better readme

this fixes a race condition where if 2 goroutines try to send a packet at the same time, they could end up being
malformed due to the 2 separate calls to peer.conn.Write().

instead of writing the packet size to peer.conn.Write() directly, we make space in buf for the packet size,
and patch it in place. this lets us get away with only having 1 call to peer.conn.Write() which will ensure that
the full packet is written properly and be goroutine safe :3

README.md

@@ -1,10 +1,10 @@
 # gopenfusion
 
-A toy implementation of the [Fusionfall Packet Protocol](https://openpunk.com/pages/fusionfall-openfusion/) written in Go.
+A toy implementation of the [Fusionfall Packet Protocol](https://openpunk.com/pages/fusionfall-openfusion/) and accompanying services, written in Go.
 
 ## Landwalker demo
 
-An implementation of a landwalker server is located in `login/` && `shard/`. This includes a functional login server and a dummy shard (supporting the minimum amount of packets necessary). The DB implementation in `core/db/` matches the OpenFusion 1.4 SQLite tables, which the login server uses. There's no support for NPCs nor other players, and is liable to softlock the client.
+An implementation of a landwalker server is located in `login/` && `shard/`. This includes a functional login server and a dummy shard (supporting the minimum amount of packets necessary). There is minimal support for NPCs, and minimal support for player interaction (chat & player movement being mostly it).
 
