Use SO_REUSEADDR before calling bind() where missing. Fixes #1289.

gns3server/compute/base_node.py

@@ -514,7 +514,7 @@ class BaseNode:
         try:
             yield from self._ubridge_hypervisor.send(command)
         except UbridgeError as e:
-            raise UbridgeError("{}: {}".format(e, self._ubridge_hypervisor.read_stdout()))
+            raise UbridgeError("Error while sending command '{}': {}: {}".format(command, e, self._ubridge_hypervisor.read_stdout()))
 
     @locked_coroutine
     def _start_ubridge(self):

gns3server/compute/qemu/qemu_vm.py

@@ -894,6 +894,7 @@ class QemuVM(BaseNode):
                         af, socktype, proto, _, sa = res
                         # let the OS find an unused port for the Qemu monitor
                         with socket.socket(af, socktype, proto) as sock:
+                            sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
                             sock.bind(sa)
                             self._monitor = sock.getsockname()[1]
                 except OSError as e:

gns3server/controller/gns3vm/virtualbox_gns3_vm.py

@@ -191,6 +191,7 @@ class VirtualBoxGNS3VM(BaseGNS3VM):
         try:
             # get a random port on localhost
             with socket.socket() as s:
+                s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
                 s.bind((ip_address, 0))
                 api_port = s.getsockname()[1]
         except OSError as e:

gns3server/ubridge/hypervisor.py

@@ -62,6 +62,7 @@ class Hypervisor(UBridgeHypervisor):
                     af, socktype, proto, _, sa = res
                     # let the OS find an unused port for the uBridge hypervisor
                     with socket.socket(af, socktype, proto) as sock:
+                        sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
                         sock.bind(sa)
                         port = sock.getsockname()[1]
                         break