I am stuck on sending TAG_BUFFER, below are logs and my code
logs
╰─$ codecrafters test
Initiating test run...
⚡ This is a turbo test run. https://codecrafters.io/turbo
Running tests. Logs should appear shortly...
[compile] Moved ./.codecrafters/run.sh → ./your_program.sh
[compile] Compilation successful.
[tester::#PV1] Running tests for Stage #PV1 (Handle APIVersions requests)
[tester::#PV1] $ ./your_program.sh /tmp/server.properties
[your_program] Server listening on port 9092 127.0.0.1:9092
[tester::#PV1] Sending "ApiVersions" (version: 4) request (Correlation id: 48288897)
[your_program] { apiKey: 18, correlationID: 48288897 }
[tester::#PV1] Received:
[tester::#PV1] Hex (bytes 20-24) | ASCII
[tester::#PV1] ------------------------------------------------+------------------
[tester::#PV1] 00 00 00 00 00 | .....
[tester::#PV1] ^ ^
[tester::#PV1] Error: Unexpected end of data
[tester::#PV1] Context:
[tester::#PV1] - ApiVersions v3
[tester::#PV1] - Response Body
[tester::#PV1] - TAG_BUFFER
[tester::#PV1] - TAGGED_FIELD_ARRAY
[tester::#PV1] - UNSIGNED_VARINT
[tester::#PV1]
[tester::#PV1] Test failed (try setting 'debug: true' in your codecrafters.yml to see more details)
My code
import net from "node:net";
/**
* Writes an unsigned variable-length integer to a buffer
* @param {Buffer} buffer - The buffer to write to
* @param {number} value - The integer value to write
* @param {number} offset - The offset in the buffer to start writing
* @returns {number} The new offset after writing
*/
function writeUnsignedVarInt(buffer, value, offset) {
let currentOffset = offset;
// Handle values that fit in a single byte (0-127)
if (value < 128) {
buffer.writeUInt8(value, currentOffset);
return currentOffset + 1;
}
// For larger values, we need multiple bytes
while (value >= 128) {
// Write 7 bits of the value + set the continuation bit (MSB)
buffer.writeUInt8((value & 0x7F) | 0x80, currentOffset);
currentOffset++;
// Shift right by 7 bits
value >>>= 7;
}
// Write the final byte (without continuation bit)
buffer.writeUInt8(value, currentOffset);
return currentOffset + 1;
}
const server = net.createServer((connection) => {
// Handle connection
connection.on("data", (data) => {
/**
* Request ArrayBuffer structure:
*
* 00 00 00 23 // message_size: 35 (4 bytes long)
* 00 12 // request_api_key: 18 (2 bytes long)
* 00 04 // request_api_version: 4 (2 bytes long)
* 6f 7f c6 61 // correlation_id: 1870644833 (4 bytes long)
*/
const apiKey = data.readUInt16BE(4);
const correlationBuffer = data.subarray(8, 12);
const correlationID = correlationBuffer.readUInt32BE(0);
console.log({ apiKey, correlationID })
/**
* Response ArrayBuffer structure:
*
* 00 00 00 12 // message_size: 18 (4 bytes long)
* 6f 7f c6 61 // correlation_id: 1870644833 (4 bytes long)
* 00 00 // error_code: 0 (2 bytes long)
* API Keys array section
*
* 00 00 00 00 // API Keys array size: 0 (4 bytes long)
*/
const responseBuffer = Buffer.alloc(28);
// Set message size
responseBuffer.writeUInt32BE(25, 0);
// Set correlation ID (same as request)
correlationBuffer.copy(responseBuffer, 4);
// Set error code
responseBuffer.writeUInt16BE(0, 8);
// Set API Keys array size
responseBuffer.writeUInt32BE(1, 10); // 4-byte size indicating 1 API key
// Add an API key entry (API key 18 - ApiVersions)
responseBuffer.writeUInt16BE(18, 14); // API key (16-bit)
responseBuffer.writeUInt16BE(0, 16); // Min version (16-bit)
responseBuffer.writeUInt16BE(4, 18); // Max version (16-bit)
// Add throttle_time_ms (required for ApiVersions v3)
responseBuffer.writeUInt32BE(0, 20);
responseBuffer.writeUInt8(0, 24);
// Send response
connection.write(responseBuffer);
})
});
server.listen(9092, "127.0.0.1", () => {
console.log("Server listening on port 9092", "127.0.0.1:9092");
});
