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369 lines
17 KiB
369 lines
17 KiB
# ported from lnd 42de4400bff5105352d0552155f73589166d162b
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from ecdsa.util import sigencode_string_canonize, sigdecode_der
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from .util import bfh, PrintError
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from collections import namedtuple
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from ecdsa.curves import SECP256k1
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from .crypto import sha256
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SettleHtlc = namedtuple("SettleHtlc", ["htlc_id"])
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RevokeAndAck = namedtuple("RevokeAndAck", ["height", "per_commitment_secret", "next_per_commitment_point"])
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class UpdateAddHtlc:
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def __init__(self, amount_msat, payment_hash, cltv_expiry, total_fee):
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self.amount_msat = amount_msat
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self.payment_hash = payment_hash
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self.cltv_expiry = cltv_expiry
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self.total_fee = total_fee
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# the height the htlc was locked in at, or None
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self.r_locked_in = None
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self.l_locked_in = None
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self.htlc_id = None
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def as_tuple(self):
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return (self.htlc_id, self.amount_msat, self.payment_hash, self.cltv_expiry, self.r_locked_in, self.l_locked_in, self.total_fee)
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def __hash__(self):
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return hash(self.as_tuple())
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def __eq__(self, o):
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return type(o) is UpdateAddHtlc and self.as_tuple() == o.as_tuple()
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def __repr__(self):
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return "UpdateAddHtlc" + str(self.as_tuple())
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class HTLCStateMachine(PrintError):
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def lookup_htlc(self, log, htlc_id):
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assert type(htlc_id) is int
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for htlc in log:
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if type(htlc) is not UpdateAddHtlc: continue
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if htlc.htlc_id == htlc_id:
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return htlc
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assert False, self.diagnostic_name() + ": htlc_id {} not found in {}".format(htlc_id, log)
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def diagnostic_name(self):
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return str(self.name)
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def __init__(self, state, name = None):
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self.state = state
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self.local_update_log = []
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self.remote_update_log = []
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self.name = name
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self.l_current_height = 0
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self.r_current_height = 0
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self.total_msat_sent = 0
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self.total_msat_received = 0
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def add_htlc(self, htlc):
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"""
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AddHTLC adds an HTLC to the state machine's local update log. This method
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should be called when preparing to send an outgoing HTLC.
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"""
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assert type(htlc) is UpdateAddHtlc
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self.local_update_log.append(htlc)
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self.print_error("add_htlc")
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htlc_id = len(self.local_update_log)-1
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htlc.htlc_id = htlc_id
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return htlc_id
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def receive_htlc(self, htlc):
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"""
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ReceiveHTLC adds an HTLC to the state machine's remote update log. This
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method should be called in response to receiving a new HTLC from the remote
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party.
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"""
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assert type(htlc) is UpdateAddHtlc
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self.remote_update_log.append(htlc)
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self.print_error("receive_htlc")
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htlc_id = len(self.remote_update_log)-1
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htlc.htlc_id = htlc_id
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return htlc_id
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def sign_next_commitment(self):
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"""
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SignNextCommitment signs a new commitment which includes any previous
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unsettled HTLCs, any new HTLCs, and any modifications to prior HTLCs
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committed in previous commitment updates. Signing a new commitment
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decrements the available revocation window by 1. After a successful method
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call, the remote party's commitment chain is extended by a new commitment
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which includes all updates to the HTLC log prior to this method invocation.
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The first return parameter is the signature for the commitment transaction
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itself, while the second parameter is a slice of all HTLC signatures (if
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any). The HTLC signatures are sorted according to the BIP 69 order of the
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HTLC's on the commitment transaction.
