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>
  #ifdef _CRTDBG_MAP_ALLOC
  #include <crtdbg.h>
  #endif
  
  #include <stdio.h>
  #include <ctype.h>
  #include "azure_c_shared_utility/gballoc.h"
  #include "azure_c_shared_utility/httpheaders.h"
  #include "azure_c_shared_utility/crt_abstractions.h"
  #include "azure_c_shared_utility/xlogging.h"
  #include "azure_c_shared_utility/xio.h"
  #include "azure_c_shared_utility/platform.h"
  #include "azure_c_shared_utility/tlsio.h"
  #include "azure_c_shared_utility/threadapi.h"
  #include "azure_c_shared_utility/shared_util_options.h"
  #include <string.h>
  #include <limits.h>
  
  /*Codes_SRS_HTTPAPI_COMPACT_21_001: [ The httpapi_compact shall implement the methods defined by the `httpapi.h`. ]*/
  /*Codes_SRS_HTTPAPI_COMPACT_21_002: [ The httpapi_compact shall support the http requests. ]*/
  /*Codes_SRS_HTTPAPI_COMPACT_21_003: [ The httpapi_compact shall return error codes defined by HTTPAPI_RESULT. ]*/
  #include "azure_c_shared_utility/httpapi.h"
  
  #define MAX_HOSTNAME     64
  #define TEMP_BUFFER_SIZE 1024
  
  /*Codes_SRS_HTTPAPI_COMPACT_21_077: [ The HTTPAPI_ExecuteRequest shall wait, at least, 10 seconds for the SSL open process. ]*/
  #define MAX_OPEN_RETRY   100
  /*Codes_SRS_HTTPAPI_COMPACT_21_084: [ The HTTPAPI_CloseConnection shall wait, at least, 10 seconds for the SSL close process. ]*/
  #define MAX_CLOSE_RETRY   100
  /*Codes_SRS_HTTPAPI_COMPACT_21_079: [ The HTTPAPI_ExecuteRequest shall wait, at least, 20 seconds to send a buffer using the SSL connection. ]*/
  #define MAX_SEND_RETRY   200
  /*Codes_SRS_HTTPAPI_COMPACT_21_081: [ The HTTPAPI_ExecuteRequest shall try to read the message with the response up to 20 seconds. ]*/
  #define MAX_RECEIVE_RETRY   200
  /*Codes_SRS_HTTPAPI_COMPACT_21_083: [ The HTTPAPI_ExecuteRequest shall wait, at least, 100 milliseconds between retries. ]*/
  #define RETRY_INTERVAL_IN_MICROSECONDS  100
  
  DEFINE_ENUM_STRINGS(HTTPAPI_RESULT, HTTPAPI_RESULT_VALUES)
  
  typedef struct HTTP_HANDLE_DATA_TAG
  {
      char*           certificate;
      char*           x509ClientCertificate;
      char*           x509ClientPrivateKey;
      XIO_HANDLE      xio_handle;
      size_t          received_bytes_count;
      unsigned char*  received_bytes;
      unsigned int    is_io_error : 1;
      unsigned int    is_connected : 1;
      unsigned int    send_completed : 1;
  } HTTP_HANDLE_DATA;
  
  /*the following function does the same as sscanf(pos2, "%d", &sec)*/
  /*this function only exists because some of platforms do not have sscanf. */
  static int ParseStringToDecimal(const char *src, int* dst)
  {
      int result;
      char* next;
      (*dst) = strtol(src, &next, 0);
      if ((src == next) || ((((*dst) == LONG_MAX) || ((*dst) == LONG_MIN)) && (errno != 0)))
      {
          result = EOF;
      }
      else
      {
          result = 1;
      }
      return result;
  }
  
