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-rw-r--r--usr.sbin/arp/arp.c882
1 files changed, 882 insertions, 0 deletions
diff --git a/usr.sbin/arp/arp.c b/usr.sbin/arp/arp.c
new file mode 100644
index 0000000..eefde75
--- /dev/null
+++ b/usr.sbin/arp/arp.c
@@ -0,0 +1,882 @@
+/*
+ * Copyright (c) 1984, 1993
+ * The Regents of the University of California. All rights reserved.
+ *
+ * This code is derived from software contributed to Berkeley by
+ * Sun Microsystems, Inc.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 4. Neither the name of the University nor the names of its contributors
+ * may be used to endorse or promote products derived from this software
+ * without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#if 0
+#ifndef lint
+static char const copyright[] =
+"@(#) Copyright (c) 1984, 1993\n\
+ The Regents of the University of California. All rights reserved.\n";
+#endif /* not lint */
+
+#ifndef lint
+static char const sccsid[] = "@(#)from: arp.c 8.2 (Berkeley) 1/2/94";
+#endif /* not lint */
+#endif
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+/*
+ * arp - display, set, and delete arp table entries
+ */
+
+
+#include <sys/param.h>
+#include <sys/file.h>
+#include <sys/socket.h>
+#include <sys/sockio.h>
+#include <sys/sysctl.h>
+#include <sys/ioctl.h>
+#include <sys/time.h>
+
+#include <net/if.h>
+#include <net/if_dl.h>
+#include <net/if_types.h>
+#include <net/route.h>
+#include <net/iso88025.h>
+
+#include <netinet/in.h>
+#include <netinet/if_ether.h>
+
+#include <arpa/inet.h>
+
+#include <ctype.h>
+#include <err.h>
+#include <errno.h>
+#include <netdb.h>
+#include <nlist.h>
+#include <paths.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <strings.h>
+#include <unistd.h>
+
+typedef void (action_fn)(struct sockaddr_dl *sdl,
+ struct sockaddr_in *s_in, struct rt_msghdr *rtm);
+
+static int search(u_long addr, action_fn *action);
+static action_fn print_entry;
+static action_fn nuke_entry;
+
+static int delete(char *host);
+static void usage(void);
+static int set(int argc, char **argv);
+static int get(char *host);
+static int file(char *name);
+static struct rt_msghdr *rtmsg(int cmd,
+ struct sockaddr_in *dst, struct sockaddr_dl *sdl);
+static int get_ether_addr(in_addr_t ipaddr, struct ether_addr *hwaddr);
+static struct sockaddr_in *getaddr(char *host);
+static int valid_type(int type);
+
+static int nflag; /* no reverse dns lookups */
+static char *rifname;
+
+static time_t expire_time;
+static int flags, doing_proxy;
+
+struct if_nameindex *ifnameindex;
+
+/* which function we're supposed to do */
+#define F_GET 1
+#define F_SET 2
+#define F_FILESET 3
+#define F_REPLACE 4
+#define F_DELETE 5
+
+#define SETFUNC(f) { if (func) usage(); func = (f); }
+
+int
+main(int argc, char *argv[])
+{
+ int ch, func = 0;
+ int rtn = 0;
+ int aflag = 0; /* do it for all entries */
+
