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fix: use flag-anchored positioning for MULTIPLE commission decode #26

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fix: use flag-anchored positioning for MULTIPLE commission decode #26

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53 changes: 30 additions & 23 deletions src/scripts/decode/decode_commission.js
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Original file line number Diff line number Diff line change
Expand Up @@ -199,38 +199,45 @@ function extractCommissionInfoFromCalldata(calldataHex) {
// Try MULTIPLE commission (3-8 referrers)
// Structure: [commissionN]...[commission2][middle][commission1]
// The referrer count is encoded in the middle block's second byte
// Middle block is always at: calldatasize - 0x40 (second-to-last block)
// Middle block position is derived from flag position, not calldataHex.length,
// so that arbitrary data appended after commission data doesn't affect parsing.
// ========================================================================
for (const flag of ['0x88880afc2aaa', '0x88880afc2bbb']) {
const flagHex = flag.replace(/^0x/, '');
const flagIndex = calldataHex.indexOf(flagHex);

if (flagIndex === -1) continue;

// Check if we have at least 4 blocks (minimum for MULTIPLE with 3 referrers)
if (calldataHex.length < BYTE_SIZE.BLOCK * 4) continue;


try {
// Middle block is always second-to-last (at offset 0x40 from end)
// In hex chars: calldataHex.length - 128 to calldataHex.length - 64
const middleStart = calldataHex.length - (BYTE_SIZE.BLOCK * 2);
const middleBlock = '0x' + calldataHex.slice(middleStart, middleStart + BYTE_SIZE.BLOCK);
const referrerNum = parseReferrerNumFromMiddle(middleBlock);

// Validate referrer count
if (referrerNum < MIN_COMMISSION_MULTIPLE_NUM || referrerNum > MAX_COMMISSION_MULTIPLE_NUM) {
continue;
// Try each possible referrerNum (3-8) and validate against the middle block
// Layout: [commissionN][commission_{N-1}]...[commission_2][middle][commission_1]
// commissionN starts at flagIndex, so:
// middle is at: flagIndex + (referrerNum - 1) * BYTE_SIZE.BLOCK
// commission_1 is at: flagIndex + referrerNum * BYTE_SIZE.BLOCK
let referrerNum = 0;
let totalBlocks = 0;

for (let tryNum = MIN_COMMISSION_MULTIPLE_NUM; tryNum <= MAX_COMMISSION_MULTIPLE_NUM; tryNum++) {
const middleStart = flagIndex + (tryNum - 1) * BYTE_SIZE.BLOCK;

// Check if we have enough data for middle + commission_1
if (middleStart + BYTE_SIZE.BLOCK * 2 > calldataHex.length) continue;

const middleBlock = '0x' + calldataHex.slice(middleStart, middleStart + BYTE_SIZE.BLOCK);
const candidateNum = parseReferrerNumFromMiddle(middleBlock);

if (candidateNum === tryNum) {
referrerNum = tryNum;
totalBlocks = tryNum + 1; // N commissions + 1 middle
break;
}
}

// Calculate total block count: referrerNum commissions + 1 middle
const totalBlocks = referrerNum + 1;

// Verify we have enough data
if (calldataHex.length < BYTE_SIZE.BLOCK * totalBlocks) continue;


if (referrerNum === 0) continue;

// Extract blocks using findFlagAndExtractBlocks
const result = findFlagAndExtractBlocks(calldataHex, flagHex, totalBlocks);

if (!result) continue;

// Build return object with ordinal names
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