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593 lines
26 KiB
593 lines
26 KiB
# -*- coding: utf-8 -*-
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#
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# Electrum - lightweight Bitcoin client
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# Copyright (C) 2018 The Electrum developers
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#
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# Permission is hereby granted, free of charge, to any person
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# obtaining a copy of this software and associated documentation files
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# (the "Software"), to deal in the Software without restriction,
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# including without limitation the rights to use, copy, modify, merge,
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# publish, distribute, sublicense, and/or sell copies of the Software,
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# and to permit persons to whom the Software is furnished to do so,
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# subject to the following conditions:
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#
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# The above copyright notice and this permission notice shall be
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# included in all copies or substantial portions of the Software.
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#
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# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
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# BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
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# ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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# CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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# SOFTWARE.
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import queue
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import os
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import json
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import threading
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from collections import namedtuple, defaultdict
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from typing import Sequence, List, Tuple, Optional, Dict, NamedTuple
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import binascii
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import base64
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import asyncio
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from . import constants
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from .util import PrintError, bh2u, profiler, get_headers_dir, bfh, is_ip_address, list_enabled_bits
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from .storage import JsonDB
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from .lnchannelverifier import LNChannelVerifier, verify_sig_for_channel_update
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from .crypto import Hash
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from . import ecc
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from .lnutil import LN_GLOBAL_FEATURES_KNOWN_SET, LNPeerAddr
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class UnknownEvenFeatureBits(Exception): pass
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class NotFoundChanAnnouncementForUpdate(Exception): pass
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class ChannelInfo(PrintError):
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def __init__(self, channel_announcement_payload):
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self.features_len = channel_announcement_payload['len']
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self.features = channel_announcement_payload['features']
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enabled_features = list_enabled_bits(int.from_bytes(self.features, "big"))
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for fbit in enabled_features:
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if (1 << fbit) not in LN_GLOBAL_FEATURES_KNOWN_SET and fbit % 2 == 0:
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raise UnknownEvenFeatureBits()
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self.channel_id = channel_announcement_payload['short_channel_id']
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self.node_id_1 = channel_announcement_payload['node_id_1']
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self.node_id_2 = channel_announcement_payload['node_id_2']
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assert type(self.node_id_1) is bytes
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assert type(self.node_id_2) is bytes
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assert list(sorted([self.node_id_1, self.node_id_2])) == [self.node_id_1, self.node_id_2]
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self.bitcoin_key_1 = channel_announcement_payload['bitcoin_key_1']
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self.bitcoin_key_2 = channel_announcement_payload['bitcoin_key_2']
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# this field does not get persisted
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self.msg_payload = channel_announcement_payload
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self.capacity_sat = None
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self.policy_node1 = None
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self.policy_node2 = None
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def to_json(self) -> dict:
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d = {}
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d['short_channel_id'] = bh2u(self.channel_id)
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d['node_id_1'] = bh2u(self.node_id_1)
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d['node_id_2'] = bh2u(self.node_id_2)
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d['len'] = bh2u(self.features_len)
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d['features'] = bh2u(self.features)
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d['bitcoin_key_1'] = bh2u(self.bitcoin_key_1)
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d['bitcoin_key_2'] = bh2u(self.bitcoin_key_2)
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d['policy_node1'] = self.policy_node1
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d['policy_node2'] = self.policy_node2
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d['capacity_sat'] = self.capacity_sat
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return d
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@classmethod
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def from_json(cls, d: dict):
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d2 = {}
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d2['short_channel_id'] = bfh(d['short_channel_id'])
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d2['node_id_1'] = bfh(d['node_id_1'])
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d2['node_id_2'] = bfh(d['node_id_2'])
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d2['len'] = bfh(d['len'])
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d2['features'] = bfh(d['features'])
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d2['bitcoin_key_1'] = bfh(d['bitcoin_key_1'])
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d2['bitcoin_key_2'] = bfh(d['bitcoin_key_2'])
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ci = ChannelInfo(d2)
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ci.capacity_sat = d['capacity_sat']
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ci.policy_node1 = ChannelInfoDirectedPolicy.from_json(d['policy_node1'])
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ci.policy_node2 = ChannelInfoDirectedPolicy.from_json(d['policy_node2'])
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return ci
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def set_capacity(self, capacity):
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self.capacity_sat = capacity
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def on_channel_update(self, msg_payload, trusted=False):
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assert self.channel_id == msg_payload['short_channel_id']
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flags = int.from_bytes(msg_payload['flags'], 'big')
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direction = flags & ChannelInfoDirectedPolicy.FLAG_DIRECTION
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new_policy = ChannelInfoDirectedPolicy(msg_payload)
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if direction == 0:
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old_policy = self.policy_node1
