feerates: add floor field for the current minimum feerate bitcoind will accept

Changelog-Added: JSON-RPC: `feerates`: added `floor` field for current minimum feerate bitcoind will accept
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

.msggen.json

@@ -358,6 +358,7 @@
         "FeeratesPerkb": {
             "Feerates.perkb.delayed_to_us": 6,
             "Feerates.perkb.estimates[]": 9,
+            "Feerates.perkb.floor": 10,
             "Feerates.perkb.htlc_resolution": 7,
             "Feerates.perkb.max_acceptable": 2,
             "Feerates.perkb.min_acceptable": 1,
@@ -374,6 +375,7 @@
         "FeeratesPerkw": {
             "Feerates.perkw.delayed_to_us": 6,
             "Feerates.perkw.estimates[]": 9,
+            "Feerates.perkw.floor": 10,
             "Feerates.perkw.htlc_resolution": 7,
             "Feerates.perkw.max_acceptable": 2,
             "Feerates.perkw.min_acceptable": 1,
@@ -1572,6 +1574,10 @@
             "added": "v23.05",
             "deprecated": false
         },
+        "Feerates.perkb.floor": {
+            "added": "v23.05",
+            "deprecated": false
+        },
         "Feerates.perkb.htlc_resolution": {
             "added": "pre-v0.10.1",
             "deprecated": "v23.05"
@@ -1624,6 +1630,10 @@
             "added": "v23.05",
             "deprecated": false
         },
+        "Feerates.perkw.floor": {
+            "added": "v23.05",
+            "deprecated": false
+        },
         "Feerates.perkw.htlc_resolution": {
             "added": "pre-v0.10.1",
             "deprecated": "v23.05"

cln-grpc/proto/node.proto

@@ -1130,6 +1130,7 @@ message FeeratesResponse {
 message FeeratesPerkb {
 	uint32 min_acceptable = 1;
 	uint32 max_acceptable = 2;
+	optional uint32 floor = 10;
 	repeated FeeratesPerkbEstimates estimates = 9;
 	optional uint32 opening = 3;
 	optional uint32 mutual_close = 4;
@@ -1148,6 +1149,7 @@ message FeeratesPerkbEstimates {
 message FeeratesPerkw {
 	uint32 min_acceptable = 1;
 	uint32 max_acceptable = 2;
+	optional uint32 floor = 10;
 	repeated FeeratesPerkwEstimates estimates = 9;
 	optional uint32 opening = 3;
 	optional uint32 mutual_close = 4;

cln-grpc/src/convert.rs

@@ -932,6 +932,7 @@ impl From<responses::FeeratesPerkb> for pb::FeeratesPerkb {
         Self {
             min_acceptable: c.min_acceptable, // Rule #2 for type u32
             max_acceptable: c.max_acceptable, // Rule #2 for type u32
+            floor: c.floor, // Rule #2 for type u32?
             estimates: c.estimates.map(|arr| arr.into_iter().map(|i| i.into()).collect()).unwrap_or(vec![]), // Rule #3
             opening: c.opening, // Rule #2 for type u32?
             mutual_close: c.mutual_close, // Rule #2 for type u32?
@@ -962,6 +963,7 @@ impl From<responses::FeeratesPerkw> for pb::FeeratesPerkw {
         Self {
             min_acceptable: c.min_acceptable, // Rule #2 for type u32
             max_acceptable: c.max_acceptable, // Rule #2 for type u32
+            floor: c.floor, // Rule #2 for type u32?
             estimates: c.estimates.map(|arr| arr.into_iter().map(|i| i.into()).collect()).unwrap_or(vec![]), // Rule #3
             opening: c.opening, // Rule #2 for type u32?
             mutual_close: c.mutual_close, // Rule #2 for type u32?
@@ -3297,6 +3299,7 @@ impl From<pb::FeeratesPerkb> for responses::FeeratesPerkb {
         Self {
             min_acceptable: c.min_acceptable, // Rule #1 for type u32
             max_acceptable: c.max_acceptable, // Rule #1 for type u32
+            floor: c.floor, // Rule #1 for type u32?
             estimates: Some(c.estimates.into_iter().map(|s| s.into()).collect()), // Rule #4
             opening: c.opening, // Rule #1 for type u32?
             mutual_close: c.mutual_close, // Rule #1 for type u32?
@@ -3325,6 +3328,7 @@ impl From<pb::FeeratesPerkw> for responses::FeeratesPerkw {
         Self {
             min_acceptable: c.min_acceptable, // Rule #1 for type u32
             max_acceptable: c.max_acceptable, // Rule #1 for type u32
+            floor: c.floor, // Rule #1 for type u32?
             estimates: Some(c.estimates.into_iter().map(|s| s.into()).collect()), // Rule #4
             opening: c.opening, // Rule #1 for type u32?
             mutual_close: c.mutual_close, // Rule #1 for type u32?

