Fix/redirect (#104)

* Update txextra to fix issue in redirect handling

* Ignore private redirects

* Pass the extra argument in the correct place

* Add support for loading headers from http_request_headers dictionary

* Stringify http_request_headers to make twisted happy

* Add extra argument to web_connectivity test helper call

Author: hellais

oonib/common/ip_utils.py

@@ -0,0 +1,49 @@
+from ipaddr import IPv4Address, IPv6Address
+from ipaddr import AddressValueError
+
+
+def in_private_ip_space(address):
+    ip_address = IPv4Address(address)
+    return any(
+        [ip_address.is_private, ip_address.is_loopback]
+    )
+
+def is_public_ipv4_address(address):
+    try:
+        return not in_private_ip_space(address)
+    except AddressValueError:
+        return False
+
+def is_private_ipv4_address(address):
+    try:
+        return in_private_ip_space(address)
+    except AddressValueError:
+        return False
+
+
+def is_private_address(address, only_loopback=False):
+    """
+    Checks to see if an IP address is in private IP space and if the
+    hostname is either localhost or *.local.
+
+    :param address: an IP address of a hostname
+    :param only_loopback: will only check if the IP address is either
+        127.0.0.1/8 or ::1 in ipv6
+    :return: True if the IP address or host is in private space
+    """
+    try:
+        ip_address = IPv4Address(address)
+    except AddressValueError:
+        try:
+            ip_address = IPv6Address(address)
+        except AddressValueError:
+            if address == "localhost":
+                return True
+            elif address.endswith(".local"):
+                return True
+            return False
+
+    candidates = [ip_address.is_loopback]
+    if not only_loopback:
+        candidates.append(ip_address.is_private)
+    return any(candidates)

oonib/common/txextra.py

@@ -19,6 +19,8 @@
 
 from twisted.python import log
 
+from .ip_utils import is_private_address
+
 class TrueHeaders(Headers):
     def __init__(self, rawHeaders=None):
         self._rawHeaders = dict()
@@ -35,6 +37,12 @@ def setRawHeaders(self, name, values):
         self._rawHeaders[name.lower()]['name'] = name
         self._rawHeaders[name.lower()]['values'] = values
 
+    def copy(self):
+        rawHeaders = {}
+        for k, v in self.getAllRawHeaders():
+            rawHeaders[k] = v
+        return self.__class__(rawHeaders)
+
     def getAllRawHeaders(self):
         for _, v in self._rawHeaders.iteritems():
             yield v['name'], v['values']
@@ -168,6 +176,10 @@ class FixedRedirectAgent(BrowserLikeRedirectAgent):
     This is a redirect agent with this patch manually applied:
     https://twistedmatrix.com/trac/ticket/8265
     """
+    def __init__(self, agent, redirectLimit=20, ignorePrivateRedirects=False):
+        self.ignorePrivateRedirects = ignorePrivateRedirects
+        BrowserLikeRedirectAgent.__init__(self, agent, redirectLimit)
+
     def _handleRedirect(self, response, method, uri, headers, redirectCount):
         """
         Handle a redirect response, checking the number of redirects already
@@ -191,12 +203,26 @@ def _handleRedirect(self, response, method, uri, headers, redirectCount):
             response.request.absoluteURI,
             locationHeaders[0]
         )
+        if getattr(client, 'URI', None):
+            uri = client.URI.fromBytes(location)
+        else:
+            # Backward compatibility with twisted 14.0.2
+            uri = client._URI.fromBytes(location)
+        if self.ignorePrivateRedirects and is_private_address(uri.host,
+                                                              only_loopback=True):
+            return response
+
         deferred = self._agent.request(method, location, headers)
 
         def _chainResponse(newResponse):
+            if isinstance(newResponse, Failure):
+                # This is needed to write the response even in case of failure
+                newResponse.previousResponse = response
+                newResponse.requestLocation = location
+                return newResponse
             newResponse.setPreviousResponse(response)
             return newResponse
 
-        deferred.addCallback(_chainResponse)
+        deferred.addBoth(_chainResponse)
         return deferred.addCallback(
             self._handleResponse, method, uri, headers, redirectCount + 1)

oonib/testhelpers/http_helpers.py

@@ -309,8 +309,9 @@ def lookup(self, response_type, key):
         defer.returnValue(value)
 
