tcp: Unify initial sequence number calculation for IPv4 and IPv6

tcp_seq_init() has separate paths for IPv4 and IPv6 addresses, which means
we will calculate different sequence numbers for IPv4 and equivalent
IPv4-mapped IPv6 addresses.

Change it to treat these the same by always converting the input address
into an inany_addr representation and use that to calculate the sequence
number.

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

2 files changed, 19 insertions, 28 deletions

diff --git a/siphash.c b/siphash.c
index 516a508..811918b 100644
--- a/siphash.c
+++ b/siphash.c
@@ -123,6 +123,7 @@ uint64_t siphash_8b(const uint8_t *in, const uint64_t *k)
  *
  * Return: 32 bits obtained by XORing the two halves of the 64-bit hash output
  */
+/* cppcheck-suppress unusedFunction */
 uint32_t siphash_12b(const uint8_t *in, const uint64_t *k)
 {
 	uint32_t *in32 = (uint32_t *)in;
diff --git a/tcp.c b/tcp.c
index 8ebd90a..ac64b81 100644
--- a/tcp.c
+++ b/tcp.c
@@ -1942,37 +1942,27 @@ static uint32_t tcp_seq_init(const struct ctx *c, int af, const void *addr,
 			     in_port_t dstport, in_port_t srcport,
 			     const struct timespec *now)
 {
+	union inany_addr aany;
+	struct {
+		union inany_addr src;
+		in_port_t srcport;
+		union inany_addr dst;
+		in_port_t dstport;
+	} __attribute__((__packed__)) in = {
+		.srcport = srcport,
+		.dstport = dstport,
+	};
 	uint32_t ns, seq = 0;
 
-	if (af == AF_INET) {
-		struct {
-			struct in_addr src;
-			in_port_t srcport;
-			struct in_addr dst;
-			in_port_t dstport;
-		} __attribute__((__packed__)) in = {
-			.src = *(struct in_addr *)addr,
-			.srcport = srcport,
-			.dst = c->ip4.addr,
-			.dstport = dstport,
-		};
-
-		seq = siphash_12b((uint8_t *)&in, c->tcp.hash_secret);
-	} else if (af == AF_INET6) {
-		struct {
-			struct in6_addr src;
-			in_port_t srcport;
-			struct in6_addr dst;
-			in_port_t dstport;
-		} __attribute__((__packed__)) in = {
-			.src = *(struct in6_addr *)addr,
-			.srcport = srcport,
-			.dst = c->ip6.addr,
-			.dstport = dstport,
-		};
+	inany_from_af(&aany, af, addr);
+	in.src = aany;
+	if (af == AF_INET)
+		inany_from_af(&aany, AF_INET, &c->ip4.addr);
+	else
+		inany_from_af(&aany, AF_INET6, &c->ip6.addr);
+	in.dst = aany;
 
-		seq = siphash_36b((uint8_t *)&in, c->tcp.hash_secret);
-	}
+	seq = siphash_36b((uint8_t *)&in, c->tcp.hash_secret);
 
 	ns = now->tv_sec * 1E9;
 	ns += now->tv_nsec >> 5; /* 32ns ticks, overflows 32 bits every 137s */