# ported from lnd 42de4400bff5105352d0552155f73589166d162b from collections import namedtuple import binascii import json from enum import Enum, auto from typing import Optional from .util import bfh, PrintError, bh2u from .bitcoin import Hash, TYPE_SCRIPT, TYPE_ADDRESS from .bitcoin import redeem_script_to_address from .crypto import sha256 from . import ecc from .lnutil import Outpoint, LocalConfig, RemoteConfig, Keypair, OnlyPubkeyKeypair, ChannelConstraints, RevocationStore, EncumberedTransaction from .lnutil import get_per_commitment_secret_from_seed from .lnutil import make_commitment_output_to_remote_address, make_commitment_output_to_local_witness_script from .lnutil import secret_to_pubkey, derive_privkey, derive_pubkey, derive_blinded_pubkey, derive_blinded_privkey from .lnutil import sign_and_get_sig_string from .lnutil import make_htlc_tx_with_open_channel, make_commitment, make_received_htlc, make_offered_htlc from .lnutil import HTLC_TIMEOUT_WEIGHT, HTLC_SUCCESS_WEIGHT from .lnutil import funding_output_script, LOCAL, REMOTE, HTLCOwner, make_closing_tx, make_outputs from .lnutil import ScriptHtlc, SENT, RECEIVED from .transaction import Transaction, TxOutput, construct_witness from .simple_config import SimpleConfig, FEERATE_FALLBACK_STATIC_FEE RevokeAndAck = namedtuple("RevokeAndAck", ["per_commitment_secret", "next_per_commitment_point"]) class FeeUpdateProgress(Enum): FUNDEE_SIGNED = auto() FUNDEE_ACKED = auto() FUNDER_SIGNED = auto() FUNDEE_SIGNED = FeeUpdateProgress.FUNDEE_SIGNED FUNDEE_ACKED = FeeUpdateProgress.FUNDEE_ACKED FUNDER_SIGNED = FeeUpdateProgress.FUNDER_SIGNED from collections import namedtuple class FeeUpdate: def __init__(self, chan, rate): self.rate = rate self.progress = {FUNDEE_SIGNED: None, FUNDEE_ACKED: None, FUNDER_SIGNED: None} self.chan = chan def set(self, field): self.progress[field] = self.chan.current_height[LOCAL if self.chan.constraints.is_initiator else REMOTE] def had(self, field): """ returns true when the progress field given has been set at the current commitment number of the funder """ return self.progress[field] is not None def pending_feerate(self, subject): if self.had(FUNDEE_ACKED): return self.rate if subject == REMOTE and self.chan.constraints.is_initiator: return self.rate if subject == LOCAL and not self.chan.constraints.is_initiator: return self.rate # implicit return None class UpdateAddHtlc(namedtuple('UpdateAddHtlc', ['amount_msat', 'payment_hash', 'cltv_expiry', 'locked_in', 'htlc_id'])): __slots__ = () def __new__(cls, *args, **kwargs): if len(args) > 0: args = list(args) if type(args[1]) is str: args[1] = bfh(args[1]) args[3] = {HTLCOwner(int(x)): y for x,y in args[3].items()} return super().__new__(cls, *args) if type(kwargs['payment_hash']) is str: kwargs['payment_hash'] = bfh(kwargs['payment_hash']) if 'locked_in' not in kwargs: kwargs['locked_in'] = {LOCAL: None, REMOTE: None} else: kwargs['locked_in'] = {HTLCOwner(int(x)): y for x,y in kwargs['locked_in'].items()} return super().__new__(cls, **kwargs) def decodeAll(d, local): for k, v in d.items(): if k == 'revocation_store': yield (k, RevocationStore.from_json_obj(v)) elif k.endswith("_basepoint") or k.endswith("_key"): if local: yield (k, Keypair(**dict(decodeAll(v, local)))) else: yield (k, OnlyPubkeyKeypair(**dict(decodeAll(v, local)))) elif k in ["node_id", "channel_id", "short_channel_id", "pubkey", "privkey", "current_per_commitment_point", "next_per_commitment_point", "per_commitment_secret_seed", "current_commitment_signature", "current_htlc_signatures"] and v is not None: yield (k, binascii.unhexlify(v)) else: yield (k, v) def htlcsum(htlcs): return sum([x.amount_msat for x in htlcs]) class HTLCStateMachine(PrintError): def diagnostic_name(self): return str(self.name) def __init__(self, state, name = None): assert 'local_state' not in state self.config = {} self.config[LOCAL] = state["local_config"] if type(self.config[LOCAL]) is not LocalConfig: conf = dict(decodeAll(self.config[LOCAL], True)) self.config[LOCAL] = LocalConfig(**conf) assert