  /*the following function does the same as sscanf(pos2, "%x", &sec)*/
  /*this function only exists because some of platforms do not have sscanf. This is not a full implementation; it only works with well-defined x numbers. */
  #define HEXA_DIGIT_VAL(c)         (((c>='0') && (c<='9')) ? (c-'0') : ((c>='a') && (c<='f')) ? (c-'a'+10) : ((c>='A') && (c<='F')) ? (c-'A'+10) : -1)
  static int ParseStringToHexadecimal(const char *src, size_t* dst)
  {
      int result;
      int digitVal;
      if (src == NULL)
      {
          result = EOF;
      }
      else if (HEXA_DIGIT_VAL(*src) == -1)
      {
          result = EOF;
      }
      else
      {
          (*dst) = 0;
          while ((digitVal = HEXA_DIGIT_VAL(*src)) != -1)
          {
              (*dst) *= 0x10;
              (*dst) += (size_t)digitVal;
              src++;
          }
          result = 1;
      }
      return result;
  }
  
  /*the following function does the same as sscanf(buf, "HTTP/%*d.%*d %d %*[^\r\n]", &ret) */
  /*this function only exists because some of platforms do not have sscanf. This is not a full implementation; it only works with well-defined HTTP response. */
  static int  ParseHttpResponse(const char* src, int* dst)
  {
      int result;
      static const char HTTPPrefix[] = "HTTP/";
      bool fail;
      const char* runPrefix;
  
      if ((src == NULL) || (dst == NULL))
      {
          result = EOF;
      }
      else
      {
          fail = false;
          runPrefix = HTTPPrefix;
  
          while((*runPrefix) != '\0')
          {
              if ((*runPrefix) != (*src))
              {
                  fail = true;
                  break;
              }
              src++;
              runPrefix++;
          }
  
          if (!fail)
          {
              while ((*src) != '.')
              {
                  if ((*src) == '\0')
                  {
                      fail = true;
                      break;
                  }
                  src++;
              }
          }
  
          if (!fail)
          {
              while ((*src) != ' ')
              {
                  if ((*src) == '\0')
                  {
                      fail = true;
                      break;
                  }
                  src++;
              }
          }
  
          if (fail)
          {
              result = EOF;
          }
          else
          {
              result = ParseStringToDecimal(src, dst);
          }
      }
  
      return result;
  }
  
  HTTPAPI_RESULT HTTPAPI_Init(void)
  {
  /*Codes_SRS_HTTPAPI_COMPACT_21_004: [ The HTTPAPI_Init shall allocate all memory to control the http protocol. ]*/
  /*Codes_SRS_HTTPAPI_COMPACT_21_007: [ If there is not enough memory to control the http protocol, the HTTPAPI_Init shall return HTTPAPI_ALLOC_FAILED. ]*/
  /**
   * No memory is necessary.
   */
  
   /*Codes_SRS_HTTPAPI_COMPACT_21_006: [ If HTTPAPI_Init succeed allocating all the needed memory, it shall return HTTPAPI_OK. ]*/
  return HTTPAPI_OK;
  }
  
  void HTTPAPI_Deinit(void)
  {
      /*Codes_SRS_HTTPAPI_COMPACT_21_009: [ The HTTPAPI_Init shall release all memory allocated by the httpapi_compact. ]*/
      /**
      * No memory was necessary.
      */
  }
  
  /*Codes_SRS_HTTPAPI_COMPACT_21_011: [ The HTTPAPI_CreateConnection shall create an http connection to the host specified by the hostName parameter. ]*/
  HTTP_HANDLE HTTPAPI_CreateConnection(const char* hostName)
  {
      HTTP_HANDLE_DATA* http_instance;
      TLSIO_CONFIG tlsio_config;
  
