TT#138356 Detect emergency calls and let them pass on license limitation (SEMS CE)

Remark: this commit is created as an attempt to keep PRO / CE sems repositories
consistent in terms of the provided code and functionality.

We need to have a possibility to detect emergency calls and let them
pass through the SEMS, even if the license limitation (CPSLimit) is triggered.

Also taking into account the global policy defined by the cfg parameter
'skip_cpslimit_emergency'.
If set to 'yes' (in the code will be treated as True)
then we do not drop emergency calls on CPSLimit triggering.
If set to 'no' - we treat emergency calls
as if they were usual calls in terms of checking CPSLimit license limitation.

Change-Id: I4ab1d2d0b7286b05e1fc2cf2a432fdfd220ca72f

debian/patches/series

@@ -40,3 +40,4 @@ sipwise/port_to_py3k.patch
 sipwise/db_reg_agent_auth_header.patch
 sipwise/skip_outbound_auth_if_credentials_empty.patch
 sipwise/add_support_for_peering_outbound_registration.patch
+sipwise/cpslimit_detect_emergency_calls_and_let_them_pass.patch

debian/patches/sipwise/cpslimit_detect_emergency_calls_and_let_them_pass.patch

@@ -0,0 +1,126 @@
+--- a/core/AmConfig.cpp
++++ b/core/AmConfig.cpp
+@@ -125,6 +125,8 @@ bool         AmConfig::AcceptForkedDialo
+ bool         AmConfig::ShutdownMode            = false;
+ unsigned int AmConfig::ShutdownModeErrCode     = 503;
+ string       AmConfig::ShutdownModeErrReason   = "Server shutting down";
++
++bool         AmConfig::skip_cpslimit_emergency = true;
+   
+ string AmConfig::OptionsTranscoderOutStatsHdr; // empty by default
+ string AmConfig::OptionsTranscoderInStatsHdr; // empty by default
+@@ -458,6 +460,11 @@ int AmConfig::readConfiguration()
+       }
+   }
+ 
++  // skip_cpslimit_emergency = true - do not drop emergency calls on CPSLimit
++  // skip_cpslimit_emergency = false - drop emergency calls on CPSLimit
++  if (cfg.hasParameter("skip_cpslimit_emergency"))
++    skip_cpslimit_emergency = cfg.getParameter("skip_cpslimit_emergency")=="yes";
++
+   if(cfg.hasParameter("log_sessions"))
+     LogSessions = cfg.getParameter("log_sessions")=="yes";
+   
+--- a/core/AmConfig.h
++++ b/core/AmConfig.h
+@@ -281,6 +281,9 @@ struct AmConfig
+ 
+   static AmAudio::ResamplingImplementationType ResamplingImplementationType;
+ 
++  /* Global policy for treating emergency calls on CPSLimit triggering */
++  static bool skip_cpslimit_emergency;
++
+   /** Read global configuration file and insert values. Maybe overwritten by
+    * command line arguments */
+   static int readConfiguration();
+--- a/core/AmSessionContainer.cpp
++++ b/core/AmSessionContainer.cpp
+@@ -444,13 +444,25 @@ unsigned int AmSessionContainer::getMaxC
+   return res;
+ }
+ 
+-bool AmSessionContainer::check_and_add_cps()
++// we need the emergency_flag to mark emergency calls
++// and skip checking CPSLimit for them if the global policy is so
++// emergency_flag = True - do not run CPSLimit check for the call
++// emergency_flag = False - run CPSLimit check for the call
++bool AmSessionContainer::check_and_add_cps(bool emergency_flag)
+ {
+   struct timeval tv, res;
+   gettimeofday(&tv,0);
+ 
+   AmLock lock(cps_mut);
+ 
++  // check global policy for dropping emergency calls
++  if (!AmConfig::skip_cpslimit_emergency && emergency_flag) {
++    emergency_flag = AmConfig::skip_cpslimit_emergency;
++    DBG("Emergency call detected, but global policy is to do the CPSLimit check (license).\n");
++  }
++
++  if (emergency_flag) DBG("Emergency call detected, skip CPSLimit check (license).\n");
++
+   while (cps_queue.size()) {
+     timersub(&tv, &cps_queue.front(), &res);
+     if (res.tv_sec >= CPS_SAMPLERATE) {
+@@ -466,7 +478,7 @@ bool AmSessionContainer::check_and_add_c
+     max_cps = cps;
+   }
+ 
+-  if( CPSLimit && cps > CPSLimit ){
++  if( CPSLimit && cps > CPSLimit && !emergency_flag){
+     DBG("cps_limit %d reached. Not creating session.\n", CPSLimit);
+     return true;
+   }
+@@ -500,7 +512,20 @@ AmSession* AmSessionContainer::createSes
+       return NULL;
+   }
+ 
+-  if (check_and_add_cps()) {
++  map<string,string> app_params;
++  parse_app_params(req.hdrs,app_params);
++
++  // look into P-App-Param list, try to find 'emergency' marker
++  emergency_flag = false;
++  map<string, string>::iterator it;
++
++  it = app_params.find(EMERGENCY_PARAM);
++  if (it != app_params.end() && (it->first == EMERGENCY_PARAM && it->second == "1")) {
++    DBG("Emergency parameter detected: <;%s=%s> .\n", it->first.c_str(), it->second.c_str());
++    emergency_flag = true;
++  }
++
++  if (check_and_add_cps(emergency_flag)) {
+       AmSipDialog::reply_error(req,AmConfig::CPSLimitErrCode, 
+ 			       AmConfig::CPSLimitErrReason);
+       return NULL;
+@@ -520,9 +545,6 @@ AmSession* AmSessionContainer::createSes
+       return NULL;
+   }
+ 
+-  map<string,string> app_params;
+-  parse_app_params(req.hdrs,app_params);
+-
+   AmSession* session = NULL;
+   if (req.method == "INVITE") {
+     if (NULL != session_params) {
+--- a/core/AmSessionContainer.h
++++ b/core/AmSessionContainer.h
+@@ -37,6 +37,8 @@
+ #include <queue>
+ #include <map>
+ 
++#define EMERGENCY_PARAM "emergency"
++
+ using std::string;
+ 
+ /**
+@@ -96,7 +98,8 @@ class AmSessionContainer : public AmThre
+   unsigned int CPSLimit;
+   unsigned int CPSHardLimit;
+ 
+-  bool check_and_add_cps();
++  bool check_and_add_cps(bool emergency_flag);
++  bool emergency_flag;
+ 
+  public:
+   static AmSessionContainer* instance();