[PATCH v2 08/10] tcp: Re-use flowside_hash for initial sequence number generation

[David Gibson <david@gibson.dropbear.id.au>]

We generate TCP initial sequence numbers, when we need them, from a hash
of the source and destination addresses and ports, plus a timestamp.
The contents of that hash are now exactly the same as the flowside_hash()
we use elsewhere.  The values won't be identical because we order the
fields in the hash differently, but that doesn't matter for our purposes.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 tcp.c | 15 +--------------
 1 file changed, 1 insertion(+), 14 deletions(-)

diff --git a/tcp.c b/tcp.c
index 27cdd15..a9ddce6 100644
--- a/tcp.c
+++ b/tcp.c
@@ -1754,20 +1754,7 @@ static void tcp_clamp_window(const struct ctx *c, struct tcp_tap_conn *conn,
 static void tcp_seq_init(const struct ctx *c, struct tcp_tap_conn *conn,
 			 const struct timespec *now)
 {
-	struct {
-		union inany_addr src;
-		in_port_t srcport;
-		union inany_addr dst;
-		in_port_t dstport;
-	} __attribute__((__packed__)) in = {
-		.src = TAPSIDE(conn)->faddr,
-		.srcport = TAPSIDE(conn)->fport,
-		.dst = TAPSIDE(conn)->eaddr,
-		.dstport = TAPSIDE(conn)->eport,
-	};
-	uint32_t ns, seq = 0;
-
-	seq = siphash_36b((uint8_t *)&in, c->tcp.hash_secret);
+	uint32_t ns, seq = flowside_hash(TAPSIDE(conn), c->tcp.hash_secret);
 
 	/* 32ns ticks, overflows 32 bits every 137s */
 	ns = (now->tv_sec * 1000000000 + now->tv_nsec) >> 5;
-- 
@@ -1754,20 +1754,7 @@ static void tcp_clamp_window(const struct ctx *c, struct tcp_tap_conn *conn,
 static void tcp_seq_init(const struct ctx *c, struct tcp_tap_conn *conn,
 			 const struct timespec *now)
 {
-	struct {
-		union inany_addr src;
-		in_port_t srcport;
-		union inany_addr dst;
-		in_port_t dstport;
-	} __attribute__((__packed__)) in = {
-		.src = TAPSIDE(conn)->faddr,
-		.srcport = TAPSIDE(conn)->fport,
-		.dst = TAPSIDE(conn)->eaddr,
-		.dstport = TAPSIDE(conn)->eport,
-	};
-	uint32_t ns, seq = 0;
-
-	seq = siphash_36b((uint8_t *)&in, c->tcp.hash_secret);
+	uint32_t ns, seq = flowside_hash(TAPSIDE(conn), c->tcp.hash_secret);
 
 	/* 32ns ticks, overflows 32 bits every 137s */
 	ns = (now->tv_sec * 1000000000 + now->tv_nsec) >> 5;
-- 
2.41.0