116 lines
3.5 KiB
JavaScript
116 lines
3.5 KiB
JavaScript
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// for embedded scripts, quoted and modified from https://github.com/swansontec/rfc4648.js by William Swanson
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'use strict';
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var base64url = base64url || {};
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(function(base64url) {
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function parse (string, encoding, opts = {}) {
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// Build the character lookup table:
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if (!encoding.codes) {
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encoding.codes = {};
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for (let i = 0; i < encoding.chars.length; ++i) {
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encoding.codes[encoding.chars[i]] = i;
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}
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}
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// The string must have a whole number of bytes:
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if (!opts.loose && (string.length * encoding.bits) & 7) {
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throw new SyntaxError('Invalid padding');
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}
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// Count the padding bytes:
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let end = string.length;
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while (string[end - 1] === '=') {
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--end;
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// If we get a whole number of bytes, there is too much padding:
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if (!opts.loose && !(((string.length - end) * encoding.bits) & 7)) {
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throw new SyntaxError('Invalid padding');
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}
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}
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// Allocate the output:
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const out = new (opts.out || Uint8Array)(((end * encoding.bits) / 8) | 0);
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// Parse the data:
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let bits = 0; // Number of bits currently in the buffer
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let buffer = 0; // Bits waiting to be written out, MSB first
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let written = 0; // Next byte to write
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for (let i = 0; i < end; ++i) {
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// Read one character from the string:
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const value = encoding.codes[string[i]];
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if (value === void 0) {
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throw new SyntaxError('Invalid character ' + string[i]);
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}
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// Append the bits to the buffer:
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buffer = (buffer << encoding.bits) | value;
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bits += encoding.bits;
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// Write out some bits if the buffer has a byte's worth:
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if (bits >= 8) {
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bits -= 8;
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out[written++] = 0xff & (buffer >> bits);
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}
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}
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// Verify that we have received just enough bits:
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if (bits >= encoding.bits || 0xff & (buffer << (8 - bits))) {
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throw new SyntaxError('Unexpected end of data');
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}
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return out
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}
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function stringify (data, encoding, opts = {}) {
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const { pad = true } = opts;
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const mask = (1 << encoding.bits) - 1;
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let out = '';
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let bits = 0; // Number of bits currently in the buffer
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let buffer = 0; // Bits waiting to be written out, MSB first
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for (let i = 0; i < data.length; ++i) {
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// Slurp data into the buffer:
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buffer = (buffer << 8) | (0xff & data[i]);
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bits += 8;
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// Write out as much as we can:
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while (bits > encoding.bits) {
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bits -= encoding.bits;
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out += encoding.chars[mask & (buffer >> bits)];
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}
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}
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// Partial character:
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if (bits) {
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out += encoding.chars[mask & (buffer << (encoding.bits - bits))];
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}
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// Add padding characters until we hit a byte boundary:
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if (pad) {
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while ((out.length * encoding.bits) & 7) {
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out += '=';
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}
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}
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return out
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}
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const encoding = {
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chars: 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_',
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bits: 6
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}
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base64url.decode = function (string, opts) {
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return parse(string, encoding, opts);
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}
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base64url.encode = function (data, opts) {
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return stringify(data, encoding, opts)
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}
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return base64url;
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}(base64url));
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