp: %jd.%06ld\n",
						    (intmax_t)ptv.tv_sec, (long)ptv.tv_usec));
					nts = tval_stamp_to_lfp(ptv);
				}
				break;
#endif  /* HAVE_TIMESTAMP */
			}
			fuzz = ntp_random() * 2. / FRAC * sys_fuzz;
			DTOLFP(fuzz, &lfpfuzz);
			L_ADD(&nts, &lfpfuzz);
#ifdef DEBUG_TIMING
			dts = ts;
			L_SUB(&dts, &nts);
			collect_timing(rb, "input processing delay", 1,
				       &dts);
			DPRINTF(4, ("fetch_timestamp: timestamp delta: %s (incl. fuzz)\n",
				    lfptoa(&dts, 9)));
#endif	/* DEBUG_TIMING */
			ts = nts;  /* network time stamp */
			break;
#endif	/* HAVE_BINTIME || HAVE_TIMESTAMPNS || HAVE_TIMESTAMP */

		default:
			DPRINTF(4, ("fetch_timestamp: skipping control message 0x%x\n",
				    cmsghdr->cmsg_type));
		}
		cmsghdr = CMSG_NXTHDR(msghdr, cmsghdr);
	}
	return ts;
}
#endif	/* HAVE_PACKET_TIMESTAMP */


/*
 * Routine to read the network NTP packets for a specific interface
 * Return the number of bytes read. That way we know if we should
 * read it again or go on to the next one if no bytes returned
 */
static inline int
read_network_packet(
	SOCKET			fd,
	struct interface *	itf,
	l_fp			ts
	)
{
	GETSOCKNAME_SOCKLEN_TYPE fromlen;
	int buflen;
	register struct recvbuf *rb;
#ifdef HAVE_PACKET_TIMESTAMP
	struct msghdr msghdr;
	struct iovec iovec;
	char control[CMSG_BUFSIZE];
#endif

	/*
	 * Get a buffer and read the frame.  If we
	 * haven't got a buffer, or this is received
	 * on a disallowed socket, just dump the
	 * packet.
	 */

	rb = get_free_recv_buffer();
	if (NULL == rb || itf->ignore_packets) {
		char buf[RX_BUFF_SIZE];
		sockaddr_u from;

		if (rb != NULL)
			freerecvbuf(rb);

		fromlen = sizeof(from);
		buflen = recvfrom(fd, buf, sizeof(buf), 0,
				  &from.sa, &fromlen);
		DPRINTF(4, ("%s on (%lu) fd=%d from %s\n",
			(itf->ignore_packets)
			    ? "ignore"
			    : "drop",
			free_recvbuffs(), fd, stoa(&from)));
		if (itf->ignore_packets)
			packets_ignored++;
		else
			packets_dropped++;
		return (buflen);
	}

	fromlen = sizeof(rb->recv_srcadr);

#ifndef HAVE_PACKET_TIMESTAMP
	rb->recv_length = recvfrom(fd, (char *)&rb->recv_space,
				   sizeof(rb->recv_space), 0,
				   &rb->recv_srcadr.sa, &fromlen);
#else
	iovec.iov_base        = &rb->recv_space;
	iovec.iov_len         = sizeof(rb->recv_space);
	msghdr.msg_name       = &rb->recv_srcadr;
	msghdr.msg_namelen    = fromlen;
	msghdr.msg_iov        = &iovec;
	msghdr.msg_iovlen     = 1;
	msghdr.msg_control    = (void *)&control;
	msghdr.msg_controllen = sizeof(control);
	msghdr.msg_flags      = 0;
	rb->recv_length       = recvmsg(fd, &msghdr, 0);
#endif

	buflen = rb->recv_length;

	if (buflen == 0 || (buflen == -1 &&
	    (EWOULDBLOCK == errno
#ifdef EAGAIN
	     || EAGAIN == errno
#endif
	     ))) {
		freerecvbuf(rb);
		return (buflen);
	} else if (buflen < 0) {
		msyslog(LOG_ERR, "recvfrom(%s) fd=%d: %m",
			stoa(&rb->recv_srcadr), fd);
		DPRINTF(5, ("read_network_packet: fd=%d dropped (bad recvfrom)\n",
			    fd));
		freerecvbuf(rb);
		return (buflen);
	}

	DPRINTF(3, ("read_network_packet: fd=%d length %d from %s\n",
		    fd, buflen, stoa(&rb->recv_srcadr)));

#ifdef ENABLE_BUG3020_FIX
	if (ISREFCLOCKADR(&rb->recv_srcadr)) {
		msyslog(LOG_ERR, "recvfrom(%s) fd=%d: refclock srcadr on a network interface!",
			stoa(&rb->recv_srcadr), fd);
		DPRINTF(1, ("read_network_packet: fd=%d dropped (refclock srcadr))\n",
			    fd));
		packets_dropped++;
		freerecvbuf(rb);
		return (buflen);
	}
#endif

