Merge pull request #110 from feelancer21/inbound_fees

Inbound fees

README.md

@@ -61,6 +61,20 @@ This policy matches the channels against the `chan.min_capacity` criterium. Only
 
 If a channel matches this policy, the `static` strategy is then used, which takes the `base_fee_msat` and `fee_ppm`  properties defined in the policy and applies them to the channel.
 
+If at least lnd 0.18 is used, charge-lnd also supports the experimental support of inbound fees. By default, lnd only supports negative inbound fees on the inbound channel, which then act as a “discount” on the outbound fees of the outgoing channel. However, the entire forward fee cannot become negative.
+
+Example with inbound fees:
+```
+[example-policy]
+chan.min_capacity = 500000
+
+strategy = static
+base_fee_msat = 1000
+fee_ppm = 2000
+inbound_base_fee_msat = -500
+inbound_fee_ppm = -1000
+```
+
 ### Non-final policies
 
 You can also define a 'non-final' policy. This is simply a policy without a strategy.
@@ -102,6 +116,8 @@ chan.min_capacity = 250000
 strategy = static
 base_fee_msat = 10000
 fee_ppm = 500
+inbound_base_fee_msat = -8000
+inbound_fee_ppm = -400
 
 [encourage-routing-to-balance]
 chan.min_ratio = 0.9
@@ -187,11 +203,11 @@ Available strategies:
 |:--|:--|:--|
 |**ignore** | ignores the channel completely||
 |**ignore_fees** | don't make any fee changes, only update htlc size limits and time_lock_delta||
-|**static** | sets fixed base fee and fee rate values.| **fee_ppm**|
-|**match_peer** | sets the same base fee and fee rate values as the peer|if **base_fee_msat** or **fee_ppm** are set the override the peer values|
+|**static** | sets fixed base fee and fee rate values for the outbound and inbound side.| **fee_ppm**<br>**base_fee_msat**<br>**inbound_fee_ppm**<br>**inbound_base_fee_msat**|
+|**match_peer** | sets the same base fee and fee rate values as the peer for the outbound and inbound side.|if **base_fee_msat**, **fee_ppm**, **inbound_base_fee_msat** or **inbound_fee_ppm**  are set the override the peer values|
 |**cost** | calculate cost for opening channel, and set ppm to cover cost when channel depletes.|**cost_factor**|
 |**onchain_fee** | sets the fees to a % equivalent of a standard onchain payment (Requires --electrum-server to be specified.)| **onchain_fee_btc** BTC<br>within **onchain_fee_numblocks** blocks.|
-|**proportional** | sets fee ppm according to balancedness.|**min_fee_ppm**<br>**max_fee_ppm**<br>**sum_peer_chans** consider all channels with peer for balance calculations|
+|**proportional** | sets outbound fee ppm according to balancedness. Inbound fee ppm keeps unchanged.|**min_fee_ppm**<br>**max_fee_ppm**<br>**sum_peer_chans** consider all channels with peer for balance calculations|
 |**disable** | disables the channel in the outgoing direction. Channel will be re-enabled again if it matches another policy (except when that policy uses an 'ignore' strategy).||
 |**use_config** | process channel according to rules defined in another config file.|**config_file**|
 

charge_lnd/charge_lnd.py

@@ -51,7 +51,7 @@ def main():
         if not policy:
             continue
 
-        (new_base_fee_msat, new_fee_ppm, new_min_htlc, new_max_htlc, new_time_lock_delta, disable) = policy.strategy.execute(channel)
+        (new_base_fee_msat, new_fee_ppm, new_inbound_base_fee_msat, new_inbound_fee_ppm, new_min_htlc, new_max_htlc, new_time_lock_delta, disable) = policy.strategy.execute(channel)
 
         if channel.chan_id in lnd.feereport:
             (current_base_fee_msat, current_fee_ppm) = lnd.feereport[channel.chan_id]
@@ -65,12 +65,16 @@ def main():
         min_fee_ppm_delta = policy.getint('min_fee_ppm_delta',0)
 
         fee_ppm_changed = new_fee_ppm is not None and current_fee_ppm != new_fee_ppm and abs(current_fee_ppm - new_fee_ppm) >= min_fee_ppm_delta
+        inbound_fee_ppm_changed = new_inbound_fee_ppm is not None and my_policy.inbound_fee_rate_milli_msat != new_inbound_fee_ppm and \
+            abs(my_policy.inbound_fee_rate_milli_msat - new_inbound_fee_ppm) >= min_fee_ppm_delta
 
         base_fee_changed = new_base_fee_msat is not None and current_base_fee_msat != new_base_fee_msat
+        inbound_base_fee_changed = new_inbound_base_fee_msat is not None and my_policy.inbound_fee_base_msat != new_inbound_base_fee_msat
         min_htlc_changed = new_min_htlc is not None and my_policy.min_htlc != new_min_htlc
         max_htlc_changed = new_max_htlc is not None and my_policy.max_htlc_msat != new_max_htlc
         time_lock_delta_changed = new_time_lock_delta is not None and my_policy.time_lock_delta != new_time_lock_delta
-        is_changed = fee_ppm_changed or base_fee_changed or min_htlc_changed or max_htlc_changed or time_lock_delta_changed
+        is_changed = fee_ppm_changed or base_fee_changed or min_htlc_changed or max_htlc_changed or \
+            time_lock_delta_changed or inbound_base_fee_changed + inbound_fee_ppm_changed
 