      if (hostName == NULL)
      {
          /*Codes_SRS_HTTPAPI_COMPACT_21_014: [ If the hostName is NULL, the HTTPAPI_CreateConnection shall return NULL as the handle. ]*/
          LogError("Invalid host name. Null hostName parameter.");
          http_instance = NULL;
      }
      else if (*hostName == '\0')
      {
          /*Codes_SRS_HTTPAPI_COMPACT_21_015: [ If the hostName is empty, the HTTPAPI_CreateConnection shall return NULL as the handle. ]*/
          LogError("Invalid host name. Empty string.");
          http_instance = NULL;
      }
      else
      {
          http_instance = (HTTP_HANDLE_DATA*)malloc(sizeof(HTTP_HANDLE_DATA));
          /*Codes_SRS_HTTPAPI_COMPACT_21_013: [ If there is not enough memory to control the http connection, the HTTPAPI_CreateConnection shall return NULL as the handle. ]*/
          if (http_instance == NULL)
          {
              LogError("There is no memory to control the http connection");
          }
          else
          {
              tlsio_config.hostname = hostName;
              tlsio_config.port = 443;
  
              http_instance->xio_handle = xio_create(platform_get_default_tlsio(), (void*)&tlsio_config);
  
              /*Codes_SRS_HTTPAPI_COMPACT_21_016: [ If the HTTPAPI_CreateConnection failed to create the connection, it shall return NULL as the handle. ]*/
              if (http_instance->xio_handle == NULL)
              {
                  LogError("Create connection failed");
                  free(http_instance);
                  http_instance = NULL;
              }
              else
              {
                  http_instance->is_connected = 0;
                  http_instance->is_io_error = 0;
                  http_instance->received_bytes_count = 0;
                  http_instance->received_bytes = NULL;
                  http_instance->certificate = NULL;
                  http_instance->x509ClientCertificate = NULL;
                  http_instance->x509ClientPrivateKey = NULL;
              }
          }
      }
  
      /*Codes_SRS_HTTPAPI_COMPACT_21_012: [ The HTTPAPI_CreateConnection shall return a non-NULL handle on success. ]*/
      return (HTTP_HANDLE)http_instance;
  }
  
  static void on_io_close_complete(void* context)
  {
      HTTP_HANDLE_DATA* http_instance = (HTTP_HANDLE_DATA*)context;
  
      if (http_instance != NULL)
      {
          http_instance->is_connected = 0;
      }
  }
  
  void HTTPAPI_CloseConnection(HTTP_HANDLE handle)
  {
      HTTP_HANDLE_DATA* http_instance = (HTTP_HANDLE_DATA*)handle;
  
      /*Codes_SRS_HTTPAPI_COMPACT_21_020: [ If the connection handle is NULL, the HTTPAPI_CloseConnection shall not do anything. ]*/
      if (http_instance != NULL)
      {
          /*Codes_SRS_HTTPAPI_COMPACT_21_019: [ If there is no previous connection, the HTTPAPI_CloseConnection shall not do anything. ]*/
          if (http_instance->xio_handle != NULL)
          {
              http_instance->is_io_error = 0;
              /*Codes_SRS_HTTPAPI_COMPACT_21_017: [ The HTTPAPI_CloseConnection shall close the connection previously created in HTTPAPI_ExecuteRequest. ]*/
              if (xio_close(http_instance->xio_handle, on_io_close_complete, http_instance) != 0)
              {
                  LogError("The SSL got error closing the connection");
                  /*Codes_SRS_HTTPAPI_COMPACT_21_087: [ If the xio return anything different than 0, the HTTPAPI_CloseConnection shall destroy the connection anyway. ]*/
                  http_instance->is_connected = 0;
              }
              else
              {
                  /*Codes_SRS_HTTPAPI_COMPACT_21_084: [ The HTTPAPI_CloseConnection shall wait, at least, 10 seconds for the SSL close process. ]*/
                  int countRetry = MAX_CLOSE_RETRY;
                  while (http_instance->is_connected == 1)
                  {
                      xio_dowork(http_instance->xio_handle);
                      if ((countRetry--) < 0)
                      {
                          /*Codes_SRS_HTTPAPI_COMPACT_21_085: [ If the HTTPAPI_CloseConnection retries 10 seconds to close the connection without success, it shall destroy the connection anyway. ]*/
                          LogError("Close timeout. The SSL didn't close the connection");
                          http_instance->is_connected = 0;
                      }
                      else if (http_instance->is_io_error == 1)
                      {
                          LogError("The SSL got error closing the connection");
                          http_instance->is_connected = 0;
                      }
                      else if (http_instance->is_connected == 1)
                      {
                          LogInfo("Waiting for TLS close connection");
                          /*Codes_SRS_HTTPAPI_COMPACT_21_086: [ The HTTPAPI_CloseConnection shall wait, at least, 100 milliseconds between retries. ]*/
                          ThreadAPI_Sleep(RETRY_INTERVAL_IN_MICROSECONDS);
                      }
                  }
              }
              /*Codes_SRS_HTTPAPI_COMPACT_21_076: [ After close the connection, The HTTPAPI_CloseConnection shall destroy the connection previously created in HTTPAPI_CreateConnection. ]*/
              xio_destroy(http_instance->xio_handle);
          }
  
