initial checkin of the sbc module

The SBC application is a highly flexible high-performance Back-to-Back User Agent (B2BUA). It can be employed for a variety of uses, for example topology hiding, From/To modification, enforcing SIP Session Timers, identity change, SIP authentication. Future uses include accounting, call timers, RTP call bridging, transcoding, call distribution.
15 years ago · f86ac8e0ff
parent 17502bbcde
commit f86ac8e0ff
14 changed files with 1599 additions and 11 deletions
--- a/apps/sbc/CMakeLists.txt
+++ b/apps/sbc/CMakeLists.txt
@ -0,0 +1,6 @@
+set (sbc_SRCS
+SBC.cpp
+)
+
+SET(sems_module_name sbc)
+INCLUDE(${CMAKE_SOURCE_DIR}/cmake/module.rules.txt)
--- a/apps/sbc/HeaderFilter.cpp
+++ b/apps/sbc/HeaderFilter.cpp
@ -0,0 +1,178 @@
+/*
+ * Copyright (C) 2010 Stefan Sayer
+ *
+ * This file is part of SEMS, a free SIP media server.
+ *
+ * SEMS is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * For a license to use the SEMS software under conditions
+ * other than those described here, or to purchase support for this
+ * software, please contact iptel.org by e-mail at the following addresses:
+ *    info@iptel.org
+ *
+ * SEMS is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#include "HeaderFilter.h"
+#include "sip/parse_common.h"
+#include "log.h"
+const char* FilterType2String(FilterType ft) {
+    switch(ft) {
+    case Transparent: return "transparent";
+    case Whitelist: return "whitelist";
+    case Blacklist: return "blacklist";
+    default: return "unknown";
+    };
+}
+
+int skip_header(const std::string& hdr, size_t start_pos, 
+		 size_t& name_end, size_t& val_begin,
+		 size_t& val_end, size_t& hdr_end) {
+    // adapted from sip/parse_header.cpp
+
+    name_end = val_begin = val_end = start_pos;
+    hdr_end = hdr.length();
+
+    //
+    // Header states
+    //
+    enum {
+	H_NAME=0,
+	H_HCOLON,
+	H_VALUE_SWS,
+	H_VALUE,
+    };
+
+    int st = H_NAME;
+    int saved_st = 0;
+
+    
+    size_t p = start_pos;
+    for(;p<hdr.length() && st != ST_LF && st != ST_CRLF;p++){
+
+	switch(st){
+
+	case H_NAME:
+	    switch(hdr[p]){
+
+	    case_CR_LF;
+
+	    case HCOLON:
+		st = H_VALUE_SWS;
+		name_end = p;
+		break;
+
+	    case SP:
+	    case HTAB:
+		st = H_HCOLON;
+		name_end = p;
+		break;
+	    }
+	    break;
+
+	case H_VALUE_SWS:
+	    switch(hdr[p]){
+
+		case_CR_LF;
+
+	    case SP:
+	    case HTAB:
+		break;
+
+	    default:
+		st = H_VALUE;
+		val_begin = p;
+		break;
+		
+	    };
+	    break;
+
+	case H_VALUE:
+	    switch(hdr[p]){
+		case_CR_LF;
+	    };
+	    if (st==ST_CR || st==ST_LF)
+		val_end = p;
+	    break;
+
+	case H_HCOLON:
+	    switch(hdr[p]){
+	    case HCOLON:
+		st = H_VALUE_SWS;
+		val_begin = p;
+		break;
+
+	    case SP:
+	    case HTAB:
+		break;
+
+	    default:
+		DBG("Missing ':' after header name\n");
+		return MALFORMED_SIP_MSG;
+	    }
+	    break;
+
+	case_ST_CR(hdr[p]);
+
+	    st = saved_st;
+	    hdr_end = p;
+	    break;
+	}
+    }
+    
+    hdr_end = p;
+    if (p==hdr.length() && st==H_VALUE) {
+	val_end = p;	
+    }
+    
+    return 0;
+}
+
+int inplaceHeaderFilter(string& hdrs, const set<string>& headerfilter_list, FilterType f_type) {
+    if (!hdrs.length() || f_type == Transparent)
+	return 0;
+
+    int res = 0;
+    size_t start_pos = 0;
+    while (start_pos<hdrs.length()) {
+	size_t name_end, val_begin, val_end, hdr_end;
+	if ((res = skip_header(hdrs, start_pos, name_end, val_begin,
+			       val_end, hdr_end)) != 0) {
+	    return res;
+	}
+	string hdr_name = hdrs.substr(start_pos, name_end-start_pos);
+	bool erase = false;
+	if (f_type == Whitelist) {
+	    erase = headerfilter_list.find(hdr_name)==headerfilter_list.end();
+	} else if (f_type == Blacklist) {
+	    erase = headerfilter_list.find(hdr_name)!=headerfilter_list.end();
+	}
+	if (erase) {
+	    DBG("erasing header '%s'\n", hdr_name.c_str());
+	    hdrs.erase(start_pos, hdr_end-start_pos);
+	} else {
+	    start_pos = hdr_end;
+	}
+    }
+
+    // todo: multi-line header support
+
+    return res;
+}
+
+/** EMACS **
+ * Local variables:
+ * mode: c++
+ * c-basic-offset: 4
+ * End:
+ */
--- a/apps/sbc/HeaderFilter.h
+++ b/apps/sbc/HeaderFilter.h
@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2010 Stefan Sayer
+ *
+ * This file is part of SEMS, a free SIP media server.
+ *
+ * SEMS is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * For a license to use the SEMS software under conditions
+ * other than those described here, or to purchase support for this
+ * software, please contact iptel.org by e-mail at the following addresses:
+ *    info@iptel.org
+ *
+ * SEMS is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+#ifndef _HeaderFilter_h_
+#define _HeaderFilter_h_
+
+#include <string>
+using std::string;
+
+#include <set>
+using std::set;
+
+enum FilterType { Transparent=0, Whitelist, Blacklist };
+const char* FilterType2String(FilterType ft);
+int skip_header(const std::string& hdr, size_t start_pos, 
+		 size_t& name_end, size_t& val_begin, size_t& val_end, size_t& hdr_end);
+int inplaceHeaderFilter(string& hdrs, const set<string>& headerfilter_list, 
+			FilterType f_type);
+
+#endif
--- a/apps/sbc/Makefile
+++ b/apps/sbc/Makefile
@ -0,0 +1,7 @@
+plug_in_name = sbc
+
+module_ldflags =
+module_cflags  = -DMOD_NAME=\"$(plug_in_name)\"
+
+COREPATH ?= ../../core
+include $(COREPATH)/plug-in/Makefile.app_module
--- a/apps/sbc/SBC.cpp
+++ b/apps/sbc/SBC.cpp
@ -0,0 +1,762 @@
+/*
+ * $Id: SBC.cpp 1784 2010-04-15 13:01:00Z sayer $
+ *
+ * Copyright (C) 2010 Stefan Sayer
+ *
+ * This file is part of SEMS, a free SIP media server.