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node_id = self.node_id_1
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else:
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old_policy = self.policy_node2
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node_id = self.node_id_2
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if old_policy and old_policy.timestamp >= new_policy.timestamp:
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return # ignore
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if not trusted and not verify_sig_for_channel_update(msg_payload, node_id):
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return # ignore
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# save new policy
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if direction == 0:
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self.policy_node1 = new_policy
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else:
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self.policy_node2 = new_policy
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def get_policy_for_node(self, node_id: bytes) -> 'ChannelInfoDirectedPolicy':
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if node_id == self.node_id_1:
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return self.policy_node1
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elif node_id == self.node_id_2:
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return self.policy_node2
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else:
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raise Exception('node_id {} not in channel {}'.format(node_id, self.channel_id))
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class ChannelInfoDirectedPolicy:
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FLAG_DIRECTION = 1 << 0
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FLAG_DISABLE = 1 << 1
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def __init__(self, channel_update_payload):
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cltv_expiry_delta = channel_update_payload['cltv_expiry_delta']
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htlc_minimum_msat = channel_update_payload['htlc_minimum_msat']
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fee_base_msat = channel_update_payload['fee_base_msat']
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fee_proportional_millionths = channel_update_payload['fee_proportional_millionths']
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flags = channel_update_payload['flags']
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timestamp = channel_update_payload['timestamp']
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self.cltv_expiry_delta = int.from_bytes(cltv_expiry_delta, "big")
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self.htlc_minimum_msat = int.from_bytes(htlc_minimum_msat, "big")
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self.fee_base_msat = int.from_bytes(fee_base_msat, "big")
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self.fee_proportional_millionths = int.from_bytes(fee_proportional_millionths, "big")
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self.flags = int.from_bytes(flags, "big")
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self.timestamp = int.from_bytes(timestamp, "big")
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self.disabled = self.flags & self.FLAG_DISABLE
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def to_json(self) -> dict:
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d = {}
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d['cltv_expiry_delta'] = self.cltv_expiry_delta
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d['htlc_minimum_msat'] = self.htlc_minimum_msat
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d['fee_base_msat'] = self.fee_base_msat
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d['fee_proportional_millionths'] = self.fee_proportional_millionths
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d['flags'] = self.flags
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d['timestamp'] = self.timestamp
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return d
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@classmethod
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def from_json(cls, d: dict):
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if d is None: return None
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d2 = {}
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d2['cltv_expiry_delta'] = d['cltv_expiry_delta'].to_bytes(2, "big")
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d2['htlc_minimum_msat'] = d['htlc_minimum_msat'].to_bytes(8, "big")
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d2['fee_base_msat'] = d['fee_base_msat'].to_bytes(4, "big")
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d2['fee_proportional_millionths'] = d['fee_proportional_millionths'].to_bytes(4, "big")
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d2['flags'] = d['flags'].to_bytes(2, "big")
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d2['timestamp'] = d['timestamp'].to_bytes(4, "big")
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return ChannelInfoDirectedPolicy(d2)
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class NodeInfo(PrintError):
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def __init__(self, node_announcement_payload, addresses_already_parsed=False):
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self.pubkey = node_announcement_payload['node_id']
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self.features_len = node_announcement_payload['flen']
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self.features = node_announcement_payload['features']
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enabled_features = list_enabled_bits(int.from_bytes(self.features, "big"))
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for fbit in enabled_features:
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if (1 << fbit) not in LN_GLOBAL_FEATURES_KNOWN_SET and fbit % 2 == 0:
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raise UnknownEvenFeatureBits()
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if not addresses_already_parsed:
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self.addresses = self.parse_addresses_field(node_announcement_payload['addresses'])
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else:
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self.addresses = node_announcement_payload['addresses']
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self.alias = node_announcement_payload['alias'].rstrip(b'\x00')
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self.timestamp = int.from_bytes(node_announcement_payload['timestamp'], "big")
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@classmethod
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def parse_addresses_field(cls, addresses_field):
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buf = addresses_field
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def read(n):
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nonlocal buf
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data, buf = buf[0:n], buf[n:]
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return data
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addresses = []
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while buf:
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atype = ord(read(1))
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if atype == 0:
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pass
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elif atype == 1: # IPv4
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ipv4_addr = '.'.join(map(lambda x: '%d' % x, read(4)))
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port = int.from_bytes(read(2), 'big')
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if is_ip_address(ipv4_addr) and port != 0:
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addresses.append((ipv4_addr, port))
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elif atype == 2: # IPv6
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ipv6_addr = b':'.join([binascii.hexlify(read(2)) for i in range(8)])
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ipv6_addr = ipv6_addr.decode('ascii')
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port = int.from_bytes(read(2), 'big')
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if is_ip_address(ipv6_addr) and port != 0:
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addresses.append((ipv6_addr, port))
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elif atype == 3: # onion v2
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host = base64.b32encode(read(10)) + b'.onion'
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host = host.decode('ascii').lower()
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port = int.from_bytes(read(2), 'big')