          /*Codes_SRS_HTTPAPI_COMPACT_21_018: [ If there is a certificate associated to this connection, the HTTPAPI_CloseConnection shall free all allocated memory for the certificate. ]*/
          if (http_instance->certificate)
          {
              free(http_instance->certificate);
          }
  
          /*Codes_SRS_HTTPAPI_COMPACT_06_001: [ If there is a x509 client certificate associated to this connection, the HTTAPI_CloseConnection shall free all allocated memory for the certificate. ]*/
          if (http_instance->x509ClientCertificate)
          {
              free(http_instance->x509ClientCertificate);
          }
  
          /*Codes_SRS_HTTPAPI_COMPACT_06_002: [ If there is a x509 client private key associated to this connection, then HTTP_CloseConnection shall free all the allocated memory for the private key. ]*/
          if (http_instance->x509ClientPrivateKey)
          {
              free(http_instance->x509ClientPrivateKey);
          }
          free(http_instance);
      }
  }
  
  static void on_io_open_complete(void* context, IO_OPEN_RESULT open_result)
  {
      HTTP_HANDLE_DATA* http_instance = (HTTP_HANDLE_DATA*)context;
  
      if (http_instance != NULL)
      {
          if (open_result == IO_OPEN_OK)
          {
              http_instance->is_connected = 1;
              http_instance->is_io_error = 0;
          }
          else
          {
              http_instance->is_io_error = 1;
          }
      }
  }
  
  static void on_send_complete(void* context, IO_SEND_RESULT send_result)
  {
      HTTP_HANDLE_DATA* http_instance = (HTTP_HANDLE_DATA*)context;
  
      if (http_instance != NULL)
      {
          if (send_result == IO_SEND_OK)
          {
              http_instance->send_completed = 1;
              http_instance->is_io_error = 0;
          }
          else
          {
              http_instance->is_io_error = 1;
          }
      }
  }
  
  #define TOLOWER(c) (((c>='A') && (c<='Z'))?c-'A'+'a':c)
  static int InternStrnicmp(const char* s1, const char* s2, size_t n)
  {
      int result;
  
      if ((s1 == NULL) || (s2 == NULL))
      {
          result = -1;
      }
      else
      {
          result = 0;
          while (((n--) >= 0) && ((*s1) != '\0') && ((*s2) != '\0') && (result == 0))
          {
              /* compute the difference between the chars */
              result = TOLOWER(*s1) - TOLOWER(*s2);
              s1++;
              s2++;
          }
  
          if ((*s2) != '\0')
          {
              result = -1;
          }
      }
  
      return result;
  }
  
  static void on_bytes_received(void* context, const unsigned char* buffer, size_t size)
  {
      unsigned char* new_received_bytes;
      HTTP_HANDLE_DATA* http_instance = (HTTP_HANDLE_DATA*)context;
  
