text: // Copyright (c) Microsoft. All rights reserved.
  // Licensed under the MIT license. See LICENSE file in the project root for full license information.
  
  #include <stdlib.h>
  #include "azure_c_shared_utility/gballoc.h"
  #include "azure_c_shared_utility/macro_utils.h"
  #include "azure_c_shared_utility/umock_c_prod.h"
  #include "azure_c_shared_utility/crt_abstractions.h"
  #include "azure_c_shared_utility/agenttime.h"
  #include "azure_c_shared_utility/xlogging.h"
  #include "azure_c_shared_utility/strings.h"
  #include "azure_c_shared_utility/sastoken.h"
  #include "azure_c_shared_utility/shared_util_options.h"
  
  #ifdef USE_PROV_MODULE
  #include "azure_prov_client/internal/iothub_auth_client.h"
  #endif
  
  #include "internal/iothub_client_authorization.h"
  
  #define DEFAULT_SAS_TOKEN_EXPIRY_TIME_SECS          3600
  #define INDEFINITE_TIME                             ((time_t)(-1))
  #define MIN_SAS_EXPIRY_TIME                         5  // 5 seconds
  
  typedef struct IOTHUB_AUTHORIZATION_DATA_TAG
  {
      char* device_sas_token;
      char* device_key;
      char* device_id;
      char* module_id;
      size_t token_expiry_time_sec;
      IOTHUB_CREDENTIAL_TYPE cred_type;
  #ifdef USE_PROV_MODULE
      IOTHUB_SECURITY_HANDLE device_auth_handle;
  #endif
  } IOTHUB_AUTHORIZATION_DATA;
  
  static int get_seconds_since_epoch(size_t* seconds)
  {
      int result;
      time_t current_time;
      if ((current_time = get_time(NULL)) == INDEFINITE_TIME)
      {
          LogError("Failed getting the current local time (get_time() failed)");
          result = __FAILURE__;
      }
      else
      {
          *seconds = (size_t)get_difftime(current_time, (time_t)0);
          result = 0;
      }
      return result;
  }
  
  static IOTHUB_AUTHORIZATION_DATA* initialize_auth_client(const char* device_id, const char* module_id)
  {
      IOTHUB_AUTHORIZATION_DATA* result;
  
      /* Codes_SRS_IoTHub_Authorization_07_002: [IoTHubClient_Auth_Create shall allocate a IOTHUB_AUTHORIZATION_HANDLE that is needed for subsequent calls. ] */
      result = (IOTHUB_AUTHORIZATION_DATA*)malloc(sizeof(IOTHUB_AUTHORIZATION_DATA) );
      if (result == NULL)
      {
          /* Codes_SRS_IoTHub_Authorization_07_019: [ On error IoTHubClient_Auth_Create shall return NULL. ] */
          LogError("Failed allocating IOTHUB_AUTHORIZATION_DATA");
          result = NULL;
      }
      else
      {
          memset(result, 0, sizeof(IOTHUB_AUTHORIZATION_DATA) );
          if (mallocAndStrcpy_s(&result->device_id, device_id) != 0)
          {
              /* Codes_SRS_IoTHub_Authorization_07_019: [ On error IoTHubClient_Auth_Create shall return NULL. ] */
              LogError("Failed allocating device_key");
              free(result);
              result = NULL;
          }
          else if (module_id != NULL && mallocAndStrcpy_s(&result->module_id, module_id) != 0)
          {
              /* Codes_SRS_IoTHub_Authorization_07_019: [ On error IoTHubClient_Auth_Create shall return NULL. ] */
              LogError("Failed allocating module_id");
              free(result->device_id);
              free(result);
              result = NULL;
          }
          else
          {
              result->token_expiry_time_sec = DEFAULT_SAS_TOKEN_EXPIRY_TIME_SECS;
          }
      }
      return result;
  }
  
