CODEWITHSUNDEEP
kotlinwebsockettcprfc6455
JohnyTheCarrot
JohnyTheCarrot

Reputation: 103

WebSocket handshake response missing HTTP status line

Due to an interest in the subject, I've decided to have a go at making a WebSocket client library for Kotlin using TCP.

So, I'm reading RFC6455 and it mentions that in the handshake, the server response should have a HTTP status line. Cool, I make my request:

GET / HTTP/1.1
Host: echo.websocket.org:80
Upgrade: websocket
Connection: Upgrade
Accept: */*
Sec-WebSocket-Version: 13
Sec-WebSocket-Key: Dg8CY18ZTGbAkIzNhpO3mA==

and the server replies with

Connection: Upgrade
Sec-WebSocket-Accept: akyZ/0pr8WyuXVfejRWVAUGSW3k=
Upgrade: websocket

As you can see, no HTTP status line. Did I miss something in RFC6455, is my code dumb?

code (PayloadFactory.kt):

fun createSecWebSocketKey(): String? {
    val bytes = ByteArray(16)
    SecureRandom.getInstanceStrong().nextBytes(bytes)
    return String(Base64.getEncoder().encode(bytes)!!)
}

fun createOpeningHandshake(host: String, path: String = "/", port: Int = 80, protocolVersion: Int = 13): String
{
    // I'm aware path isn't used yet, that's something I plan to implement but haven't yet.
    var handshake = ""
    handshake += "GET / HTTP/1.1\r\n"
    handshake += "Host: $host:$port\r\n"
    handshake += "Upgrade: websocket\r\n"
    handshake += "Connection: Upgrade\r\n"
    handshake += "Accept: */*\r\n"
    handshake += "Sec-WebSocket-Version: $protocolVersion\r\n"
    handshake += "Sec-WebSocket-Key: ${createSecWebSocketKey()}\r\n\r\n"
    return handshake
}

code (WebSocket.kt):

class WebSocket(protocol: String, host: String, port: Int = 80, protocolVersion: Int = 13) {
    private val client: Socket = Socket(host, port)
    private val globallyUniqueIdentifier = "258EAFA5-E914-47DA-95CA-C5AB0DC85B11"

    init {
        val handshake = createOpeningHandshake(host, protocolVersion = protocolVersion)
        println("============CLIENT HANDSHAKE============")
        println(handshake)
        client.getOutputStream().write(handshake.toByteArray())
        println("============SERVER RESPONSE=============")
        val input = BufferedReader(InputStreamReader(client.getInputStream()))
        while (true)
        {
            if (input.readLine() != null) {
                val line = input.readLine()
                println(line)
            }
        }
    }
}

to run: WebSocket("ws", "echo.websocket.org", 80)

Upvotes: -1

Views: 276

Answers (1)

JohnyTheCarrot
JohnyTheCarrot

Reputation: 103

SOLVED

I was not storing the result of readLine() in a variable, causing me to essentially discard every odd line in the response. Thanks to user207421 for pointing it out!

Upvotes: 0

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