type(self.config[LOCAL].htlc_basepoint.privkey) is bytes self.config[REMOTE] = state["remote_config"] if type(self.config[REMOTE]) is not RemoteConfig: conf = dict(decodeAll(self.config[REMOTE], False)) self.config[REMOTE] = RemoteConfig(**conf) assert type(self.config[REMOTE].htlc_basepoint.pubkey) is bytes self.channel_id = bfh(state["channel_id"]) if type(state["channel_id"]) not in (bytes, type(None)) else state["channel_id"] self.constraints = ChannelConstraints(**state["constraints"]) if type(state["constraints"]) is not ChannelConstraints else state["constraints"] self.funding_outpoint = Outpoint(**dict(decodeAll(state["funding_outpoint"], False))) if type(state["funding_outpoint"]) is not Outpoint else state["funding_outpoint"] self.node_id = bfh(state["node_id"]) if type(state["node_id"]) not in (bytes, type(None)) else state["node_id"] self.short_channel_id = bfh(state["short_channel_id"]) if type(state["short_channel_id"]) not in (bytes, type(None)) else state["short_channel_id"] self.short_channel_id_predicted = self.short_channel_id self.onion_keys = {int(k): bfh(v) for k,v in state['onion_keys'].items()} if 'onion_keys' in state else {} # FIXME this is a tx serialised in the custom electrum partial tx format. # we should not persist txns in this format. we should persist htlcs, and be able to derive # any past commitment transaction and use that instead; until then... self.remote_commitment_to_be_revoked = Transaction(state["remote_commitment_to_be_revoked"]) template = lambda: {'adds': {}, 'settles': []} self.log = {LOCAL: template(), REMOTE: template()} for strname, subject in [('remote_log', REMOTE), ('local_log', LOCAL)]: if strname not in state: continue for y in state[strname]: htlc = UpdateAddHtlc(**y) self.log[subject]['adds'][htlc.htlc_id] = htlc self.name = name self.fee_mgr = [] self.local_commitment = self.pending_local_commitment self.remote_commitment = self.pending_remote_commitment self._is_funding_txo_spent = None # "don't know" self.set_state('DISCONNECTED') self.lnwatcher = None self.settled = {LOCAL: state.get('settled_local', []), REMOTE: state.get('settled_remote', [])} def set_state(self, state: str): self._state = state def get_state(self): return self._state def set_funding_txo_spentness(self, is_spent: bool): assert isinstance(is_spent, bool) self._is_funding_txo_spent = is_spent def should_try_to_reestablish_peer(self) -> bool: return self._is_funding_txo_spent is False and self._state == 'DISCONNECTED' def get_funding_address(self): script = funding_output_script(self.config[LOCAL], self.config[REMOTE]) return redeem_script_to_address('p2wsh', script) def add_htlc(self, htlc): """ AddHTLC adds an HTLC to the state machine's local update log. This method should be called when preparing to send an outgoing HTLC. """ assert type(htlc) is dict htlc = UpdateAddHtlc(**htlc, htlc_id=self.config[LOCAL].next_htlc_id) self.log[LOCAL]['adds'][htlc.htlc_id] = htlc self.print_error("add_htlc") self.config[LOCAL]=self.config[LOCAL]._replace(next_htlc_id=htlc.htlc_id + 1) return htlc.htlc_id def receive_htlc(self, htlc): """ ReceiveHTLC adds an HTLC to the state machine's remote update log. This method should be called in response to receiving a new HTLC from the remote party. """ assert type(htlc) is dict htlc = UpdateAddHtlc(**htlc, htlc_id = self.config[REMOTE].next_htlc_id) self.log[REMOTE]['adds'][htlc.htlc_id] = htlc self.print_error("receive_htlc") self.config[REMOTE]=self.config[REMOTE]._replace(next_htlc_id=htlc.htlc_id + 1) return htlc.htlc_id def sign_next_commitment(self): """ SignNextCommitment signs a new commitment which includes any previous unsettled HTLCs, any new HTLCs, and any modifications to prior HTLCs committed in previous commitment updates. Signing a new commitment decrements the available revocation window by 1. After a successful method call, the remote party's commitment chain is extended by a new commitment which includes all updates to the HTLC log prior to this method invocation. The first return parameter is the signature for