netfilter: nf_conntrack_sip: add TCP support

Add TCP support, which is mandated by RFC3261 for all SIP elements.

SIP over TCP is similar to UDP, except that messages are delimited
by Content-Length: headers and multiple messages may appear in one
packet.
Signed-off-by: Patrick McHardy <kaber@trash.net>

include/linux/netfilter/nf_conntrack_sip.h

@@ -84,7 +84,8 @@ enum sip_header_types {
 	SIP_HDR_FROM,
 	SIP_HDR_TO,
 	SIP_HDR_CONTACT,
-	SIP_HDR_VIA,
+	SIP_HDR_VIA_UDP,
+	SIP_HDR_VIA_TCP,
 	SIP_HDR_EXPIRES,
 	SIP_HDR_CONTENT_LENGTH,
 };

net/ipv4/netfilter/nf_nat_sip.c

@@ -122,7 +122,7 @@ static unsigned int ip_nat_sip(struct sk_buff *skb, unsigned int dataoff,
 
 	/* Translate topmost Via header and parameters */
 	if (ct_sip_parse_header_uri(ct, *dptr, NULL, *datalen,
-				    SIP_HDR_VIA, NULL, &matchoff, &matchlen,
+				    SIP_HDR_VIA_UDP, NULL, &matchoff, &matchlen,
 				    &addr, &port) > 0) {
 		unsigned int matchend, poff, plen, buflen, n;
 		char buffer[sizeof("nnn.nnn.nnn.nnn:nnnnn")];