The Serving-CSCF Module (scscf)

Module Documentation

[Overview] [Code Structure] [Configuration and usage] [Example]

Overview

This module is supposed to provide the functionality required for an Serving-CSCF

To use it you need the The CDiameterPeer Module (cdp) loaded. This is because this module communicates using Diameter with the Home Subscriber Server over the IMS_Cx inteface.

Code Structure

Configuration and usage

For exported functions look at scscf_cmds.
For configuration parameters look at scscf_params.

Example

And here is a real usage example:

• Serving-CSCF configuration file

  #
  # $Id: scscf.cfg 571 2008-07-02 12:00:17Z vingarzan $
  #
  # Serving - CSCF configuration script
  #
  
  # ----------- global configuration parameters ------------------------
  
  debug=3
  log_stderror=yes
  memlog=5
  sip_warning=yes
  
  fork=yes
  children=4
  
  
  listen=127.0.0.1
  port=6060
  alias=scscf.open-ims.test:6060
  
  check_via=no        # (cmd. line: -v)
  dns=no          # (cmd. line: -r)
  rev_dns=no      # (cmd. line: -R)
  
  # ------------------ module loading ----------------------------------
  
  loadmodule "/opt/OpenIMSCore/ser_ims/modules/sl/sl.so"
  
  loadmodule "/opt/OpenIMSCore/ser_ims/modules/tm/tm.so"
  
  loadmodule "/opt/OpenIMSCore/ser_ims/modules/dialog/dialog.so"
  
  
  loadmodule "/opt/OpenIMSCore/ser_ims/modules/rr/rr.so"
  loadmodule "/opt/OpenIMSCore/ser_ims/modules/maxfwd/maxfwd.so"
  loadmodule "/opt/OpenIMSCore/ser_ims/modules/textops/textops.so"
  loadmodule "/opt/OpenIMSCore/ser_ims/modules/enum/enum.so"
  
  loadmodule "/opt/OpenIMSCore/ser_ims/modules/scscf/scscf.so"
  
  modparam("scscf","name","sip:scscf.open-ims.test:6060")
  
  #Comment the following line to allow for realm routing on the Cx interface
  #modparam("scscf","forced_hss_peer","hss.open-ims.test")
  
  modparam("scscf","auth_data_hash_size",64)
  modparam("scscf","auth_vector_timeout",60)
  modparam("scscf","auth_data_timeout",60)
  modparam("scscf","av_request_at_once",1)
  modparam("scscf","av_request_at_sync",1)
  
  modparam("scscf","server_assignment_store_data",0)
  
  # only one of user_data validation file should normaly be declared here
  # because if both are specified the data will be checked twice
  #modparam("scscf","user_data_dtd","/opt/OpenIMSCore/ser_ims/modules/scscf/CxDataType.dtd")
  modparam("scscf","user_data_xsd","/opt/OpenIMSCore/ser_ims/modules/scscf/CxDataType_Rel7.xsd")
  
  modparam("scscf","registrar_hash_size",256)
  
  modparam("scscf","registration_default_expires",3600)
  modparam("scscf","registration_min_expires",30)
  modparam("scscf","registration_max_expires",1000000)
  
  modparam("scscf","registration_default_algorithm","AKAv1-MD5")
  #modparam("scscf","registration_default_algorithm","AKAv2-MD5")
  #modparam("scscf","registration_default_algorithm","MD5")
  #modparam("scscf","registration_default_algorithm","CableLabs-Digest")
  #modparam("scscf","registration_default_algorithm","TISPAN-HTTP_DIGEST_MD5")
  # Let the HSS decide
  #modparam("scscf","registration_default_algorithm","HSS-Selected")
  
  # The next authentication methods are implemented here but not yet completed in FHoSS
  # please do not complain about bugs when using with FHoSS, yet!
  #modparam("scscf","registration_default_algorithm","NASS-Bundled")
  
  modparam("scscf","registration_disable_early_ims",1)
  modparam("scscf","registration_disable_nass_bundled",1)
  
  modparam("scscf","subscription_default_expires",3600)
  modparam("scscf","subscription_min_expires",30)
  modparam("scscf","subscription_max_expires",1000000)
  
  modparam("scscf","dialogs_hash_size",256)
  modparam("scscf","dialogs_expiration_time",3600)
  modparam("scscf","dialogs_enable_release",1)
  modparam("scscf","max_dialog_count",20000)
  modparam("scscf","min_se",90)
  
