From 662d0d92bd800b988ccbf878d0f6e1a963568ff5 Mon Sep 17 00:00:00 2001
From: SomberNight <somber.night@protonmail.com>
Date: Wed, 24 Jun 2020 16:45:40 +0200
Subject: [PATCH] remote watchtower: enforce that SSL is used, on the
client-side
---
electrum/lnworker.py | 10 +++++++++-
electrum/tests/test_util.py | 15 ++++++++++++++-
electrum/util.py | 14 ++++++++++++++
3 files changed, 37 insertions(+), 2 deletions(-)
diff --git a/electrum/lnworker.py b/electrum/lnworker.py
index 8641367e0..a79ed23a6 100644
--- a/electrum/lnworker.py
+++ b/electrum/lnworker.py
@@ -17,6 +17,7 @@ from functools import partial
from collections import defaultdict
import concurrent
from concurrent import futures
+import urllib.parse
import dns.resolver
import dns.exception
@@ -36,7 +37,7 @@ from .bip32 import BIP32Node
from .util import bh2u, bfh, InvoiceError, resolve_dns_srv, is_ip_address, log_exceptions
from .util import ignore_exceptions, make_aiohttp_session, SilentTaskGroup
from .util import timestamp_to_datetime, random_shuffled_copy
-from .util import MyEncoder
+from .util import MyEncoder, is_private_netaddress
from .logging import Logger
from .lntransport import LNTransport, LNResponderTransport
from .lnpeer import Peer, LN_P2P_NETWORK_TIMEOUT
@@ -531,10 +532,17 @@ class LNWallet(LNWorker):
@log_exceptions
async def sync_with_remote_watchtower(self):
while True:
+ # periodically poll if the user updated 'watchtower_url'
await asyncio.sleep(5)
watchtower_url = self.config.get('watchtower_url')
if not watchtower_url:
continue
+ parsed_url = urllib.parse.urlparse(watchtower_url)
+ if not (parsed_url.scheme == 'https' or is_private_netaddress(parsed_url.hostname)):
+ self.logger.warning(f"got watchtower URL for remote tower but we won't use it! "
+ f"can only use HTTPS (except if private IP): not using {watchtower_url!r}")
+ continue
+ # try to sync with the remote watchtower
try:
async with make_aiohttp_session(proxy=self.network.proxy) as session:
watchtower = JsonRPCClient(session, watchtower_url)
diff --git a/electrum/tests/test_util.py b/electrum/tests/test_util.py
index 8802e9c91..af039ca21 100644
--- a/electrum/tests/test_util.py
+++ b/electrum/tests/test_util.py
@@ -2,7 +2,7 @@ from decimal import Decimal
from electrum.util import (format_satoshis, format_fee_satoshis, parse_URI,
is_hash256_str, chunks, is_ip_address, list_enabled_bits,
- format_satoshis_plain)
+ format_satoshis_plain, is_private_netaddress)
from . import ElectrumTestCase
@@ -148,3 +148,16 @@ class TestUtil(ElectrumTestCase):
self.assertFalse(is_ip_address("2001:db8:0:0:g:ff00:42:8329"))
self.assertFalse(is_ip_address("lol"))
self.assertFalse(is_ip_address(":@ASD:@AS\x77\x22\xff¬!"))
+
+ def test_is_private_netaddress(self):
+ self.assertTrue(is_private_netaddress("127.0.0.1"))
+ self.assertTrue(is_private_netaddress("127.5.6.7"))
+ self.assertTrue(is_private_netaddress("::1"))
+ self.assertTrue(is_private_netaddress("[::1]"))
+ self.assertTrue(is_private_netaddress("localhost"))
+ self.assertTrue(is_private_netaddress("localhost."))
+ self.assertFalse(is_private_netaddress("[::2]"))
+ self.assertFalse(is_private_netaddress("2a00:1450:400e:80d::200e"))
+ self.assertFalse(is_private_netaddress("[2a00:1450:400e:80d::200e]"))
+ self.assertFalse(is_private_netaddress("8.8.8.8"))
+ self.assertFalse(is_private_netaddress("example.com"))
diff --git a/electrum/util.py b/electrum/util.py
index d793ca9cf..8b7b612db 100644
--- a/electrum/util.py
+++ b/electrum/util.py
@@ -42,6 +42,7 @@ import time
from typing import NamedTuple, Optional
import ssl
import ipaddress
+from ipaddress import IPv4Address, IPv6Address
import random
import attr
@@ -1238,6 +1239,19 @@ def is_ip_address(x: Union[str, bytes]) -> bool:
return False
+def is_private_netaddress(host: str) -> bool:
+ if str(host) in ('localhost', 'localhost.',):
+ return True
+ if host[0] == '[' and host[-1] == ']': # IPv6
+ host = host[1:-1]
+ try:
+ ip_addr = ipaddress.ip_address(host) # type: Union[IPv4Address, IPv6Address]
+ return ip_addr.is_private
+ except ValueError:
+ pass # not an IP
+ return False
+
+
def list_enabled_bits(x: int) -> Sequence[int]:
"""e.g. 77 (0b1001101) --> (0, 2, 3, 6)"""
binary = bin(x)[2:]