From de80f68e4d76ac2ae16f63089535bb00334c64f5 Mon Sep 17 00:00:00 2001
From: SomberNight <somber.night@protonmail.com>
Date: Tue, 3 Nov 2020 20:45:31 +0100
Subject: [PATCH] interface: validate protocol-version negotiation on
 client-side too

related: https://github.com/romanz/electrs/issues/314
---
 electrum/interface.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/electrum/interface.py b/electrum/interface.py
index de2364549..1bd666511 100644
--- a/electrum/interface.py
+++ b/electrum/interface.py
@@ -631,6 +631,9 @@ class Interface(Logger):
                 raise GracefulDisconnect(e)  # probably 'unsupported protocol version'
             if exit_early:
                 return
+            if ver[1] != version.PROTOCOL_VERSION:
+                raise GracefulDisconnect(f'server violated protocol-version-negotiation. '
+                                         f'we asked for {version.PROTOCOL_VERSION!r}, they sent {ver[1]!r}')
             if not self.network.check_interface_against_healthy_spread_of_connected_servers(self):
                 raise GracefulDisconnect(f'too many connected servers already '
                                          f'in bucket {self.bucket_based_on_ipaddress()}')