+ *
+ * SEMS is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * For a license to use the SEMS software under conditions
+ * other than those described here, or to purchase support for this
+ * software, please contact iptel.org by e-mail at the following addresses:
+ *    info@iptel.org
+ *
+ * SEMS is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+/* 
+SBC - feature-wishlist
+
+- SDP filter (reconstructed SDP)
+- maximum call duration timer
+- accounting (MySQL DB, cassandra DB)
+- RTP forwarding mode (bridging)
+- RTP transcoding mode (bridging)
+- overload handling (parallel call to target thresholds)
+- call distribution
+- select profile on monitoring in-mem DB record
+- fallback profile
+- add headers
+
+ */
+#include "SBC.h"
+
+#include "log.h"
+#include "AmUtils.h"
+#include "AmAudio.h"
+#include "AmPlugIn.h"
+#include "AmMediaProcessor.h"
+#include "AmConfigReader.h"
+#include "AmSessionContainer.h"
+#include "AmSipHeaders.h"
+
+#include "HeaderFilter.h"
+
+using std::map;
+
+string SBCFactory::user;
+string SBCFactory::domain;
+string SBCFactory::pwd;
+AmConfigReader SBCFactory::cfg;
+AmSessionEventHandlerFactory* SBCFactory::session_timer_fact = NULL;
+
+EXPORT_SESSION_FACTORY(SBCFactory,MOD_NAME);
+
+
+bool SBCCallProfile::readFromConfiguration(const string& name, const string profile_file_name) {
+  if (cfg.loadFile(profile_file_name)) {
+    ERROR("reading SBC call profile from '%s'\n", profile_file_name.c_str());
+    return false;
+  }
+
+  string hf_type = cfg.getParameter("header_filter", "transparent");
+  if (hf_type=="transparent")
+    headerfilter = Transparent;
+  else if (hf_type=="whitelist")
+    headerfilter = Whitelist;
+  else if (hf_type=="blacklist")
+    headerfilter = Blacklist;
+  else {
+    ERROR("invalid header_filter mode '%s'\n", hf_type.c_str());
+    return false;
+  }
+  
+  vector<string> elems = explode(cfg.getParameter("header_list"), ",");
+  for (vector<string>::iterator it=elems.begin(); it != elems.end(); it++)
+    headerfilter_list.insert(*it);
+
+  string mf_type = cfg.getParameter("message_filter", "transparent");
+  if (mf_type=="transparent")
+    messagefilter = Transparent;
+  else if (mf_type=="whitelist")
+    messagefilter = Whitelist;
+  else if (hf_type=="blacklist")
+    messagefilter = Blacklist;
+  else {
+    ERROR("invalid message_filter mode '%s'\n", mf_type.c_str());
+    return false;
+  }
+  
+  elems = explode(cfg.getParameter("message_list"), ",");
+  for (vector<string>::iterator it=elems.begin(); it != elems.end(); it++)
+    messagefilter_list.insert(*it);
+
+  sst_enabled = cfg.getParameter("enable_session_timer", "no") == "yes";
+  use_global_sst_config = !cfg.hasParameter("session_expires");
+  
+  auth_enabled = cfg.getParameter("enable_auth", "no") == "yes";
+  auth_credentials.user = cfg.getParameter("auth_user");
+  auth_credentials.pwd = cfg.getParameter("auth_pwd");
+
+  ruri = cfg.getParameter("RURI");
+  from = cfg.getParameter("From");
+  to = cfg.getParameter("To");
+
+  INFO("SBC: loaded SBC profile '%s':\n", name.c_str());
+
+  INFO("SBC:      RURI = '%s'\n", ruri.c_str());
+  INFO("SBC:      From = '%s'\n", from.c_str());
+  INFO("SBC:      To   = '%s'\n", to.c_str());
+  INFO("SBC:      header filter  is %s, %zd items in list\n",
+       FilterType2String(headerfilter), headerfilter_list.size());
+  INFO("SBC:      message filter is %s, %zd items in list\n",
+       FilterType2String(messagefilter), messagefilter_list.size());
+  INFO("SBC:      SST %sabled\n", sst_enabled?"en":"dis");
+  INFO("SBC:      SIP auth %sabled\n", auth_enabled?"en":"dis");
+  
+  return true;
+}
+
+SBCFactory::SBCFactory(const string& _app_name)
+: AmSessionFactory(_app_name)
+{
+}
+
+
+int SBCFactory::onLoad()
+{
+
+  if(cfg.loadFile(AmConfig::ModConfigPath + string(MOD_NAME ".conf"))) {
+    ERROR("No configuration for sbc present (%s)\n",
+	 (AmConfig::ModConfigPath + string(MOD_NAME ".conf")).c_str()
+	 );
+    return -1;
+  }
+
+  session_timer_fact = AmPlugIn::instance()->getFactory4Seh("session_timer");
+  if(!session_timer_fact) {
+    ERROR("could not load session_timer from session_timer plug-in\n");
+    return -1;
+  }
+
+  vector<string> profiles_names = explode(cfg.getParameter("profiles"), ",");
+  for (vector<string>::iterator it =
+	 profiles_names.begin(); it != profiles_names.end(); it++) {
+    string profile_file_name = AmConfig::ModConfigPath + *it + ".sbcprofile.conf";
+    if (!call_profiles[*it].readFromConfiguration(*it, profile_file_name)) {
+      ERROR("configuring SBC call profile from '%s'\n", profile_file_name.c_str());
+      return -1;
+    }
+  }
+
+  active_profile = cfg.getParameter("active_profile");
+  if (active_profile != "$(paramhdr)" &&
+      active_profile != "$(ruri.user)" &&
+      call_profiles.find(active_profile) == call_profiles.end()) {
+    ERROR("call profile active_profile '%s' not loaded!\n", active_profile.c_str());
+    return -1;
+  }
+
+  INFO("SBC: active profile: '%s'\n", active_profile.c_str());
+  return 0;
+}
+
+
+AmSession* SBCFactory::onInvite(const AmSipRequest& req)
+{
+  string profile = active_profile;
+  if (profile == "$(paramhdr)") {
+    string app_param = getHeader(req.hdrs, PARAM_HDR, true);
+    profile = get_header_keyvalue(app_param,"profile");
+  } else if (profile == "$(ruri.user)") {
+    profile = req.user;
+  }
+
+  map<string, SBCCallProfile>::iterator it=
+    call_profiles.find(profile);
+  if (it==call_profiles.end()) {
+    ERROR("could not find call profile '%s' (active_profile = %s)\n",
+	  profile.c_str(), active_profile.c_str());
+    throw AmSession::Exception(500,"Server Internal Error");
+  }
+
+  DBG("using call profile '%s'\n", profile.c_str());
+  SBCCallProfile& call_profile = it->second;
+  AmConfigReader& sst_cfg = call_profile.use_global_sst_config ?
