init commit

internal/network/tcp_server.go

@@ -0,0 +1,180 @@
+package network
+
+import (
+	"bytes"
+	"crypto/rand"
+	"crypto/rsa"
+	"crypto/tls"
+	"crypto/x509"
+	"crypto/x509/pkix"
+	"customServer/internal/handlers"
+	"customServer/internal/protocol"
+	"fmt"
+	"io"
+	"math/big"
+	"net"
+	"time"
+)
+
+func StartTCPServer(addr string) error {
+	tlsConfig, err := generateSelfSignedCert()
+	if err != nil {
+		return fmt.Errorf("failed to generate self-signed cert: %v", err)
+	}
+
+	listener, err := tls.Listen("tcp", addr, tlsConfig)
+	if err != nil {
+		return fmt.Errorf("TCP TLS listener failed: %v", err)
+	}
+	fmt.Printf("[TCP] Scalable Server (TLS): localhost%s\n", addr)
+
+	for {
+		conn, err := listener.Accept()
+		if err != nil {
+			fmt.Printf("Accept error: %v\n", err)
+			continue
+		}
+		go handleTCPConnection(conn)
+	}
+}
+
+func handleTCPConnection(conn net.Conn) {
+	defer conn.Close()
+	fmt.Printf("[TCP] New TLS connection from %s\n", conn.RemoteAddr())
+
+	for {
+		// Read length (4 bytes, Big Endian)
+		length, err := protocol.ReadPacketLength(conn)
+		if err != nil {
+			if err != io.EOF {
+				fmt.Printf("[TCP] Read length error: %v\n", err)
+			}
+			return
+		}
+
+		// Read packet
+		data := make([]byte, length)
+		_, err = io.ReadFull(conn, data)
+		if err != nil {
+			fmt.Printf("[TCP] Read data error: %v\n", err)
+			return
+		}
+
+		fmt.Printf("[TCP] Received packet of %d bytes\n", length)
+
+		packetID := int64(0)
+		requestNumber := int32(0)
+		var payloadBytes []byte
+
+		reader := bytes.NewReader(data)
+		for {
+			tag, err := protocol.ReadVarint(reader)
+			if err != nil {
+				break
+			}
+			fieldNum := tag >> 3
+			wireType := tag & 0x7
+
+			if fieldNum == 1 && wireType == 0 { // Packet.id
+				packetID, _ = protocol.ReadVarintInt64(reader)
+			} else if fieldNum == 3 && wireType == 2 { // Packet.payload (Message)
+				payloadLen, _ := protocol.ReadVarint(reader)
+				payloadBytes = make([]byte, payloadLen)
+				reader.Read(payloadBytes)
+
+				payloadReader := bytes.NewReader(payloadBytes)
+				for {
+					pTag, err := protocol.ReadVarint(payloadReader)
+					if err != nil {
+						break
+					}
+					pFieldNum := pTag >> 3
+					pWireType := pTag & 0x7
+					if pFieldNum == 1 && pWireType == 0 { // Message.request_number
+						reqNum64, _ := protocol.ReadVarintInt64(payloadReader)
+						requestNumber = int32(reqNum64)
+					} else {
+						protocol.SkipField(payloadReader, pWireType)
+					}
+				}
+			} else {
+				protocol.SkipField(reader, wireType)
+			}
+		}
+
+		fmt.Printf("[TCP] Got Request ID: %d, Number: %d\n", packetID, requestNumber)
+
+		responsePayload, responseFieldNum := handlers.Dispatch(conn, packetID, requestNumber, payloadBytes)
+		if responsePayload != nil {
+			sendTCPResponse(conn, packetID, responseFieldNum, responsePayload)
+		}
+	}
+}
+
+func sendTCPResponse(conn net.Conn, packetID int64, fieldNum int, payload []byte) {
+	// Construct Message wrapper
+	message := make([]byte, 0)
+	// Field 1: request_number
+	message = append(message, 0x08)
+	message = append(message, protocol.EncodeVarint(uint64(fieldNum))...)
+
+	// Field [fieldNum]: payload (WireType 2)
+	message = append(message, protocol.EncodeVarint(uint64(fieldNum<<3|2))...)
+	message = append(message, protocol.EncodeVarint(uint64(len(payload)))...)
+	message = append(message, payload...)
+
+	// Construct Packet wrapper
+	packet := make([]byte, 0)
+	// Field 1: Id
+	packet = append(packet, 0x08)
+	packet = append(packet, protocol.EncodeVarint(uint64(packetID))...)
+	// Field 3: Payload
+	packet = append(packet, 0x1a)
+	packet = append(packet, protocol.EncodeVarint(uint64(len(message)))...)
+	packet = append(packet, message...)
+
+	// Send length + packet
+	lengthBuf := make([]byte, 4)
+	length := uint32(len(packet))
+	lengthBuf[0] = byte(length >> 24)
+	lengthBuf[1] = byte(length >> 16)
+	lengthBuf[2] = byte(length >> 8)
+	lengthBuf[3] = byte(length)
+
+	conn.Write(lengthBuf)
+	conn.Write(packet)
+}
+
+func generateSelfSignedCert() (*tls.Config, error) {
+	priv, err := rsa.GenerateKey(rand.Reader, 2048)
+	if err != nil {
+		return nil, err
+	}
+
+	template := x509.Certificate{
+		SerialNumber: big.NewInt(1),
+		Subject: pkix.Name{
+			Organization: []string{"Custom Server Mod"},
+		},
+		NotBefore: time.Now(),
+		NotAfter:  time.Now().Add(time.Hour * 24 * 365),
+
+		KeyUsage:              x509.KeyUsageKeyEncipherment | x509.KeyUsageDigitalSignature,
+		ExtKeyUsage:           []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth},
+		BasicConstraintsValid: true,
+		IPAddresses:           []net.IP{net.ParseIP("127.0.0.1")},
+		DNSNames:              []string{"localhost"},
+	}
+
+	derBytes, err := x509.CreateCertificate(rand.Reader, &template, &template, &priv.PublicKey, priv)
+	if err != nil {
+		return nil, err
+	}
+
+	cert := tls.Certificate{
+		Certificate: [][]byte{derBytes},
+		PrivateKey:  priv,
+	}
+
+	return &tls.Config{Certificates: []tls.Certificate{cert}}, nil
+}