Diff: azure_c_shared_utility/sastoken.c

Revision:

3:c0556ff7b8e3

diff -r 2b9acda15ef0 -r c0556ff7b8e3 azure_c_shared_utility/sastoken.c
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/azure_c_shared_utility/sastoken.c	Thu Dec 08 00:11:40 2016 +0000
@@ -0,0 +1,309 @@
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+#ifdef _CRTDBG_MAP_ALLOC
+#include <crtdbg.h>
+#endif
+
+#include "azure_c_shared_utility/gballoc.h"
+#include "azure_c_shared_utility/sastoken.h"
+#include "azure_c_shared_utility/urlencode.h"
+#include "azure_c_shared_utility/hmacsha256.h"
+#include "azure_c_shared_utility/base64.h"
+#include "azure_c_shared_utility/agenttime.h"
+#include "azure_c_shared_utility/strings.h"
+#include "azure_c_shared_utility/buffer_.h"
+#include "azure_c_shared_utility/xlogging.h"
+#include "azure_c_shared_utility/crt_abstractions.h"
+
+static double getExpiryValue(const char* expiryASCII)
+{
+    double value = 0;
+    size_t i = 0;
+    for (i = 0; expiryASCII[i] != '\0'; i++)
+    {
+        if (expiryASCII[i] >= '0' && expiryASCII[i] <= '9')
+        {
+            value = value * 10 + (expiryASCII[i] - '0');
+        }
+        else
+        {
+            value = 0;
+            break;
+        }
+    }
+    return value;
+}
+
+bool SASToken_Validate(STRING_HANDLE sasToken)
+{
+    bool result;
+    /*Codes_SRS_SASTOKEN_25_025: [**SASToken_Validate shall get the SASToken value by invoking STRING_c_str on the handle.**]***/
+    const char* sasTokenArray = STRING_c_str(sasToken);
+
+    /***Codes_SRS_SASTOKEN_25_024: [**If handle is NULL then SASToken_Validate shall return false.**] ***/
+    /*Codes_SRS_SASTOKEN_25_026: [**If STRING_c_str on handle return NULL then SASToken_Validate shall return false.**]***/
+    if (sasToken == NULL || sasTokenArray == NULL)
+    {
+        result = false;
+    }
+    else
+    {
+        int seStart = -1, seStop = -1;
+        int srStart = -1, srStop = -1;
+        int sigStart = -1, sigStop = -1;
+        int tokenLength = (int) STRING_length(sasToken);
+        int i ;
+        for (i = 0; i < tokenLength; i++)
+        {
+            if (sasTokenArray[i] == 's' && sasTokenArray[i + 1] == 'e' && sasTokenArray[i + 2] == '=') // Look for se=
+            {
+                seStart = i + 3;
+                if (srStart > 0 && srStop < 0)
+                {
+                    if (sasTokenArray[i - 1] != '&' && sasTokenArray[i - 1] == ' ') // look for either & or space
+                        srStop = i - 1;
+                    else if (sasTokenArray[i - 1] == '&')
+                        srStop = i - 2;
+                    else
+                        seStart = -1; // as the format is not either "&se=" or " se="
+                }
+                else if (sigStart > 0 && sigStop < 0)
+                {
+                    if (sasTokenArray[i - 1] != '&' && sasTokenArray[i - 1] == ' ')
+                        sigStop = i - 1;
+                    else if (sasTokenArray[i - 1] == '&')
+                        sigStop = i - 2;
+                    else
+                        seStart = -1;
+                }
+                continue;
+            }
+            if (sasTokenArray[i] == 's' && sasTokenArray[i + 1] == 'r' && sasTokenArray[i + 2] == '=') // Look for sr=
+            {
+                srStart = i + 3;
+                if (seStart > 0 && seStop < 0)
+                {
+                    if (sasTokenArray[i - 1] != '&' && sasTokenArray[i - 1] == ' ')
+                        seStop = i - 1;
+                    else if (sasTokenArray[i - 1] == '&')
+                        seStop = i - 2;
+                    else
+                        srStart = -1;
+                }
+                else if (sigStart > 0 && sigStop < 0)
+                {
+                    if (sasTokenArray[i - 1] != '&' && sasTokenArray[i - 1] == ' ')
+                        sigStop = i - 1;
+                    else if (sasTokenArray[i - 1] == '&')
+                        sigStop = i - 2;
+                    else
+                        srStart = -1;
+                }
+                continue;
+            }
+            if (sasTokenArray[i] == 's' && sasTokenArray[i + 1] == 'i' && sasTokenArray[i + 2] == 'g' && sasTokenArray[i + 3] == '=') // Look for sig=
+            {
+                sigStart = i + 4;
+                if (srStart > 0 && srStop < 0)
+                {
+                    if (sasTokenArray[i - 1] != '&' && sasTokenArray[i - 1] == ' ')
+                        srStop = i - 1;
+                    else if (sasTokenArray[i - 1] == '&')
+                        srStop = i - 2;
+                    else
+                        sigStart = -1;
+                }
+                else if (seStart > 0 && seStop < 0)
