From 380d7edea29415cbaa3dab6d5b3b2449e3a2df1f Mon Sep 17 00:00:00 2001
From: f321x <f@f321x.com>
Date: Thu, 11 Dec 2025 15:07:21 +0100
Subject: [PATCH 1/3] lnpeer: remove support for zlib compression

Must not be used anymore according to bolt 7:
https://github.com/lightning/bolts/blob/0cf21511a781c295b9374aeaef37cf9c4d193502/07-routing-gossip.md?plain=1#L600
---
 electrum/lnpeer.py | 11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/electrum/lnpeer.py b/electrum/lnpeer.py
index fe0516b8d..98e3a292d 100644
--- a/electrum/lnpeer.py
+++ b/electrum/lnpeer.py
@@ -4,7 +4,6 @@
 # Distributed under the MIT software license, see the accompanying
 # file LICENCE or http://www.opensource.org/licenses/mit-license.php
 
-import zlib
 from collections import OrderedDict, defaultdict
 import asyncio
 import os
@@ -786,13 +785,11 @@ class Peer(Logger, EventListener):
             first_blocknum=first_block,
             number_of_blocks=num_blocks)
 
-    def decode_short_ids(self, encoded):
-        if encoded[0] == 0:
-            decoded = encoded[1:]
-        elif encoded[0] == 1:
-            decoded = zlib.decompress(encoded[1:])
-        else:
+    @staticmethod
+    def decode_short_ids(encoded):
+        if encoded[0] != 0:
             raise Exception(f'decode_short_ids: unexpected first byte: {encoded[0]}')
+        decoded = encoded[1:]
         ids = [decoded[i:i+8] for i in range(0, len(decoded), 8)]
         return ids
 

From 1ebb937d467c229a764c971718f93f2ec6b663d9 Mon Sep 17 00:00:00 2001
From: f321x <f@f321x.com>
Date: Thu, 11 Dec 2025 15:40:23 +0100
Subject: [PATCH 2/3] lnpeer: decode_short_ids: check length of short ids

- if `encoded_short_ids` does not decode into a whole number of `short_channel_id`:
  - MAY send a `warning`.
  - MAY close the connection.
https://github.com/lightning/bolts/blob/0cf21511a781c295b9374aeaef37cf9c4d193502/07-routing-gossip.md?plain=1#L674

# Conflicts:
#	electrum/lnpeer.py
---
 electrum/lnpeer.py | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/electrum/lnpeer.py b/electrum/lnpeer.py
index 98e3a292d..55a591c46 100644
--- a/electrum/lnpeer.py
+++ b/electrum/lnpeer.py
@@ -787,7 +787,9 @@ class Peer(Logger, EventListener):
 
     @staticmethod
     def decode_short_ids(encoded):
-        if encoded[0] != 0:
+        if len(encoded) < 1 or (len(encoded) - 1) % 8 != 0:
+            raise Exception(f'decode_short_ids: invalid size: {len(encoded)=}')
+        elif encoded[0] != 0:
             raise Exception(f'decode_short_ids: unexpected first byte: {encoded[0]}')
         decoded = encoded[1:]
         ids = [decoded[i:i+8] for i in range(0, len(decoded), 8)]

From b4fc39ca5fbbdc49f2a38d2d371001e2f41e9239 Mon Sep 17 00:00:00 2001
From: f321x <f@f321x.com>
Date: Thu, 11 Dec 2025 15:53:30 +0100
Subject: [PATCH 3/3] test: lnpeer: add test_decode_short_ids

---
 tests/test_lnpeer.py | 39 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/tests/test_lnpeer.py b/tests/test_lnpeer.py
index 941a4a12f..1baf3b156 100644
--- a/tests/test_lnpeer.py
+++ b/tests/test_lnpeer.py
@@ -634,6 +634,45 @@ class TestPeer(ElectrumTestCase):
             w2.register_hold_invoice(payment_hash, cb)
 
 
+class TestPeerUtils(TestPeer):
+
+    def test_decode_short_ids(self):
+        """
+        Test Peer.decode_short_ids() against some data from
+        https://github.com/lightning/bolts/commit/313c0f290eb87e96dc8195cad0c891418a826c2c
+        """
+        # Test uncompressed encoding with three scids
+        encoded_uncompressed = bytes.fromhex("00" + "0000000000003043" + "00000000000778d6" + "000000000046e1c1")
+        result = Peer.decode_short_ids(encoded_uncompressed)
+        self.assertEqual(len(result), 3)
+        self.assertEqual(result[0], bytes.fromhex("0000000000003043"))  # 0x0x12355
+        self.assertEqual(result[1], bytes.fromhex("00000000000778d6"))  # 0x7x30934
+        self.assertEqual(result[2], bytes.fromhex("000000000046e1c1"))  # 0x70x57793
+
+        # Test empty list
+        encoded_empty = bytes.fromhex("00")
+        result = Peer.decode_short_ids(encoded_empty)
+        self.assertEqual(result, [])
+
+        # Test single scid
+        encoded_single = bytes.fromhex("00" + "000000000000008e")  # 0x0x142
+        result = Peer.decode_short_ids(encoded_single)
+        self.assertEqual(len(result), 1)
+        self.assertEqual(result[0], bytes.fromhex("000000000000008e"))
+
+        # test invalid size raises exception
+        encoded_invalid = bytes.fromhex("00" + "00" * 9)
+        with self.assertRaises(Exception) as ctx:
+            Peer.decode_short_ids(encoded_invalid)
+        self.assertIn("invalid size", str(ctx.exception))
+
+        # Test unsupported encoding raises exception (considering it even passes the length check)
+        encoded_unsupported = bytes.fromhex("01" + "00" * 8)  # 01 was zlib before removed
+        with self.assertRaises(Exception) as ctx:
+            Peer.decode_short_ids(encoded_unsupported)
+        self.assertIn("unexpected first byte", str(ctx.exception))
+
+
 class TestPeerDirect(TestPeer):
 
     def prepare_peers(