Warn user if imported key has derivation path different from xpub's depth

Author: roshii

src/cryptoadvance/specter/key.py

@@ -1,8 +1,10 @@
+import logging
 from collections import OrderedDict
 from binascii import hexlify
 from embit import base58
 from .util.xpub import get_xpub_fingerprint
 
+logger = logging.getLogger(__name__)
 
 purposes = OrderedDict(
     {
@@ -135,9 +137,16 @@ def parse_xpub(cls, xpub, purpose=""):
                     elif derivation_path[4] == "2h":
                         key_type = "wsh"
 
+        # warn user if imported key has derivation path different from xpub's depth
+        depth = xpub_bytes[4]
+        if derivation != "" and depth != len(derivation_path):
+            logger.warning(
+                f"xpup has a depth of {depth} while derivation path "
+                f"indicates the key is {len(derivation_path)} levels deep"
+            )
+
         # infer fingerprint and derivation if depth == 0 or depth == 1
         xpub_bytes = base58.decode_check(xpub)
-        depth = xpub_bytes[4]
         if depth == 0:
             fingerprint = hexlify(get_xpub_fingerprint(xpub)).decode()
             derivation = "m"