	/*
	** Bug 2672: Some OSes (MacOSX and Linux) don't block spoofed ::1
	*/

	if (AF_INET6 == itf->family) {
		DPRINTF(2, ("Got an IPv6 packet, from <%s> (%d) to <%s> (%d)\n",
			stoa(&rb->recv_srcadr),
			IN6_IS_ADDR_LOOPBACK(PSOCK_ADDR6(&rb->recv_srcadr)),
			stoa(&itf->sin),
			!IN6_IS_ADDR_LOOPBACK(PSOCK_ADDR6(&itf->sin))
			));

		if (   IN6_IS_ADDR_LOOPBACK(PSOCK_ADDR6(&rb->recv_srcadr))
		    && !IN6_IS_ADDR_LOOPBACK(PSOCK_ADDR6(&itf->sin))
		   ) {
			packets_dropped++;
			DPRINTF(2, ("DROPPING that packet\n"));
			freerecvbuf(rb);
			return buflen;
		}
		DPRINTF(2, ("processing that packet\n"));
	}

	/*
	 * Got one.  Mark how and when it got here,
	 * put it on the full list and do bookkeeping.
	 */
	rb->dstadr = itf;
	rb->fd = fd;
#ifdef HAVE_PACKET_TIMESTAMP
	/* pick up a network time stamp if possible */
	ts = fetch_timestamp(rb, &msghdr, ts);
#endif
	rb->recv_time = ts;
	rb->receiver = receive;

	add_full_recv_buffer(rb);

	itf->received++;
	packets_received++;
	return (buflen);
}

/*
 * attempt to handle io (select()/signaled IO)
 */
void
io_handler(void)
{
#  ifndef HAVE_SIGNALED_IO
	fd_set rdfdes;
	int nfound;

	/*
	 * Use select() on all on all input fd's for unlimited
	 * time.  select() will terminate on SIGALARM or on the
	 * reception of input.	Using select() means we can't do
	 * robust signal handling and we get a potential race
	 * between checking for alarms and doing the select().
	 * Mostly harmless, I think.
	 */
	/*
	 * On VMS, I suspect that select() can't be interrupted
	 * by a "signal" either, so I take the easy way out and
	 * have select() time out after one second.
	 * System clock updates really aren't time-critical,
	 * and - lacking a hardware reference clock - I have
	 * yet to learn about anything else that is.
	 */
	++handler_calls;
	rdfdes = activefds;
#   if !defined(VMS) && !defined(SYS_VXWORKS)
	nfound = select(maxactivefd + 1, &rdfdes, NULL,
			NULL, NULL);
#   else	/* VMS, VxWorks */
	/* make select() wake up after one second */
	{
		struct timeval t1;
		t1.tv_sec  = 1;
		t1.tv_usec = 0;
		nfound = select(maxactivefd + 1,
				&rdfdes, NULL, NULL,
				&t1);
	}
#   endif	/* VMS, VxWorks */
	if (nfound < 0 && sanitize_fdset(errno)) {
		struct timeval t1;
		t1.tv_sec  = 0;
		t1.tv_usec = 0;
		rdfdes = activefds;
		nfound = select(maxactivefd + 1,
				&rdfdes, NULL, NULL,
				&t1);
	}

	if (nfound > 0) {
		l_fp ts;

		get_systime(&ts);

		input_handler_scan(&ts, &rdfdes);
	} else if (nfound == -1 && errno != EINTR) {
		msyslog(LOG_ERR, "select() error: %m");
	}
#   ifdef DEBUG
	else if (debug > 4) {
		msyslog(LOG_DEBUG, "select(): nfound=%d, error: %m", nfound);
	} else {
		DPRINTF(3, ("select() returned %d: %m\n", nfound));
	}
#   endif /* DEBUG */
#  else /* HAVE_SIGNALED_IO */
	wait_for_signal();
#  endif /* HAVE_SIGNALED_IO */
}

#ifdef HAVE_SIGNALED_IO
/*
 * input_handler - receive packets asynchronously
 *
 * ALWAYS IN SIGNAL HANDLER CONTEXT -- only async-safe functions allowed!
 */
static RETSIGTYPE
input_handler(
	l_fp *	cts
	)
{
	int		n;
	struct timeval	tvzero;
	fd_set		fds;
	
	++handler_calls;

	/*
	 * Do a poll to see who has data
	 */

	fds = activefds;
	tvzero.tv_sec = tvzero.tv_usec = 0;

	n = select(maxactivefd + 1, &fds, NULL, NULL, &tvzero);
	if (n < 0 && sanitize_fdset(errno)) {
		fds = activefds;
		tvzero.tv_sec = tvzero.tv_usec = 0;
		n = select(maxactivefd + 1, &fds, NULL, NULL, &tvzero);
	}
	if (n > 0)
		input_handler_scan(cts, &fds);
}
#endif /* HAVE_SIGNALED_IO */


/*
 * Try to sanitize the global FD set
 *
 * SIGNAL HANDLER CONTEXT if HAVE_SIGNALED_IO, ordinary userspace otherwise
 */
static int/*BOOL*/
sanitize_fdset(
	int	errc
	)
{
	int j, b, maxscan;

#  ifndef HAVE_SIGNALED_IO
	/*
	 * extended FAU debugging output
	 */
	if (errc != EINTR) {
		msyslog(LOG_ERR,
			"select(%d, %s, 0L, 0L, &0.0) error: %m",
			maxactivefd + 1,
			fdbits(maxactivefd, &activefds));
	}
#   endif
	
	if (errc != EBADF)
		return FALSE;

