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tailscale/cmd/tailscale/cli/ssh_unix.go

50 lines
1.1 KiB
Go

// Copyright (c) Tailscale Inc & AUTHORS
// SPDX-License-Identifier: BSD-3-Clause
//go:build !js && !windows
package cli
import (
"bytes"
"os"
"path/filepath"
"runtime"
"strconv"
"golang.org/x/sys/unix"
)
func init() {
getSSHClientEnvVar = func() string {
if os.Getenv("SUDO_USER") == "" {
// No sudo, just check the env.
return os.Getenv("SSH_CLIENT")
}
if runtime.GOOS != "linux" {
// TODO(maisem): implement this for other platforms. It's not clear
// if there is a way to get the environment for a given process on
// darwin and bsd.
return ""
}
// SID is the session ID of the user's login session.
// It is also the process ID of the original shell that the user logged in with.
// We only need to check the environment of that process.
sid, err := unix.Getsid(os.Getpid())
if err != nil {
return ""
}
b, err := os.ReadFile(filepath.Join("/proc", strconv.Itoa(sid), "environ"))
if err != nil {
return ""
}
prefix := []byte("SSH_CLIENT=")
for _, env := range bytes.Split(b, []byte{0}) {
if bytes.HasPrefix(env, prefix) {
return string(env[len(prefix):])
}
}
return ""
}
}