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"""
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from .lnbase import sign_and_get_sig_string, derive_privkey, make_htlc_tx_with_open_channel
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self.l_current_height += 1
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for htlc in self.local_update_log:
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if not type(htlc) is UpdateAddHtlc: continue
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if htlc.l_locked_in is None: htlc.l_locked_in = self.l_current_height
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for htlc in self.remote_update_log:
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if not type(htlc) is UpdateAddHtlc: continue
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if htlc.r_locked_in is None: htlc.r_locked_in = self.r_current_height
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self.print_error("sign_next_commitment")
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sig_64 = sign_and_get_sig_string(self.remote_commitment, self.state.local_config, self.state.remote_config)
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their_remote_htlc_privkey_number = derive_privkey(
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int.from_bytes(self.state.local_config.htlc_basepoint.privkey, 'big'),
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self.state.remote_state.next_per_commitment_point)
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their_remote_htlc_privkey = their_remote_htlc_privkey_number.to_bytes(32, 'big')
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for_us = False
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htlcsigs = []
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for we_receive, htlcs in zip([True, False], [self.htlcs_in_remote, self.htlcs_in_local]):
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assert len(htlcs) <= 1
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for htlc in htlcs:
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original_htlc_output_index = 0
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args = [self.state.remote_state.next_per_commitment_point, for_us, we_receive, htlc.amount_msat + htlc.total_fee, htlc.cltv_expiry, htlc.payment_hash, self.remote_commitment, original_htlc_output_index]
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print("args", args)
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htlc_tx = make_htlc_tx_with_open_channel(self.state, *args)
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sig = bfh(htlc_tx.sign_txin(0, their_remote_htlc_privkey))
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r, s = sigdecode_der(sig[:-1], SECP256k1.generator.order())
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htlc_sig = sigencode_string_canonize(r, s, SECP256k1.generator.order())
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htlcsigs.append((htlc_tx, htlc_sig))
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return sig_64, htlcsigs
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def receive_new_commitment(self, sig, htlc_sigs):
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"""
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ReceiveNewCommitment process a signature for a new commitment state sent by
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the remote party. This method should be called in response to the
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remote party initiating a new change, or when the remote party sends a
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signature fully accepting a new state we've initiated. If we are able to
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successfully validate the signature, then the generated commitment is added
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to our local commitment chain. Once we send a revocation for our prior
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state, then this newly added commitment becomes our current accepted channel
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state.
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"""
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self.print_error("receive_new_commitment")
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# TODO
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def revoke_current_commitment(self):
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"""
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RevokeCurrentCommitment revokes the next lowest unrevoked commitment
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transaction in the local commitment chain. As a result the edge of our
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revocation window is extended by one, and the tail of our local commitment
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chain is advanced by a single commitment. This now lowest unrevoked
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commitment becomes our currently accepted state within the channel. This
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method also returns the set of HTLC's currently active within the commitment
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transaction. This return value allows callers to act once an HTLC has been
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locked into our commitment transaction.
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"""
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from .lnbase import get_per_commitment_secret_from_seed, secret_to_pubkey
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self.r_current_height += 1
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self.print_error("revoke_current_commitment")
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chan = self.state
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last_small_num = chan.local_state.ctn
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next_small_num = last_small_num + 2
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this_small_num = last_small_num + 1
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last_secret = get_per_commitment_secret_from_seed(chan.local_state.per_commitment_secret_seed, 2**48-last_small_num-1)
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this_secret = get_per_commitment_secret_from_seed(chan.local_state.per_commitment_secret_seed, 2**48-this_small_num-1)
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this_point = secret_to_pubkey(int.from_bytes(this_secret, 'big'))
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next_secret = get_per_commitment_secret_from_seed(chan.local_state.per_commitment_secret_seed, 2**48-next_small_num-1)
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next_point = secret_to_pubkey(int.from_bytes(next_secret, 'big'))
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self.state = chan._replace(
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local_state=chan.local_state._replace(
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ctn=chan.local_state.ctn + 1
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)
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)
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return RevokeAndAck(self.r_current_height, last_secret, next_point), "current htlcs"
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def receive_revocation(self, revocation):
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"""
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ReceiveRevocation processes a revocation sent by the remote party for the
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lowest unrevoked commitment within their commitment chain. We receive a
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revocation either during the initial session negotiation wherein revocation
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windows are extended, or in response to a state update that we initiate. If
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successful, then the remote commitment chain is advanced by a single
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commitment, and a log compaction is attempted.
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Returns the forwarding package corresponding to the remote commitment height
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that was revoked.
