151 lines
3.2 KiB
Go
151 lines
3.2 KiB
Go
//
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// Copyright (c) 2018, Přemysl Eric Janouch <p@janouch.name>
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//
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// Permission to use, copy, modify, and/or distribute this software for any
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// purpose with or without fee is hereby granted.
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//
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// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
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// SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
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// OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
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// CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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//
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// hnc is a netcat-alike that shuts down properly.
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package main
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import (
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"crypto/tls"
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"flag"
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"fmt"
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"io"
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"net"
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"os"
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)
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// #include <unistd.h>
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import "C"
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func isatty(fd uintptr) bool { return C.isatty(C.int(fd)) != 0 }
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func log(format string, args ...interface{}) {
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msg := fmt.Sprintf(format+"\n", args...)
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if isatty(os.Stderr.Fd()) {
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msg = "\x1b[0;1;31m" + msg + "\x1b[m"
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}
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os.Stderr.WriteString(msg)
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}
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var (
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flagTLS = flag.Bool("tls", false, "connect using TLS")
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flagCRLF = flag.Bool("crlf", false, "translate LF into CRLF")
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)
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// Network connection that can shut down the write end.
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type connCloseWriter interface {
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net.Conn
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CloseWrite() error
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}
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func dial(address string) (connCloseWriter, error) {
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if *flagTLS {
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return tls.Dial("tcp", address, &tls.Config{
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InsecureSkipVerify: true,
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})
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}
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transport, err := net.Dial("tcp", address)
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if err != nil {
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return nil, err
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}
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return transport.(connCloseWriter), nil
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}
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func expand(raw []byte) []byte {
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if !*flagCRLF {
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return raw
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}
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var res []byte
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for _, b := range raw {
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if b == '\n' {
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res = append(res, '\r')
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}
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res = append(res, b)
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}
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return res
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}
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// Asynchronously delivered result of io.Reader.
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type readResult struct {
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b []byte
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err error
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}
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func read(r io.Reader, ch chan<- readResult) {
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defer close(ch)
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for {
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var buf [8192]byte
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n, err := r.Read(buf[:])
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ch <- readResult{buf[:n], err}
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if err != nil {
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break
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}
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}
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}
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func main() {
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flag.Usage = func() {
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fmt.Fprintf(flag.CommandLine.Output(),
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"Usage: %s [OPTION]... HOST PORT\n"+
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"Connect to a remote host over TCP/IP.\n", os.Args[0])
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flag.PrintDefaults()
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}
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flag.Parse()
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if flag.NArg() != 2 {
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flag.Usage()
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os.Exit(2)
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}
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conn, err := dial(net.JoinHostPort(flag.Arg(0), flag.Arg(1)))
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if err != nil {
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log("dial: %s", err)
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os.Exit(1)
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}
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fromUser := make(chan readResult)
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go read(os.Stdin, fromUser)
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fromConn := make(chan readResult)
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go read(conn, fromConn)
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for fromUser != nil || fromConn != nil {
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select {
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case result := <-fromUser:
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if len(result.b) > 0 {
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if _, err := conn.Write(expand(result.b)); err != nil {
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log("remote: %s", err)
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}
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}
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if result.err != nil {
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log("stdin: %s", result.err)
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fromUser = nil
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if err := conn.CloseWrite(); err != nil {
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log("remote: %s", err)
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}
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}
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case result := <-fromConn:
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if len(result.b) > 0 {
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if _, err := os.Stdout.Write(result.b); err != nil {
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log("stdout: %s", err)
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}
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}
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if result.err != nil {
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log("remote: %s", result.err)
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fromConn = nil
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}
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}
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}
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}
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