the commitment transaction itself, while the second parameter is a slice of all HTLC signatures (if any). The HTLC signatures are sorted according to the BIP 69 order of the HTLC's on the commitment transaction. """ for htlc in self.log[LOCAL]['adds'].values(): if htlc.locked_in[LOCAL] is None: htlc.locked_in[LOCAL] = self.config[LOCAL].ctn self.print_error("sign_next_commitment") pending_remote_commitment = self.pending_remote_commitment sig_64 = sign_and_get_sig_string(pending_remote_commitment, self.config[LOCAL], self.config[REMOTE]) their_remote_htlc_privkey_number = derive_privkey( int.from_bytes(self.config[LOCAL].htlc_basepoint.privkey, 'big'), self.config[REMOTE].next_per_commitment_point) their_remote_htlc_privkey = their_remote_htlc_privkey_number.to_bytes(32, 'big') for_us = False htlcsigs = [] for we_receive, htlcs in zip([True, False], [self.included_htlcs(REMOTE, REMOTE), self.included_htlcs(REMOTE, LOCAL)]): for htlc in htlcs: args = [self.config[REMOTE].next_per_commitment_point, for_us, we_receive, pending_remote_commitment, htlc] htlc_tx = make_htlc_tx_with_open_channel(self, *args) sig = bfh(htlc_tx.sign_txin(0, their_remote_htlc_privkey)) htlc_sig = ecc.sig_string_from_der_sig(sig[:-1]) htlcsigs.append((pending_remote_commitment.htlc_output_indices[htlc.payment_hash], htlc_sig)) for pending_fee in self.fee_mgr: if not self.constraints.is_initiator: pending_fee.set(FUNDEE_SIGNED) if self.constraints.is_initiator and pending_fee.had(FUNDEE_ACKED): pending_fee.set(FUNDER_SIGNED) self.process_new_offchain_ctx(pending_remote_commitment, ours=False) htlcsigs.sort() htlcsigs = [x[1] for x in htlcsigs] return sig_64, htlcsigs def receive_new_commitment(self, sig, htlc_sigs): """ ReceiveNewCommitment process a signature for a new commitment state sent by the remote party. This method should be called in response to the remote party initiating a new change, or when the remote party sends a signature fully accepting a new state we've initiated. If we are able to successfully validate the signature, then the generated commitment is added to our local commitment chain. Once we send a revocation for our prior state, then this newly added commitment becomes our current accepted channel state. """ self.print_error("receive_new_commitment") for htlc in self.log[REMOTE]['adds'].values(): if htlc.locked_in[REMOTE] is None: htlc.locked_in[REMOTE] = self.config[REMOTE].ctn assert len(htlc_sigs) == 0 or type(htlc_sigs[0]) is bytes pending_local_commitment = self.pending_local_commitment preimage_hex = pending_local_commitment.serialize_preimage(0) pre_hash = Hash(bfh(preimage_hex)) if not ecc.verify_signature(self.config[REMOTE].multisig_key.pubkey, sig, pre_hash): raise Exception('failed verifying signature of our updated commitment transaction: ' + bh2u(sig) + ' preimage is ' + preimage_hex) _, this_point, _ = self.points for htlcs, we_receive in [(self.included_htlcs(LOCAL, REMOTE), True), (self.included_htlcs(LOCAL, LOCAL), False)]: for htlc in htlcs: htlc_tx = make_htlc_tx_with_open_channel(self, this_point, True, we_receive, pending_local_commitment, htlc) pre_hash = Hash(bfh(htlc_tx.serialize_preimage(0))) remote_htlc_pubkey = derive_pubkey(self.config[REMOTE].htlc_basepoint.pubkey, this_point) for idx, sig in enumerate(htlc_sigs): if ecc.verify_signature(remote_htlc_pubkey, sig, pre_hash): del htlc_sigs[idx] break else: raise Exception(f'failed verifying HTLC signatures: {htlc}') if len(htlc_sigs) != 0: # all sigs should have been popped above raise Exception('failed verifying HTLC signatures: invalid amount of correct signatures') for pending_fee in self.fee_mgr: if not self.constraints.is_initiator: pending_fee.set(FUNDEE_SIGNED) if self.constraints.is_initiator and pending_fee.had(FUNDEE_ACKED): pending_fee.set(FUNDER_SIGNED) self.process_new_offchain_ctx(pending_local_commitment, ours=True) def revoke_current_commitment(self): """ RevokeCurrentCommitment revokes the next lowest unrevoked commitment transaction in the local commitment chain. As a result the edge of our