Fee handler

modules/ismp/pallets/pallet/src/fee.rs

@@ -0,0 +1,32 @@
+// Copyright (c) 2024 Polytope Labs.
+// SPDX-License-Identifier: Apache-2.0
+
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// 	http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use crate::{weights::get_weight, Config};
+use frame_support::dispatch::{DispatchResultWithPostInfo, Pays, PostDispatchInfo};
+use ismp::messaging::Message;
+
+pub trait HandleFee<T: Config> {
+	fn handle_fee(messages: &[Message], signer: T::AccountId) -> DispatchResultWithPostInfo;
+}
+
+impl<T: Config> HandleFee<T> for () {
+	fn handle_fee(messages: &[Message], _signer: T::AccountId) -> DispatchResultWithPostInfo {
+		//Todo: reward the signer
+		Ok(PostDispatchInfo {
+			actual_weight: Some(get_weight::<T>(&messages)),
+			pays_fee: Pays::Yes,
+		})
+	}
+}

modules/ismp/pallets/pallet/src/impls.rs

@@ -19,12 +19,11 @@ use crate::{
 	child_trie::{RequestCommitments, ResponseCommitments},
 	dispatcher::{FeeMetadata, RequestMetadata},
 	offchain::{self, ForkIdentifier, Leaf, LeafIndexAndPos, OffchainDBProvider, Proof, ProofKeys},
-	weights::get_weight,
 	Config, Error, Event, Pallet, Responded,
 };
 use alloc::{string::ToString, vec, vec::Vec};
 use codec::Decode;
-use frame_support::dispatch::{DispatchResultWithPostInfo, Pays, PostDispatchInfo};
+use frame_support::dispatch::DispatchResult;
 use frame_system::Phase;
 use ismp::{
 	handlers::{handle_incoming_message, MessageResult},
@@ -80,7 +79,7 @@ impl<T: Config> Pallet<T> {
 	}
 
 	/// Execute the provided ISMP datagrams, this will short circuit if any messages are invalid.
-	pub fn execute(messages: Vec<Message>) -> DispatchResultWithPostInfo {
+	pub fn execute(messages: Vec<Message>) -> DispatchResult {
 		// Define a host
 		let host = Pallet::<T>::default();
 		let events = messages
@@ -116,10 +115,7 @@ impl<T: Config> Pallet<T> {
 			Pallet::<T>::deposit_event(event.into())
 		}
 
-		Ok(PostDispatchInfo {
-			actual_weight: Some(get_weight::<T>(&messages)),
-			pays_fee: Pays::Yes,
-		})
+		Ok(())
 	}
 
 	/// Dispatch an outgoing request, returns the request commitment

modules/ismp/pallets/pallet/src/lib.rs

@@ -178,6 +178,7 @@ pub mod child_trie;
 pub mod dispatcher;
 pub mod errors;
 pub mod events;
+mod fee;
 pub mod host;
 mod impls;
 pub mod offchain;
@@ -197,12 +198,13 @@ pub mod pallet {
 	use crate::{
 		child_trie::{RequestCommitments, ResponseCommitments, CHILD_TRIE_PREFIX},
 		errors::HandlingError,
+		fee::HandleFee,
 		weights::{get_weight, WeightProvider},
 	};
 	use codec::{Codec, Encode};
 	use core::fmt::Debug;
 	use frame_support::{
-		dispatch::{DispatchResult, DispatchResultWithPostInfo},
+		dispatch::{DispatchResult, DispatchResultWithPostInfo, PostDispatchInfo},
 		pallet_prelude::*,
 		traits::{fungible::Mutate, tokens::Preservation, Get, UnixTime},
 		PalletId,
@@ -220,13 +222,12 @@ pub mod pallet {
 		router::IsmpRouter,
 	};
 	use sp_core::{storage::ChildInfo, H256};
-	#[cfg(feature = "unsigned")]
-	use sp_runtime::transaction_validity::{
-		InvalidTransaction, TransactionSource, TransactionValidity, TransactionValidityError,
-		ValidTransaction,
-	};
 	use sp_runtime::{
 		traits::{AccountIdConversion, AtLeast32BitUnsigned},
+		transaction_validity::{
+			InvalidTransaction, TransactionSource, TransactionValidity, TransactionValidityError,
+			ValidTransaction,
+		},
 		FixedPointOperand,
 	};
 	use sp_std::prelude::*;
@@ -304,6 +305,9 @@ pub mod pallet {
 		/// This offchain DB is also allowed to "merkelize" and "generate proofs" for messages.
 		/// Most state machines will likey not need this and can just provide `()`
 		type OffchainDB: OffchainDBProvider<Leaf = Leaf>;
+
+		/// FeeHandler with custom fee logic
+		type FeeHandler: HandleFee<Self>;
 	}
 
 	// Simple declaration of the `Pallet` type. It is placeholder we use to implement traits and
@@ -427,7 +431,6 @@ pub mod pallet {
 		/// - `messages`: the messages to handle or process.
 		///
 		/// Emits different message events based on the Message received if successful.
-		#[cfg(feature = "unsigned")]
 		#[pallet::weight(get_weight::<T>(&messages))]
 		#[pallet::call_index(0)]
 		#[frame_support::transactional]
@@ -437,7 +440,12 @@ pub mod pallet {
 		) -> DispatchResultWithPostInfo {
 			ensure_none(origin)?;
 
-			Self::execute(messages)
+			Self::execute(messages.clone())?;
+
+			Ok(PostDispatchInfo {
+				actual_weight: Some(get_weight::<T>(&messages)),
+				pays_fee: Pays::No,
+			})
 		}
 
 		/// Execute the provided batch of ISMP messages. This call will short-circuit and revert if
@@ -448,14 +456,15 @@ pub mod pallet {
 		/// - `messages`: A set of ISMP [`Message`]s to handle or process.
 		///
 		/// Emits different message events based on the Message received if successful.
-		#[cfg(not(feature = "unsigned"))]
 		#[pallet::weight(get_weight::<T>(&messages))]
 		#[pallet::call_index(1)]
 		#[frame_support::transactional]
 		pub fn handle(origin: OriginFor<T>, messages: Vec<Message>) -> DispatchResultWithPostInfo {
-			ensure_signed(origin)?;
+			let signer = ensure_signed(origin)?;
+
+			Self::execute(messages.clone())?;
 
-			Self::execute(messages)
+			T::FeeHandler::handle_fee(messages.as_slice(), signer)
 		}
 
 		/// Create a consensus client, using a subjectively chosen consensus state. This can also
@@ -644,7 +653,6 @@ pub mod pallet {
 	}
 
 	/// This allows users execute ISMP datagrams for free. Use with caution.
-	#[cfg(feature = "unsigned")]
 	#[pallet::validate_unsigned]
 	impl<T: Config> ValidateUnsigned for Pallet<T> {
 		type Call = Call<T>;

parachain/runtimes/nexus/Cargo.toml

@@ -91,7 +91,7 @@ parachains-common = { workspace = true  }
 
 # ismp modules
 ismp = { workspace = true  }
-pallet-ismp = { workspace = true, features = ["unsigned"]  }
+pallet-ismp = { workspace = true }
 pallet-ismp-demo = { workspace = true  }
 pallet-ismp-runtime-api = { workspace = true  }
 ismp-parachain = { workspace = true  }

parachain/runtimes/nexus/src/ismp.rs

@@ -112,6 +112,7 @@ impl pallet_ismp::Config for Runtime {
 	);
 	type OffchainDB = Mmr;
 	type WeightProvider = ();
+	type FeeHandler = ();
 }
 
 impl pallet_ismp_relayer::Config for Runtime {