  # persistency_mode - 0 None / 1 Files / 2 Databases
  modparam("scscf","persistency_mode",0)
  
  # support for wildcard PSI 0 No 1 Yes
  modparam("scscf","support_wildcardPSI",0)
  
  #modparam("scscf","persistency_mode",1)
  #modparam("scscf","persistency_location","/opt/OpenIMSCore/persistency")
  #modparam("scscf","persistency_timer_authdata",60)
  #modparam("scscf","persistency_timer_dialogs",60)
  #modparam("scscf","persistency_timer_registrar",60)
  
  
  loadmodule "/opt/OpenIMSCore/ser_ims/modules/isc/isc.so"
  
  modparam("isc","my_uri","scscf.open-ims.test:6060")
  modparam("isc","isc_fr_timeout",5000)
  modparam("isc","isc_fr_inv_timeout",20000)
  modparam("isc","expires_grace",120)
  
  
  loadmodule "/opt/OpenIMSCore/ser_ims/modules/cdp/cdp.so"
  modparam("cdp","config_file","/opt/OpenIMSCore/scscf.xml")
  
  # add value to ;lr param to make some broken UAs happy
  modparam("rr", "enable_full_lr", 1)
  
  
  
  # -------------------------  request routing logic -------------------
  
  # main routing logic
  
  route{
  
      route(Sanity_Checks);
  
      # don't repeat work for a transaction already in processing
      if (method!="ACK" && S_trans_in_processing()) {
          log(1,"Trans already in processing... skip\n");
          break;
      }
      
      if (method=="REGISTER") {
          route(REGISTER);
          break;
      }
  
      if (method=="SUBSCRIBE" && search("^(Event|o)([ \t]*):([ \t]*)reg")) {
          route(SUBSCRIBE);
          break;
      }
      
      if (method=="ACK") {
          loose_route();
          t_relay();
          exit;
      }
          
      if (S_mobile_originating()||ISC_from_AS("orig")){
          # support for AS origination on behalf of unregistered user
          if (S_orig_not_registered()) {
              S_assign_server_unreg("open-ims.test", "orig");
          }
      
          # Originating
          route(Orig);
          break;              
      }else{
          if (S_is_in_dialog("orig")){
              route(Orig_Subsequent);
              break;
          }
          if (S_is_in_dialog("term")){
              route(Term_Subsequent);
              break;
          }       
          
          # Terminating
          if (uri=~"sip:(.*)@open-ims\.test(.*)" || uri=~"tel:.*"){
              if (S_term_not_registered())
                  S_assign_server_unreg("open-ims.test", "term");
          }else{
              sl_send_reply("403","Forbidden - Dialog not found on S-CSCF or Terminating user not suitable for unregistered services");
              exit();
          } 
          
          route(Term);
              
          break;
      }
  
  }
  
  route[Sanity_Checks]
  {
      # initial sanity checks -- messages with
      # max_forwards==0, or excessively long requests
      if (!mf_process_maxfwd_header("10")) {
          sl_send_reply("483","Too Many Hops");
          exit;
      };
      
      if (msg:len >=  max_len ) {
          sl_send_reply("513", "Message too big");
          exit;
      };
  
      if(@hf_value.max_forwards=="0"){
          
          exit;
      }
  }
  
  route[Check_Session_Expires]
  {
      if (!S_check_session_expires()) {
          S_422_session_expires();
          exit;
      };      
  }
  
  route[REGISTER]
  {
      if (uri=~"sip:(.*)open-ims\.test(.*)"){
          t_newtran();
  #       if ( !t_newtran()) {
  #           sl_reply_error();
  #           break;
  #       };
      
          if (!S_is_integrity_protected("open-ims.test")){
              # Unprotected REGISTER
              # Variant 1 - accept also non IPSec clients
              if (!S_is_authorized("open-ims.test")) {
                  S_challenge("open-ims.test");
                  route(Service_Routes);
                  t_reply("401", "Unauthorized - Challenging the UE");
                  exit;
              }else{
                  if (S_is_not_registered()){
                      if (S_assign_server("open-ims.test")){
                          route(Service_Routes);
                          route(Charging_Function_Addresses);
                          t_reply("200","OK - SAR succesful and registrar saved");
                          ISC_match_filter_reg("0");
                          exit;
                      }else{
                          t_reply("500","Server Internal Error - Server Assignment failed");
                          exit;
                      }
                  }else{
                      ISC_match_filter_reg("1");
                      if (S_assign_server("open-ims.test")){
                          route(Service_Routes);
                          route(Charging_Function_Addresses);
                          t_reply("200","OK - SAR succesful and registrar saved");
                          exit;
                      }else{
                          t_reply("500","Server Internal Error - Server Assignment failed");
                          exit;
                      }
                  }
              }
              
