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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,146 @@ | ||
| //import {Utility} from '../../misc/utility'; | ||
| const {Transform}=require('stream'); | ||
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| /** | ||
| * This parser reads the first 4 bytes and interprets it as (little endian) length. | ||
| * Then it collects 'length' further bytes. | ||
| * When all bytes have been received the data is emitted. | ||
| * This is the basic DZRP format. | ||
| * Is used here only for loopback testing. | ||
| */ | ||
| export class DzrpParser extends Transform { | ||
| /// State: Either waiting for length (false) or collecting data (true). | ||
| protected collectingData: boolean; | ||
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| /// The number of remaining bytes to collect. | ||
| protected remainingLength: number; | ||
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| /// Timeout. Max time between chunks. | ||
| protected timeout=1000; // ms | ||
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| /// The timer. | ||
| protected timer; | ||
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| // Name, for debugging purposes. | ||
| protected name: string|undefined; | ||
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| /// The constructor. | ||
| /// @param name Add a name for debugging purposes. | ||
| constructor(options={}, name?: string) { | ||
| super(options); | ||
| //Utility.assert(options); | ||
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| // Timeout | ||
| if ((options as any).timeout!=undefined) | ||
| this.timeout=(options as any).timeout; | ||
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| // Alloc buffer | ||
| this.buffer=Buffer.alloc(0); | ||
| this.collectingData=false; | ||
| this.remainingLength=0; | ||
| this.timer=undefined; | ||
| this.name=name; | ||
| } | ||
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| /** | ||
| * Creates an error text. | ||
| * I.e. Adds name and some constant text to it. | ||
| */ | ||
| public ErrorWithText(text: string): Error { | ||
| let wholeText="DZRP"; | ||
| if (this.name) | ||
| wholeText+=" ("+this.name+")"; | ||
| wholeText+=": "+text; | ||
| const err=new Error(wholeText); | ||
| return err; | ||
| } | ||
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| /** | ||
| * Clears the timer. | ||
| */ | ||
| public clearTimer() { | ||
| clearTimeout(this.timer); // Stop previous timer. | ||
| this.timer=undefined; | ||
| } | ||
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| /** | ||
| * Should be started a soon as a response is expected. | ||
| * @param errorText The text that is emitted if the timer expires. | ||
| */ | ||
| public startTimer(errorText: string) { | ||
| clearTimeout(this.timer); // Stop previous timer. | ||
| this.timer=setTimeout(() => { | ||
| this.emit('error', this.ErrorWithText('Timeout: ' + errorText)); | ||
| }, this.timeout); | ||
| } | ||
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| /** | ||
| * Read chunks of data until a complete message has been received. | ||
| */ | ||
| _transform(chunk, encoding, cb) { | ||
| // Stop timer | ||
| //console.log(this.name, "0 clear timer, remainingLength=", this.remainingLength, "chunk=", chunk.length, ", buffer=", this.buffer.length, chunk); | ||
| clearTimeout(this.timer); | ||
| this.timer=undefined; | ||
| // Concat data | ||
| this.buffer=Buffer.concat([this.buffer, chunk]) | ||
| while (true) { | ||
| // Check state | ||
| if (!this.collectingData) { | ||
| // Check if all 4 bytes have been received | ||
| if (this.buffer.length<4) | ||
| break; | ||
| const data=this.buffer; | ||
| this.remainingLength=data[0]+(data[1]<<8)+(data[2]<<16)+(data[3]*256*65536); // Note: <<24 might return a negative value | ||
| //console.log(this.name, "0b new message, (remaining)Length=", this.remainingLength); | ||
| this.buffer=this.buffer.subarray(4); | ||
| this.collectingData=true; | ||
| } | ||
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| // Collect until all remaining bytes received | ||
| const count=this.buffer.length; | ||
| if (count<this.remainingLength) | ||
| break; | ||
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| // Enough data | ||
| this.collectingData=false; | ||
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| // Check if there was too many data received | ||
| let data=this.buffer; | ||
| if (count>this.remainingLength) { | ||
| data=data.subarray(0, this.remainingLength); | ||
| } | ||
| // Enough data collected | ||
| //console.log(this.name, "1 push, remainingLength=", this.remainingLength, ", buffer=", this.buffer.length); | ||
| this.push(data); | ||
| //console.log(this.name, "2a remainingLength=", this.remainingLength, ", buffer=", this.buffer.length); | ||
| this.buffer=this.buffer.subarray(this.remainingLength); // Normally clears the buffer | ||
| this.remainingLength=this.buffer.length; | ||
| //console.log(this.name, "2b remainingLength=", this.remainingLength, ", buffer=", this.buffer.length); | ||
| } | ||
| // Start timeout | ||
| if (this.remainingLength>0) { | ||
| this.startTimer('Too much time between two data chunks.'); | ||
| //console.log(this.name, "3a set timer"); | ||
| } | ||
| // Call callback | ||
| //console.log(this.name, "3b return, remainingLength=", this.remainingLength, ", buffer=", this.buffer.length); | ||
| cb(); | ||
| } | ||
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| _flush(cb) { | ||
| this.push(this.buffer) | ||
| this.buffer=Buffer.alloc(0) | ||
| cb() | ||
| } | ||
| } | ||
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