API refactor (#16)

* some api changes

* add missing files

src/IDispatcher.sol

@@ -0,0 +1,71 @@
+// SPDX-License-Identifier: UNLICENSED
+pragma solidity 0.8.17;
+
+import {StateMachineHeight} from "./IConsensusClient.sol";
+import {PostRequest} from "./Message.sol";
+
+// An object for dispatching post requests to the IsmpDispatcher
+struct DispatchPost {
+    // bytes representation of the destination state machine
+    bytes dest;
+    // the destination module
+    bytes to;
+    // the request body
+    bytes body;
+    // timeout for this request in seconds
+    uint64 timeout;
+    // gas limit for executing this request on destination & its response (if any) on the source.
+    uint64 gaslimit;
+    // the amount put up to be paid to the relayer, this is in $DAI and charged to tx.origin
+    uint256 fee;
+}
+
+// An object for dispatching get requests to the IsmpDispatcher
+struct DispatchGet {
+    // bytes representation of the destination state machine
+    bytes dest;
+    // height at which to read the state machine
+    uint64 height;
+    // Storage keys to read
+    bytes[] keys;
+    // timeout for this request in seconds
+    uint64 timeout;
+    // gas limit for executing this request on destination & its response (if any) on the source.
+    uint64 gaslimit;
+    // the amount put up to be paid to the relayer, this is in $DAI and charged to tx.origin
+    uint256 fee;
+}
+
+struct DispatchPostResponse {
+    // The request that initiated this response
+    PostRequest request;
+    // bytes for post response
+    bytes response;
+    // timeout for this response in seconds
+    uint64 timeout;
+    // gas limit for executing this response on destination which is the source of the request.
+    uint64 gaslimit;
+    // the amount put up to be paid to the relayer, this is in $DAI and charged to tx.origin
+    uint256 fee;
+}
+
+// The core ISMP API, IIsmpModules use this interface to send outgoing get/post requests & responses
+interface IDispatcher {
+    /**
+     * @dev Dispatch a post request to the ISMP router.
+     * @param request - post request
+     */
+    function dispatch(DispatchPost memory request) external;
+
+    /**
+     * @dev Dispatch a GET request to the ISMP router.
+     * @param request - get request
+     */
+    function dispatch(DispatchGet memory request) external;
+
+    /**
+     * @dev Provide a response to a previously received request.
+     * @param response - post response
+     */
+    function dispatch(DispatchPostResponse memory response) external;
+}

src/IHandler.sol

@@ -9,7 +9,7 @@ import {
     PostRequestTimeoutMessage,
     PostResponseTimeoutMessage,
     GetTimeoutMessage
-} from "./IIsmp.sol";
+} from "./Message.sol";
 
 /*
     The IHandler interface serves as the entry point for ISMP datagrams, i.e consensus, requests & response messages.

src/IIsmpHost.sol

@@ -2,7 +2,8 @@
 pragma solidity 0.8.17;
 
 import {StateCommitment, StateMachineHeight} from "./IConsensusClient.sol";
-import {IIsmp, PostRequest, PostResponse, GetResponse, PostTimeout, GetRequest} from "./IIsmp.sol";
+import {IDispatcher} from "./IDispatcher.sol";
+import {PostRequest, PostResponse, GetResponse, PostTimeout, GetRequest} from "./Message.sol";
 
 // Some metadata about the request
 struct FeeMetadata {
@@ -19,7 +20,7 @@ struct ResponseReceipt {
     address relayer;
 }
 
-interface IIsmpHost is IIsmp {
+interface IIsmpHost is IDispatcher {
     /**
      * @return the host admin
      */
@@ -28,22 +29,27 @@ interface IIsmpHost is IIsmp {
     /**
      * @return the address of the DAI ERC-20 contract on this state machine
      */
-    function dai() external returns (address);
+    function dai() external view returns (address);
+
+    /**
+     * @return the per-byte fee for outgoing requests.
+     */
+    function perByteFee() external view returns (uint256);
 
     /**
      * @return the host state machine id
      */
-    function host() external returns (bytes memory);
+    function host() external view returns (bytes memory);
 
     /**
      * @return the host timestamp
      */
-    function timestamp() external returns (uint256);
+    function timestamp() external view returns (uint256);
 