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addresses.append((host, port))
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elif atype == 4: # onion v3
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host = base64.b32encode(read(35)) + b'.onion'
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host = host.decode('ascii').lower()
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port = int.from_bytes(read(2), 'big')
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addresses.append((host, port))
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else:
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# unknown address type
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# we don't know how long it is -> have to escape
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# if there are other addresses we could have parsed later, they are lost.
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break
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return addresses
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def to_json(self) -> dict:
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d = {}
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d['node_id'] = bh2u(self.pubkey)
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d['flen'] = bh2u(self.features_len)
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d['features'] = bh2u(self.features)
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d['addresses'] = self.addresses
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d['alias'] = bh2u(self.alias)
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d['timestamp'] = self.timestamp
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return d
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@classmethod
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def from_json(cls, d: dict):
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if d is None: return None
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d2 = {}
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d2['node_id'] = bfh(d['node_id'])
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d2['flen'] = bfh(d['flen'])
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d2['features'] = bfh(d['features'])
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d2['addresses'] = d['addresses']
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d2['alias'] = bfh(d['alias'])
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d2['timestamp'] = d['timestamp'].to_bytes(4, "big")
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return NodeInfo(d2, addresses_already_parsed=True)
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class ChannelDB(JsonDB):
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NUM_MAX_RECENT_PEERS = 20
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def __init__(self, network):
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self.network = network
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path = os.path.join(get_headers_dir(network.config), 'channel_db')
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JsonDB.__init__(self, path)
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self.lock = threading.RLock()
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self._id_to_channel_info = {} # type: Dict[bytes, ChannelInfo]
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self._channels_for_node = defaultdict(set) # node -> set(short_channel_id)
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self.nodes = {} # node_id -> NodeInfo
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self._recent_peers = []
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self._last_good_address = {} # node_id -> LNPeerAddr
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self.ca_verifier = LNChannelVerifier(network, self)
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self.load_data()
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def load_data(self):
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if os.path.exists(self.path):
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with open(self.path, "r", encoding='utf-8') as f:
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raw = f.read()
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self.data = json.loads(raw)
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# channels
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channel_infos = self.get('channel_infos', {})
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for short_channel_id, channel_info_d in channel_infos.items():
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channel_info = ChannelInfo.from_json(channel_info_d)
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short_channel_id = bfh(short_channel_id)
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self.add_verified_channel_info(short_channel_id, channel_info)
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# nodes
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node_infos = self.get('node_infos', {})
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for node_id, node_info_d in node_infos.items():
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node_info = NodeInfo.from_json(node_info_d)
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node_id = bfh(node_id)
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self.nodes[node_id] = node_info
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# recent peers
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recent_peers = self.get('recent_peers', {})
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for host, port, pubkey in recent_peers:
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peer = LNPeerAddr(str(host), int(port), bfh(pubkey))
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self._recent_peers.append(peer)
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# last good address
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last_good_addr = self.get('last_good_address', {})
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for node_id, host_and_port in last_good_addr.items():
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host, port = host_and_port
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self._last_good_address[bfh(node_id)] = LNPeerAddr(str(host), int(port), bfh(node_id))
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def save_data(self):
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with self.lock:
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# channels
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channel_infos = {}
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for short_channel_id, channel_info in self._id_to_channel_info.items():
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channel_infos[bh2u(short_channel_id)] = channel_info
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self.put('channel_infos', channel_infos)
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# nodes
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node_infos = {}
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for node_id, node_info in self.nodes.items():
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node_infos[bh2u(node_id)] = node_info
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self.put('node_infos', node_infos)
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# recent peers
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recent_peers = []
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for peer in self._recent_peers:
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recent_peers.append(
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[str(peer.host), int(peer.port), bh2u(peer.pubkey)])
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self.put('recent_peers', recent_peers)
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# last good address
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last_good_addr = {}
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for node_id, peer in self._last_good_address.items():
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last_good_addr[bh2u(node_id)] = [str(peer.host), int(peer.port)]
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self.put('last_good_address', last_good_addr)
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self.write()
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def __len__(self):
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# number of channels
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return len(self._id_to_channel_info)
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def get_channel_info(self, channel_id: bytes) -> Optional[ChannelInfo]:
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return self._id_to_channel_info.get(channel_id, None)
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def get_channels_for_node(self, node_id):
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"""Returns the set of channels that have node_id as one of the endpoints."""
