caucase.test: get IP address from CAUCASE_LOC instead of hardcode IP

caucase/test.py

@@ -3439,7 +3439,18 @@ class CaucaseTest(TestCase):
     """
     Test that it is possible to use a literal IPv4 as netloc.
     """
-    self._testHttpCustomNetLoc(netloc='127.0.0.1')
+    parsed_url = urllib_parse.urlparse(self._caucase_url)
+    try:
+      # pylint: disable=unused-variable
+      family, socktype, proto, canonname, (address, port) = socket.getaddrinfo(
+        parsed_url.hostname, None, socket.AF_INET, socket.SOCK_STREAM,
+      )[0] # Any is fine, pick the first one
+      # pylint: enable=unused-variable
+    except socket.gaierror: # pragma: no cover
+      raise unittest.SkipTest(
+        "Cannot resolve %r as AF_INET" % (parsed_url.hostname, )
+      )
+    self._testHttpCustomNetLoc(netloc=address)
 
   def testHttpNetlocIPv6(self):
     """
@@ -3447,7 +3458,18 @@ class CaucaseTest(TestCase):
     This used to fail because cryptography module would reject bare IPv6
     address in CRL distribution point extension (unlike IPv4).
     """
-    self._testHttpCustomNetLoc(netloc='[::1]')
+    parsed_url = urllib_parse.urlparse(self._caucase_url)
+    try:
+      # pylint: disable=unused-variable
+      family, socktype, proto, canonname, (address, port, flowinfo, scope_id) = socket.getaddrinfo(
+        parsed_url.hostname, None, socket.AF_INET6, socket.SOCK_STREAM,
+      )[0] # Any is fine, pick the first one
+      # pylint: enable=unused-variable
+    except socket.gaierror: # pragma: no cover
+      raise unittest.SkipTest(
+        "Cannot resolve %r as AF_INET6" % (parsed_url.hostname, )
+      )
+    self._testHttpCustomNetLoc(netloc='[' + address + ']')
 
   def testServerFilePermissions(self):
     """