clean up local/global features

electrum/lnbase.py

@@ -17,6 +17,7 @@ from typing import List
 import cryptography.hazmat.primitives.ciphers.aead as AEAD
 import aiorpcx
 
+from .util import list_enabled_bits
 from . import bitcoin
 from . import ecc
 from .ecc import sig_string_from_r_and_s, get_r_and_s_from_sig_string
@@ -30,8 +31,9 @@ from .lnhtlc import HTLCStateMachine, RevokeAndAck
 from .lnutil import (Outpoint, ChannelConfig, LocalState,
                      RemoteState, OnlyPubkeyKeypair, ChannelConstraints, RevocationStore,
                      funding_output_script, get_ecdh, get_per_commitment_secret_from_seed,
-                     secret_to_pubkey, LNPeerAddr, PaymentFailure,
-                     LOCAL, REMOTE, HTLCOwner, generate_keypair, LnKeyFamily)
+                     secret_to_pubkey, LNPeerAddr, PaymentFailure, LnLocalFeatures,
+                     LOCAL, REMOTE, HTLCOwner, generate_keypair, LnKeyFamily,
+                     get_ln_flag_pair_of_bit)
 from .lnrouter import NotFoundChanAnnouncementForUpdate, RouteEdge
 
 
@@ -290,7 +292,10 @@ class Peer(PrintError):
         self.announcement_signatures = defaultdict(asyncio.Queue)
         self.closing_signed = defaultdict(asyncio.Queue)
         self.payment_preimages = defaultdict(asyncio.Queue)
-        self.localfeatures = (0x08 if request_initial_sync else 0)
+        self.localfeatures = LnLocalFeatures(0)
+        if request_initial_sync:
+            self.localfeatures |= LnLocalFeatures.INITIAL_ROUTING_SYNC
+        self.localfeatures |= LnLocalFeatures.OPTION_DATA_LOSS_PROTECT_OPT
         self.invoices = lnworker.invoices
         self.attempted_route = {}
 
@@ -442,7 +447,17 @@ class Peer(PrintError):
         self.network.trigger_callback('ln_status')
 
     def on_init(self, payload):
-        pass
+        # if they required some even flag we don't have, they will close themselves
+        # but if we require an even flag they don't have, we close
+        our_flags = set(list_enabled_bits(self.localfeatures))
+        their_flags = set(list_enabled_bits(int.from_bytes(payload['localfeatures'], byteorder="big")))
+        for flag in our_flags:
+            if flag not in their_flags and get_ln_flag_pair_of_bit(flag) not in their_flags:
+                # they don't have this feature we wanted :(
+                if flag % 2 == 0:  # even flags are compulsory
+                    raise LightningPeerConnectionClosed("remote does not have even flag {}"
+                                                        .format(str(LnLocalFeatures(1 << flag))))
+                self.localfeatures ^= 1 << flag  # disable flag
 
     def on_channel_update(self, payload):
         try:

electrum/lnrouter.py

@@ -39,7 +39,7 @@ from .storage import JsonDB
 from .lnchannelverifier import LNChannelVerifier, verify_sig_for_channel_update
 from .crypto import Hash
 from . import ecc
-from .lnutil import LN_GLOBAL_FEATURE_BITS, LNPeerAddr
+from .lnutil import LN_GLOBAL_FEATURES_KNOWN_SET, LNPeerAddr
 
 
 class UnknownEvenFeatureBits(Exception): pass
@@ -55,7 +55,7 @@ class ChannelInfo(PrintError):
         self.features = channel_announcement_payload['features']
         enabled_features = list_enabled_bits(int.from_bytes(self.features, "big"))
         for fbit in enabled_features:
-            if fbit not in LN_GLOBAL_FEATURE_BITS and fbit % 2 == 0:
+            if (1 << fbit) not in LN_GLOBAL_FEATURES_KNOWN_SET and fbit % 2 == 0:
                 raise UnknownEvenFeatureBits()
 
         self.channel_id = channel_announcement_payload['short_channel_id']
@@ -191,7 +191,7 @@ class NodeInfo(PrintError):
         self.features = node_announcement_payload['features']
         enabled_features = list_enabled_bits(int.from_bytes(self.features, "big"))
         for fbit in enabled_features:
-            if fbit not in LN_GLOBAL_FEATURE_BITS and fbit % 2 == 0:
+            if (1 << fbit) not in LN_GLOBAL_FEATURES_KNOWN_SET and fbit % 2 == 0:
                 raise UnknownEvenFeatureBits()
         if not addresses_already_parsed:
             self.addresses = self.parse_addresses_field(node_announcement_payload['addresses'])

electrum/lnutil.py

@@ -426,19 +426,36 @@ def get_ecdh(priv: bytes, pub: bytes) -> bytes:
     return sha256(pt.get_public_key_bytes())
 
 
-LN_LOCAL_FEATURE_BITS = {
-    0: 'option_data_loss_protect_req',
-    1: 'option_data_loss_protect_opt',
-    3: 'initial_routing_sync',
-    4: 'option_upfront_shutdown_script_req',
-    5: 'option_upfront_shutdown_script_opt',
-    6: 'gossip_queries_req',
-    7: 'gossip_queries_opt',
-}
-LN_LOCAL_FEATURE_BITS_INV = inv_dict(LN_LOCAL_FEATURE_BITS)
+class LnLocalFeatures(IntFlag):
+    OPTION_DATA_LOSS_PROTECT_REQ = 1 << 0
+    OPTION_DATA_LOSS_PROTECT_OPT = 1 << 1
+    INITIAL_ROUTING_SYNC = 1 << 3
+    OPTION_UPFRONT_SHUTDOWN_SCRIPT_REQ = 1 << 4
+    OPTION_UPFRONT_SHUTDOWN_SCRIPT_OPT = 1 << 5
+    GOSSIP_QUERIES_REQ = 1 << 6
+    GOSSIP_QUERIES_OPT = 1 << 7
 
-LN_GLOBAL_FEATURE_BITS = {}
-LN_GLOBAL_FEATURE_BITS_INV = inv_dict(LN_GLOBAL_FEATURE_BITS)
+# note that these are powers of two, not the bits themselves
+LN_LOCAL_FEATURES_KNOWN_SET = set(LnLocalFeatures)
+
+
+def get_ln_flag_pair_of_bit(flag_bit: int):
+    """Ln Feature flags are assigned in pairs, one even, one odd. See BOLT-09.
+    Return the other flag from the pair.
+    e.g. 6 -> 7
+    e.g. 7 -> 6
+    """
+    if flag_bit % 2 == 0:
+        return flag_bit + 1
+    else:
+        return flag_bit - 1
+
+
+class LnGlobalFeatures(IntFlag):
+    pass
+
+# note that these are powers of two, not the bits themselves
+LN_GLOBAL_FEATURES_KNOWN_SET = set(LnGlobalFeatures)
 
 
 class LNPeerAddr(namedtuple('LNPeerAddr', ['host', 'port', 'pubkey'])):