	/* if we have oviously bad FDs, try to sanitize the FD set. */
	for (j = 0, maxscan = 0; j <= maxactivefd; j++) {
		if (FD_ISSET(j, &activefds)) {
			if (-1 != read(j, &b, 0)) {
				maxscan = j;
				continue;
			}
#		    ifndef HAVE_SIGNALED_IO
			msyslog(LOG_ERR,
				"Removing bad file descriptor %d from select set",
				j);
#		    endif
			FD_CLR(j, &activefds);
		}
	}
	if (maxactivefd != maxscan)
		maxactivefd = maxscan;
	return TRUE;
}

/*
 * scan the known FDs (clocks, servers, ...) for presence in a 'fd_set'. 
 *
 * SIGNAL HANDLER CONTEXT if HAVE_SIGNALED_IO, ordinary userspace otherwise
 */
static void
input_handler_scan(
	const l_fp *	cts,
	const fd_set *	pfds
	)
{
	int		buflen;
	u_int		idx;
	int		doing;
	SOCKET		fd;
	blocking_child *c;
	l_fp		ts;	/* Timestamp at BOselect() gob */

#if defined(DEBUG_TIMING)
	l_fp		ts_e;	/* Timestamp at EOselect() gob */
#endif
	endpt *		ep;
#ifdef REFCLOCK
	struct refclockio *rp;
	int		saved_errno;
	const char *	clk;
#endif
#ifdef HAS_ROUTING_SOCKET
	struct asyncio_reader *	asyncio_reader;
	struct asyncio_reader *	next_asyncio_reader;
#endif

	++handler_pkts;
	ts = *cts;

#ifdef REFCLOCK
	/*
	 * Check out the reference clocks first, if any
	 */
	
	for (rp = refio; rp != NULL; rp = rp->next) {
		fd = rp->fd;
		
		if (!FD_ISSET(fd, pfds))
			continue;
		buflen = read_refclock_packet(fd, rp, ts);
		/*
		 * The first read must succeed after select() indicates
		 * readability, or we've reached a permanent EOF.
		 * http://bugs.ntp.org/1732 reported ntpd munching CPU
		 * after a USB GPS was unplugged because select was
		 * indicating EOF but ntpd didn't remove the descriptor
		 * from the activefds set.
		 */
		if (buflen < 0 && EAGAIN != errno) {
			saved_errno = errno;
			clk = refnumtoa(&rp->srcclock->srcadr);
			errno = saved_errno;
			msyslog(LOG_ERR, "%s read: %m", clk);
			maintain_activefds(fd, TRUE);
		} else if (0 == buflen) {
			clk = refnumtoa(&rp->srcclock->srcadr);
			msyslog(LOG_ERR, "%s read EOF", clk);
			maintain_activefds(fd, TRUE);
		} else {
			/* drain any remaining refclock input */
			do {
				buflen = read_refclock_packet(fd, rp, ts);
			} while (buflen > 0);
		}
	}
#endif /* REFCLOCK */

	/*
	 * Loop through the interfaces looking for data to read.
	 */
	for (ep = ep_list; ep != NULL; ep = ep->elink) {
		for (doing = 0; doing < 2; doing++) {
			if (!doing) {
				fd = ep->fd;
			} else {
				if (!(ep->flags & INT_BCASTOPEN))
					break;
				fd = ep->bfd;
			}
			if (fd < 0)
				continue;
			if (FD_ISSET(fd, pfds))
				do {
					buflen = read_network_packet(
							fd, ep, ts);
				} while (buflen > 0);
			/* Check more interfaces */
		}
	}

#ifdef HAS_ROUTING_SOCKET
	/*
	 * scan list of asyncio readers - currently only used for routing sockets
	 */
	asyncio_reader = asyncio_reader_list;

	while (asyncio_reader != NULL) {
		/* callback may unlink and free asyncio_reader */
		next_asyncio_reader = asyncio_reader->link;
		if (FD_ISSET(asyncio_reader->fd, pfds))
			(*asyncio_reader->receiver)(asyncio_reader);
		asyncio_reader = next_asyncio_reader;
	}
#endif /* HAS_ROUTING_SOCKET */

	/*
	 * Check for a response from a blocking child
	 */
	for (idx = 0; idx < blocking_children_alloc; idx++) {
		c = blocking_children[idx];
		if (NULL == c || -1 == c->resp_read_pipe)
			continue;
		if (FD_ISSET(c->resp_read_pipe, pfds)) {
			++c->resp_ready_seen;
			++blocking_child_ready_seen;
		}
	}

	/* We've done our work */
#if defined(DEBUG_TIMING)
	get_systime(&ts_e);
	/*
	 * (ts_e - ts) is the amount of time we spent
	 * processing this gob of file descriptors.  Log
	 * it.
	 */
	L_SUB(&ts_e, &ts);
	collect_timing(NULL, "input handler", 1, &ts_e);
	if (debug > 3)
		msyslog(LOG_DEBUG,
			"input_handler: Processed a gob of fd's in %s msec",
			lfptoms(&ts_e, 6));
#endif /* DEBUG_TIMING */
}
#endif /* !HAVE_IO_COMPLETION_PORT */

