lnutil+lnwire: implement ChannelType

electrum/lnutil.py

@@ -8,7 +8,6 @@ import json
 from collections import namedtuple, defaultdict
 from typing import NamedTuple, List, Tuple, Mapping, Optional, TYPE_CHECKING, Union, Dict, Set, Sequence
 import re
-import time
 import attr
 from aiorpcx import NetAddress
 
@@ -1029,6 +1028,12 @@ class LnFeatures(IntFlag):
     _ln_feature_contexts[OPTION_SHUTDOWN_ANYSEGWIT_REQ] = (LNFC.INIT | LNFC.NODE_ANN)
     _ln_feature_contexts[OPTION_SHUTDOWN_ANYSEGWIT_OPT] = (LNFC.INIT | LNFC.NODE_ANN)
 
+    OPTION_CHANNEL_TYPE_REQ = 1 << 44
+    OPTION_CHANNEL_TYPE_OPT = 1 << 45
+
+    _ln_feature_contexts[OPTION_CHANNEL_TYPE_REQ] = (LNFC.INIT | LNFC.NODE_ANN)
+    _ln_feature_contexts[OPTION_CHANNEL_TYPE_OPT] = (LNFC.INIT | LNFC.NODE_ANN)
+
     # temporary
     OPTION_TRAMPOLINE_ROUTING_REQ_ECLAIR = 1 << 50
     OPTION_TRAMPOLINE_ROUTING_OPT_ECLAIR = 1 << 51
@@ -1103,6 +1108,52 @@ class LnFeatures(IntFlag):
                 or get_ln_flag_pair_of_bit(flag) in our_flags)
 
 
+class ChannelType(IntFlag):
+    OPTION_LEGACY_CHANNEL = 0
+    OPTION_STATIC_REMOTEKEY = 1 << 12
+    OPTION_ANCHOR_OUTPUTS = 1 << 20
+    OPTION_ANCHORS_ZERO_FEE_HTLC_TX = 1 << 22
+
+    def discard_unknown_and_check(self):
+        """Discards unknown flags and checks flag combination."""
+        flags = list_enabled_bits(self)
+        known_channel_types = []
+        for flag in flags:
+            channel_type = ChannelType(1 << flag)
+            if channel_type.name:
+                known_channel_types.append(channel_type)
+        final_channel_type = known_channel_types[0]
+        for channel_type in known_channel_types[1:]:
+            final_channel_type |= channel_type
+
+        final_channel_type.check_combinations()
+        return final_channel_type
+
+    def check_combinations(self):
+        if self == ChannelType.OPTION_STATIC_REMOTEKEY:
+            pass
+        elif self == ChannelType.OPTION_ANCHOR_OUTPUTS | ChannelType.OPTION_STATIC_REMOTEKEY:
+            pass
+        elif self == ChannelType.OPTION_ANCHORS_ZERO_FEE_HTLC_TX | ChannelType.OPTION_STATIC_REMOTEKEY:
+            pass
+        else:
+            raise ValueError("Channel type is not a valid flag combination.")
+
+    def complies_with_features(self, features: LnFeatures) -> bool:
+        flags = list_enabled_bits(self)
+        complies = True
+        for flag in flags:
+            feature = LnFeatures(1 << flag)
+            complies &= features.supports(feature)
+        return complies
+
+    def to_bytes_minimal(self):
+        # MUST use the smallest bitmap possible to represent the channel type.
+        bit_length =self.value.bit_length()
+        byte_length = bit_length // 8 + int(bool(bit_length % 8))
+        return self.to_bytes(byte_length, byteorder='big')
+
+
 del LNFC  # name is ambiguous without context
 
 # features that are actually implemented and understood in our codebase:

electrum/lnwire/peer_wire.csv

@@ -53,6 +53,8 @@ msgdata,open_channel,channel_flags,byte,
 msgdata,open_channel,tlvs,open_channel_tlvs,
 tlvtype,open_channel_tlvs,upfront_shutdown_script,0
 tlvdata,open_channel_tlvs,upfront_shutdown_script,shutdown_scriptpubkey,byte,...
+tlvtype,open_channel_tlvs,channel_type,1
+tlvdata,open_channel_tlvs,channel_type,type,byte,...
 msgtype,accept_channel,33
 msgdata,accept_channel,temporary_channel_id,byte,32
 msgdata,accept_channel,dust_limit_satoshis,u64,
@@ -71,6 +73,8 @@ msgdata,accept_channel,first_per_commitment_point,point,
 msgdata,accept_channel,tlvs,accept_channel_tlvs,
 tlvtype,accept_channel_tlvs,upfront_shutdown_script,0
 tlvdata,accept_channel_tlvs,upfront_shutdown_script,shutdown_scriptpubkey,byte,...
+tlvtype,accept_channel_tlvs,channel_type,1
+tlvdata,accept_channel_tlvs,channel_type,type,byte,...
 msgtype,funding_created,34
 msgdata,funding_created,temporary_channel_id,byte,32
 msgdata,funding_created,funding_txid,sha256,

electrum/tests/test_lnutil.py

@@ -9,7 +9,7 @@ from electrum.lnutil import (RevocationStore, get_per_commitment_secret_from_see
                              derive_pubkey, make_htlc_tx, extract_ctn_from_tx, UnableToDeriveSecret,
                              get_compressed_pubkey_from_bech32, split_host_port, ConnStringFormatError,
                              ScriptHtlc, extract_nodeid, calc_fees_for_commitment_tx, UpdateAddHtlc, LnFeatures,
-                             ln_compare_features, IncompatibleLightningFeatures)
+                             ln_compare_features, IncompatibleLightningFeatures, ChannelType)
 from electrum.util import bh2u, bfh, MyEncoder
 from electrum.transaction import Transaction, PartialTransaction
 from electrum.lnworker import LNWallet
@@ -890,3 +890,15 @@ class TestLNUtil(ElectrumTestCase):
         self.assertEqual(
             None,
             LNWallet._decode_channel_update_msg(bytes.fromhex("0101") + msg_without_prefix))
+
+    def test_channel_type(self):
+        # test compliance and non compliance with LN features
+        features = LnFeatures(LnFeatures.BASIC_MPP_OPT | LnFeatures.OPTION_STATIC_REMOTEKEY_OPT)
+        self.assertTrue(ChannelType.OPTION_STATIC_REMOTEKEY.complies_with_features(features))
+
+        features = LnFeatures(LnFeatures.BASIC_MPP_OPT | LnFeatures.OPTION_TRAMPOLINE_ROUTING_OPT)
+        self.assertFalse(ChannelType.OPTION_STATIC_REMOTEKEY.complies_with_features(features))
+
+        # ignore unknown channel types
+        channel_type = ChannelType(0b10000000001000000000010).discard_unknown_and_check()
+        self.assertEqual(ChannelType(0b10000000001000000000000), channel_type)