1 files changed, 43 insertions, 20 deletions
diff --git a/Lib/test/test_support.py b/Lib/test/test_support.py
index ce2b679..32ff970 100644
--- a/Lib/test/test_support.py
+++ b/Lib/test/test_support.py
@@ -750,32 +750,55 @@ class TransientResource(object):
                 raise ResourceDenied("an optional resource is not available")
 
 
-_transients = {
-    IOError: (errno.ECONNRESET, errno.ETIMEDOUT),
-    socket.error: (errno.ECONNRESET,),
-    socket.gaierror: [getattr(socket, t)
-                      for t in ('EAI_NODATA', 'EAI_NONAME')
-                      if hasattr(socket, t)],
-    }
 @contextlib.contextmanager
-def transient_internet():
+def transient_internet(resource_name, timeout=30.0, errnos=()):
     """Return a context manager that raises ResourceDenied when various issues
-    with the Internet connection manifest themselves as exceptions.
+    with the Internet connection manifest themselves as exceptions."""
+    default_errnos = [
+        ('ECONNREFUSED', 111),
+        ('ECONNRESET', 104),
+        ('ENETUNREACH', 101),
+        ('ETIMEDOUT', 110),
+    ]
+
+    denied = ResourceDenied("Resource '%s' is not available" % resource_name)
+    captured_errnos = errnos
+    if not captured_errnos:
+        captured_errnos = [getattr(errno, name, num)
+                           for (name, num) in default_errnos]
+
+    def filter_error(err):
+        if (isinstance(err, socket.timeout) or
+            getattr(err, 'errno', None) in captured_errnos):
+            if not verbose:
+                sys.stderr.write(denied.args[0] + "\n")
+            raise denied
 
-    Errors caught:
-        timeout             IOError                  errno = ETIMEDOUT
-        socket reset        socket.error, IOError    errno = ECONNRESET
-        dns no data         socket.gaierror          errno = EAI_NODATA
-        dns no name         socket.gaierror          errno = EAI_NONAME
-    """
+    old_timeout = socket.getdefaulttimeout()
     try:
+        if timeout is not None:
+            socket.setdefaulttimeout(timeout)
         yield
-    except tuple(_transients) as err:
-        for errtype in _transients:
-            if isinstance(err, errtype) and err.errno in _transients[errtype]:
-                raise ResourceDenied("could not establish network "
-                                     "connection ({})".format(err))
+    except IOError as err:
+        # urllib can wrap original socket errors multiple times (!), we must
+        # unwrap to get at the original error.
+        while True:
+            a = err.args
+            if len(a) >= 1 and isinstance(a[0], IOError):
+                err = a[0]
+            # The error can also be wrapped as args[1]:
+            #    except socket.error as msg:
+            #        raise IOError('socket error', msg).with_traceback(sys.exc_info()[2])
+            elif len(a) >= 2 and isinstance(a[1], IOError):
+                err = a[1]
+            else:
+                break
+        filter_error(err)
         raise
+    # XXX should we catch generic exceptions and look for their
+    # __cause__ or __context__?
+    finally:
+        socket.setdefaulttimeout(old_timeout)
 
 
 @contextlib.contextmanager