cln-rpc/src/model.rs

@@ -3231,6 +3231,8 @@ pub mod responses {
 	pub struct FeeratesPerkb {
 	    pub min_acceptable: u32,
 	    pub max_acceptable: u32,
+	    #[serde(skip_serializing_if = "Option::is_none")]
+	    pub floor: Option<u32>,
 	    #[serde(skip_serializing_if = "crate::is_none_or_empty")]
 	    pub estimates: Option<Vec<FeeratesPerkbEstimates>>,
 	    #[serde(skip_serializing_if = "Option::is_none")]
@@ -3263,6 +3265,8 @@ pub mod responses {
 	pub struct FeeratesPerkw {
 	    pub min_acceptable: u32,
 	    pub max_acceptable: u32,
+	    #[serde(skip_serializing_if = "Option::is_none")]
+	    pub floor: Option<u32>,
 	    #[serde(skip_serializing_if = "crate::is_none_or_empty")]
 	    pub estimates: Option<Vec<FeeratesPerkwEstimates>>,
 	    #[serde(skip_serializing_if = "Option::is_none")]

contrib/pyln-testing/pyln/testing/grpc2py.py

@@ -741,6 +741,7 @@ def feerates_perkb2py(m):
     return remove_default({
         "min_acceptable": m.min_acceptable,  # PrimitiveField in generate_composite
         "max_acceptable": m.max_acceptable,  # PrimitiveField in generate_composite
+        "floor": m.floor,  # PrimitiveField in generate_composite
         "estimates": [feerates_perkb_estimates2py(i) for i in m.estimates],  # ArrayField[composite] in generate_composite
         "opening": m.opening,  # PrimitiveField in generate_composite
         "mutual_close": m.mutual_close,  # PrimitiveField in generate_composite
@@ -763,6 +764,7 @@ def feerates_perkw2py(m):
     return remove_default({
         "min_acceptable": m.min_acceptable,  # PrimitiveField in generate_composite
         "max_acceptable": m.max_acceptable,  # PrimitiveField in generate_composite
+        "floor": m.floor,  # PrimitiveField in generate_composite
         "estimates": [feerates_perkw_estimates2py(i) for i in m.estimates],  # ArrayField[composite] in generate_composite
         "opening": m.opening,  # PrimitiveField in generate_composite
         "mutual_close": m.mutual_close,  # PrimitiveField in generate_composite

doc/lightning-feerates.7.md

@@ -50,6 +50,7 @@ On success, an object is returned, containing:
 - **perkb** (object, optional): If *style* parameter was perkb:
   - **min\_acceptable** (u32): The smallest feerate that we allow peers to specify: half the 100-block estimate
   - **max\_acceptable** (u32): The largest feerate we will accept from remote negotiations.  If a peer attempts to set the feerate higher than this we will unilaterally close the channel (or simply forget it if it's not open yet).
+  - **floor** (u32): The smallest feerate that our backend tells us it will accept (i.e. minrelayfee or mempoolminfee) *(added v23.05)*
   - **estimates** (array of objects): Feerate estimates from plugin which we are using (usuallly bcli) *(added v23.05)*:
     - **blockcount** (u32): The number of blocks the feerate is expected to get a transaction in *(added v23.05)*
     - **feerate** (u32): The feerate for this estimate, in given *style* *(added v23.05)*
@@ -63,6 +64,7 @@ On success, an object is returned, containing:
 - **perkw** (object, optional): If *style* parameter was perkw:
   - **min\_acceptable** (u32): The smallest feerate that you can use, usually the minimum relayed feerate of the backend
   - **max\_acceptable** (u32): The largest feerate we will accept from remote negotiations.  If a peer attempts to set the feerate higher than this we will unilaterally close the channel (or simply forget it if it's not open yet).
+  - **floor** (u32): The smallest feerate that our backend tells us it will accept (i.e. minrelayfee or mempoolminfee) *(added v23.05)*
   - **estimates** (array of objects): Feerate estimates from plugin which we are using (usuallly bcli) *(added v23.05)*:
     - **blockcount** (u32): The number of blocks the feerate is expected to get a transaction in *(added v23.05)*
     - **feerate** (u32): The feerate for this estimate, in given *style* *(added v23.05)*
@@ -136,4 +138,4 @@ RESOURCES
 
 Main web site: <https://github.com/ElementsProject/lightning>
 
-[comment]: # ( SHA256STAMP:c21d903c29fd6195d5890962eaa3265a26a57885b95714696916bd32168b66bc)
+[comment]: # ( SHA256STAMP:4921275aec48da8b9ddcba5d4237efa72f06b6e005008f2c3aa7029d3bd187fd)