+    cfg : call_profile.cfg; // override with profile config
+
+  if (call_profile.sst_enabled) {
+    DBG("Enabling SIP Session Timers\n");
+    if (!session_timer_fact->onInvite(req, sst_cfg))
+      return NULL;
+  }
+
+  SBCDialog* b2b_dlg = new SBCDialog(call_profile);
+
+  if (call_profile.sst_enabled) {
+    AmSessionEventHandler* h = session_timer_fact->getHandler(b2b_dlg);
+    if(!h) {
+      delete b2b_dlg;
+      ERROR("could not get a session timer event handler\n");
+      throw AmSession::Exception(500,"Server internal error");
+    }
+
+    if (h->configure(sst_cfg)){
+      ERROR("Could not configure the session timer: disabling session timers.\n");
+      delete h;
+    } else {
+      b2b_dlg->addHandler(h);
+    }
+  }
+
+  return b2b_dlg;
+}
+
+
+SBCDialog::SBCDialog(const SBCCallProfile& call_profile) // AmDynInvoke* user_timer)
+  : m_state(BB_Init),
+    call_profile(call_profile)
+{
+  set_sip_relay_only(false);
+}
+
+
+SBCDialog::~SBCDialog()
+{
+}
+
+void SBCDialog::replaceParsedParam(const string& s, size_t p,
+				   AmUriParser& parsed, string& res) {
+  switch (s[p+1]) {
+  case 'u': { // URI
+    res+=parsed.uri_user+"@"+parsed.uri_host;
+    if (!parsed.uri_port.empty())
+      res+=":"+parsed.uri_port;
+  } break;
+  case 'U': res+=parsed.uri_user; break; // User
+  case 'd': { // domain
+    res+=parsed.uri_host;
+    if (!parsed.uri_port.empty())
+      res+=":"+parsed.uri_port;
+  } break;
+  case 'h': res+=parsed.uri_host; break; // host
+  case 'p': res+=parsed.uri_port; break; // port
+  case 'H': res+=parsed.uri_headers; break; // Headers
+  case 'P': res+=parsed.uri_param; break; // Params
+  default: WARN("unknown replace pattern $%c%c\n",
+		s[p], s[p+1]); break;
+  };
+}
+
+
+string SBCDialog::replaceParameters(const char* r_type,
+				    const string& s, const AmSipRequest& req,
+				    const string& app_param,
+				    AmUriParser& ruri_parser, AmUriParser& from_parser,
+				    AmUriParser& to_parser) {
+  string res;
+  bool is_replaced = false;
+  size_t p = 0;
+  char last_char=' ';
+  
+  while (p<s.length()) {
+    size_t skip_chars = 1;
+    if (last_char=='\\') {
+      res += s[p];
+      is_replaced = true;
+    } else if (s[p]=='\\') {
+      if (p==s.length()-1)
+      res += s[p];
+    } else if ((s[p]=='$') && (s.length() >= p+1)) {
+      is_replaced = true;
+      p++;
+      switch (s[p]) {
+      case 'f': { // from
+	if ((s.length() == p+1) || (s[p+1] == '.')) {
+	  res += req.from;
+	  break;
+	}
+	  
+	if (from_parser.uri.empty()) {
+	  from_parser.uri = req.from;
+	  if (!from_parser.parse_uri()) {
+	    WARN("Error parsing From URI '%s'\n", req.from.c_str());
+	    break;
+	  }
+	}
+
+	replaceParsedParam(s, p, from_parser, res);
+
+      }; break;
+
+      case 't': { // to
+	if ((s.length() == p+1) || (s[p+1] == '.')) {
+	  res += req.to;
+	  break;
+	}
+
+	if (to_parser.uri.empty()) {
+	  to_parser.uri = req.to;
+	  if (!to_parser.parse_uri()) {
+	    WARN("Error parsing To URI '%s'\n", req.to.c_str());
+	    break;
+	  }
+	}
+
+	replaceParsedParam(s, p, to_parser, res);
+
+      }; break;
+
+      case 'r': { // r-uri
+	if ((s.length() == p+1) || (s[p+1] == '.')) {
+	  res += req.r_uri;
+	  break;
+	}
+	
+	if (ruri_parser.uri.empty()) {
+	  ruri_parser.uri = req.r_uri;
+	  if (!ruri_parser.parse_uri()) {
+	    WARN("Error parsing R-URI '%s'\n", req.r_uri.c_str());
+	    break;
+	  }
+	}
+	replaceParsedParam(s, p, ruri_parser, res);
+      }; break;
+
+#define case_HDR(pv_char, pv_name, hdr_name)				\
+	case pv_char: {							\
+	  AmUriParser uri_parser;					\
+	  uri_parser.uri = getHeader(req.hdrs, hdr_name);		\
+	  if ((s.length() == p+1) || (s[p+1] == '.')) {			\
+	    res += uri_parser.uri;					\
+	    break;							\
+	  }								\
+									\
+	  if (!uri_parser.parse_uri()) {				\
+	    WARN("Error parsing " pv_name " URI '%s'\n", uri_parser.uri.c_str()); \
+	    break;							\
+	  }								\
+	  if (s[p+1] == 'i') {						\
+	    res+=uri_parser.uri_user+"@"+uri_parser.uri_host;		\
+	    if (!uri_parser.uri_port.empty())				\
+	      res+=":"+uri_parser.uri_port;				\
+	  } else {							\
+	    replaceParsedParam(s, p, uri_parser, res);			\
+	  }								\
+	}; break;							
+
+	case_HDR('a', "PAI", SIP_HDR_P_ASSERTED_IDENTITY);  // P-Asserted-Identity
+	case_HDR('p', "PPI", SIP_HDR_P_PREFERRED_IDENTITY); // P-Preferred-Identity
+
+      case 'P': { // app-params
+	if (s[p+1] != '(') {
+	  WARN("Error parsing P param replacement (missing '(')\n");
+	  break;
+	}
+	if (s.length()<p+3) {
+	  WARN("Error parsing P param replacement (short string)\n");
+	  break;
+	}
+
+	size_t skip_p = p+2;
+	for (;skip_p<s.length() && s[skip_p] != ')';skip_p++) { }
+	if (skip_p==s.length()) {
+	  WARN("Error parsing P param replacement (unclosed brackets)\n");
+	  break;
+	}
+	string param_name = s.substr(p+2, skip_p-p-2);
+	// DBG("param_name = '%s' (skip-p - p = %d)\n", param_name.c_str(), skip_p-p);
+	res += get_header_keyvalue(app_param, param_name);
+	skip_chars = skip_p-p;
+      } break;
+
+      default: {
+	WARN("unknown replace pattern $%c%c\n",
+	     s[p], s[p+1]);
+      }; break;
+      };
+
+      p+=skip_chars; // skip $.X      
+    } else {
+      res += s[p];
+    }
+
+    last_char = s[p];
+    p++;
+  }
+
+  if (is_replaced) {
+    DBG("%s pattern replace: '%s' -> '%s'\n", r_type, s.c_str(), res.c_str());
+  }
+  return res;
+}
+
+void SBCDialog::onInvite(const AmSipRequest& req)
+{
+  AmUriParser ruri_parser, from_parser, to_parser;
+
+  DBG("processing initial INVITE\n");
+
+  if(dlg.reply(req, 100, "Connecting") != 0) {
+    throw AmSession::Exception(500,"Failed to reply 100");
+  }
+
+  string app_param = getHeader(req.hdrs, PARAM_HDR, true);
+
+  ruri = call_profile.ruri.empty() ? 
