ModNet.cs

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using Newtonsoft.Json;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;
using ReLogic.Graphics;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using Terraria.ID;
using Terraria.Localization;
using Terraria.ModLoader.Config;
using Terraria.ModLoader.Core;
using Terraria.ModLoader.UI.DownloadManager;
using Terraria.ModLoader.UI;

namespace Terraria.ModLoader
{
    public static class ModNet
    {
        internal class ModHeader
        {
            public string name;
            public Version version;
            public byte[] hash;
            public bool signed;
            public string path;

            public ModHeader(string name, Version version, byte[] hash, bool signed) {
                this.name = name;
                this.version = version;
                this.hash = hash;
                this.signed = signed;
                path = Path.Combine(ModLoader.ModPath, name + ".tmod");
            }

            public bool Matches(TmodFile mod) => name == mod.name && version == mod.version && hash.SequenceEqual(mod.hash);
            public override string ToString() => name + " v" + version;
        }

        internal class NetConfig
        {
            public string modname;
            public string configname;
            public string json;

            public NetConfig(string modname, string configname, string json) {
                this.modname = modname;
                this.configname = configname;
                this.json = json;
            }
        }

        public static bool AllowVanillaClients { get; internal set; }
        internal static bool downloadModsFromServers = true;
        internal static bool onlyDownloadSignedMods = false;

        internal static bool[] isModdedClient = new bool[256];

        private static Mod[] netMods;

        public static bool IsModdedClient(int i) => isModdedClient[i];

        public static Mod GetMod(int netID) =>
            netID >= 0 && netID < netMods.Length ? netMods[netID] : null;

        public static int NetModCount => netMods.Length;

        private static Queue<ModHeader> downloadQueue = new Queue<ModHeader>();
        internal static List<NetConfig> pendingConfigs = new List<NetConfig>();
        private static ModHeader downloadingMod;
        private static FileStream downloadingFile;
        private static long downloadingLength;

        internal static void AssignNetIDs() {
            netMods = ModLoader.Mods.Where(mod => mod.Side != ModSide.Server).ToArray();
            for (short i = 0; i < netMods.Length; i++)
                netMods[i].netID = i;
        }

        internal static void Unload() {
            netMods = null;
            if (!Main.dedServ && Main.netMode != 1) //disable vanilla client compatibility restrictions when reloading on a client
                AllowVanillaClients = false;
        }

        internal static void SyncMods(int clientIndex) {
            var p = new ModPacket(MessageID.SyncMods);
            p.Write(AllowVanillaClients);

            var syncMods = ModLoader.Mods.Where(mod => mod.Side == ModSide.Both).ToList();
            AddNoSyncDeps(syncMods);

            p.Write(syncMods.Count);
            foreach (var mod in syncMods) { // We only sync ServerSide configs for ModSide.Both. ModSide.Server can have 
                p.Write(mod.Name);
                p.Write(mod.Version.ToString());
                p.Write(mod.File.hash);
                p.Write(mod.File.ValidModBrowserSignature);
                SendServerConfigs(p, mod);
            }

            p.Send(clientIndex);
        }

        private static void AddNoSyncDeps(List<Mod> syncMods) {
            var queue = new Queue<Mod>(syncMods.Where(m => m.Side == ModSide.Both));
            while (queue.Count > 0) {
                foreach (var dep in AssemblyManager.GetDependencies(queue.Dequeue())) {
                    if (dep.Side == ModSide.NoSync && !syncMods.Contains(dep)) {
                        syncMods.Add(dep);
                        queue.Enqueue(dep);
                    }
                }
            }
        }

        private static void SendServerConfigs(ModPacket p, Mod mod) {
            if (!ConfigManager.Configs.TryGetValue(mod, out var configs)) {
                p.Write(0);
                return;
            }

            var serverConfigs = configs.Where(x => x.Mode == ConfigScope.ServerSide).ToArray();
            p.Write(serverConfigs.Length);
            foreach (var config in serverConfigs) {
                string json = JsonConvert.SerializeObject(config, ConfigManager.serializerSettingsCompact);
                Logging.Terraria.Info($"Sending Server Config {config.mod.Name} {config.Name}: {json}");

                p.Write(config.Name);
                p.Write(json);
            }
        }

        internal static void SyncClientMods(BinaryReader reader) {
            if (!SyncClientMods(reader, out bool needsReload))
                return; //error syncing can't connect to server

            if (downloadQueue.Count > 0)
                DownloadNextMod();
            else
                OnModsDownloaded(needsReload);
        }