  IOTHUB_AUTHORIZATION_HANDLE IoTHubClient_Auth_Create(const char* device_key, const char* device_id, const char* device_sas_token, const char *module_id)
  {
      IOTHUB_AUTHORIZATION_DATA* result;
      /* Codes_SRS_IoTHub_Authorization_07_001: [if device_id is NULL IoTHubClient_Auth_Create, shall return NULL. ] */
      if (device_id == NULL)
      {
          LogError("Invalid Parameter device_id: %p", device_id);
          result = NULL;
      }
      else
      {
          result = initialize_auth_client(device_id, module_id);
          if (result == NULL)
          {
              LogError("Failure initializing auth client");
          }
          else if (device_key != NULL && mallocAndStrcpy_s(&result->device_key, device_key) != 0)
          {
              /* Codes_SRS_IoTHub_Authorization_07_019: [ On error IoTHubClient_Auth_Create shall return NULL. ] */
              LogError("Failed allocating device_key");
              free(result->device_id);
              free(result->module_id);
              free(result);
              result = NULL;
          }
          else
          {
              if (device_key != NULL)
              {
                  /* Codes_SRS_IoTHub_Authorization_07_003: [ IoTHubClient_Auth_Create shall set the credential type to IOTHUB_CREDENTIAL_TYPE_DEVICE_KEY if the device_sas_token is NULL. ]*/
                  result->cred_type = IOTHUB_CREDENTIAL_TYPE_DEVICE_KEY;
              }
              else if (device_sas_token != NULL)
              {
                  /* Codes_SRS_IoTHub_Authorization_07_020: [ else IoTHubClient_Auth_Create shall set the credential type to IOTHUB_CREDENTIAL_TYPE_SAS_TOKEN. ] */
                  result->cred_type = IOTHUB_CREDENTIAL_TYPE_SAS_TOKEN;
                  if (mallocAndStrcpy_s(&result->device_sas_token, device_sas_token) != 0)
                  {
                      /* Codes_SRS_IoTHub_Authorization_07_019: [ On error IoTHubClient_Auth_Create shall return NULL. ] */
                      LogError("Failed allocating device_key");
                      free(result->device_key);
                      free(result->device_id);
                      free(result->module_id);
                      free(result);
                      result = NULL;
                  }
              }
              else
              {
                  /* Codes_SRS_IoTHub_Authorization_07_024: [ if device_sas_token and device_key are NULL IoTHubClient_Auth_Create shall set the credential type to IOTHUB_CREDENTIAL_TYPE_UNKNOWN. ] */
                  result->cred_type = IOTHUB_CREDENTIAL_TYPE_UNKNOWN;
              }
          }
      }
      /* Codes_SRS_IoTHub_Authorization_07_004: [ If successful IoTHubClient_Auth_Create shall return a IOTHUB_AUTHORIZATION_HANDLE value. ] */
      return result;
  }
  
  IOTHUB_AUTHORIZATION_HANDLE IoTHubClient_Auth_CreateFromDeviceAuth(const char* device_id, const char* module_id)
  {
      IOTHUB_AUTHORIZATION_DATA* result;
      if (device_id == NULL)
      {
          LogError("Invalid Parameter device_id: %p", device_id);
          result = NULL;
      }
      else
      {
  #ifdef USE_PROV_MODULE
          result = initialize_auth_client(device_id, module_id);
          if (result == NULL)
          {
              LogError("Failure initializing auth client");
          }
          else
          {
              result->device_auth_handle = iothub_device_auth_create();
              if (result->device_auth_handle == NULL)
              {
                  LogError("Failed allocating IOTHUB_AUTHORIZATION_DATA");
                  free(result->device_id);
                  free(result->module_id);
                  free(result);
                  result = NULL;
              }
              else
              {
                  DEVICE_AUTH_TYPE auth_type = iothub_device_auth_get_type(result->device_auth_handle);
                  if (auth_type == AUTH_TYPE_SAS || auth_type == AUTH_TYPE_SYMM_KEY)
                  {
                      result->cred_type = IOTHUB_CREDENTIAL_TYPE_DEVICE_AUTH;
                  }
                  else
                  {
                      result->cred_type = IOTHUB_CREDENTIAL_TYPE_X509_ECC;
                  }
              }
          }
  #else
          (void)module_id;
          LogError("Failed HSM module is not supported");
          result = NULL;
  #endif
      }
      return result;
  }
  
