Unable to call socket.gethostbyname() when disconnected

A Gentoo ticket notes an interesting stacktrace...

  https://bugs.gentoo.org/show_bug.cgi?id=527072

  ======================================================================
  ERROR: test_all_private_policy
  ----------------------------------------------------------------------
  Traceback (most recent call last):
    File "/tmp/portage/net-libs/stem-1.2.2_p20141018/work/stem-1.2.2_p20141018/test/unit/exit_policy/policy.py", line 115, in test_all_private_policy
      private_policy = get_config_policy('reject private:%s' % port)
    File "/tmp/portage/net-libs/stem-1.2.2_p20141018/work/stem-1.2.2_p20141018/stem/exit_policy.py", line 141, in get_config_policy
      ip_address = socket.gethostbyname(socket.gethostname())
  gaierror: [Errno -3] Temporary failure in name resolution
  ======================================================================

I wasn't able to repro this by simply disconnecting, but oh well. Easy enough
to suppress the exception.

1 files changed, 9 insertions, 3 deletions

diff --git a/stem/exit_policy.py b/stem/exit_policy.py
index 0b7bea7c..9bc8ccb9 100644
--- a/stem/exit_policy.py
+++ b/stem/exit_policy.py
@@ -136,11 +136,17 @@ def get_config_policy(rules, ip_address = None):
     if 'private' in rule:
       acceptance = rule.split(' ', 1)[0]
       port = rule.split(':', 1)[1]
+      addresses = list(PRIVATE_ADDRESSES)
 
-      if ip_address is None:
-        ip_address = socket.gethostbyname(socket.gethostname())
+      if ip_address:
+        addresses.append(ip_address)
+      else:
+        try:
+          addresses.append(socket.gethostbyname(socket.gethostname()))
+        except:
+          pass  # we might not have a network connection
 
-      for private_addr in PRIVATE_ADDRESSES + (ip_address,):
+      for private_addr in addresses:
         result.append(ExitPolicyRule("%s %s:%s" % (acceptance, private_addr, port)))
     else:
       result.append(ExitPolicyRule(rule))