        // This method is split so that the local variables aren't held by the GC when reloading
        internal static bool SyncClientMods(BinaryReader reader, out bool needsReload) {
            AllowVanillaClients = reader.ReadBoolean();
            Logging.tML.Info($"Server reports AllowVanillaClients set to {AllowVanillaClients}");

            Main.statusText = Language.GetTextValue("tModLoader.MPSyncingMods");
            var clientMods = ModLoader.Mods;
            var modFiles = ModOrganizer.FindMods();
            needsReload = false;
            downloadQueue.Clear();
            pendingConfigs.Clear();
            var syncSet = new HashSet<string>();
            var blockedList = new List<ModHeader>();

            int n = reader.ReadInt32();
            for (int i = 0; i < n; i++) {
                var header = new ModHeader(reader.ReadString(), new Version(reader.ReadString()), reader.ReadBytes(20), reader.ReadBoolean());
                syncSet.Add(header.name);

                int configCount = reader.ReadInt32();
                for (int c = 0; c < configCount; c++)
                    pendingConfigs.Add(new NetConfig(header.name, reader.ReadString(), reader.ReadString()));

                var clientMod = clientMods.SingleOrDefault(m => m.Name == header.name);
                if (clientMod != null && header.Matches(clientMod.File))
                    continue;

                needsReload = true;

                var localVersions = modFiles.Where(m => m.Name == header.name).ToArray();
                var matching = Array.Find(localVersions, mod => header.Matches(mod.modFile));
                if (matching != null) {
                    matching.Enabled = true;
                    continue;
                }

                // overwrite an existing version of the mod if there is one
                if (localVersions.Length > 0)
                    header.path = localVersions[0].modFile.path;

                if (downloadModsFromServers && (header.signed || !onlyDownloadSignedMods))
                    downloadQueue.Enqueue(header);
                else
                    blockedList.Add(header);
            }

            foreach (var mod in clientMods)
                if (mod.Side == ModSide.Both && !syncSet.Contains(mod.Name)) {
                    ModLoader.DisableMod(mod.Name);
                    needsReload = true;
                }

            if (blockedList.Count > 0) {
                var msg = Language.GetTextValue("tModLoader.MPServerModsCantDownload");
                msg += downloadModsFromServers
                    ? Language.GetTextValue("tModLoader.MPServerModsCantDownloadReasonSigned")
                    : Language.GetTextValue("tModLoader.MPServerModsCantDownloadReasonAutomaticDownloadDisabled");
                msg += ".\n" + Language.GetTextValue("tModLoader.MPServerModsCantDownloadChangeSettingsHint") + "\n";
                foreach (var mod in blockedList)
                    msg += "\n    " + mod;

                Logging.tML.Warn(msg);
                Interface.errorMessage.Show(msg, 0);
                return false;
            }

            // ready to connect, apply configs. Config manager will apply the configs on reload automatically
            if (!needsReload) {
                foreach (var pendingConfig in pendingConfigs)
                    JsonConvert.PopulateObject(pendingConfig.json, ConfigManager.GetConfig(pendingConfig), ConfigManager.serializerSettingsCompact);

                if (ConfigManager.AnyModNeedsReload()) {
                    needsReload = true;
                }
                else {
                    foreach (var pendingConfig in pendingConfigs)
                        ConfigManager.GetConfig(pendingConfig).OnChanged();
                }
            }

            return true;
        }

        private static void DownloadNextMod() {
            downloadingMod = downloadQueue.Dequeue();
            downloadingFile = null;
            var p = new ModPacket(MessageID.ModFile);
            p.Write(downloadingMod.name);
            p.Send();
        }

        // Start sending the mod to the connecting client
        // First, send the initial mod name and length of the file stream
        // so the client knows what to expect
        internal const int CHUNK_SIZE = 16384;
        internal static void SendMod(string modName, int toClient) {
            var mod = ModLoader.GetMod(modName);
            var path = mod.File.path;
            var fs = File.OpenRead(path);
            {
                //send file length
                var p = new ModPacket(MessageID.ModFile);
                p.Write(mod.DisplayName);
                p.Write(fs.Length);
                p.Send(toClient);
            }

            var buf = new byte[CHUNK_SIZE];
            int count;
            while ((count = fs.Read(buf, 0, buf.Length)) > 0) {
                var p = new ModPacket(MessageID.ModFile, CHUNK_SIZE + 3);
                p.Write(buf, 0, count);
                p.Send(toClient);
            }

            fs.Close();
        }

        // Receive a mod when connecting to server
        internal static void ReceiveMod(BinaryReader reader) {
            if (downloadingMod == null)
                return;

            try {
                if (downloadingFile == null) {
                    Interface.progress.Show(displayText: reader.ReadString(), cancel: CancelDownload);