 Startup the environment using
 
@@ -13,6 +13,8 @@ $ chmod +x ./build.sh && ./build.sh
 $ docker compose up
 ```
 
+The environment consists of a shard service, login service, redis && postgres containers. redis is used to pass login metadata between the login and shard services, while postgres is just used to store player accounts and characters.
+
 login server is hosted at `127.0.0.1:23000`, just join from your [favorite client](https://github.com/OpenFusionProject/OpenFusion/releases/latest)
 
 ## Generating structures

cmd/main.go

@@ -7,8 +7,8 @@ import (
 	"os"
 
 	"github.com/CPunch/gopenfusion/config"
-	"github.com/CPunch/gopenfusion/core/db"
+	"github.com/CPunch/gopenfusion/internal/db"
-	"github.com/CPunch/gopenfusion/core/redis"
+	"github.com/CPunch/gopenfusion/internal/redis"
 
 	"github.com/google/subcommands"
 )

internal/db/account.go

@@ -6,7 +6,7 @@ import (
 
 	"golang.org/x/crypto/bcrypt"
 
-	"github.com/CPunch/gopenfusion/core/protocol"
+	"github.com/CPunch/gopenfusion/internal/protocol"
 	"github.com/georgysavva/scany/v2/sqlscan"
 )
 

internal/db/inventory.go

@@ -3,7 +3,7 @@ package db
 import (
 	"database/sql"
 
-	"github.com/CPunch/gopenfusion/core/protocol"
+	"github.com/CPunch/gopenfusion/internal/protocol"
 )
 
 type Inventory struct {

internal/db/players.go

@@ -4,8 +4,8 @@ import (
 	"database/sql"
 
 	"github.com/CPunch/gopenfusion/config"
-	"github.com/CPunch/gopenfusion/core/entity"
+	"github.com/CPunch/gopenfusion/internal/entity"
-	"github.com/CPunch/gopenfusion/core/protocol"
+	"github.com/CPunch/gopenfusion/internal/protocol"
 	"github.com/blockloop/scan"
 )
 

internal/entity/entity.go

@@ -1,6 +1,6 @@
 package entity
 
-import "github.com/CPunch/gopenfusion/core/protocol"
+import "github.com/CPunch/gopenfusion/internal/protocol"
 
 type EntityKind int
 

internal/entity/npc.go

@@ -3,7 +3,7 @@ package entity
 import (
 	"sync/atomic"
 
-	"github.com/CPunch/gopenfusion/core/protocol"
+	"github.com/CPunch/gopenfusion/internal/protocol"
 )
 
 type NPC struct {

internal/entity/player.go

@@ -2,7 +2,7 @@ package entity
 
 import (
 	"github.com/CPunch/gopenfusion/config"
-	"github.com/CPunch/gopenfusion/core/protocol"
+	"github.com/CPunch/gopenfusion/internal/protocol"
 )
 
 type Player struct {

internal/protocol/cnpeer.go

@@ -8,7 +8,7 @@ import (
 	"net"
 	"time"
 
-	"github.com/CPunch/gopenfusion/core/protocol/pool"
+	"github.com/CPunch/gopenfusion/internal/protocol/pool"
 )
 
 const (
@@ -51,6 +51,9 @@ func (peer *CNPeer) Send(typeID uint32, data ...interface{}) error {
 	buf := pool.Get()
 	defer pool.Put(buf)
 
+	// allocate space for packet size
+	buf.Write(make([]byte, 4))
+
 	// body start
 	pkt := NewPacket(buf)
 
@@ -66,25 +69,22 @@ func (peer *CNPeer) Send(typeID uint32, data ...interface{}) error {
 		}
 	}
 
+	// prepend the packet size
+	binary.LittleEndian.PutUint32(buf.Bytes()[:4], uint32(buf.Len()-4))
+
 	// encrypt body
 	switch peer.whichKey {
 	case USE_E:
-		EncryptData(buf.Bytes(), peer.E_key)
+		EncryptData(buf.Bytes()[4:], peer.E_key)
 	case USE_FE:
-		EncryptData(buf.Bytes(), peer.FE_key)
+		EncryptData(buf.Bytes()[4:], peer.FE_key)
 	}
 
-	// write packet size
+	// send full packet
-	if err := binary.Write(peer.conn, binary.LittleEndian, uint32(buf.Len())); err != nil {
+	log.Printf("Sending %#v, sizeof: %d, buffer: %v", data, buf.Len(), buf.Bytes())
-		return err
-	}
-
-	// write packet body
-	log.Printf("Sending %#v, sizeof: %d", data, buf.Len())
 	if _, err := peer.conn.Write(buf.Bytes()); err != nil {
-		return fmt.Errorf("[FATAL] failed to write packet body! %v", err)
+		return fmt.Errorf("failed to write packet body! %v", err)
 	}
-
 	return nil
 }
 

internal/protocol/packet.go

@@ -31,7 +31,7 @@ func (pkt Packet) encodeStructField(field reflect.StructField, value reflect.Val
 	case reflect.String: // all strings in fusionfall packets are encoded as utf16, we'll need to encode it
