/*      $NetBSD: igmp.c,v 1.5 1995/12/10 10:07:01 mycroft Exp $ */

/*
 * 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.
 */


#include "defs.h"


/*
 * Exported variables.
 */
char            *recv_buf;                   /* input packet buffer         */
char            *send_buf;                   /* output packet buffer        */
int             igmp_socket;                 /* socket for all network I/O  */
u_int32_t       allhosts_group;              /* All hosts addr in net order */
u_int32_t       allrtrs_group;               /* All-Routers "  in net order */
u_int32_t       dvmrp_group;                 /* DVMRP grp addr in net order */
u_int32_t       dvmrp_genid;                 /* IGMP generation id          */

/*
 * Local function definitions.
 */
/* u_char promoted to u_int */
static char *   packet_kind(u_int type, u_int code);
static int      igmp_log_level(u_int type, u_int code);

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

    recv_buf = malloc(RECV_BUF_SIZE);
    send_buf = malloc(RECV_BUF_SIZE);

    if ((igmp_socket = socket(AF_INET, SOCK_RAW, IPPROTO_IGMP)) == -1)
        logit(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_hl  = sizeof(struct ip) >> 2;
    ip->ip_v   = IPVERSION;
    ip->ip_tos = 0;
    ip->ip_off = htons(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);
    allrtrs_group  = htonl(INADDR_ALLRTRS_GROUP);
}

#define PIM_QUERY        0
#define PIM_REGISTER     1
#define PIM_REGISTER_STOP       2
#define PIM_JOIN_PRUNE   3
#define PIM_RP_REACHABLE 4
#define PIM_ASSERT       5
#define PIM_GRAFT        6
#define PIM_GRAFT_ACK    7

static char *
packet_kind(u_int type, u_int code)
{
    switch (type) {
        case IGMP_HOST_MEMBERSHIP_QUERY:        return "membership query  ";
        case IGMP_v1_HOST_MEMBERSHIP_REPORT:    return "v1 member report  ";
        case IGMP_v2_HOST_MEMBERSHIP_REPORT:    return "v2 member report  ";
        case IGMP_HOST_LEAVE_MESSAGE:           return "leave message     ";
        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   ";
            case DVMRP_PRUNE:                   return "prune message     ";
            case DVMRP_GRAFT:                   return "graft message     ";
            case DVMRP_GRAFT_ACK:               return "graft message ack ";
            case DVMRP_INFO_REQUEST:            return "info request      ";
            case DVMRP_INFO_REPLY:              return "info reply        ";
            default:                            return "unknown DVMRP msg ";
          }
        case IGMP_PIM:
          switch (code) {
            case PIM_QUERY:                     return "PIM Router-Query  ";
            case PIM_REGISTER:                  return "PIM Register      ";
            case PIM_REGISTER_STOP:             return "PIM Register-Stop ";
            case PIM_JOIN_PRUNE:                return "PIM Join/Prune    ";
            case PIM_RP_REACHABLE:              return "PIM RP-Reachable  ";
            case PIM_ASSERT:                    return "PIM Assert        ";
            case PIM_GRAFT:                     return "PIM Graft         ";
            case PIM_GRAFT_ACK:                 return "PIM Graft-Ack     ";
            default:                            return "unknown PIM msg   ";
          }
        case IGMP_MTRACE_QUERY:                 return "IGMP trace query  ";
        case IGMP_MTRACE_REPLY:                 return "IGMP trace reply  ";
        default:                                return "unknown IGMP msg  ";
    }
}

/*
 * Process a newly received IGMP packet that is sitting in the input
 * packet buffer.
 */
void
accept_igmp(int recvlen)
{
    u_int32_t src, dst, group;
    struct ip *ip;
    struct igmp *igmp;
    int ipdatalen, iphdrlen, igmpdatalen;

    if (recvlen < sizeof(struct ip)) {
        logit(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;

