feat: add withdraw function to Gateway

contracts/Gateway.sol

@@ -303,6 +303,20 @@ contract Gateway is IGateway, GatewaySettingManager, PausableUpgradeable {
         emit OrderSettledIn(_provider, _sender, _amount, _token, _orderId);
     }
 
+	/** @dev See {withdrawFrom-IGateway} */
+	function withdrawFrom(address provider, address recipient, uint256 _amount, address _token, bytes memory _signature) external isValidAmount(_amount) onlyAggregator returns (bool) {
+		bytes32 messageHash = keccak256(abi.encodePacked(provider, recipient, _amount, _token));
+		bytes32 ethSignedMessageHash = messageHash.toEthSignedMessageHash();
+		address signer = ethSignedMessageHash.recover(_signature);
+		require(signer == provider, 'InvalidSignature');
+
+		require(balance[_token][provider] >= _amount, 'InsufficientBalance');
+		balance[_token][provider] -= _amount;
+		IERC20(_token).transfer(recipient, _amount);
+		emit Withdrawn(provider, recipient, _amount, _token);
+		return true;
+	}
+
 	/* ##################################################################
                                 VIEW CALLS
     ################################################################## */

contracts/interfaces/IGateway.sol

@@ -75,6 +75,16 @@ interface IGateway {
 	 * @param orderId The ID of the order.
 	 */
 	event OrderSettledIn(address indexed provider, address indexed senderAddress, uint256 indexed amount, address token, bytes32 orderId);
+
+	/**
+	 * @notice Emitted when a withdrawal is made by a provider.
+	 * @param provider The address of the provider.
+	 * @param sender The address of the sender.
+	 * @param amount The amount of the withdrawal.
+	 * @param token The address of the withdrawn token.
+	 */
+	event Withdrawn(address indexed provider, address indexed sender, uint256 amount, address indexed token);
+
 	/* ##################################################################
                                 STRUCTS
     ################################################################## */
@@ -205,6 +215,19 @@ interface IGateway {
         uint256 _amount
     ) external;
 
+	/**
+	 * @notice Withdraws an asset from Gateway.
+	 * @dev Requirements:
+	 * - The provider must have enough balance.
+	 * @param _provider The address of the provider.
+	 * @param _recipient The address of the recipient.
+	 * @param _amount The amount to be withdrawn.
+	 * @param _token The address of the asset.
+	 * @param _signature The signature of the provider.
+	 * @return bool The withdrawal is successful.
+	 */
+	function withdrawFrom(address _provider, address _recipient, uint256 _amount, address _token, bytes memory _signature) external returns (bool);
+
 	/**
 	 * @notice Checks if a token is supported by Gateway.
 	 * @param _token The address of the token to check.

test/gateway/gateway.settleOrderOut.test.js

@@ -154,7 +154,7 @@ describe("Gateway offramp order", function () {
 		)
 			.to.emit(gateway, Events.Gateway.OrderCreated)
 			.withArgs(
-				this.sender.address,
+				this.alice.address,
 				mockUSDT.address,
 				this.orderAmount,
 				this.protocolFee,
@@ -264,7 +264,7 @@ describe("Gateway offramp order", function () {
 		)
 			.to.emit(gateway, Events.Gateway.OrderCreated)
 			.withArgs(
-				this.sender.address,
+				this.alice.address,
 				mockUSDT.address,
 				this.orderAmount,
 				this.protocolFee,

