lnsweep: rm code dupe: 2nd stage htlc tx out vs ctx to_local addr reuse

electrum/lnsweep.py

@@ -61,7 +61,7 @@ def create_sweeptxs_for_watchtower(chan: 'Channel', ctx: Transaction, per_commit
             sweep_address=sweep_address,
             ctx=ctx,
             output_idx=output_idx,
-            witness_script=witness_script,
+            witness_script=bfh(witness_script),
             privkey=other_revocation_privkey,
             is_revocation=True,
             config=chan.lnworker.config)
@@ -80,7 +80,6 @@ def create_sweeptx_for_htlc(*, htlc: 'UpdateAddHtlc', htlc_direction: Direction,
             htlc=htlc,
             ctx_output_idx=ctx_output_idx)
         return create_sweeptx_that_spends_htlctx_that_spends_htlc_in_ctx(
-            to_self_delay=0,
             htlc_tx=htlc_tx,
             htlctx_witness_script=htlc_tx_witness_script,
             sweep_address=sweep_address,
@@ -129,7 +128,7 @@ def create_sweeptx_for_their_revoked_ctx(
             sweep_address=sweep_address,
             ctx=ctx,
             output_idx=output_idx,
-            witness_script=witness_script,
+            witness_script=bfh(witness_script),
             privkey=other_revocation_privkey,
             is_revocation=True,
             config=chan.lnworker.config)
@@ -165,11 +164,10 @@ def create_sweeptx_for_their_revoked_htlc(
     # check that htlc_tx is a htlc
     if htlc_tx.outputs()[0].address != htlc_address:
         return
-    gen_tx = lambda: create_sweeptx_ctx_to_local(
+    gen_tx = lambda: create_sweeptx_that_spends_htlctx_that_spends_htlc_in_ctx(
         sweep_address=sweep_address,
-        ctx=htlc_tx,
-        output_idx=0,
-        witness_script=witness_script,
+        htlc_tx=htlc_tx,
+        htlctx_witness_script=bfh(witness_script),
         privkey=other_revocation_privkey,
         is_revocation=True,
         config=chan.lnworker.config)
@@ -227,7 +225,7 @@ def create_sweeptxs_for_our_ctx(
             sweep_address=sweep_address,
             ctx=ctx,
             output_idx=output_idx,
-            witness_script=to_local_witness_script,
+            witness_script=bfh(to_local_witness_script),
             privkey=our_localdelayed_privkey.get_secret_bytes(),
             is_revocation=False,
             to_self_delay=to_self_delay,
@@ -527,9 +525,9 @@ def create_sweeptx_their_ctx_to_remote(
 
 
 def create_sweeptx_ctx_to_local(
-        *, sweep_address: str, ctx: Transaction, output_idx: int, witness_script: str,
+        *, sweep_address: str, ctx: Transaction, output_idx: int, witness_script: bytes,
         privkey: bytes, is_revocation: bool, config: SimpleConfig,
-        to_self_delay: int=None) -> Optional[PartialTransaction]:
+        to_self_delay: int = None) -> Optional[PartialTransaction]:
     """Create a txn that sweeps the 'to_local' output of a commitment
     transaction into our wallet.
 
@@ -541,7 +539,7 @@ def create_sweeptx_ctx_to_local(
     txin = PartialTxInput(prevout=prevout)
     txin._trusted_value_sats = val
     txin.script_sig = b''
-    txin.witness_script = bfh(witness_script)
+    txin.witness_script = witness_script
     sweep_inputs = [txin]
     if not is_revocation:
         assert isinstance(to_self_delay, int)
@@ -561,26 +559,20 @@ def create_sweeptx_ctx_to_local(
 
