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128 lines
4.0 KiB
128 lines
4.0 KiB
package ssh
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import (
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"crypto/subtle"
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"net"
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gossh "golang.org/x/crypto/ssh"
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)
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type Signal string
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// POSIX signals as listed in RFC 4254 Section 6.10.
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const (
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SIGABRT Signal = "ABRT"
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SIGALRM Signal = "ALRM"
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SIGFPE Signal = "FPE"
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SIGHUP Signal = "HUP"
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SIGILL Signal = "ILL"
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SIGINT Signal = "INT"
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SIGKILL Signal = "KILL"
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SIGPIPE Signal = "PIPE"
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SIGQUIT Signal = "QUIT"
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SIGSEGV Signal = "SEGV"
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SIGTERM Signal = "TERM"
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SIGUSR1 Signal = "USR1"
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SIGUSR2 Signal = "USR2"
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)
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// DefaultHandler is the default Handler used by Serve.
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var DefaultHandler Handler
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// Option is a functional option handler for Server.
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type Option func(*Server) error
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// Handler is a callback for handling established SSH sessions.
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type Handler func(Session)
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// PublicKeyHandler is a callback for performing public key authentication.
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type PublicKeyHandler func(ctx Context, key PublicKey) bool
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// PasswordHandler is a callback for performing password authentication.
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type PasswordHandler func(ctx Context, password string) bool
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// KeyboardInteractiveHandler is a callback for performing keyboard-interactive authentication.
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type KeyboardInteractiveHandler func(ctx Context, challenger gossh.KeyboardInteractiveChallenge) bool
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// PtyCallback is a hook for allowing PTY sessions.
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type PtyCallback func(ctx Context, pty Pty) bool
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// SessionRequestCallback is a callback for allowing or denying SSH sessions.
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type SessionRequestCallback func(sess Session, requestType string) bool
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// ConnCallback is a hook for new connections before handling.
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// It allows wrapping for timeouts and limiting by returning
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// the net.Conn that will be used as the underlying connection.
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type ConnCallback func(ctx Context, conn net.Conn) net.Conn
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// LocalPortForwardingCallback is a hook for allowing port forwarding
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type LocalPortForwardingCallback func(ctx Context, destinationHost string, destinationPort uint32) bool
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// ReversePortForwardingCallback is a hook for allowing reverse port forwarding
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type ReversePortForwardingCallback func(ctx Context, bindHost string, bindPort uint32) bool
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// ServerConfigCallback is a hook for creating custom default server configs
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type ServerConfigCallback func(ctx Context) *gossh.ServerConfig
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// ConnectionFailedCallback is a hook for reporting failed connections
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// Please note: the net.Conn is likely to be closed at this point
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type ConnectionFailedCallback func(conn net.Conn, err error)
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// Window represents the size of a PTY window.
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type Window struct {
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Width int
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Height int
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}
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// Pty represents a PTY request and configuration.
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type Pty struct {
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Term string
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Window Window
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// HELP WANTED: terminal modes!
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}
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// Serve accepts incoming SSH connections on the listener l, creating a new
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// connection goroutine for each. The connection goroutines read requests and
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// then calls handler to handle sessions. Handler is typically nil, in which
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// case the DefaultHandler is used.
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func Serve(l net.Listener, handler Handler, options ...Option) error {
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srv := &Server{Handler: handler}
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for _, option := range options {
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if err := srv.SetOption(option); err != nil {
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return err
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}
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}
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return srv.Serve(l)
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}
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// ListenAndServe listens on the TCP network address addr and then calls Serve
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// with handler to handle sessions on incoming connections. Handler is typically
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// nil, in which case the DefaultHandler is used.
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func ListenAndServe(addr string, handler Handler, options ...Option) error {
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srv := &Server{Addr: addr, Handler: handler}
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for _, option := range options {
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if err := srv.SetOption(option); err != nil {
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return err
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}
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}
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return srv.ListenAndServe()
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}
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// Handle registers the handler as the DefaultHandler.
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func Handle(handler Handler) {
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DefaultHandler = handler
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}
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// KeysEqual is constant time compare of the keys to avoid timing attacks.
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func KeysEqual(ak, bk PublicKey) bool {
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//avoid panic if one of the keys is nil, return false instead
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if ak == nil || bk == nil {
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return false
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}
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a := ak.Marshal()
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b := bk.Marshal()
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return (len(a) == len(b) && subtle.ConstantTimeCompare(a, b) == 1)
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}
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