(WIP) Namecoin: Refactor name_show to use gettransaction

This lets gettransaction do all the hard work regarding SPV verification.

TODO: Needs rebase once 5147, 5574, 5653, and 5660 merged upstream.

electrum_nmc/electrum/commands.py

@@ -1156,39 +1156,8 @@ async def name_show(self, identifier, stream_id=None):
 
  # The height is now verified to be safe.
 
- # (from verifier._request_proofs) if it's in the checkpoint region, we still might not have the header
- header = self.network.blockchain().read_header(height)
- if header is None:
- if height < constants.net.max_checkpoint():
- self.network.run_from_another_thread(self.network.request_chunk(height, None, stream_id=stream_id))
-
- # (from verifier._request_and_verify_single_proof)
- merkle = self.network.run_from_another_thread(self.network.get_merkle_for_transaction(txid, height, stream_id=stream_id))
- if height != merkle.get('block_height'):
- raise Exception('requested height {} differs from received height {} for txid {}'
- .format(height, merkle.get('block_height'), txid))
- pos = merkle.get('pos')
- merkle_branch = merkle.get('merkle')
- async def wait_for_header():
- # we need to wait if header sync/reorg is still ongoing, hence lock:
- async with self.network.bhi_lock:
- return self.network.blockchain().read_header(height)
- header = self.network.run_from_another_thread(wait_for_header())
- verify_tx_is_in_block(txid, merkle_branch, pos, header, height)
-
- # The txid is now verified to come from a safe height in the blockchain.
-
- if self.wallet and txid in self.wallet.db.transactions:
- tx = self.wallet.db.transactions[txid]
- else:
- raw = self.network.run_from_another_thread(self.network.get_transaction(txid, stream_id=stream_id))
- if raw:
- tx = Transaction(raw)
- else:
- raise Exception("Unknown transaction")
-
- if tx.txid() != txid:
- raise Exception("txid mismatch")
+ raw = self.gettransaction(txid, verify=True, height=height, stream_id=stream_id)['hex']
+ tx = Transaction(raw)
 
  # the tx is now verified to come from a safe height in the blockchain