- Added handling of Max-Forwards header

- a detected via loop results in an 482 Loop detected

ChangeLog

@@ -1,6 +1,8 @@
 0.5.3
 =====
-   31-Jan-2004:	- Allow 2 of my vias in header to let 2 UA's sitting
+   1-Feb-2004:	- Added handling of Max-Forwards header
+		- a detected via loop results in an 482 Loop detected
+  31-Jan-2004:	- Allow 2 of my vias in header to let 2 UA's sitting
 		  behind the same siproxd to have conversation together
                   UA1 -->--\       /-->--\
                             siproxd       Registrar
@@ -22,19 +24,20 @@
 
 0.5.2
 =====
-   30-Jan-2004:	- If RTP proxy is disabled, don't rewrite incomming
+  31-Jan-2004:	- Released 0.5.2
+  30-Jan-2004:	- If RTP proxy is disabled, don't rewrite incomming
 		  SDP bodies (patch from Robert Högberg)
-   29-Jan-2004:	- new doc/RFC3261_compliance.txt and comments in the
+  29-Jan-2004:	- new doc/RFC3261_compliance.txt and comments in the
 		  code that refer to the RFC.
-   28-Jan-2004:	- don't die on INVITE requests that include no Contact
+  28-Jan-2004:	- don't die on INVITE requests that include no Contact
                   header - which is legal. (patch from Robert Högberg)
 		- RTP proxy: don't try to forward empty RTP packets
 		- renamed some variables of rtp_proxytable_t to make
                   better sense (changed meaning in fullduplex RTP proxy)
-   27-Jan-2004:	- added doc/KNOWN_BUGS
+  27-Jan-2004:	- added doc/KNOWN_BUGS
 		- better branch parameter calculation (via header),
                   now honors RFC3261 for stateless proxies (section 16.11)
-                - SIP request: remove a Route-header pointing to myself.
+                - SIP request: remove a Route header pointing to myself.
                   This was an issue with Linphone 0.12.1.
                   (patch from Robert Högberg).
                 - removed IPCHAINS & IPTABLES (netfilter) proxy support
@@ -42,13 +45,13 @@
                   use one single port (and socket) on each side (inbound/
                   outbound) to send and receive RTP traffic for every
                   active stream (patch from Christof Meerwald).
-   22-Jan-2004:	- ./configure option: --enable-static to build
+  22-Jan-2004:	- ./configure option: --enable-static to build
 		  a completely statically linked executable
                 - REGISTER honors the expires parameter
                   of the contact header
                 - Contact header of REGISTER response must be
                   rewritten back to the local (true) URL
-   18-Jan-2004:	- security_check_raw:
+  18-Jan-2004:	- security_check_raw:
 		  size check: >= 16 bytes
                 - at exit, check registration file to be writable
                 - no WARNING if SIP user-agent header is not supplied.
@@ -57,6 +60,7 @@
 
 0.5.1
 =====
+  22-Dec-2003:	- Released 0.5.1
   21-Dec-2003:	- possibility to log call establishment
   17-Dec-2003:	- full duplex RTP proxy (many thanks to Chris Ross for
 		  his work on this). Up to now, only the RTP *Relay*

TODO

@@ -22,31 +22,9 @@ TODOs, in random order:
 
 - via loop detection: send 482 error code
 
-- support Record-Route header
 
 - feature: don't bind to 0.0.0.0 address, but only to inbound/outbound IF's
   (defined by IFNAME)
 
