introduce support for PostResponse timeouts (#13)

* introduce support for PostResponse timeouts

* clean up interfaces

src/IConsensusClient.sol

@@ -1,8 +1,6 @@
 // SPDX-License-Identifier: UNLICENSED
 pragma solidity 0.8.17;
 
-import "solidity-merkle-trees/MerklePatricia.sol";
-
 // The state commiment identifies a commiment to some intermediate state in the state machine.
 // This contains some metadata about the state machine like it's own timestamp at the time of this commitment.
 struct StateCommitment {

src/IHandler.sol

@@ -1,8 +1,15 @@
 // SPDX-License-Identifier: UNLICENSED
 pragma solidity 0.8.17;
 
-import "./IIsmpHost.sol";
-import "./IIsmp.sol";
+import {IIsmpHost} from "./IIsmpHost.sol";
+import {
+    PostRequestMessage,
+    PostResponseMessage,
+    GetResponseMessage,
+    PostRequestTimeoutMessage,
+    PostResponseTimeoutMessage,
+    GetTimeoutMessage
+} from "./IIsmp.sol";
 
 /*
     The IHandler interface serves as the entry point for ISMP datagrams, i.e consensus, requests & response messages.
@@ -43,12 +50,19 @@ interface IHandler {
      * @param host - Ismp host
      * @param message - batch post request timeouts
      */
-    function handlePostTimeouts(IIsmpHost host, PostTimeoutMessage memory message) external;
+    function handlePostRequestTimeouts(IIsmpHost host, PostRequestTimeoutMessage memory message) external;
+
+    /**
+     * @dev check timeout proofs then dispatch to modules
+     * @param host - Ismp host
+     * @param message - batch post response timeouts
+     */
+    function handlePostResponseTimeouts(IIsmpHost host, PostResponseTimeoutMessage memory message) external;
 
     /**
      * @dev dispatch to modules
      * @param host - Ismp host
      * @param message - batch get request timeouts
      */
-    function handleGetTimeouts(IIsmpHost host, GetTimeoutMessage memory message) external;
+    function handleGetRequestTimeouts(IIsmpHost host, GetTimeoutMessage memory message) external;
 }

src/IIsmp.sol

@@ -1,8 +1,7 @@
 // SPDX-License-Identifier: UNLICENSED
 pragma solidity 0.8.17;
 
-import "solidity-merkle-trees/MerklePatricia.sol";
-
+import {StorageValue} from "solidity-merkle-trees/MerklePatricia.sol";
 import {StateMachineHeight} from "./IConsensusClient.sol";
 
 struct PostRequest {
@@ -39,7 +38,7 @@ struct GetRequest {
     bytes[] keys;
     // height at which to read destination state machine
     uint64 height;
-    // gas limit for executing this request on destination & its response (if any) on the source.
+    // gas limit for executing this request on destination
     uint64 gaslimit;
 }
 
@@ -55,6 +54,10 @@ struct PostResponse {
     PostRequest request;
     // bytes for post response
     bytes response;
+    // timestamp by which this response times out.
+    uint64 timeoutTimestamp;
+    // gas limit for executing this response on destination which is the source of the request.
+    uint64 gaslimit;
 }
 
 // A post request as a leaf in a merkle tree
@@ -114,7 +117,7 @@ struct PostTimeout {
     PostRequest request;
 }
 
-struct PostTimeoutMessage {
+struct PostRequestTimeoutMessage {
     // requests which have timed-out
     PostRequest[] timeouts;
     // the height of the state machine proof
@@ -123,6 +126,15 @@ struct PostTimeoutMessage {
     bytes[] proof;
 }
 
+struct PostResponseTimeoutMessage {
+    // responses which have timed-out
+    PostResponse[] timeouts;
+    // the height of the state machine proof
+    StateMachineHeight height;
+    // non-membership proof of the requests
+    bytes[] proof;
+}
+
 // A message for handling incoming responses
 struct PostResponseMessage {
     // proof for the responses
@@ -143,6 +155,8 @@ struct DispatchPost {
     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 amount;
 }
 
 // An object for dispatching get requests to the IsmpDispatcher
@@ -157,6 +171,21 @@ struct DispatchGet {
     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 amount;
+}
+
+struct DispatchPostResponse {
+    // The request that initiated this response
+    PostRequest request;
+    // bytes for post response
+    bytes response;
+    // timestamp by which this response times out.
+    uint64 timeoutTimestamp;
+    // 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 amount;
 }
 
 // The core ISMP API, IIsmpModules use this interface to send outgoing get/post requests & responses
@@ -167,38 +196,17 @@ interface IIsmp {
      */
     function dispatch(DispatchPost memory request) external;
 
-    /**
-     * @dev Dispatch a POST request to the ISMP router and pay for a relayer.
-     * The amount provided is charged to tx.origin in $DAI.
-     * @param request - post request
-     */
-    function dispatch(DispatchPost memory request, uint256 amount) external;
-
     /**
      * @dev Dispatch a GET request to the ISMP router.
      * @param request - get request
      */
     function dispatch(DispatchGet memory request) external;
 
