[config, daemon] catch TSTP, CONT is option

daemon/UnixDaemon.cpp

@@ -60,7 +60,7 @@ void handle_signal(int sig)
             i2p::transport::transports.SetOnline(false);
             break;
         case SIGCONT:
-            LogPrint(eLogInfo, "Daemon: Got SIGCONT, restore connection to network...");
+            LogPrint(eLogInfo, "Daemon: Got SIGCONT, restoring connection to network...");
             i2p::transport::transports.SetOnline(true);
             break;
         }
@@ -180,6 +180,9 @@ namespace i2p
 			}
 			gracefulShutdownInterval = 0; // not specified
 
+            // handle signal TSTP
+            bool handleTSTP; i2p::config::GetOption("unix.handle_sigtstp", handleTSTP);
+
             // Signal handler
             struct sigaction sa;
             sa.sa_handler = handle_signal;
@@ -191,6 +194,11 @@ namespace i2p
             sigaction(SIGTERM, &sa, 0);
             sigaction(SIGINT, &sa, 0);
             sigaction(SIGPIPE, &sa, 0);
+            if (handleTSTP)
+            {
+                sigaction(SIGTSTP, &sa, 0);
+                sigaction(SIGCONT, &sa, 0);
+            }
 
             return Daemon_Singleton::start();
 		}

libi2pd/Config.cpp

@@ -311,6 +311,19 @@ namespace config {
 			("meshnets.yggaddress", value<std::string>()->default_value(""),         "Yggdrasil address to publish")
 		;
 
+#ifdef __linux__
+        options_description unix_specific("UNIX-specific options");
+        unix_specific.add_options()
+            ("unix.handle_sigtstp", bool_switch()->default_value(false),
+                    "Switch to offline mode if received signal TSTP (SIGTSTP)"
+                    "(you   can send it by pressing CTRL+Z in terminal or with"
+                    " help commapnd kill and others, a.e pkill, if i2pd in "
+                    "daemon mode). If you need to switch to online mode, send"
+                    " signal CONT (SIGCONT)")
+        ;
+#endif
+
+
 		m_OptionsDesc
 			.add(general)
 			.add(limits)
@@ -334,6 +347,9 @@ namespace config {
 			.add(persist)
 			.add(cpuext)
 			.add(meshnets)
+#ifdef __linux__
+            .add(unix_specific)
+#endif
 		;
 	}