mirror of
https://github.com/fosrl/newt.git
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91 lines
2.4 KiB
Go
91 lines
2.4 KiB
Go
package browsergateway
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import (
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"context"
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"encoding/json"
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"fmt"
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"log"
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"github.com/coder/websocket"
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"github.com/fosrl/newt/nativessh"
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)
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// NativeSSHConfig holds configuration for the native PTY/shell mode.
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type NativeSSHConfig struct {
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// Shell is the executable to spawn (e.g. /bin/bash). Defaults to /bin/sh.
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Shell string
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}
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// serveNativeSSHSession handles a WebSocket SSH session by spawning a local
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// PTY+shell instead of proxying to an external SSH server. The auth token has
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// already been validated at the WebSocket upgrade level, so this function only
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// reads (and discards) the initial "auth" frame for protocol compatibility with
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// the browser client before starting the shell.
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func serveNativeSSHSession(ctx context.Context, ws *websocket.Conn, cfg NativeSSHConfig) error {
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// Read and discard the auth frame (token already validated at HTTP layer).
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_, authBytes, err := ws.Read(ctx)
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if err != nil {
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return fmt.Errorf("read auth message: %w", err)
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}
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var authMsg sshClientMsg
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if err := json.Unmarshal(authBytes, &authMsg); err != nil || authMsg.Type != "auth" {
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return fmt.Errorf("expected auth message, got: %s", authBytes)
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}
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log.Printf("SSH native: spawning shell")
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sess, err := nativessh.NewPTYSession()
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if err != nil {
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sendSSHError(ctx, ws, fmt.Sprintf("Failed to spawn shell: %v", err))
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return fmt.Errorf("pty session: %w", err)
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}
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defer sess.Close()
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// Cancel context to unblock the WebSocket read loop when the shell exits.
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sessCtx, cancelSess := context.WithCancel(ctx)
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defer cancelSess()
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// Pump PTY output → WebSocket.
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go func() {
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defer cancelSess()
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buf := make([]byte, 4096)
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for {
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n, readErr := sess.Read(buf)
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if n > 0 {
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msg := sshServerMsg{Type: "data", Data: string(buf[:n])}
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b, _ := json.Marshal(msg)
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if writeErr := ws.Write(sessCtx, websocket.MessageText, b); writeErr != nil {
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return
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}
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}
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if readErr != nil {
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return
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}
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}
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}()
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// Pump WebSocket input → PTY stdin / resize.
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for {
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_, msgBytes, readErr := ws.Read(sessCtx)
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if readErr != nil {
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break
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}
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var msg sshClientMsg
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if err := json.Unmarshal(msgBytes, &msg); err != nil {
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continue
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}
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switch msg.Type {
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case "data":
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if _, writeErr := sess.Write([]byte(msg.Data)); writeErr != nil {
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return fmt.Errorf("write pty: %w", writeErr)
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}
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case "resize":
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if msg.Cols > 0 && msg.Rows > 0 {
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_ = sess.Resize(uint16(msg.Cols), uint16(msg.Rows))
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}
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}
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}
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return nil
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}
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