relayer: allow override target chain refund (#3430)

* refund address handling improvement

* fix compilation error

* Remove unnecessary line

* restrict to view

* fix comment

* Improve handling of gas limits

* get test to pass - check that the return data is appropriately long before decoding

* modification to checking inequality

* modification to checking inequality - use unchecked

* clean functions around - add untrustedBaseDeliveryPrice

* make quote_length_bytes a constant

* seperate pay into two overloads

* change inequality to equality for checking return data length

* renaming functions

* allow override of refund per gas unused

* test modification

* note

ethereum/contracts/interfaces/relayer/IWormholeRelayer.sol

@@ -380,7 +380,6 @@ interface IWormholeRelayerSend is IWormholeRelayerBase {
      * @notice *** This will only be able to succeed if the following is true **
      *         - newGasLimit >= gas limit of the old instruction
      *         - newReceiverValue >= receiver value of the old instruction
-     *         - newDeliveryProvider's `targetChainRefundPerGasUnused` >= old relay provider's `targetChainRefundPerGasUnused`
      */
     function resendToEvm(
         VaaKey memory deliveryVaaKey,
@@ -427,7 +426,10 @@ interface IWormholeRelayerSend is IWormholeRelayerBase {
      * @param gasLimit gas limit with which to call `targetAddress`. 
      * @return nativePriceQuote Price, in units of current chain currency, that the delivery provider charges to perform the relay
      * @return targetChainRefundPerGasUnused amount of target chain currency that will be refunded per unit of gas unused, 
-     *         if a refundAddress is specified
+     *         if a refundAddress is specified. 
+     *         Note: This value can be overridden by the delivery provider on the target chain. The returned value here should be considered to be a 
+     *         promise by the delivery provider of the amount of refund per gas unused that will be returned to the refundAddress at the target chain. 
+     *         If a delivery provider decides to override, this will be visible as part of the emitted Delivery event on the target chain. 
      */
     function quoteEVMDeliveryPrice(
         uint16 targetChain,
@@ -445,6 +447,9 @@ interface IWormholeRelayerSend is IWormholeRelayerBase {
      * @return nativePriceQuote Price, in units of current chain currency, that the delivery provider charges to perform the relay
      * @return targetChainRefundPerGasUnused amount of target chain currency that will be refunded per unit of gas unused, 
      *         if a refundAddress is specified
+     *         Note: This value can be overridden by the delivery provider on the target chain. The returned value here should be considered to be a 
+     *         promise by the delivery provider of the amount of refund per gas unused that will be returned to the refundAddress at the target chain. 
+     *         If a delivery provider decides to override, this will be visible as part of the emitted Delivery event on the target chain.
      */
     function quoteEVMDeliveryPrice(
         uint16 targetChain,

ethereum/contracts/interfaces/relayer/IWormholeRelayerTyped.sol

@@ -382,7 +382,6 @@ interface IWormholeRelayerSend is IWormholeRelayerBase {
      * @notice *** This will only be able to succeed if the following is true **
      *         - newGasLimit >= gas limit of the old instruction
      *         - newReceiverValue >= receiver value of the old instruction
-     *         - newDeliveryProvider's `targetChainRefundPerGasUnused` >= old relay provider's `targetChainRefundPerGasUnused`
      */
     function resendToEvm(
         VaaKey memory deliveryVaaKey,
@@ -429,7 +428,10 @@ interface IWormholeRelayerSend is IWormholeRelayerBase {
      * @param gasLimit gas limit with which to call `targetAddress`. 
      * @return nativePriceQuote Price, in units of current chain currency, that the delivery provider charges to perform the relay
      * @return targetChainRefundPerGasUnused amount of target chain currency that will be refunded per unit of gas unused, 
-     *         if a refundAddress is specified
+     *         if a refundAddress is specified. 
+     *         Note: This value can be overridden by the delivery provider on the target chain. The returned value here should be considered to be a 
+     *         promise by the delivery provider of the amount of refund per gas unused that will be returned to the refundAddress at the target chain. 
+     *         If a delivery provider decides to override, this will be visible as part of the emitted Delivery event on the target chain. 
      */
     function quoteEVMDeliveryPrice(
         uint16 targetChain,
@@ -447,6 +449,9 @@ interface IWormholeRelayerSend is IWormholeRelayerBase {
      * @return nativePriceQuote Price, in units of current chain currency, that the delivery provider charges to perform the relay
      * @return targetChainRefundPerGasUnused amount of target chain currency that will be refunded per unit of gas unused, 
      *         if a refundAddress is specified
+     *         Note: This value can be overridden by the delivery provider on the target chain. The returned value here should be considered to be a 
+     *         promise by the delivery provider of the amount of refund per gas unused that will be returned to the refundAddress at the target chain. 
+     *         If a delivery provider decides to override, this will be visible as part of the emitted Delivery event on the target chain.
      */
     function quoteEVMDeliveryPrice(
         uint16 targetChain,

ethereum/contracts/relayer/wormholeRelayer/WormholeRelayerDelivery.sol

@@ -12,7 +12,6 @@ import {
     VaaKeysDoNotMatchVaas,
     InvalidOverrideGasLimit,
     InvalidOverrideReceiverValue,
-    InvalidOverrideRefundPerGasUnused,
     RequesterNotWormholeRelayer,
     DeliveryProviderCannotReceivePayment,
     MessageKey,
@@ -219,12 +218,6 @@ abstract contract WormholeRelayerDelivery is WormholeRelayerBase, IWormholeRelay
             decodeEvmExecutionInfoV1(deliveryOverrides.newExecutionInfo);
         deliveryOverridesReceiverValue = deliveryOverrides.newReceiverValue;
 
-        if (
-            deliveryOverridesExecutionInfo.targetChainRefundPerGasUnused.unwrap()
-                < executionInfo.targetChainRefundPerGasUnused.unwrap()
-        ) {
-            revert InvalidOverrideRefundPerGasUnused();
-        }
         if (deliveryOverridesExecutionInfo.gasLimit < executionInfo.gasLimit) {
             revert InvalidOverrideGasLimit();
         }

ethereum/forge-test/relayer/WormholeRelayer.t.sol

@@ -1843,7 +1843,7 @@ contract WormholeRelayerTests is Test {
         );
     }
 
-    function testRevertDeliveryWithOverrideMaximumRefund(
+    function testAllowDeliveryWithOverrideMaximumRefund(
         GasParameters memory gasParams,
         FeeParameters memory feeParams,
         bytes memory message
@@ -1877,7 +1877,6 @@ contract WormholeRelayerTests is Test {
             stack.deliveryVaaHash //really redeliveryHash
         );
 
-        vm.expectRevert(abi.encodeWithSignature("InvalidOverrideRefundPerGasUnused()"));
         setup.target.coreRelayerFull.deliver{value: stack.budget}(
             stack.encodedVMs,
             stack.encodedDeliveryVAA,