lnutil: turn global forwarding fee params into Channel attributes

useful for unit testing, and it is the conceptually correct thing anyway

electrum/lnchannel.py

@@ -503,6 +503,11 @@ class Channel(AbstractChannel):
     #       they are ambiguous. Use "oldest_unrevoked" or "latest" or "next".
     #       TODO enforce this ^
 
+    # our forwarding parameters for forwarding HTLCs through this channel
+    forwarding_cltv_expiry_delta = 144
+    forwarding_fee_base_msat = 1000
+    forwarding_fee_proportional_millionths = 1
+
     def __init__(self, state: 'StoredDict', *, sweep_address=None, name=None, lnworker=None, initial_feerate=None):
         self.name = name
         Logger.__init__(self)
@@ -600,11 +605,11 @@ class Channel(AbstractChannel):
             short_channel_id=self.short_channel_id,
             channel_flags=channel_flags,
             message_flags=b'\x01',
-            cltv_expiry_delta=lnutil.NBLOCK_OUR_CLTV_EXPIRY_DELTA,
+            cltv_expiry_delta=self.forwarding_cltv_expiry_delta,
             htlc_minimum_msat=self.config[REMOTE].htlc_minimum_msat,
             htlc_maximum_msat=htlc_maximum_msat,
-            fee_base_msat=lnutil.OUR_FEE_BASE_MSAT,
+            fee_base_msat=self.forwarding_fee_base_msat,
-            fee_proportional_millionths=lnutil.OUR_FEE_PROPORTIONAL_MILLIONTHS,
+            fee_proportional_millionths=self.forwarding_fee_proportional_millionths,
             chain_hash=constants.net.rev_genesis_bytes(),
             timestamp=now,
         )

electrum/lnpeer.py

@@ -37,8 +37,7 @@ from .lnutil import (Outpoint, LocalConfig, RECEIVED, UpdateAddHtlc,
                      LOCAL, REMOTE, HTLCOwner,
                      ln_compare_features, privkey_to_pubkey, MIN_FINAL_CLTV_EXPIRY_ACCEPTED,
                      LightningPeerConnectionClosed, HandshakeFailed,
-                     RemoteMisbehaving,
+                     RemoteMisbehaving, ShortChannelID,
-                     NBLOCK_OUR_CLTV_EXPIRY_DELTA, ShortChannelID,
                      IncompatibleLightningFeatures, derive_payment_secret_from_payment_preimage,
                      LN_MAX_FUNDING_SAT, calc_fees_for_commitment_tx,
                      UpfrontShutdownScriptViolation)
@@ -1363,7 +1362,7 @@ class Peer(Logger):
             next_cltv_expiry = processed_onion.hop_data.payload["outgoing_cltv_value"]["outgoing_cltv_value"]
         except:
             raise OnionRoutingFailure(code=OnionFailureCode.INVALID_ONION_PAYLOAD, data=b'\x00\x00\x00')
-        if htlc.cltv_expiry - next_cltv_expiry < NBLOCK_OUR_CLTV_EXPIRY_DELTA:
+        if htlc.cltv_expiry - next_cltv_expiry < next_chan.forwarding_cltv_expiry_delta:
             data = htlc.cltv_expiry.to_bytes(4, byteorder="big") + outgoing_chan_upd_len + outgoing_chan_upd
             raise OnionRoutingFailure(code=OnionFailureCode.INCORRECT_CLTV_EXPIRY, data=data)
         if htlc.cltv_expiry - lnutil.MIN_FINAL_CLTV_EXPIRY_ACCEPTED <= local_height \
@@ -1378,8 +1377,8 @@ class Peer(Logger):
             raise OnionRoutingFailure(code=OnionFailureCode.INVALID_ONION_PAYLOAD, data=b'\x00\x00\x00')
         forwarding_fees = fee_for_edge_msat(
             forwarded_amount_msat=next_amount_msat_htlc,
-            fee_base_msat=lnutil.OUR_FEE_BASE_MSAT,
+            fee_base_msat=next_chan.forwarding_fee_base_msat,
-            fee_proportional_millionths=lnutil.OUR_FEE_PROPORTIONAL_MILLIONTHS)
+            fee_proportional_millionths=next_chan.forwarding_fee_proportional_millionths)
         if htlc.amount_msat - next_amount_msat_htlc < forwarding_fees:
             data = next_amount_msat_htlc.to_bytes(8, byteorder="big") + outgoing_chan_upd_len + outgoing_chan_upd
             raise OnionRoutingFailure(code=OnionFailureCode.FEE_INSUFFICIENT, data=data)

electrum/lnutil.py

@@ -319,11 +319,6 @@ NBLOCK_DEADLINE_AFTER_EXPIRY_FOR_OFFERED_HTLCS = 1
 # the deadline after which the channel has to be failed and the HTLC fulfilled on-chain before its cltv_expiry
 NBLOCK_DEADLINE_BEFORE_EXPIRY_FOR_RECEIVED_HTLCS = 72
 
-# the cltv_expiry_delta for channels when we are forwarding payments
-NBLOCK_OUR_CLTV_EXPIRY_DELTA = 144
-OUR_FEE_BASE_MSAT = 1000
-OUR_FEE_PROPORTIONAL_MILLIONTHS = 1
-
 NBLOCK_CLTV_EXPIRY_TOO_FAR_INTO_FUTURE = 28 * 144
 
 MAXIMUM_REMOTE_TO_SELF_DELAY_ACCEPTED = 2016