/*
 * find an interface suitable for the src address
 */
endpt *
select_peerinterface(
	struct peer *	peer,
	sockaddr_u *	srcadr,
	endpt *		dstadr
	)
{
	endpt *ep;
#ifndef SIM
	endpt *wild;

	wild = ANY_INTERFACE_CHOOSE(srcadr);

	/*
	 * Initialize the peer structure and dance the interface jig.
	 * Reference clocks step the loopback waltz, the others
	 * squaredance around the interface list looking for a buddy. If
	 * the dance peters out, there is always the wildcard interface.
	 * This might happen in some systems and would preclude proper
	 * operation with public key cryptography.
	 */
	if (ISREFCLOCKADR(srcadr)) {
		ep = loopback_interface;
	} else if (peer->cast_flags &
		   (MDF_BCLNT | MDF_ACAST | MDF_MCAST | MDF_BCAST)) {
		ep = findbcastinter(srcadr);
		if (ep != NULL)
			DPRINTF(4, ("Found *-cast interface %s for address %s\n",
				stoa(&ep->sin), stoa(srcadr)));
		else
			DPRINTF(4, ("No *-cast local address found for address %s\n",
				stoa(srcadr)));
	} else {
		ep = dstadr;
		if (NULL == ep)
			ep = wild;
	}
	/*
	 * If it is a multicast address, findbcastinter() may not find
	 * it.  For unicast, we get to find the interface when dstadr is
	 * given to us as the wildcard (ANY_INTERFACE_CHOOSE).  Either
	 * way, try a little harder.
	 */
	if (wild == ep)
		ep = findinterface(srcadr);
	/*
	 * we do not bind to the wildcard interfaces for output
	 * as our (network) source address would be undefined and
	 * crypto will not work without knowing the own transmit address
	 */
	if (ep != NULL && INT_WILDCARD & ep->flags)
		if (!accept_wildcard_if_for_winnt)
			ep = NULL;
#else	/* SIM follows */
	ep = loopback_interface;
#endif

	return ep;
}


/*
 * findinterface - find local interface corresponding to address
 */
endpt *
findinterface(
	sockaddr_u *addr
	)
{
	endpt *iface;

	iface = findlocalinterface(addr, INT_WILDCARD, 0);

	if (NULL == iface) {
		DPRINTF(4, ("Found no interface for address %s - returning wildcard\n",
			    stoa(addr)));

		iface = ANY_INTERFACE_CHOOSE(addr);
	} else
		DPRINTF(4, ("Found interface #%d %s for address %s\n",
			    iface->ifnum, iface->name, stoa(addr)));

	return iface;
}

/*
 * findlocalinterface - find local interface corresponding to addr,
 * which does not have any of flags set.  If bast is nonzero, addr is
 * a broadcast address.
 *
 * This code attempts to find the local sending address for an outgoing
 * address by connecting a new socket to destinationaddress:NTP_PORT
 * and reading the sockname of the resulting connect.
 * the complicated sequence simulates the routing table lookup
 * for to first hop without duplicating any of the routing logic into
 * ntpd. preferably we would have used an API call - but its not there -
 * so this is the best we can do here short of duplicating to entire routing
 * logic in ntpd which would be a silly and really unportable thing to do.
 *
 */
static endpt *
findlocalinterface(
	sockaddr_u *	addr,
	int		flags,
	int		bcast
	)
{
	GETSOCKNAME_SOCKLEN_TYPE	sockaddrlen;
	endpt *				iface;
	sockaddr_u			saddr;
	SOCKET				s;
	int				rtn;
	int				on;

	DPRINTF(4, ("Finding interface for addr %s in list of addresses\n",
		    stoa(addr)));

	s = socket(AF(addr), SOCK_DGRAM, 0);
	if (INVALID_SOCKET == s)
		return NULL;

	/*
	 * If we are looking for broadcast interface we need to set this
	 * socket to allow broadcast
	 */
	if (bcast) {
		on = 1;
		if (SOCKET_ERROR == setsockopt(s, SOL_SOCKET,
						SO_BROADCAST,
						(char *)&on,
						sizeof(on))) {
			closesocket(s);
			return NULL;
		}
	}

	rtn = connect(s, &addr->sa, SOCKLEN(addr));
	if (SOCKET_ERROR == rtn) {
		closesocket(s);
		return NULL;
	}

	sockaddrlen = sizeof(saddr);
	rtn = getsockname(s, &saddr.sa, &sockaddrlen);
	closesocket(s);
	if (SOCKET_ERROR == rtn)
		return NULL;

	DPRINTF(4, ("findlocalinterface: kernel maps %s to %s\n",
		    stoa(addr), stoa(&saddr)));

	iface = getinterface(&saddr, flags);

	/*
	 * if we didn't find an exact match on saddr, find the closest
	 * available local address.  This handles the case of the
	 * address suggested by the kernel being excluded by nic rules
	 * or the user's -I and -L options to ntpd.
	 * See http://bugs.ntp.org/1184 and http://bugs.ntp.org/1683
	 * for more background.
	 */
	if (NULL == iface || iface->ignore_packets)
		iface = findclosestinterface(&saddr,
					     flags | INT_LOOPBACK);

