/*
 * The mrouted program is covered by the license in the accompanying file
 * named "LICENSE".  Use of the mrouted program represents acceptance of
 * the terms and conditions listed in that file.
 *
 * The mrouted program is COPYRIGHT 1989 by The Board of Trustees of
 * Leland Stanford Junior University.
 *
 *
 * icmp.c,v 3.8.4.2 1998/01/06 01:57:42 fenner Exp
 */

#include "defs.h"

#ifndef lint
static char rcsid[] = "@(#) $Id: \
icmp.c,v 3.8.4.2 1998/01/06 01:57:42 fenner Exp $";
#endif

static int	icmp_socket;

static void	icmp_handler __P((int, fd_set *));
static char *	icmp_name __P((struct icmp *));

void
init_icmp()
{
    if ((icmp_socket = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP)) < 0)
	log(LOG_ERR, errno, "ICMP socket");

    register_input_handler(icmp_socket, icmp_handler);

    IF_DEBUG(DEBUG_ICMP)
    log(LOG_DEBUG, 0, "registering icmp socket fd %d\n", icmp_socket);
}

static void
icmp_handler(fd, rfds)
    int fd;
    fd_set *rfds;
{
    u_char icmp_buf[RECV_BUF_SIZE];
    struct sockaddr_in from;
    int fromlen, recvlen, iphdrlen, ipdatalen;
    struct icmp *icmp;
    struct ip *ip;
    vifi_t i;
    struct uvif *v;
    u_int32 src;

    fromlen = sizeof(from);
    recvlen = recvfrom(icmp_socket, icmp_buf, RECV_BUF_SIZE, 0,
			    (struct sockaddr *)&from, &fromlen);
    if (recvlen < 0) {
	if (errno != EINTR)
	    log(LOG_WARNING, errno, "icmp_socket recvfrom");
	return;
    }
    ip = (struct ip *)icmp_buf;
    iphdrlen = ip->ip_hl << 2;
#ifdef RAW_INPUT_IS_RAW
    ipdatalen = ntohs(ip->ip_len) - iphdrlen;
#else
    ipdatalen = ip->ip_len;
#endif
    if (iphdrlen + ipdatalen != recvlen) {
	IF_DEBUG(DEBUG_ICMP)
	log(LOG_DEBUG, 0, "hdr %d data %d != rcv %d", iphdrlen, ipdatalen, recvlen);
	/* Malformed ICMP, just return. */
	return;
    }
    if (ipdatalen < ICMP_MINLEN + sizeof(struct ip)) {
	/* Not enough data for us to be interested in it. */
	return;
    }
    src = ip->ip_src.s_addr;
    icmp = (struct icmp *)(icmp_buf + iphdrlen);
    IF_DEBUG(DEBUG_ICMP)
    log(LOG_DEBUG, 0, "got ICMP type %d from %s",
	icmp->icmp_type, inet_fmt(src, s1));
    /*
     * Eventually:
     * have registry of ICMP listeners, by type, code and ICMP_ID
     * (and maybe fields of the original packet too -- maybe need a
     * generalized packet filter!) to allow ping and traceroute
     * from the monitoring tool.
     */
    switch (icmp->icmp_type) {
	case ICMP_UNREACH:
	case ICMP_TIMXCEED:
	    /* Look at returned packet to see if it's us sending on a tunnel */
	    ip = &icmp->icmp_ip;
	    if (ip->ip_p != IPPROTO_IGMP && ip->ip_p != IPPROTO_IPIP)
		return;
	    for (v = uvifs, i = 0; i < numvifs; v++, i++) {
		if (ip->ip_src.s_addr == v->uv_lcl_addr &&
		    ip->ip_dst.s_addr == v->uv_dst_addr) {
		    char *p;
		    int n;
		    /*
		     * I sent this packet on this vif.
		     */
		    n = ++v->uv_icmp_warn;
		    while (n && !(n & 1))
			n >>= 1;
		    if (n == 1 && ((p = icmp_name(icmp)) != NULL))
			log(LOG_WARNING, 0, "Received ICMP %s from %s %s %s on vif %d",
			    p, inet_fmt(src, s1), "for traffic sent to",
			    inet_fmt(ip->ip_dst.s_addr, s2),
			    i);

