feature: allow channels to register with public key

Channels can include a public key when registering a new subscription
channel. This public key should match the public key used to send
subscription updates later.

NOTE: this patch changes the format of the endpoint URLs, & the content
of the endpoint URL token. This change also requires that ChannelIDs be
normalized to dashed format, (e.g. a lower case, dash delimited string
"deadbeef-0000-0000-deca-fbad11112222") This is the default mechanism
used by Firefox for UUID generation. It is STRONGLY urged that clients
normalize UUIDs used for ChannelIDs and User Agent IDs. While this
should not break existing clients, additional testing may be required.

Closes #326

autopush/db.py

@@ -52,6 +52,18 @@ def hasher(uaid):
     return uaid
 
 
+def normalize_id(id):
+    if not id:
+        return id
+    if (len(id) == 36 and
+            id[8] == id[13] == id[18] == id[23] == '-'):
+        return id.lower()
+    raw = filter(lambda x: x in '0123456789abcdef', id.lower())
+    if len(raw) != 32:
+        raise ValueError("Invalid UUID")
+    return '-'.join((raw[:8], raw[8:12], raw[12:16], raw[16:20], raw[20:]))
+
+
 def make_rotating_tablename(prefix, delta=0):
     """Creates a tablename for table rotation based on a prefix with a given
     month delta."""
@@ -261,7 +273,8 @@ def save_notification(self, uaid, chid, version):
             cond = "attribute_not_exists(version) or version < :ver"
             conn.put_item(
                 self.table.table_name,
-                item=self.encode(dict(uaid=hasher(uaid), chid=chid,
+                item=self.encode(dict(uaid=hasher(uaid),
+                                      chid=normalize_id(chid),
                                       version=version)),
                 condition_expression=cond,
                 expression_attribute_values={
@@ -281,10 +294,12 @@ def delete_notification(self, uaid, chid, version=None):
         """
         try:
             if version:
-                self.table.delete_item(uaid=hasher(uaid), chid=chid,
+                self.table.delete_item(uaid=hasher(uaid),
+                                       chid=normalize_id(chid),
                                        expected={"version__eq": version})
             else:
-                self.table.delete_item(uaid=hasher(uaid), chid=chid)
+                self.table.delete_item(uaid=hasher(uaid),
+                                       chid=normalize_id(chid))
             return True
         except ProvisionedThroughputExceededException:
             self.metrics.increment("error.provisioned.delete_notification")
@@ -312,7 +327,8 @@ def register_channel(self, uaid, channel_id):
         db_key = self.encode({"uaid": hasher(uaid), "chidmessageid": " "})
         # Generate our update expression
         expr = "ADD chids :channel_id"
-        expr_values = self.encode({":channel_id": set([channel_id])})
+        expr_values = self.encode({":channel_id":
+                                  set([normalize_id(channel_id)])})
         conn.update_item(
             self.table.table_name,
             db_key,
@@ -327,7 +343,8 @@ def unregister_channel(self, uaid, channel_id, **kwargs):
         conn = self.table.connection
         db_key = self.encode({"uaid": hasher(uaid), "chidmessageid": " "})
         expr = "DELETE chids :channel_id"
-        expr_values = self.encode({":channel_id": set([channel_id])})
+        expr_values = self.encode({":channel_id":
+                                   set([normalize_id(channel_id)])})
 
         result = conn.update_item(
             self.table.table_name,
@@ -375,7 +392,7 @@ def store_message(self, uaid, channel_id, message_id, ttl, data=None,
         with the message id"""
         item = dict(
             uaid=hasher(uaid),
-            chidmessageid="%s:%s" % (channel_id, message_id),
+            chidmessageid="%s:%s" % (normalize_id(channel_id), message_id),
             data=data,
             headers=headers,
             ttl=ttl,
@@ -407,7 +424,7 @@ def update_message(self, uaid, channel_id, message_id, ttl, data=None,
             item["headers"] = headers
             item["data"] = data
         try:
-            chidmessageid = "%s:%s" % (channel_id, message_id)
+            chidmessageid = "%s:%s" % (normalize_id(channel_id), message_id)
             db_key = self.encode({"uaid": hasher(uaid),
                                   "chidmessageid": chidmessageid})
             expr = ("SET #tl=:ttl, #ts=:timestamp,"
@@ -439,14 +456,16 @@ def delete_message(self, uaid, channel_id, message_id, updateid=None):
             try:
                 self.table.delete_item(
                     uaid=hasher(uaid),
-                    chidmessageid="%s:%s" % (channel_id, message_id),
+                    chidmessageid="%s:%s" % (normalize_id(channel_id),
+                                             message_id),
                     expected={'updateid__eq': updateid})
             except ConditionalCheckFailedException:
                 return False
         else:
             self.table.delete_item(
                 uaid=hasher(uaid),
-                chidmessageid="%s:%s" % (channel_id, message_id))
+                chidmessageid="%s:%s" % (normalize_id(channel_id),
+                                         message_id))
         return True
 