	/* Don't use an interface which will ignore replies */
	if (iface != NULL && iface->ignore_packets)
		iface = NULL;

	return iface;
}


/*
 * findclosestinterface
 *
 * If there are -I/--interface or -L/novirtualips command-line options,
 * or "nic" or "interface" rules in ntp.conf, findlocalinterface() may
 * find the kernel's preferred local address for a given peer address is
 * administratively unavailable to ntpd, and punt to this routine's more
 * expensive search.
 *
 * Find the numerically closest local address to the one connect()
 * suggested.  This matches an address on the same subnet first, as
 * needed by Bug 1184, and provides a consistent choice if there are
 * multiple feasible local addresses, regardless of the order ntpd
 * enumerated them.
 */
endpt *
findclosestinterface(
	sockaddr_u *	addr,
	int		flags
	)
{
	endpt *		ep;
	endpt *		winner;
	sockaddr_u	addr_dist;
	sockaddr_u	min_dist;

	ZERO_SOCK(&min_dist);
	winner = NULL;

	for (ep = ep_list; ep != NULL; ep = ep->elink) {
		if (ep->ignore_packets ||
		    AF(addr) != ep->family ||
		    flags & ep->flags)
			continue;

		calc_addr_distance(&addr_dist, addr, &ep->sin);
		if (NULL == winner ||
		    -1 == cmp_addr_distance(&addr_dist, &min_dist)) {
			min_dist = addr_dist;
			winner = ep;
		}
	}
	if (NULL == winner)
		DPRINTF(4, ("findclosestinterface(%s) failed\n",
			    stoa(addr)));
	else
		DPRINTF(4, ("findclosestinterface(%s) -> %s\n",
			    stoa(addr), stoa(&winner->sin)));

	return winner;
}


/*
 * calc_addr_distance - calculate the distance between two addresses,
 *			the absolute value of the difference between
 *			the addresses numerically, stored as an address.
 */
static void
calc_addr_distance(
	sockaddr_u *		dist,
	const sockaddr_u *	a1,
	const sockaddr_u *	a2
	)
{
	u_int32	a1val;
	u_int32	a2val;
	u_int32	v4dist;
	int	found_greater;
	int	a1_greater;
	int	i;

	REQUIRE(AF(a1) == AF(a2));

	ZERO_SOCK(dist);
	AF(dist) = AF(a1);

	/* v4 can be done a bit simpler */
	if (IS_IPV4(a1)) {
		a1val = SRCADR(a1);
		a2val = SRCADR(a2);
		v4dist = (a1val > a2val)
			     ? a1val - a2val
			     : a2val - a1val;
		SET_ADDR4(dist, v4dist);

		return;
	}

	found_greater = FALSE;
	a1_greater = FALSE;	/* suppress pot. uninit. warning */
	for (i = 0; i < (int)sizeof(NSRCADR6(a1)); i++) {
		if (!found_greater &&
		    NSRCADR6(a1)[i] != NSRCADR6(a2)[i]) {
			found_greater = TRUE;
			a1_greater = (NSRCADR6(a1)[i] > NSRCADR6(a2)[i]);
		}
		if (!found_greater) {
			NSRCADR6(dist)[i] = 0;
		} else {
			if (a1_greater)
				NSRCADR6(dist)[i] = NSRCADR6(a1)[i] -
						    NSRCADR6(a2)[i];
			else
				NSRCADR6(dist)[i] = NSRCADR6(a2)[i] -
						    NSRCADR6(a1)[i];
		}
	}
}


/*
 * cmp_addr_distance - compare two address distances, returning -1, 0,
 *		       1 to indicate their relationship.
 */
static int
cmp_addr_distance(
	const sockaddr_u *	d1,
	const sockaddr_u *	d2
	)
{
	int	i;

	REQUIRE(AF(d1) == AF(d2));

	if (IS_IPV4(d1)) {
		if (SRCADR(d1) < SRCADR(d2))
			return -1;
		else if (SRCADR(d1) == SRCADR(d2))
			return 0;
		else
			return 1;
	}

	for (i = 0; i < (int)sizeof(NSRCADR6(d1)); i++) {
		if (NSRCADR6(d1)[i] < NSRCADR6(d2)[i])
			return -1;
		else if (NSRCADR6(d1)[i] > NSRCADR6(d2)[i])
			return 1;
	}

	return 0;
}



/*
 * fetch an interface structure the matches the
 * address and has the given flags NOT set
 */
endpt *
getinterface(
	sockaddr_u *	addr,
	u_int32		flags
	)
{
	endpt *iface;

	iface = find_addr_in_list(addr);

	if (iface != NULL && (iface->flags & flags))
		iface = NULL;

	return iface;
}


/*
 * findbcastinter - find broadcast interface corresponding to address
 */
endpt *
findbcastinter(
	sockaddr_u *addr
	)
{
	endpt *	iface;

	iface = NULL;
#if !defined(MPE) && (defined(SIOCGIFCONF) || defined(SYS_WINNT))
	DPRINTF(4, ("Finding broadcast/multicast interface for addr %s in list of addresses\n",
		    stoa(addr)));

	iface = findlocalinterface(addr, INT_LOOPBACK | INT_WILDCARD,
				   1);
	if (iface != NULL) {
		DPRINTF(4, ("Easily found bcast-/mcast- interface index #%d %s\n",
			    iface->ifnum, iface->name));
		return iface;
	}