  void IoTHubClient_Auth_Destroy(IOTHUB_AUTHORIZATION_HANDLE handle)
  {
      /* Codes_SRS_IoTHub_Authorization_07_005: [ if handle is NULL IoTHubClient_Auth_Destroy shall do nothing. ] */
      if (handle != NULL)
      {
          /* Codes_SRS_IoTHub_Authorization_07_006: [ IoTHubClient_Auth_Destroy shall free all resources associated with the IOTHUB_AUTHORIZATION_HANDLE handle. ] */
  #ifdef USE_PROV_MODULE
          iothub_device_auth_destroy(handle->device_auth_handle);
  #endif
          free(handle->device_key);
          free(handle->device_id);
          free(handle->module_id);
          free(handle->device_sas_token);
          free(handle);
      }
  }
  
  IOTHUB_CREDENTIAL_TYPE IoTHubClient_Auth_Set_x509_Type(IOTHUB_AUTHORIZATION_HANDLE handle, bool enable_x509)
  {
      IOTHUB_CREDENTIAL_TYPE result;
      if (handle != NULL)
      {
          if (enable_x509)
          {
              result = handle->cred_type = IOTHUB_CREDENTIAL_TYPE_X509;
          }
          else
          {
              if (handle->device_sas_token == NULL)
              {
                  result = handle->cred_type = IOTHUB_CREDENTIAL_TYPE_DEVICE_KEY;
              }
              else if (handle->device_key == NULL)
              {
                  result = handle->cred_type = IOTHUB_CREDENTIAL_TYPE_SAS_TOKEN;
              }
              else
              {
                  result = handle->cred_type = IOTHUB_CREDENTIAL_TYPE_UNKNOWN;
              }
          }
      }
      else
      {
          result = IOTHUB_CREDENTIAL_TYPE_UNKNOWN;
      }
      return result;
  }
  
  int IoTHubClient_Auth_Set_xio_Certificate(IOTHUB_AUTHORIZATION_HANDLE handle, XIO_HANDLE xio)
  {
      int result;
      if (handle == NULL || xio == NULL)
      {
          LogError("Invalid Parameter handle: %p xio: %p", handle, xio);
          result = __FAILURE__;
      }
      else if (handle->cred_type != IOTHUB_CREDENTIAL_TYPE_X509_ECC)
      {
          LogError("Invalid credential types for this operation");
          result = __FAILURE__;
      }
      else
      {
  #ifdef USE_PROV_MODULE
          CREDENTIAL_RESULT* cred_result = iothub_device_auth_generate_credentials(handle->device_auth_handle, NULL);
          if (cred_result == NULL)
          {
              LogError("Failure generating credentials");
              result = __FAILURE__;
          }
          else
          {
              if (xio_setoption(xio, OPTION_X509_ECC_CERT, cred_result->auth_cred_result.x509_result.x509_cert) != 0)
              {
                  LogError("Failure setting x509 cert on xio");
                  result = __FAILURE__;
              }
              else if (xio_setoption(xio, OPTION_X509_ECC_KEY, cred_result->auth_cred_result.x509_result.x509_alias_key) != 0)
              {
                  LogError("Failure setting x509 key on xio");
                  result = __FAILURE__;
              }
              else
              {
                  result = 0;
              }
              free(cred_result);
          }
  #else
          LogError("Failed HSM module is not supported");
          result = __FAILURE__;
  #endif
      }
      return result;
  }
  
