Fix callbacks of IBC Module

.gas-snapshot

@@ -1,9 +1,9 @@
-IBCTest:testBenchmarkCreateMockClient() (gas: 214252)
-IBCTest:testBenchmarkRecvPacket() (gas: 157441)
-IBCTest:testBenchmarkSendPacket() (gas: 85940)
-IBCTest:testBenchmarkUpdateMockClient() (gas: 129807)
-IBCTest:testConnectionOpenInit() (gas: 496548)
-IBCTest:testSendPacketInvalidTimestamp() (gas: 39167)
+IBCTest:testBenchmarkCreateMockClient() (gas: 214230)
+IBCTest:testBenchmarkRecvPacket() (gas: 157447)
+IBCTest:testBenchmarkSendPacket() (gas: 86050)
+IBCTest:testBenchmarkUpdateMockClient() (gas: 129918)
+IBCTest:testConnectionOpenInit() (gas: 496526)
+IBCTest:testSendPacketInvalidTimestamp() (gas: 39277)
 IBCTest:testToUint128((uint64,uint64)) (runs: 256, μ: 1047, ~: 1047)
 TestICS20:testAddressToHex(address) (runs: 256, μ: 23720, ~: 23889)
 TestICS20:testHexToAddress(string) (runs: 256, μ: 4817, ~: 4829)

contracts/apps/20-transfer/ICS20Transfer.sol

@@ -11,6 +11,8 @@ import "solidity-bytes-utils/contracts/BytesLib.sol";
 abstract contract ICS20Transfer is IBCAppBase {
     using BytesLib for bytes;
 
+    string public constant ICS20_VERSION = "ics20-1";
+
     mapping(string => address) channelEscrowAddresses;
 
     function onRecvPacket(Packet.Data calldata packet, address)
@@ -71,26 +73,45 @@ abstract contract ICS20Transfer is IBCAppBase {
     }
 
     function onChanOpenInit(
-        Channel.Order,
+        Channel.Order order,
         string[] calldata,
         string calldata,
         string calldata channelId,
         ChannelCounterparty.Data calldata,
-        string calldata
-    ) external virtual override onlyIBC {
+        string calldata version
+    ) external virtual override onlyIBC returns (string memory) {
+        require(order == Channel.Order.ORDER_UNORDERED, "must be unordered");
+        bytes memory versionBytes = bytes(version);
+        require(versionBytes.length == 0 || keccak256(versionBytes) == keccak256(bytes(ICS20_VERSION)));
         channelEscrowAddresses[channelId] = address(this);
+        return ICS20_VERSION;
     }
 
     function onChanOpenTry(
-        Channel.Order,
+        Channel.Order order,
         string[] calldata,
         string calldata,
         string calldata channelId,
         ChannelCounterparty.Data calldata,
-        string calldata,
-        string calldata
-    ) external virtual override onlyIBC {
+        string calldata counterpartyVersion
+    ) external virtual override onlyIBC returns (string memory) {
+        require(order == Channel.Order.ORDER_UNORDERED, "must be unordered");
+        require(keccak256(bytes(counterpartyVersion)) == keccak256(bytes(ICS20_VERSION)));
         channelEscrowAddresses[channelId] = address(this);
+        return ICS20_VERSION;
+    }
+
+    function onChanOpenAck(string calldata, string calldata, string calldata counterpartyVersion)
+        external
+        virtual
+        override
+        onlyIBC
+    {
+        require(keccak256(bytes(counterpartyVersion)) == keccak256(bytes(ICS20_VERSION)));
+    }
+
+    function onChanCloseInit(string calldata, string calldata) external virtual override onlyIBC {
+        revert("not allowed");
     }
 
     function onTimeoutPacket(Packet.Data calldata packet, address) external virtual override onlyIBC {

contracts/apps/commons/IBCAppBase.sol

@@ -40,7 +40,7 @@ abstract contract IBCAppBase is Context, IIBCModule {
         string calldata channelId,
         ChannelCounterparty.Data calldata,
         string calldata
-    ) external virtual override onlyIBC {}
+    ) external virtual override onlyIBC returns (string memory) {}
 