	/*
	 * plan B - try to find something reasonable in our lists in
	 * case kernel lookup doesn't help
	 */
	for (iface = ep_list; iface != NULL; iface = iface->elink) {
		if (iface->flags & INT_WILDCARD)
			continue;

		/* Don't bother with ignored interfaces */
		if (iface->ignore_packets)
			continue;

		/*
		 * First look if this is the correct family
		 */
		if(AF(&iface->sin) != AF(addr))
			continue;

		/* Skip the loopback addresses */
		if (iface->flags & INT_LOOPBACK)
			continue;

		/*
		 * If we are looking to match a multicast address and
		 * this interface is one...
		 */
		if (addr_ismulticast(addr)
		    && (iface->flags & INT_MULTICAST)) {
#ifdef INCLUDE_IPV6_SUPPORT
			/*
			 * ...it is the winner unless we're looking for
			 * an interface to use for link-local multicast
			 * and its address is not link-local.
			 */
			if (IS_IPV6(addr)
			    && IN6_IS_ADDR_MC_LINKLOCAL(PSOCK_ADDR6(addr))
			    && !IN6_IS_ADDR_LINKLOCAL(PSOCK_ADDR6(&iface->sin)))
				continue;
#endif
			break;
		}

		/*
		 * We match only those interfaces marked as
		 * broadcastable and either the explicit broadcast
		 * address or the network portion of the IP address.
		 * Sloppy.
		 */
		if (IS_IPV4(addr)) {
			if (SOCK_EQ(&iface->bcast, addr))
				break;

			if ((NSRCADR(&iface->sin) & NSRCADR(&iface->mask))
			    == (NSRCADR(addr)	  & NSRCADR(&iface->mask)))
				break;
		}
#ifdef INCLUDE_IPV6_SUPPORT
		else if (IS_IPV6(addr)) {
			if (SOCK_EQ(&iface->bcast, addr))
				break;

			if (SOCK_EQ(netof(&iface->sin), netof(addr)))
				break;
		}
#endif
	}
#endif /* SIOCGIFCONF */
	if (NULL == iface) {
		DPRINTF(4, ("No bcast interface found for %s\n",
			    stoa(addr)));
		iface = ANY_INTERFACE_CHOOSE(addr);
	} else {
		DPRINTF(4, ("Found bcast-/mcast- interface index #%d %s\n",
			    iface->ifnum, iface->name));
	}

	return iface;
}


/*
 * io_clr_stats - clear I/O module statistics
 */
void
io_clr_stats(void)
{
	packets_dropped = 0;
	packets_ignored = 0;
	packets_received = 0;
	packets_sent = 0;
	packets_notsent = 0;

	handler_calls = 0;
	handler_pkts = 0;
	io_timereset = current_time;
}


#ifdef REFCLOCK
/*
 * io_addclock - add a reference clock to the list and arrange that we
 *				 get SIGIO interrupts from it.
 */
int
io_addclock(
	struct refclockio *rio
	)
{
	BLOCKIO();

	/*
	 * Stuff the I/O structure in the list and mark the descriptor
	 * in use.  There is a harmless (I hope) race condition here.
	 */
	rio->active = TRUE;

# ifdef HAVE_SIGNALED_IO
	if (init_clock_sig(rio)) {
		UNBLOCKIO();
		return 0;
	}
# elif defined(HAVE_IO_COMPLETION_PORT)
	if (!io_completion_port_add_clock_io(rio)) {
		UNBLOCKIO();
		return 0;
	}
# endif

	/*
	 * enqueue
	 */
	LINK_SLIST(refio, rio, next);

	/*
	 * register fd
	 */
	add_fd_to_list(rio->fd, FD_TYPE_FILE);

	UNBLOCKIO();
	return 1;
}


/*
 * io_closeclock - close the clock in the I/O structure given
 */
void
io_closeclock(
	struct refclockio *rio
	)
{
	struct refclockio *unlinked;

	BLOCKIO();

	/*
	 * Remove structure from the list
	 */
	rio->active = FALSE;
	UNLINK_SLIST(unlinked, refio, rio, next, struct refclockio);
	if (NULL != unlinked) {
		/* Close the descriptor. The order of operations is
		 * important here in case of async / overlapped IO:
		 * only after we have removed the clock from the
		 * IO completion port we can be sure no further
		 * input is queued. So...
		 *  - we first disable feeding to the queu by removing
		 *    the clock from the IO engine
		 *  - close the file (which brings down any IO on it)
		 *  - clear the buffer from results for this fd
		 */
#	    ifdef HAVE_IO_COMPLETION_PORT
		io_completion_port_remove_clock_io(rio);
#	    endif
		close_and_delete_fd_from_list(rio->fd);
		purge_recv_buffers_for_fd(rio->fd);
		rio->fd = -1;
	}

	UNBLOCKIO();
}
#endif	/* REFCLOCK */


/*
 * On NT a SOCKET is an unsigned int so we cannot possibly keep it in
 * an array. So we use one of the ISC_LIST functions to hold the
 * socket value and use that when we want to enumerate it.
 *
 * This routine is called by the forked intres child process to close
 * all open sockets.  On Windows there's no need as intres runs in
 * the same process as a thread.
 */
#ifndef SYS_WINNT
void
kill_asyncio(
	int	startfd
	)
{
	BLOCKIO();

