ip: Use iov_tail in ipv6_l4hdr()

Use packet_data() and extract headers using IOV_REMOVE_HEADER()
and IOV_PEEK_HEADER() rather than packet_get().

Signed-off-by: Laurent Vivier <lvivier@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

4 files changed, 20 insertions, 21 deletions

diff --git a/ip.c b/ip.c
index 2cc7f65..9a7f4c5 100644
--- a/ip.c
+++ b/ip.c
@@ -23,50 +23,47 @@
 
 /**
  * ipv6_l4hdr() - Find pointer to L4 header in IPv6 packet and extract protocol
- * @p:		Packet pool, packet number @idx has IPv6 header at @offset
- * @idx:	Index of packet in pool
- * @offset:	Pre-calculated IPv6 header offset
+ * @data:	IPv6 packet
  * @proto:	Filled with L4 protocol number
  * @dlen:	Data length (payload excluding header extensions), set on return
  *
- * Return: pointer to L4 header, NULL if not found
+ * Return: true if the L4 header is found and @data, @proto, @dlen are set,
+ * 	   false on error. Outputs are indeterminate on failure.
  */
-char *ipv6_l4hdr(const struct pool *p, int idx, size_t offset, uint8_t *proto,
-		 size_t *dlen)
+bool ipv6_l4hdr(struct iov_tail *data, uint8_t *proto, size_t *dlen)
 {
+	struct ipv6_opt_hdr o_storage;
 	const struct ipv6_opt_hdr *o;
+	struct ipv6hdr ip6h_storage;
 	const struct ipv6hdr *ip6h;
-	char *base;
 	int hdrlen;
 	uint8_t nh;
 
-	base = packet_get(p, idx, 0, 0, NULL);
-	ip6h = packet_get(p, idx, offset, sizeof(*ip6h), dlen);
+	ip6h = IOV_REMOVE_HEADER(data, ip6h_storage);
 	if (!ip6h)
-		return NULL;
-
-	offset += sizeof(*ip6h);
+		return false;
 
 	nh = ip6h->nexthdr;
 	if (!IPV6_NH_OPT(nh))
 		goto found;
 
-	while ((o = packet_get_try(p, idx, offset, sizeof(*o), dlen))) {
+	while ((o = IOV_PEEK_HEADER(data, o_storage))) {
 		nh = o->nexthdr;
 		hdrlen = (o->hdrlen + 1) * 8;
 
 		if (IPV6_NH_OPT(nh))
-			offset += hdrlen;
+			iov_drop_header(data, hdrlen);
 		else
 			goto found;
 	}
 
-	return NULL;
+	return false;
 
 found:
-	if (nh == 59)
-		return NULL;
+	if (nh == IPPROTO_NONE)
+		return false;
 
+	*dlen = iov_tail_size(data);
 	*proto = nh;
-	return base + offset;
+	return true;
 }
diff --git a/ip.h b/ip.h
index 24509d9..5830b92 100644
--- a/ip.h
+++ b/ip.h
@@ -115,8 +115,7 @@ static inline uint32_t ip6_get_flow_lbl(const struct ipv6hdr *ip6h)
 		ip6h->flow_lbl[2];
 }
 
-char *ipv6_l4hdr(const struct pool *p, int idx, size_t offset, uint8_t *proto,
-		 size_t *dlen);
+bool ipv6_l4hdr(struct iov_tail *data, uint8_t *proto, size_t *dlen);
 
 /* IPv6 link-local all-nodes multicast address, ff02::1 */
 static const struct in6_addr in6addr_ll_all_nodes = {
diff --git a/packet.c b/packet.c
index 34b1722..014b353 100644
--- a/packet.c
+++ b/packet.c
@@ -133,6 +133,7 @@ void packet_add_do(struct pool *p, struct iov_tail *data,
  *
  * Return: pointer to start of data range, NULL on invalid range or descriptor
  */
+/* cppcheck-suppress [staticFunction] */
 void *packet_get_try_do(const struct pool *p, size_t idx, size_t offset,
 			size_t len, size_t *left, const char *func, int line)
 {
diff --git a/tap.c b/tap.c
index 7cb7494..497440a 100644
--- a/tap.c
+++ b/tap.c
@@ -911,8 +911,10 @@ resume:
 		if (plen != check)
 			continue;
 
-		if (!(l4h = ipv6_l4hdr(in, i, sizeof(*eh), &proto, &l4len)))
+		data = IOV_TAIL_FROM_BUF(ip6h, sizeof(*ip6h) + check, 0);
+		if (!ipv6_l4hdr(&data, &proto, &l4len))
 			continue;
+		l4h = (char *)data.iov[0].iov_base + data.off;
 
 		if (IN6_IS_ADDR_LOOPBACK(saddr) || IN6_IS_ADDR_LOOPBACK(daddr)) {
 			char sstr[INET6_ADDRSTRLEN], dstr[INET6_ADDRSTRLEN];