Question

I am building a simple telnet connection daemon for communications between internal network applications, and I ran into an issue when reading the first line from BufferedReader.

This code snippet is not complete due to the fact there is a lot of other junk in there so I have stripped it down only to include the object creation and read from the steam.

in = new BufferedReader(new InputStreamReader(this.client.getInputStream()));
out = new PrintWriter(this.client.getOutputStream(), true);
String line;

while (true) {
    out.println(flag); // flag is just an integer               
    System.out.println(line);
    // Processing the line and updating 'flag' accordingly
}

Entering test into the telnet connection yielded  v? v  v? v' ²? v? ²?test in the console that was running the program. This does not happen to lines sent after the first one.

Is there a way to clear that garbage out before the user interfaces with it so it doesn’t get sent with the first line? or is this issue caused by my telnet client (and might be fixed when I write a client that interfaces with this)?

Answer 1

I strongly suspect it’s the telnet protocol negotiation. Ideally, you should handle it having read RFC 854 carefully.

Note that you shouldn’t just use InputStreamReader without specifying the character encoding – it’s very unlikely that the platform default encoding is the one you want.