vrrpd: fix packet encode

* Properly encode VRRP packets
* Calculate checksum appropriately
* Update signature to provide caller both packet and result length

Signed-off-by: Quentin Young <qlyoung@cumulusnetworks.com>

1 files changed, 39 insertions, 23 deletions

diff --git a/vrrpd/vrrp_packet.c b/vrrpd/vrrp_packet.c
index a5eb40fda8..608be06a0c 100644
--- a/vrrpd/vrrp_packet.c
+++ b/vrrpd/vrrp_packet.c
@@ -19,32 +19,48 @@
  */
 #include <zebra.h>
 
-#include "memory.h"
-#include "ipaddr.h"
+#include "lib/memory.h"
+#include "lib/ipaddr.h"
+#include "lib/checksum.h"
 
 #include "vrrp_packet.h"
 
-/*
- * Builds a VRRP packet.
- */
-struct vrrp_pkt *vrrp_pkt_build(uint8_t vrid, uint8_t prio,
-				uint16_t max_adver_int, bool v6, uint8_t numip,
-				void **ips)
+ssize_t vrrp_pkt_build(struct vrrp_pkt **pkt, uint8_t vrid, uint8_t prio,
+		       uint16_t max_adver_int, bool v6, uint8_t numip,
+		       void **ips)
 {
+	/* Used for pointer math when filling IPvX field */
+	struct in6_addr *v6ptr;
+	struct in_addr *v4ptr;
+
 	size_t addrsz = v6 ? sizeof(struct in6_addr) : sizeof(struct in_addr);
-	struct vrrp_pkt *pkt =
-		XCALLOC(MTYPE_TMP, sizeof(struct vrrp_pkt) + addrsz * numip);
-
-	pkt->hdr.version = VRRP_VERSION;
-	pkt->hdr.type = VRRP_TYPE_ADVERTISEMENT;
-	pkt->hdr.vrid = vrid;
-	pkt->hdr.priority = prio;
-	pkt->hdr.v3.rsvd = 0;
-	pkt->hdr.v3.adver_int = max_adver_int;
-	for (uint8_t i = 0; i < numip; i++)
-		memcpy(&pkt->addrs[i].v4, ips[i], addrsz);
-	/* FIXME */
-	pkt->hdr.chksum = 0;
-
-	return pkt;
+	size_t pktsize = sizeof(struct vrrp_hdr) + addrsz * numip;
+	*pkt = XCALLOC(MTYPE_TMP, pktsize);
+
+	v6ptr = (struct in6_addr *) (*pkt)->addrs;
+	v4ptr = (struct in_addr *) (*pkt)->addrs;
+
+	(*pkt)->hdr.vertype |= VRRP_VERSION << 4;
+	(*pkt)->hdr.vertype |= VRRP_TYPE_ADVERTISEMENT;
+	(*pkt)->hdr.vrid = vrid;
+	(*pkt)->hdr.priority = prio;
+	(*pkt)->hdr.naddr = numip;
+	(*pkt)->hdr.v3.adver_int = htons(max_adver_int);
+
+	char buf[INET_ADDRSTRLEN];
+	for (int i = 0; i < numip; i++) {
+		/* If v4, treat as array of v4 addresses */
+		inet_ntop(AF_INET, ips[i], buf, sizeof(buf));
+		if (!v6)
+			memcpy(&v4ptr[i], ips[i], addrsz);
+		else
+			memcpy(&v6ptr[i], ips[i], addrsz);
+		inet_ntop(AF_INET, &v4ptr[i], buf, sizeof(buf));
+	}
+	(*pkt)->hdr.chksum = 0;
+
+	uint16_t chksum = in_cksum(*pkt, pktsize);
+	(*pkt)->hdr.chksum = htons(chksum);
+
+	return pktsize;
 }