[PATCH 09/10] tcp: Have tcp_seq_init() take its parameters from struct tcp_conn

tcp_seq_init() takes a number of parameters for the connection, but at
every call site, these are already populated in the tcp_conn structure.
Likewise we always store the result into the @seq_to_tap field.

Use this to simplify tcp_seq_init().

Signed-off-by: David Gibson <david(a)gibson.dropbear.id.au>
---
 tcp.c | 43 +++++++++++++------------------------------
 1 file changed, 13 insertions(+), 30 deletions(-)

diff --git a/tcp.c b/tcp.c
index b9d0510..59e03ff 100644
--- a/tcp.c
+++ b/tcp.c
@@ -1999,17 +1999,11 @@ static void tcp_clamp_window(const struct ctx *c, struct tcp_conn
*conn,
 /**
  * tcp_seq_init() - Calculate initial sequence number according to RFC 6528
  * @c:		Execution context
- * @af:		Address family, AF_INET or AF_INET6
- * @addr:	Remote address, pointer to in_addr or in6_addr
- * @dstport:	Destination port, connection-wise, network order
- * @srcport:	Source port, connection-wise, network order
+ * @conn:	TCP connection, with addr, sock_port and tap_port populated
  * @now:	Current timestamp
- *
- * Return: initial TCP sequence
  */
-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)
+static void tcp_seq_init(const struct ctx *c, struct tcp_conn *conn,
+			 const struct timespec *now)
 {
 	struct {
 		struct in6_addr src;
@@ -2017,19 +2011,17 @@ static uint32_t tcp_seq_init(const struct ctx *c, int af, const
void *addr,
 		struct in6_addr dst;
 		in_port_t dstport;
 	} __attribute__((__packed__)) in = {
-		.srcport = srcport,
-		.dstport = dstport,
+		.src = conn->addr,
+		.srcport = conn->tap_port,
+		.dstport = conn->sock_port,
 	};
 	uint32_t ns, seq = 0;
 
-	if (af == AF_INET) {
-		struct in6_addr tmp;
-		encode_ip4mapped_ip6(&tmp, addr);
-		in.src = tmp;
-		encode_ip4mapped_ip6(&tmp, &c->ip4.addr);
-		in.dst = tmp;
+	if (CONN_V4(conn)) {
+		struct in6_addr v4mapped;
+		encode_ip4mapped_ip6(&v4mapped, &c->ip4.addr);
+		in.dst = v4mapped;
 	} else {
-		in.src = *(struct in6_addr *)addr;
 		in.dst = c->ip6.addr;
 	}
 
@@ -2038,7 +2030,7 @@ static uint32_t tcp_seq_init(const struct ctx *c, int af, const void
*addr,
 	ns = now->tv_sec * 1E9;
 	ns += now->tv_nsec >> 5; /* 32ns ticks, overflows 32 bits every 137s */
 
-	return seq + ns;
+	conn->seq_to_tap = seq + ns;
 }
 
 /**
@@ -2199,7 +2191,7 @@ static void tcp_conn_from_tap(struct ctx *c, int af, const void
*addr,
 	conn->seq_from_tap = conn->seq_init_from_tap + 1;
 	conn->seq_ack_to_tap = conn->seq_from_tap;
 
-	conn->seq_to_tap = tcp_seq_init(c, af, addr, th->dest, th->source, now);
+	tcp_seq_init(c, conn, now);
 	conn->seq_ack_from_tap = conn->seq_to_tap + 1;
 
 	tcp_hash_insert(c, conn);
@@ -2855,11 +2847,6 @@ static void tcp_conn_from_sock(struct ctx *c, union epoll_ref ref,
 
 		conn->sock_port = ntohs(sa6.sin6_port);
 		conn->tap_port = ref.r.p.tcp.tcp.index;
-
-		conn->seq_to_tap = tcp_seq_init(c, AF_INET6, &sa6.sin6_addr,
-						conn->sock_port,
-						conn->tap_port,
-						now);
 	} else {
 		struct sockaddr_in sa4;
 
@@ -2874,13 +2861,9 @@ static void tcp_conn_from_sock(struct ctx *c, union epoll_ref ref,
 
 		conn->sock_port = ntohs(sa4.sin_port);
 		conn->tap_port = ref.r.p.tcp.tcp.index;
-
-		conn->seq_to_tap = tcp_seq_init(c, AF_INET, &sa4.sin_addr,
-						conn->sock_port,
-						conn->tap_port,
-						now);
 	}
 
+	tcp_seq_init(c, conn, now);
 	tcp_hash_insert(c, conn);
 
 	conn->seq_ack_from_tap = conn->seq_to_tap + 1;
-- 
2.38.1