PYTHON-2795 Improve host parsing and error messages

pymongo/_ipaddress.py

@@ -0,0 +1,56 @@
+# Copyright 2021-present MongoDB, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Test if a string is an IP Address"""
+
+import socket
+
+from bson.py3compat import _unicode
+
+try:
+    from ipaddress import ip_address
+    def is_ip_address(address):
+        try:
+            ip_address(_unicode(address))
+            return True
+        except (ValueError, UnicodeError):
+            return False
+except ImportError:
+    if hasattr(socket, 'inet_pton') and socket.has_ipv6:
+        # Most *nix, Windows newer than XP
+        def is_ip_address(address):
+            try:
+                # inet_pton rejects IPv4 literals with leading zeros
+                # (e.g. 192.168.0.01), inet_aton does not, and we
+                # can connect to them without issue. Use inet_aton.
+                socket.inet_aton(address)
+                return True
+            except socket.error:
+                try:
+                    socket.inet_pton(socket.AF_INET6, address)
+                    return True
+                except socket.error:
+                    return False
+    else:
+        # No inet_pton
+        def is_ip_address(address):
+            try:
+                socket.inet_aton(address)
+                return True
+            except socket.error:
+                if ':' in address:
+                    # ':' is not a valid character for a hostname.
+                    return True
+                return False
+

pymongo/mongo_client.py

@@ -658,7 +658,10 @@ class MongoClient(common.BaseObject):
         opts = common._CaseInsensitiveDictionary()
         fqdn = None
         for entity in host:
-            if "://" in entity:
+            # A hostname can only include a-z, 0-9, '-' and '.'. If we find a '/'
+            # it must be a URI,
+            # https://en.wikipedia.org/wiki/Hostname#Restrictions_on_valid_host_names
+            if "/" in entity:
                 # Determine connection timeout from kwargs.
                 timeout = keyword_opts.get("connecttimeoutms")
                 if timeout is not None:

pymongo/pool.py

@@ -52,6 +52,7 @@ from pymongo.errors import (AutoReconnect,
                             OperationFailure,
                             PyMongoError)
 from pymongo.hello import HelloCompat
+from pymongo._ipaddress import is_ip_address
 from pymongo.ismaster import IsMaster
 from pymongo.monotonic import time as _time
 from pymongo.monitoring import (ConnectionCheckOutFailedReason,
@@ -65,51 +66,6 @@ from pymongo.socket_checker import SocketChecker
 # Always use our backport so we always have support for IP address matching
 from pymongo.ssl_match_hostname import match_hostname
 
-# For SNI support. According to RFC6066, section 3, IPv4 and IPv6 literals are
-# not permitted for SNI hostname.
-try:
-    from ipaddress import ip_address
-    def is_ip_address(address):
-        try:
-            ip_address(_unicode(address))
-            return True
-        except (ValueError, UnicodeError):
-            return False
-except ImportError:
-    if hasattr(socket, 'inet_pton') and socket.has_ipv6:
-        # Most *nix, recent Windows
-        def is_ip_address(address):
-            try:
-                # inet_pton rejects IPv4 literals with leading zeros
-                # (e.g. 192.168.0.01), inet_aton does not, and we
-                # can connect to them without issue. Use inet_aton.
-                socket.inet_aton(address)
-                return True
-            except socket.error:
-                try:
-                    socket.inet_pton(socket.AF_INET6, address)
-                    return True
-                except socket.error:
-                    return False
-    else:
-        # No inet_pton
-        def is_ip_address(address):
-            try:
-                socket.inet_aton(address)
-                return True
-            except socket.error:
-                if ':' in address:
-                    # ':' is not a valid character for a hostname. If we get
-                    # here a few things have to be true:
-                    #   - We're on a recent version of python 2.7 (2.7.9+).
-                    #     Older 2.7 versions don't support SNI.
-                    #   - We're on Windows XP or some unusual Unix that doesn't
-                    #     have inet_pton.
-                    #   - The application is using IPv6 literals with TLS, which
-                    #     is pretty unusual.
-                    return True
-                return False
-
 try:
     from fcntl import fcntl, F_GETFD, F_SETFD, FD_CLOEXEC
     def _set_non_inheritable_non_atomic(fd):

pymongo/srv_resolver.py

@@ -24,6 +24,7 @@ from bson.py3compat import PY3
 
 from pymongo.common import CONNECT_TIMEOUT
 from pymongo.errors import ConfigurationError
+from pymongo._ipaddress import is_ip_address
 
 
 if PY3:
@@ -46,6 +47,9 @@ def _resolve(*args, **kwargs):
     # dnspython 1.X
     return resolver.query(*args, **kwargs)
 
+_INVALID_HOST_MSG = (
+    "Invalid URI host: %s is not a valid hostname for 'mongodb+srv://'. "
+    "Did you mean to use 'mongodb://'?")
 
 class _SrvResolver(object):
     def __init__(self, fqdn, connect_timeout=None):
@@ -53,13 +57,16 @@ class _SrvResolver(object):
         self.__connect_timeout = connect_timeout or CONNECT_TIMEOUT
 
         # Validate the fully qualified domain name.
+        if is_ip_address(fqdn):
+            raise ConfigurationError(_INVALID_HOST_MSG % ("an IP address",))
+
         try:
             self.__plist = self.__fqdn.split(".")[1:]
         except Exception:
-            raise ConfigurationError("Invalid URI host: %s" % (fqdn,))
+            raise ConfigurationError(_INVALID_HOST_MSG % (fqdn,))
         self.__slen = len(self.__plist)
         if self.__slen < 2:
-            raise ConfigurationError("Invalid URI host: %s" % (fqdn,))
+            raise ConfigurationError(_INVALID_HOST_MSG % (fqdn,))
 
     def get_options(self):
         try:

test/test_client.py

@@ -169,6 +169,20 @@ class ClientUnitTest(unittest.TestCase):
         with self.assertRaises(ValueError):
             MongoClient(maxPoolSize=0)
 
+    def test_uri_detection(self):
+        self.assertRaises(
+            ConfigurationError,
+            MongoClient,
+            "/foo")
+        self.assertRaises(
+            ConfigurationError,
+            MongoClient,
+            "://")
+        self.assertRaises(
+            ConfigurationError,
+            MongoClient,
+            "foo/")
+
     def test_get_db(self):
         def make_db(base, name):
             return base[name]

test/test_dns.py

@@ -142,12 +142,20 @@ class TestParsingErrors(unittest.TestCase):
     def test_invalid_host(self):
         self.assertRaisesRegex(
             ConfigurationError,
-            "Invalid URI host: mongodb",
+            "Invalid URI host: mongodb is not",
             MongoClient, "mongodb+srv://mongodb")
         self.assertRaisesRegex(
             ConfigurationError,
-            "Invalid URI host: mongodb.com",
+            "Invalid URI host: mongodb.com is not",
             MongoClient, "mongodb+srv://mongodb.com")
+        self.assertRaisesRegex(
+            ConfigurationError,
+            "Invalid URI host: an IP address is not",
+            MongoClient, "mongodb+srv://127.0.0.1")
+        self.assertRaisesRegex(
+            ConfigurationError,
+            "Invalid URI host: an IP address is not",
+            MongoClient, "mongodb+srv://[::1]")
 
 
 if __name__ == '__main__':