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return self._channels_for_node[node_id]
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def add_verified_channel_info(self, short_channel_id: bytes, channel_info: ChannelInfo):
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with self.lock:
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self._id_to_channel_info[short_channel_id] = channel_info
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self._channels_for_node[channel_info.node_id_1].add(short_channel_id)
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self._channels_for_node[channel_info.node_id_2].add(short_channel_id)
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self.network.trigger_callback('ln_status')
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def get_recent_peers(self):
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with self.lock:
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return list(self._recent_peers)
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def add_recent_peer(self, peer: LNPeerAddr):
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with self.lock:
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# list is ordered
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if peer in self._recent_peers:
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self._recent_peers.remove(peer)
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self._recent_peers.insert(0, peer)
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self._recent_peers = self._recent_peers[:self.NUM_MAX_RECENT_PEERS]
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self._last_good_address[peer.pubkey] = peer
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def get_last_good_address(self, node_id: bytes) -> Optional[LNPeerAddr]:
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return self._last_good_address.get(node_id, None)
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def on_channel_announcement(self, msg_payload, trusted=False):
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short_channel_id = msg_payload['short_channel_id']
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if short_channel_id in self._id_to_channel_info:
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return
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if constants.net.rev_genesis_bytes() != msg_payload['chain_hash']:
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#self.print_error("ChanAnn has unexpected chain_hash {}".format(bh2u(msg_payload['chain_hash'])))
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return
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try:
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channel_info = ChannelInfo(msg_payload)
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except UnknownEvenFeatureBits:
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return
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if trusted:
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self.add_verified_channel_info(short_channel_id, channel_info)
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else:
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self.ca_verifier.add_new_channel_info(channel_info)
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def on_channel_update(self, msg_payload, trusted=False):
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short_channel_id = msg_payload['short_channel_id']
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if constants.net.rev_genesis_bytes() != msg_payload['chain_hash']:
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return
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# try finding channel in pending db
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channel_info = self.ca_verifier.get_pending_channel_info(short_channel_id)
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if channel_info is None:
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# try finding channel in verified db
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channel_info = self._id_to_channel_info.get(short_channel_id, None)
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if channel_info is None:
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self.print_error("could not find", short_channel_id)
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raise NotFoundChanAnnouncementForUpdate()
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channel_info.on_channel_update(msg_payload, trusted=trusted)
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def on_node_announcement(self, msg_payload):
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pubkey = msg_payload['node_id']
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signature = msg_payload['signature']
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h = Hash(msg_payload['raw'][66:])
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if not ecc.verify_signature(pubkey, signature, h):
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return
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old_node_info = self.nodes.get(pubkey, None)
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try:
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new_node_info = NodeInfo(msg_payload)
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except UnknownEvenFeatureBits:
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return
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# TODO if this message is for a new node, and if we have no associated
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# channels for this node, we should ignore the message and return here,
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# to mitigate DOS. but race condition: the channels we have for this
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# node, might be under verification in self.ca_verifier, what then?
