feat: cleanup and streamline webssh capability

internal/hp_ipn/ssh.go

@@ -0,0 +1,184 @@
+//go:build js && wasm
+
+package hp_ipn
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+	"log"
+	"net"
+	"time"
+
+	"golang.org/x/crypto/ssh"
+)
+
+// Represents an SSH session over the Tailnet.
+type SSHSession struct {
+	// Hostname on the Tailnet.
+	Hostname string
+
+	// Username for the SSH connection.
+	Username string
+
+	// Xterm configuration for the SSH session.
+	TermConfig *SSHXtermConfig
+
+	// Handle to the current IPN connection.
+	Ipn *TsWasmIpn
+
+	// Handle to the current SSH session.
+	Pty *ssh.Session
+
+	// Tracks resize notifications for rows.
+	ResizeRows int
+
+	// Tracks resize notifications for columns.
+	ResizeCols int
+}
+
+// Creates a new SSH session given a hostname and username.
+func (i *TsWasmIpn) NewSSHSession(hostname, username string, termConfig *SSHXtermConfig) *SSHSession {
+	return &SSHSession{
+		Hostname:   hostname,
+		Username:   username,
+		TermConfig: termConfig,
+		Ipn:        i,
+	}
+}
+
+func (s *SSHSession) ConnectAndRun() {
+	defer s.TermConfig.OnDisconnect()
+
+	// Default to a 5 second timeout for the connection AFTER dial.
+	ctx, cancel := context.WithTimeout(context.Background(), 15*time.Second)
+	defer cancel()
+
+	// TODO: Log here
+	log.Printf("Attempting SSH dial to host: %s", net.JoinHostPort(s.Hostname, "22"))
+	conn, err := s.Ipn.dialer.UserDial(ctx, "tcp", net.JoinHostPort(s.Hostname, "22"))
+	if err != nil {
+		log.Printf("SSH dial error: %v", err)
+		s.writeError("Dial", err)
+		return
+	}
+
+	defer conn.Close()
+	sshConf := &ssh.ClientConfig{
+		User: s.Username,
+		HostKeyCallback: func(hostname string, remote net.Addr, key ssh.PublicKey) error {
+			// Tailscale SSH doesn't use host keys
+			// TODO: Log that the connection was established
+			return nil
+		},
+	}
+
+	// TODO: LOG: Starting SSH Client
+	sshConn, _, _, err := ssh.NewClientConn(conn, s.Hostname, sshConf)
+	if err != nil {
+		s.writeError("SSH", err)
+		return
+	}
+
+	defer sshConn.Close()
+	sshClient := ssh.NewClient(sshConn, nil, nil)
+	defer sshClient.Close()
+
+	pty, err := sshClient.NewSession()
+	if err != nil {
+		s.writeError("SSH", err)
+		return
+	}
+
+	defer pty.Close()
+	s.Pty = pty
+
+	pty.Stdout = XtermPipe{s.TermConfig.OnStdout}
+	pty.Stderr = XtermPipe{s.TermConfig.OnStdout}
+
+	// TODO: Set Stdin func
+	stdin, err := pty.StdinPipe()
+	if err != nil {
+		s.writeError("SSH", err)
+		return
+	}
+
+	s.TermConfig.PassStdinHandler(func(input string) {
+		_, err := stdin.Write([]byte(input))
+		if err != nil {
+			s.writeError("SSH", err)
+			return
+		}
+	})
+
+	rows := s.TermConfig.Rows
+	if s.ResizeRows != 0 {
+		rows = s.ResizeRows
+	}
+
+	cols := s.TermConfig.Cols
+	if s.ResizeCols != 0 {
+		cols = s.ResizeCols
+	}
+
+	err = pty.RequestPty("xterm", rows, cols, ssh.TerminalModes{})
+	if err != nil {
+		s.writeError("SSH", err)
+		return
+	}
+
+	err = pty.Shell()
+	if err != nil {
+		s.writeError("SSH", err)
+		return
+	}
+
+	s.TermConfig.OnConnect()
+	err = pty.Wait()
+	if err != nil {
+		s.writeError("SSH", err)
+		return
+	}
+}
+
+// Resize resizes the terminal for the SSH session.
+// TODO: This does NOT work correctly from Xterm.js
+func (s *SSHSession) Resize(rows, cols int) error {
+	// Used to handle resizes while still connecting.
+	if s.Pty == nil {
+		s.ResizeRows = rows
+		s.ResizeCols = cols
+		return nil
+	}
+
+	return s.Pty.WindowChange(rows, cols)
+}
+
+// Closes the SSH session.
+func (s *SSHSession) Close() error {
+	if s.Pty == nil {
+		return nil
+	}
+
+	return s.Pty.Close()
+}
+
+// Quick easy formatter for writing errors to the terminal.
+func (s *SSHSession) writeError(label string, err error) {
+	o := fmt.Sprintf("%s error: %v\r\n", label, err)
+	s.TermConfig.OnStderr(o)
+}
+
+// io.Writer "emulator" to pass to the ssh module.
+type XtermPipe struct {
+	// Function to call when data is written.
+	Send func(data string)
+}
+
+// Write implements the io.Writer interface for XtermPipe.
+func (x XtermPipe) Write(data []byte) (int, error) {
+	// Tailscale's webSSH does this to fix issues in xterm.js
+	res := bytes.Replace(data, []byte("\n"), []byte("\n\r"), -1)
+	x.Send(string(res))
+	return len(data), nil
+}