feat: add Shell

src/shell/algorithms/Raw.ts

@@ -0,0 +1,30 @@
+/*
+ * node-subdata-2 - SubData 2 wrapper for Node.js
+ * Copyright (C) 2022  LogN
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+import type ShellAlgorithm from "./ShellAlgorithm";
+
+/** The initial {@link ShellAlgorithm} used before any encryption is enabled. */
+export default class RawShellAlgorithm implements ShellAlgorithm {
+    public encode(data: Buffer): Buffer {
+        return data;
+    }
+
+    public decode(packet: Buffer): Buffer {
+        return packet;
+    }
+}

src/shell/algorithms/ShellAlgorithm.ts

@@ -0,0 +1,25 @@
+/*
+ * node-subdata-2 - SubData 2 wrapper for Node.js
+ * Copyright (C) 2022  LogN
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+/** Represents an algorithm for encoding/decoding data */
+export default interface ShellAlgorithm {
+    /** Encodes data into a packet */
+    encode(data: Buffer): Buffer;
+    /** Decodes a packet into data */
+    decode(packet: Buffer): Buffer;
+}

src/shell/index.ts

@@ -0,0 +1,65 @@
+/*
+ * node-subdata-2 - SubData 2 wrapper for Node.js
+ * Copyright (C) 2022  LogN
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+import SafeEventEmitter from "../lib/SafeEventEmitter";
+import type Stream from "../stream";
+import { StreamEvents } from "../stream";
+import type ShellAlgorithm from "./algorithms/ShellAlgorithm";
+
+export enum ShellEvents {
+    /** Fired when a new packet is received */
+    Packet = "packet",
+    /** Fired after a Read Reset */
+    Reset = "reset",
+    /** Fired when the underlying {@link Stream} closes */
+    Close = "close"
+}
+export type ShellEventArguments = {
+    [ShellEvents.Packet]: [number, Buffer];
+    [ShellEvents.Reset]: [];
+    [ShellEvents.Close]: [];
+};
+
+/**
+ * Represents and handles the {@link https://github.com/ME1312/SubData-2/wiki/Protocol-Format#layer-2-the-shell SubData 2 Shell}.
+ * Given an {@link ShellAlgorithm}, call it with data, and hook onto an {@link Stream}.
+ */
+export default class Shell extends SafeEventEmitter<ShellEventArguments> {
+    private _algorithm: ShellAlgorithm;
+    private _stream: Stream;
+
+    public constructor(algorithm: ShellAlgorithm, stream: Stream) {
+        super();
+        this._algorithm = algorithm;
+        this._stream = stream;
+        this._stream.on(StreamEvents.Close, () => {
+            this.emit(ShellEvents.Close);
+        });
+        this._stream.on(StreamEvents.Packet, (size, packet) => {
+            this.emit(ShellEvents.Packet, size, this._algorithm.decode(packet));
+        });
+        this._stream.on(StreamEvents.Close, () => {
+            this.emit(ShellEvents.Close);
+        });
+    }
+
+    /** Send a packet. */
+    public send(data: Buffer): void {
+        this._stream.writePacket(this._algorithm.encode(data));
+    }
+}