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"""
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self.print_error("receive_revocation")
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settle_fails2 = []
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for x in self.remote_update_log:
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if type(x) is not SettleHtlc:
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continue
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settle_fails2.append(x)
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if revocation.height is not None:
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adds2 = list(x for x in self.htlcs_in_remote if x.r_locked_in == revocation.height)
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class FwdPkg:
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adds = adds2
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settle_fails = settle_fails2
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for x in settle_fails2:
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self.total_msat_sent += self.lookup_htlc(self.local_update_log, x.htlc_id).amount_msat
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# increase received_msat counter for htlc's that have been settled
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adds2 = self.gen_htlc_indices("remote")
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for htlc in adds2:
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htlc_id = htlc.htlc_id
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if SettleHtlc(htlc_id) in self.local_update_log:
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self.total_msat_received += self.lookup_htlc(self.remote_update_log, htlc_id).amount_msat
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# log compaction (remove entries relating to htlc's that have been settled)
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to_remove = []
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for x in filter(lambda x: type(x) is SettleHtlc, self.remote_update_log):
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to_remove += [y for y in self.local_update_log if y.htlc_id == x.htlc_id]
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# assert that we should have compacted the log earlier
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assert len(to_remove) <= 1, to_remove
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if len(to_remove) == 1:
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self.remote_update_log = [x for x in self.remote_update_log if x.htlc_id != to_remove[0].htlc_id]
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self.local_update_log = [x for x in self.local_update_log if x.htlc_id != to_remove[0].htlc_id]
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to_remove = []
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for x in filter(lambda x: type(x) is SettleHtlc, self.local_update_log):
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to_remove += [y for y in self.remote_update_log if y.htlc_id == x.htlc_id]
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assert len(to_remove) <= 1, to_remove
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if len(to_remove) == 1:
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self.local_update_log = [x for x in self.local_update_log if x.htlc_id != to_remove[0].htlc_id]
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self.remote_update_log = [x for x in self.remote_update_log if x.htlc_id != to_remove[0].htlc_id]
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self.state.remote_state.revocation_store.add_next_entry(revocation.per_commitment_secret)
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next_point = self.state.remote_state.next_per_commitment_point
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self.state = self.state._replace(
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remote_state=self.state.remote_state._replace(
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ctn=self.state.remote_state.ctn + 1,
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last_per_commitment_point=next_point,
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next_per_commitment_point=revocation.next_per_commitment_point,
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)
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)
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if revocation.height is not None:
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return FwdPkg
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else:
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return None
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@staticmethod
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def htlcsum(htlcs):
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return sum(x.amount_msat for x in htlcs), sum(x.total_fee for x in htlcs)
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@property
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def remote_commitment(self):
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from .lnbase import make_commitment_using_open_channel, make_received_htlc, make_offered_htlc, derive_pubkey, derive_blinded_pubkey
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htlc_value_local, total_fee_local = self.htlcsum(self.htlcs_in_local)
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htlc_value_remote, total_fee_remote = self.htlcsum(self.htlcs_in_remote)
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local_msat = self.state.local_state.amount_msat -\
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htlc_value_local
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remote_msat = self.state.remote_state.amount_msat -\
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htlc_value_remote
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assert local_msat > 0
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assert remote_msat > 0
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this_point = self.state.remote_state.next_per_commitment_point
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remote_htlc_pubkey = derive_pubkey(self.state.remote_config.htlc_basepoint.pubkey, this_point)
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local_htlc_pubkey = derive_pubkey(self.state.local_config.htlc_basepoint.pubkey, this_point)
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local_revocation_pubkey = derive_blinded_pubkey(self.state.local_config.revocation_basepoint.pubkey, this_point)
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remote_revocation_pubkey = derive_blinded_pubkey(self.state.remote_config.revocation_basepoint.pubkey, this_point)
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htlcs_in_local = []
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for htlc in self.htlcs_in_local:
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htlcs_in_local.append(
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( make_received_htlc(local_revocation_pubkey, local_htlc_pubkey, remote_htlc_pubkey, htlc.payment_hash, htlc.cltv_expiry), htlc.amount_msat + total_fee_local))
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htlcs_in_remote = []
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for htlc in self.htlcs_in_remote:
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htlcs_in_remote.append(
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( make_offered_htlc(remote_revocation_pubkey, remote_htlc_pubkey, local_htlc_pubkey, htlc.payment_hash), htlc.amount_msat + total_fee_remote))