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if old_node_info and old_node_info.timestamp >= new_node_info.timestamp:
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return # ignore
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self.nodes[pubkey] = new_node_info
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def remove_channel(self, short_channel_id):
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try:
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channel_info = self._id_to_channel_info[short_channel_id]
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except KeyError:
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self.print_error('cannot find channel {}'.format(short_channel_id))
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return
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self._id_to_channel_info.pop(short_channel_id, None)
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for node in (channel_info.node_id_1, channel_info.node_id_2):
|
|
try:
|
|
self._channels_for_node[node].remove(short_channel_id)
|
|
except KeyError:
|
|
pass
|
|
|
|
def print_graph(self, full_ids=False):
|
|
# used for debugging.
|
|
# FIXME there is a race here - iterables could change size from another thread
|
|
def other_node_id(node_id, channel_id):
|
|
channel_info = self._id_to_channel_info[channel_id]
|
|
if node_id == channel_info.node_id_1:
|
|
other = channel_info.node_id_2
|
|
else:
|
|
other = channel_info.node_id_1
|
|
return other if full_ids else other[-4:]
|
|
|
|
self.print_msg('node: {(channel, other_node), ...}')
|
|
for node_id, short_channel_ids in list(self._channels_for_node.items()):
|
|
short_channel_ids = {(bh2u(cid), bh2u(other_node_id(node_id, cid)))
|
|
for cid in short_channel_ids}
|
|
node_id = bh2u(node_id) if full_ids else bh2u(node_id[-4:])
|
|
self.print_msg('{}: {}'.format(node_id, short_channel_ids))
|
|
|
|
self.print_msg('channel: node1, node2, direction')
|
|
for short_channel_id, channel_info in list(self._id_to_channel_info.items()):
|
|
node1 = channel_info.node_id_1
|
|
node2 = channel_info.node_id_2
|
|
direction1 = channel_info.get_policy_for_node(node1) is not None
|
|
direction2 = channel_info.get_policy_for_node(node2) is not None
|
|
if direction1 and direction2:
|
|
direction = 'both'
|
|
elif direction1:
|
|
direction = 'forward'
|
|
elif direction2:
|
|
direction = 'backward'
|
|
else:
|
|
direction = 'none'
|
|
self.print_msg('{}: {}, {}, {}'
|
|
.format(bh2u(short_channel_id),
|
|
bh2u(node1) if full_ids else bh2u(node1[-4:]),
|
|
bh2u(node2) if full_ids else bh2u(node2[-4:]),
|
|
direction))
|
|
|
|
|
|
class RouteEdge(NamedTuple("RouteEdge", [('node_id', bytes),
|
|
('short_channel_id', bytes),
|
|
('fee_base_msat', int),
|
|
('fee_proportional_millionths', int),
|
|
('cltv_expiry_delta', int)])):
|
|
"""if you travel through short_channel_id, you will reach node_id"""
|
|
pass
|
|
|
|
|
|
class LNPathFinder(PrintError):
|
|
|
|
def __init__(self, channel_db):
|
|
self.channel_db = channel_db
|
|
self.blacklist = set()
|
|
|
|
def _edge_cost(self, short_channel_id: bytes, start_node: bytes, payment_amt_msat: int,
|
|
ignore_cltv=False) -> float:
|
|
"""Heuristic cost of going through a channel.
|
|
direction: 0 or 1. --- 0 means node_id_1 -> node_id_2
|
|
"""
|
|
channel_info = self.channel_db.get_channel_info(short_channel_id)
|
|
if channel_info is None:
|
|
return float('inf')
|
|
|
|
channel_policy = channel_info.get_policy_for_node(start_node)
|
|
if channel_policy is None: return float('inf')
|
|
if channel_policy.disabled: return float('inf')
|
|
cltv_expiry_delta = channel_policy.cltv_expiry_delta
|
|
htlc_minimum_msat = channel_policy.htlc_minimum_msat
|
|
fee_base_msat = channel_policy.fee_base_msat
|
|
fee_proportional_millionths = channel_policy.fee_proportional_millionths
|
|
if payment_amt_msat is not None:
|
|
if payment_amt_msat < htlc_minimum_msat:
|
|
return float('inf') # payment amount too little
|
|
if channel_info.capacity_sat is not None and \
|
|
payment_amt_msat // 1000 > channel_info.capacity_sat:
|
|
return float('inf') # payment amount too large
|
|
amt = payment_amt_msat or 50000 * 1000 # guess for typical payment amount
|
|
fee_msat = fee_base_msat + amt * fee_proportional_millionths / 1000000
|
|
# TODO revise
|
|
# paying 10 more satoshis ~ waiting one more block
|
|
fee_cost = fee_msat / 1000 / 10
|
|
cltv_cost = cltv_expiry_delta if not ignore_cltv else 0
|
|
return cltv_cost + fee_cost + 1
|
|
|
|
@profiler
|
|
def find_path_for_payment(self, from_node_id: bytes, to_node_id: bytes,
|
|
amount_msat: int=None) -> Sequence[Tuple[bytes, bytes]]:
|
|
"""Return a path between from_node_id and to_node_id.
