157 lines
5.1 KiB
Go
157 lines
5.1 KiB
Go
package ssh
|
|
|
|
import (
|
|
"crypto/subtle"
|
|
"net"
|
|
|
|
gossh "github.com/tailscale/golang-x-crypto/ssh"
|
|
)
|
|
|
|
type Signal string
|
|
|
|
// POSIX signals as listed in RFC 4254 Section 6.10.
|
|
const (
|
|
SIGABRT Signal = "ABRT"
|
|
SIGALRM Signal = "ALRM"
|
|
SIGFPE Signal = "FPE"
|
|
SIGHUP Signal = "HUP"
|
|
SIGILL Signal = "ILL"
|
|
SIGINT Signal = "INT"
|
|
SIGKILL Signal = "KILL"
|
|
SIGPIPE Signal = "PIPE"
|
|
SIGQUIT Signal = "QUIT"
|
|
SIGSEGV Signal = "SEGV"
|
|
SIGTERM Signal = "TERM"
|
|
SIGUSR1 Signal = "USR1"
|
|
SIGUSR2 Signal = "USR2"
|
|
)
|
|
|
|
// DefaultHandler is the default Handler used by Serve.
|
|
var DefaultHandler Handler
|
|
|
|
// Option is a functional option handler for Server.
|
|
type Option func(*Server) error
|
|
|
|
// Handler is a callback for handling established SSH sessions.
|
|
type Handler func(Session)
|
|
|
|
// PublicKeyHandler is a callback for performing public key authentication.
|
|
type PublicKeyHandler func(ctx Context, key PublicKey) error
|
|
|
|
type NoClientAuthHandler func(ctx Context) error
|
|
|
|
type BannerHandler func(ctx Context) string
|
|
|
|
// PasswordHandler is a callback for performing password authentication.
|
|
type PasswordHandler func(ctx Context, password string) bool
|
|
|
|
// KeyboardInteractiveHandler is a callback for performing keyboard-interactive authentication.
|
|
type KeyboardInteractiveHandler func(ctx Context, challenger gossh.KeyboardInteractiveChallenge) bool
|
|
|
|
// PtyCallback is a hook for allowing PTY sessions.
|
|
type PtyCallback func(ctx Context, pty Pty) bool
|
|
|
|
// SessionRequestCallback is a callback for allowing or denying SSH sessions.
|
|
type SessionRequestCallback func(sess Session, requestType string) bool
|
|
|
|
// ConnCallback is a hook for new connections before handling.
|
|
// It allows wrapping for timeouts and limiting by returning
|
|
// the net.Conn that will be used as the underlying connection.
|
|
type ConnCallback func(ctx Context, conn net.Conn) net.Conn
|
|
|
|
// LocalPortForwardingCallback is a hook for allowing port forwarding
|
|
type LocalPortForwardingCallback func(ctx Context, destinationHost string, destinationPort uint32) bool
|
|
|
|
// ReversePortForwardingCallback is a hook for allowing reverse port forwarding
|
|
type ReversePortForwardingCallback func(ctx Context, bindHost string, bindPort uint32) bool
|
|
|
|
// ServerConfigCallback is a hook for creating custom default server configs
|
|
type ServerConfigCallback func(ctx Context) *gossh.ServerConfig
|
|
|
|
// ConnectionFailedCallback is a hook for reporting failed connections
|
|
// Please note: the net.Conn is likely to be closed at this point
|
|
type ConnectionFailedCallback func(conn net.Conn, err error)
|
|
|
|
// Window represents the size of a PTY window.
|
|
//
|
|
// See https://datatracker.ietf.org/doc/html/rfc4254#section-6.2
|
|
//
|
|
// Zero dimension parameters MUST be ignored. The character/row dimensions
|
|
// override the pixel dimensions (when nonzero). Pixel dimensions refer
|
|
// to the drawable area of the window.
|
|
type Window struct {
|
|
// Width is the number of columns.
|
|
// It overrides WidthPixels.
|
|
Width int
|
|
// Height is the number of rows.
|
|
// It overrides HeightPixels.
|
|
Height int
|
|
|
|
// WidthPixels is the drawable width of the window, in pixels.
|
|
WidthPixels int
|
|
// HeightPixels is the drawable height of the window, in pixels.
|
|
HeightPixels int
|
|
}
|
|
|
|
// Pty represents a PTY request and configuration.
|
|
type Pty struct {
|
|
// Term is the TERM environment variable value.
|
|
Term string
|
|
|
|
// Window is the Window sent as part of the pty-req.
|
|
Window Window
|
|
|
|
// Modes represent a mapping of Terminal Mode opcode to value as it was
|
|
// requested by the client as part of the pty-req. These are outlined as
|
|
// part of https://datatracker.ietf.org/doc/html/rfc4254#section-8.
|
|
//
|
|
// The opcodes are defined as constants in github.com/tailscale/golang-x-crypto/ssh (VINTR,VQUIT,etc.).
|
|
// Boolean opcodes have values 0 or 1.
|
|
Modes gossh.TerminalModes
|
|
}
|
|
|
|
// Serve accepts incoming SSH connections on the listener l, creating a new
|
|
// connection goroutine for each. The connection goroutines read requests and
|
|
// then calls handler to handle sessions. Handler is typically nil, in which
|
|
// case the DefaultHandler is used.
|
|
func Serve(l net.Listener, handler Handler, options ...Option) error {
|
|
srv := &Server{Handler: handler}
|
|
for _, option := range options {
|
|
if err := srv.SetOption(option); err != nil {
|
|
return err
|
|
}
|
|
}
|
|
return srv.Serve(l)
|
|
}
|
|
|
|
// ListenAndServe listens on the TCP network address addr and then calls Serve
|
|
// with handler to handle sessions on incoming connections. Handler is typically
|
|
// nil, in which case the DefaultHandler is used.
|
|
func ListenAndServe(addr string, handler Handler, options ...Option) error {
|
|
srv := &Server{Addr: addr, Handler: handler}
|
|
for _, option := range options {
|
|
if err := srv.SetOption(option); err != nil {
|
|
return err
|
|
}
|
|
}
|
|
return srv.ListenAndServe()
|
|
}
|
|
|
|
// Handle registers the handler as the DefaultHandler.
|
|
func Handle(handler Handler) {
|
|
DefaultHandler = handler
|
|
}
|
|
|
|
// KeysEqual is constant time compare of the keys to avoid timing attacks.
|
|
func KeysEqual(ak, bk PublicKey) bool {
|
|
|
|
//avoid panic if one of the keys is nil, return false instead
|
|
if ak == nil || bk == nil {
|
|
return false
|
|
}
|
|
|
|
a := ak.Marshal()
|
|
b := bk.Marshal()
|
|
return (len(a) == len(b) && subtle.ConstantTimeCompare(a, b) == 1)
|
|
}
|