  int IoTHubClient_Auth_Get_x509_info(IOTHUB_AUTHORIZATION_HANDLE handle, char** x509_cert, char** x509_key)
  {
      int result;
      if (handle == NULL || x509_cert == NULL || x509_key == NULL)
      {
          LogError("Invalid Parameter handle: %p, x509_cert: %p, x509_key: %p", handle, x509_cert, x509_key);
          result = __FAILURE__;
      }
      else if (handle->cred_type != IOTHUB_CREDENTIAL_TYPE_X509_ECC)
      {
          LogError("Invalid credential types for this operation");
          result = __FAILURE__;
      }
      else
      {
  #ifdef USE_PROV_MODULE
          CREDENTIAL_RESULT* cred_result = iothub_device_auth_generate_credentials(handle->device_auth_handle, NULL);
          if (cred_result == NULL)
          {
              LogError("Failure generating credentials");
              result = __FAILURE__;
          }
          else
          {
              if (mallocAndStrcpy_s(x509_cert, cred_result->auth_cred_result.x509_result.x509_cert) != 0)
              {
                  LogError("Failure copying certificate");
                  result = __FAILURE__;
              }
              else if (mallocAndStrcpy_s(x509_key, cred_result->auth_cred_result.x509_result.x509_alias_key) != 0)
              {
                  LogError("Failure copying private key");
                  result = __FAILURE__;
                  free(*x509_cert);
              }
              else
              {
                  result = 0;
              }
              free(cred_result);
          }
  #else
          LogError("Failed HSM module is not supported");
          result = __FAILURE__;
  #endif
      }
      return result;
  }
  
  IOTHUB_CREDENTIAL_TYPE IoTHubClient_Auth_Get_Credential_Type(IOTHUB_AUTHORIZATION_HANDLE handle)
  {
      IOTHUB_CREDENTIAL_TYPE result;
      /* Codes_SRS_IoTHub_Authorization_07_007: [ if handle is NULL IoTHub_Auth_Get_Credential_Type shall return IOTHUB_CREDENTIAL_TYPE_UNKNOWN. ] */
      if (handle == NULL)
      {
          LogError("Invalid Parameter handle: %p", handle);
          result = IOTHUB_CREDENTIAL_TYPE_UNKNOWN;
      }
      else
      {
          /* Codes_SRS_IoTHub_Authorization_07_008: [ IoTHub_Auth_Get_Credential_Type shall return the credential type that is set upon creation. ] */
          result = handle->cred_type;
      }
      return result;
  }
  
  char* IoTHubClient_Auth_Get_SasToken(IOTHUB_AUTHORIZATION_HANDLE handle, const char* scope, size_t expiry_time_relative_seconds, const char* key_name)
  {
      char* result;
      (void)expiry_time_relative_seconds;
      /* Codes_SRS_IoTHub_Authorization_07_009: [ if handle or scope are NULL, IoTHubClient_Auth_Get_SasToken shall return NULL. ] */
      if (handle == NULL)
      {
          LogError("Invalid Parameter handle: %p", handle);
          result = NULL;
      }
      else
      {
          if (handle->cred_type == IOTHUB_CREDENTIAL_TYPE_DEVICE_AUTH)
          {
  #ifdef USE_PROV_MODULE
              DEVICE_AUTH_CREDENTIAL_INFO dev_auth_cred;
              size_t sec_since_epoch;
  
              if (get_seconds_since_epoch(&sec_since_epoch) != 0)
              {
                  LogError("failure getting seconds from epoch");
                  result = NULL;
              }
              else
              {
                  memset(&dev_auth_cred, 0, sizeof(DEVICE_AUTH_CREDENTIAL_INFO));
                  size_t expiry_time = sec_since_epoch + handle->token_expiry_time_sec;
                  dev_auth_cred.sas_info.expiry_seconds = expiry_time;
                  dev_auth_cred.sas_info.token_scope = scope;
                  dev_auth_cred.sas_info.key_name = key_name;
                  dev_auth_cred.dev_auth_type = AUTH_TYPE_SAS;
  
