attempted bug fix of CCIPClient fee-token allowance when pre-funding

contracts/gas-snapshots/ccip.gas-snapshot

@@ -35,9 +35,9 @@ BurnWithFromMintTokenPool_lockOrBurn:test_PoolBurnRevertNotHealthy_Revert() (gas
 BurnWithFromMintTokenPool_lockOrBurn:test_PoolBurn_Success() (gas: 243568)
 BurnWithFromMintTokenPool_lockOrBurn:test_Setup_Success() (gas: 24260)
 CCIPClientTest:test_HappyPath_Success() (gas: 192504)
-CCIPClientTest:test_ccipSend_withNonNativeFeetoken_andDestTokens_Success() (gas: 325792)
-CCIPClientTest:test_ccipSend_withNonNativeFeetoken_andNoDestTokens_Success() (gas: 218834)
-CCIPClientTest:test_ccipSend_with_NativeFeeToken_andDestTokens_Success() (gas: 376797)
+CCIPClientTest:test_ccipSend_withNonNativeFeetoken_andDestTokens_Success() (gas: 326914)
+CCIPClientTest:test_ccipSend_withNonNativeFeetoken_andNoDestTokens_Success() (gas: 219955)
+CCIPClientTest:test_ccipSend_with_NativeFeeToken_andDestTokens_Success() (gas: 376823)
 CCIPClientTest:test_modifyFeeToken_Success() (gas: 74452)
 CCIPClientWithACKTest:test_ccipReceiveAndSendAck_Success() (gas: 331795)
 CCIPClientWithACKTest:test_ccipReceiver_ack_with_invalidAckMessageHeaderBytes_Revert() (gas: 438714)
@@ -703,10 +703,10 @@ OCR2Base_transmit:test_UnAuthorizedTransmitter_Revert() (gas: 23484)
 OCR2Base_transmit:test_UnauthorizedSigner_Revert() (gas: 39665)
 OCR2Base_transmit:test_WrongNumberOfSignatures_Revert() (gas: 20557)
 OnRampTokenPoolReentrancy:test_OnRampTokenPoolReentrancy_Success() (gas: 380711)
-PingPong_example_ccipReceive:test_CcipReceive_Success() (gas: 307328)
-PingPong_example_plumbing:test_Pausing_Success() (gas: 17943)
-PingPong_example_plumbing:test_typeAndVersion() (gas: 9745)
-PingPong_example_startPingPong:test_StartPingPong_Success() (gas: 234270)
+PingPong_example_ccipReceive:test_CcipReceive_Success() (gas: 179553)
+PingPong_example_plumbing:test_Pausing_Success() (gas: 17917)
+PingPong_example_plumbing:test_typeAndVersion() (gas: 9786)
+PingPong_example_startPingPong:test_StartPingPong_Success() (gas: 203446)
 PriceRegistry_applyFeeTokensUpdates:test_ApplyFeeTokensUpdates_Success() (gas: 79823)
 PriceRegistry_applyFeeTokensUpdates:test_OnlyCallableByOwner_Revert() (gas: 12580)
 PriceRegistry_constructor:test_InvalidStalenessThreshold_Revert() (gas: 67418)
@@ -853,9 +853,9 @@ Router_routeMessage:test_ManualExec_Success() (gas: 35381)
 Router_routeMessage:test_OnlyOffRamp_Revert() (gas: 25116)
 Router_routeMessage:test_WhenNotHealthy_Revert() (gas: 44724)
 Router_setWrappedNative:test_OnlyOwner_Revert() (gas: 10985)
-SelfFundedPingPong_ccipReceive:test_FundingIfNotANop_Revert() (gas: 289627)
-SelfFundedPingPong_ccipReceive:test_Funding_Success() (gas: 448499)
-SelfFundedPingPong_setCountIncrBeforeFunding:test_setCountIncrBeforeFunding() (gas: 20203)
+SelfFundedPingPong_ccipReceive:test_FundingIfNotANop_Revert() (gas: 291579)
+SelfFundedPingPong_ccipReceive:test_Funding_Success() (gas: 448569)
+SelfFundedPingPong_setCountIncrBeforeFunding:test_setCountIncrBeforeFunding() (gas: 20273)
 TokenAdminRegistry_acceptAdminRole:test_acceptAdminRole_OnlyPendingAdministrator_Revert() (gas: 51085)
 TokenAdminRegistry_acceptAdminRole:test_acceptAdminRole_Success() (gas: 43947)
 TokenAdminRegistry_addRegistryModule:test_addRegistryModule_OnlyOwner_Revert() (gas: 12629)

contracts/src/v0.8/ccip/applications/external/CCIPClient.sol

@@ -58,7 +58,7 @@ contract CCIPClient is CCIPReceiver {
     uint256 fee = IRouterClient(s_ccipRouter).getFee(destChainSelector, message);
 
     // Additional tokens for fees do not need to be approved to the router since it is already handled by setting s_feeToken
-    if (address(s_feeToken) != address(0)) {
+    if ((address(s_feeToken) != address(0)) && (s_feeToken.balanceOf(address(this)) < fee)) {
       IERC20(s_feeToken).safeTransferFrom(msg.sender, address(this), fee);
     }
 
@@ -77,6 +77,7 @@ contract CCIPClient is CCIPReceiver {
   /// @dev It has to be external because of the try/catch of ccipReceive() which invokes it
   function processMessage(Client.Any2EVMMessage calldata message)
     external
+    virtual
     override
     onlySelf
     isValidSender(message.sourceChainSelector, message.sender)

contracts/src/v0.8/ccip/applications/internal/PingPongDemo.sol

@@ -2,13 +2,13 @@
 pragma solidity ^0.8.0;
 
 import {Client} from "../../libraries/Client.sol";
-import {CCIPClientWithACK} from "../external/CCIPClientWithACK.sol";
+import {CCIPClient} from "../external/CCIPClient.sol";
 
 import {IERC20} from "../../../vendor/openzeppelin-solidity/v4.8.3/contracts/token/ERC20/IERC20.sol";
 import {SafeERC20} from "../../../vendor/openzeppelin-solidity/v4.8.3/contracts/token/ERC20/utils/SafeERC20.sol";
 
 /// @title PingPongDemo - A simple ping-pong contract for demonstrating cross-chain communication
-contract PingPongDemo is CCIPClientWithACK {
+contract PingPongDemo is CCIPClient {
   using SafeERC20 for IERC20;
 
   event Ping(uint256 pingPongCount);
@@ -24,7 +24,7 @@ contract PingPongDemo is CCIPClientWithACK {
   bool private s_isPaused;
 
   // CCIPClient will handle the token approval so there's no need to do it here
-  constructor(address router, IERC20 feeToken) CCIPClientWithACK(router, feeToken) {}
+  constructor(address router, IERC20 feeToken) CCIPClient(router, feeToken) {}
 
   function typeAndVersion() external pure virtual returns (string memory) {
     return "PingPongDemo 1.3.0";
@@ -47,7 +47,7 @@ contract PingPongDemo is CCIPClientWithACK {
     bytes memory data = abi.encode(pingPongCount);
 
     ccipSend({
-      destChainSelector: s_counterpartChainSelector, // destChaio
+      destChainSelector: s_counterpartChainSelector, // destChain
       tokenAmounts: new Client.EVMTokenAmount[](0),
       data: data
     });