follow-up prev

electrum/lnbase.py

@@ -23,7 +23,7 @@ from .ecc import sig_string_from_r_and_s, get_r_and_s_from_sig_string
 from . import constants
 from .util import PrintError, bh2u, print_error, bfh, log_exceptions, list_enabled_bits, ignore_exceptions
 from .transaction import Transaction, TxOutput
-from .lnonion import new_onion_packet, OnionHopsDataSingle, OnionPerHop, decode_onion_error, OnionFailureCode
+from .lnonion import new_onion_packet, decode_onion_error, OnionFailureCode, calc_hops_data_for_payment
 from .lnaddr import lndecode
 from .lnchan import Channel, RevokeAndAck, htlcsum
 from .lnutil import (Outpoint, LocalConfig, ChannelConfig,
@@ -927,33 +927,14 @@ class Peer(PrintError):
         await self.receive_commitment(chan)
         self.revoke(chan)
 
-    def calc_hops_data_for_payment(self, route: List[RouteEdge], amount_msat: int, min_final_cltv_expiry: int):
-        """Returns the hops_data to be used for constructing an onion packet,
-        and the amount_msat and cltv to be used on our immediate channel.
-        """
-        amt = amount_msat
-        height = self.network.get_local_height()
-        cltv = height + min_final_cltv_expiry
-        hops_data = [OnionHopsDataSingle(OnionPerHop(b"\x00" * 8,
-                                                     amt.to_bytes(8, "big"),
-                                                     cltv.to_bytes(4, "big")))]
-        for route_edge in reversed(route[1:]):
-            hops_data += [OnionHopsDataSingle(OnionPerHop(route_edge.short_channel_id,
-                                                          amt.to_bytes(8, "big"),
-                                                          cltv.to_bytes(4, "big")))]
-            amt += route_edge.fee_for_edge(amt)
-            cltv += route_edge.cltv_expiry_delta
-        hops_data.reverse()
-        return hops_data, amt, cltv
-
     async def pay(self, route: List[RouteEdge], chan, amount_msat, payment_hash, min_final_cltv_expiry):
         assert chan.get_state() == "OPEN", chan.get_state()
         assert amount_msat > 0, "amount_msat is not greater zero"
         # create onion packet
-        hops_data, amount_msat, cltv = self.calc_hops_data_for_payment(route, amount_msat, min_final_cltv_expiry)
-        associated_data = payment_hash
+        final_cltv = self.network.get_local_height() + min_final_cltv_expiry
+        hops_data, amount_msat, cltv = calc_hops_data_for_payment(route, amount_msat, final_cltv)
         secret_key = os.urandom(32)
-        onion = new_onion_packet([x.node_id for x in route], secret_key, hops_data, associated_data)
+        onion = new_onion_packet([x.node_id for x in route], secret_key, hops_data, associated_data=payment_hash)
         chan.check_can_pay(amount_msat)
         # create htlc
         htlc = {'amount_msat':amount_msat, 'payment_hash':payment_hash, 'cltv_expiry':cltv}

electrum/lnonion.py

@@ -26,7 +26,7 @@
 import hashlib
 import hmac
 from collections import namedtuple
-from typing import Sequence
+from typing import Sequence, List, Tuple
 from enum import IntEnum, IntFlag
 
 from cryptography.hazmat.primitives.ciphers import Cipher, algorithms
@@ -36,6 +36,7 @@ from . import ecc
 from .crypto import sha256
 from .util import bh2u, profiler, xor_bytes, bfh
 from .lnutil import get_ecdh
+from .lnrouter import RouteEdge
 
 
 NUM_MAX_HOPS_IN_PATH = 20
@@ -188,6 +189,26 @@ def new_onion_packet(payment_path_pubkeys: Sequence[bytes], session_key: bytes,
         hmac=next_hmac)
 
 
+def calc_hops_data_for_payment(route: List[RouteEdge], amount_msat: int, final_cltv: int) \
+        -> Tuple[List[OnionHopsDataSingle], int, int]:
+    """Returns the hops_data to be used for constructing an onion packet,
+    and the amount_msat and cltv to be used on our immediate channel.
+    """
+    amt = amount_msat
+    cltv = final_cltv
+    hops_data = [OnionHopsDataSingle(OnionPerHop(b"\x00" * 8,
+                                                 amt.to_bytes(8, "big"),
+                                                 cltv.to_bytes(4, "big")))]
+    for route_edge in reversed(route[1:]):
+        hops_data += [OnionHopsDataSingle(OnionPerHop(route_edge.short_channel_id,
+                                                      amt.to_bytes(8, "big"),
+                                                      cltv.to_bytes(4, "big")))]
+        amt += route_edge.fee_for_edge(amt)
+        cltv += route_edge.cltv_expiry_delta
+    hops_data.reverse()
+    return hops_data, amt, cltv
+
+
 def generate_filler(key_type: bytes, num_hops: int, hop_size: int,
                     shared_secrets: Sequence[bytes]) -> bytes:
     filler_size = (NUM_MAX_HOPS_IN_PATH + 1) * hop_size