     /**
      * @return the `frozen` status
      */
-    function frozen() external returns (bool);
+    function frozen() external view returns (bool);
 
     /**
      * @param height - state machine height
@@ -61,56 +67,56 @@ interface IIsmpHost is IIsmp {
      * @dev Should return a handle to the consensus client based on the id
      * @return the consensus client contract
      */
-    function consensusClient() external returns (address);
+    function consensusClient() external view returns (address);
 
     /**
      * @return the last updated time of the consensus client
      */
-    function consensusUpdateTime() external returns (uint256);
+    function consensusUpdateTime() external view returns (uint256);
 
     /**
      * @return the latest state machine height
      */
-    function latestStateMachineHeight() external returns (uint256);
+    function latestStateMachineHeight() external view returns (uint256);
 
     /**
      * @return the state of the consensus client
      */
-    function consensusState() external returns (bytes memory);
+    function consensusState() external view returns (bytes memory);
 
     /**
      * @param commitment - commitment to the request
      * @return relayer address
      */
-    function requestReceipts(bytes32 commitment) external returns (address);
+    function requestReceipts(bytes32 commitment) external view returns (address);
 
     /**
      * @param commitment - commitment to the request of the response
      * @return response receipt
      */
-    function responseReceipts(bytes32 commitment) external returns (ResponseReceipt memory);
+    function responseReceipts(bytes32 commitment) external view returns (ResponseReceipt memory);
 
     /**
      * @param commitment - commitment to the request
      * @return existence status of an outgoing request commitment
      */
-    function requestCommitments(bytes32 commitment) external returns (FeeMetadata memory);
+    function requestCommitments(bytes32 commitment) external view returns (FeeMetadata memory);
 
     /**
      * @param commitment - commitment to the response
      * @return existence status of an outgoing response commitment
      */
-    function responseCommitments(bytes32 commitment) external returns (FeeMetadata memory);
+    function responseCommitments(bytes32 commitment) external view returns (FeeMetadata memory);
 
     /**
      * @return the challenge period
      */
-    function challengePeriod() external returns (uint256);
+    function challengePeriod() external view returns (uint256);
 
     /**
      * @return the unstaking period
      */
-    function unStakingPeriod() external returns (uint256);
+    function unStakingPeriod() external view returns (uint256);
 
     /**
      * @dev Store an encoded consensus state

src/IIsmpModule.sol

@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: UNLICENSED
 pragma solidity 0.8.17;
 
-import {PostRequest, PostResponse, GetResponse, GetRequest} from "./IIsmp.sol";
+import {PostRequest, PostResponse, GetResponse, GetRequest} from "./Message.sol";
 
 interface IIsmpModule {
     /**
@@ -40,3 +40,30 @@ interface IIsmpModule {
      */
     function onGetTimeout(GetRequest memory request) external;
 }
+
+/// Abstract contract to make implementing `IIsmpModule` easier.
+abstract contract BaseIsmpModule is IIsmpModule {
+    function onAccept(PostRequest calldata) external virtual {
+        revert("IsmpModule doesn't expect Post requests");
+    }
+
+    function onPostRequestTimeout(PostRequest memory) external virtual {
+        revert("IsmpModule doesn't emit Post requests");
+    }
+
+    function onPostResponse(PostResponse memory) external virtual {
+        revert("IsmpModule doesn't emit Post responses");
+    }
+
+    function onPostResponseTimeout(PostResponse memory) external virtual {
+        revert("IsmpModule doesn't emit Post responses");
+    }
+
+    function onGetResponse(GetResponse memory) external virtual {
+        revert("IsmpModule doesn't emit Get requests");
+    }
+
+    function onGetTimeout(GetRequest memory) external virtual {
+        revert("IsmpModule doesn't emit Get requests");
+    }
+}

src/IIsmp.sol → src/Message.sol

@@ -1,8 +1,8 @@
 // SPDX-License-Identifier: UNLICENSED
 pragma solidity 0.8.17;
 
-import {StorageValue} from "solidity-merkle-trees/MerklePatricia.sol";
 import {StateMachineHeight} from "./IConsensusClient.sol";
+import {StorageValue} from "solidity-merkle-trees/MerklePatricia.sol";
 
 struct PostRequest {
     // the source state machine of this request
@@ -143,72 +143,6 @@ struct PostResponseMessage {
     PostResponseLeaf[] responses;
 }
 