     @defer.inlineCallbacks
-    def http_request(self, url, include_http_responses=False):
-        cached_value = yield self.lookup('http_request', url)
+    def http_request(self, url, http_request_headers, include_http_responses=False):
+        key = url + json.dumps(http_request_headers)
+        cached_value = yield self.lookup('http_request', key)
         if cached_value is not None:
             if include_http_responses is not True:
                 cached_value.pop('responses', None)
@@ -324,15 +325,16 @@ def http_request(self, url, include_http_responses=False):
         }
 
         agent = ContentDecoderAgent(
-            FixedRedirectAgent(TrueHeadersAgent(reactor)),
-                               [('gzip', GzipDecoder)]
+            FixedRedirectAgent(TrueHeadersAgent(reactor),
+                               ignorePrivateRedirects=True),
+            [('gzip', GzipDecoder)]
         )
         try:
             retries = 0
             while True:
                 try:
                     response = yield agent.request('GET', url,
-                                                   TrueHeaders(REQUEST_HEADERS))
+                                                   TrueHeaders(http_request_headers))
                     headers = {}
                     for name, value in response.headers.getAllRawHeaders():
                         headers[name] = unicode(value[0], errors='ignore')
@@ -364,11 +366,13 @@ def http_request(self, url, include_http_responses=False):
             page_info['failure'] = 'connection_refused_error'
         except ConnectError:
             page_info['failure'] = 'connect_error'
-        except:
+        except Exception as exc:
             # XXX map more failures
             page_info['failure'] = 'unknown_error'
+            log.err("Unknown error occurred")
+            log.exception(exc)
 
-        yield self.cache_value('http_request', url, page_info)
+        yield self.cache_value('http_request', key, page_info)
         if include_http_responses is not True:
             page_info.pop('responses', None)
         defer.returnValue(page_info)
@@ -451,10 +455,14 @@ class WebConnectivity(OONIBHandler):
     @defer.inlineCallbacks
     def control_measurement(self, http_url, socket_list,
                             include_http_responses,
-                            invalid_sockets):
+                            invalid_sockets,
+                            http_request_headers=None):
+        if http_request_headers is None:
+            http_request_headers = {}
+
         hostname = urlparse(http_url).netloc
         dl = [
-            web_connectivity_cache.http_request(http_url, include_http_responses),
+            web_connectivity_cache.http_request(http_url, http_request_headers, include_http_responses),
             web_connectivity_cache.dns_consistency(hostname)
         ]
         for socket in socket_list:
@@ -477,12 +485,20 @@ def control_measurement(self, http_url, socket_list,
         })
 
     def validate_request(self, request):
+        allowed_headers = ['user-agent', 'accept', 'accept-language']
         required_keys = ['http_request', 'tcp_connect']
         for rk in required_keys:
             if rk not in request.keys():
                 raise HTTPError(400, "Missing %s" % rk)
         if not HTTP_REQUEST_REGEXP.match(request['http_request']):
             raise HTTPError(400, "Invalid http_request URL")
+
+        http_request_headers = request.get('http_request_headers', {})
+        for k, v in http_request_headers.iteritems():
+            if k.lower() not in allowed_headers:
+                raise HTTPError(400, "Invalid header %s" % k)
+            if not isinstance(v, list):
+                raise HTTPError(400, "Headers must be a list")
         # We don't need to check the tcp_connect field because we strip it in
         # the post already.
 
@@ -508,13 +524,22 @@ def post(self):
             request['tcp_connect'] = tcp_connect
 
             self.validate_request(request)
-            include_http_responses = request.get("include_http_responses",
-                                                 False)
+            include_http_responses = request.get(
+                    "include_http_responses",
+                    False
+            )
+
+            # We convert headers to str so twisted is happy (unicode triggers
+            # errors)
+            http_request_headers = {}
+            for k, v in request.get('http_request_headers', {}).iteritems():
+                http_request_headers[str(k)] = map(str, v)
             self.control_measurement(
-                str(request['http_request']),
-                request['tcp_connect'],
-                include_http_responses,
-                invalid_sockets
+                http_url=str(request['http_request']),
+                include_http_responses=include_http_responses,
+                http_request_headers=http_request_headers,
+                socket_list=request['tcp_connect'],
+                invalid_sockets=invalid_sockets
             )
         except HTTPError:
             raise

oonib/tests/test_web_connectivity.py

@@ -14,7 +14,7 @@ def tearDown(self):
     @defer.inlineCallbacks
     def test_http_request(self):
         value = yield self.web_connectivity_cache.http_request(
-                    'https://www.google.com/humans.txt')
+                    'https://www.google.com/humans.txt', {})
         self.assertEqual(
             value['body_length'], 286
         )