eigrpd: Rework ack sent to neighbor

EIGRP schedules and builds packets to send in the future.
Before those packets are being sent, we are receiving
update information from our peer.  At that time we
need to reach into the built packet and reset the
outgoing ack to a better value.

Signed-off-by: Donald Sharp <sharpd@cumulusnetworks.com>

1 files changed, 32 insertions, 31 deletions

diff --git a/eigrpd/eigrp_packet.c b/eigrpd/eigrp_packet.c
index 84c1b1c59..9f3de1014 100644
--- a/eigrpd/eigrp_packet.c
+++ b/eigrpd/eigrp_packet.c
@@ -299,18 +299,6 @@ int eigrp_check_sha256_digest(struct stream *s,
 	return 1;
 }
 
-/*
- * eigrp_packet_dump
- *
- * This routing dumps the contents of the IP packet either received or
- * built by EIGRP.
- */
-static void eigrp_packet_dump(struct stream *s)
-{
-	// not yet...
-	return;
-}
-
 int eigrp_write(struct thread *thread)
 {
 	struct eigrp *eigrp = THREAD_ARG(thread);
@@ -322,6 +310,7 @@ int eigrp_write(struct thread *thread)
 	struct msghdr msg;
 	struct iovec iov[2];
 	u_int16_t opcode = 0;
+	u_int32_t seqno, ack;
 
 	int ret;
 	int flags = 0;
@@ -357,6 +346,25 @@ int eigrp_write(struct thread *thread)
 	memset(&iph, 0, sizeof(struct ip));
 	memset(&sa_dst, 0, sizeof(sa_dst));
 
+	/*
+	 * We build and schedule packets to go out
+	 * in the future.  In the mean time we may
+	 * process some update packets from the
+	 * neighbor, thus making it necessary
+	 * to update the ack we are using for
+	 * this outgoing packet.
+	 */
+	eigrph = (struct eigrp_header *)STREAM_DATA(ep->s);
+	opcode = eigrph->opcode;
+	seqno = ntohl(eigrph->sequence);
+	ack = ntohl(eigrph->ack);
+	if (ep->nbr && (ack != ep->nbr->recv_sequence_number)) {
+		eigrph->ack = htonl(ep->nbr->recv_sequence_number);
+		ack = ep->nbr->recv_sequence_number;
+		eigrph->checksum = 0;
+		eigrp_packet_checksum(ei, ep->s, ep->length);
+	}
+
 	sa_dst.sin_family = AF_INET;
 #ifdef HAVE_STRUCT_SOCKADDR_IN_SIN_LEN
 	sa_dst.sin_len = sizeof(sa_dst);
@@ -412,8 +420,9 @@ int eigrp_write(struct thread *thread)
 	if (IS_DEBUG_EIGRP_TRANSMIT(0, SEND)) {
 		eigrph = (struct eigrp_header *)STREAM_DATA(ep->s);
 		opcode = eigrph->opcode;
-		zlog_debug("Sending [%s] to [%s] via [%s] ret [%d].",
+		zlog_debug("Sending [%s][%d/%d] to [%s] via [%s] ret [%d].",
 			   lookup_msg(eigrp_packet_type_str, opcode, NULL),
+			   seqno, ack,
 			   inet_ntoa(ep->dst), IF_NAME(ei), ret);
 	}
 
@@ -425,18 +434,6 @@ int eigrp_write(struct thread *thread)
 			iph.ip_len, ei->ifp->name, ei->ifp->mtu,
 			safe_strerror(errno));
 
-	/* Show debug sending packet. */
-	if (IS_DEBUG_EIGRP_TRANSMIT(0, SEND)
-	    && (IS_DEBUG_EIGRP_TRANSMIT(0, PACKET_DETAIL))) {
-		zlog_debug(
-			"-----------------------------------------------------");
-		eigrp_ip_header_dump(&iph);
-		stream_set_getp(ep->s, 0);
-		eigrp_packet_dump(ep->s);
-		zlog_debug(
-			"-----------------------------------------------------");
-	}
-
 	/* Now delete packet from queue. */
 	eigrp_packet_delete(ei);
 
@@ -615,12 +612,16 @@ int eigrp_read(struct thread *thread)
 	   start of the eigrp TLVs */
 	opcode = eigrph->opcode;
 
-	if (IS_DEBUG_EIGRP_TRANSMIT(0, RECV))
-		zlog_debug(
-			"Received [%s] length [%u] via [%s] src [%s] dst [%s]",
-			lookup_msg(eigrp_packet_type_str, opcode, NULL), length,
-			IF_NAME(ei), inet_ntoa(iph->ip_src),
-			inet_ntoa(iph->ip_dst));
+	if (IS_DEBUG_EIGRP_TRANSMIT(0, RECV)) {
+		char src[100], dst[100];
+
+		strcpy(src, inet_ntoa(iph->ip_src));
+		strcpy(dst, inet_ntoa(iph->ip_dst));
+		zlog_debug("Received [%s][%d/%d] length [%u] via [%s] src [%s] dst [%s]",
+			   lookup_msg(eigrp_packet_type_str, opcode, NULL),
+			   ntohl(eigrph->sequence), ntohl(eigrph->ack), length,
+			   IF_NAME(ei), src, dst);
+	}
 
 	/* Read rest of the packet and call each sort of packet routine. */
 	stream_forward_getp(ibuf, EIGRP_HEADER_LEN);