zstor_2zurl: Fix ipv6 host for NEO/ZEO + test fix

This patch allows using WCFS with a NEO or ZEO storage which is
reachable by a URL which contains an ipv6 host.

Without this patch the following example doesn't work:

>>> from wendelin.lib.zodb import dbopen
>>> root = dbopen("neo://cluster-name@[::1]:2051")
>>> # "abc" points to a ZBigArray
>>> root["abc"][0]

It doesn't work because the parser missed adding square brackets around
ipv6 hosts, due to which unparsing the resulting URL resulted in a wrong
interpretation where a port starts.

This patch furthermore amends 'test_zstor_2zurl' to test ZEO and NEO
storages with ipv6 hosts.

---

/reviewed-by @kirr
/reviewed-on !13

lib/tests/test_zodb.py

@@ -519,8 +519,12 @@ def test_zstor_2zurl(tmpdir, neo_ssl_dict):
     _(zeo("test",  "/path/to/zeo.sock"),    "zeo:///path/to/zeo.sock?storage=test") #   + non-default storage name
     _(zeo("1",     ("127.0.0.1", 1234)),    "zeo://127.0.0.1:1234")                 # ZEO/ip4
     _(zeo("test",  ("127.0.0.1", 1234)),    "zeo://127.0.0.1:1234?storage=test")    #   + non-default storage name
+    _(zeo("1",     ("::1",       1234)),    "zeo://[::1]:1234")                     # ZEO/ip6
+    _(zeo("test",  ("::1",       1234)),    "zeo://[::1]:1234?storage=test")        #   + non-default storage name
     _(neo("test",  "127.0.0.1:1234"),       "neo://127.0.0.1:1234/test")            # NEO/ip4
     _(neo("test",  "127.0.0.1:1234", 1),    "neos://%s@127.0.0.1:1234/test" % sslp) #   + ssl
+    _(neo("test",  "[::1]:1234"),           "neo://[::1]:1234/test")                # NEO/ip6
+    _(neo("test",  "[::1]:1234", 1),        "neos://%s@[::1]:1234/test" % sslp)     #   + ssl
     _(demo(zeo("base", ("1.2.3.4",  5)),                                            # DemoStorage
            fs1("delta.fs")),                "demo:(zeo://1.2.3.4:5?storage=base)/(file://%s/delta.fs)" % tmpdir)
 

lib/zodb.py

 # -*- coding: utf-8 -*-
 # Wendelin.bigfile | common ZODB-related helpers
-# Copyright (C) 2014-2021  Nexedi SA and Contributors.
+# Copyright (C) 2014-2022  Nexedi SA and Contributors.
 #                          Kirill Smelkov <kirr@nexedi.com>
 #
 # This program is free software: you can Use, Study, Modify and Redistribute
@@ -31,6 +31,7 @@ import zodbtools.util
 from weakref import WeakSet
 import gc
 from six.moves.urllib import parse as urlparse
+import socket
 
 import pkg_resources
 
@@ -374,6 +375,8 @@ def zstor_2zurl(zstor):
             u += addr
         else:
             host, port = addr
+            if _is_ipv6(host):
+              host = "[%s]" % host
             u += '%s:%d' % (host, port)
 
         storage = zstor._storage
@@ -402,8 +405,11 @@ def zstor_2zurl(zstor):
             raise NotImplementedError("NEO client has multiple configured masters: %r" % (masterv,))
         master = masterv[0]
         host, port = master.getAddress()
-        u += "%s:%s" % (host, port)
 
+        if _is_ipv6(host):
+            host = "[%s]" % host
+
+        u += "%s:%s" % (host, port)
         u += "/%s" % app.name
 
         return u
@@ -416,3 +422,11 @@ def zstor_2zurl(zstor):
             "\tanother in-RAM storage in WCFS process.") % ztype)
 
     raise NotImplementedError("don't know how to extract zurl from %r" % zstor)
+
+
+def _is_ipv6(host):
+    try:
+        socket.inet_pton(socket.AF_INET6, host)
+    except socket.error:
+        return False
+    return True