netfilter -stable: nf_nat_sip: c= is optional for session

[Patrick McHardy <kaber@xxxxxxxxx>]

This patch fixes a regression in 2.6.26 in the SIP conntrack
helper.

Please apply, thanks.

commit 3ce2313ead6e9d2e2f25be32d80c3930b894cf61
Author: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Date:   Wed Jul 30 15:40:36 2008 +0200

    netfilter: nf_nat_sip: c= is optional for session
    
    Upstream commit c71529e4:
    
    According to RFC2327, the connection information is optional
    in the session description since it can be specified in the
    media description instead.
    
    My provider does exactly that and does not provide any connection
    information in the session description.  As a result the new
    kernel drops all invite responses.
    
    This patch makes it optional as documented.
    
    Signed-off-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
    Signed-off-by: Patrick McHardy <kaber@xxxxxxxxx>
    Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>

diff --git a/net/ipv4/netfilter/nf_nat_sip.c b/net/ipv4/netfilter/nf_nat_sip.c
index 4334d5c..1454432 100644
--- a/net/ipv4/netfilter/nf_nat_sip.c
+++ b/net/ipv4/netfilter/nf_nat_sip.c
@@ -318,11 +318,11 @@ static int mangle_content_len(struct sk_buff *skb,
 			     buffer, buflen);
 }
 
-static unsigned mangle_sdp_packet(struct sk_buff *skb, const char **dptr,
-				  unsigned int dataoff, unsigned int *datalen,
-				  enum sdp_header_types type,
-				  enum sdp_header_types term,
-				  char *buffer, int buflen)
+static int mangle_sdp_packet(struct sk_buff *skb, const char **dptr,
+			     unsigned int dataoff, unsigned int *datalen,
+			     enum sdp_header_types type,
+			     enum sdp_header_types term,
+			     char *buffer, int buflen)
 {
 	enum ip_conntrack_info ctinfo;
 	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
@@ -330,9 +330,9 @@ static unsigned mangle_sdp_packet(struct sk_buff *skb, const char **dptr,
 
 	if (ct_sip_get_sdp_header(ct, *dptr, dataoff, *datalen, type, term,
 				  &matchoff, &matchlen) <= 0)
-		return 0;
+		return -ENOENT;
 	return mangle_packet(skb, dptr, datalen, matchoff, matchlen,
-			     buffer, buflen);
+			     buffer, buflen) ? 0 : -EINVAL;
 }
 
 static unsigned int ip_nat_sdp_addr(struct sk_buff *skb, const char **dptr,
@@ -346,8 +346,8 @@ static unsigned int ip_nat_sdp_addr(struct sk_buff *skb, const char **dptr,
 	unsigned int buflen;
 
 	buflen = sprintf(buffer, NIPQUAD_FMT, NIPQUAD(addr->ip));
-	if (!mangle_sdp_packet(skb, dptr, dataoff, datalen, type, term,
-			       buffer, buflen))
+	if (mangle_sdp_packet(skb, dptr, dataoff, datalen, type, term,
+			      buffer, buflen))
 		return 0;
 
 	return mangle_content_len(skb, dptr, datalen);
@@ -381,15 +381,27 @@ static unsigned int ip_nat_sdp_session(struct sk_buff *skb, const char **dptr,
 
 	/* Mangle session description owner and contact addresses */
 	buflen = sprintf(buffer, "%u.%u.%u.%u", NIPQUAD(addr->ip));
-	if (!mangle_sdp_packet(skb, dptr, dataoff, datalen,
+	if (mangle_sdp_packet(skb, dptr, dataoff, datalen,
 			       SDP_HDR_OWNER_IP4, SDP_HDR_MEDIA,
 			       buffer, buflen))
 		return 0;
 
-	if (!mangle_sdp_packet(skb, dptr, dataoff, datalen,
-			       SDP_HDR_CONNECTION_IP4, SDP_HDR_MEDIA,
-			       buffer, buflen))
+	switch (mangle_sdp_packet(skb, dptr, dataoff, datalen,
+				  SDP_HDR_CONNECTION_IP4, SDP_HDR_MEDIA,
+				  buffer, buflen)) {
+	case 0:
+	/*
+	 * RFC 2327:
+	 *
+	 * Session description
+	 *
+	 * c=* (connection information - not required if included in all media)
+	 */
+	case -ENOENT:
+		break;
+	default:
 		return 0;
+	}
 
 	return mangle_content_len(skb, dptr, datalen);
 }