+    req.r_uri : replaceParameters("RURI", call_profile.ruri, req, app_param,
+				  ruri_parser, from_parser, to_parser);
+
+  from = call_profile.from.empty() ? 
+    req.from : replaceParameters("From", call_profile.from, req, app_param,
+				  ruri_parser, from_parser, to_parser);
+
+  to = call_profile.to.empty() ? 
+    req.to : replaceParameters("To", call_profile.to, req, app_param,
+				  ruri_parser, from_parser, to_parser);
+
+  m_state = BB_Dialing;
+
+  invite_req = req;
+
+  removeHeader(invite_req.hdrs,PARAM_HDR);
+  removeHeader(invite_req.hdrs,"P-App-Name");
+
+  if (call_profile.sst_enabled) {
+    removeHeader(invite_req.hdrs,SIP_HDR_SESSION_EXPIRES);
+    removeHeader(invite_req.hdrs,SIP_HDR_MIN_SE);
+  }
+
+  inplaceHeaderFilter(invite_req.hdrs, 
+		      call_profile.headerfilter_list, call_profile.headerfilter);
+
+  if (call_profile.auth_enabled) {
+    call_profile.auth_credentials.user = 
+      replaceParameters("auth_user", call_profile.auth_credentials.user, req, app_param,
+			ruri_parser, from_parser, to_parser);
+    call_profile.auth_credentials.pwd = 
+      replaceParameters("auth_pwd", call_profile.auth_credentials.pwd, req, app_param,
+			ruri_parser, from_parser, to_parser);
+  }
+
+  DBG("SBC: connecting to <%s>\n",ruri.c_str());
+  DBG("     From:  <%s>\n",from.c_str());
+  DBG("     To:  <%s>\n",to.c_str());
+  connectCallee(to, ruri, true);
+}
+
+void SBCDialog::process(AmEvent* ev)
+{
+  AmB2BCallerSession::process(ev);
+}
+
+void SBCDialog::relayEvent(AmEvent* ev) {
+  if (call_profile.headerfilter != Transparent) {
+    if (ev->event_id == B2BSipRequest) {
+      B2BSipRequestEvent* req_ev = dynamic_cast<B2BSipRequestEvent*>(ev);
+      assert(req_ev);
+      inplaceHeaderFilter(req_ev->req.hdrs, 
+			  call_profile.headerfilter_list, call_profile.headerfilter);
+    } else if (ev->event_id == B2BSipReply) {
+      B2BSipReplyEvent* reply_ev = dynamic_cast<B2BSipReplyEvent*>(ev);
+      assert(reply_ev);
+      inplaceHeaderFilter(reply_ev->reply.hdrs, 
+			  call_profile.headerfilter_list, call_profile.headerfilter);
+    }
+  }
+
+  AmB2BCallerSession::relayEvent(ev);
+}
+
+void SBCDialog::onSipRequest(const AmSipRequest& req) {
+  // AmB2BSession does not call AmSession::onSipRequest for 
+  // forwarded requests - so lets call event handlers here
+  // todo: this is a hack, replace this by calling proper session 
+  // event handler in AmB2BSession
+  bool fwd = sip_relay_only &&
+    (req.method != "BYE") &&
+    (req.method != "CANCEL");
+  if (fwd) {
+      CALL_EVENT_H(onSipRequest,req);
+  }
+
+  if (fwd && call_profile.messagefilter != Transparent) {
+    bool is_filtered = (call_profile.messagefilter == Whitelist) ^ 
+      (call_profile.messagefilter_list.find(req.method) != 
+       call_profile.messagefilter_list.end());
+    if (is_filtered) {
+      DBG("replying 405 to filtered message '%s'\n", req.method.c_str());
+      dlg.reply(req, 405, "Method Not Allowed", "", "", "", SIP_FLAGS_VERBATIM);
+      return;
+    }
+  }
+
+  AmB2BCallerSession::onSipRequest(req);
+}
+
+void SBCDialog::onSipReply(const AmSipReply& reply, int old_dlg_status,
+			      const string& trans_method)
+{
+  TransMap::iterator t = relayed_req.find(reply.cseq);
+  bool fwd = t != relayed_req.end();
+
+  DBG("onSipReply: %i %s (fwd=%i)\n",reply.code,reply.reason.c_str(),fwd);
+  DBG("onSipReply: content-type = %s\n",reply.content_type.c_str());
+  if (fwd) {
+      CALL_EVENT_H(onSipReply,reply, old_dlg_status, trans_method);
+  }
+
+  AmB2BCallerSession::onSipReply(reply,old_dlg_status, trans_method);
+}
+
+bool SBCDialog::onOtherReply(const AmSipReply& reply)
+{
+  bool ret = false;
+
+  if ((m_state == BB_Dialing) && (reply.cseq == invite_req.cseq)) {
+    if (reply.code < 200) {
+      DBG("Callee is trying... code %d\n", reply.code);
+    }
+    else if(reply.code < 300) {
+      if(getCalleeStatus()  == Connected) {
+        m_state = BB_Connected;
+      }
+    }
+    else if(reply.code == 487 && dlg.getStatus() == AmSipDialog::Pending) {
+      DBG("Stopping leg A on 487 from B with 487\n");
+      dlg.reply(invite_req, 487, "Request terminated");
+      setStopped();
+      ret = true;
+    }
+    else if (reply.code >= 300 && dlg.getStatus() == AmSipDialog::Connected) {
+      DBG("Callee final error in connected state with code %d\n",reply.code);
+      terminateLeg();
+    }
+    else {
+      DBG("Callee final error with code %d\n",reply.code);
+      AmB2BCallerSession::onOtherReply(reply);
+    }
+  }
+  return ret;
+}
+
+
+void SBCDialog::onOtherBye(const AmSipRequest& req)
+{
+//   stopAccounting();
+  AmB2BCallerSession::onOtherBye(req);
+}
+
+
+void SBCDialog::onBye(const AmSipRequest& req)
+{
+  if (m_state == BB_Connected) {
+//     stopAccounting();
+  }
+  terminateOtherLeg();
+  setStopped();
+}
+
+
+void SBCDialog::onCancel()
+{
+  if(dlg.getStatus() == AmSipDialog::Pending) {
+    DBG("Wait for leg B to terminate");
+  } else {
+    DBG("Canceling leg A on CANCEL since dialog is not pending");
+    dlg.reply(invite_req, 487, "Request terminated");
+    setStopped();
+  }
+}
+
+void SBCDialog::createCalleeSession()
+{
+  SBCCalleeSession* callee_session = new SBCCalleeSession(this, call_profile);
+  
+  if (call_profile.auth_enabled) {
+    // adding auth handler
+    AmSessionEventHandlerFactory* uac_auth_f = 
+      AmPlugIn::instance()->getFactory4Seh("uac_auth");
+    if (NULL == uac_auth_f)  {
+      INFO("uac_auth module not loaded. uac auth NOT enabled.\n");
+    } else {
+      AmSessionEventHandler* h = uac_auth_f->getHandler(callee_session);
+      
+      // we cannot use the generic AmSessionEventHandler hooks, 
+      // because the hooks don't work in AmB2BSession
+      callee_session->setAuthHandler(h);
+      DBG("uac auth enabled for callee session.\n");
+    }
+  }
+
+  if (call_profile.sst_enabled) {
+    AmSessionEventHandler* h = SBCFactory::session_timer_fact->getHandler(callee_session);
+    if(!h) {
+      ERROR("could not get a session timer event handler\n");
+      delete callee_session;
+      throw AmSession::Exception(500,"Server internal error");
+    }
+    AmConfigReader& sst_cfg = call_profile.use_global_sst_config ? 