      if (http_instance != NULL)
      {
  
          if (buffer == NULL)
          {
              http_instance->is_io_error = 1;
              LogError("NULL pointer error");
          }
          else
          {
              /* Here we got some bytes so we'll buffer them so the receive functions can consumer it */
              new_received_bytes = (unsigned char*)realloc(http_instance->received_bytes, http_instance->received_bytes_count + size);
              if (new_received_bytes == NULL)
              {
                  http_instance->is_io_error = 1;
                  LogError("Error allocating memory for received data");
              }
              else
              {
                  http_instance->received_bytes = new_received_bytes;
                  if (memcpy(http_instance->received_bytes + http_instance->received_bytes_count, buffer, size) == NULL)
                  {
                      http_instance->is_io_error = 1;
                      LogError("Error copping received data to the HTTP bufffer");
                  }
                  else
                  {
                      http_instance->received_bytes_count += size;
                  }
              }
          }
      }
  }
  
  static void on_io_error(void* context)
  {
      HTTP_HANDLE_DATA* http_instance = (HTTP_HANDLE_DATA*)context;
      if (http_instance != NULL)
      {
          http_instance->is_io_error = 1;
          LogError("Error signalled by underlying IO");
      }
  }
  
  static int conn_receive(HTTP_HANDLE_DATA* http_instance, char* buffer, int count)
  {
      int result;
  
      if ((http_instance == NULL) || (buffer == NULL) || (count < 0))
      {
          LogError("conn_receive: %s", ((http_instance == NULL) ? "Invalid HTTP instance" : "Invalid HTTP buffer"));
          result = -1;
      }
      else
      {
          result = 0;
          while (result < count)
          {
              xio_dowork(http_instance->xio_handle);
  
              /* if any error was detected while receiving then simply break and report it */
              if (http_instance->is_io_error != 0)
              {
                  LogError("xio reported error on dowork");
                  result = -1;
                  break;
              }
  
              if (http_instance->received_bytes_count >= (size_t)count)
              {
                  /* Consuming bytes from the receive buffer */
                  (void)memcpy(buffer, http_instance->received_bytes, count);
                  (void)memmove(http_instance->received_bytes, http_instance->received_bytes + count, http_instance->received_bytes_count - count);
                  http_instance->received_bytes_count -= count;
  
                  /* we're not reallocating at each consumption so that we don't trash due to byte by byte consumption */
                  if (http_instance->received_bytes_count == 0)
                  {
                      free(http_instance->received_bytes);
                      http_instance->received_bytes = NULL;
                  }
  
                  result = count;
                  break;
              }
  
              /*Codes_SRS_HTTPAPI_COMPACT_21_083: [ The HTTPAPI_ExecuteRequest shall wait, at least, 100 milliseconds between retries. ]*/
              ThreadAPI_Sleep(RETRY_INTERVAL_IN_MICROSECONDS);
          }
      }
  
      return result;
  }
  
  static void conn_receive_discard_buffer(HTTP_HANDLE_DATA* http_instance)
  {
      if (http_instance != NULL)
      {
          if (http_instance->received_bytes != NULL)
          {
              free(http_instance->received_bytes);
              http_instance->received_bytes = NULL;
          }
          http_instance->received_bytes_count = 0;
      }
  }
  
  static int readLine(HTTP_HANDLE_DATA* http_instance, char* buf, const size_t maxBufSize)
  {
      int resultLineSize;
  
      if ((http_instance == NULL) || (buf == NULL) || (maxBufSize < 0))
      {
          LogError("%s", ((http_instance == NULL) ? "Invalid HTTP instance" : "Invalid HTTP buffer"));
          resultLineSize = -1;
      }
      else
      {
          char* destByte = buf;
          /*Codes_SRS_HTTPAPI_COMPACT_21_081: [ The HTTPAPI_ExecuteRequest shall try to read the message with the response up to 20 seconds. ]*/
          int countRetry = MAX_RECEIVE_RETRY;
          bool endOfSearch = false;
          resultLineSize = -1;
          while (!endOfSearch)
          {
              xio_dowork(http_instance->xio_handle);
  
