1 | // Copyright (c) Microsoft. All rights reserved.
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2 | // Licensed under the MIT license. See LICENSE file in the project root for full license information.
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3 |
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4 | #include <stdlib.h>
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5 | #include <stdio.h>
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6 | #include <string.h>
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7 | #include "azure_c_shared_utility/gballoc.h"
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8 | #include "azure_c_shared_utility/sastoken.h"
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9 | #include "azure_c_shared_utility/urlencode.h"
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10 | #include "azure_c_shared_utility/hmacsha256.h"
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11 | #include "azure_c_shared_utility/azure_base64.h"
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12 | #include "azure_c_shared_utility/agenttime.h"
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13 | #include "azure_c_shared_utility/strings.h"
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14 | #include "azure_c_shared_utility/buffer_.h"
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15 | #include "azure_c_shared_utility/xlogging.h"
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16 | #include "azure_c_shared_utility/crt_abstractions.h"
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17 |
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18 | static double getExpiryValue(const char* expiryASCII)
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19 | {
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20 | double value = 0;
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21 | size_t i = 0;
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22 | for (i = 0; expiryASCII[i] != '\0'; i++)
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23 | {
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24 | if (expiryASCII[i] >= '0' && expiryASCII[i] <= '9')
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25 | {
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26 | value = value * 10 + (double)(expiryASCII[i] - '0');
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27 | }
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28 | else
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29 | {
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30 | value = 0;
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31 | break;
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32 | }
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33 | }
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34 | return value;
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35 | }
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36 |
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37 | bool SASToken_Validate(STRING_HANDLE sasToken)
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38 | {
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39 | bool result;
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40 | /*Codes_SRS_SASTOKEN_25_025: [**SASToken_Validate shall get the SASToken value by invoking STRING_c_str on the handle.**]***/
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41 | const char* sasTokenArray = STRING_c_str(sasToken);
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42 |
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43 | /* Codes_SRS_SASTOKEN_25_024: [**If handle is NULL then SASToken_Validate shall return false.**] */
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44 | /* Codes_SRS_SASTOKEN_25_026: [**If STRING_c_str on handle return NULL then SASToken_Validate shall return false.**] */
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45 | if (sasToken == NULL || sasTokenArray == NULL)
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46 | {
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47 | result = false;
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48 | }
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49 | else
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50 | {
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51 | int seStart = -1, seStop = -1;
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52 | int srStart = -1, srStop = -1;
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53 | int sigStart = -1, sigStop = -1;
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54 | int tokenLength = (int)STRING_length(sasToken);
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55 | int i;
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56 | for (i = 0; i < tokenLength; i++)
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57 | {
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58 | if (sasTokenArray[i] == 's' && sasTokenArray[i + 1] == 'e' && sasTokenArray[i + 2] == '=') // Look for se=
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59 | {
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60 | seStart = i + 3;
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61 | if (srStart > 0 && srStop < 0)
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62 | {
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63 | if (sasTokenArray[i - 1] != '&' && sasTokenArray[i - 1] == ' ') // look for either & or space
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64 | srStop = i - 1;
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65 | else if (sasTokenArray[i - 1] == '&')
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66 | srStop = i - 2;
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67 | else
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68 | seStart = -1; // as the format is not either "&se=" or " se="
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69 | }
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70 | else if (sigStart > 0 && sigStop < 0)
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71 | {
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72 | if (sasTokenArray[i - 1] != '&' && sasTokenArray[i - 1] == ' ')
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73 | sigStop = i - 1;
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74 | else if (sasTokenArray[i - 1] == '&')
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75 | sigStop = i - 2;
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76 | else
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77 | seStart = -1;
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78 | }
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79 | }
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80 | else if (sasTokenArray[i] == 's' && sasTokenArray[i + 1] == 'r' && sasTokenArray[i + 2] == '=') // Look for sr=
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81 | {
