[NETFILTER]: nf_conntrack_sip: add seperate SDP header parsing function

SDP and SIP headers are quite different, SIP can have continuation lines,
leading and trailing whitespace after the colon and is mostly case-insensitive
while SDP headers always begin on a new line and are followed by an equal
sign and the value, without any whitespace.

Introduce new SDP header parsing function and convert all users that used
the SIP header parsing function. This will allow to properly deal with the
special SIP cases in the SIP header parsing function later.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 32 insertions, 37 deletions

diff --git a/net/ipv4/netfilter/nf_nat_sip.c b/net/ipv4/netfilter/nf_nat_sip.c
index dd1b2d8..aa8a4f4 100644
--- a/net/ipv4/netfilter/nf_nat_sip.c
+++ b/net/ipv4/netfilter/nf_nat_sip.c
@@ -147,51 +147,46 @@ static unsigned int ip_nat_sip(struct sk_buff *skb,
 	return NF_ACCEPT;
 }
 
-static unsigned int mangle_sip_packet(struct sk_buff *skb,
-				      const char **dptr, unsigned int *datalen,
-				      char *buffer, int bufflen,
-				      enum sip_header_pos pos)
+static int mangle_content_len(struct sk_buff *skb,
+			      const char **dptr, unsigned int *datalen)
 {
 	enum ip_conntrack_info ctinfo;
 	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
-	unsigned int matchlen, matchoff;
+	unsigned int matchoff, matchlen;
+	char buffer[sizeof("65536")];
+	int buflen, c_len;
 
+	/* Get actual SDP length */
+	if (ct_sip_get_sdp_header(ct, *dptr, 0, *datalen,
+				  SDP_HDR_VERSION, SDP_HDR_UNSPEC,
+				  &matchoff, &matchlen) <= 0)
+		return 0;
+	c_len = *datalen - matchoff + strlen("v=");
+
+	/* Now, update SDP length */
 	if (ct_sip_get_info(ct, *dptr, *datalen, &matchoff, &matchlen,
-			    pos) <= 0)
+			    POS_CONTENT) <= 0)
 		return 0;
 
+	buflen = sprintf(buffer, "%u", c_len);
 	return mangle_packet(skb, dptr, datalen, matchoff, matchlen,
-			     buffer, bufflen);
+			     buffer, buflen);
 }
 
-static int mangle_content_len(struct sk_buff *skb,
-			      const char **dptr, unsigned int *datalen)
+static unsigned mangle_sdp_packet(struct sk_buff *skb,
+				  const char **dptr, unsigned int *datalen,
+				  enum sdp_header_types type,
+				  char *buffer, int buflen)
 {
 	enum ip_conntrack_info ctinfo;
 	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
-	unsigned int matchoff, matchlen;
-	char buffer[sizeof("65536")];
-	int bufflen;
+	unsigned int matchlen, matchoff;
 
-	/* Get actual SDP length */
-	if (ct_sip_get_info(ct, *dptr, *datalen, &matchoff,
-			    &matchlen, POS_SDP_HEADER) > 0) {
-
-		/* since ct_sip_get_info() give us a pointer passing 'v='
-		   we need to add 2 bytes in this count. */
-		int c_len = *datalen - matchoff + 2;
-
-		/* Now, update SDP length */
-		if (ct_sip_get_info(ct, *dptr, *datalen, &matchoff,
-				    &matchlen, POS_CONTENT) > 0) {
-
-			bufflen = sprintf(buffer, "%u", c_len);
-			return mangle_packet(skb, dptr, datalen,
-					     matchoff, matchlen,
-					     buffer, bufflen);
-		}
-	}
-	return 0;
+	if (ct_sip_get_sdp_header(ct, *dptr, 0, *datalen, type, SDP_HDR_UNSPEC,
+				  &matchoff, &matchlen) <= 0)
+		return 0;
+	return mangle_packet(skb, dptr, datalen, matchoff, matchlen,
+			     buffer, buflen);
 }
 
 static unsigned int mangle_sdp(struct sk_buff *skb,
@@ -205,18 +200,18 @@ static unsigned int mangle_sdp(struct sk_buff *skb,
 
 	/* Mangle owner and contact info. */
 	bufflen = sprintf(buffer, "%u.%u.%u.%u", NIPQUAD(newip));
-	if (!mangle_sip_packet(skb, dptr, datalen, buffer, bufflen,
-			       POS_OWNER_IP4))
+	if (!mangle_sdp_packet(skb, dptr, datalen, SDP_HDR_OWNER_IP4,
+			       buffer, bufflen))
 		return 0;
 
-	if (!mangle_sip_packet(skb, dptr, datalen, buffer, bufflen,
-			       POS_CONNECTION_IP4))
+	if (!mangle_sdp_packet(skb, dptr, datalen, SDP_HDR_CONNECTION_IP4,
+			       buffer, bufflen))
 		return 0;
 
 	/* Mangle media port. */
 	bufflen = sprintf(buffer, "%u", port);
-	if (!mangle_sip_packet(skb, dptr, datalen, buffer, bufflen,
-			       POS_MEDIA))
+	if (!mangle_sdp_packet(skb, dptr, datalen, SDP_HDR_MEDIA,
+			       buffer, bufflen))
 		return 0;
 
 	return mangle_content_len(skb, dptr, datalen);