-- support IPTABLES for RTP proxying -> use libiptc
+RFC3261 non-compliance:
-
+- Record-Route header handling
-- rtpproxy_masq:
-  RACE CONDITIONS! A slot may be timed out, even if the actual
-  masquerading tunnel is still active. A following new
-  INVITE then tries to use the believed free port -> Buh
-  - Can we poll (/proc/something) to figure out if the tunnel
-    is still active before deleting? This would require knowledge
-    of the text layout in /proc/xxx.
-  - are there some other possibilities (netfilter/libiptc)?
-  - introduce some kind of connection STATE to the proxy table.
-    Timeout based discarding only is active for non-established.
-    An INVITE would set the STATE to CONNECTING, the following
-    ACK to CONNECTED. A CONNECTED entry can only be deleted by
-    a BYE or CANCEL.
-  - NETFILTER: during startup (RTP initialization) siproxd should
-    clean left over entries that are within the RTP proxy port range
-- NETFILTER masquerading: 
-  it looks like it is not possible to create an entry in the
-  ip_conntrack table from an userspace application. How do we proceed?
-  We just might insert/delete DNAT entries in the PREROUTE NAT table.
-  This the means that we must implement a connection state into the
-  proxy table.

doc/RFC3261_compliance.txt

@@ -9,19 +9,19 @@ Request Processing:					implemented
   Section 16.3:  Request Validation
     1. Reasonable Syntax					yes
     2. URI scheme						no
-    3. Max-Forwards						no
+    3. Max-Forwards						yes
-    4. (Optional) Loop Detection				partially
+    4. (Optional) Loop Detection				yes
     5. Proxy-Require						no
     6. Proxy-Authorization					yes
 
-  Section 16.4 Route Information Preprocessing			yes
+  Section 16.4 Route Information Preprocessing			partially
 
   Section 16.5 Determining Request Targets			no
 
   Section 16.6 Request Forwarding
     1.  Make a copy of the received request			yes
     2.  Update the Request-URI					yes
-    3.  Update the Max-Forwards header field			no
+    3.  Update the Max-Forwards header field			yes
     4.  Optionally add a Record-route header field value	no
     5.  Optionally add additional header fields			no
     6.  Postprocess routing information				no
@@ -37,7 +37,7 @@ Response Processing:					implemented
     1. Reasonable Syntax					yes
     2. URI scheme						no
     3. Max-Forwards						no
-    4. (Optional) Loop Detection				partially
+    4. (Optional) Loop Detection				yes
     5. Proxy-Require						no
     6. Proxy-Authorization					yes
 

src/proxy.c

@@ -91,47 +91,26 @@ int proxy_request (osip_message_t *request, struct sockaddr_in *from) {
 
    DEBUGC(DBCLASS_PROXY,"proxy_request");
 
-   /*
-    * RFC 3261, Section 16.6 step 1
-    * Proxy Behavior - Request Forwarding - Make a copy
-    */
-   /* nothing to do here, copy is ready in 'request'*/
 
    /*
-    * RFC 3261, Section 16.6 step 3
+    * RFC 3261, Section 16.4
-    * Proxy Behavior - Request Forwarding - Max-Forwards
-    * (if Max-Forward header exists, decrement by one, if it does not
-    * exist, add a new one with value SHOULD be 70)
-    */
-   /* NOT IMPLEMENTED */
-
-   /*
-    * RFC 3261, Section 16.6 step 4
-    * Proxy Behavior - Request Forwarding - Add a Record-route header
-    */
-   /* NOT IMPLEMENTED (optional) */
-
-   /*
-    * RFC 3261, Section 16.6 step 5
-    * Proxy Behavior - Request Forwarding - Add Additional Header Fields
-    */
-   /* NOT IMPLEMENTED (optional) */
-
-   /*
-    * RFC 3261, Section 16.6 step 6
-    * Proxy Behavior - Request Forwarding - Postprocess routing information
-    */
-   /* NOT IMPLEMENTED */
-
-
-   /*
-    * RFC 3261, Section 16.4 
     * Proxy Behavior - Route Information Preprocessing
-    * (process Record-Route header)
+    * (process Route header)
     */
+/*
+   The proxy MUST inspect the Request-URI of the request.  If the
+   Request-URI of the request contains a value this proxy previously
+   placed into a Record-Route header field (see Section 16.6 item 4),
+   the proxy MUST replace the Request-URI in the request with the last
+   value from the Route header field, and remove that value from the
+   Route header field.  The proxy MUST then proceed as if it received
+   this modified request.
+
+   NOT IMPLEMENTED*/
    /*
     * Check if I am listed at the topmost Route header (if any Route
-    * header is existing at all). If so, remove it from the list.
+    * header is existing at all). If so, remove it from the list and
+    * rewrite the request URI to point to the now topmost Route.
     */
    if (request->routes && !osip_list_eol(request->routes, 0)) {
       struct in_addr addr1, addr2, addr3;
@@ -151,7 +130,8 @@ int proxy_request (osip_message_t *request, struct sockaddr_in *from) {
                configuration.sip_listen_port == SIP_PORT)) {
          osip_list_remove(request->routes, 0);
          osip_route_free(route);
-         /* possibly request->routes will be freed by osip_message_free() */
+         /* request->routes will be freed by osip_message_free() */
+         DEBUGC(DBCLASS_PROXY,"removed Route header pointing to myself");
       }
    }
       
