From 3851ce5dd1a26550f546aafc4438d30623d54a33 Mon Sep 17 00:00:00 2001
From: SomberNight <somber.night@protonmail.com>
Date: Tue, 18 Jan 2022 19:50:46 +0100
Subject: [PATCH] scripts: add "update_default_servers.py"

---
 electrum/network.py                        | 21 +++++++-
 electrum/scripts/update_default_servers.py | 63 ++++++++++++++++++++++
 2 files changed, 82 insertions(+), 2 deletions(-)
 create mode 100755 electrum/scripts/update_default_servers.py

diff --git a/electrum/network.py b/electrum/network.py
index ce222ea1e..904edb01d 100644
--- a/electrum/network.py
+++ b/electrum/network.py
@@ -1331,11 +1331,19 @@ class Network(Logger, NetworkRetryManager[ServerAddr]):
         session = self.interface.session
         return parse_servers(await session.send_request('server.peers.subscribe'))
 
-    async def send_multiple_requests(self, servers: Sequence[ServerAddr], method: str, params: Sequence):
+    async def send_multiple_requests(
+            self,
+            servers: Sequence[ServerAddr],
+            method: str,
+            params: Sequence,
+            *,
+            timeout: int = None,
+    ):
+        if timeout is None:
+            timeout = self.get_network_timeout_seconds(NetworkTimeout.Urgent)
         responses = dict()
         async def get_response(server: ServerAddr):
             interface = Interface(network=self, server=server, proxy=self.proxy)
-            timeout = self.get_network_timeout_seconds(NetworkTimeout.Urgent)
             try:
                 await asyncio.wait_for(interface.ready, timeout)
             except BaseException as e:
@@ -1350,3 +1358,12 @@ class Network(Logger, NetworkRetryManager[ServerAddr]):
             for server in servers:
                 await group.spawn(get_response(server))
         return responses
+
+    async def prune_offline_servers(self, hostmap):
+        peers = filter_protocol(hostmap, allowed_protocols=("t", "s",))
+        timeout = self.get_network_timeout_seconds(NetworkTimeout.Generic)
+        replies = await self.send_multiple_requests(peers, 'blockchain.headers.subscribe', [], timeout=timeout)
+        servers_replied = {serveraddr.host for serveraddr in replies.keys()}
+        servers_dict = {k: v for k, v in hostmap.items()
+                        if k in servers_replied}
+        return servers_dict
diff --git a/electrum/scripts/update_default_servers.py b/electrum/scripts/update_default_servers.py
new file mode 100755
index 000000000..04a6f970f
--- /dev/null
+++ b/electrum/scripts/update_default_servers.py
@@ -0,0 +1,63 @@
+#!/usr/bin/env python3
+# This script prints a new "servers.json" to stdout.
+# It prunes the offline servers from the existing list (note: run with Tor proxy to keep .onions),
+# and adds new servers from provided file(s) of candidate servers.
+# A file of new candidate servers can be created via e.g.:
+# $ ./electrum/scripts/servers.py > reply.txt
+
+import asyncio
+import sys
+import json
+
+from electrum.network import Network
+from electrum.util import create_and_start_event_loop, log_exceptions
+from electrum.simple_config import SimpleConfig
+from electrum import constants
+
+try:
+    fname1 = sys.argv[1]
+    fname2 = sys.argv[2] if len(sys.argv) > 2 else None
+except Exception:
+    print("usage: update_default_servers.py <file1> [<file2>]")
+    print("       - the file(s) should contain json hostmaps for new servers to be added")
+    print("       - if two files are provided, their intersection is used (peers found in both).\n"
+          "         file1 should have the newer data.")
+    sys.exit(1)
+
+
+def get_newly_added_servers(fname1, fname2=None):
+    with open(fname1) as f:
+        res_hostmap = json.loads(f.read())
+    if fname2 is not None:
+        with open(fname2) as f:
+            dict2 = json.loads(f.read())
+        common_set = set.intersection(set(res_hostmap), set(dict2))
+        res_hostmap = {k: v for k, v in res_hostmap.items() if k in common_set}
+    return res_hostmap
+
+
+# testnet?
+#constants.set_testnet()
+config = SimpleConfig({'testnet': False})
+
+loop, stopping_fut, loop_thread = create_and_start_event_loop()
+network = Network(config)
+network.start()
+
+@log_exceptions
+async def f():
+    try:
+        # prune existing servers
+        old_servers_all = constants.net.DEFAULT_SERVERS
+        old_servers_online = await network.prune_offline_servers(constants.net.DEFAULT_SERVERS)
+        # add new servers
+        newly_added_servers = get_newly_added_servers(fname1, fname2)
+        res_servers = {**old_servers_online, **newly_added_servers}
+
+        print(json.dumps(res_servers, indent=4, sort_keys=True))
+        print(f"got reply from {len(old_servers_online)}/{len(old_servers_all)} old servers", file=sys.stderr)
+        print(f"{len(newly_added_servers)=}. total: {len(res_servers)=}", file=sys.stderr)
+    finally:
+        stopping_fut.set_result(1)
+
+asyncio.run_coroutine_threadsafe(f(), loop)