Captchas now work on registration. Missing x-forwarded-for config arg support. Missing reloading a new captcha on the web client / displaying a sensible error message.

synapse/api/errors.py

@@ -29,7 +29,8 @@ class Codes(object):
     NOT_FOUND = "M_NOT_FOUND"
     UNKNOWN_TOKEN = "M_UNKNOWN_TOKEN"
     LIMIT_EXCEEDED = "M_LIMIT_EXCEEDED"
-    NEEDS_CAPTCHA = "M_NEEDS_CAPTCHA"
+    CAPTCHA_NEEDED = "M_CAPTCHA_NEEDED"
+    CAPTCHA_INVALID = "M_CAPTCHA_INVALID"
 
 
 class CodeMessageException(Exception):
@@ -102,6 +103,19 @@ class StoreError(SynapseError):
     pass
 
 
+class InvalidCaptchaError(SynapseError):
+    def __init__(self, code=400, msg="Invalid captcha.", error_url=None,
+                 errcode=Codes.CAPTCHA_INVALID):
+        super(InvalidCaptchaError, self).__init__(code, msg, errcode)
+        self.error_url = error_url
+
+    def error_dict(self):
+        return cs_error(
+            self.msg,
+            self.errcode,
+            error_url=self.error_url,
+        )
+
 class LimitExceededError(SynapseError):
     """A client has sent too many requests and is being throttled.
     """

synapse/handlers/register.py

@@ -17,7 +17,7 @@
 from twisted.internet import defer
 
 from synapse.types import UserID
-from synapse.api.errors import SynapseError, RegistrationError
+from synapse.api.errors import SynapseError, RegistrationError, InvalidCaptchaError
 from ._base import BaseHandler
 import synapse.util.stringutils as stringutils
 from synapse.http.client import PlainHttpClient
@@ -38,7 +38,7 @@ class RegistrationHandler(BaseHandler):
         self.distributor.declare("registered_user")
 
     @defer.inlineCallbacks
-    def register(self, localpart=None, password=None, threepidCreds=None):
+    def register(self, localpart=None, password=None, threepidCreds=None, captcha_info={}):
         """Registers a new client on the server.
 
         Args:
@@ -51,6 +51,19 @@ class RegistrationHandler(BaseHandler):
         Raises:
             RegistrationError if there was a problem registering.
         """
+        if captcha_info:
+            captcha_response = yield self._validate_captcha(
+                captcha_info["ip"], 
+                captcha_info["private_key"],
+                captcha_info["challenge"],
+                captcha_info["response"]
+            )
+            if not captcha_response["valid"]:
+                raise InvalidCaptchaError(
+                    error_url=captcha_response["error_url"]
+                )
+            else:
+                logger.info("Valid captcha entered from %s", captcha_info["ip"])
 
         if threepidCreds:
             for c in threepidCreds:
@@ -153,5 +166,37 @@ class RegistrationHandler(BaseHandler):
         )
         defer.returnValue(data)
         
+    @defer.inlineCallbacks
+    def _validate_captcha(self, ip_addr, private_key, challenge, response):
+        """Validates the captcha provided.
+        
+        Returns:
+            dict: Containing 'valid'(bool) and 'error_url'(str) if invalid.
+        
+        """
+        response = yield self._submit_captcha(ip_addr, private_key, challenge, response)
+        # parse Google's response. Lovely format..
+        lines = response.split('\n')
+        json = {
+            "valid": lines[0] == 'true',
+            "error_url": "http://www.google.com/recaptcha/api/challenge?error=%s" % lines[1]
+        }
+        defer.returnValue(json)
+        
+    @defer.inlineCallbacks
+    def _submit_captcha(self, ip_addr, private_key, challenge, response):
+        client = PlainHttpClient(self.hs)
+        data = yield client.post_urlencoded_get_raw(
+            "www.google.com:80",
+            "/recaptcha/api/verify",
+            accept_partial=True,  # twisted dislikes google's response, no content length.
+            args={ 
+                'privatekey': private_key, 
+                'remoteip': ip_addr,
+                'challenge': challenge,
+                'response': response
+            }
+        )
+        defer.returnValue(data)
         
 

synapse/http/client.py

@@ -16,7 +16,7 @@
 
 from twisted.internet import defer, reactor
 from twisted.internet.error import DNSLookupError
-from twisted.web.client import _AgentBase, _URI, readBody, FileBodyProducer
+from twisted.web.client import _AgentBase, _URI, readBody, FileBodyProducer, PartialDownloadError
 from twisted.web.http_headers import Headers
 
 from synapse.http.endpoint import matrix_endpoint
@@ -188,6 +188,32 @@ class TwistedHttpClient(HttpClient):
         body = yield readBody(response)
 
         defer.returnValue(json.loads(body))
+        
+    # XXX FIXME : I'm so sorry.
+    @defer.inlineCallbacks
+    def post_urlencoded_get_raw(self, destination, path, accept_partial=False, args={}):
+        if destination in _destination_mappings:
+            destination = _destination_mappings[destination]
+
+        query_bytes = urllib.urlencode(args, True)
+
+        response = yield self._create_request(
+            destination.encode("ascii"),
+            "POST",
+            path.encode("ascii"),
+            producer=FileBodyProducer(StringIO(urllib.urlencode(args))),
+            headers_dict={"Content-Type": ["application/x-www-form-urlencoded"]}
+        )
+
+        try:
+            body = yield readBody(response)
+            defer.returnValue(body)
+        except PartialDownloadError as e:
+            if accept_partial:
+                defer.returnValue(e.response)
+            else:
+                raise e
+        
 
     @defer.inlineCallbacks
     def _create_request(self, destination, method, path_bytes, param_bytes=b"",

synapse/rest/register.py

@@ -51,15 +51,38 @@ class RegisterRestServlet(RestServlet):
         if 'threepidCreds' in register_json:
             threepidCreds = register_json['threepidCreds']
             
+        captcha = {}
         if self.hs.config.enable_registration_captcha:
-            if not "challenge" in register_json or not "response" in register_json:
+            challenge = None
-                raise SynapseError(400, "Captcha response is required", errcode=Codes.NEEDS_CAPTCHA)
+            user_response = None
+            try:
+                captcha_type = register_json["captcha"]["type"]
+                if captcha_type != "m.login.recaptcha":
+                    raise SynapseError(400, "Sorry, only m.login.recaptcha requests are supported.")
+                challenge = register_json["captcha"]["challenge"]
+                user_response = register_json["captcha"]["response"]
+            except KeyError:
+                raise SynapseError(400, "Captcha response is required", errcode=Codes.CAPTCHA_NEEDED)
+            
+            # TODO determine the source IP : May be an X-Forwarding-For header depending on config
+            ip_addr = request.getClientIP()
+            #if self.hs.config.captcha_ip_origin_is_x_forwarded:
+            #    # use the header
+            
+            captcha = {
+                "ip": ip_addr,
+                "private_key": self.hs.config.recaptcha_private_key,
+                "challenge": challenge,
+                "response": user_response
+            }
+            
 
         handler = self.handlers.registration_handler
         (user_id, token) = yield handler.register(
             localpart=desired_user_id,
             password=password,
-            threepidCreds=threepidCreds)
+            threepidCreds=threepidCreds,
+            captcha_info=captcha)
 
         result = {
             "user_id": user_id,