[patch v5 02/12] netfilter: nf_conntrack_sip: Add callid parser

[Simon Horman <horms@xxxxxxxxxxxx>]

Signed-off-by: Simon Horman <horms@xxxxxxxxxxxx>
Acked-by: Julian Anastasov <ja@xxxxxx>

--- 

The motivation for this is for it to be used by LVS as per
subsequent patches.

* Patrick McHardy suggested changing word_len to check for the
  next newline or whitespace. But I believe this is incorrect.
  For example '#' would be permitted but it is invalid
  in a word according to RFC3261.


diff --git a/include/linux/netfilter/nf_conntrack_sip.h 
b/include/linux/netfilter/nf_conntrack_sip.h
index ff8cfbc..0ce91d5 100644
--- a/include/linux/netfilter/nf_conntrack_sip.h
+++ b/include/linux/netfilter/nf_conntrack_sip.h
@@ -89,6 +89,7 @@ enum sip_header_types {
        SIP_HDR_VIA_TCP,
        SIP_HDR_EXPIRES,
        SIP_HDR_CONTENT_LENGTH,
+       SIP_HDR_CALL_ID,
 };
 
 enum sdp_header_types {
diff --git a/net/netfilter/nf_conntrack_sip.c b/net/netfilter/nf_conntrack_sip.c
index 2fd1ea2..715ce54 100644
--- a/net/netfilter/nf_conntrack_sip.c
+++ b/net/netfilter/nf_conntrack_sip.c
@@ -130,6 +130,44 @@ static int digits_len(const struct nf_conn *ct, const char 
*dptr,
        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)
@@ -299,6 +337,7 @@ static const struct sip_header ct_sip_hdrs[] = {
        [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)
-- 
1.7.1


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