Economic Protocol scenario 3 - "contract earns fee"

Cargo.toml

@@ -6,6 +6,7 @@ members = [
     # Test contracts
     "contracts/alice",
     "contracts/bob",
+    "contracts/charlie",
     "contracts/host_fn",
 
     # Genesis contracts

contracts/Makefile

@@ -1,4 +1,4 @@
-SUBDIRS := alice bob license transfer stake host_fn
+SUBDIRS := alice bob charlie license transfer stake host_fn
 
 all: $(SUBDIRS) ## Build all the contracts
 

contracts/charlie/Cargo.toml

@@ -0,0 +1,15 @@
+[package]
+name = "charlie"
+version = "0.3.0"
+edition = "2021"
+resolver = "2"
+
+[lib]
+crate-type = ["cdylib", "rlib"]
+
+[dependencies]
+execution-core = { version = "0.1.0", path = "../../execution-core" }
+rusk-abi = { version = "0.13.0-rc", path = "../../rusk-abi", features = ["dlmalloc"] }
+rkyv = { version = "0.7", default-features = false, features = ["size_32"] }
+bytecheck = { version = "0.6", default-features = false }
+dusk-bytes = "0.1"

contracts/charlie/Makefile

@@ -0,0 +1,18 @@
+TARGET_DIR:="../../target/dusk"
+
+all: wasm
+
+wasm: ## Generate the optimized WASM for the contract given
+	@RUSTFLAGS="$(RUSTFLAGS) --remap-path-prefix $(HOME)= -C link-args=-zstack-size=65536" \
+	CARGO_TARGET_DIR=$(TARGET_DIR) \
+    	cargo +dusk build \
+    		--release \
+    		--color=always \
+    		-Z build-std=core,alloc,panic_abort \
+    		-Z build-std-features=panic_immediate_abort \
+    		--target wasm32-unknown-unknown
+clippy: 
+
+test:
+
+.PHONY: all test wasm

contracts/charlie/src/lib.rs

@@ -0,0 +1,63 @@
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+//
+// Copyright (c) DUSK NETWORK. All rights reserved.
+
+#![no_std]
+#![feature(arbitrary_self_types)]
+
+extern crate alloc;
+
+mod state;
+use state::Charlie;
+
+#[cfg(target_family = "wasm")]
+#[path = ""]
+mod wasm {
+    use super::*;
+
+    use rusk_abi::{ContractId, PaymentInfo};
+
+    #[no_mangle]
+    static SELF_ID: ContractId = ContractId::uninitialized();
+
+    static mut STATE: Charlie = Charlie;
+
+    #[no_mangle]
+    unsafe fn pay(arg_len: u32) -> u32 {
+        rusk_abi::wrap_call(arg_len, |()| STATE.pay())
+    }
+
+    #[no_mangle]
+    unsafe fn pay_and_fail(arg_len: u32) -> u32 {
+        rusk_abi::wrap_call(arg_len, |()| STATE.pay_and_fail())
+    }
+
+    #[no_mangle]
+    unsafe fn earn(arg_len: u32) -> u32 {
+        rusk_abi::wrap_call(arg_len, |()| STATE.earn())
+    }
+
+    #[no_mangle]
+    unsafe fn earn_and_fail(arg_len: u32) -> u32 {
+        rusk_abi::wrap_call(arg_len, |()| STATE.earn_and_fail())
+    }
+
+    #[no_mangle]
+    unsafe fn earn_indirectly_and_fail(arg_len: u32) -> u32 {
+        rusk_abi::wrap_call(arg_len, |()| STATE.earn_indirectly_and_fail())
+    }
+
+    #[no_mangle]
+    unsafe fn subsidize(arg_len: u32) -> u32 {
+        rusk_abi::wrap_call(arg_len, |arg| STATE.subsidize(arg))
+    }
+
+    const PAYMENT_INFO: PaymentInfo = PaymentInfo::Any(None);
+
+    #[no_mangle]
+    fn payment_info(arg_len: u32) -> u32 {
+        rusk_abi::wrap_call(arg_len, |_: ()| PAYMENT_INFO)
+    }
+}