                  CREDENTIAL_RESULT* cred_result = iothub_device_auth_generate_credentials(handle->device_auth_handle, &dev_auth_cred);
                  if (cred_result == NULL)
                  {
                      LogError("failure getting credentials from device auth module");
                      result = NULL;
                  }
                  else
                  {
                      if (mallocAndStrcpy_s(&result, cred_result->auth_cred_result.sas_result.sas_token) != 0)
                      {
                          LogError("failure allocating Sas Token");
                          result = NULL;
                      }
                      free(cred_result);
                  }
              }
  #else
              LogError("Failed HSM module is not supported");
              result = NULL;
  #endif
          }
          else if (handle->cred_type == IOTHUB_CREDENTIAL_TYPE_SAS_TOKEN)
          {
              /* Codes_SRS_IoTHub_Authorization_07_021: [If the device_sas_token is NOT NULL IoTHubClient_Auth_Get_SasToken shall return a copy of the device_sas_token. ] */
              if (handle->device_sas_token != NULL)
              {
                  if (mallocAndStrcpy_s(&result, handle->device_sas_token) != 0)
                  {
                      LogError("failure allocating sas token");
                      result = NULL;
                  }
              }
              else
              {
                  LogError("failure device sas token is NULL");
                  result = NULL;
              }
          }
          else if (handle->cred_type == IOTHUB_CREDENTIAL_TYPE_DEVICE_KEY)
          {
              /* Codes_SRS_IoTHub_Authorization_07_009: [ if handle or scope are NULL, IoTHubClient_Auth_Get_SasToken shall return NULL. ] */
              if (scope == NULL)
              {
                  LogError("Invalid Parameter scope: %p", scope);
                  result = NULL;
              }
              else
              {
                  STRING_HANDLE sas_token;
                  size_t sec_since_epoch;
  
                  /* Codes_SRS_IoTHub_Authorization_07_010: [ IoTHubClient_Auth_Get_SasToken` shall construct the expiration time using the handle->token_expiry_time_sec added to epoch time. ] */
                  if (get_seconds_since_epoch(&sec_since_epoch) != 0)
                  {
                      /* Codes_SRS_IoTHub_Authorization_07_020: [ If any error is encountered IoTHubClient_Auth_Get_ConnString shall return NULL. ] */
                      LogError("failure getting seconds from epoch");
                      result = NULL;
                  }
                  else
                  {
                      /* Codes_SRS_IoTHub_Authorization_07_011: [ IoTHubClient_Auth_Get_ConnString shall call SASToken_CreateString to construct the sas token. ] */
                      size_t expiry_time = sec_since_epoch + handle->token_expiry_time_sec;
                      if ( (sas_token = SASToken_CreateString(handle->device_key, scope, key_name, expiry_time)) == NULL)
                      {
                          /* Codes_SRS_IoTHub_Authorization_07_020: [ If any error is encountered IoTHubClient_Auth_Get_ConnString shall return NULL. ] */
                          LogError("Failed creating sas_token");
                          result = NULL;
                      }
                      else
                      {
                          /* Codes_SRS_IoTHub_Authorization_07_012: [ On success IoTHubClient_Auth_Get_ConnString shall allocate and return the sas token in a char*. ] */
                          if (mallocAndStrcpy_s(&result, STRING_c_str(sas_token) ) != 0)
                          {
                              /* Codes_SRS_IoTHub_Authorization_07_020: [ If any error is encountered IoTHubClient_Auth_Get_ConnString shall return NULL. ] */
                              LogError("Failed copying result");
                              result = NULL;
                          }
                          STRING_delete(sas_token);
                      }
                  }
              }
          }
          else
          {
              LogError("Failed getting sas token invalid credential type");
              result = NULL;
          }
      }
      return result;
  }
  