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commit = make_commitment_using_open_channel(self.state, self.state.remote_state.ctn + 1,
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False, this_point,
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remote_msat - total_fee_remote, local_msat - total_fee_local, htlcs_in_local + htlcs_in_remote)
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assert len(commit.outputs()) == 2 + len(htlcs_in_local) + len(htlcs_in_remote)
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return commit
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@property
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def local_commitment(self):
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from .lnbase import make_commitment_using_open_channel, make_received_htlc, make_offered_htlc, derive_pubkey, derive_blinded_pubkey, get_per_commitment_secret_from_seed, secret_to_pubkey
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htlc_value_local, total_fee_local = self.htlcsum(self.htlcs_in_local)
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htlc_value_remote, total_fee_remote = self.htlcsum(self.htlcs_in_remote)
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print("htlc_value_local, total_fee_local", htlc_value_local, total_fee_local)
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local_msat = self.state.local_state.amount_msat -\
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htlc_value_local
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print("htlc_value_remote, total_fee_remote", htlc_value_remote, total_fee_remote)
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remote_msat = self.state.remote_state.amount_msat -\
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htlc_value_remote
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assert local_msat > 0
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assert remote_msat > 0
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this_small_num = self.state.local_state.ctn + 1
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this_secret = get_per_commitment_secret_from_seed(self.state.local_state.per_commitment_secret_seed, 2**48-this_small_num-1)
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this_point = secret_to_pubkey(int.from_bytes(this_secret, 'big'))
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remote_htlc_pubkey = derive_pubkey(self.state.remote_config.htlc_basepoint.pubkey, this_point)
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local_htlc_pubkey = derive_pubkey(self.state.local_config.htlc_basepoint.pubkey, this_point)
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local_revocation_pubkey = derive_blinded_pubkey(self.state.local_config.revocation_basepoint.pubkey, this_point)
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remote_revocation_pubkey = derive_blinded_pubkey(self.state.remote_config.revocation_basepoint.pubkey, this_point)
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htlcs_in_local = []
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for htlc in self.htlcs_in_local:
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print("adding local htlc", htlc)
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htlcs_in_local.append(
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( make_offered_htlc(local_revocation_pubkey, local_htlc_pubkey, remote_htlc_pubkey, htlc.payment_hash), htlc.amount_msat + total_fee_local))
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htlcs_in_remote = []
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for htlc in self.htlcs_in_remote:
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print("adding remote htlc", htlc)
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htlcs_in_remote.append(
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( make_received_htlc(remote_revocation_pubkey, remote_htlc_pubkey, local_htlc_pubkey, htlc.payment_hash, htlc.cltv_expiry), htlc.amount_msat + total_fee_remote))
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commit = make_commitment_using_open_channel(self.state, self.state.local_state.ctn + 1,
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True, this_point,
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local_msat - total_fee_local, remote_msat - total_fee_remote, htlcs_in_local + htlcs_in_remote)
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assert len(commit.outputs()) == 2 + len(htlcs_in_local) + len(htlcs_in_remote)
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return commit
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def gen_htlc_indices(self, subject):
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assert subject in ["local", "remote"]
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update_log = (self.remote_update_log if subject == "remote" else self.local_update_log)
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res = []
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for htlc in update_log:
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if type(htlc) is not UpdateAddHtlc:
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continue
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height = (self.r_current_height if subject == "remote" else self.l_current_height)
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locked_in = (htlc.r_locked_in if subject == "remote" else htlc.l_locked_in)
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if locked_in is None or locked_in < height:
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continue
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res.append(htlc)
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return res
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@property
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def htlcs_in_local(self):
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return self.gen_htlc_indices("local")
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@property
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def htlcs_in_remote(self):
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return self.gen_htlc_indices("remote")
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def settle_htlc(self, preimage, htlc_id, source_ref, dest_ref, close_key):
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"""
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SettleHTLC attempts to settle an existing outstanding received HTLC.
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"""
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htlc = self.lookup_htlc(self.remote_update_log, htlc_id)
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assert htlc.payment_hash == sha256(preimage)
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self.local_update_log.append(SettleHtlc(htlc_id))
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def receive_htlc_settle(self, preimage, htlc_index):
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htlc = self.lookup_htlc(self.local_update_log, htlc_index)
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assert htlc.payment_hash == sha256(preimage)
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assert len([x.htlc_id == htlc_index for x in self.local_update_log]) == 1
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self.remote_update_log.append(SettleHtlc(htlc_index))
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