use signature keyid instead of object actor to fetch actor

relay/misc.py

@@ -106,20 +106,6 @@ def sign_signing_string(sigstring, key):
 	return base64.b64encode(sigdata).decode('utf-8')
 
 
-def split_signature(sig):
-	default = {"headers": "date"}
-
-	sig = sig.strip().split(',')
-
-	for chunk in sig:
-		k, _, v = chunk.partition('=')
-		v = v.strip('\"')
-		default[k] = v
-
-	default['headers'] = default['headers'].split()
-	return default
-
-
 async def fetch_actor_key(actor):
 	actor_data = await request(actor)
 
@@ -250,29 +236,19 @@ async def request(uri, data=None, force=False, sign_headers=True, activity=True)
 		traceback.print_exc()
 
 
-async def validate_signature(actor, http_request):
-	pubkey = await fetch_actor_key(actor)
-
-	if not pubkey:
-		return False
-
-	logging.debug(f'actor key: {pubkey}')
-
+async def validate_signature(actor, signature, http_request):
 	headers = {key.lower(): value for key, value in http_request.headers.items()}
 	headers['(request-target)'] = ' '.join([http_request.method.lower(), http_request.path])
 
-	sig = split_signature(headers['signature'])
-	logging.debug(f'sigdata: {sig}')
-
-	sigstring = build_signing_string(headers, sig['headers'])
+	sigstring = build_signing_string(headers, signature['headers'])
 	logging.debug(f'sigstring: {sigstring}')
 
-	sign_alg, _, hash_alg = sig['algorithm'].partition('-')
+	sign_alg, _, hash_alg = signature['algorithm'].partition('-')
 	logging.debug(f'sign alg: {sign_alg}, hash alg: {hash_alg}')
 
-	sigdata = base64.b64decode(sig['signature'])
+	sigdata = base64.b64decode(signature['signature'])
 
-	pkcs = PKCS1_v1_5.new(pubkey)
+	pkcs = PKCS1_v1_5.new(actor.PUBKEY)
 	h = HASHES[hash_alg].new()
 	h.update(sigstring.encode('ascii'))
 	result = pkcs.verify(h, sigdata)
@@ -333,6 +309,22 @@ class DotDict(dict):
 			raise JSONDecodeError('Invalid body', data, 1)
 
 
+	@classmethod
+	def new_from_signature(cls, sig):
+		data = cls({})
+
+		for chunk in sig.strip().split(','):
+			key, value = chunk.split('=', 1)
+			value = value.strip('\"')
+
+			if key == 'headers':
+				value = value.split()
+
+			data[key.lower()] = value
+
+		return data
+
+
 	def to_json(self, indent=None):
 		return json.dumps(self, indent=indent)
 
@@ -435,6 +427,11 @@ class Message(DotDict):
 
 
 	# actor properties
+	@property
+	def PUBKEY(self):
+		return RSA.import_key(self.pubkey)
+
+
 	@property
 	def pubkey(self):
 		return self.publicKey.publicKeyPem

relay/views.py

@@ -6,7 +6,7 @@ from pathlib import Path
 
 from . import __version__, misc
 from .http_debug import STATS
-from .misc import Message, Response, WKNodeinfo
+from .misc import DotDict, Message, Response, WKNodeinfo
 from .processors import run_processor
 
 
@@ -78,11 +78,14 @@ async def inbox(request):
 	database = request.app.database
 
 	## reject if missing signature header
-	if 'signature' not in request.headers:
+	try:
+		signature = DotDict.new_from_signature(request.headers['signature'])
+
+	except KeyError:
 		logging.verbose('Actor missing signature header')
 		raise HTTPUnauthorized(body='missing signature')
 
-	## read message and get actor id and domain
+	## read message
 	try:
 		data = await request.json(loads=Message.new_from_json)
 
@@ -96,22 +99,22 @@ async def inbox(request):
 		logging.verbose('Failed to parse inbox message')
 		return Response.new_error(400, 'failed to parse message', 'json')
 
-	software = await misc.fetch_nodeinfo(data.domain)
-	actor = await misc.request(data.actorid)
+	actor = await misc.request(signature.keyid)
+	software = await misc.fetch_nodeinfo(actor.domain)
 
 	## reject if actor is empty
 	if not actor:
-		logging.verbose(f'Failed to fetch actor: {data.actorid}')
+		logging.verbose(f'Failed to fetch actor: {actor.id}')
 		return Response.new_error(400, 'failed to fetch actor', 'json')
 
 	## reject if the actor isn't whitelisted while the whiltelist is enabled
-	elif config.whitelist_enabled and not config.is_whitelisted(data.domain):
-		logging.verbose(f'Rejected actor for not being in the whitelist: {data.actorid}')
+	elif config.whitelist_enabled and not config.is_whitelisted(actor.domain):
+		logging.verbose(f'Rejected actor for not being in the whitelist: {actor.id}')
 		return Response.new_error(403, 'access denied', 'json')
 
 	## reject if actor is banned
-	if request.app['config'].is_banned(data.domain):
-		logging.verbose(f'Ignored request from banned actor: {data.actorid}')
+	if request.app['config'].is_banned(actor.domain):
+		logging.verbose(f'Ignored request from banned actor: {actor.id}')
 		return Response.new_error(403, 'access denied', 'json')
 
 	## reject if software used by actor is banned
@@ -120,13 +123,13 @@ async def inbox(request):
 		return Response.new_error(403, 'access denied', 'json')
 
 	## reject if the signature is invalid
-	if not (await misc.validate_signature(data.actorid, request)):
-		logging.verbose(f'signature validation failed for: {data.actorid}')
+	if not (await misc.validate_signature(actor, signature, request)):
+		logging.verbose(f'signature validation failed for: {actor.id}')
 		return Response.new_error(401, 'signature check failed', 'json')
 
 	## reject if activity type isn't 'Follow' and the actor isn't following
-	if data['type'] != 'Follow' and not database.get_inbox(data.domain):
-		logging.verbose(f'Rejected actor for trying to post while not following: {data.actorid}')
+	if data['type'] != 'Follow' and not database.get_inbox(actor.domain):
+		logging.verbose(f'Rejected actor for trying to post while not following: {actor.id}')
 		return Response.new_error(401, 'access denied', 'json')
 
 	logging.debug(f">> payload {data}")