cln-rpc: Add OutputDesc for {addr: amt} style arguments

This is likely inherited from bitcoind, and a bit awkward for us, so
we parse it into a classic struct, but serialize it back into the
bitcoind format when talking to the RPC.

cln-grpc/proto/primitives.proto

@@ -39,4 +39,9 @@ message Feerate {
 		uint32 perkb = 4;
 		uint32 perkw = 5;
 	}
+}
+
+message OutputDesc {
+	string address = 1;
+	Amount amount = 2;
 }

cln-grpc/src/pb.rs

@@ -1,6 +1,8 @@
 tonic::include_proto!("cln");
 
-use cln_rpc::primitives::{Amount as JAmount, Utxo as JUtxo};
+use cln_rpc::primitives::{
+    Amount as JAmount, Feerate as JFeerate, OutputDesc as JOutputDesc, Utxo as JUtxo,
+};
 
 impl From<JAmount> for Amount {
     fn from(a: JAmount) -> Self {
@@ -34,7 +36,6 @@ impl From<&Utxo> for JUtxo {
 
 impl From<&Feerate> for cln_rpc::primitives::Feerate {
     fn from(f: &Feerate) -> cln_rpc::primitives::Feerate {
-        use cln_rpc::primitives::Feerate as JFeerate;
         use feerate::Style;
         match f.style.clone().unwrap() {
             Style::Slow(_) => JFeerate::Slow,
@@ -45,3 +46,12 @@ impl From<&Feerate> for cln_rpc::primitives::Feerate {
         }
     }
 }
+
+impl From<&OutputDesc> for JOutputDesc {
+    fn from(od: &OutputDesc) -> JOutputDesc {
+        JOutputDesc {
+            address: od.address.clone(),
+            amount: od.amount.as_ref().unwrap().into(),
+        }
+    }
+}

cln-rpc/src/primitives.rs

@@ -368,8 +368,60 @@ mod test {
         for (input, output) in tests.into_iter() {
             let parsed: Feerate = input.try_into().unwrap();
             assert_eq!(parsed, output);
-	    let serialized: String = (&parsed).into();
-	    assert_eq!(serialized, input);
+            let serialized: String = (&parsed).into();
+            assert_eq!(serialized, input);
         }
     }
+
+    #[test]
+    fn test_parse_output_desc() {
+        let a = r#"{"address":"1234msat"}"#;
+        let od = serde_json::from_str(a).unwrap();
+
+        assert_eq!(
+            OutputDesc {
+                address: "address".to_string(),
+                amount: Amount { msat: 1234 }
+            },
+            od
+        );
+        let serialized: String = serde_json::to_string(&od).unwrap();
+        assert_eq!(a, serialized);
+    }
+}
+
+#[derive(Clone, Debug, PartialEq)]
+pub struct OutputDesc {
+    pub address: String,
+    pub amount: Amount,
+}
+
+impl<'de> Deserialize<'de> for OutputDesc {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        let map: std::collections::HashMap<String, Amount> =
+            Deserialize::deserialize(deserializer)?;
+
+        let (address, amount) = map.iter().next().unwrap();
+
+        Ok(OutputDesc {
+            address: address.to_string(),
+            amount: *amount,
+        })
+    }
+}
+
+impl Serialize for OutputDesc {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: Serializer,
+    {
+        use serde::ser::SerializeMap;
+        let mut map = serializer.serialize_map(Some(1))?;
+        map.serialize_key(&self.address)?;
+        map.serialize_value(&self.amount)?;
+        map.end()
+    }
 }

contrib/msggen/msggen/model.py

@@ -232,6 +232,7 @@ class PrimitiveField(Field):
         "number",
         "feerate",
         "utxo",  # A string representing the tuple (txid, outnum)
+        "OutputDesc",  # A dict that maps an address to an amount (bitcoind style)
     ]
 
     def __init__(self, typename, path, description):