UIP-5: Outbound PFM support (#4940)

## Describe your changes

Implementation of the candidate UIP-5: outbound PFM support (see
https://forum.penumbra.zone/t/pre-uip-outbound-packet-forwarding-middleware-support/121)

Should be reviewed for correctness and adherence to the spec.

Note that this only includes the required protocol changes to allow
clients to use the new memo field (a prerequisite for PFM support), and
does not implement outbound packet forwarding directly (that is to be
done in the client).


By @avahowell cherry-picked from #4923

Co-authored-by: Ava Howell <[email protected]>

crates/bin/pcli/src/command/tx.rs

@@ -1133,6 +1133,7 @@ impl TxCmd {
                     // TODO: impl From<u64> for ChannelId
                     source_channel: ChannelId::from_str(format!("channel-{}", channel).as_ref())?,
                     use_compat_address: *use_compat_address,
+                    ics20_memo: "".to_string(),
                 };
 
                 let plan = Planner::new(OsRng)

crates/core/app/tests/common/ibc_tests/relayer.rs

@@ -1485,6 +1485,7 @@ impl MockRelayer {
             source_channel: ChannelId::from_str("channel-0")?,
             // Penumbra <-> Penumbra so false
             use_compat_address: false,
+            ics20_memo: "".to_string(),
         };
         // There will need to be `Spend` and `Output` actions
         // within the transaction in order for it to balance

crates/core/component/shielded-pool/src/ics20_withdrawal.rs

@@ -41,6 +41,11 @@ pub struct Ics20Withdrawal {
     // Whether to use a "compat" (bech32, non-m) address for the return address in the withdrawal,
     // for compatability with chains that expect to be able to parse the return address as bech32.
     pub use_compat_address: bool,
+
+    // Arbitrary string data to be included in the `memo` field
+    // of the ICS-20 FungibleTokenPacketData for this withdrawal.
+    // Commonly used for packet forwarding support, or other protocols that may support usage of the memo field.
+    pub ics20_memo: String,
 }
 
 #[cfg(feature = "component")]
@@ -118,6 +123,7 @@ impl From<Ics20Withdrawal> for pb::Ics20Withdrawal {
             timeout_time: w.timeout_time,
             source_channel: w.source_channel.to_string(),
             use_compat_address: w.use_compat_address,
+            ics20_memo: w.ics20_memo.to_string(),
         }
     }
 }
@@ -148,6 +154,7 @@ impl TryFrom<pb::Ics20Withdrawal> for Ics20Withdrawal {
             timeout_time: s.timeout_time,
             source_channel: ChannelId::from_str(&s.source_channel)?,
             use_compat_address: s.use_compat_address,
+            ics20_memo: s.ics20_memo,
         })
     }
 }
@@ -164,7 +171,7 @@ impl From<Ics20Withdrawal> for pb::FungibleTokenPacketData {
             denom: w.denom.to_string(),
             receiver: w.destination_chain_address,
             sender: return_address,
-            memo: "".to_string(),
+            memo: w.ics20_memo,
         }
     }
 }

crates/proto/src/gen/penumbra.core.component.ibc.v1.rs

@@ -73,6 +73,11 @@ pub struct Ics20Withdrawal {
     /// for compatability with chains that expect to be able to parse the return address as bech32.
     #[prost(bool, tag = "8")]
     pub use_compat_address: bool,
+    /// Arbitrary string data to be included in the `memo` field
+    /// of the ICS-20 FungibleTokenPacketData for this withdrawal.
+    /// Commonly used for packet forwarding support, or other protocols that may support usage of the memo field.
+    #[prost(string, tag = "9")]
+    pub ics20_memo: ::prost::alloc::string::String,
 }
 impl ::prost::Name for Ics20Withdrawal {
     const NAME: &'static str = "Ics20Withdrawal";