              # Variant 2 - accept only IPSec clients
              #S_challenge("open-ims.test");
              #route(Service_Routes);
              #t_reply("401", "Unauthorized - Challenging the UE");
              
              break;
          }else{
              # Protected REGISTER
              
              # Variant 1 - Always require reauthentication
              #if (!S_is_authorized("open-ims.test")) {
              #   S_challenge("open-ims.test");
              #   route(Service_Routes);
              #   t_reply("401", "Unauthorized - Challenging the UE");
              #   exit;
              #}
  
              # Variant 2 - trust protected REGISTER
              if (S_is_not_registered()){
                  if (S_assign_server("open-ims.test")){
                      route(Service_Routes);
                      route(Charging_Function_Addresses);                 
                      t_reply("200","OK - SAR succesful and registrar saved");
                      ISC_match_filter_reg("0");                  
                      exit;
                  }else{
                      t_reply("500","Server Internal Error - Server Assignment failed");
                      exit;
                  }
              }else{
                  ISC_match_filter_reg("1");
                  if (S_assign_server("open-ims.test")){
                      route(Service_Routes);
                      route(Charging_Function_Addresses);                 
                      t_reply("200","OK - SAR succesful and registrar saved");
                      exit;
                  }else{
                      t_reply("500","Server Internal Error - Update Contacts failed");
                      exit;
                  }
              }
          }
      } else {
          sl_send_reply("403", "Forbidden - Domain not serviced");
      }
  }
  
  route[Service_Routes]
  {
  #   if (!S_check_visited_network_id("open-ims\.test")){
  #       S_add_service_route("sip:thig@icscf.open-ims.test");
  #   }
      S_add_path_service_routes();
      S_add_allow("INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, SUBSCRIBE, NOTIFY, PUBLISH, MESSAGE, INFO");
  }   
  
  route[Charging_Function_Addresses]
  {
      if (S_check_visited_network_id("open-ims\.test")){
          S_add_p_charging_function_addresses();
      }
  }   
  
  route[SUBSCRIBE]
  {
      if ( !t_newtran()) {
          sl_reply_error();
          break;
      }   
      if (!S_term_registered()){
          t_reply("404","Not Found - User not registered on this S-CSCF");
          exit;
      }
      if (S_can_subscribe()){
          if (S_subscribe()){
              # This is replied from S_subscribe, as that also add extra headers
              #t_reply("200","OK - Subscription saved");
              
              exit;
          }else{
              t_reply("500","Server Error saving subscription");
              exit;
          }
      }else{
          t_reply("403","Forbidden to SUBSCRIBE");
          exit;
      };
  }
  
  
  
  
  
  
  
  #           ORIGINATING
  
  
  
  
  
  
  route[Orig]
  {
      log(1,">>       Orig\n");
      if (S_originating_barred()){
          sl_send_reply("403","Forbidden - Originating Public Identity barred");
          exit;
      }
      if (method=="INVITE"||method=="SUBSCRIBE"){
          route(Check_Session_Expires);
          
          if (!S_is_record_routed("orig"))
              S_record_route("orig");
  
          if (!S_save_dialog("orig")){
              sl_send_reply("514","Originating dialog save failure - S-CSCF maximum dialog count reached!");
              exit;
          }
      }
  
      loose_route();
      
      S_privacy_hook();
  
      # check if dialog saved as fwded to AS
      if (ISC_match_filter("orig")){
          t_on_reply("ISC_Orig_reply");
          t_on_failure("ISC_Orig_failure");   
          log(1,">>       Orig - msg was fwded to AS\n");
              exit;
      }
      
      # if THIG_required -> add THIG route
  
      if (!ISC_from_AS("orig")){
          S_add_p_asserted_identity();
      }
          
  
  
      if (method=="INVITE") {
          route(PSTN_handling);
      }   
  
      t_on_reply("Orig_reply");
      #t_on_failure("Orig_failure");
      