-    /**
-     * @dev Dispatch a GET request to the ISMP router and pay for a relayer.
-     * The amount provided is charged to tx.origin in $DAI.
-     * @param request - get request
-     */
-    function dispatch(DispatchGet memory request, uint256 amount) external;
-
     /**
      * @dev Provide a response to a previously received request.
      * @param response - post response
      */
     function dispatch(PostResponse memory response) external;
-
-    /**
-     * @dev Provide a response to a previously received request.
-     * The amount provided is charged to tx.origin in $DAI.
-     * @param response - post response
-     */
-    function dispatch(PostResponse memory response, uint256 amount) external;
 }
 
 library Message {
@@ -209,10 +217,13 @@ library Message {
                 res.request.dest,
                 res.request.nonce,
                 res.request.timeoutTimestamp,
-                res.request.body,
                 res.request.from,
                 res.request.to,
-                res.response
+                res.request.body,
+                res.request.gaslimit,
+                res.response,
+                res.timeoutTimestamp,
+                res.gaslimit
             )
         );
     }
@@ -240,23 +251,6 @@ library Message {
     }
 
     function hash(GetResponse memory res) internal pure returns (bytes32) {
-        bytes memory keysEncoding = abi.encode(res.request.keys);
-        bytes memory preimage = abi.encodePacked(
-            res.request.source,
-            res.request.dest,
-            res.request.nonce,
-            res.request.height,
-            res.request.timeoutTimestamp,
-            res.request.from,
-            keysEncoding,
-            res.request.gaslimit
-        );
-        uint256 len = res.values.length;
-        for (uint256 i = 0; i < len; i++) {
-            StorageValue memory entry = res.values[i];
-            preimage = bytes.concat(preimage, abi.encodePacked(entry.key, entry.value));
-        }
-
-        return keccak256(preimage);
+        return hash(res.request);
     }
 }

src/IIsmpHost.sol

@@ -158,13 +158,19 @@ interface IIsmpHost is IIsmp {
 
     /**
      * @dev Dispatch an incoming get timeout to source module
-     * @param timeout - get timeout
+     * @param timeout - timed-out get request
      */
     function dispatchIncoming(GetRequest memory timeout, RequestMetadata memory meta, bytes32 commitment) external;
 
     /**
      * @dev Dispatch an incoming post timeout to source module
-     * @param timeout - post timeout
+     * @param timeout - timed-out post request
      */
-    function dispatchIncoming(PostTimeout memory timeout, RequestMetadata memory meta, bytes32 commitment) external;
+    function dispatchIncoming(PostRequest memory timeout, RequestMetadata memory meta, bytes32 commitment) external;
+
+    /**
+     * @dev Dispatch an incoming post response timeout to source module
+     * @param timeout - timed-out post response
+     */
+    function dispatchIncoming(PostResponse memory timeout, RequestMetadata memory meta, bytes32 commitment) external;
 }

src/IIsmpModule.sol

@@ -1,35 +1,41 @@
 // SPDX-License-Identifier: UNLICENSED
 pragma solidity 0.8.17;
 
-import "./IIsmp.sol";
+import {PostRequest, PostResponse, GetResponse, GetRequest} from "./IIsmp.sol";
 
 interface IIsmpModule {
     /**
-     * @dev Called by the local ISMP router on a module, to notify module of a new request the module may choose to respond immediately, or in a later block
+     * @dev Called by the IsmpHost to notify a module of a new request the module may choose to respond immediately, or in a later block
      * @param request post request
      */
     function onAccept(PostRequest memory request) external;
 
     /**
-     * @dev Called by the router on a module, to notify module of a post response to a previously sent out request
+     * @dev Called by the IsmpHost to notify a module of a post response to a previously sent out request
      * @param response post response
      */
     function onPostResponse(PostResponse memory response) external;
 
     /**
-     * @dev Called by the router on a module, to notify module of a get response to a previously sent out request
+     * @dev Called by the IsmpHost to notify a module of a get response to a previously sent out request
      * @param response get response
      */
     function onGetResponse(GetResponse memory response) external;
 
     /**
-     * @dev Called by the router on a module, to notify module of post requests that were previously sent but have now timed-out
+     * @dev Called by the IsmpHost to notify a module of post requests that were previously sent but have now timed-out
      * @param request post request
      */
-    function onPostTimeout(PostRequest memory request) external;
+    function onPostRequestTimeout(PostRequest memory request) external;
 
     /**
-     * @dev Called by the router on a module, to notify module of get requests that were previously sent but have now timed-out
+     * @dev Called by the IsmpHost to notify a module of post requests that were previously sent but have now timed-out
+     * @param request post request
+     */
+    function onPostResponseTimeout(PostResponse memory request) external;
+
+    /**
+     * @dev Called by the IsmpHost to notify a module of get requests that were previously sent but have now timed-out
      * @param request get request
      */
     function onGetTimeout(GetRequest memory request) external;

src/StateMachine.sol

@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: UNLICENSED
 pragma solidity 0.8.17;
 
-import "openzeppelin/utils/Strings.sol";
+import {Strings} from "openzeppelin/utils/Strings.sol";
 
 library StateMachine {
     /// The identifier for the relay chain.