Namecoin: Fix Merkle exception handling in Buy Names tab

electrum_nmc/electrum/gui/qt/main_window.py

@@ -54,6 +54,7 @@
 from electrum.bitcoin import COIN, is_address
 from electrum.plugin import run_hook, BasePlugin
 from electrum.i18n import _
+from electrum.merkle import MerkleVerificationFailure
 from electrum.names import format_name_identifier, get_wallet_name_count, name_new_mature_in
 from electrum.util import (format_time,
                            UserCancelled, profiler,
@@ -3470,6 +3471,12 @@ def check_name_availability(self):
             msg = repr(e)
             self.show_error(msg)
             return
+        except MerkleVerificationFailure:
+            # Merkle proof from ElectrumX was invalid
+            self.buy_names_register_button.hide()
+            self.buy_names_buy_button.hide()
+            self.buy_names_status_label.setText(_("Merkle verification failure while checking name availability.  If this persists, try switching servers."))
+            return
 
         if chain_syncing:
             self.buy_names_register_button.hide()

electrum_nmc/electrum/interface.py

@@ -57,7 +57,7 @@
 from . import blockchain
 from .blockchain import Blockchain, HeaderChunk, HEADER_SIZE
 from . import bitcoin
-from .merkle import hash_merkle_root
+from .merkle import hash_merkle_root, MerkleRootMismatch
 from . import constants
 from .i18n import _
 from .logging import Logger
@@ -253,6 +253,7 @@ class ErrorSSLCertFingerprintMismatch(Exception): pass
 class InvalidOptionCombination(Exception): pass
 class ConnectError(NetworkException): pass
 
+class CheckpointMerkleRootMismatch(MerkleRootMismatch): pass
 
 class _RSClient(RSClient):
     async def create_connection(self):
@@ -784,12 +785,12 @@ def validate_checkpoint_result(self, received_merkle_root, merkle_branch, header
         expected_merkle_root = constants.net.CHECKPOINTS['merkle_root']
 
         if received_merkle_root != expected_merkle_root:
-            raise Exception("Sent unexpected merkle root, expected: {}, got: {}".format(expected_merkle_root, received_merkle_root))
+            raise CheckpointMerkleRootMismatch("Sent unexpected merkle root, expected: {}, got: {}".format(expected_merkle_root, received_merkle_root))
 
         header_hash = hash_encode(sha256d(bfh(header)))
         proven_merkle_root = hash_merkle_root(merkle_branch, header_hash, header_height, reject_valid_tx=False)
         if proven_merkle_root != expected_merkle_root:
-            raise Exception("Sent incorrect merkle branch, expected: {}, proved: {}".format(constants.net.CHECKPOINTS['merkle_root'], proven_merkle_root))
+            raise CheckpointMerkleRootMismatch("Sent incorrect merkle branch, expected: {}, proved: {}".format(constants.net.CHECKPOINTS['merkle_root'], proven_merkle_root))
 
     def is_main_server(self) -> bool:
         return self.network.default_server == self.server

electrum_nmc/electrum/merkle.py

@@ -30,6 +30,7 @@
 
 class MerkleVerificationFailure(Exception): pass
 class InnerNodeOfSpvProofIsValidTx(MerkleVerificationFailure): pass
+class MerkleRootMismatch(MerkleVerificationFailure): pass
 
 def hash_merkle_root(merkle_branch: Sequence[str], tx_hash: str, leaf_pos_in_tree: int, reject_valid_tx: bool=True):
     """Return calculated merkle root."""

electrum_nmc/electrum/verifier.py

@@ -34,7 +34,7 @@
 from .blockchain import hash_header
 from .interface import GracefulDisconnect
 from .network import UntrustedServerReturnedError
-from .merkle import hash_merkle_root, MerkleVerificationFailure
+from .merkle import hash_merkle_root, MerkleVerificationFailure, MerkleRootMismatch
 from . import constants
 
 if TYPE_CHECKING:
@@ -43,7 +43,6 @@
 
 
 class MissingBlockHeader(MerkleVerificationFailure): pass
-class MerkleRootMismatch(MerkleVerificationFailure): pass
 
 
 class SPV(NetworkJobOnDefaultServer):