revocation window is extended by one, and the tail of our local commitment chain is advanced by a single commitment. This now lowest unrevoked commitment becomes our currently accepted state within the channel. This method also returns the set of HTLC's currently active within the commitment transaction. This return value allows callers to act once an HTLC has been locked into our commitment transaction. """ self.print_error("revoke_current_commitment") last_secret, this_point, next_point = self.points new_local_feerate = self.config[LOCAL].feerate new_remote_feerate = self.config[REMOTE].feerate for pending_fee in self.fee_mgr[:]: if not self.constraints.is_initiator and pending_fee.had(FUNDEE_SIGNED): new_local_feerate = new_remote_feerate = pending_fee.rate self.fee_mgr.remove(pending_fee) print("FEERATE CHANGE COMPLETE (non-initiator)") if self.constraints.is_initiator and pending_fee.had(FUNDER_SIGNED): new_local_feerate = new_remote_feerate = pending_fee.rate self.fee_mgr.remove(pending_fee) print("FEERATE CHANGE COMPLETE (initiator)") self.config[LOCAL]=self.config[LOCAL]._replace( ctn=self.config[LOCAL].ctn + 1, feerate=new_local_feerate ) self.config[REMOTE]=self.config[REMOTE]._replace( feerate=new_remote_feerate ) self.local_commitment = self.pending_local_commitment return RevokeAndAck(last_secret, next_point), "current htlcs" @property def points(self): last_small_num = self.config[LOCAL].ctn this_small_num = last_small_num + 1 next_small_num = last_small_num + 2 last_secret = get_per_commitment_secret_from_seed(self.config[LOCAL].per_commitment_secret_seed, RevocationStore.START_INDEX - last_small_num) this_secret = get_per_commitment_secret_from_seed(self.config[LOCAL].per_commitment_secret_seed, RevocationStore.START_INDEX - this_small_num) this_point = secret_to_pubkey(int.from_bytes(this_secret, 'big')) next_secret = get_per_commitment_secret_from_seed(self.config[LOCAL].per_commitment_secret_seed, RevocationStore.START_INDEX - next_small_num) next_point = secret_to_pubkey(int.from_bytes(next_secret, 'big')) return last_secret, this_point, next_point # TODO batch sweeps # TODO sweep HTLC outputs def process_new_offchain_ctx(self, ctx, ours: bool): if not self.lnwatcher: return outpoint = self.funding_outpoint.to_str() if ours: ctn = self.config[LOCAL].ctn + 1 our_per_commitment_secret = get_per_commitment_secret_from_seed( self.config[LOCAL].per_commitment_secret_seed, RevocationStore.START_INDEX - ctn) our_cur_pcp = ecc.ECPrivkey(our_per_commitment_secret).get_public_key_bytes(compressed=True) encumbered_sweeptx = maybe_create_sweeptx_for_our_ctx_to_local(self, ctx, our_cur_pcp, self.sweep_address) else: their_cur_pcp = self.config[REMOTE].next_per_commitment_point encumbered_sweeptx = maybe_create_sweeptx_for_their_ctx_to_remote(self, ctx, their_cur_pcp, self.sweep_address) self.lnwatcher.add_sweep_tx(outpoint, ctx.txid(), encumbered_sweeptx) def process_new_revocation_secret(self, per_commitment_secret: bytes): if not self.lnwatcher: return outpoint = self.funding_outpoint.to_str() ctx = self.remote_commitment_to_be_revoked encumbered_sweeptx = maybe_create_sweeptx_for_their_ctx_to_local(self, ctx, per_commitment_secret, self.sweep_address) self.lnwatcher.add_sweep_tx(outpoint, ctx.txid(), encumbered_sweeptx) def receive_revocation(self, revocation): """ ReceiveRevocation processes a revocation sent by the remote party for the lowest unrevoked commitment within their commitment chain. We receive a revocation either during the initial session negotiation wherein revocation windows are extended, or in response to a state update that we initiate. If successful, then the remote commitment chain is advanced by a single commitment, and a log compaction is attempted. Returns the forwarding package corresponding to the remote commitment height that was revoked. """ self.print_error("receive_revocation") cur_point = self.config[REMOTE].current_per_commitment_point derived_point = ecc.ECPrivkey(revocation.per_commitment_secret).get_public_key_bytes(compressed=True) if