Update fee hysteresis

doc/getting-started/getting-started/configuration.md

@@ -313,6 +313,11 @@ The [`lightning-listconfigs`](ref:lightning-listconfigs) command will output a v
   The percentage of _estimatesmartfee 2/CONSERVATIVE_ to use for the commitment  
   transactions: default is 100.
 
+- **commit-feerate-offset**=_INTEGER_
+
+  The additional feerate a channel opener adds to their preferred feerate to
+  lessen the odds of a disconnect due to feerate disagreement (default 5).
+
 - **max-concurrent-htlcs**=_INTEGER_
 
   Number of HTLCs one channel can handle concurrently in each direction.  

doc/lightning-listconfigs.7.md

@@ -281,6 +281,9 @@ On success, an object is returned, containing:
   - **commit-fee** (object, optional):
     - **value\_int** (u64): field from config or cmdline, or default
     - **source** (string): source of configuration setting
+  - **commit-feerate-offset** (object, optional):
+    - **value\_int** (u32): field from config or cmdline, or default
+    - **source** (string): source of configuration setting
 - **# version** (string, optional): Special field indicating the current version **deprecated, removal in v24.05**
 - **plugins** (array of objects, optional) **deprecated, removal in v24.05**:
   - **path** (string): Full path of the plugin
@@ -359,6 +362,7 @@ On success, an object is returned, containing:
 - **developer** (boolean, optional): Whether developer mode is enabled *(added v23.08)*
 - **commit-fee** (u64, optional): The percentage of the 6-block fee estimate to use for commitment transactions **deprecated, removal in v24.05** *(added v23.05)*
 - **min-emergency-msat** (msat, optional): field from config or cmdline, or default *(added v23.08)*
+- **commit-feerate-offset** (u32, optional): additional commitment feerate applied by channel owner *(added v23.11)*
 
 [comment]: # (GENERATE-FROM-SCHEMA-END)
 
@@ -476,4 +480,4 @@ RESOURCES
 
 Main web site: <https://github.com/ElementsProject/lightning>
 
-[comment]: # ( SHA256STAMP:cc7b6d10f93b9efb34ad76d0cc2273d29189a8dd7ef4acef2e5227755c279ea8)
+[comment]: # ( SHA256STAMP:245e056bdda7c8015917c89e243a0fd3bdd1512ca760da5d7f0a284cb3214ef7)

doc/lightningd-config.5.md

@@ -420,6 +420,11 @@ opens a channel before the channel is usable.
   The percentage of *estimatesmartfee 2/CONSERVATIVE* to use for the commitment
 transactions: default is 100.
 
+* **commit-feerate-offset**=*INTEGER*
+
+  The additional feerate a channel opener adds to their preferred feerate to
+lessen the odds of a disconnect due to feerate disagreement (default 5).
+
 * **max-concurrent-htlcs**=*INTEGER*
 
   Number of HTLCs one channel can handle concurrently in each direction.

doc/schemas/listconfigs.schema.json

@@ -1351,6 +1351,24 @@
               "description": "source of configuration setting"
             }
           }
+        },
+        "commit-feerate-offset": {
+          "type": "object",
+          "additionalProperties": false,
+          "required": [
+            "value_int",
+            "source"
+          ],
+          "properties": {
+            "value_int": {
+              "type": "u32",
+              "description": "field from config or cmdline, or default"
+            },
+            "source": {
+              "type": "string",
+              "description": "source of configuration setting"
+            }
+          }
         }
       }
     },
@@ -1770,6 +1788,11 @@
       "type": "msat",
       "added": "v23.08",
       "description": "field from config or cmdline, or default"
+    },
+    "commit-feerate-offset": {
+      "type": "u32",
+      "added": "v23.11",
+      "description": "additional commitment feerate applied by channel owner"
     }
   }
 }

lightningd/channel_control.c

@@ -56,6 +56,13 @@ void channel_update_feerates(struct lightningd *ld, const struct channel *channe
 	else
 		min_feerate = feerate_min(ld, NULL);
 	max_feerate = feerate_max(ld, NULL);
+	/* The channel opener should use a slightly higher than minimal feerate
+	 * in order to avoid excessive feerate disagreements */
+	if (channel->opener == LOCAL) {
+		feerate += ld->config.feerate_offset;
+		if (feerate > max_feerate)
+			feerate = max_feerate;
+	}
 
 	if (channel->ignore_fee_limits || ld->config.ignore_fee_limits) {
 		min_feerate = 1;

lightningd/lightningd.h

@@ -93,6 +93,9 @@ struct config {
 
 	/* Percent of CONSERVATIVE/2 feerate we'll use for commitment txs. */
 	u64 commit_fee_percent;
+
+	/* Commit feerate offset above min_feerate to use as a channel opener */
+	u32 feerate_offset;
 };
 
 typedef STRMAP(const char *) alt_subdaemon_map;

lightningd/options.c

@@ -948,6 +948,7 @@ static const struct config testnet_config = {
 
 	.max_fee_multiplier = 10,
 	.commit_fee_percent = 100,
+	.feerate_offset = 5,
 };
 
