fix: use fixed-length array for priceIds in req

Author: cctdaniel

target_chains/ethereum/contracts/contracts/pulse/Pulse.sol

@@ -31,6 +31,11 @@ abstract contract Pulse is IPulse, PulseState {
                 req.publishTime = 1;
                 req.callbackGasLimit = 1;
                 req.requester = address(1);
+                req.numPriceIds = 0;
+                // Pre-warm the priceIds array storage
+                for (uint8 j = 0; j < MAX_PRICE_IDS; j++) {
+                    req.priceIds[j] = bytes32(0);
+                }
             }
         }
     }
@@ -41,6 +46,9 @@ abstract contract Pulse is IPulse, PulseState {
         uint256 callbackGasLimit
     ) external payable override returns (uint64 requestSequenceNumber) {
         require(publishTime <= block.timestamp + 60, "Too far in future");
+        if (priceIds.length > MAX_PRICE_IDS) {
+            revert TooManyPriceIds(priceIds.length, MAX_PRICE_IDS);
+        }
         requestSequenceNumber = _state.currentSequenceNumber++;
 
         uint128 requiredFee = getFee(callbackGasLimit);
@@ -49,9 +57,14 @@ abstract contract Pulse is IPulse, PulseState {
         Request storage req = allocRequest(requestSequenceNumber);
         req.sequenceNumber = requestSequenceNumber;
         req.publishTime = publishTime;
-        req.priceIdsHash = keccak256(abi.encode(priceIds));
         req.callbackGasLimit = callbackGasLimit;
         req.requester = msg.sender;
+        req.numPriceIds = uint8(priceIds.length);
+
+        // Copy price IDs to storage
+        for (uint8 i = 0; i < priceIds.length; i++) {
+            req.priceIds[i] = priceIds[i];
+        }
 
         _state.accruedFeesInWei += SafeCast.toUint128(msg.value);
 
@@ -66,10 +79,14 @@ abstract contract Pulse is IPulse, PulseState {
         Request storage req = findActiveRequest(sequenceNumber);
 
         // Verify priceIds match
-        bytes32 providedPriceIdsHash = keccak256(abi.encode(priceIds));
-        bytes32 storedPriceIdsHash = req.priceIdsHash;
-        if (providedPriceIdsHash != storedPriceIdsHash) {
-            revert InvalidPriceIds(providedPriceIdsHash, storedPriceIdsHash);
+        require(
+            priceIds.length == req.numPriceIds,
+            "Price IDs length mismatch"
+        );
+        for (uint8 i = 0; i < req.numPriceIds; i++) {
+            if (priceIds[i] != req.priceIds[i]) {
+                revert InvalidPriceIds(priceIds[i], req.priceIds[i]);
+            }
         }
 
         // Parse price feeds first to measure gas usage

target_chains/ethereum/contracts/contracts/pulse/PulseErrors.sol

@@ -12,3 +12,4 @@ error InvalidPriceIds(bytes32 providedPriceIdsHash, bytes32 storedPriceIdsHash);
 error InvalidCallbackGasLimit(uint256 requested, uint256 stored);
 error ExceedsMaxPrices(uint32 requested, uint32 maxAllowed);
 error InsufficientGas();
+error TooManyPriceIds(uint256 provided, uint256 maximum);

target_chains/ethereum/contracts/contracts/pulse/PulseState.sol

@@ -5,11 +5,13 @@ pragma solidity ^0.8.0;
 contract PulseState {
     uint8 public constant NUM_REQUESTS = 32;
     bytes1 public constant NUM_REQUESTS_MASK = 0x1f;
+    uint8 public constant MAX_PRICE_IDS = 10;
 
     struct Request {
         uint64 sequenceNumber;
         uint256 publishTime;
-        bytes32 priceIdsHash;
+        bytes32[MAX_PRICE_IDS] priceIds;
+        uint8 numPriceIds; // Actual number of price IDs used
         uint256 callbackGasLimit;
         address requester;
     }