         chan_status_changed = False
         if lnd.min_version(0,13) and channel.active and disable != my_policy.disabled and policy.get('strategy') != 'ignore':
@@ -85,44 +89,57 @@ def main():
                 )
 
         if is_changed and not arguments.dry_run:
-            lnd.update_chan_policy(channel.chan_id, new_base_fee_msat, new_fee_ppm, new_min_htlc, new_max_htlc, new_time_lock_delta)
+            lnd.update_chan_policy(channel.chan_id, new_base_fee_msat, new_fee_ppm, new_min_htlc, 
+                                   new_max_htlc, new_time_lock_delta, new_inbound_base_fee_msat, new_inbound_fee_ppm)
 
         if is_changed or chan_status_changed or arguments.verbose:
-            print("  policy:          %s" % fmt.col_hi(policy.name) )
-            print("  strategy:        %s" % fmt.col_hi(policy.get('strategy')) )
+            print("  policy:                  %s" % fmt.col_hi(policy.name) )
+            print("  strategy:                %s" % fmt.col_hi(policy.get('strategy')) )
             if chan_status_changed or arguments.verbose:
                 s = 'disabled' if my_policy.disabled else 'enabled'
                 if chan_status_changed:
                     s = s + ' ➜ '
                     s = s + 'disabled' if disable else 'enabled'
-                print("  channel status:  %s" % fmt.col_hi(s))
+                print("  channel status:          %s" % fmt.col_hi(s))
             if new_base_fee_msat is not None or arguments.verbose:
                 s = ''
                 if base_fee_changed:
                     s = ' ➜ ' + fmt.col_hi(new_base_fee_msat)
-                print("  base_fee_msat:   %s%s" % (fmt.col_hi(current_base_fee_msat), s) )
+                print("  base_fee_msat:           %s%s" % (fmt.col_hi(current_base_fee_msat), s) )
             if new_fee_ppm is not None or arguments.verbose:
                 s = ''
                 if fee_ppm_changed:
                     s = ' ➜ ' + fmt.col_hi(new_fee_ppm)
                     if min_fee_ppm_delta > abs(new_fee_ppm - current_fee_ppm):
                         s = s + ' (min_fee_ppm_delta=%d)' % min_fee_ppm_delta
-                print("  fee_ppm:         %s%s" % (fmt.col_hi(current_fee_ppm), s) )
+                print("  fee_ppm:                 %s%s" % (fmt.col_hi(current_fee_ppm), s) )
+            if new_inbound_base_fee_msat is not None or arguments.verbose:
+                s = ''
+                if inbound_base_fee_changed:
+                    s = ' ➜ ' + fmt.col_hi(new_inbound_base_fee_msat)
+                print("  inbound_base_fee_msat:   %s%s" % (fmt.col_hi(my_policy.inbound_fee_base_msat), s) )
+            if new_inbound_fee_ppm is not None or arguments.verbose:
+                s = ''
+                if inbound_fee_ppm_changed:
+                    s = ' ➜ ' + fmt.col_hi(new_inbound_fee_ppm)
+                    if min_fee_ppm_delta > abs(new_inbound_fee_ppm - my_policy.inbound_fee_rate_milli_msat):
+                        s = s + ' (min_fee_ppm_delta=%d)' % min_fee_ppm_delta
+                print("  inbound_fee_ppm:         %s%s" % (fmt.col_hi(my_policy.inbound_fee_rate_milli_msat), s) )
             if new_min_htlc is not None or arguments.verbose:
                 s = ''
                 if min_htlc_changed:
                     s = ' ➜ ' + fmt.col_hi(new_min_htlc)
-                print("  min_htlc_msat:   %s%s" % (fmt.col_hi(my_policy.min_htlc), s) )
+                print("  min_htlc_msat:           %s%s" % (fmt.col_hi(my_policy.min_htlc), s) )
             if new_max_htlc is not None or arguments.verbose:
                 s = ''
                 if max_htlc_changed:
                     s = ' ➜ ' + fmt.col_hi(new_max_htlc)
-                print("  max_htlc_msat:   %s%s" % (fmt.col_hi(my_policy.max_htlc_msat), s) )
+                print("  max_htlc_msat:           %s%s" % (fmt.col_hi(my_policy.max_htlc_msat), s) )
             if new_time_lock_delta is not None or arguments.verbose:
                 s = ''
                 if time_lock_delta_changed:
                     s = ' ➜ ' + fmt.col_hi(new_time_lock_delta)
-                print("  time_lock_delta: %s%s" % (fmt.col_hi(my_policy.time_lock_delta), s) )
+                print("  time_lock_delta:         %s%s" % (fmt.col_hi(my_policy.time_lock_delta), s) )
 
     return True