mptcp: add port support for ADD_ADDR suboption writing

In rfc8684, the length of ADD_ADDR suboption with IPv4 address and port
is 18 octets, but mptcp_write_options is 32-bit aligned, so we need to
pad it to 20 octets. All the other port related option lengths need to
be added up 2 octets similarly.

This patch added a new field 'port' in mptcp_out_options. When this
field is set with a port number, we need to add up 4 octets for the
ADD_ADDR suboption, and put the port number into the suboption.
Signed-off-by: Geliang Tang <geliangtang@gmail.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/mptcp.h

@@ -46,6 +46,7 @@ struct mptcp_out_options {
 #endif
 	};
 	u8 addr_id;
+	u16 port;
 	u64 ahmac;
 	u8 rm_id;
 	u8 join_id;

net/mptcp/options.c

@@ -1083,6 +1083,9 @@ void mptcp_write_options(__be32 *ptr, const struct tcp_sock *tp,
 			len = TCPOLEN_MPTCP_ADD_ADDR6_BASE;
 #endif
 
+		if (opts->port)
+			len += TCPOLEN_MPTCP_PORT_LEN;
+
 		if (opts->ahmac) {
 			len += sizeof(opts->ahmac);
 			echo = 0;
@@ -1100,10 +1103,31 @@ void mptcp_write_options(__be32 *ptr, const struct tcp_sock *tp,
 			ptr += 4;
 		}
 #endif
+
+		if (!opts->port) {
 			if (opts->ahmac) {
 				put_unaligned_be64(opts->ahmac, ptr);
 				ptr += 2;
 			}
+		} else {
+			if (opts->ahmac) {
+				u8 *bptr = (u8 *)ptr;
+
+				put_unaligned_be16(opts->port, bptr);
+				bptr += 2;
+				put_unaligned_be64(opts->ahmac, bptr);
+				bptr += 8;
+				put_unaligned_be16(TCPOPT_NOP << 8 |
+						   TCPOPT_NOP, bptr);
+
+				ptr += 3;
+			} else {
+				put_unaligned_be32(opts->port << 16 |
+						   TCPOPT_NOP << 8 |
+						   TCPOPT_NOP, ptr);
+				ptr += 1;
+			}
+		}
 	}
 
 	if (OPTION_MPTCP_RM_ADDR & opts->suboptions) {

net/mptcp/protocol.h

@@ -49,14 +49,14 @@
 #define TCPOLEN_MPTCP_DSS_MAP64		14
 #define TCPOLEN_MPTCP_DSS_CHECKSUM	2
 #define TCPOLEN_MPTCP_ADD_ADDR		16
-#define TCPOLEN_MPTCP_ADD_ADDR_PORT	18
+#define TCPOLEN_MPTCP_ADD_ADDR_PORT	20
 #define TCPOLEN_MPTCP_ADD_ADDR_BASE	8
-#define TCPOLEN_MPTCP_ADD_ADDR_BASE_PORT	10
+#define TCPOLEN_MPTCP_ADD_ADDR_BASE_PORT	12
 #define TCPOLEN_MPTCP_ADD_ADDR6		28
-#define TCPOLEN_MPTCP_ADD_ADDR6_PORT	30
+#define TCPOLEN_MPTCP_ADD_ADDR6_PORT	32
 #define TCPOLEN_MPTCP_ADD_ADDR6_BASE	20
-#define TCPOLEN_MPTCP_ADD_ADDR6_BASE_PORT	22
-#define TCPOLEN_MPTCP_PORT_LEN		2
+#define TCPOLEN_MPTCP_ADD_ADDR6_BASE_PORT	24
+#define TCPOLEN_MPTCP_PORT_LEN		4
 #define TCPOLEN_MPTCP_RM_ADDR_BASE	4
 
 /* MPTCP MP_JOIN flags */