Implement Eaglercraft skins

eaglerSkin.ts

@@ -0,0 +1,181 @@
+import {
+    encodeULEB128 as encodeVarInt,
+    decodeULEB128 as decodeVarInt,
+    encodeSLEB128 as encodeSVarInt,
+    decodeSLEB128 as decodeSVarInt
+} from "@thi.ng/leb128"
+import { DecodedCFetchSkin, DecodedSSkinDl, DecodedCSkinReq, DecodedSSkinFetchBuiltin, UnpackedChannelMessage, ProxiedPlayer, ChannelMessageType } from "./types.js"
+import uuidBuffer from "uuid-buffer"
+import { bufferizeUUID } from "./utils.js"
+import { EAGLERCRAFT_SKIN_CHANNEL_NAME, EaglerSkinPacketId, MAGIC_ENDING_S_SKINDL_BI } from "./eaglerPacketDef.js"
+import sharp from "sharp"
+import request from "request"
+
+export function unpackChannelMessage(message: Buffer): UnpackedChannelMessage {
+    if (message[0] != 0x17 && message[0] != 0x3f)
+        throw new Error("Invalid packet ID detected")
+    const ret: UnpackedChannelMessage = {
+        channel: null,
+        data: null,
+        type: null
+    }
+    const Iid = decodeVarInt(message)
+    const channelNameLen = decodeVarInt(message.subarray(Iid[1])), channelName = message.subarray(Iid[1] + channelNameLen[1], Iid[1] + channelNameLen[1] + Number(channelNameLen[0])).toString()
+    ret.type = Number(Iid[0])
+    ret.channel = channelName
+    ret.data = message.subarray(Iid[1] + channelNameLen[1] + channelName.length)
+    return ret
+}
+
+export function packChannelMessage(channel: string, type: ChannelMessageType, message: Buffer): Buffer {
+    const channelNameLen = encodeVarInt(channel.length), buff = Buffer.alloc(1 + channelNameLen.length + channel.length + message.length)
+    buff.set([type,...channelNameLen, ...Buffer.from(channel), ...message])
+    return buff
+}
+
+export function decodeCFetchSkin(message: Buffer): DecodedCFetchSkin {
+    const ret: DecodedCFetchSkin = {
+        id: null,
+        uuid: null
+    }
+    const Iid = decodeVarInt(message), uuid = uuidBuffer.toString(message.subarray(Iid[1]))
+    ret.id = Number(Iid[0])
+    ret.uuid = uuid
+    return ret
+}
+
+export function encodeFetchSkin(uuid: string | Buffer): Buffer {
+    uuid = typeof uuid == 'string' ? bufferizeUUID(uuid) : uuid
+    const buff = Buffer.alloc(1 + uuid.length)
+    buff.set([EaglerSkinPacketId.C_FETCH_SKIN, ...uuid])
+    return buff
+}
+
+export function decodeSSkinDlBuiltin(message: Buffer): DecodedSSkinFetchBuiltin {
+    const ret: DecodedSSkinFetchBuiltin = {
+        id: null,
+        uuid: null,
+        skinId: null
+    }
+    const Iid = decodeVarInt(message), uuid = uuidBuffer.toString(message.subarray(Iid[1], Iid[1] + 16))
+    ret.id = Number(Iid[0])
+    ret.uuid = uuid
+    const skinId = decodeVarInt(message.subarray(Iid[1] + 16 + 3))
+    ret.skinId = Number(skinId)
+    return ret
+}
+
+export function encodeSSkinDlBuiltin(uuid: string | Buffer, skinId: number): Buffer {
+    uuid = typeof uuid == 'string' ? bufferizeUUID(uuid) : uuid
+    const encSkinId = encodeVarInt(skinId)
+    const buff = Buffer.alloc(1 + 16 + 3 + encSkinId.length)
+    buff.set([EaglerSkinPacketId.S_SKIN_DL_BI, ...uuid, ...Buffer.from(MAGIC_ENDING_S_SKINDL_BI), encSkinId[0]])
+    return buff
+}
+
+export function decodeSSkinDl(message: Buffer): DecodedSSkinDl {
+    const ret: DecodedSSkinDl = {
+        id: null,
+        uuid: null,
+        skin: null
+    }
+    const Iid = decodeVarInt(message), uuid = uuidBuffer.toString(message.subarray(Iid[1], Iid[1] + 16))
+    ret.id = Number(Iid[0])
+    ret.uuid = uuid
+    const skin = message.subarray(Iid[1] + 16)
+    ret.skin = skin
+    return ret
+}
+
+export function encodeSSkinDl(uuid: string | Buffer, skin: Buffer, isFetched: boolean): Buffer {
+    uuid = typeof uuid == 'string' ? bufferizeUUID(uuid) : uuid
+    // eaglercraft clients always expect a 16385 byte long byte array for the skin