    /*
     * this is most likely a message from the kernel indicating that
     * a new src grp pair message has arrived and so, it would be
     * necessary to install a route into the kernel for this.
     */
    if (ip->ip_p == 0) {
        if (src == 0 || dst == 0)
            logit(LOG_WARNING, 0, "kernel request not accurate");
        else
            add_table_entry(src, dst);
        return;
    }

    iphdrlen  = ip->ip_hl << 2;
    ipdatalen = ntohs(ip->ip_len) - iphdrlen;
    if (iphdrlen + ipdatalen != recvlen) {
        logit(LOG_WARNING, 0,
            "received packet from %s shorter (%u bytes) than hdr+data length (%u+%u)",
            inet_fmt(src, s1), recvlen, iphdrlen, ipdatalen);
        return;
    }

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

    logit(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:
            accept_membership_query(src, dst, group, igmp->igmp_code);
            return;

        case IGMP_v1_HOST_MEMBERSHIP_REPORT:
        case IGMP_v2_HOST_MEMBERSHIP_REPORT:
            accept_group_report(src, dst, group, igmp->igmp_type);
            return;

        case IGMP_HOST_LEAVE_MESSAGE:
            accept_leave_message(src, dst, group);
            return;

        case IGMP_DVMRP:
            group = ntohl(group);

            switch (igmp->igmp_code) {
                case DVMRP_PROBE:
                    accept_probe(src, dst,
                                 (char *)(igmp+1), igmpdatalen, group);
                    return;

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

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

                case DVMRP_PRUNE:
                    accept_prune(src, dst, (char *)(igmp+1), igmpdatalen);
                    return;

                case DVMRP_GRAFT:
                    accept_graft(src, dst, (char *)(igmp+1), igmpdatalen);
                    return;

                case DVMRP_GRAFT_ACK:
                    accept_g_ack(src, dst, (char *)(igmp+1), igmpdatalen);
                    return;

                case DVMRP_INFO_REQUEST:
                    accept_info_request(src, dst, (char *)(igmp+1),
                                igmpdatalen);
                    return;

                case DVMRP_INFO_REPLY:
                    accept_info_reply(src, dst, (char *)(igmp+1), igmpdatalen);
                    return;

                default:
                    logit(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;
            }

        case IGMP_PIM:
            return;

        case IGMP_MTRACE_REPLY:
            return;

        case IGMP_MTRACE_QUERY:
            accept_mtrace(src, dst, group, (char *)(igmp+1),
                   igmp->igmp_code, igmpdatalen);
            return;

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

/*
 * Some IGMP messages are more important than others.  This routine
 * determines the logging level at which to log a send error (often
 * "No route to host").  This is important when there is asymmetric
 * reachability and someone is trying to, i.e., mrinfo me periodically.
 */
static int
igmp_log_level(u_int type, u_int code)
{
    switch (type) {
        case IGMP_MTRACE_REPLY:
            return LOG_INFO;

        case IGMP_DVMRP:
          switch (code) {
            case DVMRP_NEIGHBORS:
            case DVMRP_NEIGHBORS2:
                return LOG_INFO;
          }
    }
    return LOG_WARNING;
}

/*
 * 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(u_int32_t src, u_int32_t dst, int type, int code,
    u_int32_t group, int datalen)
{
    struct sockaddr_in sdst;
    struct ip *ip;
    struct igmp *igmp;
    int setloop = 0;

    ip                      = (struct ip *)send_buf;
    ip->ip_src.s_addr       = src;
    ip->ip_dst.s_addr       = dst;
    ip->ip_len              = htons(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_int16_t *)igmp,
                                         IGMP_MINLEN + datalen);

    if (IN_MULTICAST(ntohl(dst))) {
        k_set_if(src);
        if (type != IGMP_DVMRP) {
            setloop = 1;
            k_set_loop(TRUE);
        }
    }

    bzero(&sdst, sizeof(sdst));
    sdst.sin_family = AF_INET;
    sdst.sin_len = sizeof(sdst);
    sdst.sin_addr.s_addr = dst;
    if (sendto(igmp_socket, send_buf, ntohs(ip->ip_len), 0,
                        (struct sockaddr *)&sdst, sizeof(sdst)) == -1) {
        if (errno == ENETDOWN)
            check_vif_state();
        else
            logit(igmp_log_level(type, code), errno,
                "sendto to %s on %s",
                inet_fmt(dst, s1), inet_fmt(src, s2));
    }

    if (setloop)
            k_set_loop(FALSE);

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