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466 lines
15 KiB
466 lines
15 KiB
from .bech32 import bech32_encode, bech32_decode, CHARSET
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from binascii import hexlify, unhexlify
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from decimal import Decimal
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from io import BufferedReader, BytesIO
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import base58
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import bitstring
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import hashlib
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import re
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import coincurve
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import time
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import struct
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# BOLT #11:
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#
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# A writer MUST encode `amount` as a positive decimal integer with no
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# leading zeroes, SHOULD use the shortest representation possible.
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def shorten_amount(amount):
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""" Given an amount in bitcoin, shorten it
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"""
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# Convert to pico initially
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amount = int(amount * 10**12)
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units = ['p', 'n', 'u', 'm', '']
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for unit in units:
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if amount % 1000 == 0:
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amount //= 1000
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else:
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break
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return str(amount) + unit
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def unshorten_amount(amount):
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""" Given a shortened amount, convert it into a decimal
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"""
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# BOLT #11:
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# The following `multiplier` letters are defined:
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#
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# * `m` (milli): multiply by 0.001
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# * `u` (micro): multiply by 0.000001
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# * `n` (nano): multiply by 0.000000001
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# * `p` (pico): multiply by 0.000000000001
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units = {
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'p': 10**12,
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'n': 10**9,
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'u': 10**6,
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'm': 10**3,
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}
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unit = str(amount)[-1]
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# BOLT #11:
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# A reader SHOULD fail if `amount` contains a non-digit, or is followed by
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# anything except a `multiplier` in the table above.
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if not re.fullmatch(r'\d+[pnum]?', str(amount)):
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raise ValueError("Invalid amount '{}'".format(amount))
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if unit in units.keys():
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return Decimal(amount[:-1]) / units[unit]
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else:
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return Decimal(amount)
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# Bech32 spits out array of 5-bit values. Shim here.
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def u5_to_bitarray(arr: bytes):
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ret = bitstring.BitArray()
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for a in arr:
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ret += bitstring.pack("uint:5", a)
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return ret
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def bitarray_to_u5(barr) -> bytes:
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assert barr.len % 5 == 0
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ret = []
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s = bitstring.ConstBitStream(barr)
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while s.pos != s.len:
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ret.append(s.read(5).uint)
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return bytes(ret)
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def encode_fallback(fallback, currency):
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""" Encode all supported fallback addresses.
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"""
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if currency == 'bc' or currency == 'tb':
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fbhrp, witness = bech32_decode(fallback)
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if fbhrp:
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if fbhrp != currency:
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raise ValueError("Not a bech32 address for this currency")
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wver = witness[0]
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if wver > 16:
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raise ValueError("Invalid witness version {}".format(witness[0]))
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wprog = u5_to_bitarray(witness[1:])
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else:
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addr = base58.b58decode_check(fallback)
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if is_p2pkh(currency, addr[0]):
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wver = 17
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elif is_p2sh(currency, addr[0]):
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wver = 18
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else:
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raise ValueError("Unknown address type for {}".format(currency))
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wprog = addr[1:]
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return tagged('f', bitstring.pack("uint:5", wver) + wprog)
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else:
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raise NotImplementedError("Support for currency {} not implemented".format(currency))
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def parse_fallback(fallback, currency):
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if currency == 'bc' or currency == 'tb':
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wver = fallback[0:5].uint
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if wver == 17:
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addr = base58.b58encode_check(bytes([base58_prefix_map[currency][0]])
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+ fallback[5:].tobytes())
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elif wver == 18:
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addr = base58.b58encode_check(bytes([base58_prefix_map[currency][1]])
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+ fallback[5:].tobytes())
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elif wver <= 16:
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addr = bech32_encode(currency, bitarray_to_u5(fallback))
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else:
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return None
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else:
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addr = fallback.tobytes()
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return addr
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# Map of classical and witness address prefixes
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base58_prefix_map = {
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'bc': (0, 5),
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'tb': (111, 196)
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}
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def is_p2pkh(currency, prefix):
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return prefix == base58_prefix_map[currency][0]
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def is_p2sh(currency, prefix):
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return prefix == base58_prefix_map[currency][1]
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# Tagged field containing BitArray
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def tagged(char, l):
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# Tagged fields need to be zero-padded to 5 bits.
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while l.len % 5 != 0:
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l.append('0b0')
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return bitstring.pack("uint:5, uint:5, uint:5",
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CHARSET.find(char),
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(l.len / 5) / 32, (l.len / 5) % 32) + l
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# Tagged field containing bytes
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def tagged_bytes(char, l):
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return tagged(char, bitstring.BitArray(l))
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# Discard trailing bits, convert to bytes.
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def trim_to_bytes(barr):
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# Adds a byte if necessary.
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b = barr.tobytes()
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if barr.len % 8 != 0:
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return b[:-1]
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return b
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# Try to pull out tagged data: returns tag, tagged data and remainder.
