netfilter: nf_conntrack_sip: Add callid parser

Signed-off-by: Simon Horman <[e-mail]>
Acked-by: Julian Anastasov <[e-mail]>

include/linux/netfilter/nf_conntrack_sip.h

···
 	SIP_HDR_VIA_TCP,
 	SIP_HDR_EXPIRES,
 	SIP_HDR_CONTENT_LENGTH,
+	SIP_HDR_CALL_ID,
 };
 
 enum sdp_header_types {

net/netfilter/nf_conntrack_sip.c

···
 	return len;
 }
 
+static int iswordc(const char c)
+{
+	if (isalnum(c) || c == '!' || c == '"' || c == '%' ||
+	    (c >= '(' && c <= '/') || c == ':' || c == '<' || c == '>' ||
+	    c == '?' || (c >= '[' && c <= ']') || c == '_' || c == '`' ||
+	    c == '{' || c == '}' || c == '~')
+		return 1;
+	return 0;
+}
+
+static int word_len(const char *dptr, const char *limit)
+{
+	int len = 0;
+	while (dptr < limit && iswordc(*dptr)) {
+		dptr++;
+		len++;
+	}
+	return len;
+}
+
+static int callid_len(const struct nf_conn *ct, const char *dptr,
+		      const char *limit, int *shift)
+{
+	int len, domain_len;
+
+	len = word_len(dptr, limit);
+	dptr += len;
+	if (!len || dptr == limit || *dptr != '@')
+		return len;
+	dptr++;
+	len++;
+
+	domain_len = word_len(dptr, limit);
+	if (!domain_len)
+		return 0;
+	return len + domain_len;
+}
+
 /* get media type + port length */
 static int media_len(const struct nf_conn *ct, const char *dptr,
 		     const char *limit, int *shift)
···
 	[SIP_HDR_VIA_TCP]		= SIP_HDR("Via", "v", "TCP ", epaddr_len),
 	[SIP_HDR_EXPIRES]		= SIP_HDR("Expires", NULL, NULL, digits_len),
 	[SIP_HDR_CONTENT_LENGTH]	= SIP_HDR("Content-Length", "l", NULL, digits_len),
+	[SIP_HDR_CALL_ID]		= SIP_HDR("Call-Id", "i", NULL, callid_len),
 };
 
 static const char *sip_follow_continuation(const char *dptr, const char *limit)