MT#55831 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.
(real ticket number: TT#138356)

Change-Id: I152747271bb5d0a6838f721493fd2660a35e10f8

core/AmConfig.cpp

@@ -125,6 +125,8 @@ bool         AmConfig::AcceptForkedDialogs     = true;
 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";
   

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();

core/AmSessionContainer.cpp

@@ -444,13 +444,25 @@ unsigned int AmSessionContainer::getMaxCPS()
   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_cps()
     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::createSession(const AmSipRequest& req,
       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::createSession(const AmSipRequest& req,
       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) {

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 AmThread
   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();