@@ -298,6 +278,11 @@ int proxy_request (osip_message_t *request, struct sockaddr_in *from) {
    } /* log_calls */
 
 
+   /*
+    * RFC 3261, Section 16.6 step 1
+    * Proxy Behavior - Request Forwarding - Make a copy
+    */
+   /* nothing to do here, copy is ready in 'request'*/
 
    /* get destination address */
    url=osip_message_get_uri(request);
@@ -321,17 +306,6 @@ int proxy_request (osip_message_t *request, struct sockaddr_in *from) {
          proxy_rewrite_request_uri(request, i);
       }
 
-      /*
-       * RFC 3261, Section 16.6 step 8
-       * Proxy Behavior - Add a Via header field value
-       */
-      /* add my Via header line (inbound interface)*/
-      sts = sip_add_myvia(request, IF_INBOUND);
-      if (sts == STS_FAILURE) {
-         ERROR("adding my inbound via failed!");
-         return STS_FAILURE;
-      }
-
       /* if this is CANCEL/BYE request, stop RTP proxying */
       if (MSG_IS_BYE(request) || MSG_IS_CANCEL(request)) {
          /* stop the RTP proxying stream(s) */
@@ -356,7 +330,7 @@ int proxy_request (osip_message_t *request, struct sockaddr_in *from) {
   /*
    * from the internal masqueraded host to an external host
    */
-   case  REQTYP_OUTGOING:
+   case REQTYP_OUTGOING:
       DEBUGC(DBCLASS_PROXY,"outgoing request from %s@%s from inbound",
 	request->from->url->username? request->from->url->username:"*NULL*",
         request->from->url->host? request->from->url->host: "*NULL*");
@@ -371,6 +345,9 @@ int proxy_request (osip_message_t *request, struct sockaddr_in *from) {
       /* if it is addressed to myself, then it must be some request
        * method that I as a proxy do not support. Reject */
 #if 0
+/* careful - an internal UA might send an request to another internal UA.
+   This would be caught here, so don't do this. This situation should be
+   caught in the default part of the CASE statement below */
       if (is_sipuri_local(request) == STS_TRUE) {
          WARN("unsupported request [%s] directed to proxy from %s@%s -> %s@%s",
 	    request->sip_method? request->sip_method:"*NULL*",
@@ -393,16 +370,6 @@ int proxy_request (osip_message_t *request, struct sockaddr_in *from) {
       /* rewrite Contact header to represent the masqued address */
       sip_rewrite_contact(request, DIR_OUTGOING);
 
-      /*
-       * RFC 3261, Section 16.8
-       * Proxy Behavior - Add a Via header field value
-       */
-      /* add my Via header line (outbound interface)*/
-      sts = sip_add_myvia(request, IF_OUTBOUND);
-      if (sts == STS_FAILURE) {
-         ERROR("adding my outbound via failed!");
-      }
-
       /* if this is CANCEL/BYE request, stop RTP proxying */
       if (MSG_IS_BYE(request) || MSG_IS_CANCEL(request)) {
          /* stop the RTP proxying stream(s) */
@@ -438,10 +405,119 @@ int proxy_request (osip_message_t *request, struct sockaddr_in *from) {
       return STS_FAILURE;
    }
 