cur_point != derived_point: raise Exception('revoked secret not for current point') # FIXME not sure this is correct... but it seems to work # if there are update_add_htlc msgs between commitment_signed and rev_ack, # this might break prev_remote_commitment = self.pending_remote_commitment self.config[REMOTE].revocation_store.add_next_entry(revocation.per_commitment_secret) self.process_new_revocation_secret(revocation.per_commitment_secret) def mark_settled(subject): """ find pending settlements for subject (LOCAL or REMOTE) and mark them settled, return value of settled htlcs """ old_amount = htlcsum(self.htlcs(subject, False)) for htlc_id in self.log[-subject]['settles']: adds = self.log[subject]['adds'] htlc = adds.pop(htlc_id) self.settled[subject].append(htlc.amount_msat) self.log[-subject]['settles'].clear() return old_amount - htlcsum(self.htlcs(subject, False)) sent_this_batch = mark_settled(LOCAL) received_this_batch = mark_settled(REMOTE) next_point = self.config[REMOTE].next_per_commitment_point print("RECEIVED", received_this_batch) print("SENT", sent_this_batch) self.config[REMOTE]=self.config[REMOTE]._replace( ctn=self.config[REMOTE].ctn + 1, current_per_commitment_point=next_point, next_per_commitment_point=revocation.next_per_commitment_point, amount_msat=self.config[REMOTE].amount_msat + (sent_this_batch - received_this_batch) ) self.config[LOCAL]=self.config[LOCAL]._replace( amount_msat = self.config[LOCAL].amount_msat + (received_this_batch - sent_this_batch) ) for pending_fee in self.fee_mgr: if self.constraints.is_initiator: pending_fee.set(FUNDEE_ACKED) self.local_commitment = self.pending_local_commitment self.remote_commitment = self.pending_remote_commitment self.remote_commitment_to_be_revoked = prev_remote_commitment return received_this_batch, sent_this_batch def balance(self, subject): initial = self.config[subject].initial_msat initial -= sum(self.settled[subject]) initial += sum(self.settled[-subject]) assert initial == self.config[subject].amount_msat return initial def amounts(self): remote_settled= htlcsum(self.htlcs(REMOTE, False)) local_settled= htlcsum(self.htlcs(LOCAL, False)) unsettled_local = htlcsum(self.htlcs(LOCAL, True)) unsettled_remote = htlcsum(self.htlcs(REMOTE, True)) remote_msat = self.config[REMOTE].amount_msat -\ unsettled_remote + local_settled - remote_settled local_msat = self.config[LOCAL].amount_msat -\ unsettled_local + remote_settled - local_settled return remote_msat, local_msat def included_htlcs(self, subject, htlc_initiator): """ return filter of non-dust htlcs for subjects commitment transaction, initiated by given party """ feerate = self.pending_feerate(subject) conf = self.config[subject] weight = HTLC_SUCCESS_WEIGHT if subject != htlc_initiator else HTLC_TIMEOUT_WEIGHT htlcs = self.htlcs(htlc_initiator, only_pending=True) fee_for_htlc = lambda htlc: htlc.amount_msat // 1000 - (weight * feerate // 1000) return filter(lambda htlc: fee_for_htlc(htlc) >= conf.dust_limit_sat, htlcs) @property def pending_remote_commitment(self): this_point = self.config[REMOTE].next_per_commitment_point return self.make_commitment(REMOTE, this_point) def pending_feerate(self, subject): candidate = None for pending_fee in self.fee_mgr: x = pending_fee.pending_feerate(subject) if x is not None: candidate = x feerate = candidate if candidate is not None else self._committed_feerate[subject] return feerate @property def _committed_feerate(self): return {LOCAL: self.config[LOCAL].feerate, REMOTE: self.config[REMOTE].feerate} @property def pending_local_commitment(self): _, this_point, _ = self.points return self.make_commitment(LOCAL, this_point) def total_msat(self, sub): return sum(self.settled[sub]) def htlcs(self, subject, only_pending): """ only_pending: require the htlc's settlement to be pending (needs additional signatures/acks) """ update_log = self.log[subject] other_log = self.log[-subject] res = [] for htlc in update_log['adds'].values(): locked_in = htlc.locked_in[subject] if locked_in is None or only_pending == (htlc.htlc_id