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Commit 05e3ced2 authored by Patrick McHardy's avatar Patrick McHardy Committed by David S. Miller
Browse files

[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: default avatarPatrick McHardy <kaber@trash.net>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent ea45f12a

include/linux/netfilter/nf_conntrack_sip.h

+5 −0
Original line number Diff line number Diff line
@@ -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,

net/netfilter/nf_conntrack_sip.c

+107 −0
Original line number Diff line number Diff line
@@ -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.