      # Do not loop through the I-CSCF if the terminating user is here
      # might not work if other routes are present
      if (S_term_registered()){
          t_relay_to_udp("127.0.0.1",6060);
          exit;
      }
      
      if (!t_relay()) {
          sl_send_reply("500","Error forwarding towards terminating leg");
          exit;
      };
  }
  
  onreply_route[Orig_reply]
  {
      log(1,">>       Orig_reply\n");
      if (!S_update_dialog("orig")){
          log(1,">>       Error updating orig dialog - maybe non-dialog request...\n");
      }
  }
  
  failure_route[Orig_failure]
  {
      log(1,">>       Orig_failure\n");
  }
  
  onreply_route[ISC_Orig_reply]
  {
      log(1,">>       ISC_Orig_reply\n");
      if (!S_update_dialog("orig")){
          log(1,">>       Error updating orig dialog - maybe non-dialog request...\n");
      }
      break;
  }
  
  failure_route[ISC_Orig_failure]
  {
      log(1,">>       ISC_Orig_failure\n");
  #   if (t_check_status("408")) {
  #       if (ISC_is_session_continued()){
  #           log(1,">>   ISC continue session not implemented :(\n");
  #           break;      
  #       }else{
  #           t_reply("555","AS failed to respond");
  #       }
  #   }
  
      if (t_check_status("408")||t_check_status("5..")){
          t_on_reply("ISC_Orig_reply");
          t_on_failure("ISC_Orig_failure");   
          if (ISC_match_filter("orig")){
              log(1,">>       ISC_Orig_failure - msg was fwded to AS\n");
                  exit;
          }
      
          # if THIG_required -> add THIG route
      
          if (!ISC_from_AS("origfail")){
              S_add_p_asserted_identity();
          }
          
          if (method=="INVITE") {
              route(PSTN_handling);
          }
      
          t_on_reply("Orig_reply");
          t_on_failure("Orig_failure");
          
          # Do not loop through the I-CSCF if the terminating user is here
          # might not work if other routes are present
          if (S_term_registered()){
              append_branch();
              t_relay_to_udp("127.0.0.1",6060);
              exit;
          }
      
          if (!t_relay()) {
              append_branch();    
              if (!t_relay()) {
                  t_reply("500","Error forwarding towards terminating leg");
                  exit;
              }
          };
      }
  }
  
  
  route[Orig_Subsequent]
  {
      log(1,">>       Orig_Subsequent\n");
      
      
      loose_route();
      if (method=="INVITE"){
          route(Check_Session_Expires);   
          S_update_dialog("orig");                
      }
      #S_record_route("orig");
      if (method!="ACK"){
          S_privacy_hook();
          t_on_reply("Orig_Subsequent_reply");
          #t_on_failure("Orig_Subsequent_failure");
      }
      if (!t_relay()) {
          sl_send_reply("500","Error forwarding subsequent request towards terminating leg");
          exit;
      };
  }
  
  onreply_route[Orig_Subsequent_reply]
  {
      log(1,">>       Orig_Subsequent_reply\n");
  #   if (t_check_status("305")){
  #       S_proxy_request();
  #       break;
  #   }
      S_update_dialog("orig");
      break;
  }
  
  failure_route[Orig_Subsequent_failure]
  {
      log(1,">>       Orig_Subsequent_failure\n");
  }
              
  
  
  
  
  #               TERMINATING
  
  
  route[Term]
  {
      log(1,">>       Term\n");
  
      if (S_terminating_barred()){
          sl_send_reply("404","Not Found - Terminating user barred");
          exit;
      }
      
      if (method=="INVITE"||method=="SUBSCRIBE"){
          route(Check_Session_Expires);
          if (!S_is_record_routed("term"))
              S_record_route("term");
  
          if (!S_save_dialog("term")){
              sl_send_reply("514","Terminating dialog save failure - S-CSCF maximum dialog count reached!");
              exit;
          }
      }
  
      loose_route();
  
      # check if dialog saved as fwded to AS
      if (ISC_match_filter("term")){
          t_on_reply("ISC_Term_reply");
          t_on_failure("ISC_Term_failure");   
          log(1,">>       Term - msg was fwded to AS\n");
          exit;
      }
      
      if (!S_lookup()){
          if (uri=~"sip:(.*)@open-ims\.test(.*)") {
              if ( !t_newtran()) {
                  sl_reply_error();
                  exit;
              };              
              t_reply("404","Not Found - destination user not found on this S-CSCF");
              exit;
          }       
      }
  
  
      t_on_reply("Term_reply");
      #t_on_failure("Term_failure");
      
