1 |
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2 |
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3 | var assert = require('assert');
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4 | var Buffer = require('safer-buffer').Buffer;
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5 |
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6 | var ASN1 = require('./types');
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7 | var errors = require('./errors');
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8 |
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9 |
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10 |
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11 |
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12 | var newInvalidAsn1Error = errors.newInvalidAsn1Error;
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13 |
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14 |
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15 |
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16 |
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17 |
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18 | function Reader(data) {
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19 | if (!data || !Buffer.isBuffer(data))
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20 | throw new TypeError('data must be a node Buffer');
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21 |
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22 | this._buf = data;
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23 | this._size = data.length;
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24 |
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25 |
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26 | this._len = 0;
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27 | this._offset = 0;
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28 | }
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29 |
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30 | Object.defineProperty(Reader.prototype, 'length', {
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31 | enumerable: true,
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32 | get: function () { return (this._len); }
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33 | });
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34 |
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35 | Object.defineProperty(Reader.prototype, 'offset', {
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36 | enumerable: true,
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37 | get: function () { return (this._offset); }
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38 | });
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39 |
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40 | Object.defineProperty(Reader.prototype, 'remain', {
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41 | get: function () { return (this._size - this._offset); }
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42 | });
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43 |
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44 | Object.defineProperty(Reader.prototype, 'buffer', {
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45 | get: function () { return (this._buf.slice(this._offset)); }
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46 | });
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47 |
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48 |
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49 |
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50 |
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51 |
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52 |
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53 |
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54 |
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55 |
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56 | Reader.prototype.readByte = function (peek) {
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57 | if (this._size - this._offset < 1)
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58 | return null;
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59 |
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60 | var b = this._buf[this._offset] & 0xff;
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61 |
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62 | if (!peek)
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63 | this._offset += 1;
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64 |
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65 | return b;
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66 | };
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67 |
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68 |
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69 | Reader.prototype.peek = function () {
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70 | return this.readByte(true);
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71 | };
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72 |
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73 |
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74 |
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75 |
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76 |
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77 |
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78 |
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79 |
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80 |
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81 |
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82 |
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83 |
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84 |
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85 | Reader.prototype.readLength = function (offset) {
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86 | if (offset === undefined)
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87 | offset = this._offset;
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88 |
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89 | if (offset >= this._size)
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90 | return null;
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91 |
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92 | var lenB = this._buf[offset++] & 0xff;
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93 | if (lenB === null)
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94 | return null;
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95 |
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96 | if ((lenB & 0x80) === 0x80) {
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97 | lenB &= 0x7f;
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98 |
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99 | if (lenB === 0)
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100 | throw newInvalidAsn1Error('Indefinite length not supported');
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101 |
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102 | if (lenB > 4)
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103 | throw newInvalidAsn1Error('encoding too long');
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104 |
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105 | if (this._size - offset < lenB)
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106 | return null;
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107 |
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108 | this._len = 0;
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109 | for (var i = 0; i < lenB; i++)
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110 | this._len = (this._len << 8) + (this._buf[offset++] & 0xff);
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111 |
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112 | } else {
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113 |
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114 | this._len = lenB;
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115 | }
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116 |
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117 | return offset;
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118 | };
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119 |
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120 |
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121 |
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122 |
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123 |
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124 |
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125 |
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126 |
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127 |
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128 | Reader.prototype.readSequence = function (tag) {
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129 | var seq = this.peek();
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130 | if (seq === null)
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131 | return null;
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132 | if (tag !== undefined && tag !== seq)
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133 | throw newInvalidAsn1Error('Expected 0x' + tag.toString(16) +
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134 | ': got 0x' + seq.toString(16));
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135 |
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136 | var o = this.readLength(this._offset + 1);
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137 | if (o === null)
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138 | return null;
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139 |
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140 | this._offset = o;
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141 | return seq;
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142 | };
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143 |
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144 |
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145 | Reader.prototype.readInt = function () {
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146 | return this._readTag(ASN1.Integer);
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147 | };
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148 |
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149 |
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150 | Reader.prototype.readBoolean = function () {
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151 | return (this._readTag(ASN1.Boolean) === 0 ? false : true);
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152 | };
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153 |
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154 |
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155 | Reader.prototype.readEnumeration = function () {
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156 | return this._readTag(ASN1.Enumeration);
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157 | };
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158 |
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159 |
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160 | Reader.prototype.readString = function (tag, retbuf) {
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161 | if (!tag)
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162 | tag = ASN1.OctetString;
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163 |
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164 | var b = this.peek();
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165 | if (b === null)
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166 | return null;
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167 |
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168 | if (b !== tag)
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169 | throw newInvalidAsn1Error('Expected 0x' + tag.toString(16) +
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170 | ': got 0x' + b.toString(16));
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171 |
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172 | var o = this.readLength(this._offset + 1);
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173 |
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174 | if (o === null)
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175 | return null;
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176 |
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177 | if (this.length > this._size - o)
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178 | return null;
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179 |
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180 | this._offset = o;
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181 |
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182 | if (this.length === 0)
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183 | return retbuf ? Buffer.alloc(0) : '';
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184 |
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185 | var str = this._buf.slice(this._offset, this._offset + this.length);
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186 | this._offset += this.length;
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187 |
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188 | return retbuf ? str : str.toString('utf8');
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189 | };
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190 |
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191 | Reader.prototype.readOID = function (tag) {
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192 | if (!tag)
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193 | tag = ASN1.OID;
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194 |
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195 | var b = this.readString(tag, true);
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196 | if (b === null)
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197 | return null;
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198 |
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199 | var values = [];
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200 | var value = 0;
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201 |
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202 | for (var i = 0; i < b.length; i++) {
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203 | var byte = b[i] & 0xff;
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204 |
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205 | value <<= 7;
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206 | value += byte & 0x7f;
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207 | if ((byte & 0x80) === 0) {
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208 | values.push(value);
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209 | value = 0;
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210 | }
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211 | }
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212 |
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213 | value = values.shift();
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214 | values.unshift(value % 40);
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215 | values.unshift((value / 40) >> 0);
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216 |
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217 | return values.join('.');
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218 | };
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219 |
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220 |
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221 | Reader.prototype._readTag = function (tag) {
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222 | assert.ok(tag !== undefined);
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223 |
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224 | var b = this.peek();
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225 |
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226 | if (b === null)
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227 | return null;
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228 |
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229 | if (b !== tag)
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230 | throw newInvalidAsn1Error('Expected 0x' + tag.toString(16) +
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231 | ': got 0x' + b.toString(16));
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232 |
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233 | var o = this.readLength(this._offset + 1);
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234 | if (o === null)
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235 | return null;
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236 |
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237 | if (this.length > 4)
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238 | throw newInvalidAsn1Error('Integer too long: ' + this.length);
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239 |
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240 | if (this.length > this._size - o)
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241 | return null;
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242 | this._offset = o;
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243 |
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244 | var fb = this._buf[this._offset];
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245 | var value = 0;
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246 |
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247 | for (var i = 0; i < this.length; i++) {
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248 | value <<= 8;
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249 | value |= (this._buf[this._offset++] & 0xff);
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250 | }
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251 |
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252 | if ((fb & 0x80) === 0x80 && i !== 4)
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253 | value -= (1 << (i * 8));
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254 |
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255 | return value >> 0;
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256 | };
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257 |
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258 |
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259 |
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260 |
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261 |
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262 | module.exports = Reader;
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