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feat: use streaming parser for frames
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,120 @@ | ||
| const { Writable } = require('stream') | ||
| const { parserStates } = require('./constants') | ||
|
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| class ByteParser extends Writable { | ||
| #buffers = [] | ||
| #byteOffset = 0 | ||
|
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| #state = parserStates.INFO | ||
|
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| #info = {} | ||
|
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| constructor (ws) { | ||
| super() | ||
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| this.ws = ws | ||
| } | ||
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| /** | ||
| * @param {Buffer} chunk | ||
| * @param {() => void} callback | ||
| */ | ||
| _write (chunk, _, callback) { | ||
| this.#buffers.push(chunk) | ||
| this.#byteOffset += chunk.length | ||
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| this.run(callback) | ||
| } | ||
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| /** | ||
| * Runs whenever a new chunk is received. | ||
| * Callback is called whenever there are no more chunks buffering, | ||
| * or not enough bytes are buffered to parse. | ||
| */ | ||
| run (callback) { | ||
| if (this.#state === parserStates.INFO) { | ||
| // If there aren't enough bytes to parse the payload length, etc. | ||
| if (this.#byteOffset < 2) { | ||
| return callback() | ||
| } | ||
|
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| const buffer = Buffer.concat(this.#buffers, this.#byteOffset) | ||
|
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| this.#info.fin = (buffer[0] & 0x80) !== 0 | ||
| this.#info.opcode = buffer[0] & 0x0F | ||
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| // TODO: HANDLE INVALID OPCODES HERE | ||
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| const payloadLength = buffer[1] & 0x7F | ||
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| if (payloadLength <= 125) { | ||
| this.#info.payloadLength = payloadLength | ||
| this.#state = parserStates.READ_DATA | ||
| } else if (payloadLength === 126) { | ||
| this.#state = parserStates.PAYLOADLENGTH_16 | ||
| } else if (payloadLength === 127) { | ||
| this.#state = parserStates.PAYLOADLENGTH_64 | ||
| } | ||
|
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| this.#buffers = [buffer.subarray(2)] | ||
| this.#byteOffset -= 2 | ||
| } else if (this.#state === parserStates.PAYLOADLENGTH_16) { | ||
| if (this.#byteOffset < 2) { | ||
| return callback() | ||
| } | ||
|
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| const buffer = Buffer.concat(this.#buffers, this.#byteOffset) | ||
|
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| // TODO: optimize this | ||
| this.#info.payloadLength = buffer.subarray(0, 2).readUInt16BE(0) | ||
| this.#state = parserStates.READ_DATA | ||
|
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| this.#buffers = [buffer.subarray(2)] | ||
| this.#byteOffset -= 2 | ||
| } else if (this.#state === parserStates.PAYLOADLENGTH_64) { | ||
| if (this.#byteOffset < 8) { | ||
| return callback() | ||
| } | ||
|
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| const buffer = Buffer.concat(this.#buffers, this.#byteOffset) | ||
|
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| // TODO: optimize this | ||
| this.#info.payloadLength = buffer.subarray(0, 8).readBigUint64BE(0) | ||
| this.#state = parserStates.READ_DATA | ||
|
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| this.#buffers = [buffer.subarray(8)] | ||
| this.#byteOffset -= 8 | ||
| } else if (this.#state === parserStates.READ_DATA) { | ||
| if (this.#byteOffset < this.#info.payloadLength) { | ||
| // If there is still more data in this chunk that needs to be read | ||
| return callback() | ||
| } else if (this.#byteOffset >= this.#info.payloadLength) { | ||
| // If the server sent multiple frames in a single chunk | ||
| const buffer = Buffer.concat(this.#buffers, this.#byteOffset) | ||
|
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| this.#info.data = buffer.subarray(0, this.#info.payloadLength) | ||
|
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| if (this.#byteOffset > this.#info.payloadLength) { | ||
| this.#buffers = [buffer.subarray(this.#info.data.length)] | ||
| this.#byteOffset -= this.#info.data.length | ||
| } else { | ||
| this.#buffers.length = 0 | ||
| this.#byteOffset = 0 | ||
| } | ||
|
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| this.#info = {} | ||
| this.#state = parserStates.INFO | ||
| } | ||
| } | ||
|
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| if (this.#byteOffset > 0) { | ||
| return this.run(callback) | ||
| } else { | ||
| callback() | ||
| } | ||
| } | ||
| } | ||
|
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| module.exports = { | ||
| ByteParser | ||
| } |
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