|
|
|
|
Returns a list of (node_id, short_channel_id) representing a path.
|
|
To get from node ret[n][0] to ret[n+1][0], use channel ret[n+1][1];
|
|
i.e. an element reads as, "to get to node_id, travel through short_channel_id"
|
|
"""
|
|
if amount_msat is not None: assert type(amount_msat) is int
|
|
# TODO find multiple paths??
|
|
|
|
# run Dijkstra
|
|
distance_from_start = defaultdict(lambda: float('inf'))
|
|
distance_from_start[from_node_id] = 0
|
|
prev_node = {}
|
|
nodes_to_explore = queue.PriorityQueue()
|
|
nodes_to_explore.put((0, from_node_id))
|
|
|
|
while nodes_to_explore.qsize() > 0:
|
|
dist_to_cur_node, cur_node = nodes_to_explore.get()
|
|
if cur_node == to_node_id:
|
|
break
|
|
if dist_to_cur_node != distance_from_start[cur_node]:
|
|
# queue.PriorityQueue does not implement decrease_priority,
|
|
# so instead of decreasing priorities, we add items again into the queue.
|
|
# so there are duplicates in the queue, that we discard now:
|
|
continue
|
|
for edge_channel_id in self.channel_db.get_channels_for_node(cur_node):
|
|
if edge_channel_id in self.blacklist: continue
|
|
channel_info = self.channel_db.get_channel_info(edge_channel_id)
|
|
node1, node2 = channel_info.node_id_1, channel_info.node_id_2
|
|
neighbour = node2 if node1 == cur_node else node1
|
|
ignore_cltv_delta_in_edge_cost = cur_node == from_node_id
|
|
edge_cost = self._edge_cost(edge_channel_id, cur_node, amount_msat,
|
|
ignore_cltv=ignore_cltv_delta_in_edge_cost)
|
|
alt_dist_to_neighbour = distance_from_start[cur_node] + edge_cost
|
|
if alt_dist_to_neighbour < distance_from_start[neighbour]:
|
|
distance_from_start[neighbour] = alt_dist_to_neighbour
|
|
prev_node[neighbour] = cur_node, edge_channel_id
|
|
nodes_to_explore.put((alt_dist_to_neighbour, neighbour))
|
|
else:
|
|
return None # no path found
|
|
|
|
# backtrack from end to start
|
|
cur_node = to_node_id
|
|
path = []
|
|
while cur_node != from_node_id:
|
|
prev_node_id, edge_taken = prev_node[cur_node]
|
|
path += [(cur_node, edge_taken)]
|
|
cur_node = prev_node_id
|
|
path.reverse()
|
|
return path
|
|
|
|
def create_route_from_path(self, path, from_node_id: bytes) -> List[RouteEdge]:
|
|
assert type(from_node_id) is bytes
|
|
if path is None:
|
|
raise Exception('cannot create route from None path')
|
|
route = []
|
|
prev_node_id = from_node_id
|
|
for node_id, short_channel_id in path:
|
|
channel_info = self.channel_db.get_channel_info(short_channel_id)
|
|
if channel_info is None:
|
|
raise Exception('cannot find channel info for short_channel_id: {}'.format(bh2u(short_channel_id)))
|
|
channel_policy = channel_info.get_policy_for_node(prev_node_id)
|
|
if channel_policy is None:
|
|
raise Exception('cannot find channel policy for short_channel_id: {}'.format(bh2u(short_channel_id)))
|
|
route.append(RouteEdge(node_id,
|
|
short_channel_id,
|
|
channel_policy.fee_base_msat,
|
|
channel_policy.fee_proportional_millionths,
|
|
channel_policy.cltv_expiry_delta))
|
|
prev_node_id = node_id
|
|
return route
|
|
|