Merge pull request #66 from jkingsman/fix-three-byte-path-packets

Fix bad bitmask on three byte PATH packets

src/meshcore/reader.py

@@ -827,13 +827,13 @@ class MessageReader:
             res["pubkey_pre"] = dbuf.read(6).hex()
             opl = dbuf.read(1)[0]
             opl_hlen = ((opl & 0xc0) >> 6) + 1
-            opl = opl & 0xbf
+            opl = opl & 0x3f
             res["out_path_len"] = opl
             res["out_path_hash_len"] = opl_hlen
             res["out_path"] = dbuf.read(opl*opl_hlen).hex()
             ipl = dbuf.read(1)[0]
             ipl_hlen = ((ipl & 0xc0) >> 6) + 1
-            ipl = ipl & 0xbf
+            ipl = ipl & 0x3f
             res["in_path_len"] = ipl
             res["in_path_hash_len"] = ipl_hlen
             res["in_path"] = dbuf.read(ipl*ipl_hlen).hex()

tests/unit/test_path_discovery_response.py

@@ -0,0 +1,45 @@
+import pytest
+
+from meshcore.events import EventType
+from meshcore.reader import MessageReader
+
+pytestmark = pytest.mark.asyncio
+
+
+class MockDispatcher:
+    def __init__(self):
+        self.dispatched_events = []
+
+    async def dispatch(self, event):
+        self.dispatched_events.append(event)
+
+
+async def test_path_discovery_response_decodes_3byte_paths():
+    dispatcher = MockDispatcher()
+    reader = MessageReader(dispatcher)
+
+    packet = bytearray.fromhex(
+        "8d"  # PacketType.PATH_DISCOVERY_RESPONSE
+        "00"  # Reserved byte
+        "112233445566"  # 6-byte contact public-key prefix
+        "82"  # Outbound path descriptor: mode=2 (3-byte hops), hop_count=2
+        "a1a2a3b1b2b3"  # Outbound path bytes: 2 hops * 3 bytes each
+        "81"  # Inbound path descriptor: mode=2 (3-byte hops), hop_count=1
+        "c1c2c3"  # Inbound path bytes: 1 hop * 3 bytes
+    )
+
+    await reader.handle_rx(packet)
+
+    matching = [e for e in dispatcher.dispatched_events if e.type == EventType.PATH_RESPONSE]
+    assert len(matching) == 1
+
+    payload = matching[0].payload
+    assert payload["pubkey_pre"] == "112233445566"
+
+    assert payload["out_path_hash_len"] == 3
+    assert payload["out_path_len"] == 2
+    assert payload["out_path"] == "a1a2a3b1b2b3"
+
+    assert payload["in_path_hash_len"] == 3
+    assert payload["in_path_len"] == 1
+    assert payload["in_path"] == "c1c2c3"