Method _handleTcpData

src/network.js:177–206

* Handle TCP data from main thread * @private

(msg)

     * @private
     */
    _handleTcpData(msg) {
        const { key, data } = msg;
        const session = this.natTable.get(key);
        if (!session) return;
        
        const payload = Buffer.from(data);
        
        // MTU is 1500, IP header is 20, TCP header is 20
        // Maximum Segment Size (MSS) = 1500 - 20 - 20 = 1460
        const MSS = 1460;
        
        // Segment the data if it exceeds MSS
        let offset = 0;
        while (offset < payload.length) {
            const chunkSize = Math.min(MSS, payload.length - offset);
            const chunk = payload.subarray(offset, offset + chunkSize);
            const isLast = (offset + chunkSize >= payload.length);
            
            // Send PSH-ACK for last segment, just ACK for intermediate segments
            const flags = isLast ? 0x18 : 0x10; // PSH|ACK or just ACK
            this.sendTCP(session.srcIP, session.srcPort, session.dstIP, session.dstPort,
                         session.mySeq, session.myAck, flags, chunk);
            session.mySeq += chunk.length;
            offset += chunkSize;
        }
        
        // Note: Flow control is handled by ring buffer backpressure in main thread.
        // When ring buffer is full, main thread pauses socket and buffers data.
        // No need for worker-side txBuffer flow control - it would cause deadlocks.
    }
    
    /**
     * Handle TCP end (FIN from remote) from main thread