+    if (!isFetched) skin = skin.length !== 16384 ? skin.length < 16384 ? Buffer.concat([Buffer.alloc(16384 - skin.length), skin]) : skin.subarray(16383) : skin
+    else skin = skin.length !== 16384 ? skin.length < 16384 ? Buffer.concat([skin, Buffer.alloc(16384 - skin.length)]) : skin.subarray(16383) : skin
+    const skinLen = encodeVarInt(skin.length), buff = Buffer.alloc(1 + 16 + 1 + skin.length)
+    buff.set([EaglerSkinPacketId.S_SKIN_DL, ...uuid, 0xff,...skin])
+    return buff
+}
+
+export function decodeCSkinReq(message: Buffer): DecodedCSkinReq {
+    const ret: DecodedCSkinReq = {
+        id: null,
+        uuid: null,
+        url: null
+    }
+    const Iid = decodeVarInt(message), uuid = uuidBuffer.toString(message.subarray(Iid[1], Iid[1] + 16))
+    ret.id = Number(Iid[0])
+    ret.uuid = uuid
+    const urlLen = decodeVarInt(message.subarray(Iid[1] + 16 + 1)), url = message.subarray(Iid[1] + 16 + 1 + urlLen[1]).toString()
+    ret.url = url
+    return ret
+
+}
+
+export function encodeCSkinReq(uuid: string | Buffer, url: string): Buffer {
+    uuid = typeof uuid == 'string' ? bufferizeUUID(uuid) : uuid
+    const urlLen = encodeVarInt(url.length), eUrl = Buffer.from(url)
+    const buff = Buffer.alloc(1 + 1 + 16 + urlLen.length + eUrl.length)
+    buff.set([EaglerSkinPacketId.C_REQ_SKIN, ...uuid, 0x00, ...urlLen, ...eUrl])
+    return buff
+}
+
+// TODO: fix broken custom skins
+
+export async function fetchSkin(url: string): Promise<Buffer> {
+    return new Promise<Buffer>((res, rej) => {
+        let body = []
+        request({ url: url, encoding: null }, (err, response, body) => {
+            if (err) {
+                rej(err)
+            } else {
+                sharp(body)
+                    .resize(64, 64)
+                    .raw({ depth: 'char' })
+                    .toBuffer()
+                    .then(res)
+                    .catch(rej)
+            }
+        })
+    })
+}
+
+export function getPlayerWithUUID(uuid: string): ProxiedPlayer {
+    for (const [username, plr] of PROXY.players) {
+        if (plr.uuid == uuid)
+            return plr
+    }
+    return null
+}
+
+export async function processClientReqPacket(decodedMessage: UnpackedChannelMessage, client: ProxiedPlayer) {
+    if (decodedMessage.type == ChannelMessageType.SERVER)
+        throw new Error("Server message was passed to client message handler")
+    switch(decodedMessage.data[0] as EaglerSkinPacketId) {
+        default:
+            throw new Error("Unknown operation")
+            break
+        case EaglerSkinPacketId.C_REQ_SKIN:
+            const reqSkinPck = decodeCSkinReq(decodedMessage.data)
+            if (getPlayerWithUUID(reqSkinPck.uuid)) {
+                client.ws.send(packChannelMessage(EAGLERCRAFT_SKIN_CHANNEL_NAME, ChannelMessageType.SERVER, encodeSSkinDl(reqSkinPck.uuid, getPlayerWithUUID(reqSkinPck.uuid).skin.customSkin, false)))
+            } else {
+                try {
+                    const skin = await fetchSkin(reqSkinPck.url)
+                    const resPck = encodeSSkinDl(reqSkinPck.uuid, skin, true)
+                    client.ws.send(packChannelMessage(EAGLERCRAFT_SKIN_CHANNEL_NAME, ChannelMessageType.SERVER, resPck))
+                } catch {}
+            }
+            break
+        case EaglerSkinPacketId.C_FETCH_SKIN:
+            const fetchSkinPlrPck = decodeCFetchSkin(decodedMessage.data)
+            const plr = getPlayerWithUUID(fetchSkinPlrPck.uuid)
+            if (plr) {
+                if (plr.skin.type == 'BUILTIN') {
+                    client.ws.send(packChannelMessage(EAGLERCRAFT_SKIN_CHANNEL_NAME, ChannelMessageType.SERVER, encodeSSkinDlBuiltin(plr.uuid, plr.skin.skinId)))
+                } else {
+                    client.ws.send(packChannelMessage(EAGLERCRAFT_SKIN_CHANNEL_NAME, ChannelMessageType.SERVER, encodeSSkinDl(plr.uuid, plr.skin.customSkin, false)))
+                }
+            }
+    }
+}