108 lines
2.8 KiB
Go
108 lines
2.8 KiB
Go
package main
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import (
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"fmt"
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"io"
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"log/slog"
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"net"
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"sync"
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"golang.org/x/crypto/ssh"
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)
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type PortForwarder struct {
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sshCon *ssh.Client
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localPort string
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remotePort string
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remoteHost string
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logMutex sync.Mutex
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}
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func NewPortForwarder(sshCon *ssh.Client, localPort, remotePort, remoteHost string) *PortForwarder {
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return &PortForwarder{
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sshCon: sshCon,
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localPort: localPort,
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remotePort: remotePort,
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remoteHost: remoteHost,
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}
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}
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func (pf *PortForwarder) forward() error {
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localAddr := "127.0.0.1:" + pf.localPort
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remoteAddr := net.JoinHostPort(pf.remoteHost, pf.remotePort)
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pf.logf("INFO", "Starting port forwarder: local %s -> remote %s (via SSH)", localAddr, remoteAddr)
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listener, err := net.Listen("tcp", localAddr)
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if err != nil {
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pf.logf("ERROR", "Failed to open local listener on %s: %v", localAddr, err)
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return fmt.Errorf("failed to listen on %s: %w", localAddr, err)
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}
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defer listener.Close()
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pf.logf("INFO", fmt.Sprintf("Listener active on %s", localAddr))
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for {
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localConn, err := listener.Accept()
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if err != nil {
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if opErr, ok := err.(*net.OpError); ok && opErr.Err.Error() == "use of closed network connection" {
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pf.logf("INFO", "Listener on %s closed, stopping forwarder.", localAddr)
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return nil
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}
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pf.logf("ERROR", "Failed to accept incoming connection on %s: %v", localAddr, err)
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continue
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}
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pf.logf("INFO", fmt.Sprintf("Accepted connection from %s on %s", localConn.RemoteAddr(), localAddr))
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go pf.handleConnection(localConn, remoteAddr)
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}
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}
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func (pf *PortForwarder) handleConnection(localConn net.Conn, remoteAddr string) {
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defer localConn.Close()
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pf.logf("INFO", "Dialing remote host %s via SSH tunnel for %s", remoteAddr, localConn.RemoteAddr())
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remoteConn, err := pf.sshCon.Dial("tcp", remoteAddr)
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if err != nil {
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pf.logf("ERROR", "Failed to dial remote host %s via SSH: %v", remoteAddr, err)
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return
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}
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defer remoteConn.Close()
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pf.logf("INFO", "Connection to %s established. Starting data copy.", remoteAddr)
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var wg sync.WaitGroup
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wg.Add(2)
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go func() {
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defer wg.Done()
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defer localConn.Close()
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bytesCopied, err := io.Copy(localConn, remoteConn)
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if err != nil {
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}
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pf.logf("INFO", "Finished copying remote->local (%d bytes) for %s", bytesCopied, localConn.RemoteAddr())
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}()
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go func() {
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defer wg.Done()
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defer remoteConn.Close()
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bytesCopied, err := io.Copy(remoteConn, localConn)
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if err != nil {
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}
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pf.logf("INFO", "Finished copying local->remote (%d bytes) for %s", bytesCopied, localConn.RemoteAddr())
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}()
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wg.Wait()
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pf.logf("INFO", "Closing forwarded connection for %s", localConn.RemoteAddr())
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}
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func (pf *PortForwarder) logf(level, format string, v ...any) {
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pf.logMutex.Lock()
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defer pf.logMutex.Unlock()
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switch level {
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case "INFO":
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slog.Info(format, v...)
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case "WARN":
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slog.Warn(format, v...)
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case "ERROR":
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slog.Error(format, v...)
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}
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}
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