test/gateway/gateway.withdraw.test.js

@@ -0,0 +1,198 @@
+const { ethers } = require("hardhat");
+const { BigNumber } = require("@ethersproject/bignumber");
+
+const { gatewayFixture } = require("../fixtures/gateway.js");
+
+const {
+    deployContract,
+    ZERO_AMOUNT,
+    Errors,
+    Events,
+    mockMintDeposit,
+    assertBalance,
+    assertDepositBalance,
+} = require("../utils/utils.manager.js");
+const { expect } = require("chai");
+
+describe("Gateway Provider withdraw", function () {
+    beforeEach(async function () {
+        [
+            this.deployer,
+            this.treasuryAddress,
+            this.aggregator,
+            this.alice,
+            this.bob,
+            this.Eve,
+            this.hacker,
+            ...this.accounts
+        ] = await ethers.getSigners();
+
+        ({ gateway, mockUSDT } = await gatewayFixture());
+
+        this.mockDAI = await deployContract("MockUSDT");
+
+        this.mockUSDT = mockUSDT;
+        this.gateway = gateway;
+
+        this.depositAmount = ethers.utils.parseEther("1000000");
+
+        await mockMintDeposit(gateway, this.alice, mockUSDT, this.depositAmount);
+        await mockMintDeposit(gateway, this.bob, mockUSDT, this.depositAmount);
+        await mockMintDeposit(gateway, this.Eve, mockUSDT, this.depositAmount);
+        await mockMintDeposit(
+            gateway,
+            this.alice,
+            this.mockDAI,
+            this.depositAmount
+        );
+        await mockMintDeposit(gateway, this.bob, this.mockDAI, this.depositAmount);
+        await mockMintDeposit(gateway, this.Eve, this.mockDAI, this.depositAmount);
+
+        await assertBalance(
+            this.mockUSDT,
+            this.mockDAI,
+            this.alice.address,
+            this.depositAmount
+        );
+        await assertBalance(
+            this.mockUSDT,
+            this.mockDAI,
+            this.bob.address,
+            this.depositAmount
+        );
+        await assertBalance(
+            this.mockUSDT,
+            this.mockDAI,
+            this.Eve.address,
+            this.depositAmount
+        );
+
+        const token = ethers.utils.formatBytes32String("token");
+
+        await expect(
+            this.gateway
+                .connect(this.deployer)
+                .settingManagerBool(token, this.mockUSDT.address, BigNumber.from(1))
+        )
+            .to.emit(this.gateway, Events.Gateway.SettingManagerBool)
+            .withArgs(token, this.mockUSDT.address, BigNumber.from(1));
+
+        const aggregator = ethers.utils.formatBytes32String("aggregator");
+
+		await expect(
+			gateway
+				.connect(this.deployer)
+				.updateProtocolAddress(aggregator, this.aggregator.address)
+		).to.emit(gateway, Events.Gateway.ProtocolAddressUpdated);
+    });
+
+    it("Should withdraw successfully with valid signature", async function () {
+        const amount = ethers.utils.parseEther("1000");
+        const messageHash = ethers.utils.solidityKeccak256(
+            ["address", "address", "uint256", "address",],
+            [this.alice.address, this.bob.address, amount, this.mockUSDT.address]
+        );
+        const signature = await this.alice.signMessage(ethers.utils.arrayify(messageHash));
+
+        await assertDepositBalance(
+            this.gateway,
+            this.mockUSDT.address,
+            this.alice.address,
+            ZERO_AMOUNT
+        );
+
+        await expect(
+            this.gateway
+                .connect(this.alice)
+                .deposit(this.mockUSDT.address, this.depositAmount)
+        )
+            .to.emit(this.gateway, Events.Gateway.Deposit)
+            .withArgs(
+                this.alice.address,
+                this.mockUSDT.address,
+                BigNumber.from(this.depositAmount)
+            );
+
+        await assertDepositBalance(
+            this.gateway,
+            this.mockUSDT.address,
+            this.alice.address,
+            this.depositAmount
+        );
+
+        await expect(
+            this.gateway
+                .connect(this.aggregator)
+                .withdrawFrom(this.alice.address, this.bob.address, amount, this.mockUSDT.address, signature)
+        )
+            .to.emit(this.gateway, Events.Gateway.Withdrawn)
+            .withArgs(this.alice.address, this.bob.address, amount, this.mockUSDT.address);
+
+        await assertDepositBalance(
+            this.gateway,
+            this.mockUSDT.address,
+            this.alice.address,
+            this.depositAmount.sub(amount)
+        );
+
+    });
+
+    it("Should fail with invalid signature", async function () {
+        const amount = ethers.utils.parseEther("1000");
+        const messageHash = ethers.utils.solidityKeccak256(
+            ["address", "address", "uint256", "address"],
+            [this.alice.address, this.bob.address, this.mockUSDT.address, amount]
+        );
+        const ethSignedMessageHash = ethers.utils.hashMessage(messageHash);
+        const invalidSignature = await this.bob.signMessage(ethers.utils.arrayify(ethSignedMessageHash));
+
+        await expect(
+            this.gateway
+                .connect(this.alice)
+                .deposit(this.mockUSDT.address, this.depositAmount)
+        )
+            .to.emit(this.gateway, Events.Gateway.Deposit)
+            .withArgs(
+                this.alice.address,
+                this.mockUSDT.address,
+                BigNumber.from(this.depositAmount)
+            );
+
+        await expect(
+            this.gateway
+                .connect(this.aggregator)
+                .withdrawFrom( this.alice.address, this.bob.address, amount, this.mockUSDT.address, invalidSignature)
+        ).to.be.revertedWith("InvalidSignature");
+    });
+
+    it("Should fail with insufficient balance", async function () {
+        const amount = ethers.utils.parseEther("1000");
+        const messageHash = ethers.utils.solidityKeccak256(
+            ["address", "address", "uint256", "address"],
+            [this.alice.address, this.bob.address, amount, this.mockUSDT.address]
+        );
+        const signature = await this.alice.signMessage(ethers.utils.arrayify(messageHash));
+
+        await expect(
+            this.gateway
+                .connect(this.aggregator)
+                .withdrawFrom(this.alice.address, this.bob.address, amount, this.mockUSDT.address, signature)
+        ).to.be.revertedWith("InsufficientBalance");
+    });
+
+    it("Should fail when called by non-aggregator", async function () {
+        const amount = ethers.utils.parseEther("1000");
+        const messageHash = ethers.utils.solidityKeccak256(
+            ["address", "address", "address", "uint256"],
+            [this.alice.address, this.bob.address, this.mockUSDT.address, amount]
+        );
+        const ethSignedMessageHash = ethers.utils.hashMessage(messageHash);
+        const signature = await this.alice.signMessage(ethers.utils.arrayify(ethSignedMessageHash));
+
+        await expect(
+            this.gateway
+                .connect(this.alice)
+                .withdrawFrom(this.alice.address, this.bob.address, amount, this.mockUSDT.address, signature)
+        ).to.be.revertedWith("OnlyAggregator");
+    });
+});

test/utils/utils.manager.js

@@ -36,6 +36,7 @@ const Events = {
 		ProtocolAddressUpdated: "ProtocolAddressUpdated",
 		Deposit: "Deposit",
 		OrderSettledIn: "OrderSettledIn",
+		Withdrawn: "Withdrawn",
 	},
 };