 /* aka. "Dude, where's my coins?" */
@@ -1022,6 +1023,7 @@ static const struct config mainnet_config = {
 
 	.max_fee_multiplier = 10,
 	.commit_fee_percent = 100,
+	.feerate_offset = 5,
 };
 
 static void check_config(struct lightningd *ld)
@@ -1576,6 +1578,10 @@ static void register_opts(struct lightningd *ld)
 	clnopt_witharg("--commit-fee", OPT_SHOWINT,
 		       opt_set_u64, opt_show_u64, &ld->config.commit_fee_percent,
 		       "Percentage of fee to request for their commitment");
+	clnopt_witharg("--commit-feerate-offset", OPT_SHOWINT,
+		       opt_set_u32, opt_show_u32, &ld->config.feerate_offset,
+		       "Additional feerate per kw to apply to feerate updates "
+		       "as the channel opener");
 	clnopt_witharg("--min-emergency-msat", OPT_SHOWMSATS,
 		       opt_set_sat_nondust, opt_show_sat, &ld->emergency_sat,
 		       "Amount to leave in wallet for spending anchor closes");

tests/test_closing.py

@@ -1251,7 +1251,7 @@ def test_penalty_htlc_tx_fulfill(node_factory, bitcoind, chainparams, anchors):
 
     # reconnect with l1, which will fulfill the payment
     l2.rpc.connect(l1.info['id'], 'localhost', l1.port)
-    l2.daemon.wait_for_log('got commitsig .*: feerate 11000, blockheight: 0, 0 added, 1 fulfilled, 0 failed, 0 changed')
+    l2.daemon.wait_for_log('got commitsig .*: feerate 11005, blockheight: 0, 0 added, 1 fulfilled, 0 failed, 0 changed')
 
     # l2 moves on for closed l3
     bitcoind.generate_block(1)
@@ -1463,7 +1463,7 @@ def test_penalty_htlc_tx_timeout(node_factory, bitcoind, chainparams, anchors):
 
     # reconnect with l1, which will fulfill the payment
     l2.rpc.connect(l1.info['id'], 'localhost', l1.port)
-    l2.daemon.wait_for_log('got commitsig .*: feerate {}, blockheight: 0, 0 added, 1 fulfilled, 0 failed, 0 changed'.format(3750 if anchors else 11000))
+    l2.daemon.wait_for_log('got commitsig .*: feerate {}, blockheight: 0, 0 added, 1 fulfilled, 0 failed, 0 changed'.format(3755 if anchors else 11005))
 
     # l2 moves on for closed l3
     bitcoind.generate_block(1, wait_for_mempool=1)
@@ -2650,12 +2650,12 @@ def test_onchain_different_fees(node_factory, bitcoind, executor):
 
     # Both sides should have correct feerate
     assert l1.db_query('SELECT min_possible_feerate, max_possible_feerate FROM channels;') == [{
-        'min_possible_feerate': 5000,
-        'max_possible_feerate': 11000
+        'min_possible_feerate': 5005,
+        'max_possible_feerate': 11005
     }]
     assert l2.db_query('SELECT min_possible_feerate, max_possible_feerate FROM channels;') == [{
-        'min_possible_feerate': 5000,
-        'max_possible_feerate': 11000
+        'min_possible_feerate': 5005,
+        'max_possible_feerate': 11005
     }]
 
     bitcoind.generate_block(5)

tests/test_connection.py

@@ -2412,7 +2412,7 @@ def test_update_fee(node_factory, bitcoind):
     # Make payments.
     l1.pay(l2, 200000000)
     # First payment causes fee update.
-    l2.daemon.wait_for_log('peer updated fee to 11000')
+    l2.daemon.wait_for_log('peer updated fee to 11005')
     l2.pay(l1, 100000000)
 
     # Now shutdown cleanly.
@@ -2454,22 +2454,22 @@ def test_fee_limits(node_factory, bitcoind):
     l1.set_feerates((15, 15, 15, 15), False)
     l1.start()
 
-    l1.daemon.wait_for_log('Received WARNING .*: update_fee 253 outside range 1875-75000')
+    l1.daemon.wait_for_log('Received WARNING .*: update_fee 258 outside range 1875-75000')
     # They hang up on *us*
     l1.daemon.wait_for_log('Peer transient failure in CHANNELD_NORMAL: channeld: Owning subdaemon channeld died')
 
     # Disconnects, but does not error.  Make sure it's noted in their status though.
     # FIXME: does not happen for l1!
     # assert 'update_fee 253 outside range 1875-75000' in only_one(l1.rpc.listpeerchannels(l2.info['id'])['channels'])['status'][0]
-    assert 'update_fee 253 outside range 1875-75000' in only_one(l2.rpc.listpeerchannels(l1.info['id'])['channels'])['status'][0]
+    assert 'update_fee 258 outside range 1875-75000' in only_one(l2.rpc.listpeerchannels(l1.info['id'])['channels'])['status'][0]
 
