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[NETFILTER]: nf_conntrack_sip: support method specific request/respon…
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…se handling

Add support for per-method request/response handlers and perform SDP
parsing for INVITE/UPDATE requests and for all informational and
successful responses.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Patrick McHardy authored and David S. Miller committed Mar 26, 2008
1 parent 7d3dd04 commit 30f33e6
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Showing 2 changed files with 117 additions and 10 deletions.
20 changes: 20 additions & 0 deletions include/linux/netfilter/nf_conntrack_sip.h
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Original file line number Diff line number Diff line change
Expand Up @@ -5,6 +5,25 @@
#define SIP_PORT 5060
#define SIP_TIMEOUT 3600

struct sip_handler {
const char *method;
unsigned int len;
int (*request)(struct sk_buff *skb,
const char **dptr, unsigned int *datalen,
unsigned int cseq);
int (*response)(struct sk_buff *skb,
const char **dptr, unsigned int *datalen,
unsigned int cseq, unsigned int code);
};

#define SIP_HANDLER(__method, __request, __response) \
{ \
.method = (__method), \
.len = sizeof(__method) - 1, \
.request = (__request), \
.response = (__response), \
}

struct sip_header {
const char *name;
const char *cname;
Expand Down Expand Up @@ -35,6 +54,7 @@ struct sip_header {
__SIP_HDR(__name, NULL, __search, __match)

enum sip_header_types {
SIP_HDR_CSEQ,
SIP_HDR_FROM,
SIP_HDR_TO,
SIP_HDR_CONTACT,
Expand Down
107 changes: 97 additions & 10 deletions net/netfilter/nf_conntrack_sip.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -212,6 +212,7 @@ EXPORT_SYMBOL_GPL(ct_sip_parse_request);
* equivalent to multiple headers.
*/
static const struct sip_header ct_sip_hdrs[] = {
[SIP_HDR_CSEQ] = SIP_HDR("CSeq", NULL, NULL, digits_len),
[SIP_HDR_FROM] = SIP_HDR("From", "f", "sip:", skp_epaddr_len),
[SIP_HDR_TO] = SIP_HDR("To", "t", "sip:", skp_epaddr_len),
[SIP_HDR_CONTACT] = SIP_HDR("Contact", "m", "sip:", skp_epaddr_len),
Expand Down Expand Up @@ -566,7 +567,8 @@ static int set_expected_rtp(struct sk_buff *skb,
}

static int process_sdp(struct sk_buff *skb,
const char **dptr, unsigned int *datalen)
const char **dptr, unsigned int *datalen,
unsigned int cseq)
{
enum ip_conntrack_info ctinfo;
struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
Expand Down Expand Up @@ -600,6 +602,96 @@ static int process_sdp(struct sk_buff *skb,

return set_expected_rtp(skb, dptr, datalen, &addr, htons(port));
}
static int process_invite_response(struct sk_buff *skb,
const char **dptr, unsigned int *datalen,
unsigned int cseq, unsigned int code)
{
if ((code >= 100 && code <= 199) ||
(code >= 200 && code <= 299))
return process_sdp(skb, dptr, datalen, cseq);

return NF_ACCEPT;
}

static int process_update_response(struct sk_buff *skb,
const char **dptr, unsigned int *datalen,
unsigned int cseq, unsigned int code)
{
if ((code >= 100 && code <= 199) ||
(code >= 200 && code <= 299))
return process_sdp(skb, dptr, datalen, cseq);

return NF_ACCEPT;
}

static const struct sip_handler sip_handlers[] = {
SIP_HANDLER("INVITE", process_sdp, process_invite_response),
SIP_HANDLER("UPDATE", process_sdp, process_update_response),
};

static int process_sip_response(struct sk_buff *skb,
const char **dptr, unsigned int *datalen)
{
static const struct sip_handler *handler;
enum ip_conntrack_info ctinfo;
struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
unsigned int matchoff, matchlen;
unsigned int code, cseq, dataoff, i;

if (*datalen < strlen("SIP/2.0 200"))
return NF_ACCEPT;
code = simple_strtoul(*dptr + strlen("SIP/2.0 "), NULL, 10);
if (!code)
return NF_DROP;

if (ct_sip_get_header(ct, *dptr, 0, *datalen, SIP_HDR_CSEQ,
&matchoff, &matchlen) <= 0)
return NF_DROP;
cseq = simple_strtoul(*dptr + matchoff, NULL, 10);
if (!cseq)
return NF_DROP;
dataoff = matchoff + matchlen + 1;

for (i = 0; i < ARRAY_SIZE(sip_handlers); i++) {
handler = &sip_handlers[i];
if (handler->response == NULL)
continue;
if (*datalen < dataoff + handler->len ||
strnicmp(*dptr + dataoff, handler->method, handler->len))
continue;
return handler->response(skb, dptr, datalen, cseq, code);
}
return NF_ACCEPT;
}

static int process_sip_request(struct sk_buff *skb,
const char **dptr, unsigned int *datalen)
{
static const struct sip_handler *handler;
enum ip_conntrack_info ctinfo;
struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
unsigned int matchoff, matchlen;
unsigned int cseq, i;

for (i = 0; i < ARRAY_SIZE(sip_handlers); i++) {
handler = &sip_handlers[i];
if (handler->request == NULL)
continue;
if (*datalen < handler->len ||
strnicmp(*dptr, handler->method, handler->len))
continue;

if (ct_sip_get_header(ct, *dptr, 0, *datalen, SIP_HDR_CSEQ,
&matchoff, &matchlen) <= 0)
return NF_DROP;
cseq = simple_strtoul(*dptr + matchoff, NULL, 10);
if (!cseq)
return NF_DROP;

return handler->request(skb, dptr, datalen, cseq);
}
return NF_ACCEPT;
}

static int sip_help(struct sk_buff *skb,
unsigned int protoff,
Expand Down Expand Up @@ -634,15 +726,10 @@ static int sip_help(struct sk_buff *skb,
if (datalen < strlen("SIP/2.0 200"))
return NF_ACCEPT;

/* RTP info only in some SDP pkts */
if (strnicmp(dptr, "INVITE", strlen("INVITE")) != 0 &&
strnicmp(dptr, "UPDATE", strlen("UPDATE")) != 0 &&
strnicmp(dptr, "SIP/2.0 180", strlen("SIP/2.0 180")) != 0 &&
strnicmp(dptr, "SIP/2.0 183", strlen("SIP/2.0 183")) != 0 &&
strnicmp(dptr, "SIP/2.0 200", strlen("SIP/2.0 200")) != 0)
return NF_ACCEPT;

return process_sdp(skb, &dptr, &datalen);
if (strnicmp(dptr, "SIP/2.0 ", strlen("SIP/2.0 ")) != 0)
return process_sip_request(skb, &dptr, &datalen);
else
return process_sip_response(skb, &dptr, &datalen);
}

static struct nf_conntrack_helper sip[MAX_PORTS][2] __read_mostly;
Expand Down

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