Remove network dependency from protocol parser

Following the sans io principle
https://sans-io.readthedocs.io/

messages7/ctrl_keep_alive.go

@@ -0,0 +1,29 @@
+package messages7
+
+import (
+	"github.com/teeworlds-go/teeworlds/network7"
+)
+
+type CtrlKeepAlive struct {
+}
+
+func (msg CtrlKeepAlive) MsgId() int {
+	return network7.MsgCtrlKeepAlive
+}
+
+func (msg CtrlKeepAlive) MsgType() network7.MsgType {
+	return network7.TypeControl
+}
+
+func (msg CtrlKeepAlive) System() bool {
+	return false
+}
+
+func (msg CtrlKeepAlive) Vital() bool {
+	return false
+}
+
+func (msg CtrlKeepAlive) Pack() []byte {
+	return []byte{network7.MsgCtrlKeepAlive}
+}
+

protocol7/connection.go

@@ -3,9 +3,7 @@ package protocol7
 import (
 	"bytes"
 	"fmt"
-	"net"
 	"os"
-	"slices"
 
 	"github.com/teeworlds-go/huffman"
 	"github.com/teeworlds-go/teeworlds/chunk7"
@@ -21,7 +19,6 @@ type Player struct {
 type Connection struct {
 	ClientToken [4]byte
 	ServerToken [4]byte
-	Conn        net.Conn
 
 	// The amount of vital chunks received
 	Ack int
@@ -64,27 +61,6 @@ func (connection *Connection) CtrlToken() *Packet {
 	return response
 }
 
-func (c *Connection) SendCtrlMsg(data []byte) {
-	header := PacketHeader{
-		Flags: PacketFlags{
-			Connless:    false,
-			Compression: false,
-			Resend:      false,
-			Control:     true,
-		},
-		Ack:       c.Ack,
-		NumChunks: 0,
-		Token:     c.ServerToken,
-	}
-
-	packet := slices.Concat(header.Pack(), data)
-	c.Conn.Write(packet)
-}
-
-func (c *Connection) SendKeepAlive() {
-	c.SendCtrlMsg([]byte{byte(network7.MsgCtrlKeepAlive)})
-}
-
 func (client *Connection) MsgStartInfo() messages7.ClStartInfo {
 	return messages7.ClStartInfo{
 		Name:                  "gopher",
@@ -129,7 +105,7 @@ func (connection *Connection) OnSystemMsg(msg int, chunk chunk7.Chunk, u *packer
 	} else if msg == network7.MsgSysSnapSingle {
 		// tick := u.GetInt()
 		// fmt.Printf("got snap single tick=%d\n", tick)
-		connection.SendKeepAlive()
+		response.Messages = append(response.Messages, messages7.CtrlKeepAlive{})
 	} else {
 		fmt.Printf("unknown system message id=%d data=%x\n", msg, chunk.Data)
 	}

teeworlds.go

@@ -53,12 +53,11 @@ func main() {
 	client := &protocol7.Connection{
 		ClientToken: [4]byte{0x01, 0x02, 0x03, 0x04},
 		ServerToken: [4]byte{0xff, 0xff, 0xff, 0xff},
-		Conn:        conn,
 		Ack:         0,
 		Players:     make([]protocol7.Player, network7.MaxClients),
 	}
 
-	go readNetwork(ch, client.Conn)
+	go readNetwork(ch, conn)
 
 	packet := client.CtrlToken()
 	conn.Write(packet.Pack(client))