      S_apply_privacy();
  
      if (!t_relay()) {
          sl_send_reply("500","Error forwarding towards terminating leg");
          exit;
      };
  }
  
  
  onreply_route[Term_reply]
  {
      log(1,">>       Term_reply\n");
      if (!S_update_dialog("term")){
          log(1,">>       Error updating term dialog - maybe non-dialog request...\n");
      }
  }
  
  failure_route[Term_failure]
  {
      log(1,">>       Term_failure\n");
  }
  
  onreply_route[ISC_Term_reply]
  {
      log(1,">>       ISC_Term_reply\n");
      if (!S_update_dialog("term")){
          log(1,">>       Error updating term dialog - maybe non-dialog request...\n");
      }
      break;
  }
  
  failure_route[ISC_Term_failure]
  {
      log(1,">>       ISC_Term_failure\n");
  #   if (t_check_status("408")) {
  #       if (ISC_is_session_continued()){
  #           log(1,">>   ISC continue session not implemented :(\n");
  #           break;      
  #       }else{
  #           t_reply("555","AS failed to respond");
  #       }
  #   }
  
      if (t_check_status("408")||t_check_status("5..")){
          t_on_reply("ISC_Term_reply");
          t_on_failure("ISC_Term_failure");   
          if (ISC_match_filter("term")){
              log(1,">>       Term - msg was fwded to AS\n");
              exit;
          }
  
          if (!S_lookup()){
              if (uri=~"sip:(.*)@open-ims\.test(.*)") {
                  #if ( !t_newtran()) {
                  #   sl_reply_error();
                  #   exit;
                  #};             
                  t_reply("404","Not Found - destination user not found on this S-CSCF");
                  exit;
              }       
          }
      
          t_on_reply("Term_reply");
          t_on_failure("Term_failure");
      
          if (!t_relay()) {
              append_branch();
              if (!t_relay()) {
                  t_reply("500","Error forwarding towards terminating leg");
                  exit;
              }
          };
      }
  }
  
  route[Term_Subsequent]
  {
      log(1,">>       Term_Subsequent\n");
      loose_route();
      if (method=="INVITE"){
          route(Check_Session_Expires);       
          S_update_dialog("term");                
      }
      
      S_apply_privacy();
      
      #S_record_route("term");
      
      if (method!="ACK") {
          t_on_reply("Term_Subsequent_reply");
          #t_on_failure("Term_Subsequent_failure");
      }   
      if (!t_relay()) {
          sl_send_reply("500","Error forwarding subsequent request towards user");
          exit;
      };
  }
  
  onreply_route[Term_Subsequent_reply]
  {
      log(1,">>       Term_Subsequent_reply\n");
  #   if (t_check_status("305")){
  #       S_proxy_request();
  #       break;
  #   }
      S_update_dialog("term");
      break;      
  }
  
  failure_route[Term_Subsequent_failure]
  {
      log(1,">>       Term_Subsequent_failure\n");
  }
  
  
  
  
  
  
  route[PSTN_handling]
  {
      #PSTN gateway handling
      if (uri=~"tel:\+(.*)"){
          if(!enum_query()){
              route(PSTN);
              break;
          }
      }
  
      #if (uri=~"sip:[0-9]+@open-ims\.test(.*)"){
      #   route(PSTN);
      #   break;
      #}
  
      # a tel URI in non-international format (i.e. the local service number analysis and handling is either failed in the appropriate AS or the request has not been forwarded to AS for local service number analysis and handling at all)
      if (uri=~"tel:[^+]*") {
          route(PSTN);
          break;
      }
  
      # a SIP URI with the user part starting with a + and user=phone
      if (uri=~"sip:\+[0-9]+@open-ims\.test.*user=phone.*"){
          route(PSTN);
          break;
      }
  }
  
  route[PSTN]
  {
      t_on_reply("PSTN_reply"); 
      t_relay_to_udp("127.0.0.1", "9060");
      exit;
  }
  
  onreply_route[PSTN_reply]
  {
      log(1,">>       PSTN_reply\n");
      if (!S_update_dialog("orig")){
          log(1,">>       Error updating orig dialog - maybe non-dialog request...\n");
      }
  }
  

Author:

Dragos Vingarzan vingarzan -at- fokus dot fraunhofer dot de

---