  const char* IoTHubClient_Auth_Get_DeviceId(IOTHUB_AUTHORIZATION_HANDLE handle)
  {
      const char* result;
      if (handle == NULL)
      {
          /* Codes_SRS_IoTHub_Authorization_07_013: [ if handle is NULL, IoTHubClient_Auth_Get_DeviceId shall return NULL. ] */
          LogError("Invalid Parameter handle: %p", handle);
          result = NULL;
      }
      else
      {
          /* Codes_SRS_IoTHub_Authorization_07_014: [ IoTHubClient_Auth_Get_DeviceId shall return the device_id specified upon creation. ] */
          result = handle->device_id;
      }
      return result;
  }
  
  const char* IoTHubClient_Auth_Get_ModuleId(IOTHUB_AUTHORIZATION_HANDLE handle)
  {
      const char* result;
      if (handle == NULL)
      {
          /* Codes_SRS_IoTHub_Authorization_31_025: [ if handle is NULL, IoTHubClient_Auth_Get_ModuleId shall return NULL. ] */
          LogError("Invalid Parameter handle: %p", handle);
          result = NULL;
      }
      else
      {
          /* Codes_SRS_IoTHub_Authorization_31_026: [ IoTHubClient_Auth_Get_ModuleId shall return the module_id specified upon creation. ] */
          result = handle->module_id;
      }
      return result;
  }
  
  const char* IoTHubClient_Auth_Get_DeviceKey(IOTHUB_AUTHORIZATION_HANDLE handle)
  {
      const char* result;
      if (handle == NULL)
      {
          /* Codes_SRS_IoTHub_Authorization_07_022: [ if handle is NULL, IoTHubClient_Auth_Get_DeviceKey shall return NULL. ] */
          LogError("Invalid Parameter handle: %p", handle);
          result = NULL;
      }
      else
      {
          /* Codes_SRS_IoTHub_Authorization_07_023: [ IoTHubClient_Auth_Get_DeviceKey shall return the device_key specified upon creation. ] */
          result = handle->device_key;
      }
      return result;
  }
  
  SAS_TOKEN_STATUS IoTHubClient_Auth_Is_SasToken_Valid(IOTHUB_AUTHORIZATION_HANDLE handle)
  {
      SAS_TOKEN_STATUS result;
      if (handle == NULL)
      {
          /* Codes_SRS_IoTHub_Authorization_07_015: [ if handle is NULL, IoTHubClient_Auth_Is_SasToken_Valid shall return false. ] */
          LogError("Invalid Parameter handle: %p", handle);
          result = SAS_TOKEN_STATUS_FAILED;
      }
      else
      {
          if (handle->cred_type == IOTHUB_CREDENTIAL_TYPE_SAS_TOKEN)
          {
              if (handle->device_sas_token == NULL)
              {
                  /* Codes_SRS_IoTHub_Authorization_07_017: [ If the sas_token is NULL IoTHubClient_Auth_Is_SasToken_Valid shall return false. ] */
                  LogError("Failure: device_sas_toke is NULL");
                  result = SAS_TOKEN_STATUS_FAILED;
              }
              else
              {
                  /* Codes_SRS_IoTHub_Authorization_07_018: [ otherwise IoTHubClient_Auth_Is_SasToken_Valid shall return the value returned by SASToken_Validate. ] */
                  STRING_HANDLE strSasToken = STRING_construct(handle->device_sas_token);
                  if (strSasToken != NULL)
                  {
                      if (!SASToken_Validate(strSasToken))
                      {
                          result = SAS_TOKEN_STATUS_INVALID;
                      }
                      else
                      {
                          result = SAS_TOKEN_STATUS_VALID;
                      }
                      STRING_delete(strSasToken);
                  }
                  else
                  {
                      LogError("Failure constructing SAS Token");
                      result = SAS_TOKEN_STATUS_FAILED;
                  }
              }
          }
          else
          {
              /* Codes_SRS_IoTHub_Authorization_07_016: [ if credential type is not IOTHUB_CREDENTIAL_TYPE_SAS_TOKEN IoTHubClient_Auth_Is_SasToken_Valid shall return SAS_TOKEN_STATUS_VALID. ] */
              result = SAS_TOKEN_STATUS_VALID;
          }
      }
      return result;
  }
  