-  /*
+
-   * RFC 3261, Section 16.6 step 7
+   /*
-   * Proxy Behavior - Determine Next-Hop Address
+    * RFC 3261, Section 16.6 step 3
-   */
+    * Proxy Behavior - Request Forwarding - Max-Forwards
+    * (if Max-Forwards header exists, decrement by one, if it does not
+    * exist, add a new one with value SHOULD be 70)
+    */
+   {
+   osip_header_t *max_forwards;
+   int forwards_count = DEFAULT_MAXFWD;
+   char mfwd[8];
+
+   osip_message_get_max_forwards(request, 0, &max_forwards);
+   if (max_forwards == NULL) {
+      sprintf(mfwd, "%i", forwards_count);
+      osip_message_set_max_forwards(request, mfwd);
+   } else {
+      if (max_forwards->hvalue) {
+         forwards_count = atoi(max_forwards->hvalue);
+         forwards_count -=1;
+         osip_free (max_forwards->hvalue);
+      }
+
+      sprintf(mfwd, "%i", forwards_count);
+      max_forwards->hvalue = osip_strdup(mfwd);
+   }
+
+   DEBUGC(DBCLASS_PROXY,"setting Max-Forwards=%s",mfwd);
+   }
+
+   /*
+    * RFC 3261, Section 16.6 step 4
+    * Proxy Behavior - Request Forwarding - Add a Record-route header
+    */
+#if 0
+/* NOT IMPLEMENTED - this requires proper implementation of
+   the Route headers first. */
+   {
+   struct in_addr addr;
+   osip_record_route_t *r_route;
+   osip_uri_t *uri_of_proxy;
+
+   /*
+    * get the IP address of the interface where I'm going to
+    * send out this request
+    */
+   switch (type) {
+   case REQTYP_INCOMING:
+      sts = get_ip_by_ifname(configuration.inbound_if, &addr);
+      if (sts == STS_FAILURE) {
+         ERROR("can't find inbound interface %s - configuration error?",
+               configuration.outbound_if);
+         return STS_FAILURE;
+      }
+      break;
+   case REQTYP_OUTGOING:
+      sts = get_ip_by_ifname(configuration.outbound_if, &addr);
+      if (sts == STS_FAILURE) {
+         ERROR("can't find outbound interface %s - configuration error?",
+               configuration.outbound_if);
+         return STS_FAILURE;
+      }
+      break;
+   default:
+      ERROR("Oops, never should end up here (type=%i)", type);
+      return STS_FAILURE;
+   }
+
+   sts = osip_record_route_init(&r_route);
+   if (sts == 0) {
+      sts = osip_uri_init(&uri_of_proxy);
+      if (sts == 0) {
+         char tmp[8];
+
+         /* host name / IP */
+         osip_uri_set_host(uri_of_proxy, osip_strdup(utils_inet_ntoa(addr)));
+
+         /* port number */
+         sprintf(tmp, "%i", configuration.sip_listen_port);
+         osip_uri_set_port(uri_of_proxy, osip_strdup(tmp));
+
+         /* 'lr' parameter */
+         osip_uri_uparam_add(uri_of_proxy, "lr", NULL);
+
+         osip_record_route_set_url(r_route, uri_of_proxy);
+
+         /* insert before all other record-route */
+         osip_list_add (request->record_routes, r_route, 0);
+      } else {
+          osip_record_route_free (r_route);
+          osip_free (r_route);
+      } /* if url_init */
+   } /* if record route init */
+
+   }
+#endif
+
+   /*
+    * RFC 3261, Section 16.6 step 5
+    * Proxy Behavior - Request Forwarding - Add Additional Header Fields
+    */
+   /* NOT IMPLEMENTED (optional) */
+
+
+   /*
+    * RFC 3261, Section 16.6 step 6
+    * Proxy Behavior - Request Forwarding - Postprocess routing information
+    */
+
+   /*
+    * RFC 3261, Section 16.6 step 7
+    * Proxy Behavior - Determine Next-Hop Address
+    */
    if ((type == REQTYP_OUTGOING) && (configuration.outbound_proxy_host)) {
       /* I have an outbound proxy configured */
       sts = get_ip_by_host(configuration.outbound_proxy_host, &sendto_addr);
@@ -472,6 +548,23 @@ int proxy_request (osip_message_t *request, struct sockaddr_in *from) {
       }
    }
 