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82 | srStart = i + 3;
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83 | if (seStart > 0 && seStop < 0)
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84 | {
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85 | if (sasTokenArray[i - 1] != '&' && sasTokenArray[i - 1] == ' ')
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86 | seStop = i - 1;
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87 | else if (sasTokenArray[i - 1] == '&')
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88 | seStop = i - 2;
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89 | else
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90 | srStart = -1;
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91 | }
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92 | else if (sigStart > 0 && sigStop < 0)
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93 | {
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94 | if (sasTokenArray[i - 1] != '&' && sasTokenArray[i - 1] == ' ')
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95 | sigStop = i - 1;
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96 | else if (sasTokenArray[i - 1] == '&')
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97 | sigStop = i - 2;
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98 | else
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99 | srStart = -1;
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100 | }
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101 | }
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102 | else if (sasTokenArray[i] == 's' && sasTokenArray[i + 1] == 'i' && sasTokenArray[i + 2] == 'g' && sasTokenArray[i + 3] == '=') // Look for sig=
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103 | {
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104 | sigStart = i + 4;
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105 | if (srStart > 0 && srStop < 0)
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106 | {
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107 | if (sasTokenArray[i - 1] != '&' && sasTokenArray[i - 1] == ' ')
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108 | srStop = i - 1;
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109 | else if (sasTokenArray[i - 1] == '&')
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110 | srStop = i - 2;
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111 | else
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112 | sigStart = -1;
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113 | }
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114 | else if (seStart > 0 && seStop < 0)
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115 | {
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116 | if (sasTokenArray[i - 1] != '&' && sasTokenArray[i - 1] == ' ')
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117 | seStop = i - 1;
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118 | else if (sasTokenArray[i - 1] == '&')
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119 | seStop = i - 2;
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120 | else
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121 | sigStart = -1;
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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 | /*Codes_SRS_SASTOKEN_25_027: [**If SASTOKEN does not obey the SASToken format then SASToken_Validate shall return false.**]***/
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127 | /*Codes_SRS_SASTOKEN_25_028: [**SASToken_validate shall check for the presence of sr, se and sig from the token and return false if not found**]***/
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128 | if (seStart < 0 || srStart < 0 || sigStart < 0)
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129 | {
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130 | result = false;
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131 | }
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132 | else
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133 | {
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134 | if (seStop < 0)
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135 | {
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136 | seStop = tokenLength;
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137 | }
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138 | else if (srStop < 0)
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139 | {
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140 | srStop = tokenLength;
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141 | }
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142 | else if (sigStop < 0)
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143 | {
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144 | sigStop = tokenLength;
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145 | }
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146 |
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147 | if ((seStop <= seStart) ||
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148 | (srStop <= srStart) ||
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149 | (sigStop <= sigStart))
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150 | {
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151 | result = false;
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152 | }
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153 | else
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154 | {
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155 | char* expiryASCII = (char*)malloc(seStop - seStart + 1);
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156 | /*Codes_SRS_SASTOKEN_25_031: [**If malloc fails during validation then SASToken_Validate shall return false.**]***/
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157 | if (expiryASCII == NULL)
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158 | {
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159 | result = false;
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160 | }
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161 | else
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162 | {
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163 | double expiry;
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164 | // Add the Null terminator here
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165 | memset(expiryASCII, 0, seStop - seStart + 1);
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166 | for (i = seStart; i < seStop; i++)
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167 | {
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168 | // The se contains the expiration values, if a & token is encountered then
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169 | // the se field is complete.