                    ModLoader.GetMod(downloadingMod.name)?.Close();
                    downloadingLength = reader.ReadInt64();
                    downloadingFile = new FileStream(downloadingMod.path, FileMode.Create);
                    return;
                }

                var bytes = reader.ReadBytes((int)Math.Min(downloadingLength - downloadingFile.Position, CHUNK_SIZE));
                downloadingFile.Write(bytes, 0, bytes.Length);
                Interface.progress.Progress = downloadingFile.Position / (float)downloadingLength;

                if (downloadingFile.Position == downloadingLength) {
                    downloadingFile.Close();
                    var mod = new TmodFile(downloadingMod.path);
                    using (mod.Open()) { }

                    if (!downloadingMod.Matches(mod))
                        throw new Exception(Language.GetTextValue("tModLoader.MPErrorModHashMismatch"));

                    if (downloadingMod.signed && !mod.ValidModBrowserSignature)
                        throw new Exception(Language.GetTextValue("tModLoader.MPErrorModNotSigned"));

                    ModLoader.EnableMod(mod.name);
                    if (downloadQueue.Count > 0) DownloadNextMod();
                    else OnModsDownloaded(true);
                }
            }
            catch (Exception e) {
                try {
                    downloadingFile?.Close();
                    File.Delete(downloadingMod.path);
                }
                catch (Exception exc2) {
                    Logging.tML.Error("Unknown error during mod sync", exc2);
                }

                var msg = Language.GetTextValue("tModLoader.MPErrorModDownloadError", downloadingMod.name);
                Logging.tML.Error(msg, e);
                Interface.errorMessage.Show(msg + e, 0);

                Netplay.disconnect = true;
                downloadingMod = null;
            }
        }

        private static void CancelDownload() {
            try {
                downloadingFile?.Close();
                File.Delete(downloadingMod.path);
            }
            catch { }
            downloadingMod = null;
            Netplay.disconnect = true;
        }

        private static void OnModsDownloaded(bool needsReload) {
            if (needsReload) {
                ModLoader.OnSuccessfulLoad = NetReload();
                ModLoader.Reload();
                return;
            }

            downloadingMod = null;
            netMods = null;
            foreach (var mod in ModLoader.Mods)
                mod.netID = -1;

            new ModPacket(MessageID.SyncMods).Send();
        }

        internal static Action NetReload() {
            // Main.ActivePlayerFileData gets cleared during reload
            var path = Main.ActivePlayerFileData.Path;
            var isCloudSave = Main.ActivePlayerFileData.IsCloudSave;
            return () => {
                // re-select the current player
                Player.GetFileData(path, isCloudSave).SetAsActive();
                //from Netplay.ClientLoopSetup
                Main.player[Main.myPlayer].hostile = false;
                Main.clientPlayer = (Player)Main.player[Main.myPlayer].clientClone();

                Main.menuMode = 10;
                OnModsDownloaded(false);
            };
        }

        internal static void SendNetIDs(int toClient) {
            var p = new ModPacket(MessageID.ModPacket);
            p.Write(netMods.Length);
            foreach (var mod in netMods)
                p.Write(mod.Name);

            ItemLoader.WriteNetGlobalOrder(p);
            WorldHooks.WriteNetWorldOrder(p);
            p.Write(Player.MaxBuffs);

            p.Send(toClient);
        }

        private static void ReadNetIDs(BinaryReader reader) {
            var mods = ModLoader.Mods;
            var list = new List<Mod>();
            var n = reader.ReadInt32();
            for (short i = 0; i < n; i++) {
                var name = reader.ReadString();
                var mod = mods.SingleOrDefault(m => m.Name == name);
                list.Add(mod);
                if (mod != null) //nosync mod that doesn't exist on the client
                    mod.netID = i;
            }
            netMods = list.ToArray();
            SetupDiagnostics();

            ItemLoader.ReadNetGlobalOrder(reader);
            WorldHooks.ReadNetWorldOrder(reader);
            int serverMaxBuffs = reader.ReadInt32();
            if (serverMaxBuffs != Player.MaxBuffs) {
                Netplay.disconnect = true;
                Main.statusText = $"The server expects Player.MaxBuffs of {serverMaxBuffs}\nbut this client reports {Player.MaxBuffs}.\nSome mod is behaving poorly.";
            }
        }

