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[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>
This commit is contained in:
Patrick McHardy 2008-03-25 20:19:13 -07:00 committed by David S. Miller
parent ea45f12a27
commit 05e3ced297
2 changed files with 112 additions and 0 deletions
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5
include/linux/netfilter/nf_conntrack_sip.h
View File

@ -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,

107
net/netfilter/nf_conntrack_sip.c
View File

@ -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.