crates/proto/src/gen/penumbra.core.component.ibc.v1.serde.rs

@@ -1057,6 +1057,9 @@ impl serde::Serialize for Ics20Withdrawal {
         if self.use_compat_address {
             len += 1;
         }
+        if !self.ics20_memo.is_empty() {
+            len += 1;
+        }
         let mut struct_ser = serializer.serialize_struct("penumbra.core.component.ibc.v1.Ics20Withdrawal", len)?;
         if let Some(v) = self.amount.as_ref() {
             struct_ser.serialize_field("amount", v)?;
@@ -1083,6 +1086,9 @@ impl serde::Serialize for Ics20Withdrawal {
         if self.use_compat_address {
             struct_ser.serialize_field("useCompatAddress", &self.use_compat_address)?;
         }
+        if !self.ics20_memo.is_empty() {
+            struct_ser.serialize_field("ics20Memo", &self.ics20_memo)?;
+        }
         struct_ser.end()
     }
 }
@@ -1107,6 +1113,8 @@ impl<'de> serde::Deserialize<'de> for Ics20Withdrawal {
             "sourceChannel",
             "use_compat_address",
             "useCompatAddress",
+            "ics20_memo",
+            "ics20Memo",
         ];
 
         #[allow(clippy::enum_variant_names)]
@@ -1119,6 +1127,7 @@ impl<'de> serde::Deserialize<'de> for Ics20Withdrawal {
             TimeoutTime,
             SourceChannel,
             UseCompatAddress,
+            Ics20Memo,
             __SkipField__,
         }
         impl<'de> serde::Deserialize<'de> for GeneratedField {
@@ -1149,6 +1158,7 @@ impl<'de> serde::Deserialize<'de> for Ics20Withdrawal {
                             "timeoutTime" | "timeout_time" => Ok(GeneratedField::TimeoutTime),
                             "sourceChannel" | "source_channel" => Ok(GeneratedField::SourceChannel),
                             "useCompatAddress" | "use_compat_address" => Ok(GeneratedField::UseCompatAddress),
+                            "ics20Memo" | "ics20_memo" => Ok(GeneratedField::Ics20Memo),
                             _ => Ok(GeneratedField::__SkipField__),
                         }
                     }
@@ -1176,6 +1186,7 @@ impl<'de> serde::Deserialize<'de> for Ics20Withdrawal {
                 let mut timeout_time__ = None;
                 let mut source_channel__ = None;
                 let mut use_compat_address__ = None;
+                let mut ics20_memo__ = None;
                 while let Some(k) = map_.next_key()? {
                     match k {
                         GeneratedField::Amount => {
@@ -1228,6 +1239,12 @@ impl<'de> serde::Deserialize<'de> for Ics20Withdrawal {
                             }
                             use_compat_address__ = Some(map_.next_value()?);
                         }
+                        GeneratedField::Ics20Memo => {
+                            if ics20_memo__.is_some() {
+                                return Err(serde::de::Error::duplicate_field("ics20Memo"));
+                            }
+                            ics20_memo__ = Some(map_.next_value()?);
+                        }
                         GeneratedField::__SkipField__ => {
                             let _ = map_.next_value::<serde::de::IgnoredAny>()?;
                         }
@@ -1242,6 +1259,7 @@ impl<'de> serde::Deserialize<'de> for Ics20Withdrawal {
                     timeout_time: timeout_time__.unwrap_or_default(),
                     source_channel: source_channel__.unwrap_or_default(),
                     use_compat_address: use_compat_address__.unwrap_or_default(),
+                    ics20_memo: ics20_memo__.unwrap_or_default(),
                 })
             }
         }

proto/penumbra/penumbra/core/component/ibc/v1/ibc.proto

@@ -54,6 +54,11 @@ message Ics20Withdrawal {
   // Whether to use a "compat" (bech32, non-m) address for the return address in the withdrawal,
   // for compatability with chains that expect to be able to parse the return address as bech32.
   bool use_compat_address = 8;
+
+  // Arbitrary string data to be included in the `memo` field
+  // of the ICS-20 FungibleTokenPacketData for this withdrawal.
+  // Commonly used for packet forwarding support, or other protocols that may support usage of the memo field.
+  string ics20_memo = 9;
 }
 
 message ClientData {