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def pull_tagged(stream):
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tag = stream.read(5).uint
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length = stream.read(5).uint * 32 + stream.read(5).uint
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return (CHARSET[tag], stream.read(length * 5), stream)
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class Invoice(object):
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def __init__(self, paymenthash=None, amount=None, currency='bc', tags=None, date=None):
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self.date = int(time.time()) if not date else int(date)
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self.tags = [] if not tags else tags
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self.unknown_tags = []
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self.paymenthash = paymenthash
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self.signature = None
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self.pubkey = None
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self.currency = currency
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self.amount = amount
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self.min_final_cltv_expiry = None
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self.route_hints = None
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def __str__(self):
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return "Invoice[{}, amount={}{} tags=[{}]]".format(
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hexlify(self.pubkey.format()).decode('utf-8'),
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self.amount, self.currency,
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", ".join([k + '=' + str(v) for k, v in self.tags])
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)
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@property
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def hexpubkey(self):
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return hexlify(self.pubkey.format()).decode('ASCII')
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@property
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def hexpaymenthash(self):
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return hexlify(self.paymenthash).decode('ASCII')
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def _get_tagged(self, tag):
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return [t[1] for t in self.tags + self.unknown_tags if t[0] == tag]
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@property
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def featurebits(self):
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features = self._get_tagged('9')
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assert(len(features) <= 1)
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if features == []:
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return 0
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else:
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return features[0]
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def encode(self, privkey):
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if self.amount:
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amount = Decimal(str(self.amount))
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# We can only send down to millisatoshi.
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if amount * 10**12 % 10:
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raise ValueError("Cannot encode {}: too many decimal places".format(
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self.amount))
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amount = self.currency + shorten_amount(amount)
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else:
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amount = self.currency if self.currency else ''
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hrp = 'ln' + amount
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# Start with the timestamp
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data = bitstring.pack('uint:35', self.date)
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# Payment hash
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data += tagged_bytes('p', self.paymenthash)
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tags_set = set()
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if self.route_hints is not None:
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for rh in self.route_hints.route_hints:
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data += tagged_bytes('r', rh.to_bytes())
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for k, v in self.tags:
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# BOLT #11:
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#
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# A writer MUST NOT include more than one `d`, `h`, `n` or `x` fields,
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if k in ('d', 'h', 'n', 'x'):
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if k in tags_set:
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raise ValueError("Duplicate '{}' tag".format(k))
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if k == 'r':
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pubkey, channel, fee, cltv = v
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route = bitstring.BitArray(pubkey) + bitstring.BitArray(channel) + bitstring.pack('intbe:64', fee) + bitstring.pack('intbe:16', cltv)
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data += tagged('r', route)
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elif k == 'f':
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data += encode_fallback(v, self.currency)
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elif k == 'd':
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data += tagged_bytes('d', v.encode())
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elif k == 'x':
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# Get minimal length by trimming leading 5 bits at a time.
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expirybits = bitstring.pack('intbe:64', v)[4:64]
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while expirybits.startswith('0b00000'):
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expirybits = expirybits[5:]
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data += tagged('x', expirybits)
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elif k == 'h':
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data += tagged_bytes('h', hashlib.sha256(v.encode('utf-8')).digest())
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elif k == 'n':
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data += tagged_bytes('n', v)
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else:
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# FIXME: Support unknown tags?
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raise ValueError("Unknown tag {}".format(k))
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tags_set.add(k)
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# BOLT #11:
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#
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# A writer MUST include either a `d` or `h` field, and MUST NOT include
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# both.
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if 'd' in tags_set and 'h' in tags_set:
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raise ValueError("Cannot include both 'd' and 'h'")
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if 'd' not in tags_set and 'h' not in tags_set:
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raise ValueError("Must include either 'd' or 'h'")
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# We actually sign the hrp, then data (padded to 8 bits with zeroes).
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privkey = coincurve.PrivateKey(secret=bytes(unhexlify(privkey)))
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data += privkey.sign_recoverable(bytearray([ord(c) for c in hrp]) + data.tobytes())
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return bech32_encode(hrp, bitarray_to_u5(data))
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@classmethod
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def decode(cls, b):
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hrp, data = bech32_decode(b)
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if not hrp:
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raise ValueError("Bad bech32 checksum")
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# BOLT #11:
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#
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# A reader MUST fail if it does not understand the `prefix`.
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if not hrp.startswith('ln'):
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raise ValueError("Does not start with ln")
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data = u5_to_bitarray(data)
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# Final signature 65 bytes, split it off.
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if len(data) < 65 * 8:
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raise ValueError("Too short to contain signature")
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sigdecoded = data[-65 * 8:].tobytes()
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data = bitstring.ConstBitStream(data[:-65 * 8])
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inv = Invoice()
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inv.pubkey = None
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m = re.search(r'[^\d]+', hrp[2:])
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if m:
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inv.currency = m.group(0)
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amountstr = hrp[2 + m.end():]
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# BOLT #11:
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#
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# A reader SHOULD indicate if amount is unspecified, otherwise it MUST
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# multiply `amount` by the `multiplier` value (if any) to derive the
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# amount required for payment.