	/*
	 * In the child process we do not maintain activefds and
	 * maxactivefd.  Zeroing maxactivefd disables code which
	 * maintains it in close_and_delete_fd_from_list().
	 */
	maxactivefd = 0;

	while (fd_list != NULL)
		close_and_delete_fd_from_list(fd_list->fd);

	UNBLOCKIO();
}
#endif	/* !SYS_WINNT */


/*
 * Add and delete functions for the list of open sockets
 */
static void
add_fd_to_list(
	SOCKET fd,
	enum desc_type type
	)
{
	vsock_t *lsock = emalloc(sizeof(*lsock));

	lsock->fd = fd;
	lsock->type = type;

	LINK_SLIST(fd_list, lsock, link);
	maintain_activefds(fd, 0);
}


static void
close_and_delete_fd_from_list(
	SOCKET fd
	)
{
	vsock_t *lsock;

	UNLINK_EXPR_SLIST(lsock, fd_list, fd ==
	    UNLINK_EXPR_SLIST_CURRENT()->fd, link, vsock_t);

	if (NULL == lsock)
		return;

	switch (lsock->type) {

	case FD_TYPE_SOCKET:
		closesocket(lsock->fd);
		break;

	case FD_TYPE_FILE:
		closeserial((int)lsock->fd);
		break;

	default:
		msyslog(LOG_ERR,
			"internal error - illegal descriptor type %d - EXITING",
			(int)lsock->type);
		exit(1);
	}

	free(lsock);
	/*
	 * remove from activefds
	 */
	maintain_activefds(fd, 1);
}


static void
add_addr_to_list(
	sockaddr_u *	addr,
	endpt *		ep
	)
{
	remaddr_t *laddr;

#ifdef DEBUG
	if (find_addr_in_list(addr) == NULL) {
#endif
		/* not there yet - add to list */
		laddr = emalloc(sizeof(*laddr));
		laddr->addr = *addr;
		laddr->ep = ep;

		LINK_SLIST(remoteaddr_list, laddr, link);

		DPRINTF(4, ("Added addr %s to list of addresses\n",
			    stoa(addr)));
#ifdef DEBUG
	} else
		DPRINTF(4, ("WARNING: Attempt to add duplicate addr %s to address list\n",
			    stoa(addr)));
#endif
}


static void
delete_addr_from_list(
	sockaddr_u *addr
	)
{
	remaddr_t *unlinked;

	UNLINK_EXPR_SLIST(unlinked, remoteaddr_list, SOCK_EQ(addr,
		&(UNLINK_EXPR_SLIST_CURRENT()->addr)), link, remaddr_t);

	if (unlinked != NULL) {
		DPRINTF(4, ("Deleted addr %s from list of addresses\n",
			stoa(addr)));
		free(unlinked);
	}
}


static void
delete_interface_from_list(
	endpt *iface
	)
{
	remaddr_t *unlinked;

	for (;;) {
		UNLINK_EXPR_SLIST(unlinked, remoteaddr_list, iface ==
		    UNLINK_EXPR_SLIST_CURRENT()->ep, link,
		    remaddr_t);

		if (unlinked == NULL)
			break;
		DPRINTF(4, ("Deleted addr %s for interface #%d %s from list of addresses\n",
			    stoa(&unlinked->addr), iface->ifnum,
			    iface->name));
		free(unlinked);
	}
}


static struct interface *
find_addr_in_list(
	sockaddr_u *addr
	)
{
	remaddr_t *entry;

	DPRINTF(4, ("Searching for addr %s in list of addresses - ",
		    stoa(addr)));

	for (entry = remoteaddr_list;
	     entry != NULL;
	     entry = entry->link)
		if (SOCK_EQ(&entry->addr, addr)) {
			DPRINTF(4, ("FOUND\n"));
			return entry->ep;
		}

	DPRINTF(4, ("NOT FOUND\n"));
	return NULL;
}


/*
 * Find the given address with the all given flags set in the list
 */
static endpt *
find_flagged_addr_in_list(
	sockaddr_u *	addr,
	u_int32		flags
	)
{
	remaddr_t *entry;

	DPRINTF(4, ("Finding addr %s with flags %d in list: ",
		    stoa(addr), flags));

	for (entry = remoteaddr_list;
	     entry != NULL;
	     entry = entry->link)

		if (SOCK_EQ(&entry->addr, addr)
		    && (entry->ep->flags & flags) == flags) {

			DPRINTF(4, ("FOUND\n"));
			return entry->ep;
		}

	DPRINTF(4, ("NOT FOUND\n"));
	return NULL;
}


const char *
localaddrtoa(
	endpt *la
	)
{
	return (NULL == la)
		   ? "<null>"
		   : stoa(&la->sin);
}