+      SBCFactory::cfg: call_profile.cfg; // override with profile config
+
+    if(h->configure(sst_cfg)){
+      ERROR("Could not configure the session timer: disabling session timers.\n");
+      delete h;
+    } else {
+      callee_session->addHandler(h);
+    }
+  }
+
+  AmSipDialog& callee_dlg = callee_session->dlg;
+  
+  other_id = AmSession::getNewId();
+  
+  callee_dlg.local_tag    = other_id;
+  callee_dlg.callid       = AmSession::getNewId() + "@" + AmConfig::LocalIP;
+  
+  // this will be overwritten by ConnectLeg event 
+  callee_dlg.remote_party = to;
+  callee_dlg.remote_uri   = ruri;
+
+  callee_dlg.local_party  = from; 
+  callee_dlg.local_uri    = from; 
+  
+  DBG("Created B2BUA callee leg, From: %s\n",
+      from.c_str());
+
+  if (AmConfig::LogSessions) {
+    INFO("Starting B2B callee session %s app %s\n",
+	 callee_session->getLocalTag().c_str(), invite_req.cmd.c_str());
+  }
+
+  MONITORING_LOG5(other_id.c_str(), 
+		  "app",  invite_req.cmd.c_str(),
+		  "dir",  "out",
+		  "from", callee_dlg.local_party.c_str(),
+		  "to",   callee_dlg.remote_party.c_str(),
+		  "ruri", callee_dlg.remote_uri.c_str());
+
+  callee_session->start();
+  
+  AmSessionContainer* sess_cont = AmSessionContainer::instance();
+  sess_cont->addSession(other_id,callee_session);
+}
+
+SBCCalleeSession::SBCCalleeSession(const AmB2BCallerSession* caller,
+				   const SBCCallProfile& call_profile) 
+  : auth(NULL),
+    call_profile(call_profile),
+    AmB2BCalleeSession(caller) {
+}
+
+SBCCalleeSession::~SBCCalleeSession() {
+  if (auth) 
+    delete auth;
+}
+
+inline UACAuthCred* SBCCalleeSession::getCredentials() {
+  return &call_profile.auth_credentials;
+}
+
+void SBCCalleeSession::relayEvent(AmEvent* ev) {
+  if (call_profile.headerfilter != Transparent) {
+    if (ev->event_id == B2BSipRequest) {
+      B2BSipRequestEvent* req_ev = dynamic_cast<B2BSipRequestEvent*>(ev);
+      assert(req_ev);
+      inplaceHeaderFilter(req_ev->req.hdrs, 
+			  call_profile.headerfilter_list, call_profile.headerfilter);
+    } else if (ev->event_id == B2BSipReply) {
+      B2BSipReplyEvent* reply_ev = dynamic_cast<B2BSipReplyEvent*>(ev);
+      assert(reply_ev);
+      inplaceHeaderFilter(reply_ev->reply.hdrs, 
+			  call_profile.headerfilter_list, call_profile.headerfilter);
+    }
+  }
+
+  AmB2BCalleeSession::relayEvent(ev);
+}
+
+void SBCCalleeSession::onSipRequest(const AmSipRequest& req) {
+  // AmB2BSession does not call AmSession::onSipRequest for 
+  // forwarded requests - so lets call event handlers here
+  // todo: this is a hack, replace this by calling proper session 
+  // event handler in AmB2BSession
+  bool fwd = sip_relay_only &&
+    (req.method != "BYE") &&
+    (req.method != "CANCEL");
+  if (fwd) {
+      CALL_EVENT_H(onSipRequest,req);
+  }
+
+  if (fwd && call_profile.messagefilter != Transparent) {
+    bool is_filtered = (call_profile.messagefilter == Whitelist) ^ 
+      (call_profile.messagefilter_list.find(req.method) != 
+       call_profile.messagefilter_list.end());
+    if (is_filtered) {
+      DBG("replying 405 to filtered message '%s'\n", req.method.c_str());
+      dlg.reply(req, 405, "Method Not Allowed", "", "", "", SIP_FLAGS_VERBATIM);
+      return;
+    }
+  }
+
+  AmB2BCalleeSession::onSipRequest(req);
+}
+
+void SBCCalleeSession::onSipReply(const AmSipReply& reply, int old_dlg_status,
+				     const string& trans_method)
+{
+  // call event handlers where it is not done 
+  TransMap::iterator t = relayed_req.find(reply.cseq);
+  bool fwd = t != relayed_req.end();
+  DBG("onSipReply: %i %s (fwd=%i)\n",reply.code,reply.reason.c_str(),fwd);
+  DBG("onSipReply: content-type = %s\n",reply.content_type.c_str());
+  if(fwd) {
+    CALL_EVENT_H(onSipReply,reply, old_dlg_status, trans_method);
+  }
+
+  if (NULL == auth) {    
+    AmB2BCalleeSession::onSipReply(reply,old_dlg_status, trans_method);
+    return;
+  }
+  
+  unsigned int cseq_before = dlg.cseq;
+  if (!auth->onSipReply(reply, old_dlg_status, trans_method)) {
+      AmB2BCalleeSession::onSipReply(reply, old_dlg_status, trans_method);
+  } else {
+    if (cseq_before != dlg.cseq) {
+      DBG("uac_auth consumed reply with cseq %d and resent with cseq %d; "
+          "updating relayed_req map\n", 
+	  reply.cseq, cseq_before);
+      TransMap::iterator it=relayed_req.find(reply.cseq);
+      if (it != relayed_req.end()) {
+	relayed_req[cseq_before] = it->second;
+	relayed_req.erase(it);
+      }
+    }
+  }
+}
+
+void SBCCalleeSession::onSendRequest(const string& method, const string& content_type,
+				     const string& body, string& hdrs, int flags, unsigned int cseq)
+{
+  if (NULL != auth) {
+    DBG("auth->onSendRequest cseq = %d\n", cseq);
+    auth->onSendRequest(method, content_type,
+			body, hdrs, flags, cseq);
+  }
+  
+  AmB2BCalleeSession::onSendRequest(method, content_type,
+				     body, hdrs, flags, cseq);
+}
+
--- a/apps/sbc/SBC.h
+++ b/apps/sbc/SBC.h
@ -0,0 +1,174 @@
+/*
+ * Copyright (C) 2010 Stefan Sayer
+ *
+ * This file is part of SEMS, a free SIP media server.