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if amountstr != '':
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inv.amount = unshorten_amount(amountstr)
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inv.date = data.read(35).uint
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while data.pos != data.len:
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tag, tagdata, data = pull_tagged(data)
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# BOLT #11:
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#
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# A reader MUST skip over unknown fields, an `f` field with unknown
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# `version`, or a `p`, `h`, `n` or `r` field which does not have
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# `data_length` 52, 52, 53 or 82 respectively.
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data_length = len(tagdata) / 5
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if tag == 'r':
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inv.route_hints = RouteHintSet.from_bytes(trim_to_bytes(tagdata))
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continue
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if data_length != 82:
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inv.unknown_tags.append((tag, tagdata))
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continue
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tagbytes = trim_to_bytes(tagdata)
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inv.tags.append(('r', (
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tagbytes[0:33],
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tagbytes[33:41],
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tagdata[41 * 8:49 * 8].intbe,
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tagdata[49 * 8:51 * 8].intbe
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)))
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elif tag == 'f':
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fallback = parse_fallback(tagdata, inv.currency)
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if fallback:
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inv.tags.append(('f', fallback))
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else:
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# Incorrect version.
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inv.unknown_tags.append((tag, tagdata))
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continue
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elif tag == 'd':
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inv.tags.append(('d', trim_to_bytes(tagdata).decode('utf-8')))
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elif tag == 'h':
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if data_length != 52:
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inv.unknown_tags.append((tag, tagdata))
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continue
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inv.tags.append(('h', trim_to_bytes(tagdata)))
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elif tag == 'x':
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inv.tags.append(('x', tagdata.uint))
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elif tag == 'p':
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if data_length != 52:
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inv.unknown_tags.append((tag, tagdata))
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continue
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inv.paymenthash = trim_to_bytes(tagdata)
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elif tag == 'n':
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if data_length != 53:
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inv.unknown_tags.append((tag, tagdata))
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continue
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inv.pubkey = coincurve.PublicKey(trim_to_bytes(tagdata))
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elif tag == 'c':
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inv.min_final_cltv_expiry = tagdata.uint
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else:
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inv.unknown_tags.append((tag, tagdata))
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# BOLT #11:
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#
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# A reader MUST check that the `signature` is valid (see the `n` tagged
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# field specified below).
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if inv.pubkey: # Specified by `n`
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# BOLT #11:
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#
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# A reader MUST use the `n` field to validate the signature instead of
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# performing signature recovery if a valid `n` field is provided.
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inv.signature = inv.pubkey.ecdsa_deserialize_compact(sigdecoded[0:64])
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if not inv.pubkey.ecdsa_verify(bytearray([ord(c) for c in hrp]) + data.tobytes(), inv.signature):
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raise ValueError('Invalid signature')
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else: # Recover pubkey from signature.
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inv.signature = coincurve.ecdsa.deserialize_recoverable(
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sigdecoded[0:65])
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inv.pubkey = coincurve.PublicKey.from_signature_and_message(
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sigdecoded[0:65],
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bytearray([ord(c) for c in hrp]) + data.tobytes())
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return inv
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class RouteHint(object):
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length = 33 + 8 + 4 + 4 + 2
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def __init__(self):
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self.pubkey = None
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self.short_channel_id = None
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self.fee_base_msat = None
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self.fee_proportional_millionths = None
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self.cltv_expiry_delta = None
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@classmethod
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def from_bytes(cls, b):
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inst = RouteHint()
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inst.pubkey = b.read(33)
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inst.short_channel_id, = struct.unpack("!Q", b.read(8))
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inst.fee_base_msat, inst.fee_proportional_millionths, inst.cltv_expiry_delta = struct.unpack("!IIH", b.read(10))
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return inst
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def to_bytes(self):
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return self.pubkey + struct.pack(
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"!QIIH", self.short_channel_id, self.fee_base_msat,
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self.fee_proportional_millionths, self.cltv_expiry_delta
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)
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def __str__(self):
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pubkey = hexlify(self.pubkey).decode('ASCII')
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return f"RouteHint<pubkey={pubkey}, short_channel_id={self.short_channel_id}, fee_base_msat={self.fee_base_msat}, fee_prop={self.fee_proportional_millionths}, cltv_expiry_delta={self.cltv_expiry_delta}>"
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class RouteHintSet(object):
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def __init__(self):
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self.route_hints = []
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@classmethod
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def from_bytes(cls, b):
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if isinstance(b, bytes):
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b = BufferedReader(BytesIO(b))
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if not isinstance(b, BufferedReader):
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raise TypeError('from_bytes can only read from bytes-arrays or BufferedReader')
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if len(b.raw.getvalue()) % RouteHint.length != 0:
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raise TypeError("byte string is not a multiple of the route hint size: {}".format(
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len(b.raw.getvalue())
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))
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instance = RouteHintSet()
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while b.peek():
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instance.route_hints.append(RouteHint.from_bytes(b))
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return instance
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def to_bytes(self):
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return b''.join([rh.to_bytes() for rh in self.route_hints])
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def __str__(self):
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return "RouteHintSet[{}]".format(
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", ".join([str(rh) for rh in self.route_hints])
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)
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def add(self, rh: RouteHint):
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self.route_hints.append(rh)
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