+                {
+                    if (sasTokenArray[i - 1] != '&' && sasTokenArray[i - 1] == ' ')
+                        seStop = i - 1;
+                    else if (sasTokenArray[i - 1] == '&')
+                        seStop = i - 2;
+                    else
+                        sigStart = -1;
+                }
+                continue;
+            }
+        }
+        /*Codes_SRS_SASTOKEN_25_027: [**If SASTOKEN does not obey the SASToken format then SASToken_Validate shall return false.**]***/
+        /*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**]***/
+        if (seStart < 0 || srStart < 0 || sigStart < 0)
+        {
+            result = false;
+        }
+        else
+        {
+            if (seStop < 0)
+            {
+                seStop = tokenLength;
+            }
+            else if (srStop < 0)
+            {
+                srStop = tokenLength;
+            }
+            else if (sigStop < 0)
+            {
+                sigStop = tokenLength;
+            }
+
+            if ((seStop <= seStart) ||
+                (srStop <= srStart) ||
+                (sigStop <= sigStart))
+            {
+                result = false;
+            }
+            else
+            {
+                char* expiryASCII = malloc(seStop - seStart + 1);
+                /*Codes_SRS_SASTOKEN_25_031: [**If malloc fails during validation then SASToken_Validate shall return false.**]***/
+                if (expiryASCII == NULL)
+                {
+                    result = false;
+                }
+                else
+                {
+                    double expiry;
+                    for (i = seStart; i < seStop; i++)
+                    {
+                        expiryASCII[i - seStart] = sasTokenArray[i];
+                    }
+                    expiryASCII[seStop - seStart] = '\0';
+
+                    expiry = getExpiryValue(expiryASCII);
+                    /*Codes_SRS_SASTOKEN_25_029: [**SASToken_validate shall check for expiry time from token and if token has expired then would return false **]***/
+                    if (expiry <= 0)
+                    {
+                        result = false;
+                    }
+                    else
+                    {
+                        double secSinceEpoch = get_difftime(get_time(NULL), (time_t)0);
+                        if (expiry < secSinceEpoch)
+                        {
+                            /*Codes_SRS_SASTOKEN_25_029: [**SASToken_validate shall check for expiry time from token and if token has expired then would return false **]***/
+                            result = false;
+                        }
+                        else
+                        {
+                            /*Codes_SRS_SASTOKEN_25_030: [**SASToken_validate shall return true only if the format is obeyed and the token has not yet expired **]***/
+                            result = true;
+                        }
+                    }
+                    free(expiryASCII);
+                }
+            }
+        }
+    }
+
+    return result;
+}
+
+STRING_HANDLE SASToken_Create(STRING_HANDLE key, STRING_HANDLE scope, STRING_HANDLE keyName, size_t expiry)
+{
+    STRING_HANDLE result = NULL;
+    char tokenExpirationTime[32] = { 0 };
+
+    /*Codes_SRS_SASTOKEN_06_001: [If key is NULL then SASToken_Create shall return NULL.]*/
+    /*Codes_SRS_SASTOKEN_06_003: [If scope is NULL then SASToken_Create shall return NULL.]*/
+    /*Codes_SRS_SASTOKEN_06_007: [If keyName is NULL then SASToken_Create shall return NULL.]*/
+    if ((key == NULL) ||
+        (scope == NULL) ||
+        (keyName == NULL))
+    {
+        LogError("Invalid Parameter to SASToken_Create. handle key: %p, handle scope: %p, handle keyName: %p", key, scope, keyName);
+    }
+    else
+    {
+        BUFFER_HANDLE decodedKey;
+        /*Codes_SRS_SASTOKEN_06_029: [The key parameter is decoded from base64.]*/
+        if ((decodedKey = Base64_Decoder(STRING_c_str(key))) == NULL)
+        {
+            /*Codes_SRS_SASTOKEN_06_030: [If there is an error in the decoding then SASToken_Create shall return NULL.]*/
+            LogError("Unable to decode the key for generating the SAS.");
+        }
+        else
+        {
+            /*Codes_SRS_SASTOKEN_06_026: [If the conversion to string form fails for any reason then SASToken_Create shall return NULL.]*/
+            if (size_tToString(tokenExpirationTime, sizeof(tokenExpirationTime), expiry) != 0)
+            {
+                LogError("For some reason converting seconds to a string failed.  No SAS can be generated.");
+            }
+            else
+            {
+                STRING_HANDLE toBeHashed = NULL;
