[NETFILTER]: nf_conntrack_sip: support method specific request/response 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>
diff --git a/net/netfilter/nf_conntrack_sip.c b/net/netfilter/nf_conntrack_sip.c
index 96bedb52..1be949f 100644
--- a/net/netfilter/nf_conntrack_sip.c
+++ b/net/netfilter/nf_conntrack_sip.c
@@ -212,6 +212,7 @@
* 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),
@@ -566,7 +567,8 @@
}
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);
@@ -600,6 +602,96 @@
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,
@@ -634,15 +726,10 @@
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;