in other_log['settles']): continue res.append(htlc) return res def settle_htlc(self, preimage, htlc_id): """ SettleHTLC attempts to settle an existing outstanding received HTLC. """ self.print_error("settle_htlc") htlc = self.log[REMOTE]['adds'][htlc_id] assert htlc.payment_hash == sha256(preimage) self.log[LOCAL]['settles'].append(htlc_id) def receive_htlc_settle(self, preimage, htlc_index): self.print_error("receive_htlc_settle") htlc = self.log[LOCAL]['adds'][htlc_index] assert htlc.payment_hash == sha256(preimage) self.log[REMOTE]['settles'].append(htlc_index) def receive_fail_htlc(self, htlc_id): self.print_error("receive_fail_htlc") self.log[LOCAL]['adds'].pop(htlc_id) @property def current_height(self): return {LOCAL: self.config[LOCAL].ctn, REMOTE: self.config[REMOTE].ctn} @property def pending_local_fee(self): return self.constraints.capacity - sum(x[2] for x in self.pending_local_commitment.outputs()) def update_fee(self, feerate): if not self.constraints.is_initiator: raise Exception("only initiator can update_fee, this counterparty is not initiator") pending_fee = FeeUpdate(self, rate=feerate) self.fee_mgr.append(pending_fee) def receive_update_fee(self, feerate): if self.constraints.is_initiator: raise Exception("only the non-initiator can receive_update_fee, this counterparty is initiator") pending_fee = FeeUpdate(self, rate=feerate) self.fee_mgr.append(pending_fee) def remove_uncommitted_htlcs_from_log(self, subject): """ returns - the htlcs with uncommited (not locked in) htlcs removed - a list of htlc_ids that were removed """ removed = [] htlcs = [] for i in self.log[subject]['adds'].values(): locked_in = i.locked_in[LOCAL] is not None or i.locked_in[REMOTE] is not None if locked_in: htlcs.append(i._asdict()) else: removed.append(i.htlc_id) return htlcs, removed def to_save(self): # need to forget about uncommited htlcs # since we must assume they don't know about it, # if it was not acked remote_filtered, remote_removed = self.remove_uncommitted_htlcs_from_log(REMOTE) local_filtered, local_removed = self.remove_uncommitted_htlcs_from_log(LOCAL) to_save = { "local_config": self.config[LOCAL], "remote_config": self.config[REMOTE], "channel_id": self.channel_id, "short_channel_id": self.short_channel_id, "constraints": self.constraints, "funding_outpoint": self.funding_outpoint, "node_id": self.node_id, "remote_commitment_to_be_revoked": str(self.remote_commitment_to_be_revoked), "remote_log": remote_filtered, "local_log": local_filtered, "onion_keys": {str(k): bh2u(v) for k, v in self.onion_keys.items()}, "settled_local": self.settled[LOCAL], "settled_remote": self.settled[REMOTE], } # htlcs number must be monotonically increasing, # so we have to decrease the counter if len(remote_removed) != 0: assert min(remote_removed) < to_save['remote_config'].next_htlc_id to_save['remote_config'] = to_save['remote_config']._replace(next_htlc_id = min(remote_removed)) if len(local_removed) != 0: assert min(local_removed) < to_save['local_config'].next_htlc_id to_save['local_config'] = to_save['local_config']._replace(next_htlc_id = min(local_removed)) return to_save def serialize(self): namedtuples_to_dict = lambda v: {i: j._asdict() if isinstance(j, tuple) else j for i, j in v._asdict().items()} serialized_channel = {k: namedtuples_to_dict(v) if isinstance(v, tuple) else v for k, v in self.to_save().items()} class MyJsonEncoder(json.JSONEncoder): def default(self, o): if isinstance(o, bytes): return binascii.hexlify(o).decode("ascii") if isinstance(o, RevocationStore): return o.serialize() return super(MyJsonEncoder, self) dumped = MyJsonEncoder().encode(serialized_channel) roundtripped = json.loads(dumped) reconstructed = HTLCStateMachine(roundtripped) if reconstructed.to_save() != self.to_save(): from pprint import pformat try: from deepdiff import DeepDiff except ImportError: raise Exception("Channels did not roundtrip serialization without changes:\n" + pformat(reconstructed.to_save()) + "\n" + pformat(self.to_save())) else: raise Exception("Channels did not roundtrip