     def delete_messages(self, uaid, chidmessageids):
@@ -463,7 +482,7 @@ def delete_messages_for_channel(self, uaid, channel_id):
         """Deletes all messages for a uaid/channel_id"""
         results = self.table.query_2(
             uaid__eq=hasher(uaid),
-            chidmessageid__beginswith="%s:" % channel_id,
+            chidmessageid__beginswith="%s:" % normalize_id(channel_id),
             consistent=True,
             attributes=("chidmessageid",),
         )

autopush/endpoint.py

@@ -42,7 +42,8 @@
 
 from autopush.db import (
     generate_last_connect,
-    hasher
+    hasher,
+    normalize_id,
 )
 from autopush.router.interface import RouterException
 from autopush.utils import (
@@ -174,8 +175,8 @@ def chid(self):
     @chid.setter
     def chid(self, value):
         """Set the ChannelID and record to _client_info"""
-        self._chid = value
-        self._client_info["channelID"] = value
+        self._chid = normalize_id(value)
+        self._client_info["channelID"] = self._chid
 
     def _init_info(self):
         """Returns a dict of additional client data"""
@@ -309,7 +310,7 @@ def _invalid_auth(self, fail):
         log.msg("Invalid bearer token: " + message, **self._client_info)
         raise VapidAuthException("Invalid bearer token: " + message)
 
-    def _process_auth(self, result):
+    def _process_auth(self, result, keys):
         """Process the optional VAPID auth token.
 
         VAPID requires two headers to be present;
@@ -322,28 +323,26 @@ def _process_auth(self, result):
         # No auth present, so it's not a VAPID call.
         if not authorization:
             return result
-
-        header_info = parse_header(self.request.headers.get('crypto-key'))
-        if not header_info:
+        if not keys:
             raise VapidAuthException("Missing Crypto-Key")
-        values = header_info[-1]
-        if isinstance(values, dict):
-            crypto_key = values.get('p256ecdsa')
-            try:
-                (auth_type, token) = authorization.split(' ', 1)
-            except ValueError:
-                raise VapidAuthException("Invalid Authorization header")
-            # if it's a bearer token containing what may be a JWT
-            if auth_type.lower() == AUTH_SCHEME and '.' in token:
-                d = deferToThread(extract_jwt, token, crypto_key)
-                d.addCallback(self._store_auth, crypto_key, token, result)
-                d.addErrback(self._invalid_auth)
-                return d
-            # otherwise, it's not, so ignore the VAPID data.
-            return result
-        else:
+        if not isinstance(keys, dict):
+            raise VapidAuthException("Invalid Crypto-Key")
+        crypto_key = keys.get('p256ecdsa')
+        if not crypto_key:
             raise VapidAuthException("Invalid bearer token: "
                                      "improperly specified crypto-key")
+        try:
+            (auth_type, token) = authorization.split(' ', 1)
+        except ValueError:
+            raise VapidAuthException("Invalid Authorization header")
+        # if it's a bearer token containing what may be a JWT
+        if auth_type.lower() == AUTH_SCHEME and '.' in token:
+            d = deferToThread(extract_jwt, token, crypto_key)
+            d.addCallback(self._store_auth, crypto_key, token, result)
+            d.addErrback(self._invalid_auth)
+            return d
+        # otherwise, it's not, so ignore the VAPID data.
+        return result
 
 
 class MessageHandler(AutoendpointHandler):
@@ -404,17 +403,27 @@ class EndpointHandler(AutoendpointHandler):
     #                    Cyclone HTTP Methods
     #############################################################
     @cyclone.web.asynchronous
-    def put(self, token):
+    def put(self, api_ver="v0", token=None):
         """HTTP PUT Handler
 
         Primary entry-point to handling a notification for a push client.
 
         """
         self.start_time = time.time()
-        fernet = self.ap_settings.fernet
-
-        d = deferToThread(fernet.decrypt, token.encode('utf8'))
-        d.addCallback(self._process_auth)
+        public_key = None
+        keys = {}
+        crypto_key = self.request.headers.get('crypto-key')
+        if crypto_key:
+            header_info = parse_header(crypto_key)
+            keys = header_info[-1]
+            if isinstance(keys, dict):
+                public_key = keys.get('p256ecdsa')
+
+        d = deferToThread(self.ap_settings.parse_endpoint,
+                          token,
+                          api_ver,
+                          public_key)
+        d.addCallback(self._process_auth, keys)
         d.addCallback(self._token_valid)
         d.addErrback(self._auth_err)
         d.addErrback(self._token_err)
@@ -426,11 +435,10 @@ def put(self, token):
     #############################################################
     def _token_valid(self, result):
         """Called after the token is decrypted successfully"""
-        info = result.split(":")
-        if len(info) != 2:
+        if len(result) != 2:
             raise ValueError("Wrong subscription token components")
 
-        self.uaid, self.chid = info
+        self.uaid, self.chid = result
         d = deferToThread(self.ap_settings.router.get_uaid, self.uaid)
         d.addCallback(self._uaid_lookup_results)
         d.addErrback(self._uaid_not_found_err)

autopush/logging.py

@@ -15,7 +15,8 @@
 import sys
 
 import raven
-from eliot import add_destination, fields, Logger, MessageType
+from eliot import (add_destination, fields,
+                   Logger, MessageType)
 from twisted.python.log import textFromEventDict, startLoggingWithObserver
 