+ while ((ch = getopt(argc, argv, "andfsSi:")) != -1)
+ switch(ch) {
+ case 'a':
+ aflag = 1;
+ break;
+ case 'd':
+ SETFUNC(F_DELETE);
+ break;
+ case 'n':
+ nflag = 1;
+ break;
+ case 'S':
+ SETFUNC(F_REPLACE);
+ break;
+ case 's':
+ SETFUNC(F_SET);
+ break;
+ case 'f' :
+ SETFUNC(F_FILESET);
+ break;
+ case 'i':
+ rifname = optarg;
+ break;
+ case '?':
+ default:
+ usage();
+ }
+ argc -= optind;
+ argv += optind;
+
+ if (!func)
+ func = F_GET;
+ if (rifname) {
+ if (func != F_GET && !(func == F_DELETE && aflag))
+ errx(1, "-i not applicable to this operation");
+ if (if_nametoindex(rifname) == 0) {
+ if (errno == ENXIO)
+ errx(1, "interface %s does not exist", rifname);
+ else
+ err(1, "if_nametoindex(%s)", rifname);
+ }
+ }
+ switch (func) {
+ case F_GET:
+ if (aflag) {
+ if (argc != 0)
+ usage();
+ search(0, print_entry);
+ } else {
+ if (argc != 1)
+ usage();
+ rtn = get(argv[0]);
+ }
+ break;
+ case F_SET:
+ case F_REPLACE:
+ if (argc < 2 || argc > 6)
+ usage();
+ if (func == F_REPLACE)
+ (void)delete(argv[0]);
+ rtn = set(argc, argv) ? 1 : 0;
+ break;
+ case F_DELETE:
+ if (aflag) {
+ if (argc != 0)
+ usage();
+ search(0, nuke_entry);
+ } else {
+ if (argc != 1)
+ usage();
+ rtn = delete(argv[0]);
+ }
+ break;
+ case F_FILESET:
+ if (argc != 1)
+ usage();
+ rtn = file(argv[0]);
+ break;
+ }
+
+ if (ifnameindex != NULL)
+ if_freenameindex(ifnameindex);
+
+ return (rtn);
+}
+
+/*
+ * Process a file to set standard arp entries
+ */
+static int
+file(char *name)
+{
+ FILE *fp;
+ int i, retval;
+ char line[100], arg[5][50], *args[5], *p;
+
+ if ((fp = fopen(name, "r")) == NULL)
+ err(1, "cannot open %s", name);
+ args[0] = &arg[0][0];
+ args[1] = &arg[1][0];
+ args[2] = &arg[2][0];
+ args[3] = &arg[3][0];
+ args[4] = &arg[4][0];
+ retval = 0;
+ while(fgets(line, sizeof(line), fp) != NULL) {
+ if ((p = strchr(line, '#')) != NULL)
+ *p = '\0';
+ for (p = line; isblank(*p); p++);
+ if (*p == '\n' || *p == '\0')
+ continue;
+ i = sscanf(p, "%49s %49s %49s %49s %49s", arg[0], arg[1],
+ arg[2], arg[3], arg[4]);
+ if (i < 2) {
+ warnx("bad line: %s", line);
+ retval = 1;
+ continue;
+ }
+ if (set(i, args))
+ retval = 1;
+ }
+ fclose(fp);
+ return (retval);
+}
+
+/*
+ * Given a hostname, fills up a (static) struct sockaddr_in with
+ * the address of the host and returns a pointer to the
+ * structure.
+ */
+static struct sockaddr_in *
+getaddr(char *host)
+{
+ struct hostent *hp;
+ static struct sockaddr_in reply;
+
+ bzero(&reply, sizeof(reply));
+ reply.sin_len = sizeof(reply);
+ reply.sin_family = AF_INET;
+ reply.sin_addr.s_addr = inet_addr(host);
+ if (reply.sin_addr.s_addr == INADDR_NONE) {
+ if (!(hp = gethostbyname(host))) {
+ warnx("%s: %s", host, hstrerror(h_errno));
+ return (NULL);
+ }
+ bcopy((char *)hp->h_addr, (char *)&reply.sin_addr,
+ sizeof reply.sin_addr);
+ }
+ return (&reply);
+}
+
+/*
+ * Returns true if the type is a valid one for ARP.
