From fed8c3db10bc9d3a1e799a774924c00522595d0c Mon Sep 17 00:00:00 2001 From: Evgeny Yurchenko Date: Mon, 4 Jan 2010 05:13:59 +0500 Subject: [PATCH] Send IGMP packets with IP Router Alert option [RFC 2113] included in IP header --- src/igmp.c | 17 ++++++++++++----- src/igmpproxy.h | 1 + 2 files changed, 13 insertions(+), 5 deletions(-) diff --git a/src/igmp.c b/src/igmp.c index a0cd27d..b547688 100644 --- a/src/igmp.c +++ b/src/igmp.c @@ -67,7 +67,7 @@ void initIgmp() { * - Checksum (let the kernel fill it in) */ ip->ip_v = IPVERSION; - ip->ip_hl = sizeof(struct ip) >> 2; + ip->ip_hl = (sizeof(struct ip) + 4) >> 2; /* +4 for Router Alert option */ ip->ip_tos = 0xc0; /* Internet Control */ ip->ip_ttl = MAXTTL; /* applies to unicasts only */ ip->ip_p = IPPROTO_IGMP; @@ -213,7 +213,7 @@ void buildIgmp(uint32_t src, uint32_t dst, int type, int code, uint32_t group, i ip = (struct ip *)send_buf; ip->ip_src.s_addr = src; ip->ip_dst.s_addr = dst; - ip_set_len(ip, MIN_IP_HEADER_LEN + IGMP_MINLEN + datalen); + ip_set_len(ip, IP_HEADER_RAOPT_LEN + IGMP_MINLEN + datalen); if (IN_MULTICAST(ntohl(dst))) { ip->ip_ttl = curttl; @@ -221,13 +221,20 @@ void buildIgmp(uint32_t src, uint32_t dst, int type, int code, uint32_t group, i ip->ip_ttl = MAXTTL; } - igmp = (struct igmp *)(send_buf + MIN_IP_HEADER_LEN); + /* Add Router Alert option */ + ((u_char*)send_buf+MIN_IP_HEADER_LEN)[0] = IPOPT_RA; + ((u_char*)send_buf+MIN_IP_HEADER_LEN)[1] = 0x04; + ((u_char*)send_buf+MIN_IP_HEADER_LEN)[2] = 0x00; + ((u_char*)send_buf+MIN_IP_HEADER_LEN)[3] = 0x00; + + igmp = (struct igmp *)(send_buf + IP_HEADER_RAOPT_LEN); igmp->igmp_type = type; igmp->igmp_code = code; igmp->igmp_group.s_addr = group; igmp->igmp_cksum = 0; igmp->igmp_cksum = inetChksum((u_short *)igmp, - IGMP_MINLEN + datalen); + IP_HEADER_RAOPT_LEN + datalen); + } /* @@ -257,7 +264,7 @@ void sendIgmp(uint32_t src, uint32_t dst, int type, int code, uint32_t group, in #endif sdst.sin_addr.s_addr = dst; if (sendto(MRouterFD, send_buf, - MIN_IP_HEADER_LEN + IGMP_MINLEN + datalen, 0, + IP_HEADER_RAOPT_LEN + IGMP_MINLEN + datalen, 0, (struct sockaddr *)&sdst, sizeof(sdst)) < 0) { if (errno == ENETDOWN) my_log(LOG_ERR, errno, "Sender VIF was down."); diff --git a/src/igmpproxy.h b/src/igmpproxy.h index 0de7791..4df8a79 100644 --- a/src/igmpproxy.h +++ b/src/igmpproxy.h @@ -64,6 +64,7 @@ #define MAX_IP_PACKET_LEN 576 #define MIN_IP_HEADER_LEN 20 #define MAX_IP_HEADER_LEN 60 +#define IP_HEADER_RAOPT_LEN 24 #define MAX_MC_VIFS 32 // !!! check this const in the specific includes -- 1.7.2.5