              /* if any error was detected while receiving then simply break and report it */
              if (http_instance->is_io_error != 0)
              {
                  LogError("xio reported error on dowork");
                  endOfSearch = true;
              }
              else
              {
                  unsigned char* receivedByte = http_instance->received_bytes;
                  while (receivedByte < (http_instance->received_bytes + http_instance->received_bytes_count))
                  {
                      if ((*receivedByte) != '\r')
                      {
                          (*destByte) = (*receivedByte);
                          destByte++;
                          receivedByte++;
  
                          if (destByte >= (buf + maxBufSize - 1))
                          {
                              LogError("Received message is bigger than the http buffer");
                              receivedByte = http_instance->received_bytes + http_instance->received_bytes_count;
                              endOfSearch = true;
                              break;
                          }
                      }
                      else
                      {
                          receivedByte++;
                          if ((receivedByte < (http_instance->received_bytes + http_instance->received_bytes_count)) && ((*receivedByte) == '\n'))
                          {
                              receivedByte++;
                          }
                          (*destByte) = '\0';
                          resultLineSize = (int)(destByte - buf);
                          endOfSearch = true;
                          break;
                      }
                  }
  
                  http_instance->received_bytes_count -= (receivedByte - http_instance->received_bytes);
                  if (http_instance->received_bytes_count != 0)
                  {
                      (void)memmove(http_instance->received_bytes, receivedByte, http_instance->received_bytes_count);
                  }
                  else
                  {
                      conn_receive_discard_buffer(http_instance);
                  }
              }
  
              if (!endOfSearch)
              {
                  if ((countRetry--) > 0)
                  {
                      /*Codes_SRS_HTTPAPI_COMPACT_21_083: [ The HTTPAPI_ExecuteRequest shall wait, at least, 100 milliseconds between retries. ]*/
                      ThreadAPI_Sleep(RETRY_INTERVAL_IN_MICROSECONDS);
                  }
                  else
                  {
                      /*Codes_SRS_HTTPAPI_COMPACT_21_082: [ If the HTTPAPI_ExecuteRequest retries 20 seconds to receive the message without success, it shall fail and return HTTPAPI_READ_DATA_FAILED. ]*/
                      LogError("Receive timeout. The HTTP request is incomplete");
                      endOfSearch = true;
                  }
              }
          }
      }
  
      return resultLineSize;
  }
  
  static int readChunk(HTTP_HANDLE_DATA* http_instance, char* buf, size_t size)
  {
      int cur, offset;
  
      // read content with specified length, even if it is received
      // only in chunks due to fragmentation in the networking layer.
      // returns -1 in case of error.
      offset = 0;
      while (size > (size_t)0)
      {
          cur = conn_receive(http_instance, buf + offset, (int)size);
  
          // end of stream reached
          if (cur == 0)
          {
              break;
          }
  
          // read cur bytes (might be less than requested)
          size -= (size_t)cur;
          offset += cur;
      }
  
      return offset;
  }
  
  static int skipN(HTTP_HANDLE_DATA* http_instance, size_t n)
  {
      // read and abandon response content with specified length
      // returns -1 in case of error.
  
      int result;
  
      if (http_instance == NULL)
      {
          LogError("Invalid HTTP instance");
          result = -1;
      }
      else
      {
          /*Codes_SRS_HTTPAPI_COMPACT_21_081: [ The HTTPAPI_ExecuteRequest shall try to read the message with the response up to 20 seconds. ]*/
          int countRetry = MAX_RECEIVE_RETRY;
          result = (int)n;
          while (n > 0)
          {
              xio_dowork(http_instance->xio_handle);
  
