add hostTimestamp to IBCHost

* fix upgrade timeout unit to nanosecond
* fix overflow check for host timestamp

Signed-off-by: Jun Kimura <jun.kimura@datachain.jp>

Author: bluele

contracts/core/04-channel/IBCChannelPacketSendRecv.sol

@@ -133,8 +133,8 @@ contract IBCChannelPacketSendRecv is
         {
             revert IBCChannelTimeoutPacketHeight(block.number, msg_.packet.timeoutHeight.revision_height);
         }
-        if (msg_.packet.timeoutTimestamp != 0 && block.timestamp * 1e9 >= msg_.packet.timeoutTimestamp) {
-            revert IBCChannelTimeoutPacketTimestamp(block.timestamp * 1e9, msg_.packet.timeoutTimestamp);
+        if (msg_.packet.timeoutTimestamp != 0 && hostTimestamp() >= msg_.packet.timeoutTimestamp) {
+            revert IBCChannelTimeoutPacketTimestamp(hostTimestamp(), msg_.packet.timeoutTimestamp);
         }
 
         verifyPacketCommitment(

contracts/core/04-channel/IBCChannelUpgrade.sol

@@ -549,7 +549,7 @@ contract IBCChannelUpgradeInitTryAck is IBCChannelUpgradeBase, IIBCChannelUpgrad
         Timeout.Data calldata timeout = msg_.counterpartyUpgrade.timeout;
         if (
             (timeout.height.revision_height != 0 && block.number >= timeout.height.revision_height)
-                || (timeout.timestamp != 0 && block.timestamp >= timeout.timestamp)
+                || (timeout.timestamp != 0 && hostTimestamp() >= timeout.timestamp)
         ) {
             restoreChannel(msg_.portId, msg_.channelId, UpgradeHandshakeError.Timeout);
             return false;
@@ -620,7 +620,7 @@ contract IBCChannelUpgradeConfirmTimeoutCancel is IBCChannelUpgradeBase, IIBCCha
         Timeout.Data calldata timeout = msg_.counterpartyUpgrade.timeout;
         if (
             (timeout.height.revision_height != 0 && block.number >= timeout.height.revision_height)
-                || (timeout.timestamp != 0 && block.timestamp >= timeout.timestamp)
+                || (timeout.timestamp != 0 && hostTimestamp() >= timeout.timestamp)
         ) {
             restoreChannel(msg_.portId, msg_.channelId, UpgradeHandshakeError.Timeout);
             return false;

contracts/core/24-host/IBCHost.sol

@@ -10,6 +10,13 @@ contract IBCHost is IIBCHostErrors, IBCStore {
     // In ibc-solidity, the prefix is not required, but for compatibility with ibc-go this must be a non-empty value.
     bytes internal constant DEFAULT_COMMITMENT_PREFIX = bytes("ibc");
 
+    /**
+     * @dev hostTimestamp returns the current timestamp(Unix time in nanoseconds) of the host chain.
+     */
+    function hostTimestamp() internal view virtual returns (uint64) {
+        return uint64(block.timestamp) * 1e9;
+    }
+
     /**
      * @dev _getCommitmentPrefix returns the prefix of the commitment proof.
      */