61 lines
2.2 KiB
TypeScript
61 lines
2.2 KiB
TypeScript
// Copyright (c) .NET Foundation. All rights reserved.
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// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
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import { HubMessage, IHubProtocol, ProtocolType } from "./IHubProtocol";
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export class Base64EncodedHubProtocol implements IHubProtocol {
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private wrappedProtocol: IHubProtocol;
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constructor(protocol: IHubProtocol) {
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this.wrappedProtocol = protocol;
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this.name = this.wrappedProtocol.name;
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this.type = ProtocolType.Text;
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}
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public readonly name: string;
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public readonly type: ProtocolType;
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public parseMessages(input: any): HubMessage[] {
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// The format of the message is `size:message;`
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const pos = input.indexOf(":");
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if (pos === -1 || input[input.length - 1] !== ";") {
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throw new Error("Invalid payload.");
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}
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const lenStr = input.substring(0, pos);
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if (!/^[0-9]+$/.test(lenStr)) {
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throw new Error(`Invalid length: '${lenStr}'`);
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}
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const messageSize = parseInt(lenStr, 10);
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// 2 accounts for ':' after message size and trailing ';'
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if (messageSize !== input.length - pos - 2) {
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throw new Error("Invalid message size.");
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}
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const encodedMessage = input.substring(pos + 1, input.length - 1);
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// atob/btoa are browsers APIs but they can be polyfilled. If this becomes problematic we can use
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// base64-js module
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const s = atob(encodedMessage);
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const payload = new Uint8Array(s.length);
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for (let i = 0; i < payload.length; i++) {
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payload[i] = s.charCodeAt(i);
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}
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return this.wrappedProtocol.parseMessages(payload.buffer);
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}
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public writeMessage(message: HubMessage): any {
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const payload = new Uint8Array(this.wrappedProtocol.writeMessage(message));
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let s = "";
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for (let i = 0; i < payload.byteLength; i++) {
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s += String.fromCharCode(payload[i]);
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}
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// atob/btoa are browsers APIs but they can be polyfilled. If this becomes problematic we can use
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// base64-js module
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const encodedMessage = btoa(s);
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return `${encodedMessage.length.toString()}:${encodedMessage};`;
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}
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}
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