              /* if any error was detected while receiving then simply break and report it */
              if (http_instance->is_io_error != 0)
              {
                  LogError("xio reported error on dowork");
                  result = -1;
                  n = 0;
              }
              else
              {
                  if (http_instance->received_bytes_count <= n)
                  {
                      n -= http_instance->received_bytes_count;
                      http_instance->received_bytes_count = 0;
                  }
                  else
                  {
                      http_instance->received_bytes_count -= n;
                      (void)memmove(http_instance->received_bytes, http_instance->received_bytes + n, http_instance->received_bytes_count);
                      n = 0;
                  }
  
                  if (n > 0)
                  {
                      if ((countRetry--) > 0)
                      {
                          /*Codes_SRS_HTTPAPI_COMPACT_21_083: [ The HTTPAPI_ExecuteRequest shall wait, at least, 100 milliseconds between retries. ]*/
                          ThreadAPI_Sleep(RETRY_INTERVAL_IN_MICROSECONDS);
                      }
                      else
                      {
                          /*Codes_SRS_HTTPAPI_COMPACT_21_082: [ If the HTTPAPI_ExecuteRequest retries 20 seconds to receive the message without success, it shall fail and return HTTPAPI_READ_DATA_FAILED. ]*/
                          LogError("Receive timeout. The HTTP request is incomplete");
                          n = 0;
                          result = -1;
                      }
                  }
              }
          }
      }
  
      return result;
  }
  
  
  /*Codes_SRS_HTTPAPI_COMPACT_21_021: [ The HTTPAPI_ExecuteRequest shall execute the http communtication with the provided host, sending a request and reciving the response. ]*/
  static HTTPAPI_RESULT OpenXIOConnection(HTTP_HANDLE_DATA* http_instance)
  {
      HTTPAPI_RESULT result;
  
      if (http_instance->is_connected != 0)
      {
          /*Codes_SRS_HTTPAPI_COMPACT_21_033: [ If the whole process succeed, the HTTPAPI_ExecuteRequest shall retur HTTPAPI_OK. ]*/
          result = HTTPAPI_OK;
      }
      else
      {
          http_instance->is_io_error = 0;
  
          /*Codes_SRS_HTTPAPI_COMPACT_21_022: [ If a Certificate was provided, the HTTPAPI_ExecuteRequest shall set this option on the transport layer. ]*/
          if ((http_instance->certificate != NULL) &&
              (xio_setoption(http_instance->xio_handle, "TrustedCerts", http_instance->certificate) != 0))
          {
              /*Codes_SRS_HTTPAPI_COMPACT_21_023: [ If the transport failed setting the Certificate, the HTTPAPI_ExecuteRequest shall not send any request and return HTTPAPI_SET_OPTION_FAILED. ]*/
              result = HTTPAPI_SET_OPTION_FAILED;
              LogInfo("Could not load certificate");
          }
          /*Codes_SRS_HTTPAPI_COMPACT_06_003: [ If the x509 client certificate is provided, the HTTPAPI_ExecuteRequest shall set this option on the transport layer. ]*/
          else if ((http_instance->x509ClientCertificate != NULL) &&
              (xio_setoption(http_instance->xio_handle, SU_OPTION_X509_CERT, http_instance->x509ClientCertificate) != 0))
          {
              /*Codes_SRS_HTTPAPI_COMPACT_06_005: [ If the transport failed setting the client certificate, the HTTPAPI_ExecuteRequest shall not send any request and return HTTPAPI_SET_OPTION_FAILED. ]*/
              result = HTTPAPI_SET_OPTION_FAILED;
              LogInfo("Could not load the client certificate");
          }
          else if ((http_instance->x509ClientPrivateKey != NULL) &&
              (xio_setoption(http_instance->xio_handle, SU_OPTION_X509_PRIVATE_KEY, http_instance->x509ClientPrivateKey) != 0))
          {
  
