[PATCH 03/10] tcp: Partially unify IPv4 and IPv6 paths in tcp_hash_match()

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

When given an IPv4 address tcp_hash_match() checks if the connection
stores an IPv4-mapped IPv6 address, and if so compares the mapped part of
that address to the given address.  This is equivalent to converting a
given IPv4 address to an IPv4-mapped IPv6 address then comparing it to the
connection address using the existing IPv6 logic.

Convert to this slightly simpler form, which will also allow some further
simplifications in future.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 tcp.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/tcp.c b/tcp.c
index 26dd268..508d6e9 100644
--- a/tcp.c
+++ b/tcp.c
@@ -1285,13 +1285,14 @@ static int tcp_opt_get(const char *opts, size_t len, uint8_t type_find,
 static int tcp_hash_match(const struct tcp_conn *conn, int af, const void *addr,
 			  in_port_t tap_port, in_port_t sock_port)
 {
-	if (af == AF_INET && CONN_V4(conn)			&&
-	    !memcmp(&conn->a.a4.a, addr, sizeof(conn->a.a4.a))	&&
-	    conn->tap_port == tap_port && conn->sock_port == sock_port)
-		return 1;
+	struct in6_addr v4mapped;
+
+	if (af == AF_INET) {
+		encode_ip4mapped_ip6(&v4mapped, addr);
+		addr = &v4mapped;
+	}
 
-	if (af == AF_INET6					&&
-	    IN6_ARE_ADDR_EQUAL(&conn->a.a6, addr)		&&
+	if (IN6_ARE_ADDR_EQUAL(&conn->a.a6, addr)		&&
 	    conn->tap_port == tap_port && conn->sock_port == sock_port)
 		return 1;
 
-- 
@@ -1285,13 +1285,14 @@ static int tcp_opt_get(const char *opts, size_t len, uint8_t type_find,
 static int tcp_hash_match(const struct tcp_conn *conn, int af, const void *addr,
 			  in_port_t tap_port, in_port_t sock_port)
 {
-	if (af == AF_INET && CONN_V4(conn)			&&
-	    !memcmp(&conn->a.a4.a, addr, sizeof(conn->a.a4.a))	&&
-	    conn->tap_port == tap_port && conn->sock_port == sock_port)
-		return 1;
+	struct in6_addr v4mapped;
+
+	if (af == AF_INET) {
+		encode_ip4mapped_ip6(&v4mapped, addr);
+		addr = &v4mapped;
+	}
 
-	if (af == AF_INET6					&&
-	    IN6_ARE_ADDR_EQUAL(&conn->a.a6, addr)		&&
+	if (IN6_ARE_ADDR_EQUAL(&conn->a.a6, addr)		&&
 	    conn->tap_port == tap_port && conn->sock_port == sock_port)
 		return 1;
 
-- 
2.38.1