contracts/charlie/src/state.rs

@@ -0,0 +1,130 @@
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+//
+// Copyright (c) DUSK NETWORK. All rights reserved.
+
+use alloc::vec::Vec;
+use dusk_bytes::Serializable;
+use execution_core::transfer::Stct;
+use execution_core::{BlsPublicKey, BlsSignature};
+use rkyv::{Archive, Deserialize, Serialize};
+use rusk_abi::TRANSFER_CONTRACT;
+
+#[derive(Debug, Clone)]
+pub struct Charlie;
+
+/// Subsidy a contract with a value.
+#[derive(Debug, Clone, PartialEq, Eq, Archive, Serialize, Deserialize)]
+#[archive_attr(derive(bytecheck::CheckBytes))]
+pub struct Subsidy {
+    /// Public key to which the subsidy will belong.
+    pub public_key: BlsPublicKey,
+    /// Signature belonging to the given public key.
+    pub signature: BlsSignature,
+    /// Value of the subsidy.
+    pub value: u64,
+    /// Proof of the `STCT` circuit.
+    pub proof: Vec<u8>,
+}
+
+const SUBSIDY_MESSAGE_SIZE: usize = u64::SIZE + u64::SIZE;
+
+/// Return the digest to be signed in the `subsidize` function of a contract.
+#[must_use]
+pub fn subsidy_signature_message(
+    counter: u64,
+    value: u64,
+) -> [u8; SUBSIDY_MESSAGE_SIZE] {
+    let mut bytes = [0u8; SUBSIDY_MESSAGE_SIZE];
+
+    bytes[..u64::SIZE].copy_from_slice(&counter.to_bytes());
+    bytes[u64::SIZE..].copy_from_slice(&value.to_bytes());
+
+    bytes
+}
+
+impl Charlie {
+    fn gas_price() -> u64 {
+        rusk_abi::call::<(), u64>(TRANSFER_CONTRACT, "gas_price", &())
+            .expect("Obtaining gas price should succeed")
+    }
+
+    /// calling this method will be paid by the contract
+    pub fn pay(&mut self) {
+        const ALLOWANCE: u64 = 40_000_000;
+        let allowance = ALLOWANCE / Self::gas_price();
+        // this call is paid for by the contract, up to 'allowance'
+        rusk_abi::set_allowance(allowance);
+    }
+
+    /// calling this method should be paid by the contract, yet it
+    /// sets the allowance to a value too small to cover
+    /// the execution cost, transaction will fail
+    /// and contract balance won't be affected
+    pub fn pay_and_fail(&mut self) {
+        const ALLOWANCE: u64 = 8_000_000;
+        let allowance = ALLOWANCE / Self::gas_price();
+        // this call is paid for by the contract, up to 'allowance'
+        rusk_abi::set_allowance(allowance);
+    }
+
+    /// calling this method will cause the transaction fee to be
+    /// increased so that contract can earn the difference between
+    /// the contract's charge and the cost of gas actually spent
+    pub fn earn(&mut self) {
+        const CHARGE: u64 = 80_000_000;
+        let charge = CHARGE / Self::gas_price();
+        // charging 'charge' for the call
+        rusk_abi::set_charge(charge);
+    }
+
+    /// calling this method will cause the transaction fee to be
+    /// increased, yet its sets the charge to a value  too small to cover
+    /// the actual execution cost, as a result the transaction will fail
+    /// and contract balance won't be affected
+    pub fn earn_and_fail(&mut self) {
+        const CHARGE: u64 = 8_000_000;
+        let charge = CHARGE / Self::gas_price();
+        // charging 'charge' for the call
+        rusk_abi::set_charge(charge);
+    }
+
+    /// this method calls the `earn` method indirectly, and in such case, since
+    /// charge is set by an indirectly called method, it won't have effect and
+    /// contract balance won't be affected
+    pub fn earn_indirectly_and_fail(&mut self) {
+        rusk_abi::call::<_, ()>(rusk_abi::self_id(), "earn", &())
+            .expect("earn call should succeed");
+    }
+
+    /// Subsidizes the contract with funds which can then be used
+    /// for sponsoring free uses of other methods of this contract.
+    /// Funds passed in this call will be used when granting allowances.
+    /// The subsidy operation is similar to staking, yet the funds
+    /// are deposited in this contract's "wallet".
+    pub fn subsidize(&mut self, subsidy: Subsidy) {
+        // verify the signature is over the correct digest
+        // note: counter is always zero - make sure that this is safe
+        let digest = subsidy_signature_message(0, subsidy.value).to_vec();
+
+        if !rusk_abi::verify_bls(digest, subsidy.public_key, subsidy.signature)
+        {
+            panic!("Invalid signature!");
+        }
+
+        // make call to transfer contract to transfer balance from the user to
+        // this contract
+        let transfer_module = TRANSFER_CONTRACT;
+
+        let stct = Stct {
+            module: rusk_abi::self_id().to_bytes(),
+            value: subsidy.value,
+            proof: subsidy.proof,
+        };
+
+        // subsidizing self with 'subsidy.value'
+        rusk_abi::call::<_, bool>(transfer_module, "stct", &stct)
+            .expect("Sending note to contract should succeed");
+    }
+}

