More graceful handling of disabled listeners

Don't assume a lack of TCP listeners means the server will be
unreachable. There might be other methods of access, so let the higher
levels do that sanity check instead.

common/network/TcpSocket.cxx

@@ -496,10 +496,6 @@ void network::createTcpListeners(std::list<SocketListener*> *listeners,
     }
   }
 
-  if (new_listeners.empty ())
-    throw SocketException("createTcpListeners: no addresses available",
-                          EADDRNOTAVAIL);
-
   listeners->splice (listeners->end(), new_listeners);
 }
 

unix/x0vncserver/x0vncserver.cxx

@@ -306,16 +306,22 @@ int main(int argc, char** argv)
     }
 
     if ((int)rfbport != -1) {
+      std::list<network::SocketListener*> tcp_listeners;
       const char *addr = interface;
+
       if (strcasecmp(addr, "all") == 0)
         addr = 0;
       if (localhostOnly)
-        createLocalTcpListeners(&listeners, (int)rfbport);
+        createLocalTcpListeners(&tcp_listeners, (int)rfbport);
       else
-        createTcpListeners(&listeners, addr, (int)rfbport);
-      vlog.info("Listening for VNC connections on %s interface(s), port %d",
-                localhostOnly ? "local" : (const char*)interface,
-                (int)rfbport);
+        createTcpListeners(&tcp_listeners, addr, (int)rfbport);
+
+      if (!tcp_listeners.empty()) {
+        listeners.splice (listeners.end(), tcp_listeners);
+        vlog.info("Listening for VNC connections on %s interface(s), port %d",
+                  localhostOnly ? "local" : (const char*)interface,
+                  (int)rfbport);
+      }
 
       FileTcpFilter fileTcpFilter(hostsFile);
       if (strlen(hostsFile) != 0)
@@ -325,6 +331,11 @@ int main(int argc, char** argv)
           (*i)->setFilter(&fileTcpFilter);
     }
 
+    if (listeners.empty()) {
+      vlog.error("No path or port configured for incoming connections");
+      return -1;
+    }
+
     PollingScheduler sched((int)pollingCycle, (int)maxProcessorUsage);
 
     while (!caughtSignal) {

unix/xserver/hw/vnc/vncExtInit.cc

@@ -229,22 +229,29 @@ void vncExtensionInit(void)
         }
 
         if (!inetd && rfbport != -1) {
+          std::list<network::SocketListener*> tcp_listeners;
           const char *addr = interface;
           int port = rfbport;
           if (port == 0) port = 5900 + atoi(vncGetDisplay());
           port += 1000 * scr;
           if (strcasecmp(addr, "all") == 0)
             addr = 0;
           if (localhostOnly)
-            network::createLocalTcpListeners(&listeners, port);
+            network::createLocalTcpListeners(&tcp_listeners, port);
           else
-            network::createTcpListeners(&listeners, addr, port);
+            network::createTcpListeners(&tcp_listeners, addr, port);
 
-          vlog.info("Listening for VNC connections on %s interface(s), port %d",
-                    localhostOnly ? "local" : (const char*)interface,
-                    port);
+          if (!tcp_listeners.empty()) {
+            listeners.splice (listeners.end(), tcp_listeners);
+            vlog.info("Listening for VNC connections on %s interface(s), port %d",
+                      localhostOnly ? "local" : (const char*)interface,
+                      port);
+          }
         }
 
+        if (!inetd && listeners.empty())
+          throw rdr::Exception("No path or port configured for incoming connections");
+
         PixelFormat pf = vncGetPixelFormat(scr);
 
         vncSetGlueContext(scr);

vncviewer/vncviewer.cxx

@@ -756,6 +756,8 @@ int main(int argc, char** argv)
         port = atoi(vncServerName);
 
       createTcpListeners(&listeners, 0, port);
+      if (listeners.empty())
+        throw Exception(_("Unable to listen for incoming connections"));
 
       vlog.info(_("Listening on port %d"), port);