+ *
+ * SEMS is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * For a license to use the SEMS software under conditions
+ * other than those described here, or to purchase support for this
+ * software, please contact iptel.org by e-mail at the following addresses:
+ *    info@iptel.org
+ *
+ * SEMS is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#ifndef _SBC_H
+#define _SBC_H
+
+#include "AmB2BSession.h"
+#include "ampi/UACAuthAPI.h"
+
+#include "AmConfigReader.h"
+#include "AmUriParser.h"
+#include "HeaderFilter.h"
+
+#include <map>
+
+using std::string;
+
+
+struct SBCCallProfile {
+
+  AmConfigReader cfg;
+
+  FilterType headerfilter;
+  set<string> headerfilter_list;
+
+  FilterType messagefilter;
+  set<string> messagefilter_list;
+
+  bool sst_enabled;
+  bool use_global_sst_config;
+
+  bool auth_enabled;
+  UACAuthCred auth_credentials;
+
+  string ruri;       /* updated if set */
+  string from;       /* updated if set */
+  string to;         /* updated if set */
+
+  // todo: call duration timer
+  // todo: accounting
+  // todo: RTP forwarding mode
+  // todo: RTP transcoding mode
+
+  SBCCallProfile()
+  : headerfilter(Transparent),
+    messagefilter(Transparent),
+    sst_enabled(false),
+    auth_enabled(false)
+  { }
+
+  bool readFromConfiguration(const string& name, const string profile_file_name);
+};
+
+class SBCFactory: public AmSessionFactory
+{
+/*   AmDynInvokeFactory* user_timer_fact; */
+
+  std::map<string, SBCCallProfile> call_profiles;
+  std::map<string, AmConfigReader> call_profiles_configs;
+
+  string active_profile;
+
+ public:
+  SBCFactory(const string& _app_name);
+  
+  int onLoad();
+  AmSession* onInvite(const AmSipRequest& req);
+  static string user;
+  static string domain;
+  static string pwd;
+
+  static AmConfigReader cfg;
+  static AmSessionEventHandlerFactory* session_timer_fact;
+};
+
+class SBCDialog : public AmB2BCallerSession
+{
+  enum {
+    BB_Init = 0,
+    BB_Dialing,
+    BB_Connected,
+    BB_Teardown
+  } CallerState;
+
+  int m_state;
+
+  string ruri;
+  string from;
+  string to;
+
+  /*   AmDynInvoke* m_user_timer; */
+
+  SBCCallProfile call_profile;
+
+  void replaceParsedParam(const string& s, size_t p,
+			  AmUriParser& parsed, string& res);
+
+  string replaceParameters(const char* r_type, const string& s, const AmSipRequest& req,
+			   const string& app_param,
+			   AmUriParser& ruri_parser, AmUriParser& from_parser,
+			   AmUriParser& to_parser);
+
+ public:
+
+  SBCDialog(const SBCCallProfile& call_profile); //AmDynInvoke* user_timer);
+  ~SBCDialog();
+  
+  void process(AmEvent* ev);
+  void onBye(const AmSipRequest& req);
+  void onInvite(const AmSipRequest& req);
+  void onCancel();
+
+ protected:
+  void relayEvent(AmEvent* ev);
+
+  void onSipReply(const AmSipReply& reply, int old_dlg_status,
+		  const string& trans_method);
+  void onSipRequest(const AmSipRequest& req);  
+
+  bool onOtherReply(const AmSipReply& reply);
+  void onOtherBye(const AmSipRequest& req);
+
+  void createCalleeSession();
+};
+
+class SBCCalleeSession 
+: public AmB2BCalleeSession, public CredentialHolder
+{
+  AmSessionEventHandler* auth;
+  SBCCallProfile call_profile;
+
+ protected:
+  void relayEvent(AmEvent* ev);
+
+  void onSipRequest(const AmSipRequest& req);
+  void onSipReply(const AmSipReply& reply, int old_dlg_status,
+		  const string& trans_method);
+  void onSendRequest(const string& method, const string& content_type,
+		     const string& body, string& hdrs, int flags, unsigned int cseq);
+
+  /* bool onOtherReply(const AmSipReply& reply); */
+
+ public:
+  SBCCalleeSession(const AmB2BCallerSession* caller,
+		   const SBCCallProfile& call_profile); 
+  ~SBCCalleeSession();
+
+  inline UACAuthCred* getCredentials();
+  
+  void setAuthHandler(AmSessionEventHandler* h) { auth = h; }
+};
+#endif                           
--- a/apps/sbc/etc/auth_b2b.sbcprofile.conf
+++ b/apps/sbc/etc/auth_b2b.sbcprofile.conf
@ -0,0 +1,76 @@
+# auth_b2b SBC profile
+#
+# This implements the identity change and SIP
+# authentication known from auth_b2b app.
+# For a more detailed description see the 
+# explanation below.
+#
+# A P-App-Param header is expected of the form:
+#   P-App-Param: u=<user>;d=<domain>;p=<pwd>
+# The INVITE is then sent from <user>@<domain>
+# to ruri-user@<domain>
+#
+# if the user/domain/password should be set here
+# in the configuration, replace $P(u), $P(p) and $P(d)
+# below.
