mirror of https://gogs.blitter.com/RLabs/xs
184 lines
4.4 KiB
Go
184 lines
4.4 KiB
Go
package main
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import (
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"flag"
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"fmt"
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"io"
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"io/ioutil"
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"log"
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"os"
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"os/user"
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"strings"
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"sync"
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hkex "blitter.com/hkexsh"
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isatty "github.com/mattn/go-isatty"
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)
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type cmdSpec struct {
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op []byte
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who []byte
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cmd []byte
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authCookie []byte
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status int
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}
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// Demo of a simple client that dials up to a simple test server to
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// send data.
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//
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// While conforming to the basic net.Conn interface HKex.Conn has extra
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// capabilities designed to allow apps to define connection options,
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// encryption/hmac settings and operations across the encrypted channel.
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//
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// Initial setup is the same as using plain net.Dial(), but one may
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// specify extra extension tags (strings) to set the cipher and hmac
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// setting desired; as well as the intended operation mode for the
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// connection (app-specific, passed through to the server to use or
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// ignore at its discretion).
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func main() {
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var wg sync.WaitGroup
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var dbg bool
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var cAlg string
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var hAlg string
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var server string
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var cmdStr string
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var altUser string
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var authCookie string
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isInteractive := false
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flag.StringVar(&cAlg, "c", "C_AES_256", "cipher [\"C_AES_256\" | \"C_TWOFISH_128\" | \"C_BLOWFISH_64\"]")
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flag.StringVar(&hAlg, "h", "H_SHA256", "hmac [\"H_SHA256\"]")
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flag.StringVar(&server, "s", "localhost:2000", "server hostname/address[:port]")
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flag.StringVar(&cmdStr, "x", "", "command to run (default empty - interactive shell)")
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flag.StringVar(&altUser, "u", "", "specify alternate user")
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flag.StringVar(&authCookie, "a", "", "auth cookie (MultiCheese3999(tm) 2FA cookie")
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flag.BoolVar(&dbg, "d", false, "debug logging")
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flag.Parse()
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if dbg {
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log.SetOutput(os.Stdout)
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} else {
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log.SetOutput(ioutil.Discard)
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}
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conn, err := hkex.Dial("tcp", server, cAlg, hAlg)
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if err != nil {
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fmt.Println("Err!")
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panic(err)
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}
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defer conn.Close()
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// From this point on, conn is a secure encrypted channel
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// Set stdin in raw mode if it's an interactive session
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// TODO: send flag to server side indicating this
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// affects shell command used
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if isatty.IsTerminal(os.Stdin.Fd()) {
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oldState, err := hkex.MakeRaw(int(os.Stdin.Fd()))
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if err != nil {
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panic(err)
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}
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defer func() { _ = hkex.Restore(int(os.Stdin.Fd()), oldState) }() // Best effort.
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} else {
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log.Println("NOT A TTY")
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}
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var uname string
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if len(altUser) == 0 {
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u, _ := user.Current()
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uname = u.Username
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} else {
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uname = altUser
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}
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var op []byte
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if len(cmdStr) == 0 {
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op = []byte{'s'}
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isInteractive = true
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} else if cmdStr == "-" {
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op = []byte{'c'}
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cmdStdin, err := ioutil.ReadAll(os.Stdin)
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if err != nil {
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panic(err)
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}
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cmdStr = strings.Trim(string(cmdStdin), "\r\n")
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} else {
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op = []byte{'c'}
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}
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if len(authCookie) == 0 {
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fmt.Printf("Gimme cookie:")
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ab, err := hkex.ReadPassword(int(os.Stdin.Fd()))
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fmt.Printf("\r\n")
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if err != nil {
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panic(err)
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}
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authCookie = string(ab)
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}
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rec := &cmdSpec{
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op: op,
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who: []byte(uname),
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cmd: []byte(cmdStr),
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authCookie: []byte(authCookie),
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status: 0}
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_, err = fmt.Fprintf(conn, "%d %d %d %d\n", len(rec.op), len(rec.who), len(rec.cmd), len(rec.authCookie))
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_, err = conn.Write(rec.op)
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_, err = conn.Write(rec.who)
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_, err = conn.Write(rec.cmd)
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_, err = conn.Write(rec.authCookie)
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//client reader (from server) goroutine
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wg.Add(1)
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go func() {
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// By deferring a call to wg.Done(),
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// each goroutine guarantees that it marks
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// its direction's stream as finished.
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//
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// Whichever direction's goroutine finishes first
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// will call wg.Done() once more, explicitly, to
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// hang up on the other side, so that this client
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// exits immediately on an EOF from either side.
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defer wg.Done()
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// io.Copy() expects EOF so this will
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// exit with inerr == nil
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_, inerr := io.Copy(os.Stdout, conn)
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if inerr != nil {
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if inerr.Error() != "EOF" {
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fmt.Println(inerr)
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os.Exit(1)
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}
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}
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if isInteractive {
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log.Println("[Got EOF]")
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wg.Done() // server hung up, close WaitGroup to exit client
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}
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}()
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if isInteractive {
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// client writer (to server) goroutine
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wg.Add(1)
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go func() {
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defer wg.Done()
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// io.Copy() expects EOF so this will
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// exit with outerr == nil
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_, outerr := io.Copy(conn, os.Stdin)
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if outerr != nil {
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if outerr.Error() != "EOF" {
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fmt.Println(outerr)
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os.Exit(2)
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}
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}
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log.Println("[Sent EOF]")
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wg.Done() // client hung up, close WaitGroup to exit client
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}()
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}
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// Wait until both stdin and stdout goroutines finish
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wg.Wait()
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}
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