 HOSTNAME = socket.getfqdn()

autopush/main.py

@@ -467,7 +467,8 @@ def endpoint_main(sysargs=None, use_files=True):
 
     # Endpoint HTTP router
     site = cyclone.web.Application([
-        (r"/push/([^\/]+)", EndpointHandler, dict(ap_settings=settings)),
+        (r"/push/(?:(v\d+)\/)?([^\/]+)", EndpointHandler,
+         dict(ap_settings=settings)),
         (r"/m/([^\/]+)", MessageHandler, dict(ap_settings=settings)),
         # PUT /register/ => connect info
         # GET /register/uaid => chid + endpoint

autopush/router/webpush.py

@@ -19,6 +19,7 @@
 from autopush.protocol import IgnoreBody
 from autopush.router.interface import RouterException, RouterResponse
 from autopush.router.simple import SimpleRouter
+from autopush.db import normalize_id
 
 TTL_URL = "https://webpush-wg.github.io/webpush-protocol/#rfc.section.6.2"
 
@@ -72,7 +73,8 @@ def preflight_check(self, uaid, channel_id):
             self.ap_settings.message_tables[month_table].all_channels,
             uaid=uaid)
 
-        if not exists or channel_id not in chans:
+        if (not exists or channel_id.lower() not
+                in map(lambda x: normalize_id(x), chans)):
             raise RouterException("No such subscription", status_code=404,
                                   log_exception=False, errno=106)
         returnValue(month_table)
@@ -84,7 +86,8 @@ def _send_notification(self, uaid, node_id, notification):
         headers for the notification.
 
         """
-        payload = {"channelID": notification.channel_id,
+        # Firefox currently requires channelIDs to be '-' formatted.
+        payload = {"channelID": normalize_id(notification.channel_id),
                    "version": notification.version,
                    "ttl": notification.ttl or 0,
                    "timestamp": int(time.time()),

autopush/settings.py

@@ -2,7 +2,10 @@
 import datetime
 import socket
 
+from hashlib import sha256
+
 from cryptography.fernet import Fernet, MultiFernet
+from cryptography.hazmat.primitives import constant_time
 from twisted.internet import reactor
 from twisted.internet.defer import (
     inlineCallbacks,
@@ -232,6 +235,7 @@ def update_rotating_tables(self):
         self.current_msg_month = message_table.table_name
         self.message_tables[self.current_msg_month] = \
             Message(message_table, self.metrics)
+
         returnValue(True)
 
     def update(self, **kwargs):
@@ -248,7 +252,57 @@ def update(self, **kwargs):
             else:
                 setattr(self, key, val)
 
-    def make_endpoint(self, uaid, chid):
-        """ Create an endpoint from the identifiers"""
-        return self.endpoint_url + '/push/' + \
-            self.fernet.encrypt((uaid + ':' + chid).encode('utf8'))
+    def make_endpoint(self, uaid, chid, key=None):
+        """Create an v1 or v2 endpoint from the indentifiers.
+
+        Both endpoints use bytes instead of hex to reduce ID length.
+        v0 is uaid.hex + ':' + chid.hex and is deprecated.
+        v1 is the uaid + chid
+        v2 is the uaid + chid + sha256(key).bytes
+
+        :param uaid: User Agent Identifier
+        :param chid: Channel or Subscription ID
+        :param key: Optional provided Public Key
+        :returns: Push endpoint
+
+        """
+        root = self.endpoint_url + '/push/'
+        base = (uaid.replace('-', '').decode("hex") +
+                chid.replace('-', '').decode("hex"))
+
+        if key is None:
+            return root + 'v1/' + self.fernet.encrypt(base).strip('=')
+
+        return root + 'v2/' + self.fernet.encrypt(base + sha256(key).digest())
+
+    def parse_endpoint(self, token, version="v0", public_key=None):
+        """Parse an endpoint into component elements of UAID, CHID and optional
+        key hash if v2
+
+        :param token: The obscured subscription data.
+        :param version: This is the API version of the token.
+        :param public_key: the public key (from Encryption-Key: p256ecdsa=)
+
+        :raises ValueError: In the case of a malformed endpoint.
+
+        :returns: a tuple containing the (UAID, CHID)
+
+        """
+
+        token = self.fernet.decrypt(token.encode('utf8'))
+
+        if version == 'v0':
+            if ':' not in token:
+                raise ValueError("Corrupted push token")
+            return tuple(token.split(':'))
+        if version == 'v1' and len(token) != 32:
+            raise ValueError("Corrupted push token")
+        if version == 'v2':
+            if len(token) != 64:
+                raise ValueError("Corrupted push token")
+            if not public_key:
+                raise ValueError("Invalid key data")
+            if not constant_time.bytes_eq(sha256(public_key).digest(),
+                                          token[32:]):
+                raise ValueError("Key mismatch")
+        return (token[:16].encode('hex'), token[16:32].encode('hex'))