plain tcp proxy for db

main.go

package main

import (
	"io"
	"log"
	"net"
	"sync"

	"github.com/denisenkom/go-mssqldb/msdsn"
)

// Configuration
const (
	proxyListenAddr = ":1434"     // Default MSSQL port
	targetDBAddr    = "localhost" // Without port
	targetDBPort    = 1433
	dbUser          = "sa"
	dbPassword      = "SomeRandPass123"
	dbName          = "master"
)

func main() {
	// Start listening for incoming MSSQL connections
	listener, err := net.Listen("tcp", proxyListenAddr)
	if err != nil {
		log.Fatalf("Failed to listen: %v", err)
	}
	defer listener.Close()

	log.Printf("MSSQL proxy server listening on %s", proxyListenAddr)

	for {
		// Accept incoming client connections
		clientConn, err := listener.Accept()
		if err != nil {
			log.Printf("Error accepting connection: %v", err)
			continue
		}

		// Handle each connection in a separate goroutine
		go handleClientConnection(clientConn)
	}
}

func handleClientConnection(clientConn net.Conn) {
	defer clientConn.Close()

	// Create connection config (not used directly but kept for reference)
	_ = msdsn.Config{
		Host:       targetDBAddr,
		Port:       targetDBPort,
		User:       dbUser,
		Password:   dbPassword,
		Database:   dbName,
		Encryption: msdsn.EncryptionDisabled, // Adjust as needed
	}

	// Connect to the target MSSQL server
	targetConn, err := net.Dial("tcp", net.JoinHostPort(targetDBAddr, "1433"))
	if err != nil {
		log.Printf("Failed to connect to target DB: %v", err)
		return
	}
	defer targetConn.Close()

	log.Printf("Proxy established connection from %s to %s",
		clientConn.RemoteAddr(), targetConn.RemoteAddr())

	// Use wait groups to wait for both directions to complete
	var wg sync.WaitGroup
	wg.Add(2)

	// Forward data from client to DB server
	go func() {
		defer wg.Done()
		_, err := io.Copy(targetConn, clientConn)
		if err != nil {
			log.Printf("Client->DB copy error: %v", err)
		}
	}()

	// Forward data from DB server to client
	go func() {
		defer wg.Done()
		_, err := io.Copy(clientConn, targetConn)
		if err != nil {
			log.Printf("DB->Client copy error: %v", err)
		}
	}()

	// Wait for both directions to complete
	wg.Wait()
}