+
+RURI=sip:$rU@$P(d)
+From="\"$P(u)\" <sip:$P(u)@$P(d)>"
+To="\"$rU\" <sip:$rU@$P(d)>"
+
+enable_auth=yes
+auth_user=$P(u)
+auth_pwd=$P(p)
+
+header_filter=blacklist
+header_list=P-App-Param,P-App-Name
+message_filter=transparent
+#message_list=
+
+# set this for session timer:
+#enable_session_timer=yes
+#session_expires=120
+#minimum_timer=90
+#session_refresh_method=UPDATE_FALLBACK_INVITE
+#accept_501_reply=yes
+
+
+#This profile implements a pure B2BUA application that does an
+#identity change and authenticates on the second leg of the call,
+#like this
+#
+#Caller            SEMS auth_b2b                123@domainb
+#  |                     |                        |
+#  | INVITE bob@domaina  |                        |
+#  | From: alice@domaina |                        |
+#  | To: bob@domaina     |                        |
+#  | P-App-Param:u=user;d=domainb;p=passwd        |
+#  |-------------------->|                        |
+#  |                     |INVITE bob@domainb      |
+#  |                     |From: user@domainb      |
+#  |                     |To: bob@domainb         |
+#  |                     |----------------------->|
+#  |                     |                        |
+#  |                     |  407 auth required     |
+#  |                     |<---------------------- |
+#  |                     |                        |
+#  |                     |                        |
+#  |                     | INVITE w/ auth         |
+#  |                     |----------------------->|
+#  |                     |                        |
+#  |                     |  100 trying            |
+#  |  100 trying         |<---------------------- |
+#  |<--------------------|                        |
+#  |                     |                        |
+#  |                     |  200 OK                |
+#  |  200 OK             |<---------------------- |
+#  |<--------------------|                        |
+#  |                     |                        |
+#  | ACK                 |                        |
+#  |-------------------->| ACK                    |
+#  |                     |----------------------->|
+#
+#App-Param:
+#  u - user in B leg
+#  d - domain in B leg
+#  p - password for auth in B leg (auth user=user)
--- a/apps/sbc/etc/sbc.conf
+++ b/apps/sbc/etc/sbc.conf
@ -0,0 +1,51 @@
+
+# profiles - comma-separated list of call profiles to load
+#
+# <name>.sbcprofile.conf is loaded from module config 
+# path (the path where this file resides)
+profiles=transparent,auth_b2b,sst_b2b
+
+# active call profile
+#
+# o active_profile=<profile_name>  always use <profile_name>
+#
+# o active_profile=$(ruri.user)    use user part of INVITE Request URI
+#
+# o active_profile=$(paramhdr)     use  "profile" option in P-App-Param header
+#
+active_profile=transparent
+
+
+## RFC4028 Session Timer
+# default configuration - can be overridden by call profiles
+
+# - enables the session timer ([yes,no]; default: no)
+#
+#enable_session_timer=yes
+
+# - set the "Session-Expires" parameter for the session timer.
+#
+# session_expires=240
+
+# - set the "Min-SE" parameter for the session timer.
+#
+# minimum_timer=90
+
+# session refresh (Session Timer, RFC4028) method
+#
+# INVITE                 - use re-INVITE
+# UPDATE                 - use UPDATE
+# UPDATE_FALLBACK_INVITE - use UPDATE if indicated in Allow, re-INVITE otherwise
+#
+# Default: UPDATE_FALLBACK_INVITE
+#
+# Note: Session Timers are only supported in some applications
+#
+#session_refresh_method=UPDATE
+
+# accept_501_reply - accept 501 reply as successful refresh? [yes|no]
+#
+# Default: yes
+#
+#accept_501_reply=no
+
--- a/apps/sbc/etc/sbc.conf.cmake
+++ b/apps/sbc/etc/sbc.conf.cmake
@ -0,0 +1,39 @@
+# RFC4028 Session Timer
+#
+
+# - enables the session timer ([yes,no]; default: no)
+#
+enable_session_timer=yes
+
+# - set the "Session-Expires" parameter for the session timer.
+#
+# session_expires=240
+
+# - set the "Min-SE" parameter for the session timer.
+#
+# minimum_timer=90
+
+# session refresh (Session Timer, RFC4028) method
+#
+# INVITE                 - use re-INVITE
+# UPDATE                 - use UPDATE
+# UPDATE_FALLBACK_INVITE - use UPDATE if indicated in Allow, re-INVITE otherwise
+#
+# Default: UPDATE_FALLBACK_INVITE
+#
+# Note: Session Timers are only supported in some applications
+#
+#session_refresh_method=UPDATE
+
+# accept_501_reply - accept 501 reply as successful refresh? [yes|no]
+#
+# Default: yes
+#
+#accept_501_reply=no
+
+######################################################
+#authentication (questionable whether that works)
+# user=someuser
+# domain=somedomain.net
+# pwd=sompwd
+
--- a/apps/sbc/etc/sst_b2b.sbcprofile.conf
+++ b/apps/sbc/etc/sst_b2b.sbcprofile.conf
@ -0,0 +1,53 @@
+# sst_b2b SBC profile
+#
+# This implements a transparent B2BUA with
+# SIP Session Timers known from the sst_b2b app.
+# Also see the description below.
+
+# defaults: transparent
+#RURI=$r
+#From=$f
+#To=$t
+
+## filters: 
+#header_filter=blacklist
+#header_list=P-App-Param,P-App-Name
+#message_filter=transparent
+#message_list=
+
+## authentication:
+#enable_auth=yes
+#auth_user=$P(u)
+#auth_pwd=$P(p)
+
+## session timer:
+enable_session_timer=yes
+# if session_expires is not configured here,
+# the values from sbc.conf are used, or the
+# default values
+#session_expires=120
+#minimum_timer=90
+#session_refresh_method=UPDATE_FALLBACK_INVITE
+#accept_501_reply=yes
+
+#
+#This application can be routed through for achieving 
+#two things: 
+#
+#  1. Forcing SIP Session Timers, which prevents 
+#     overbilling for calls where BYE is missing,
+#     for example in cases where media (RTP) path 
+#     does not go through the system, but billing 
+#     is still done.
+#
+#  2. Topology hiding; this application acts as 
+#     B2BUA, so on the B leg, no routing info from 
+#     the A leg can be seen.
+#
+#The incoming INVITE for a newly established call is 
+#passed in signaling only B2B mode to the B leg, 
+#which tries to send it to the request URI.
+#
+#SIP Session Timers are enabled on both legs. The
+#session refresh method may be configured; UPDATE
+#or INVITE with last established SDP may be used.
--- a/apps/sbc/etc/transparent.sbcprofile.conf
+++ b/apps/sbc/etc/transparent.sbcprofile.conf
@ -0,0 +1,29 @@
+# transparent SBC profile
+#
+# This implements a transparent B2BUA
+
+# defaults: transparent
+#RURI=$r
+#From=$f
+#To=$t
+
+## filters: 
+#header_filter=blacklist
+#header_list=P-App-Param,P-App-Name
+#message_filter=transparent
+#message_list=
+
+## authentication:
+#enable_auth=yes
+#auth_user=$P(u)
+#auth_pwd=$P(p)
+
+## session timer:
+#enable_session_timer=yes
+# if session_expires is not configured here,
+# the values from sbc.conf are used, or the
+# default values
+#session_expires=120
+#minimum_timer=90
+#session_refresh_method=UPDATE_FALLBACK_INVITE
+#accept_501_reply=yes
--- a/doc/Readme.auth_b2b.txt
+++ b/doc/Readme.auth_b2b.txt
@ -1,6 +1,14 @@

 auth_b2b application 

+-------------------------------------------------
+This application has been obsoleted by the sbc
+module and will be discontinued in the next version.
+Please use the sbc module with the auth_b2b call
+profile for the same functionality.