+                BUFFER_HANDLE hash = NULL;
+                if (((hash = BUFFER_new()) == NULL) ||
+                    ((toBeHashed = STRING_new()) == NULL) ||
+                    ((result = STRING_new()) == NULL))
+                {
+                    LogError("Unable to allocate memory to prepare SAS token.");
+                }
+                else
+                {
+                    /*Codes_SRS_SASTOKEN_06_009: [The scope is the basis for creating a STRING_HANDLE.]*/
+                    /*Codes_SRS_SASTOKEN_06_010: [A "\n" is appended to that string.]*/
+                    /*Codes_SRS_SASTOKEN_06_011: [tokenExpirationTime is appended to that string.]*/
+                    if ((STRING_concat_with_STRING(toBeHashed, scope) != 0) ||
+                        (STRING_concat(toBeHashed, "\n") != 0) ||
+                        (STRING_concat(toBeHashed, tokenExpirationTime) != 0))
+                    {
+                        LogError("Unable to build the input to the HMAC to prepare SAS token.");
+                        STRING_delete(result);
+                        result = NULL;
+                    }
+                    else
+                    {
+                        STRING_HANDLE base64Signature = NULL;
+                        STRING_HANDLE urlEncodedSignature = NULL;
+                        size_t inLen = STRING_length(toBeHashed);
+                        const unsigned char* inBuf = (const unsigned char*)STRING_c_str(toBeHashed);
+                        size_t outLen = BUFFER_length(decodedKey);
+                        unsigned char* outBuf = BUFFER_u_char(decodedKey);
+                        /*Codes_SRS_SASTOKEN_06_013: [If an error is returned from the HMAC256 function then NULL is returned from SASToken_Create.]*/
+                        /*Codes_SRS_SASTOKEN_06_012: [An HMAC256 hash is calculated using the decodedKey, over toBeHashed.]*/
+                        /*Codes_SRS_SASTOKEN_06_014: [If there are any errors from the following operations then NULL shall be returned.]*/
+                        /*Codes_SRS_SASTOKEN_06_015: [The hash is base 64 encoded.]*/
+                        /*Codes_SRS_SASTOKEN_06_028: [base64Signature shall be url encoded.]*/
+                        /*Codes_SRS_SASTOKEN_06_016: [The string "SharedAccessSignature sr=" is the first part of the result of SASToken_Create.]*/
+                        /*Codes_SRS_SASTOKEN_06_017: [The scope parameter is appended to result.]*/
+                        /*Codes_SRS_SASTOKEN_06_018: [The string "&sig=" is appended to result.]*/
+                        /*Codes_SRS_SASTOKEN_06_019: [The string urlEncodedSignature shall be appended to result.]*/
+                        /*Codes_SRS_SASTOKEN_06_020: [The string "&se=" shall be appended to result.]*/
+                        /*Codes_SRS_SASTOKEN_06_021: [tokenExpirationTime is appended to result.]*/
+                        /*Codes_SRS_SASTOKEN_06_022: [The string "&skn=" is appended to result.]*/
+                        /*Codes_SRS_SASTOKEN_06_023: [The argument keyName is appended to result.]*/
+                        if ((HMACSHA256_ComputeHash(outBuf, outLen, inBuf, inLen, hash) != HMACSHA256_OK) ||
+                            ((base64Signature = Base64_Encode(hash)) == NULL) ||
+                            ((urlEncodedSignature = URL_Encode(base64Signature)) == NULL) ||
+                            (STRING_copy(result, "SharedAccessSignature sr=") != 0) ||
+                            (STRING_concat_with_STRING(result, scope) != 0) ||
+                            (STRING_concat(result, "&sig=") != 0) ||
+                            (STRING_concat_with_STRING(result, urlEncodedSignature) != 0) ||
+                            (STRING_concat(result, "&se=") != 0) ||
+                            (STRING_concat(result, tokenExpirationTime) != 0) ||
+                            (STRING_concat(result, "&skn=") != 0) ||
+                            (STRING_concat_with_STRING(result, keyName) != 0))
+                        {
+                            LogError("Unable to build the SAS token.");
+                            STRING_delete(result);
+                            result = NULL;
+                        }
+                        else
+                        {
+                            /* everything OK */
+                        }
+                        STRING_delete(base64Signature);
+                        STRING_delete(urlEncodedSignature);
+                    }
+                }
+                STRING_delete(toBeHashed);
+                BUFFER_delete(hash);
+            }
+            BUFFER_delete(decodedKey);
+        }
+    }
+
+    return result;
+}
+