  #ifdef USE_EDGE_MODULES
  
  // For debugging C modules, the environment can set the environment variable 'EdgeModuleCACertificateFile' to provide
  // trusted certificates.  We'd otherwise usually get these from trusted Edge service, but this complicates debugging experience.
  // EdgeModuleCACertificateFile and the related EdgeHubConnectionString can be set either manually or by tooling (e.g. VS Code).
  static char* read_ca_certificate_from_file(const char* certificate_file_name)
  {
      char* result;
      FILE *file_stream = NULL;
  
      if ((file_stream = fopen(certificate_file_name, "r")) == NULL)
      {
          LogError("Cannot read file %s, errno=%d", certificate_file_name, errno);
          result = NULL;
      }
      else if (fseek(file_stream, 0, SEEK_END) != 0)
      {
          LogError("fseek on file %s fails, errno=%d", certificate_file_name, errno);
          result = NULL;
      }
      else
      {
          long int file_size = ftell(file_stream);
          if (file_size < 0)
          {
              LogError("ftell fails reading %s, errno=%d",  certificate_file_name, errno);
              result = NULL;
          }
          else if (file_size == 0)
          {
              LogError("file %s is 0 bytes, which is not valid certificate",  certificate_file_name);
              result = NULL;
          }
          else
          {
              rewind(file_stream);
  
              if ((result = calloc(1, file_size + 1)) == NULL)
              {
                  LogError("Cannot allocate %lu bytes", (unsigned long)file_size);
              }
              else if ((fread(result, 1, file_size, file_stream) == 0) || (ferror(file_stream) != 0))
              {
                  LogError("fread failed on file %s, errno=%d", certificate_file_name, errno);
                  free(result);
                  result = NULL;
              }
          }
      }
  
      if (file_stream != NULL)
      {
          fclose(file_stream);
      }
  
      return result;
  }
  
  // IoTHubClient_Auth_Get_TrustBundle retrieves a trust bundle - namely a PEM indicating the certificates the client should
  // trust as root authorities - to caller.  If certificate_file_name, we read this from a local file.  This should in general
  // be limited only to debugging modules on Edge.  If certificate_file_name is NULL, we invoke into the underlying
  // HSM to retrieve this.
  char* IoTHubClient_Auth_Get_TrustBundle(IOTHUB_AUTHORIZATION_HANDLE handle, const char* certificate_file_name)
  {
      char* result;
      if (handle == NULL)
      {
          LogError("Security Handle is NULL");
          result = NULL;
      }
      else if (certificate_file_name != NULL)
      {
          result = read_ca_certificate_from_file(certificate_file_name);
      }
      else
      {
          result = iothub_device_auth_get_trust_bundle(handle->device_auth_handle);
      }
      return result;
  }
  #endif
  
  int IoTHubClient_Auth_Set_SasToken_Expiry(IOTHUB_AUTHORIZATION_HANDLE handle, size_t expiry_time_seconds)
  {
      int result;
      if (handle == NULL)
      {
          LogError("Invalid handle value handle: NULL");
          result = __FAILURE__;
      }
      // Validate the expiry_time in seconds
      else if (expiry_time_seconds < MIN_SAS_EXPIRY_TIME)
      {
          LogError("Failure setting expiry time to value %lu min value is %d", (unsigned long)expiry_time_seconds, MIN_SAS_EXPIRY_TIME);
          result = __FAILURE__;
      }
      else
      {
          handle->token_expiry_time_sec = expiry_time_seconds;
          result = 0;
      }
      return result;
  }
  
  size_t IoTHubClient_Auth_Get_SasToken_Expiry(IOTHUB_AUTHORIZATION_HANDLE handle)
  {
      size_t result;
      if (handle == NULL)
      {
          LogError("Invalid handle value handle: NULL");
          result = 0;
      }
      else
      {
          result = handle->token_expiry_time_sec;
      }
      return result;
  }
  