+-------------------------------------------------
+
+
 This module is a pure B2BUA application that does an identity 
 change and authenticates on the second leg of the call, like 
 this
--- a/doc/Readme.sbc.txt
+++ b/doc/Readme.sbc.txt
@ -0,0 +1,157 @@
+SBC module
+
+Copyright (C) 2010 Stefan Sayer
+
+Overview
+--------
+The SBC application is a highly flexible high-performance Back-to-Back
+User Agent (B2BUA). It can be employed for a variety of uses, for example 
+topology hiding, From/To modification, enforcing SIP Session Timers, 
+identity change, SIP authentication. Future uses include accounting,
+call timers, RTP call bridging, transcoding, call distribution.
+
+Features
+--------
+ o B2BUA
+ o flexible call profile based configuration
+ o From, To, RURI update
+ o Header and message filter
+ o SIP authentication
+ o SIP Session Timers
+
+SBC Profiles
+------------
+All features are set in an SBC profile, which is configured in a separate
+configuration file with the extension .sbcprofile.conf. Several SBC profiles
+may be loaded at startup (load_profiles), and can be selected with the 
+active_profile configuration option
+
+ o statically (active_profile=<profile_name>)
+
+ o depending on user part of INVITE Request URI(active_profile=$(ruri.user))
+
+ o depending on "profile" option in P-App-Param header (active_profile=$(paramhdr))
+
+By using the latter two options, the SBC profile for the call can be selected in the
+proxy.
+
+RURI, From, To - Replacement patterns
+-------------------------------------
+In SBC profile the appearance of the outgoing INVITE request can be set,
+by setting RURI, From and To parameters. If any of those parameters is not
+set, the corresponding value of the incoming request is used.
+
+The values that are set can contain patterns, which are set to values taken
+from the incoming INVITE request. The syntax loosely follows sip-router's
+pseudo variables. Any of the RURI, From and To values can contain any elements,
+e.g. the request-URI can be set to the user part of the P-Asserted-Identity
+header combined with the host part of the To.
+
+The patterns which can be used are the following:
+
+  $r (or $r. if something follows) - R-URI
+  $f (or $f. if something follows) - From
+  $t (or $t. if something follows) - To
+  $a (or $a. if something follows) - P-Asserted-Identity
+  $p (or $p. if something follows) - P-Preferref-Identity
+
+  $fu  - From URI
+  $fU  - From User
+  $fd  - From domain (host:port)
+  $fh  - From host
+  $fp  - From port
+  $fH  - From headers
+  $fP  - From Params
+
+  $tu  - To URI
+  $fU  - To User
+  ...
+
+  $ru  - R-URI URI
+  $rU  - R-URI User
+  ...
+
+  $ai  - P-Asserted-Identity URI
+  $au  - P-Asserted-Identity URI
+  $aU  - P-Asserted-Identity URI
+  ...
+
+  $pi  - P-Preferred-Identity URI
+  $pu  - P-Preferred-Identity URI
+  $pU  - P-Preferred-Identity User
+  ...
+
+
+  $P(paramname) - paramname from P-App-Param
+    Example:
+      P-App-Param: u=myuser;p=mypwd;d=mydomain
+        and
+      auth_user=$P(u)
+      auth_pwd=$P(p)
+      From=sip:$P(u)@$P(d)
+
+  \\  -> \
+  \$  -> $
+  \*  -> *
+
+If a quotation mark (") is used, it needs to be escaped with a backslash in
+the sbc profile configuration file.
+ Example: 
+   From="\"Anonymous\" <sip:anonymous@invalid>"
+
+If a space is contained, use quotation at the beginning and end.
+ Example:
+   To="\"someone\" <$aU@mytodomain.com>"
+
+Filters
+-------
+Headers and messages may be filtered. A filter can be set to 
+ o transparent - no filtering done
+
+ o whitelist - only let items pass that are in the filter list
+
+ o blacklist - filter out items that are in the filter list
+
+Note that if ACK messages should not be filtered.
+
+Session Timer configuration
+---------------------------
+If SIP Session Timers are enabled for a profile, the session timers values
+(session_refresh, minimum_timer etc) can be configured either in sbc.conf
+or in the profile configuration. The profile SST configuration is used if
+session_expires is set in the profile configuration file. 
+
+Note that for performance reasons the whole SST configuration is in this
+case used from the profile configuration (it is not overwritten value-by-value).
+
+Example profiles
+----------------
+ transparent   - completely transparent B2BUA
+ auth_b2b      - identity change and SIP authentication (obsoletes auth_b2b app)
+ sst_b2b       - B2BUA with SIP Session Timers (obsoletes sst_b2b app)
+
+Dependencies
+------------
+For SIP authentication: uac_auth module
+For SIP Session Timers and call timers: session_timer module
+
+Roadmap
+-------
+x header filter (whitelist or blacklist)
+x message filter (whitelist or blacklist)
+- SDP filter (reconstructed SDP)
+x remote URI update (host / user / host/user)
+x From update (displayname / host / host/user)
+x To update (displayname / host / host/user)
+x SIP authentication
+x session timers
+- maximum call duration timer
+- accounting (MySQL DB, cassandra DB)
+- RTP forwarding mode (bridging)
+- RTP transcoding mode (bridging)
+- overload handling (parallel call to target thresholds)
+- call distribution
+- select profile on monitoring in-mem DB record
+- fallback profile
+- add headers
+- bridging between interfaces
--- a/doc/Readme.sst_b2b.txt
+++ b/doc/Readme.sst_b2b.txt
@ -1,5 +1,12 @@
 SIP Session Timers (SST) enabled B2B application.

+-------------------------------------------------
+This application has been obsoleted by the sbc
+module and will be discontinued in the next version.
+Please use the sbc module with the sst_b2b call
+profile for the same functionality.
+-------------------------------------------------
+
 This application can be routed through for achieving 
 two things: 

@ -17,15 +24,13 @@ The incoming INVITE for a newly established call is
 passed in signaling only B2B mode to the B leg, 
 which tries to send it to the request URI.

-SIP Session Timers are enabled on both legs. When the 
-timer expires, an empty INVITE is sent, and the resulting 
-SDP offer from body of the 200 is relayed into the other 
-leg, where it is sent out as INVITE with the offer. The 
-answer from B leg is relayed into A leg and sent as body
-in ACK message.
+SIP Session Timers are enabled on both legs. The
+session refresh method may be configured; UPDATE
+or INVITE with last established SDP may be used.

 SST expiration is configurable in config file.

+Session refresh with last established SDP:

 A                  b2b                  B
 |---INVITE / SDPa-->|                   |
@ -39,9 +44,11 @@ SST expiration is configurable in config file.

          ... SST timer expires :
 |                   |                   |
- |<-- INVITE --------|                   |
- |- OK/SDPc (offer)->|                   |
- |                   |---INVITE / SDPc-->|
- |                   |<-- OK/SDPd (answ)-|
- |<----ACK/SDPd------|----ACK----------->|
+ |<-- INVITE / SDPb -|                   |
+ |- OK/SDPa (offer)->|                   |
+ |<----ACK  ---------|                   |
+ |                   |                   |
+ |                   |---INVITE / SDPa-->|
+ |                   |<-- OK/SDPb (answ)-|
+ |                   |----ACK----------->|