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From fed8c3db10bc9d3a1e799a774924c00522595d0c Mon Sep 17 00:00:00 2001
From: Evgeny Yurchenko <evg.yurch@rogers.com>
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
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