Fix path length calculation and hash mode handling in MessageHandler

- Improved error handling for `out_path_hash_mode` and `out_path_len` to ensure proper type conversion and validation.
- Added logic to derive `out_path_len` from `out_path` when it is missing, enhancing robustness against incomplete data.
- Updated tests to verify correct behavior when `out_path_hash_mode` is provided as a string and `out_path_len` is absent.

modules/message_handler.py

@@ -2922,12 +2922,47 @@ class MessageHandler:
         meshcore update_contact uses out_path_len | (out_path_hash_mode << 6); hash_mode -1 with
         non-negative hop count produces a negative int and OverflowError on unsigned to_bytes.
         """
-        if contact_data.get('out_path_hash_mode', 0) != -1:
+        try:
+            hash_mode = int(contact_data.get('out_path_hash_mode', 0))
+        except (TypeError, ValueError):
             return
-        opl = contact_data.get('out_path_len')
-        if opl is None or opl < 0 or opl == -1:
+        if hash_mode != -1:
             return
-        bph = contact_data.get('out_bytes_per_hop', 1) or 1
+
+        opl: Optional[int]
+        raw_opl = contact_data.get('out_path_len')
+        try:
+            opl = None if raw_opl is None else int(raw_opl)
+        except (TypeError, ValueError):
+            opl = None
+
+        bph_raw = contact_data.get('out_bytes_per_hop', 1) or 1
+        try:
+            bph = int(bph_raw)
+        except (TypeError, ValueError):
+            bph = 1
+        if bph not in (1, 2, 3):
+            bph = 1
+
+        # Some NEW_CONTACT payloads omit out_path_len but include out_path + bytes_per_hop.
+        # Derive hop count here so meshcore doesn't combine a non-flood path with hash_mode=-1.
+        if opl is None:
+            out_path_hex = contact_data.get('out_path') or ''
+            if not isinstance(out_path_hex, str) or not out_path_hex:
+                return
+            if (len(out_path_hex) % 2) != 0:
+                return
+            path_bytes = len(out_path_hex) // 2
+            if path_bytes <= 0:
+                return
+            if (path_bytes % bph) == 0:
+                opl = path_bytes // bph
+            else:
+                opl = path_bytes
+
+        if opl < 0 or opl == -1:
+            return
+
         try:
             pb = encode_path_len_byte(opl, bph)
         except ValueError:

tests/test_message_handler_contact_path.py

@@ -95,6 +95,17 @@ class TestEnsureContactMeshcorePathEncoding:
         assert c["out_path_len"] == 3
         assert (c["out_path_len"] | (c["out_path_hash_mode"] << 6)) == 0x43
 
+    def test_fixes_when_hash_mode_is_string_and_out_path_len_missing(self, message_handler):
+        c = {
+            "out_path_hash_mode": "-1",
+            "out_path": "01020304",
+            "out_bytes_per_hop": 1,
+        }
+        message_handler._ensure_contact_meshcore_path_encoding(c)
+        assert c["out_path_hash_mode"] == 0
+        assert c["out_path_len"] == 4
+        assert (c["out_path_len"] | (c["out_path_hash_mode"] << 6)) == 0x04
+
 
 class TestHandleNewContactAddContact:
     """handle_new_contact + mocked add_contact: path fields match wire encoding (no OverflowError)."""