From 23474c19dc152d730bb554040a92d0b5a8ec59e9 Mon Sep 17 00:00:00 2001
From: bdnugget <bdbosman@gmail.com>
Date: Wed, 15 Jan 2025 10:51:43 +0100
Subject: [PATCH] Try to handle tcp fragmentation

---
 main.go | 59 +++++++++++++++++++++++++++++++++++++++------------------
 1 file changed, 41 insertions(+), 18 deletions(-)

diff --git a/main.go b/main.go
index 1159913..bb4ce58 100644
--- a/main.go
+++ b/main.go
@@ -1,7 +1,10 @@
 package main
 
 import (
+	"bufio"
+	"encoding/binary"
 	"fmt"
+	"io"
 	"log"
 	"net"
 	"sync"
@@ -76,22 +79,29 @@ func handleConnection(conn net.Conn) {
 		PlayerId:    int32(playerID),
 		CurrentTick: 0,
 	}
-	data, err := proto.Marshal(serverMsg)
-	if err != nil {
-		log.Printf("Failed to marshal ServerMessage for player %d: %v", playerID, err)
-		return
-	}
-	if _, err := conn.Write(data); err != nil {
+	if err := writeMessage(conn, serverMsg); err != nil {
 		log.Printf("Failed to send player ID to player %d: %v", playerID, err)
 		return
 	}
 
 	// Listen for incoming actions from this player
-	buf := make([]byte, 4096)
+	reader := bufio.NewReader(conn)
 	for {
-		n, err := conn.Read(buf)
-		if err != nil {
-			log.Printf("Error reading from player %d: %v", playerID, err)
+		// Read message length
+		lengthBuf := make([]byte, 4)
+		if _, err := io.ReadFull(reader, lengthBuf); err != nil {
+			log.Printf("Error reading message length from player %d: %v", playerID, err)
+			delete(players, playerID)
+			delete(playerConns, playerID)
+			delete(actionQueue, playerID)
+			return
+		}
+		messageLength := binary.BigEndian.Uint32(lengthBuf)
+
+		// Read message body
+		messageBuf := make([]byte, messageLength)
+		if _, err := io.ReadFull(reader, messageBuf); err != nil {
+			log.Printf("Error reading message from player %d: %v", playerID, err)
 			delete(players, playerID)
 			delete(playerConns, playerID)
 			delete(actionQueue, playerID)
@@ -99,7 +109,7 @@ func handleConnection(conn net.Conn) {
 		}
 
 		batch := &pb.ActionBatch{}
-		if err := proto.Unmarshal(buf[:n], batch); err != nil {
+		if err := proto.Unmarshal(messageBuf, batch); err != nil {
 			log.Printf("Failed to unmarshal action batch for player %d: %v", playerID, err)
 			continue
 		}
@@ -173,16 +183,29 @@ func processActions() {
 	state.ChatMessages = chatHistory[max(0, len(chatHistory)-5):] // Only send last 5 messages
 	chatMutex.RUnlock()
 
-	data, err := proto.Marshal(state)
-	if err != nil {
-		log.Printf("Failed to marshal game state: %v", err)
-		return
-	}
-
 	// Send to each connected player
 	for _, conn := range playerConns {
-		if _, err := conn.Write(data); err != nil {
+		if err := writeMessage(conn, state); err != nil {
 			log.Printf("Failed to send update: %v", err)
 		}
 	}
 }
+
+// Helper function to write length-prefixed messages
+func writeMessage(conn net.Conn, msg proto.Message) error {
+	data, err := proto.Marshal(msg)
+	if err != nil {
+		return err
+	}
+
+	// Write length prefix
+	lengthBuf := make([]byte, 4)
+	binary.BigEndian.PutUint32(lengthBuf, uint32(len(data)))
+	if _, err := conn.Write(lengthBuf); err != nil {
+		return err
+	}
+
+	// Write message body
+	_, err = conn.Write(data)
+	return err
+}