+ */
+static int
+valid_type(int type)
+{
+
+ switch (type) {
+ case IFT_ETHER:
+ case IFT_FDDI:
+ case IFT_INFINIBAND:
+ case IFT_ISO88023:
+ case IFT_ISO88024:
+ case IFT_ISO88025:
+ case IFT_L2VLAN:
+ case IFT_BRIDGE:
+ return (1);
+ default:
+ return (0);
+ }
+}
+
+/*
+ * Set an individual arp entry
+ */
+static int
+set(int argc, char **argv)
+{
+ struct sockaddr_in *addr;
+ struct sockaddr_in *dst; /* what are we looking for */
+ struct sockaddr_dl *sdl;
+ struct rt_msghdr *rtm;
+ struct ether_addr *ea;
+ char *host = argv[0], *eaddr = argv[1];
+ struct sockaddr_dl sdl_m;
+
+ argc -= 2;
+ argv += 2;
+
+ bzero(&sdl_m, sizeof(sdl_m));
+ sdl_m.sdl_len = sizeof(sdl_m);
+ sdl_m.sdl_family = AF_LINK;
+
+ dst = getaddr(host);
+ if (dst == NULL)
+ return (1);
+ doing_proxy = flags = expire_time = 0;
+ while (argc-- > 0) {
+ if (strncmp(argv[0], "temp", 4) == 0) {
+ struct timespec tp;
+ int max_age;
+ size_t len = sizeof(max_age);
+
+ clock_gettime(CLOCK_MONOTONIC, &tp);
+ if (sysctlbyname("net.link.ether.inet.max_age",
+ &max_age, &len, NULL, 0) != 0)
+ err(1, "sysctlbyname");
+ expire_time = tp.tv_sec + max_age;
+ } else if (strncmp(argv[0], "pub", 3) == 0) {
+ flags |= RTF_ANNOUNCE;
+ doing_proxy = 1;
+ if (argc && strncmp(argv[1], "only", 3) == 0) {
+ /*
+ * Compatibility: in pre FreeBSD 8 times
+ * the "only" keyword used to mean that
+ * an ARP entry should be announced, but
+ * not installed into routing table.
+ */
+ argc--; argv++;
+ }
+ } else if (strncmp(argv[0], "blackhole", 9) == 0) {
+ if (flags & RTF_REJECT) {
+ printf("Choose one of blackhole or reject, not both.\n");
+ }
+ flags |= RTF_BLACKHOLE;
+ } else if (strncmp(argv[0], "reject", 6) == 0) {
+ if (flags & RTF_BLACKHOLE) {
+ printf("Choose one of blackhole or reject, not both.\n");
+ }
+ flags |= RTF_REJECT;
+ } else if (strncmp(argv[0], "trail", 5) == 0) {
+ /* XXX deprecated and undocumented feature */
+ printf("%s: Sending trailers is no longer supported\n",
+ host);
+ }
+ argv++;
+ }
+ ea = (struct ether_addr *)LLADDR(&sdl_m);
+ if (doing_proxy && !strcmp(eaddr, "auto")) {
+ if (!get_ether_addr(dst->sin_addr.s_addr, ea)) {
+ printf("no interface found for %s\n",
+ inet_ntoa(dst->sin_addr));
+ return (1);
+ }
+ sdl_m.sdl_alen = ETHER_ADDR_LEN;
+ } else {
+ struct ether_addr *ea1 = ether_aton(eaddr);
+
+ if (ea1 == NULL) {
+ warnx("invalid Ethernet address '%s'", eaddr);
+ return (1);
+ } else {
+ *ea = *ea1;
+ sdl_m.sdl_alen = ETHER_ADDR_LEN;
+ }
+ }
+
+ /*
+ * In the case a proxy-arp entry is being added for
+ * a remote end point, the RTF_ANNOUNCE flag in the
+ * RTM_GET command is an indication to the kernel
+ * routing code that the interface associated with
+ * the prefix route covering the local end of the
+ * PPP link should be returned, on which ARP applies.
+ */
+ rtm = rtmsg(RTM_GET, dst, &sdl_m);
+ if (rtm == NULL) {
+ warn("%s", host);
+ return (1);
+ }
+ addr = (struct sockaddr_in *)(rtm + 1);
+ sdl = (struct sockaddr_dl *)(SA_SIZE(addr) + (char *)addr);
+
+ if ((sdl->sdl_family != AF_LINK) ||
+ (rtm->rtm_flags & RTF_GATEWAY) ||
+ !valid_type(sdl->sdl_type)) {
+ printf("cannot intuit interface index and type for %s\n", host);
+ return (1);
+ }
+ sdl_m.sdl_type = sdl->sdl_type;
+ sdl_m.sdl_index = sdl->sdl_index;
+ return (rtmsg(RTM_ADD, dst, &sdl_m) == NULL);
+}
+
+/*
+ * Display an individual arp entry
+ */
+static int
+get(char *host)
+{
+ struct sockaddr_in *addr;
+
+ addr = getaddr(host);
+ if (addr == NULL)
+ return (1);
+ if (0 == search(addr->sin_addr.s_addr, print_entry)) {
+ printf("%s (%s) -- no entry",
+ host, inet_ntoa(addr->sin_addr));
+ if (rifname)
+ printf(" on %s", rifname);
+ printf("\n");
+ return (1);
+ }
+ return (0);
+}
+
+/*
+ * Delete an arp entry
+ */
+static int
+delete(char *host)
+{
+ struct sockaddr_in *addr, *dst;
+ struct rt_msghdr *rtm;
+ struct sockaddr_dl *sdl;
+ struct sockaddr_dl sdl_m;
+
+ dst = getaddr(host);
+ if (dst == NULL)
+ return (1);
+
+ /*
+ * Perform a regular entry delete first.
