'use strict';
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const { EMPTY_BUFFER } = require('./constants');
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/**
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* Merges an array of buffers into a new buffer.
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*
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* @param {Buffer[]} list The array of buffers to concat
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* @param {Number} totalLength The total length of buffers in the list
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* @return {Buffer} The resulting buffer
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* @public
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*/
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function concat(list, totalLength) {
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if (list.length === 0) return EMPTY_BUFFER;
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if (list.length === 1) return list[0];
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const target = Buffer.allocUnsafe(totalLength);
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var offset = 0;
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for (var i = 0; i < list.length; i++) {
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const buf = list[i];
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buf.copy(target, offset);
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offset += buf.length;
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}
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return target;
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}
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/**
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* Masks a buffer using the given mask.
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*
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* @param {Buffer} source The buffer to mask
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* @param {Buffer} mask The mask to use
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* @param {Buffer} output The buffer where to store the result
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* @param {Number} offset The offset at which to start writing
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* @param {Number} length The number of bytes to mask.
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* @public
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*/
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function _mask(source, mask, output, offset, length) {
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for (var i = 0; i < length; i++) {
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output[offset + i] = source[i] ^ mask[i & 3];
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}
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}
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/**
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* Unmasks a buffer using the given mask.
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*
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* @param {Buffer} buffer The buffer to unmask
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* @param {Buffer} mask The mask to use
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* @public
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*/
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function _unmask(buffer, mask) {
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// Required until https://github.com/nodejs/node/issues/9006 is resolved.
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const length = buffer.length;
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for (var i = 0; i < length; i++) {
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buffer[i] ^= mask[i & 3];
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}
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}
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/**
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* Converts a buffer to an `ArrayBuffer`.
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*
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* @param {Buffer} buf The buffer to convert
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* @return {ArrayBuffer} Converted buffer
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* @public
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*/
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function toArrayBuffer(buf) {
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if (buf.byteLength === buf.buffer.byteLength) {
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return buf.buffer;
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}
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return buf.buffer.slice(buf.byteOffset, buf.byteOffset + buf.byteLength);
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}
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/**
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* Converts `data` to a `Buffer`.
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*
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* @param {*} data The data to convert
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* @return {Buffer} The buffer
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* @throws {TypeError}
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* @public
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*/
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function toBuffer(data) {
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toBuffer.readOnly = true;
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if (Buffer.isBuffer(data)) return data;
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var buf;
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if (data instanceof ArrayBuffer) {
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buf = Buffer.from(data);
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} else if (ArrayBuffer.isView(data)) {
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buf = viewToBuffer(data);
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} else {
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buf = Buffer.from(data);
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toBuffer.readOnly = false;
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}
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return buf;
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}
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/**
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* Converts an `ArrayBuffer` view into a buffer.
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*
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* @param {(DataView|TypedArray)} view The view to convert
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* @return {Buffer} Converted view
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* @private
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*/
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function viewToBuffer(view) {
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const buf = Buffer.from(view.buffer);
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if (view.byteLength !== view.buffer.byteLength) {
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return buf.slice(view.byteOffset, view.byteOffset + view.byteLength);
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}
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return buf;
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}
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try {
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const bufferUtil = require('bufferutil');
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const bu = bufferUtil.BufferUtil || bufferUtil;
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module.exports = {
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concat,
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mask(source, mask, output, offset, length) {
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if (length < 48) _mask(source, mask, output, offset, length);
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else bu.mask(source, mask, output, offset, length);
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},
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toArrayBuffer,
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toBuffer,
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unmask(buffer, mask) {
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if (buffer.length < 32) _unmask(buffer, mask);
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else bu.unmask(buffer, mask);
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}
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};
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} catch (e) /* istanbul ignore next */ {
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module.exports = {
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concat,
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mask: _mask,
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toArrayBuffer,
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toBuffer,
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unmask: _unmask
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};
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}
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