 		sz, err := strconv.Atoi(field.Tag.Get("size"))
 		if err != nil {
-			return fmt.Errorf("Failed to grab string 'size' tag!!")
+			return fmt.Errorf("failed to grab string 'size' tag")
 		}
 
 		buf16 := utf16.Encode([]rune(value.String()))
@@ -100,7 +100,7 @@ func (pkt Packet) decodeStructField(field reflect.StructField, value reflect.Val
 	case reflect.String: // all strings in fusionfall packets are encoded as utf16, we'll need to decode it
 		sz, err := strconv.Atoi(field.Tag.Get("size"))
 		if err != nil {
-			return fmt.Errorf("Failed to grab string 'size' tag!!")
+			return fmt.Errorf("failed to grab string 'size' tag")
 		}
 
 		buf16 := make([]uint16, sz)

login/login.go

@@ -7,9 +7,9 @@ import (
 	"math/rand"
 
 	"github.com/CPunch/gopenfusion/config"
-	"github.com/CPunch/gopenfusion/core/db"
+	"github.com/CPunch/gopenfusion/internal/db"
-	"github.com/CPunch/gopenfusion/core/protocol"
+	"github.com/CPunch/gopenfusion/internal/protocol"
-	"github.com/CPunch/gopenfusion/core/redis"
+	"github.com/CPunch/gopenfusion/internal/redis"
 )
 
 const (
@@ -76,7 +76,7 @@ func (server *LoginServer) Login(peer *protocol.CNPeer, pkt protocol.Packet) err
 	// client is resending a login packet??
 	if peer.AccountID != -1 {
 		SendError(LOGIN_ERROR)
-		return fmt.Errorf("Out of order P_CL2LS_REQ_LOGIN!")
+		return fmt.Errorf("out of order P_CL2LS_REQ_LOGIN")
 	}
 
 	// attempt login
@@ -155,7 +155,7 @@ func (server *LoginServer) SaveCharacterName(peer *protocol.CNPeer, pkt protocol
 
 	if peer.AccountID == -1 {
 		peer.Send(protocol.P_LS2CL_REP_SAVE_CHAR_NAME_FAIL, protocol.SP_LS2CL_REP_SAVE_CHAR_NAME_FAIL{})
-		return fmt.Errorf("Out of order P_LS2CL_REP_SAVE_CHAR_NAME_FAIL!")
+		return fmt.Errorf("out of order P_LS2CL_REP_SAVE_CHAR_NAME_FAIL")
 	}
 
 	// TODO: sanity check SzFirstName && SzLastName
@@ -260,7 +260,7 @@ func (server *LoginServer) ShardSelect(peer *protocol.CNPeer, pkt protocol.Packe
 	shards := server.redisHndlr.GetShards()
 	if len(shards) == 0 {
 		SendFail(peer)
-		return fmt.Errorf("LoginServer has found no linked shards!")
+		return fmt.Errorf("loginServer has found no linked shards")
 	}
 
 	key, err := protocol.GenSerialKey()

login/loginserver.go

@@ -7,10 +7,10 @@ import (
 	"sync"
 
 	"github.com/CPunch/gopenfusion/config"
-	"github.com/CPunch/gopenfusion/core/db"
+	"github.com/CPunch/gopenfusion/internal/db"
-	"github.com/CPunch/gopenfusion/core/protocol"
+	"github.com/CPunch/gopenfusion/internal/protocol"
-	"github.com/CPunch/gopenfusion/core/protocol/pool"
+	"github.com/CPunch/gopenfusion/internal/protocol/pool"
-	"github.com/CPunch/gopenfusion/core/redis"
+	"github.com/CPunch/gopenfusion/internal/redis"
 )
 
 type PacketHandler func(peer *protocol.CNPeer, pkt protocol.Packet) error
@@ -81,20 +81,18 @@ func (server *LoginServer) Start() {
 }
 
 func (server *LoginServer) handleEvents() {
-	for {
+	for event := range server.eRecv {
-		select {
+		switch event.Type {
-		case event := <-server.eRecv:
+		case protocol.EVENT_CLIENT_DISCONNECT:
-			switch event.Type {
+			server.disconnect(event.Peer)
-			case protocol.EVENT_CLIENT_DISCONNECT:
+		case protocol.EVENT_CLIENT_PACKET:
-				server.disconnect(event.Peer)
+			if err := server.handlePacket(event.Peer, event.PktID, protocol.NewPacket(event.Pkt)); err != nil {
-			case protocol.EVENT_CLIENT_PACKET:
+				log.Printf("Error handling packet: %v", err)
-				defer pool.Put(event.Pkt)
+				event.Peer.Kill()
-
-				if err := server.handlePacket(event.Peer, event.PktID, protocol.NewPacket(event.Pkt)); err != nil {
-					log.Printf("Error handling packet: %v", err)
-					event.Peer.Kill()
-				}
 			}
+
+			// the packet is given to us by the event, so we'll need to make sure to return it to the pool
+			pool.Put(event.Pkt)
 		}
 	}
 }

shard/chat.go

@@ -1,6 +1,6 @@
 package shard
 
