[NETFILTER]: nf_conntrack_sip: introduce SIP-URI parsing helper

Introduce a helper function to parse a SIP-URI in a header value, optionally
iterating through all headers of this kind.

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

diff --git a/include/linux/netfilter/nf_conntrack_sip.h b/include/linux/netfilter/nf_conntrack_sip.h
index ccc7014..87bc6f7 100644 (file)
--- a/include/linux/netfilter/nf_conntrack_sip.h
+++ b/include/linux/netfilter/nf_conntrack_sip.h
@@ -67,6 +67,11 @@ extern int ct_sip_get_header(const struct nf_conn *ct, const char *dptr,
                             unsigned int dataoff, unsigned int datalen,
                             enum sip_header_types type,
                             unsigned int *matchoff, unsigned int *matchlen);
+extern int ct_sip_parse_header_uri(const struct nf_conn *ct, const char *dptr,
+                                  unsigned int *dataoff, unsigned int datalen,
+                                  enum sip_header_types type, int *in_header,
+                                  unsigned int *matchoff, unsigned int *matchlen,
+                                  union nf_inet_addr *addr, __be16 *port);
 
 extern int ct_sip_get_sdp_header(const struct nf_conn *ct, const char *dptr,
                                 unsigned int dataoff, unsigned int datalen,

diff --git a/net/netfilter/nf_conntrack_sip.c b/net/netfilter/nf_conntrack_sip.c
index cbc9159..a74d76a 100644 (file)
--- a/net/netfilter/nf_conntrack_sip.c
+++ b/net/netfilter/nf_conntrack_sip.c
@@ -190,6 +190,9 @@ EXPORT_SYMBOL_GPL(ct_sip_parse_request);
  * whitespace and the values. Whitespace in this context means any amount of
  * tabs, spaces and continuation lines, which are treated as a single whitespace
  * character.
+ *
+ * Some headers may appear multiple times. A comma seperated list of values is
+ * equivalent to multiple headers.
  */
 static const struct sip_header ct_sip_hdrs[] = {
        [SIP_HDR_FROM]                  = SIP_HDR("From", "f", "sip:", skp_epaddr_len),
@@ -322,6 +325,110 @@ int ct_sip_get_header(const struct nf_conn *ct, const char *dptr,
 }
 EXPORT_SYMBOL_GPL(ct_sip_get_header);
 
+/* Get next header field in a list of comma seperated values */
+static int ct_sip_next_header(const struct nf_conn *ct, const char *dptr,
+                             unsigned int dataoff, unsigned int datalen,
+                             enum sip_header_types type,
+                             unsigned int *matchoff, unsigned int *matchlen)
+{
+       const struct sip_header *hdr = &ct_sip_hdrs[type];
+       const char *start = dptr, *limit = dptr + datalen;
+       int shift = 0;
+
+       dptr += dataoff;
+
+       dptr = ct_sip_header_search(dptr, limit, ",", strlen(","));
+       if (!dptr)
+               return 0;
+
+       dptr = ct_sip_header_search(dptr, limit, hdr->search, hdr->slen);
+       if (!dptr)
+               return 0;
+       dptr += hdr->slen;
+
+       *matchoff = dptr - start;
+       *matchlen = hdr->match_len(ct, dptr, limit, &shift);
+       if (!*matchlen)
+               return -1;
+       *matchoff += shift;
+       return 1;
+}
+
+/* Walk through headers until a parsable one is found or no header of the
+ * given type is left. */
+static int ct_sip_walk_headers(const struct nf_conn *ct, const char *dptr,
+                              unsigned int dataoff, unsigned int datalen,
+                              enum sip_header_types type, int *in_header,
+                              unsigned int *matchoff, unsigned int *matchlen)
+{
+       int ret;
+
+       if (in_header && *in_header) {
+               while (1) {
+                       ret = ct_sip_next_header(ct, dptr, dataoff, datalen,
+                                                type, matchoff, matchlen);
+                       if (ret > 0)
+                               return ret;
+                       if (ret == 0)
+                               break;
+                       dataoff += *matchoff;
+               }
+               *in_header = 0;
+       }
+
+       while (1) {
+               ret = ct_sip_get_header(ct, dptr, dataoff, datalen,
+                                       type, matchoff, matchlen);
+               if (ret > 0)
+                       break;
+               if (ret == 0)
+                       return ret;
+               dataoff += *matchoff;
+       }
+
+       if (in_header)
+               *in_header = 1;
+       return 1;
+}
+
+/* Locate a SIP header, parse the URI and return the offset and length of
+ * the address as well as the address and port themselves. A stream of
+ * headers can be parsed by handing in a non-NULL datalen and in_header
+ * pointer.
+ */
+int ct_sip_parse_header_uri(const struct nf_conn *ct, const char *dptr,
+                           unsigned int *dataoff, unsigned int datalen,
+                           enum sip_header_types type, int *in_header,
+                           unsigned int *matchoff, unsigned int *matchlen,
+                           union nf_inet_addr *addr, __be16 *port)
+{
+       const char *c, *limit = dptr + datalen;
+       unsigned int p;
+       int ret;
+
+       ret = ct_sip_walk_headers(ct, dptr, dataoff ? *dataoff : 0, datalen,
+                                 type, in_header, matchoff, matchlen);
+       WARN_ON(ret < 0);
+       if (ret == 0)
+               return ret;
+
+       if (!parse_addr(ct, dptr + *matchoff, &c, addr, limit))
+               return -1;
+       if (*c == ':') {
+               c++;
+               p = simple_strtoul(c, (char **)&c, 10);
+               if (p < 1024 || p > 65535)
+                       return -1;
+               *port = htons(p);
+       } else
+               *port = htons(SIP_PORT);
+
+       if (dataoff)
+               *dataoff = c - dptr;
+       return 1;
+}
+EXPORT_SYMBOL_GPL(ct_sip_parse_header_uri);
+
 /* SDP header parsing: a SDP session description contains an ordered set of
  * headers, starting with a section containing general session parameters,
  * optionally followed by multiple media descriptions.