pimd: Add check for pim join, hello and assert to drop pkts without all-pim-routers dest.

This is as per RFC. This is identified when conformance suite catched join.

RCA:
Packets were processed without checking allowed dest IP for that packet.

Fix:
Added check for dest IP
Converted this check to a function

Signed-off-by: Saravanan K <saravanank@vmware.com>

1 files changed, 27 insertions, 0 deletions

diff --git a/pimd/pim_pim.c b/pimd/pim_pim.c
index 8d7a921cf4..a76fbed203 100644
--- a/pimd/pim_pim.c
+++ b/pimd/pim_pim.c
@@ -137,6 +137,18 @@ void pim_sock_delete(struct interface *ifp, const char *delete_message)
 	sock_close(ifp);
 }
 
+/* For now check dst address for hello, assrt and join/prune is all pim rtr */
+static bool pim_pkt_dst_addr_ok(enum pim_msg_type type, in_addr_t addr)
+{
+	if ((type == PIM_MSG_TYPE_HELLO) || (type == PIM_MSG_TYPE_ASSERT)
+	    || (type == PIM_MSG_TYPE_JOIN_PRUNE)) {
+		if (addr != qpim_all_pim_routers_addr.s_addr)
+			return false;
+	}
+
+	return true;
+}
+
 int pim_pim_packet(struct interface *ifp, uint8_t *buf, size_t len)
 {
 	struct ip *ip_hdr;
@@ -237,6 +249,21 @@ int pim_pim_packet(struct interface *ifp, uint8_t *buf, size_t len)
 		}
 	}
 
+	if (!pim_pkt_dst_addr_ok(header->type, ip_hdr->ip_dst.s_addr)) {
+		char dst_str[INET_ADDRSTRLEN];
+		char src_str[INET_ADDRSTRLEN];
+
+		pim_inet4_dump("<dst?>", ip_hdr->ip_dst, dst_str,
+			       sizeof(dst_str));
+		pim_inet4_dump("<src?>", ip_hdr->ip_src, src_str,
+			       sizeof(src_str));
+		zlog_warn(
+			"%s: Ignoring Pkt. Unexpected IP destination %s for %s (Expected: all_pim_routers_addr) from %s",
+			__func__, dst_str, pim_pim_msgtype2str(header->type),
+			src_str);
+		return -1;
+	}
+
 	switch (header->type) {
 	case PIM_MSG_TYPE_HELLO:
 		return pim_hello_recv(ifp, ip_hdr->ip_src,