+ */
+ flags &= ~RTF_ANNOUNCE;
+
+ /*
+ * setup the data structure to notify the kernel
+ * it is the ARP entry the RTM_GET is interested
+ * in
+ */
+ bzero(&sdl_m, sizeof(sdl_m));
+ sdl_m.sdl_len = sizeof(sdl_m);
+ sdl_m.sdl_family = AF_LINK;
+
+ for (;;) { /* try twice */
+ rtm = rtmsg(RTM_GET, dst, &sdl_m);
+ if (rtm == NULL) {
+ warn("%s", host);
+ return (1);
+ }
+ addr = (struct sockaddr_in *)(rtm + 1);
+ sdl = (struct sockaddr_dl *)(SA_SIZE(addr) + (char *)addr);
+
+ /*
+ * With the new L2/L3 restructure, the route
+ * returned is a prefix route. The important
+ * piece of information from the previous
+ * RTM_GET is the interface index. In the
+ * case of ECMP, the kernel will traverse
+ * the route group for the given entry.
+ */
+ if (sdl->sdl_family == AF_LINK &&
+ !(rtm->rtm_flags & RTF_GATEWAY) &&
+ valid_type(sdl->sdl_type) ) {
+ addr->sin_addr.s_addr = dst->sin_addr.s_addr;
+ break;
+ }
+
+ /*
+ * Regualar entry delete failed, now check if there
+ * is a proxy-arp entry to remove.
+ */
+ if (flags & RTF_ANNOUNCE) {
+ fprintf(stderr, "delete: cannot locate %s\n",host);
+ return (1);
+ }
+
+ flags |= RTF_ANNOUNCE;
+ }
+ rtm->rtm_flags |= RTF_LLDATA;
+ if (rtmsg(RTM_DELETE, dst, NULL) != NULL) {
+ printf("%s (%s) deleted\n", host, inet_ntoa(addr->sin_addr));
+ return (0);
+ }
+ return (1);
+}
+
+
+/*
+ * Search the arp table and do some action on matching entries
+ */
+static int
+search(u_long addr, action_fn *action)
+{
+ int mib[6];
+ size_t needed;
+ char *lim, *buf, *next;
+ struct rt_msghdr *rtm;
+ struct sockaddr_in *sin2;
+ struct sockaddr_dl *sdl;
+ char ifname[IF_NAMESIZE];
+ int st, found_entry = 0;
+
+ mib[0] = CTL_NET;
+ mib[1] = PF_ROUTE;
+ mib[2] = 0;
+ mib[3] = AF_INET;
+ mib[4] = NET_RT_FLAGS;
+#ifdef RTF_LLINFO
+ mib[5] = RTF_LLINFO;
+#else
+ mib[5] = 0;
+#endif
+ if (sysctl(mib, 6, NULL, &needed, NULL, 0) < 0)
+ err(1, "route-sysctl-estimate");
+ if (needed == 0) /* empty table */
+ return 0;
+ buf = NULL;
+ for (;;) {
+ buf = reallocf(buf, needed);
+ if (buf == NULL)
+ errx(1, "could not reallocate memory");
+ st = sysctl(mib, 6, buf, &needed, NULL, 0);
+ if (st == 0 || errno != ENOMEM)
+ break;
+ needed += needed / 8;
+ }
+ if (st == -1)
+ err(1, "actual retrieval of routing table");
+ lim = buf + needed;
+ for (next = buf; next < lim; next += rtm->rtm_msglen) {
+ rtm = (struct rt_msghdr *)next;
+ sin2 = (struct sockaddr_in *)(rtm + 1);
+ sdl = (struct sockaddr_dl *)((char *)sin2 + SA_SIZE(sin2));
+ if (rifname && if_indextoname(sdl->sdl_index, ifname) &&
+ strcmp(ifname, rifname))
+ continue;
+ if (addr) {
+ if (addr != sin2->sin_addr.s_addr)
