From 21e637f5438e32dd0f6fdae17b0c908c5ab4d24b Mon Sep 17 00:00:00 2001 From: SomberNight Date: Wed, 13 May 2020 19:28:35 +0200 Subject: [PATCH] network: validate server peers sent by main server Data returned by the main server for request "server.peers.subscribe" is of course untrusted input. Previously if it contained e.g. invalid port numbers or IP addresses, it could kill the whole network taskgroup. (this might have only affected master and not released versions, which would only raise exceptions once the client actually tried to connect to an invalid host/port) --- electrum/network.py | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/electrum/network.py b/electrum/network.py index 928d5582c..9b0561fa0 100644 --- a/electrum/network.py +++ b/electrum/network.py @@ -77,7 +77,9 @@ NUM_RECENT_SERVERS = 20 def parse_servers(result: Sequence[Tuple[str, str, List[str]]]) -> Dict[str, dict]: - """ parse servers list into dict format""" + """Convert servers list (from protocol method "server.peers.subscribe") into dict format. + Also validate values, such as IP addresses and ports. + """ servers = {} for item in result: host = item[1] @@ -89,6 +91,7 @@ def parse_servers(result: Sequence[Tuple[str, str, List[str]]]) -> Dict[str, dic if re.match(r"[st]\d*", v): protocol, port = v[0], v[1:] if port == '': port = constants.net.DEFAULT_PORTS[protocol] + ServerAddr(host, port, protocol=protocol) # check if raises out[protocol] = port elif re.match("v(.?)+", v): version = v[1:] @@ -431,6 +434,7 @@ class Network(Logger, NetworkRetryManager[ServerAddr]): random.shuffle(server_peers) max_accepted_peers = len(constants.net.DEFAULT_SERVERS) + NUM_RECENT_SERVERS server_peers = server_peers[:max_accepted_peers] + # note that 'parse_servers' also validates the data (which is untrusted input!) self.server_peers = parse_servers(server_peers) self.notify('servers') async def get_relay_fee():