        // Some mods have expressed concern about read underflow exceptions conflicting with their ModPacket design, they can use reflection to set this bool as a bandaid until they fix their code.
        internal static bool ReadUnderflowBypass = false; // Remove by 0.11.7
        internal static void HandleModPacket(BinaryReader reader, int whoAmI, int length) {
            if (netMods == null) {
                ReadNetIDs(reader);
                return;
            }

            var id = NetModCount < 256 ? reader.ReadByte() : reader.ReadInt16();
            int start = (int)reader.BaseStream.Position;
            int actualLength = length - 1 - (NetModCount < 256 ? 1 : 2);
            try {
                ReadUnderflowBypass = false;
                GetMod(id)?.HandlePacket(reader, whoAmI);
                if (!ReadUnderflowBypass && reader.BaseStream.Position - start != actualLength) {
                    throw new IOException($"Read underflow {reader.BaseStream.Position - start} of {actualLength} bytes caused by {GetMod(id).Name} in HandlePacket");
                }
            }
            catch { }

            if (Main.netMode == 1) {
                rxMsgType[id]++;
                rxDataType[id] += length;
            }
        }

        internal static bool HijackGetData(ref byte messageType, ref BinaryReader reader, int playerNumber) {
            if (netMods == null) {
                return false;
            }

            bool hijacked = false;
            long readerPos = reader.BaseStream.Position;
            long biggestReaderPos = readerPos;
            foreach (var mod in ModLoader.Mods) {
                if (mod.HijackGetData(ref messageType, ref reader, playerNumber)) {
                    hijacked = true;
                    biggestReaderPos = Math.Max(reader.BaseStream.Position, biggestReaderPos);
                }
                reader.BaseStream.Position = readerPos;
            }
            if (hijacked) {
                reader.BaseStream.Position = biggestReaderPos;
            }
            return hijacked;
        }

        internal static bool HijackSendData(int whoAmI, int msgType, int remoteClient, int ignoreClient, NetworkText text, int number, float number2, float number3, float number4, int number5, int number6, int number7) {
            bool hijacked = false;
            foreach (Mod mod in ModLoader.Mods) {
                hijacked |= mod.HijackSendData(whoAmI, msgType, remoteClient, ignoreClient, text, number, number2, number3, number4, number5, number6, number7);
            }
            return hijacked;
        }

        // Mirror of Main class network diagnostic fields, but mod specific.
        // Potential improvements: separate page from vanilla messageIDs, track automatic/ModWorld/etc sends per class or mod, sort by most active, moving average, NetStats console command in ModLoaderMod
        // Currently we only update these on client
        public static int[] rxMsgType;
        public static int[] rxDataType;
        public static int[] txMsgType;
        public static int[] txDataType;

        private static void SetupDiagnostics() {
            rxMsgType = new int[netMods.Length];
            rxDataType = new int[netMods.Length];
            txMsgType = new int[netMods.Length];
            txDataType = new int[netMods.Length];
        }

        internal static void ResetNetDiag() {
            if (netMods == null || Main.netMode == 2) return;
            for (int i = 0; i < netMods.Length; i++) {
                rxMsgType[i] = 0;
                rxDataType[i] = 0;
                txMsgType[i] = 0;
                txDataType[i] = 0;
            }
        }

        internal static void DrawModDiagnoseNet() {
            if (netMods == null) return;
            float scale = 0.7f;

            for (int j = -1; j < netMods.Length; j++) {
                int i = j + Main.maxMsg + 2;
                int x = 200;
                int y = 120;
                int xAdjust = i / 50;
                x += xAdjust * 400;
                y += (i - xAdjust * 50) * 13;
                if (j == -1) {
                    Main.spriteBatch.DrawString(Main.fontMouseText, "Mod          Received(#, Bytes)     Sent(#, Bytes)", new Vector2((float)x, (float)y), Color.White, 0f, default(Vector2), scale, SpriteEffects.None, 0f);
                    continue;
                }
                Main.spriteBatch.DrawString(Main.fontMouseText, netMods[j].Name, new Vector2(x, y), Color.White, 0f, default(Vector2), scale, SpriteEffects.None, 0f);
                x += 120;
                Main.spriteBatch.DrawString(Main.fontMouseText, rxMsgType[j].ToString(), new Vector2(x, y), Color.White, 0f, default(Vector2), scale, SpriteEffects.None, 0f);
                x += 30;
                Main.spriteBatch.DrawString(Main.fontMouseText, rxDataType[j].ToString(), new Vector2(x, y), Color.White, 0f, default(Vector2), scale, SpriteEffects.None, 0f);
                x += 80;
                Main.spriteBatch.DrawString(Main.fontMouseText, txMsgType[j].ToString(), new Vector2(x, y), Color.White, 0f, default(Vector2), scale, SpriteEffects.None, 0f);
                x += 30;
                Main.spriteBatch.DrawString(Main.fontMouseText, txDataType[j].ToString(), new Vector2(x, y), Color.White, 0f, default(Vector2), scale, SpriteEffects.None, 0f);
            }
        }
    }
}