sbin/mrouted/igmp.c

/*
 * 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.
 *
 *
 * $Id: igmp.c,v 1.5 1993/06/23 18:47:17 pavel Exp $
 */


#include "defs.h"


/*
 * Exported variables.
 */
char            recv_buf[MAX_IP_PACKET_LEN]; /* input packet buffer         */
char            send_buf[MAX_IP_PACKET_LEN]; /* output packet buffer        */
int             igmp_socket;                 /* socket for all network I/O  */
u_long          allhosts_group;              /* allhosts  addr in net order */
u_long          dvmrp_group;                 /* DVMRP grp addr in net order */


/*
 * Open and initialize the igmp socket, and fill in the non-changing
 * IP header fields in the output packet buffer.
 */
void init_igmp()
{
    struct ip *ip;

    if ((igmp_socket = socket(AF_INET, SOCK_RAW, IPPROTO_IGMP)) < 0)
        log(LOG_ERR, errno, "IGMP socket");

    k_hdr_include(TRUE);        /* include IP header when sending */
    k_set_rcvbuf(48*1024);      /* lots of input buffering        */
    k_set_ttl(1);               /* restrict multicasts to one hop */
    k_set_loop(FALSE);          /* disable multicast loopback     */

    ip         = (struct ip *)send_buf;
    ip->ip_tos = 0;
    ip->ip_off = 0;
    ip->ip_p   = IPPROTO_IGMP;
    ip->ip_ttl = MAXTTL;        /* applies to unicasts only */

    allhosts_group = htonl(INADDR_ALLHOSTS_GROUP);
    dvmrp_group    = htonl(INADDR_DVMRP_GROUP);
}

static char *packet_kind(type, code)
     u_char type, code;
{
    switch (type) {
        case IGMP_HOST_MEMBERSHIP_QUERY:        return "membership query  ";
        case IGMP_HOST_MEMBERSHIP_REPORT:       return "membership report ";
        case IGMP_DVMRP:
          switch (code) {
            case DVMRP_PROBE:                   return "neighbor probe    ";
            case DVMRP_REPORT:                  return "route report      ";
            case DVMRP_ASK_NEIGHBORS:           return "neighbor request  ";
            case DVMRP_NEIGHBORS:               return "neighbor list     ";
            case DVMRP_ASK_NEIGHBORS2:          return "neighbor request 2";
            case DVMRP_NEIGHBORS2:              return "neighbor list 2   ";
            default:                            return "unknown DVMRP msg ";
          }
        default:                                return "unknown IGMP msg  ";
    }
}

/*
 * Process a newly received IGMP packet that is sitting in the input
 * packet buffer.
 */
void accept_igmp(recvlen)
    int recvlen;
{
    register vifi_t vifi;
    register u_long src, dst, group;
    struct ip *ip;
    struct igmp *igmp;
    int ipdatalen, iphdrlen, igmpdatalen;

    if (recvlen < sizeof(struct ip)) {
        log(LOG_WARNING, 0,
            "received packet too short (%u bytes) for IP header", recvlen);
        return;
    }

    ip        = (struct ip *)recv_buf;
    src       = ip->ip_src.s_addr;
    dst       = ip->ip_dst.s_addr;
    iphdrlen  = ip->ip_hl << 2;
    ipdatalen = ip->ip_len;
    if (iphdrlen + ipdatalen != recvlen) {
        log(LOG_WARNING, 0,
            "received packet shorter (%u bytes) than hdr+data length (%u+%u)",
            recvlen, iphdrlen, ipdatalen);
        return;
    }

    igmp        = (struct igmp *)(recv_buf + iphdrlen);
    group       = igmp->igmp_group.s_addr;
    igmpdatalen = ipdatalen - IGMP_MINLEN;
    if (igmpdatalen < 0) {
        log(LOG_WARNING, 0,
            "received IP data field too short (%u bytes) for IGMP, from %s",
            ipdatalen, inet_fmt(src, s1));
        return;
    }

    log(LOG_DEBUG, 0, "RECV %s from %-15s to %s",
        packet_kind(igmp->igmp_type, igmp->igmp_code),
        inet_fmt(src, s1), inet_fmt(dst, s2));

    switch (igmp->igmp_type) {

        case IGMP_HOST_MEMBERSHIP_QUERY:
            return;     /* Answered automatically by the kernel. */

        case IGMP_HOST_MEMBERSHIP_REPORT:
            accept_group_report(src, dst, group);
            return;

        case IGMP_DVMRP:
            switch (igmp->igmp_code) {

                case DVMRP_PROBE:
                    accept_probe(src, dst);
                    return;

                case DVMRP_REPORT:
                    accept_report(src, dst,
                                  (char *)(igmp+1), igmpdatalen);
                    return;

                case DVMRP_ASK_NEIGHBORS:
                    accept_neighbor_request(src, dst);
                    return;

                case DVMRP_ASK_NEIGHBORS2:
                    accept_neighbor_request2(src, dst);
                    return;

                case DVMRP_NEIGHBORS:
                    accept_neighbors(src, dst, (char *)(igmp+1), igmpdatalen,
                                     group);
                    return;

                case DVMRP_NEIGHBORS2:
                    accept_neighbors2(src, dst, (char *)(igmp+1), igmpdatalen,
                                     group);
                    return;

                default:
                    log(LOG_INFO, 0,
                     "ignoring unknown DVMRP message code %u from %s to %s",
                     igmp->igmp_code, inet_fmt(src, s1),
                     inet_fmt(dst, s2));
                    return;
            }

        default:
            log(LOG_INFO, 0,
                "ignoring unknown IGMP message type %u from %s to %s",
                igmp->igmp_type, inet_fmt(src, s1),
                inet_fmt(dst, s2));
            return;
    }
}


/*
 * Construct an IGMP message in the output packet buffer.  The caller may
 * have already placed data in that buffer, of length 'datalen'.  Then send
 * the message from the interface with IP address 'src' to destination 'dst'.
 */
void send_igmp(src, dst, type, code, group, datalen)
    u_long src, dst;
    int type, code;
    u_long group;
    int datalen;
{
    static struct sockaddr_in sdst = {AF_INET};
    struct ip *ip;
    struct igmp *igmp;

    ip                      = (struct ip *)send_buf;
    ip->ip_src.s_addr       = src;
    ip->ip_dst.s_addr       = dst;
    ip->ip_len              = MIN_IP_HEADER_LEN + IGMP_MINLEN + datalen;

    igmp                    = (struct igmp *)(send_buf + MIN_IP_HEADER_LEN);
    igmp->igmp_type         = type;
    igmp->igmp_code         = code;
    igmp->igmp_group.s_addr = group;
    igmp->igmp_cksum        = 0;
    igmp->igmp_cksum        = inet_cksum((u_short *)igmp,
                                         IGMP_MINLEN + datalen);

    if (IN_MULTICAST(ntohl(dst))) k_set_if(src);
    if (dst == allhosts_group) k_set_loop(TRUE);

    sdst.sin_addr.s_addr = dst;
    if (sendto(igmp_socket, send_buf, ip->ip_len, 0,
                        (struct sockaddr *)&sdst, sizeof(sdst)) < 0) {
        if (errno == ENETDOWN) check_vif_state();
        else log(LOG_WARNING, errno, "sendto on %s", inet_fmt(src, s1));
    }

    if (dst == allhosts_group) k_set_loop(FALSE);

    log(LOG_DEBUG, 0, "SENT %s from %-15s to %s",
        packet_kind(type, code), inet_fmt(src, s1), inet_fmt(dst, s2));
}