-// An object for dispatching post requests to the IsmpDispatcher
-struct DispatchPost {
-    // bytes representation of the destination state machine
-    bytes dest;
-    // the destination module
-    bytes to;
-    // the request body
-    bytes body;
-    // timeout for this request in seconds
-    uint64 timeout;
-    // gas limit for executing this request on destination & its response (if any) on the source.
-    uint64 gaslimit;
-    // the amount put up to be paid to the relayer, this is in $DAI and charged to tx.origin
-    uint256 fee;
-}
-
-// An object for dispatching get requests to the IsmpDispatcher
-struct DispatchGet {
-    // bytes representation of the destination state machine
-    bytes dest;
-    // height at which to read the state machine
-    uint64 height;
-    // Storage keys to read
-    bytes[] keys;
-    // timeout for this request in seconds
-    uint64 timeout;
-    // gas limit for executing this request on destination & its response (if any) on the source.
-    uint64 gaslimit;
-    // the amount put up to be paid to the relayer, this is in $DAI and charged to tx.origin
-    uint256 fee;
-}
-
-struct DispatchPostResponse {
-    // The request that initiated this response
-    PostRequest request;
-    // bytes for post response
-    bytes response;
-    // timeout for this response in seconds
-    uint64 timeout;
-    // gas limit for executing this response on destination which is the source of the request.
-    uint64 gaslimit;
-    // the amount put up to be paid to the relayer, this is in $DAI and charged to tx.origin
-    uint256 fee;
-}
-
-// The core ISMP API, IIsmpModules use this interface to send outgoing get/post requests & responses
-interface IIsmp {
-    /**
-     * @dev Dispatch a post request to the ISMP router.
-     * @param request - post request
-     */
-    function dispatch(DispatchPost memory request) external;
-
-    /**
-     * @dev Dispatch a GET request to the ISMP router.
-     * @param request - get request
-     */
-    function dispatch(DispatchGet memory request) external;
-
-    /**
-     * @dev Provide a response to a previously received request.
-     * @param response - post response
-     */
-    function dispatch(DispatchPostResponse memory response) external;
-}
-
 library Message {
     function timeout(PostRequest memory req) internal pure returns (uint64) {
         if (req.timeoutTimestamp == 0) {

src/StateMachine.sol

@@ -8,42 +8,42 @@ library StateMachine {
     uint256 public constant RELAY_CHAIN = 0;
 
     // Address a state machine on the polkadot relay chain
-    function polkadot(uint256 id) public pure returns (bytes memory) {
+    function polkadot(uint256 id) internal pure returns (bytes memory) {
         return bytes(string.concat("POLKADOT-", Strings.toString(id)));
     }
 
     // Address a state machine on the kusama relay chain
-    function kusama(uint256 id) public pure returns (bytes memory) {
+    function kusama(uint256 id) internal pure returns (bytes memory) {
         return bytes(string.concat("KUSAMA-", Strings.toString(id)));
     }
 
     // Address the ethereum "execution layer"
-    function ethereum() public pure returns (bytes memory) {
+    function ethereum() internal pure returns (bytes memory) {
         return bytes("ETHE");
     }
 
     // Address the Arbitrum state machine
-    function arbitrum() public pure returns (bytes memory) {
+    function arbitrum() internal pure returns (bytes memory) {
         return bytes("ARBI");
     }
 
     // Address the Optimism state machine
-    function optimism() public pure returns (bytes memory) {
+    function optimism() internal pure returns (bytes memory) {
         return bytes("OPTI");
     }
 
     // Address the Base state machine
-    function base() public pure returns (bytes memory) {
+    function base() internal pure returns (bytes memory) {
         return bytes("BASE");
     }
 
     // Address the Polygon POS state machine
-    function polygon() public pure returns (bytes memory) {
+    function polygon() internal pure returns (bytes memory) {
         return bytes("POLY");
     }
 
     // Address the Binance smart chain state machine
-    function bsc() public pure returns (bytes memory) {
+    function bsc() internal pure returns (bytes memory) {
         return bytes("BSC");
     }
 }