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170 | if (sasTokenArray[i] == '&')
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171 | {
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172 | break;
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173 | }
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174 | expiryASCII[i - seStart] = sasTokenArray[i];
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175 | }
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176 | expiry = getExpiryValue(expiryASCII);
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177 | /*Codes_SRS_SASTOKEN_25_029: [**SASToken_validate shall check for expiry time from token and if token has expired then would return false **]***/
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178 | if (expiry <= 0)
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179 | {
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180 | result = false;
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181 | }
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182 | else
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183 | {
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184 | double secSinceEpoch = get_difftime(get_time(NULL), (time_t)0);
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185 | if (expiry < secSinceEpoch)
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186 | {
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187 | /*Codes_SRS_SASTOKEN_25_029: [**SASToken_validate shall check for expiry time from token and if token has expired then would return false **]***/
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188 | result = false;
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189 | }
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190 | else
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191 | {
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192 | /*Codes_SRS_SASTOKEN_25_030: [**SASToken_validate shall return true only if the format is obeyed and the token has not yet expired **]***/
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193 | result = true;
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194 | }
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195 | }
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196 | free(expiryASCII);
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197 | }
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198 | }
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199 | }
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200 | }
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201 |
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202 | return result;
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203 | }
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204 |
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205 | static STRING_HANDLE construct_sas_token(const char* key, const char* scope, const char* keyname, size_t expiry)
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206 | {
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207 | STRING_HANDLE result;
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208 |
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209 | char tokenExpirationTime[32] = { 0 };
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210 |
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211 | BUFFER_HANDLE decodedKey;
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212 |
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213 | /*Codes_SRS_SASTOKEN_06_029: [The key parameter is decoded from base64.]*/
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214 | if ((decodedKey = Azure_Base64_Decode(key)) == NULL)
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215 | {
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216 | /*Codes_SRS_SASTOKEN_06_030: [If there is an error in the decoding then SASToken_Create shall return NULL.]*/
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217 | LogError("Unable to decode the key for generating the SAS.");
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218 | result = NULL;
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219 | }
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220 | else
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221 | {
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222 | /*Codes_SRS_SASTOKEN_06_026: [If the conversion to string form fails for any reason then SASToken_Create shall return NULL.]*/
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223 | if (size_tToString(tokenExpirationTime, sizeof(tokenExpirationTime), expiry) != 0)
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224 | {
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225 | LogError("For some reason converting seconds to a string failed. No SAS can be generated.");
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226 | result = NULL;
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227 | }
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228 | else
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229 | {
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230 | STRING_HANDLE toBeHashed = NULL;
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231 | BUFFER_HANDLE hash = NULL;
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232 | if (((hash = BUFFER_new()) == NULL) ||
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233 | ((toBeHashed = STRING_new()) == NULL) ||
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234 | ((result = STRING_new()) == NULL))
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235 | {
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236 | LogError("Unable to allocate memory to prepare SAS token.");
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237 | result = NULL;
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238 | }
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239 | else
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240 | {
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241 | /*Codes_SRS_SASTOKEN_06_009: [The scope is the basis for creating a STRING_HANDLE.]*/
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242 | /*Codes_SRS_SASTOKEN_06_010: [A "\n" is appended to that string.]*/
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243 | /*Codes_SRS_SASTOKEN_06_011: [tokenExpirationTime is appended to that string.]*/
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244 | if ((STRING_concat(toBeHashed, scope) != 0) ||
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245 | (STRING_concat(toBeHashed, "\n") != 0) ||
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246 | (STRING_concat(toBeHashed, tokenExpirationTime) != 0))
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247 | {
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248 | LogError("Unable to build the input to the HMAC to prepare SAS token.");
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249 | STRING_delete(result);
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250 | result = NULL;
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251 | }
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252 | else
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253 | {
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254 | STRING_HANDLE base64Signature = NULL;
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255 | STRING_HANDLE urlEncodedSignature = NULL;
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256 | size_t inLen = STRING_length(toBeHashed);
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257 | const unsigned char* inBuf = (const unsigned char*)STRING_c_str(toBeHashed);
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258 | size_t outLen = BUFFER_length(decodedKey);
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259 | unsigned char* outBuf = BUFFER_u_char(decodedKey);
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260 | /*Codes_SRS_SASTOKEN_06_013: [If an error is returned from the HMAC256 function then NULL is returned from SASToken_Create.]*/
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261 | /*Codes_SRS_SASTOKEN_06_012: [An HMAC256 hash is calculated using the decodedKey, over toBeHashed.]*/