 def create_sweeptx_that_spends_htlctx_that_spends_htlc_in_ctx(
         *, htlc_tx: Transaction, htlctx_witness_script: bytes, sweep_address: str,
-        privkey: bytes, is_revocation: bool, to_self_delay: int,
+        privkey: bytes, is_revocation: bool, to_self_delay: int = None,
         config: SimpleConfig) -> Optional[PartialTransaction]:
-    val = htlc_tx.outputs()[0].value
-    prevout = TxOutpoint(txid=bfh(htlc_tx.txid()), out_idx=0)
-    txin = PartialTxInput(prevout=prevout)
-    txin._trusted_value_sats = val
-    txin.script_sig = b''
-    txin.witness_script = htlctx_witness_script
-    sweep_inputs = [txin]
-    if not is_revocation:
-        assert isinstance(to_self_delay, int)
-        sweep_inputs[0].nsequence = to_self_delay
-    tx_size_bytes = 200  # TODO
-    fee = config.estimate_fee(tx_size_bytes, allow_fallback_to_static_rates=True)
-    outvalue = val - fee
-    if outvalue <= dust_threshold(): return None
-    sweep_outputs = [PartialTxOutput.from_address_and_value(sweep_address, outvalue)]
-    tx = PartialTransaction.from_io(sweep_inputs, sweep_outputs, version=2)
-    sig = bfh(tx.sign_txin(0, privkey))
-    witness = construct_witness([sig, int(is_revocation), htlctx_witness_script])
-    tx.inputs()[0].witness = bfh(witness)
-    assert tx.is_complete()
-    return tx
+    """Create a txn that sweeps the output of a second stage htlc tx
+    (i.e. sweeps from an HTLC-Timeout or an HTLC-Success tx).
+    """
+    # note: this is the same as sweeping the to_local output of the ctx,
+    #       as these are the same script (address-reuse).
+    return create_sweeptx_ctx_to_local(
+        sweep_address=sweep_address,
+        ctx=htlc_tx,
+        output_idx=0,
+        witness_script=htlctx_witness_script,
+        privkey=privkey,
+        is_revocation=is_revocation,
+        to_self_delay=to_self_delay,
+        config=config,
+    )

electrum/lnutil.py

@@ -509,19 +509,11 @@ def derive_blinded_privkey(basepoint_secret: bytes, per_commitment_secret: bytes
 def make_htlc_tx_output(amount_msat, local_feerate, revocationpubkey, local_delayedpubkey, success, to_self_delay):
     assert type(amount_msat) is int
     assert type(local_feerate) is int
-    assert type(revocationpubkey) is bytes
-    assert type(local_delayedpubkey) is bytes
-    script = bfh(construct_script([
-        opcodes.OP_IF,
-        revocationpubkey,
-        opcodes.OP_ELSE,
-        to_self_delay,
-        opcodes.OP_CHECKSEQUENCEVERIFY,
-        opcodes.OP_DROP,
-        local_delayedpubkey,
-        opcodes.OP_ENDIF,
-        opcodes.OP_CHECKSIG,
-    ]))
+    script = make_commitment_output_to_local_witness_script(
+        revocation_pubkey=revocationpubkey,
+        to_self_delay=to_self_delay,
+        delayed_pubkey=local_delayedpubkey,
+    )
 
     p2wsh = bitcoin.redeem_script_to_address('p2wsh', bh2u(script))
     weight = HTLC_SUCCESS_WEIGHT if success else HTLC_TIMEOUT_WEIGHT
@@ -896,7 +888,11 @@ def make_commitment(
     return tx
 
 def make_commitment_output_to_local_witness_script(
-        revocation_pubkey: bytes, to_self_delay: int, delayed_pubkey: bytes) -> bytes:
+        revocation_pubkey: bytes, to_self_delay: int, delayed_pubkey: bytes,
+) -> bytes:
+    assert type(revocation_pubkey) is bytes
+    assert type(to_self_delay) is int
+    assert type(delayed_pubkey) is bytes
     script = bfh(construct_script([
         opcodes.OP_IF,
         revocation_pubkey,