Improve address and connection handling

* improve address checking
+ add ipv6 capabilities

Change-Id: I5369336bec449c27d79d857018f319266dfd4d0e
Reviewed-on: https://forge.frm2.tum.de/review/c/secop/frappy/+/30885
Tested-by: Jenkins Automated Tests <pedersen+jenkins@frm2.tum.de>
Reviewed-by: Alexander Zaft <a.zaft@fz-juelich.de>

frappy/protocol/interface/tcp.py

@@ -21,22 +21,22 @@
 # *****************************************************************************
 """provides tcp interface to the SECoP Server"""
 
+import errno
+import os
 import socket
 import socketserver
 import sys
 import threading
 import time
-import errno
-import os
 
 from frappy.datatypes import BoolType, StringType
 from frappy.errors import SECoPError
-from frappy.lib import formatException, \
-    formatExtendedStack, formatExtendedTraceback
+from frappy.lib import formatException, formatExtendedStack, \
+    formatExtendedTraceback
 from frappy.properties import Property
 from frappy.protocol.interface import decode_msg, encode_msg_frame, get_msg
-from frappy.protocol.messages import ERRORPREFIX, \
-    HELPREPLY, HELPREQUEST, HelpMessage
+from frappy.protocol.messages import ERRORPREFIX, HELPREPLY, HELPREQUEST, \
+    HelpMessage
 
 DEF_PORT = 10767
 MESSAGE_READ_SIZE = 1024
@@ -57,7 +57,7 @@ class TCPRequestHandler(socketserver.BaseRequestHandler):
         clientaddr = self.client_address
         serverobj = self.server
 
-        self.log.info("handling new connection from %s:%d" % clientaddr)
+        self.log.info("handling new connection from %s",  format_address(clientaddr))
         data = b''
 
         # notify dispatcher of us
@@ -160,7 +160,7 @@ class TCPRequestHandler(socketserver.BaseRequestHandler):
 
     def finish(self):
         """called when handle() terminates, i.e. the socket closed"""
-        self.log.info('closing connection from %s:%d' % self.client_address)
+        self.log.info('closing connection from %s', format_address(self.client_address))
         # notify dispatcher
         self.server.dispatcher.remove_connection(self)
         # close socket
@@ -171,8 +171,28 @@ class TCPRequestHandler(socketserver.BaseRequestHandler):
         finally:
             self.request.close()
 
+class DualStackTCPServer(socketserver.ThreadingTCPServer):
+    """Subclassed to provide IPv6 capabilities as socketserver only uses IPv4"""
+    def __init__(self, server_address, RequestHandlerClass, bind_and_activate=True, enable_ipv6=False):
+        super().__init__(
+                    server_address, RequestHandlerClass, bind_and_activate=False)
 
-class TCPServer(socketserver.ThreadingTCPServer):
+        # override default socket
+        if enable_ipv6:
+            self.address_family = socket.AF_INET6
+            self.socket = socket.socket(self.address_family,
+                                        self.socket_type)
+            self.socket.setsockopt(socket.IPPROTO_IPV6, socket.IPV6_V6ONLY, 0)
+        if bind_and_activate:
+            try:
+                self.server_bind()
+                self.server_activate()
+            except:
+                self.server_close()
+                raise
+
+
+class TCPServer(DualStackTCPServer):
     daemon_threads = True
     # on windows, 'reuse_address' means that several servers might listen on
     # the same port, on the other hand, a port is not blocked after closing
@@ -191,13 +211,16 @@ class TCPServer(socketserver.ThreadingTCPServer):
         self.name = name
         self.log = logger
         port = int(options.pop('uri').split('://', 1)[-1])
+        enable_ipv6 = options.pop('ipv6', False)
         self.detailed_errors = options.pop('detailed_errors', False)
 
         self.log.info("TCPServer %s binding to port %d", name, port)
         for ntry in range(5):
             try:
-                socketserver.ThreadingTCPServer.__init__(
-                    self, ('0.0.0.0', port), TCPRequestHandler, bind_and_activate=True)
+                DualStackTCPServer.__init__(
+                    self, ('', port), TCPRequestHandler,
+                    bind_and_activate=True, enable_ipv6=enable_ipv6
+                )
                 break
             except OSError as e:
                 if e.args[0] == errno.EADDRINUSE:  # address already in use
@@ -217,3 +240,11 @@ class TCPServer(socketserver.ThreadingTCPServer):
 
         def __exit__(self, *args):
             self.server_close()
+
+def format_address(addr):
+    if len(addr) == 2:
+        return '%s:%d' % addr
+    address, port = addr[0:2]
+    if address.startswith('::ffff'):
+        return '%s:%d' % (address[7:], port)
+    return '[%s]:%d' % (address, port)