Fixed error in HTTPServer when AI_ADDRCONFIG is not available (as on …

…WinXP)

Closes tornadoweb#287

tornado/httpserver.py

@@ -183,8 +183,15 @@ def bind(self, port, address=None, family=socket.AF_UNSPEC):
         """
         if address == "":
             address = None
+        flags = socket.AI_PASSIVE
+        if hasattr(socket, "AI_ADDRCONFIG"):
+            # AI_ADDRCONFIG ensures that we only try to bind on ipv6
+            # if the system is configured for it, but the flag doesn't
+            # exist on some platforms (specifically WinXP, although
+            # newer versions of windows have it)
+            flags |= socket.AI_ADDRCONFIG
         for res in socket.getaddrinfo(address, port, family, socket.SOCK_STREAM,
-                                      0, socket.AI_PASSIVE | socket.AI_ADDRCONFIG):
+                                      0, flags):
             af, socktype, proto, canonname, sockaddr = res
             sock = socket.socket(af, socktype, proto)
             flags = fcntl.fcntl(sock.fileno(), fcntl.F_GETFD)

website/sphinx/releases.rst

@@ -4,6 +4,7 @@ Release notes
 .. toctree::
    :maxdepth: 2
 
+   releases/next
    releases/v2.0.0
    releases/v1.2.1
    releases/v1.2.0

website/sphinx/releases/next.rst

@@ -0,0 +1,11 @@
+What's new in the next release of Tornado
+=========================================
+
+In progress
+-----------
+
+Bug fixes
+~~~~~~~~~
+
+* `HTTPServer`: fixed exception at startup when ``socket.AI_ADDRCONFIG`` is
+  not available, as on Windows XP