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fix: update writeVerificationHash to correctly insert HMAC-MD5 hash in packet structure

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MayaTheShy
2025-11-10 01:29:18 -05:00
parent 861407c043
commit 6bfce1ff79
1 changed files with 19 additions and 15 deletions
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34
src/NLPacketCodec.cpp
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@@ -134,28 +134,32 @@ void NLPacket::writeVerificationHash(const uint8_t* connectionSecretUUID) {
} }
const size_t HASH_SIZE = 16; // MD5 produces 16 bytes const size_t HASH_SIZE = 16; // MD5 produces 16 bytes
const size_t HASH_OFFSET = SOURCED_HEADER_SIZE; // Hash goes right after source ID const size_t HASH_OFFSET = SOURCED_HEADER_SIZE; // Hash goes right after source ID (offset 8)
// Calculate HMAC-MD5 hash // The current packet structure is: [header(8)] [payload...]
// The hash is calculated over the payload data AFTER the hash field itself // We need to insert 16 bytes for the hash between header and payload
const size_t payloadOffset = HASH_OFFSET + HASH_SIZE; // New structure will be: [header(8)] [hash(16)] [payload...]
const uint8_t* payloadData = m_data.data() + payloadOffset;
const size_t payloadSize = m_data.size() - payloadOffset;
// Get the current payload (everything after the header)
std::vector<uint8_t> currentPayload(m_data.begin() + m_headerSize, m_data.end());
// Resize packet to make room for hash
m_data.resize(m_headerSize + HASH_SIZE + currentPayload.size());
// Move payload to after the hash slot
if (!currentPayload.empty()) {
std::memcpy(m_data.data() + HASH_OFFSET + HASH_SIZE, currentPayload.data(), currentPayload.size());
}
// Calculate HMAC-MD5 hash over the payload data
unsigned char hash[HASH_SIZE]; unsigned char hash[HASH_SIZE];
unsigned int hashLen = HASH_SIZE; unsigned int hashLen = HASH_SIZE;
// Use HMAC_MD5 with connection secret UUID as key // Use HMAC_MD5 with connection secret UUID as key
HMAC(EVP_md5(), connectionSecretUUID, 16, payloadData, payloadSize, hash, &hashLen); HMAC(EVP_md5(), connectionSecretUUID, 16, currentPayload.data(), currentPayload.size(), hash, &hashLen);
// Insert hash into packet at correct position // Write hash into the reserved slot
// We need to insert 16 bytes right after the header std::memcpy(m_data.data() + HASH_OFFSET, hash, HASH_SIZE);
if (m_data.size() < HASH_OFFSET + HASH_SIZE) {
m_data.resize(HASH_OFFSET + HASH_SIZE);
}
// Insert hash at the correct position
m_data.insert(m_data.begin() + HASH_OFFSET, hash, hash + HASH_SIZE);
} }
bool NLPacket::parseHeader(const uint8_t* data, size_t size, Header& header) { bool NLPacket::parseHeader(const uint8_t* data, size_t size, Header& header) {