+   /*
+    * RFC 3261, Section 16.6 step 8
+    * Proxy Behavior - Add a Via header field value
+    */
+   /* add my Via header line (outbound interface)*/
+   if (type == REQTYP_INCOMING) {
+      sts = sip_add_myvia(request, IF_INBOUND);
+      if (sts == STS_FAILURE) {
+         ERROR("adding my inbound via failed!");
+      }
+   } else {
+      sts = sip_add_myvia(request, IF_OUTBOUND);
+      if (sts == STS_FAILURE) {
+         ERROR("adding my outbound via failed!");
+         return STS_FAILURE;
+      }
+   }
   /*
    * RFC 3261, Section 16.6 step 9
    * Proxy Behavior - Add a Content-Length header field if necessary

src/register.c

@@ -215,10 +215,9 @@ int register_client(osip_message_t *my_msg, int force_lcl_masq) {
    * look for an Contact expires parameter - in case of REGISTER
    * these two are equal. The Contact expires has higher priority!
    */
-
    osip_contact_param_get_byname(
            (osip_contact_t*) my_msg->contacts->node->element,
-           "expires", &expires_param);
+           EXPIRES, &expires_param);
 
    if (expires_param && expires_param->gvalue) {
       /* get expires from contact Header */

src/siproxd.c

@@ -294,9 +294,25 @@ int main (int argc, char *argv[])
       /*
        * RFC 3261, Section 16.3 step 3
        * Proxy Behavior - Request Validation - Max-Forwards check
-       * (check Max-Forward header and refuse with 483 if too many hops)
+       * (check Max-Forwards header and refuse with 483 if too many hops)
        */
-      /* NOT IMPLEMENTED */
+      {
+      osip_header_t *max_forwards;
+      int forwards_count = DEFAULT_MAXFWD;
+
+      osip_message_get_max_forwards(my_msg, 0, &max_forwards);
+      if (max_forwards && max_forwards->hvalue) {
+         forwards_count = atoi(max_forwards->hvalue);
+      }
+
+      DEBUGC(DBCLASS_PROXY,"checking Max-Forwards (=%i)",forwards_count);
+      if (forwards_count <= 0) {
+         DEBUGC(DBCLASS_SIP, "Forward count reached 0 -> 483 response");
+         sip_gen_response(my_msg, 483 /*Too many hops*/);
+         goto end_loop; /* skip and free resources */
+      }
+
+      }
 
       /*
        * RFC 3261, Section 16.3 step 4
@@ -304,8 +320,8 @@ int main (int argc, char *argv[])
        * (check for loop and return 482 if a loop is detected)
        */
       if (check_vialoop(my_msg) == STS_TRUE) {
-         DEBUGC(DBCLASS_PROXY,"via loop detected, ignoring request");
+         DEBUGC(DBCLASS_SIP,"via loop detected, ignoring request");
-         /* we should return 482, NOT IMPLEMENTED */
+         sip_gen_response(my_msg, 482 /*Loop detected*/);
          goto end_loop; /* skip and free resources */
       }
 

src/siproxd.h

@@ -156,7 +156,8 @@ struct siproxd_config {
 /*
  * some constant definitions
  */
-#define SIP_PORT	5060
+#define SIP_PORT	5060	/* default port to listen */
+#define DEFAULT_MAXFWD	70	/* default Max-Forward count */
 
 #define URLMAP_SIZE	32	/* number of URL mapping table entries	*/
 #define RTPPROXY_SIZE	64	/* number of rtp proxy entries		*/