doc/schemas/feerates.schema.json

@@ -15,6 +15,7 @@
       "required": [
         "min_acceptable",
         "max_acceptable",
+        "floor",
         "estimates"
       ],
       "properties": {
@@ -26,6 +27,11 @@
           "type": "u32",
           "description": "The largest feerate we will accept from remote negotiations.  If a peer attempts to set the feerate higher than this we will unilaterally close the channel (or simply forget it if it's not open yet)."
         },
+        "floor": {
+          "type": "u32",
+          "added": "v23.05",
+          "description": "The smallest feerate that our backend tells us it will accept (i.e. minrelayfee or mempoolminfee)"
+        },
         "estimates": {
           "type": "array",
           "added": "v23.05",
@@ -92,6 +98,7 @@
       "required": [
         "min_acceptable",
         "max_acceptable",
+        "floor",
         "estimates"
       ],
       "properties": {
@@ -103,6 +110,11 @@
           "type": "u32",
           "description": "The largest feerate we will accept from remote negotiations.  If a peer attempts to set the feerate higher than this we will unilaterally close the channel (or simply forget it if it's not open yet)."
         },
+        "floor": {
+          "type": "u32",
+          "added": "v23.05",
+          "description": "The smallest feerate that our backend tells us it will accept (i.e. minrelayfee or mempoolminfee)"
+        },
         "estimates": {
           "type": "array",
           "added": "v23.05",

lightningd/chaintopology.c

@@ -667,6 +667,9 @@ static struct command_result *json_feerates(struct command *cmd,
 		     feerate_to_style(feerate_min(cmd->ld, NULL), *style));
 	json_add_u64(response, "max_acceptable",
 		     feerate_to_style(feerate_max(cmd->ld, NULL), *style));
+	json_add_u64(response, "floor",
+		     feerate_to_style(get_feerate_floor(cmd->ld->topology),
+				      *style));
 
 	json_array_start(response, "estimates");
 	assert(tal_count(topo->smoothed_feerates) == tal_count(topo->feerates[0]));

tests/test_misc.py

@@ -1532,13 +1532,14 @@ def test_feerates(node_factory):
             feerate = l1.rpc.parsefeerate(t)
 
     # Query feerates (shouldn't give any!)
-    wait_for(lambda: len(l1.rpc.feerates('perkw')['perkw']) == 3)
+    wait_for(lambda: len(l1.rpc.feerates('perkw')['perkw']) == 4)
     feerates = l1.rpc.feerates('perkw')
     assert feerates['warning_missing_feerates'] == 'Some fee estimates unavailable: bitcoind startup?'
     assert 'perkb' not in feerates
     assert feerates['perkw']['max_acceptable'] == 2**32 - 1
     assert feerates['perkw']['min_acceptable'] == 253
     assert feerates['perkw']['min_acceptable'] == 253
+    assert feerates['perkw']['floor'] == 253
     assert feerates['perkw']['estimates'] == []
     for t in types:
         assert t not in feerates['perkw']
@@ -1548,6 +1549,8 @@ def test_feerates(node_factory):
     assert 'perkw' not in feerates
     assert feerates['perkb']['max_acceptable'] == (2**32 - 1)
     assert feerates['perkb']['min_acceptable'] == 253 * 4
+    # Note: This is floored at the FEERATE_FLOOR constant (253)
+    assert feerates['perkb']['floor'] == 1012
     assert feerates['perkb']['estimates'] == []
     for t in types:
         assert t not in feerates['perkb']
@@ -1955,6 +1958,7 @@ def test_bitcoind_feerate_floor(node_factory, bitcoind):
             "penalty": 30000,
             "min_acceptable": 7500,
             "max_acceptable": 600000,
+            "floor": 1012,
             "estimates": [{"blockcount": 2,
                            "feerate": 60000,
                            "smoothed_feerate": 60000},
@@ -1993,6 +1997,7 @@ def test_bitcoind_feerate_floor(node_factory, bitcoind):
             # This has increased (rounded up)
             "min_acceptable": 20004,
             "max_acceptable": 600000,
+            "floor": 20004,
             "estimates": [{"blockcount": 2,
                            "feerate": 60000,
                            "smoothed_feerate": 60000},
@@ -2034,6 +2039,7 @@ def test_bitcoind_feerate_floor(node_factory, bitcoind):
             # This has increased (rounded up)
             "min_acceptable": 30004,
             "max_acceptable": 600000,
+            "floor": 30004,
             "estimates": [{"blockcount": 2,
                            "feerate": 60000,
                            "smoothed_feerate": 60000},
@@ -2987,7 +2993,8 @@ def test_force_feerates(node_factory):
         "penalty": 1111,
         "min_acceptable": 1875,
         "max_acceptable": 150000,
-        "estimates": estimates}
+        "estimates": estimates,
+        "floor": 253}
 
     l1.stop()
     l1.daemon.opts['force-feerates'] = '1111/2222'
@@ -3001,7 +3008,8 @@ def test_force_feerates(node_factory):
         "penalty": 2222,
         "min_acceptable": 1875,
         "max_acceptable": 150000,
-        "estimates": estimates}
+        "estimates": estimates,
+        "floor": 253}
 
     l1.stop()
     l1.daemon.opts['force-feerates'] = '1111/2222/3333/4444/5555/6666'
@@ -3015,7 +3023,8 @@ def test_force_feerates(node_factory):
         "penalty": 6666,
         "min_acceptable": 1875,
         "max_acceptable": 150000,
-        "estimates": estimates}
+        "estimates": estimates,
+        "floor": 253}
 
 
 def test_datastore_escapeing(node_factory):