-    assert only_one(l2.rpc.listpeerchannels()['channels'])['feerate']['perkw'] != 253
+    assert only_one(l2.rpc.listpeerchannels()['channels'])['feerate']['perkw'] != 258
     # Make l2 accept those fees, and it should recover.
     assert only_one(l2.rpc.setchannel(l1.get_channel_scid(l2), ignorefeelimits=True)['channels'])['ignore_fee_limits'] is True
     assert only_one(l2.rpc.listpeerchannels()['channels'])['ignore_fee_limits'] is True
 
     # Now we stay happy (and connected!)
-    wait_for(lambda: only_one(l2.rpc.listpeerchannels()['channels'])['feerate']['perkw'] == 253)
+    wait_for(lambda: only_one(l2.rpc.listpeerchannels()['channels'])['feerate']['perkw'] == 258)
     assert only_one(l2.rpc.listpeerchannels()['channels'])['peer_connected'] is True
 
     l1.rpc.close(l2.info['id'])
@@ -2583,19 +2583,19 @@ def test_update_fee_reconnect(node_factory, bitcoind):
     # Make l1 send out feechange; triggers disconnect/reconnect.
     # (Note: < 10% change, so no smoothing here!)
     l1.set_feerates((14000, 14000, 14000, 3750))
-    l1.daemon.wait_for_log('Setting REMOTE feerate to 14000')
-    l2.daemon.wait_for_log('Setting LOCAL feerate to 14000')
+    l1.daemon.wait_for_log('Setting REMOTE feerate to 14005')
+    l2.daemon.wait_for_log('Setting LOCAL feerate to 14005')
     l1.daemon.wait_for_log(r'dev_disconnect: \+WIRE_COMMITMENT_SIGNED')
 
     # Wait for reconnect....
-    l1.daemon.wait_for_log('Feerate:.*LOCAL now 14000')
+    l1.daemon.wait_for_log('Feerate:.*LOCAL now 14005')
 
     l1.pay(l2, 200000000)
     l2.pay(l1, 100000000)
 
     # They should both have gotten commits with correct feerate.
-    assert l1.daemon.is_in_log('got commitsig [0-9]*: feerate 14000')
-    assert l2.daemon.is_in_log('got commitsig [0-9]*: feerate 14000')
+    assert l1.daemon.is_in_log('got commitsig [0-9]*: feerate 14005')
+    assert l2.daemon.is_in_log('got commitsig [0-9]*: feerate 14005')
 
     # Now shutdown cleanly.
     l1.rpc.close(chan)
@@ -3347,7 +3347,7 @@ def test_feerate_spam(node_factory, chainparams):
     l1.pay(l2, 10**9 - slack)
 
     # It will send this once (may have happened before line_graph's wait)
-    wait_for(lambda: l1.daemon.is_in_log('Setting REMOTE feerate to 11000'))
+    wait_for(lambda: l1.daemon.is_in_log('Setting REMOTE feerate to 11005'))
     wait_for(lambda: l1.daemon.is_in_log('peer_out WIRE_UPDATE_FEE'))
 
     # Now change feerates to something l1 can't afford.

tests/test_misc.py

@@ -3831,3 +3831,30 @@ def test_even_sendcustommsg(node_factory):
     l2.daemon.wait_for_log(r'\[IN\] {}'.format(msg))
     l1.daemon.wait_for_log('Invalid unknown even msg')
     wait_for(lambda: l1.rpc.listpeers(l2.info['id'])['peers'] == [])
+
+
+def test_set_feerate_offset(node_factory, bitcoind):
+    opts = [{'commit-feerate-offset': 100}, {}]
+    l1, l2 = node_factory.get_nodes(2, opts=opts)
+    assert l1.daemon.is_in_log('Server started with public key')
+    configs = l1.rpc.listconfigs()['configs']
+    assert configs['commit-feerate-offset'] == {'source': 'cmdline',
+                                                'value_int': 100}
+    scid12 = l1.fundchannel(l2)[0]
+    # chanid = l1.get_channel_scid(l2)
+
+    # node 1 sets fees.
+    l1.set_feerates((14000, 11000, 7500, 3750))
+
+    l1.pay(l2, 200000000)
+    # First payment causes fee update, which should reflect the feerate offset.
+    l1.daemon.wait_for_log('lightningd: update_feerates: feerate = 11100, '
+                           'min=1875, max=150000, penalty=7500')
+    l2.daemon.wait_for_log('peer updated fee to 11100')
+    l2.pay(l1, 100000000)
+
+    # Now shutdown cleanly.
+    l1.rpc.close(scid12)
+
+    l1.daemon.wait_for_log(' to CLOSINGD_COMPLETE')
+    l2.daemon.wait_for_log(' to CLOSINGD_COMPLETE')