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262 | /*Codes_SRS_SASTOKEN_06_014: [If there are any errors from the following operations then NULL shall be returned.]*/
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263 | /*Codes_SRS_SASTOKEN_06_015: [The hash is base 64 encoded.]*/
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264 | /*Codes_SRS_SASTOKEN_06_028: [base64Signature shall be url encoded.]*/
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265 | /*Codes_SRS_SASTOKEN_06_016: [The string "SharedAccessSignature sr=" is the first part of the result of SASToken_Create.]*/
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266 | /*Codes_SRS_SASTOKEN_06_017: [The scope parameter is appended to result.]*/
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267 | /*Codes_SRS_SASTOKEN_06_018: [The string "&sig=" is appended to result.]*/
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268 | /*Codes_SRS_SASTOKEN_06_019: [The string urlEncodedSignature shall be appended to result.]*/
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269 | /*Codes_SRS_SASTOKEN_06_020: [The string "&se=" shall be appended to result.]*/
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270 | /*Codes_SRS_SASTOKEN_06_021: [tokenExpirationTime is appended to result.]*/
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271 | /*Codes_SRS_SASTOKEN_06_022: [If keyName is non-NULL, the string "&skn=" is appended to result.]*/
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272 | /*Codes_SRS_SASTOKEN_06_023: [If keyName is non-NULL, the argument keyName is appended to result.]*/
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273 | if ((HMACSHA256_ComputeHash(outBuf, outLen, inBuf, inLen, hash) != HMACSHA256_OK) ||
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274 | ((base64Signature = Azure_Base64_Encode(hash)) == NULL) ||
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275 | ((urlEncodedSignature = URL_Encode(base64Signature)) == NULL) ||
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276 | (STRING_copy(result, "SharedAccessSignature sr=") != 0) ||
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277 | (STRING_concat(result, scope) != 0) ||
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278 | (STRING_concat(result, "&sig=") != 0) ||
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279 | (STRING_concat_with_STRING(result, urlEncodedSignature) != 0) ||
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280 | (STRING_concat(result, "&se=") != 0) ||
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281 | (STRING_concat(result, tokenExpirationTime) != 0) ||
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282 | ((keyname != NULL) && (STRING_concat(result, "&skn=") != 0)) ||
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283 | ((keyname != NULL) && (STRING_concat(result, keyname) != 0)))
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284 | {
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285 | LogError("Unable to build the SAS token.");
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286 | STRING_delete(result);
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287 | result = NULL;
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288 | }
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289 | else
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290 | {
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291 | /* everything OK */
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292 | }
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293 | STRING_delete(base64Signature);
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294 | STRING_delete(urlEncodedSignature);
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295 | }
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296 | }
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297 | STRING_delete(toBeHashed);
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298 | BUFFER_delete(hash);
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299 | }
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300 | BUFFER_delete(decodedKey);
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301 | }
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302 | return result;
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303 | }
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304 |
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305 | STRING_HANDLE SASToken_Create(STRING_HANDLE key, STRING_HANDLE scope, STRING_HANDLE keyName, size_t expiry)
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306 | {
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307 | STRING_HANDLE result;
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308 |
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309 | /*Codes_SRS_SASTOKEN_06_001: [If key is NULL then SASToken_Create shall return NULL.]*/
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310 | /*Codes_SRS_SASTOKEN_06_003: [If scope is NULL then SASToken_Create shall return NULL.]*/
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311 | /*Codes_SRS_SASTOKEN_06_007: [keyName is optional and can be set to NULL.]*/
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312 | if ((key == NULL) ||
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313 | (scope == NULL))
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314 | {
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315 | LogError("Invalid Parameter to SASToken_Create. handle key: %p, handle scope: %p, handle keyName: %p", key, scope, keyName);
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316 | result = NULL;
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317 | }
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318 | else
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319 | {
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320 | const char* string_key = STRING_c_str(key);
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321 | const char* string_scope = STRING_c_str(scope);
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322 | const char* string_name = STRING_c_str(keyName);
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323 | result = construct_sas_token(string_key, string_scope, string_name, expiry);
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324 | }
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325 | return result;
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326 | }
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327 |
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328 | STRING_HANDLE SASToken_CreateString(const char* key, const char* scope, const char* keyName, size_t expiry)
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329 | {
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330 | STRING_HANDLE result;
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331 |
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332 | /*Codes_SRS_SASTOKEN_06_001: [If key is NULL then SASToken_Create shall return NULL.]*/
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333 | /*Codes_SRS_SASTOKEN_06_003: [If scope is NULL then SASToken_Create shall return NULL.]*/
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334 | /*Codes_SRS_SASTOKEN_06_007: [keyName is optional and can be set to NULL.]*/
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335 | if ((key == NULL) ||
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336 | (scope == NULL))
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337 | {
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338 | LogError("Invalid Parameter to SASToken_Create. handle key: %p, handle scope: %p, handle keyName: %p", key, scope, keyName);
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339 | result = NULL;
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340 | }
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341 | else
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342 | {
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343 | result = construct_sas_token(key, scope, keyName, expiry);
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344 | }
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345 | return result;
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346 | }
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