#ifdef HAS_ROUTING_SOCKET
# ifndef UPDATE_GRACE
#  define UPDATE_GRACE	2	/* wait UPDATE_GRACE seconds before scanning */
# endif

static void
process_routing_msgs(struct asyncio_reader *reader)
{
	char buffer[5120];
	int cnt, msg_type;
#ifdef HAVE_RTNETLINK
	struct nlmsghdr *nh;
#else
	struct rt_msghdr rtm;
	char *p;
#endif

	if (disable_dynamic_updates) {
		/*
		 * discard ourselves if we are not needed any more
		 * usually happens when running unprivileged
		 */
		remove_asyncio_reader(reader);
		delete_asyncio_reader(reader);
		return;
	}

	cnt = read(reader->fd, buffer, sizeof(buffer));

	if (cnt < 0) {
		if (errno == ENOBUFS) {
			msyslog(LOG_ERR,
				"routing socket reports: %m");
		} else {
			msyslog(LOG_ERR,
				"routing socket reports: %m - disabling");
			remove_asyncio_reader(reader);
			delete_asyncio_reader(reader);
		}
		return;
	}

	/*
	 * process routing message
	 */
#ifdef HAVE_RTNETLINK
	for (nh = UA_PTR(struct nlmsghdr, buffer);
	     NLMSG_OK(nh, cnt);
	     nh = NLMSG_NEXT(nh, cnt)) {
		msg_type = nh->nlmsg_type;
#else
	for (p = buffer;
	     (p + sizeof(struct rt_msghdr)) <= (buffer + cnt);
	     p += rtm.rtm_msglen) {
		memcpy(&rtm, p, sizeof(rtm));
		if (rtm.rtm_version != RTM_VERSION) {
			msyslog(LOG_ERR,
				"version mismatch (got %d - expected %d) on routing socket - disabling",
				rtm.rtm_version, RTM_VERSION);

			remove_asyncio_reader(reader);
			delete_asyncio_reader(reader);
			return;
		}
		msg_type = rtm.rtm_type;
#endif
		switch (msg_type) {
#ifdef RTM_NEWADDR
		case RTM_NEWADDR:
#endif
#ifdef RTM_DELADDR
		case RTM_DELADDR:
#endif
#ifdef RTM_ADD
		case RTM_ADD:
#endif
#ifdef RTM_DELETE
		case RTM_DELETE:
#endif
#ifdef RTM_REDIRECT
		case RTM_REDIRECT:
#endif
#ifdef RTM_CHANGE
		case RTM_CHANGE:
#endif
#ifdef RTM_LOSING
		case RTM_LOSING:
#endif
#ifdef RTM_IFINFO
		case RTM_IFINFO:
#endif
#ifdef RTM_IFANNOUNCE
		case RTM_IFANNOUNCE:
#endif
#ifdef RTM_NEWLINK
		case RTM_NEWLINK:
#endif
#ifdef RTM_DELLINK
		case RTM_DELLINK:
#endif
#ifdef RTM_NEWROUTE
		case RTM_NEWROUTE:
#endif
#ifdef RTM_DELROUTE
		case RTM_DELROUTE:
#endif
			/*
			 * we are keen on new and deleted addresses and
			 * if an interface goes up and down or routing
			 * changes
			 */
			DPRINTF(3, ("routing message op = %d: scheduling interface update\n",
				    msg_type));
			timer_interfacetimeout(current_time + UPDATE_GRACE);
			break;
#ifdef HAVE_RTNETLINK
		case NLMSG_DONE:
			/* end of multipart message */
			return;
#endif
		default:
			/*
			 * the rest doesn't bother us.
			 */
			DPRINTF(4, ("routing message op = %d: ignored\n",
				    msg_type));
			break;
		}
	}
}

/*
 * set up routing notifications
 */
static void
init_async_notifications()
{
	struct asyncio_reader *reader;
#ifdef HAVE_RTNETLINK
	int fd = socket(PF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
	struct sockaddr_nl sa;
#else
	int fd = socket(PF_ROUTE, SOCK_RAW, 0);
#endif
	if (fd < 0) {
		msyslog(LOG_ERR,
			"unable to open routing socket (%m) - using polled interface update");
		return;
	}

	fd = move_fd(fd);
#ifdef HAVE_RTNETLINK
	ZERO(sa);
	sa.nl_family = PF_NETLINK;
	sa.nl_groups = RTMGRP_LINK | RTMGRP_IPV4_IFADDR
		       | RTMGRP_IPV6_IFADDR | RTMGRP_IPV4_ROUTE
		       | RTMGRP_IPV4_MROUTE | RTMGRP_IPV6_ROUTE
		       | RTMGRP_IPV6_MROUTE;
	if (bind(fd, (struct sockaddr *)&sa, sizeof(sa)) < 0) {
		msyslog(LOG_ERR,
			"bind failed on routing socket (%m) - using polled interface update");
		return;
	}
#endif
	make_socket_nonblocking(fd);
#if defined(HAVE_SIGNALED_IO)
	init_socket_sig(fd);
#endif /* HAVE_SIGNALED_IO */

	reader = new_asyncio_reader();

	reader->fd = fd;
	reader->receiver = process_routing_msgs;

	add_asyncio_reader(reader, FD_TYPE_SOCKET);
	msyslog(LOG_INFO,
		"Listening on routing socket on fd #%d for interface updates",
		fd);
}
#else
/* HAS_ROUTING_SOCKET not defined */
static void
init_async_notifications(void)
{
}
#endif