+ continue;
+ found_entry = 1;
+ }
+ (*action)(sdl, sin2, rtm);
+ }
+ free(buf);
+ return (found_entry);
+}
+
+/*
+ * Display an arp entry
+ */
+
+static void
+print_entry(struct sockaddr_dl *sdl,
+ struct sockaddr_in *addr, struct rt_msghdr *rtm)
+{
+ const char *host;
+ struct hostent *hp;
+ struct iso88025_sockaddr_dl_data *trld;
+ struct if_nameindex *p;
+ int seg;
+
+ if (ifnameindex == NULL)
+ if ((ifnameindex = if_nameindex()) == NULL)
+ err(1, "cannot retrieve interface names");
+
+ if (nflag == 0)
+ hp = gethostbyaddr((caddr_t)&(addr->sin_addr),
+ sizeof addr->sin_addr, AF_INET);
+ else
+ hp = 0;
+ if (hp)
+ host = hp->h_name;
+ else {
+ host = "?";
+ if (h_errno == TRY_AGAIN)
+ nflag = 1;
+ }
+ printf("%s (%s) at ", host, inet_ntoa(addr->sin_addr));
+ if (sdl->sdl_alen) {
+ if ((sdl->sdl_type == IFT_ETHER ||
+ sdl->sdl_type == IFT_L2VLAN ||
+ sdl->sdl_type == IFT_BRIDGE) &&
+ sdl->sdl_alen == ETHER_ADDR_LEN)
+ printf("%s", ether_ntoa((struct ether_addr *)LLADDR(sdl)));
+ else {
+ int n = sdl->sdl_nlen > 0 ? sdl->sdl_nlen + 1 : 0;
+
+ printf("%s", link_ntoa(sdl) + n);
+ }
+ } else
+ printf("(incomplete)");
+
+ for (p = ifnameindex; p && ifnameindex->if_index &&
+ ifnameindex->if_name; p++) {
+ if (p->if_index == sdl->sdl_index) {
+ printf(" on %s", p->if_name);
+ break;
+ }
+ }
+
+ if (rtm->rtm_rmx.rmx_expire == 0)
+ printf(" permanent");
+ else {
+ static struct timespec tp;
+ if (tp.tv_sec == 0)
+ clock_gettime(CLOCK_MONOTONIC, &tp);
+ if ((expire_time = rtm->rtm_rmx.rmx_expire - tp.tv_sec) > 0)
+ printf(" expires in %d seconds", (int)expire_time);
+ else
+ printf(" expired");
+ }
+ if (rtm->rtm_flags & RTF_ANNOUNCE)
+ printf(" published");
+ switch(sdl->sdl_type) {
+ case IFT_ETHER:
+ printf(" [ethernet]");
+ break;
+ case IFT_ISO88025:
+ printf(" [token-ring]");
+ trld = SDL_ISO88025(sdl);
+ if (trld->trld_rcf != 0) {
+ printf(" rt=%x", ntohs(trld->trld_rcf));
+ for (seg = 0;
+ seg < ((TR_RCF_RIFLEN(trld->trld_rcf) - 2 ) / 2);
+ seg++)
+ printf(":%x", ntohs(*(trld->trld_route[seg])));
+ }
+ break;
+ case IFT_FDDI:
+ printf(" [fddi]");
+ break;
+ case IFT_ATM:
+ printf(" [atm]");
+ break;
+ case IFT_L2VLAN:
+ printf(" [vlan]");
+ break;
+ case IFT_IEEE1394:
+ printf(" [firewire]");
+ break;
+ case IFT_BRIDGE:
+ printf(" [bridge]");
+ break;
+ case IFT_INFINIBAND:
+ printf(" [infiniband]");
+ break;
+ default:
+ break;
+ }
+
+ printf("\n");
+
+}
+
+/*
+ * Nuke an arp entry
+ */
+static void
+nuke_entry(struct sockaddr_dl *sdl __unused,
+ struct sockaddr_in *addr, struct rt_msghdr *rtm)
+{
+ char ip[20];
+
+ if (rtm->rtm_flags & RTF_PINNED)