serialization without changes:\n" + pformat(DeepDiff(reconstructed.to_save(), self.to_save()))) return roundtripped def __str__(self): return self.serialize() def make_commitment(self, subject, this_point) -> Transaction: remote_msat, local_msat = self.amounts() assert local_msat >= 0 assert remote_msat >= 0 this_config = self.config[subject] other_config = self.config[-subject] other_htlc_pubkey = derive_pubkey(other_config.htlc_basepoint.pubkey, this_point) this_htlc_pubkey = derive_pubkey(this_config.htlc_basepoint.pubkey, this_point) other_revocation_pubkey = derive_blinded_pubkey(other_config.revocation_basepoint.pubkey, this_point) htlcs = [] for htlc in self.included_htlcs(subject, -subject): htlcs.append( ScriptHtlc( make_received_htlc( other_revocation_pubkey, other_htlc_pubkey, this_htlc_pubkey, htlc.payment_hash, htlc.cltv_expiry), htlc)) for htlc in self.included_htlcs(subject, subject): htlcs.append( ScriptHtlc( make_offered_htlc( other_revocation_pubkey, other_htlc_pubkey, this_htlc_pubkey, htlc.payment_hash), htlc)) if subject != LOCAL: remote_msat, local_msat = local_msat, remote_msat payment_pubkey = derive_pubkey(other_config.payment_basepoint.pubkey, this_point) return make_commitment( self.config[subject].ctn + 1, this_config.multisig_key.pubkey, other_config.multisig_key.pubkey, payment_pubkey, self.config[LOCAL].payment_basepoint.pubkey, self.config[REMOTE].payment_basepoint.pubkey, other_revocation_pubkey, derive_pubkey(this_config.delayed_basepoint.pubkey, this_point), other_config.to_self_delay, *self.funding_outpoint, self.constraints.capacity, local_msat, remote_msat, this_config.dust_limit_sat, self.pending_feerate(subject), subject == LOCAL, self.constraints.is_initiator, htlcs=htlcs) def make_closing_tx(self, local_script: bytes, remote_script: bytes, fee_sat: Optional[int] = None) -> (bytes, int): if fee_sat is None: fee_sat = self.pending_local_fee _, outputs = make_outputs(fee_sat * 1000, True, self.config[LOCAL].amount_msat, self.config[REMOTE].amount_msat, (TYPE_SCRIPT, bh2u(local_script)), (TYPE_SCRIPT, bh2u(remote_script)), [], self.config[LOCAL].dust_limit_sat) closing_tx = make_closing_tx(self.config[LOCAL].multisig_key.pubkey, self.config[REMOTE].multisig_key.pubkey, self.config[LOCAL].payment_basepoint.pubkey, self.config[REMOTE].payment_basepoint.pubkey, # TODO hardcoded we_are_initiator: True, *self.funding_outpoint, self.constraints.capacity, outputs) der_sig = bfh(closing_tx.sign_txin(0, self.config[LOCAL].multisig_key.privkey)) sig = ecc.sig_string_from_der_sig(der_sig[:-1]) return sig, fee_sat def maybe_create_sweeptx_for_their_ctx_to_remote(chan, ctx, their_pcp: bytes, sweep_address) -> Optional[EncumberedTransaction]: assert isinstance(their_pcp, bytes) payment_bp_privkey = ecc.ECPrivkey(chan.config[LOCAL].payment_basepoint.privkey) our_payment_privkey = derive_privkey(payment_bp_privkey.secret_scalar, their_pcp) our_payment_privkey = ecc.ECPrivkey.from_secret_scalar(our_payment_privkey) our_payment_pubkey = our_payment_privkey.get_public_key_bytes(compressed=True) to_remote_address = make_commitment_output_to_remote_address(our_payment_pubkey) for output_idx, (type_, addr, val) in enumerate(ctx.outputs()): if type_ == TYPE_ADDRESS and addr == to_remote_address: break else: return None sweep_tx = create_sweeptx_their_ctx_to_remote(address=sweep_address, ctx=ctx, output_idx=output_idx, our_payment_privkey=our_payment_privkey) return EncumberedTransaction(sweep_tx, csv_delay=0) def maybe_create_sweeptx_for_their_ctx_to_local(chan, ctx, per_commitment_secret: bytes, sweep_address) -> Optional[EncumberedTransaction]: assert isinstance(per_commitment_secret, bytes) per_commitment_point = ecc.ECPrivkey(per_commitment_secret).get_public_key_bytes(compressed=True) revocation_privkey = derive_blinded_privkey(chan.config[LOCAL].revocation_basepoint.privkey, per_commitment_secret) revocation_pubkey = ecc.ECPrivkey(revocation_privkey).get_public_key_bytes(compressed=True) to_self_delay = chan.config[LOCAL].to_self_delay delayed_pubkey = derive_pubkey(chan.config[REMOTE].delayed_basepoint.pubkey, per_commitment_point) witness_script = bh2u(make_commitment_output_to_local_witness_script( revocation_pubkey, to_self_delay, delayed_pubkey)) to_local_address = redeem_script_to_address('p2wsh', witness_script) for output_idx, o in enumerate(ctx.outputs()): if o.type == TYPE_ADDRESS and o.address == to_local_address: break else: return None sweep_tx = create_sweeptx_ctx_to_local(address=sweep_address, ctx=ctx, output_idx=output_idx, witness_script=witness_script, privkey=revocation_privkey, is_revocation=True) return EncumberedTransaction(sweep_tx, csv_delay=0) def maybe_create_sweeptx_for_our_ctx_to_local(chan, ctx, our_pcp: bytes, sweep_address) -> Optional[EncumberedTransaction]: assert isinstance(our_pcp, bytes) delayed_bp_privkey = ecc.ECPrivkey(chan.config[LOCAL].delayed_basepoint.privkey) our_localdelayed_privkey = derive_privkey(delayed_bp_privkey.secret_scalar, our_pcp) our_localdelayed_privkey = ecc.ECPrivkey.from_secret_scalar(our_localdelayed_privkey) our_localdelayed_pubkey = our_localdelayed_privkey.get_public_key_bytes(compressed=True) revocation_pubkey = derive_blinded_pubkey(chan.config[REMOTE].revocation_basepoint.pubkey, our_pcp) to_self_delay = chan.config[REMOTE].to_self_delay witness_script = bh2u(make_commitment_output_to_local_witness_script( revocation_pubkey, to_self_delay, our_localdelayed_pubkey)) to_local_address = redeem_script_to_address('p2wsh', witness_script) for output_idx, o in enumerate(ctx.outputs()): if o.type == TYPE_ADDRESS and o.address == to_local_address: break else: return None sweep_tx = create_sweeptx_ctx_to_local(address=sweep_address, ctx=ctx, output_idx=output_idx, witness_script=witness_script, privkey=our_localdelayed_privkey.get_secret_bytes(), is_revocation=False, to_self_delay=to_self_delay) return EncumberedTransaction(sweep_tx, csv_delay=to_self_delay) def create_sweeptx_their_ctx_to_remote(address, ctx, output_idx: int, our_payment_privkey: ecc.ECPrivkey, fee_per_kb: int=None) -> Transaction: our_payment_pubkey = our_payment_privkey.get_public_key_hex(compressed=True) val = ctx.outputs()[output_idx].value sweep_inputs = [{ 'type': 'p2wpkh', 'x_pubkeys': [our_payment_pubkey], 'num_sig': 1, 'prevout_n': output_idx, 'prevout_hash': ctx.txid(), 'value': val, 'coinbase': False, 'signatures': [None], }] tx_size_bytes = 110 # approx size of p2wpkh->p2wpkh if fee_per_kb is None: fee_per_kb = FEERATE_FALLBACK_STATIC_FEE fee = SimpleConfig.estimate_fee_for_feerate(fee_per_kb, tx_size_bytes) sweep_outputs = [TxOutput(TYPE_ADDRESS, address, val-fee)] sweep_tx = Transaction.from_io(sweep_inputs, sweep_outputs) sweep_tx.set_rbf(True) sweep_tx.sign({our_payment_pubkey: (our_payment_privkey.get_secret_bytes(), True)}) if not sweep_tx.is_complete(): raise Exception('channel close sweep tx is not complete') return sweep_tx def create_sweeptx_ctx_to_local(address, ctx, output_idx: int, witness_script: str, privkey: bytes, is_revocation: bool, to_self_delay: int=None, fee_per_kb: int=None) -> Transaction: """Create a txn that sweeps the 'to_local' output of a commitment transaction into our wallet. privkey: either revocation_privkey or localdelayed_privkey is_revocation: tells us which ^ """ val = ctx.outputs()[output_idx].value sweep_inputs = [{ 'scriptSig': '', 'type': 'p2wsh', 'signatures': [], 'num_sig': 0, 'prevout_n': output_idx, 'prevout_hash': ctx.txid(), 'value': val, 'coinbase': False, 'preimage_script': witness_script, }] if to_self_delay is not None: sweep_inputs[0]['sequence'] = to_self_delay tx_size_bytes = 121 # approx size of to_local -> p2wpkh if fee_per_kb is None: fee_per_kb = FEERATE_FALLBACK_STATIC_FEE fee = SimpleConfig.estimate_fee_for_feerate(fee_per_kb, tx_size_bytes) sweep_outputs = [TxOutput(TYPE_ADDRESS, address, val - fee)] sweep_tx = Transaction.from_io(sweep_inputs, sweep_outputs, version=2) sig = sweep_tx.sign_txin(0, privkey) witness = construct_witness([sig, int(is_revocation), witness_script]) sweep_tx.inputs()[0]['witness'] = witness return sweep_tx