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99 lines
2.2 KiB
99 lines
2.2 KiB
/**
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* Returns a Buffer from a "ff 00 ff"-type hex string.
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*/
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getBufferFromHexString = function(byteStr) {
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var bytes = byteStr.split(' ');
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var buf = new Buffer(bytes.length);
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for (var i = 0; i < bytes.length; ++i) {
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buf[i] = parseInt(bytes[i], 16);
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}
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return buf;
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}
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/**
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* Returns a hex string from a Buffer.
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*/
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getHexStringFromBuffer = function(data) {
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var s = '';
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for (var i = 0; i < data.length; ++i) {
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s += padl(data[i].toString(16), 2, '0') + ' ';
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}
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return s.trim();
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}
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/**
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* Splits a buffer in two parts.
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*/
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splitBuffer = function(buffer) {
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var b1 = new Buffer(Math.ceil(buffer.length / 2));
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buffer.copy(b1, 0, 0, b1.length);
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var b2 = new Buffer(Math.floor(buffer.length / 2));
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buffer.copy(b2, 0, b1.length, b1.length + b2.length);
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return [b1, b2];
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}
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/**
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* Performs hybi07+ type masking on a hex string or buffer.
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*/
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mask = function(buf, maskString) {
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if (typeof buf == 'string') buf = new Buffer(buf);
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var mask = getBufferFromHexString(maskString || '34 83 a8 68');
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for (var i = 0; i < buf.length; ++i) {
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buf[i] ^= mask[i % 4];
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}
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return buf;
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}
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/**
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* Returns a hex string representing the length of a message
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*/
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getHybiLengthAsHexString = function(len, masked) {
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if (len < 126) {
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var buf = new Buffer(1);
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buf[0] = (masked ? 0x80 : 0) | len;
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}
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else if (len < 65536) {
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var buf = new Buffer(3);
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buf[0] = (masked ? 0x80 : 0) | 126;
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getBufferFromHexString(pack(4, len)).copy(buf, 1);
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}
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else {
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var buf = new Buffer(9);
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buf[0] = (masked ? 0x80 : 0) | 127;
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getBufferFromHexString(pack(16, len)).copy(buf, 1);
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}
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return getHexStringFromBuffer(buf);
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}
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/**
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* Unpacks a Buffer into a number.
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*/
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unpack = function(buffer) {
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var n = 0;
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for (var i = 0; i < buffer.length; ++i) {
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n = (i == 0) ? buffer[i] : (n * 256) + buffer[i];
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}
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return n;
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}
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/**
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* Returns a hex string, representing a specific byte count 'length', from a number.
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*/
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pack = function(length, number) {
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return padl(number.toString(16), length, '0').replace(/([0-9a-f][0-9a-f])/gi, '$1 ').trim();
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}
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/**
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* Left pads the string 's' to a total length of 'n' with char 'c'.
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*/
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padl = function(s, n, c) {
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return new Array(1 + n - s.length).join(c) + s;
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}
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