+ return;
+
+ snprintf(ip, sizeof(ip), "%s", inet_ntoa(addr->sin_addr));
+ delete(ip);
+}
+
+static void
+usage(void)
+{
+ fprintf(stderr, "%s\n%s\n%s\n%s\n%s\n%s\n%s\n",
+ "usage: arp [-n] [-i interface] hostname",
+ " arp [-n] [-i interface] -a",
+ " arp -d hostname [pub]",
+ " arp -d [-i interface] -a",
+ " arp -s hostname ether_addr [temp] [reject | blackhole] [pub [only]]",
+ " arp -S hostname ether_addr [temp] [reject | blackhole] [pub [only]]",
+ " arp -f filename");
+ exit(1);
+}
+
+static struct rt_msghdr *
+rtmsg(int cmd, struct sockaddr_in *dst, struct sockaddr_dl *sdl)
+{
+ static int seq;
+ int rlen;
+ int l;
+ struct sockaddr_in so_mask, *som = &so_mask;
+ static int s = -1;
+ static pid_t pid;
+
+ static struct {
+ struct rt_msghdr m_rtm;
+ char m_space[512];
+ } m_rtmsg;
+
+ struct rt_msghdr *rtm = &m_rtmsg.m_rtm;
+ char *cp = m_rtmsg.m_space;
+
+ if (s < 0) { /* first time: open socket, get pid */
+ s = socket(PF_ROUTE, SOCK_RAW, 0);
+ if (s < 0)
+ err(1, "socket");
+ pid = getpid();
+ }
+ bzero(&so_mask, sizeof(so_mask));
+ so_mask.sin_len = 8;
+ so_mask.sin_addr.s_addr = 0xffffffff;
+
+ errno = 0;
+ /*
+ * XXX RTM_DELETE relies on a previous RTM_GET to fill the buffer
+ * appropriately.
+ */
+ if (cmd == RTM_DELETE)
+ goto doit;
+ bzero((char *)&m_rtmsg, sizeof(m_rtmsg));
+ rtm->rtm_flags = flags;
+ rtm->rtm_version = RTM_VERSION;
+
+ switch (cmd) {
+ default:
+ errx(1, "internal wrong cmd");
+ case RTM_ADD:
+ rtm->rtm_addrs |= RTA_GATEWAY;
+ rtm->rtm_rmx.rmx_expire = expire_time;
+ rtm->rtm_inits = RTV_EXPIRE;
+ rtm->rtm_flags |= (RTF_HOST | RTF_STATIC | RTF_LLDATA);
+ if (doing_proxy) {
+ rtm->rtm_addrs |= RTA_NETMASK;
+ rtm->rtm_flags &= ~RTF_HOST;
+ }
+ /* FALLTHROUGH */
+ case RTM_GET:
+ rtm->rtm_addrs |= RTA_DST;
+ }
+#define NEXTADDR(w, s) \
+ do { \
+ if ((s) != NULL && rtm->rtm_addrs & (w)) { \
+ bcopy((s), cp, sizeof(*(s))); \
+ cp += SA_SIZE(s); \
+ } \
+ } while (0)
+
+ NEXTADDR(RTA_DST, dst);
+ NEXTADDR(RTA_GATEWAY, sdl);
+ NEXTADDR(RTA_NETMASK, som);
+
+ rtm->rtm_msglen = cp - (char *)&m_rtmsg;
+doit:
+ l = rtm->rtm_msglen;
+ rtm->rtm_seq = ++seq;
+ rtm->rtm_type = cmd;
+ if ((rlen = write(s, (char *)&m_rtmsg, l)) < 0) {
+ if (errno != ESRCH || cmd != RTM_DELETE) {
+ warn("writing to routing socket");
+ return (NULL);
+ }
+ }
+ do {
+ l = read(s, (char *)&m_rtmsg, sizeof(m_rtmsg));
+ } while (l > 0 && (rtm->rtm_seq != seq || rtm->rtm_pid != pid));
+ if (l < 0)
+ warn("read from routing socket");
+ return (rtm);
+}
+
+/*
+ * get_ether_addr - get the hardware address of an interface on the
+ * the same subnet as ipaddr.