     /**
      * @dev See IIBCModule-onChanOpenTry
@@ -53,9 +53,8 @@ abstract contract IBCAppBase is Context, IIBCModule {
         string calldata,
         string calldata channelId,
         ChannelCounterparty.Data calldata,
-        string calldata,
         string calldata
-    ) external virtual override onlyIBC {}
+    ) external virtual override onlyIBC returns (string memory) {}
 
     /**
      * @dev See IIBCModule-onChanOpenAck

contracts/core/05-port/IIBCModule.sol

@@ -23,7 +23,7 @@ interface IIBCModule {
         string calldata channelId,
         ChannelCounterparty.Data calldata counterparty,
         string calldata version
-    ) external;
+    ) external returns (string memory);
 
     // OnChanOpenTry will verify the relayer-chosen parameters along with the
     // counterparty-chosen version string and perform custom TRY logic.
@@ -39,9 +39,8 @@ interface IIBCModule {
         string calldata portId,
         string calldata channelId,
         ChannelCounterparty.Data calldata counterparty,
-        string calldata version,
         string calldata counterpartyVersion
-    ) external;
+    ) external returns (string memory);
 
     // OnChanOpenAck will error if the counterparty selected version string
     // is invalid to abort the handshake. It may also perform custom ACK logic.

contracts/core/25-handler/IBCChannelHandler.sol

@@ -24,13 +24,16 @@ abstract contract IBCChannelHandler is ModuleManager {
         ibcChannel = _ibcChannel;
     }
 
-    function channelOpenInit(IBCMsgs.MsgChannelOpenInit calldata msg_) external returns (string memory channelId) {
+    function channelOpenInit(IBCMsgs.MsgChannelOpenInit calldata msg_)
+        external
+        returns (string memory channelId, string memory version)
+    {
         bytes memory res =
             ibcChannel.functionDelegateCall(abi.encodeWithSelector(IIBCChannelHandshake.channelOpenInit.selector, msg_));
         channelId = abi.decode(res, (string));
 
         IIBCModule module = lookupModuleByPort(msg_.portId);
-        module.onChanOpenInit(
+        version = module.onChanOpenInit(
             msg_.channel.ordering,
             msg_.channel.connection_hops,
             msg_.portId,
@@ -40,30 +43,28 @@ abstract contract IBCChannelHandler is ModuleManager {
         );
         claimCapability(channelCapabilityPath(msg_.portId, channelId), address(module));
         emit GeneratedChannelIdentifier(channelId);
-        return channelId;
+        return (channelId, version);
     }
 
-    function channelOpenTry(IBCMsgs.MsgChannelOpenTry calldata msg_) external returns (string memory channelId) {
-        {
-            // avoid "Stack too deep" error
-            bytes memory res = ibcChannel.functionDelegateCall(
-                abi.encodeWithSelector(IIBCChannelHandshake.channelOpenTry.selector, msg_)
-            );
-            channelId = abi.decode(res, (string));
-        }
+    function channelOpenTry(IBCMsgs.MsgChannelOpenTry calldata msg_)
+        external
+        returns (string memory channelId, string memory version)
+    {
+        bytes memory res =
+            ibcChannel.functionDelegateCall(abi.encodeWithSelector(IIBCChannelHandshake.channelOpenTry.selector, msg_));
+        channelId = abi.decode(res, (string));
         IIBCModule module = lookupModuleByPort(msg_.portId);
-        module.onChanOpenTry(
+        version = module.onChanOpenTry(
             msg_.channel.ordering,
             msg_.channel.connection_hops,
             msg_.portId,
             channelId,
             msg_.channel.counterparty,
-            msg_.channel.version,
             msg_.counterpartyVersion
         );
         claimCapability(channelCapabilityPath(msg_.portId, channelId), address(module));
         emit GeneratedChannelIdentifier(channelId);
-        return channelId;
+        return (channelId, version);
     }
 
     function channelOpenAck(IBCMsgs.MsgChannelOpenAck calldata msg_) external {