Implemented first demo of tool for connection to quassel cores

.gitignore

+*.iml
+/.idea/*
+!/.idea/copyright/
+.DS_Store
\ No newline at end of file

main.go

+package main
+
+import (
+	"bufio"
+	"crypto/tls"
+	"encoding/binary"
+	"fmt"
+	"net"
+)
+
+const PROTOCOL_MAGIC uint32 = 0x42b33f00
+
+const PROTOCOL_FEATURE_TLS uint8 = 0x01
+const PROTOCOL_FEATURE_COMPRESSION uint8 = 0x02
+
+const PROTOCOL_LEGACY uint32 = 0x01
+const PROTOCOL_DATASTREAM uint32 = 0x02
+
+type connection struct {
+	hostname   string
+	socket     net.Conn
+	tlsSocket  *tls.Conn
+	readWriter *bufio.ReadWriter
+	buffer     []byte
+}
+
+func makeConnection(address string, port int) connection {
+	socket, err := net.Dial("tcp", fmt.Sprintf("%s:%d", address, port))
+	if err != nil {
+		panic(err.Error())
+	}
+
+	return connection{
+		hostname: address,
+		socket:   socket,
+		readWriter: bufio.NewReadWriter(
+			bufio.NewReader(socket),
+			bufio.NewWriter(socket),
+		),
+		buffer: make([]byte, 4),
+	}
+}
+
+func (c *connection) write(data uint32) {
+	binary.BigEndian.PutUint32(c.buffer, data)
+	_, err := c.readWriter.Write(c.buffer)
+	if err != nil {
+		panic(err.Error())
+	}
+}
+
+func (c *connection) read(len int) []byte {
+	buffer := make([]byte, len)
+	_, err := c.readWriter.Read(buffer)
+	if err != nil {
+		panic(err.Error())
+	}
+	return buffer
+}
+
+func (c *connection) flush() {
+	err := c.readWriter.Flush()
+	if err != nil {
+		panic(err.Error())
+	}
+}
+
+func (c *connection) withTLS(verify bool) {
+	config := &tls.Config{
+		ServerName:         c.hostname,
+		InsecureSkipVerify: !verify,
+	}
+	c.tlsSocket = tls.Client(c.socket, config)
+	c.readWriter = bufio.NewReadWriter(
+		bufio.NewReader(c.tlsSocket),
+		bufio.NewWriter(c.tlsSocket),
+	)
+	err := c.tlsSocket.Handshake()
+	if err != nil {
+		panic(err.Error())
+	}
+}
+
+func (c *connection) tlsState() *tls.ConnectionState {
+	if c.tlsSocket != nil {
+		state := c.tlsSocket.ConnectionState()
+		return &state
+	} else {
+		return nil
+	}
+}
+
+func (c *connection) close() {
+	_ = c.readWriter.Flush()
+	_ = c.tlsSocket.Close()
+	_ = c.socket.Close()
+}
+
+type protocolInfo struct {
+	flagTLS         bool
+	flagCompression bool
+	data            uint16
+	version         uint8
+}
+
+func parseProtocolInfo(data []byte) protocolInfo {
+	rawFeatures := data[0]
+	rawData := data[1:3]
+	rawVersion := data[3]
+
+	return protocolInfo{
+		rawFeatures&PROTOCOL_FEATURE_TLS != 0,
+		rawFeatures&PROTOCOL_FEATURE_COMPRESSION != 0,
+		binary.BigEndian.Uint16(rawData),
+		rawVersion,
+	}
+}
+
+func main() {
+	conn := makeConnection("kuschku.de", 4242)
+	conn.write(PROTOCOL_MAGIC | uint32(PROTOCOL_FEATURE_TLS))
+	supportedProtocols := []uint32{
+		PROTOCOL_DATASTREAM,
+	}
+	for _, protocol := range supportedProtocols {
+		conn.write(protocol)
+	}
+	conn.write(1 << 31)
+	conn.flush()
+	protocolInfo := parseProtocolInfo(conn.read(4))
+	println("Read Protocol Info")
+	if protocolInfo.flagTLS {
+		conn.withTLS(false)
+	}
+	if state := conn.tlsState(); state != nil {
+		for _, cert := range state.PeerCertificates {
+			println(cert.NotAfter.String())
+		}
+	}
+	conn.close()
+}