+ */
+#define MAX_IFS 32
+
+static int
+get_ether_addr(in_addr_t ipaddr, struct ether_addr *hwaddr)
+{
+ struct ifreq *ifr, *ifend, *ifp;
+ in_addr_t ina, mask;
+ struct sockaddr_dl *dla;
+ struct ifreq ifreq;
+ struct ifconf ifc;
+ struct ifreq ifs[MAX_IFS];
+ int sock;
+ int retval = 0;
+
+ sock = socket(AF_INET, SOCK_DGRAM, 0);
+ if (sock < 0)
+ err(1, "socket");
+
+ ifc.ifc_len = sizeof(ifs);
+ ifc.ifc_req = ifs;
+ if (ioctl(sock, SIOCGIFCONF, &ifc) < 0) {
+ warnx("ioctl(SIOCGIFCONF)");
+ goto done;
+ }
+
+#define NEXTIFR(i) \
+ ((struct ifreq *)((char *)&(i)->ifr_addr \
+ + MAX((i)->ifr_addr.sa_len, sizeof((i)->ifr_addr))) )
+
+ /*
+ * Scan through looking for an interface with an Internet
+ * address on the same subnet as `ipaddr'.
+ */
+ ifend = (struct ifreq *)(ifc.ifc_buf + ifc.ifc_len);
+ for (ifr = ifc.ifc_req; ifr < ifend; ifr = NEXTIFR(ifr) ) {
+ if (ifr->ifr_addr.sa_family != AF_INET)
+ continue;
+ strncpy(ifreq.ifr_name, ifr->ifr_name,
+ sizeof(ifreq.ifr_name));
+ ifreq.ifr_addr = ifr->ifr_addr;
+ /*
+ * Check that the interface is up,
+ * and not point-to-point or loopback.
+ */
+ if (ioctl(sock, SIOCGIFFLAGS, &ifreq) < 0)
+ continue;
+ if ((ifreq.ifr_flags &
+ (IFF_UP|IFF_BROADCAST|IFF_POINTOPOINT|
+ IFF_LOOPBACK|IFF_NOARP))
+ != (IFF_UP|IFF_BROADCAST))
+ continue;
+ /*
+ * Get its netmask and check that it's on
+ * the right subnet.
+ */
+ if (ioctl(sock, SIOCGIFNETMASK, &ifreq) < 0)
+ continue;
+ mask = ((struct sockaddr_in *)
+ &ifreq.ifr_addr)->sin_addr.s_addr;
+ ina = ((struct sockaddr_in *)
+ &ifr->ifr_addr)->sin_addr.s_addr;
+ if ((ipaddr & mask) == (ina & mask))
+ break; /* ok, we got it! */
+ }
+
+ if (ifr >= ifend)
+ goto done;
+
+ /*
+ * Now scan through again looking for a link-level address
+ * for this interface.
+ */
+ ifp = ifr;
+ for (ifr = ifc.ifc_req; ifr < ifend; ifr = NEXTIFR(ifr))
+ if (strcmp(ifp->ifr_name, ifr->ifr_name) == 0 &&
+ ifr->ifr_addr.sa_family == AF_LINK)
+ break;
+ if (ifr >= ifend)
+ goto done;
+ /*
+ * Found the link-level address - copy it out
+ */
+ dla = (struct sockaddr_dl *) &ifr->ifr_addr;
+ memcpy(hwaddr, LLADDR(dla), dla->sdl_alen);
+ printf("using interface %s for proxy with address ",
+ ifp->ifr_name);
+ printf("%s\n", ether_ntoa(hwaddr));
+ retval = dla->sdl_alen;
+done:
+ close(sock);
+ return (retval);
+}
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