contracts/stake/tests/common/utils.rs

@@ -13,7 +13,10 @@ use execution_core::{
     transfer::{TreeLeaf, TRANSFER_TREE_DEPTH},
     Note, Transaction, ViewKey,
 };
-use rusk_abi::{CallReceipt, ContractError, Error, Session, TRANSFER_CONTRACT};
+use rusk_abi::{
+    CallReceipt, ContractError, ContractId, EconomicMode, Error, Session,
+    TRANSFER_CONTRACT,
+};
 
 const POINT_LIMIT: u64 = 0x100000000;
 
@@ -110,7 +113,12 @@ pub fn execute(
         .call::<_, ()>(
             TRANSFER_CONTRACT,
             "refund",
-            &(tx.fee, receipt.gas_spent),
+            &(
+                tx.fee,
+                receipt.gas_spent,
+                EconomicMode::None,
+                None::<ContractId>,
+            ),
             u64::MAX,
         )
         .expect("Refunding must succeed");

contracts/transfer/CHANGELOG.md

@@ -7,6 +7,11 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased
 
+### Added
+
+- Added support for Economic Protocol scenario 3 [#1630]
+- Added method which exposes the current gas price [#1604]
+
 ### Changed
 
 - Change dependencies declarations enforce bytecheck [#1371]
@@ -17,5 +22,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [0.7.0] - 2023-12-15
 
+[#1630]: https://github.com/dusk-network/rusk/issues/1630
+[#1604]: https://github.com/dusk-network/rusk/issues/1604
 [#1675]: https://github.com/dusk-network/rusk/issues/1675
 [#1371]: https://github.com/dusk-network/rusk/issues/1371

contracts/transfer/Cargo.toml

@@ -24,6 +24,7 @@ rusk-profile = { version = "0.6", path = "../../rusk-profile" }
 rusk-abi = { version = "0.13.0-rc", path = "../../rusk-abi", default-features = false, features = ["host"] }
 transfer-circuits = { version = "0.5", path = "../../circuits/transfer" }
 rkyv = { version = "0.7", default-features = false, features = ["size_32"] }
+bytecheck = { version = "0.6", default-features = false }
 hex = "0.4"
 rand = "0.8"
 ff = { version = "0.13", default-features = false }

contracts/transfer/src/lib.rs

@@ -85,6 +85,11 @@ unsafe fn num_notes(arg_len: u32) -> u32 {
     rusk_abi::wrap_call(arg_len, |_: ()| STATE.num_notes())
 }
 
+#[no_mangle]
+unsafe fn gas_price(arg_len: u32) -> u32 {
+    rusk_abi::wrap_call(arg_len, |_: ()| STATE.gas_price())
+}
+
 // "Feeder" queries
 
 #[no_mangle]
@@ -109,10 +114,13 @@ unsafe fn spend_and_execute(arg_len: u32) -> u32 {
 
 #[no_mangle]
 unsafe fn refund(arg_len: u32) -> u32 {
-    rusk_abi::wrap_call(arg_len, |(fee, gas_spent)| {
-        assert_external_caller();
-        STATE.refund(fee, gas_spent)
-    })
+    rusk_abi::wrap_call(
+        arg_len,
+        |(fee, gas_spent, economic_mode, contract_id)| {
+            assert_external_caller();
+            STATE.refund(fee, gas_spent, economic_mode, contract_id)
+        },
+    )
 }
 
 #[no_mangle]