-import "github.com/CPunch/gopenfusion/core/protocol"
+import "github.com/CPunch/gopenfusion/internal/protocol"
 
 func (server *ShardServer) freeChat(peer *protocol.CNPeer, pkt protocol.Packet) error {
 	var chat protocol.SP_CL2FE_REQ_SEND_FREECHAT_MESSAGE

shard/entitymanager.go

@@ -1,7 +1,7 @@
 package shard
 
 import (
-	"github.com/CPunch/gopenfusion/core/entity"
+	"github.com/CPunch/gopenfusion/internal/entity"
 )
 
 func (server *ShardServer) addEntity(e entity.Entity) {

shard/join.go

@@ -4,16 +4,16 @@ import (
 	"fmt"
 	"log"
 
-	"github.com/CPunch/gopenfusion/core/entity"
+	"github.com/CPunch/gopenfusion/internal/entity"
-	"github.com/CPunch/gopenfusion/core/protocol"
+	"github.com/CPunch/gopenfusion/internal/protocol"
-	"github.com/CPunch/gopenfusion/core/redis"
+	"github.com/CPunch/gopenfusion/internal/redis"
 )
 
 func (server *ShardServer) attachPlayer(peer *protocol.CNPeer, meta redis.LoginMetadata) (*entity.Player, error) {
 	// resending a shard enter packet?
-	old, err := server.getPlayer(peer)
+	old, _ := server.getPlayer(peer)
 	if old != nil {
-		return nil, fmt.Errorf("resent enter packet!")
+		return nil, fmt.Errorf("resent enter packet")
 	}
 
 	// attach player

shard/movement.go

@@ -1,8 +1,8 @@
 package shard
 
 import (
-	"github.com/CPunch/gopenfusion/core/entity"
+	"github.com/CPunch/gopenfusion/internal/entity"
-	"github.com/CPunch/gopenfusion/core/protocol"
+	"github.com/CPunch/gopenfusion/internal/protocol"
 )
 
 func (server *ShardServer) updatePlayerPosition(plr *entity.Player, X, Y, Z, Angle int) {

shard/npcloader.go

@@ -6,7 +6,7 @@ import (
 	"os"
 
 	"github.com/CPunch/gopenfusion/config"
-	"github.com/CPunch/gopenfusion/core/entity"
+	"github.com/CPunch/gopenfusion/internal/entity"
 )
 
 type NPCData struct {

shard/shardserver.go

@@ -7,17 +7,15 @@ import (
 	"sync"
 
 	"github.com/CPunch/gopenfusion/config"
-	"github.com/CPunch/gopenfusion/core/db"
+	"github.com/CPunch/gopenfusion/internal/db"
-	"github.com/CPunch/gopenfusion/core/entity"
+	"github.com/CPunch/gopenfusion/internal/entity"
-	"github.com/CPunch/gopenfusion/core/protocol"
+	"github.com/CPunch/gopenfusion/internal/protocol"
-	"github.com/CPunch/gopenfusion/core/protocol/pool"
+	"github.com/CPunch/gopenfusion/internal/protocol/pool"
-	"github.com/CPunch/gopenfusion/core/redis"
+	"github.com/CPunch/gopenfusion/internal/redis"
 )
 
 type PacketHandler func(peer *protocol.CNPeer, pkt protocol.Packet) error
 
-func stubbedPacket(_ *protocol.CNPeer, _ protocol.Packet) error { /* stubbed */ return nil }
-
 type ShardServer struct {
 	listener       net.Listener
 	port           int
@@ -67,18 +65,17 @@ func NewShardServer(dbHndlr *db.DBHandler, redisHndlr *redis.RedisHandler, port
 }
 
 func (server *ShardServer) handleEvents() {
-	for {
+	for event := range server.eRecv {
-		select {
+		switch event.Type {
-		case event := <-server.eRecv:
+		case protocol.EVENT_CLIENT_DISCONNECT:
-			switch event.Type {
+			server.disconnect(event.Peer)
-			case protocol.EVENT_CLIENT_DISCONNECT:
+		case protocol.EVENT_CLIENT_PACKET:
-				server.disconnect(event.Peer)
+			if err := server.handlePacket(event.Peer, event.PktID, protocol.NewPacket(event.Pkt)); err != nil {
-			case protocol.EVENT_CLIENT_PACKET:
+				event.Peer.Kill()
-				defer pool.Put(event.Pkt)
-				if err := server.handlePacket(event.Peer, event.PktID, protocol.NewPacket(event.Pkt)); err != nil {
-					event.Peer.Kill()
-				}
 			}
+
+			// the packet is given to us by the event, so we'll need to make sure to return it to the pool
+			pool.Put(event.Pkt)
 		}
 	}
 }
@@ -143,7 +140,7 @@ func (server *ShardServer) connect(peer *protocol.CNPeer) {
 func (server *ShardServer) getPlayer(peer *protocol.CNPeer) (*entity.Player, error) {
 	plr, ok := server.peers[peer]
 	if !ok {
-		return nil, fmt.Errorf("Player not found")
+		return nil, fmt.Errorf("player not found")
 	}
 
 	return plr, nil