		    break;
		}
	    }
	    break;
    }
}

/*
 * Return NULL for ICMP informational messages.
 * Return string describing the error for ICMP errors.
 */
static char *
icmp_name(icmp)
    struct icmp *icmp;
{
    static char retval[30];

    switch (icmp->icmp_type) {
	case ICMP_UNREACH:
	    switch (icmp->icmp_code) {
		case ICMP_UNREACH_NET:
		    return "network unreachable";
		case ICMP_UNREACH_HOST:
		    return "host unreachable";
		case ICMP_UNREACH_PROTOCOL:
		    return "protocol unreachable";
		case ICMP_UNREACH_PORT:
		    return "port unreachable";
		case ICMP_UNREACH_NEEDFRAG:
		    return "needs fragmentation";
		case ICMP_UNREACH_SRCFAIL:
		    return "source route failed";
#ifndef ICMP_UNREACH_NET_UNKNOWN
#define ICMP_UNREACH_NET_UNKNOWN	6
#endif
		case ICMP_UNREACH_NET_UNKNOWN:
		    return "network unknown";
#ifndef ICMP_UNREACH_HOST_UNKNOWN
#define ICMP_UNREACH_HOST_UNKNOWN	7
#endif
		case ICMP_UNREACH_HOST_UNKNOWN:
		    return "host unknown";
#ifndef ICMP_UNREACH_ISOLATED
#define ICMP_UNREACH_ISOLATED		8
#endif
		case ICMP_UNREACH_ISOLATED:
		    return "source host isolated";
#ifndef ICMP_UNREACH_NET_PROHIB
#define ICMP_UNREACH_NET_PROHIB		9
#endif
		case ICMP_UNREACH_NET_PROHIB:
		    return "network access prohibited";
#ifndef ICMP_UNREACH_HOST_PROHIB
#define ICMP_UNREACH_HOST_PROHIB	10
#endif
		case ICMP_UNREACH_HOST_PROHIB:
		    return "host access prohibited";
#ifndef ICMP_UNREACH_TOSNET
#define ICMP_UNREACH_TOSNET		11
#endif
		case ICMP_UNREACH_TOSNET:
		    return "bad TOS for net";
#ifndef ICMP_UNREACH_TOSHOST
#define ICMP_UNREACH_TOSHOST		12
#endif
		case ICMP_UNREACH_TOSHOST:
		    return "bad TOS for host";
#ifndef ICMP_UNREACH_FILTER_PROHIB
#define ICMP_UNREACH_FILTER_PROHIB	13
#endif
		case ICMP_UNREACH_FILTER_PROHIB:
		    return "prohibited by filter";
#ifndef ICMP_UNREACH_HOST_PRECEDENCE
#define ICMP_UNREACH_HOST_PRECEDENCE	14
#endif
		case ICMP_UNREACH_HOST_PRECEDENCE:
		    return "host precedence violation";
#ifndef ICMP_UNREACH_PRECEDENCE_CUTOFF
#define ICMP_UNREACH_PRECEDENCE_CUTOFF	15
#endif
		case ICMP_UNREACH_PRECEDENCE_CUTOFF:
		    return "precedence cutoff";
		default:
		    sprintf(retval, "unreachable code %d", icmp->icmp_code);
		    return retval;
	    }
	case ICMP_SOURCEQUENCH:
	    return "source quench";
	case ICMP_REDIRECT:
	    return NULL;	/* XXX */
	case ICMP_TIMXCEED:
	    switch (icmp->icmp_code) {
		case ICMP_TIMXCEED_INTRANS:
		    return "time exceeded in transit";
		case ICMP_TIMXCEED_REASS:
		    return "time exceeded in reassembly";
		default:
		    sprintf(retval, "time exceeded code %d", icmp->icmp_code);
		    return retval;
	    }
	case ICMP_PARAMPROB:
	    switch (icmp->icmp_code) {
#ifndef ICMP_PARAMPROB_OPTABSENT
#define ICMP_PARAMPROB_OPTABSENT	1
#endif
		case ICMP_PARAMPROB_OPTABSENT:
		    return "required option absent";
		default:
		    sprintf(retval, "parameter problem code %d", icmp->icmp_code);
		    return retval;
	    }
    }
    return NULL;
}