              /*Codes_SRS_HTTPAPI_COMPACT_06_006: [ If the transport failed setting the client certificate private key, the HTTPAPI_ExecuteRequest shall not send any request and return HTTPAPI_SET_OPTION_FAILED. ] */
              result = HTTPAPI_SET_OPTION_FAILED;
              LogInfo("Could not load the client certificate private key");
          }
          else
          {
              /*Codes_SRS_HTTPAPI_COMPACT_21_024: [ The HTTPAPI_ExecuteRequest shall open the transport connection with the host to send the request. ]*/
              if (xio_open(http_instance->xio_handle, on_io_open_complete, http_instance, on_bytes_received, http_instance, on_io_error, http_instance) != 0)
              {
                  /*Codes_SRS_HTTPAPI_COMPACT_21_025: [ If the open process failed, the HTTPAPI_ExecuteRequest shall not send any request and return HTTPAPI_OPEN_REQUEST_FAILED. ]*/
                  result = HTTPAPI_OPEN_REQUEST_FAILED;
              }
              else
              {
                  /*Codes_SRS_HTTPAPI_COMPACT_21_033: [ If the whole process succeed, the HTTPAPI_ExecuteRequest shall retur HTTPAPI_OK. ]*/
                  result = HTTPAPI_OK;
                  /*Codes_SRS_HTTPAPI_COMPACT_21_077: [ The HTTPAPI_ExecuteRequest shall wait, at least, 10 seconds for the SSL open process. ]*/
                  int countRetry = MAX_OPEN_RETRY;
                  while ((http_instance->is_connected == 0) &&
                      (http_instance->is_io_error == 0))
                  {
                      xio_dowork(http_instance->xio_handle);
                      LogInfo("Waiting for TLS connection");
                      if ((countRetry--) < 0)
                      {
                          /*Codes_SRS_HTTPAPI_COMPACT_21_078: [ If the HTTPAPI_ExecuteRequest cannot open the connection in 10 seconds, it shall fail and return HTTPAPI_OPEN_REQUEST_FAILED. ]*/
                          LogError("Open timeout. The HTTP request is incomplete");
                          result = HTTPAPI_OPEN_REQUEST_FAILED;
                          break;
                      }
                      else
                      {
                          /*Codes_SRS_HTTPAPI_COMPACT_21_083: [ The HTTPAPI_ExecuteRequest shall wait, at least, 100 milliseconds between retries. ]*/
                          ThreadAPI_Sleep(RETRY_INTERVAL_IN_MICROSECONDS);
                      }
                  }
              }
          }
      }
  
      if ((http_instance->is_io_error != 0) && (result == HTTPAPI_OK))
      {
          /*Codes_SRS_HTTPAPI_COMPACT_21_025: [ If the open process failed, the HTTPAPI_ExecuteRequest shall not send any request and return HTTPAPI_OPEN_REQUEST_FAILED. ]*/
          result = HTTPAPI_OPEN_REQUEST_FAILED;
      }
  
      return result;
  }
  
  static HTTPAPI_RESULT conn_send_all(HTTP_HANDLE_DATA* http_instance, const unsigned char* buf, size_t bufLen)
  {
      HTTPAPI_RESULT result;
  
      http_instance->send_completed = 0;
      http_instance->is_io_error = 0;
      if (xio_send(http_instance->xio_handle, buf, bufLen, on_send_complete, http_instance) != 0)
      {
          /*Codes_SRS_HTTPAPI_COMPACT_21_028: [ If the HTTPAPI_ExecuteRequest cannot send the request header, it shall return HTTPAPI_HTTP_HEADERS_FAILED. ]*/
          result = HTTPAPI_SEND_REQUEST_FAILED;
      }
      else
      {
          /*Codes_SRS_HTTPAPI_COMPACT_21_079: [ The HTTPAPI_ExecuteRequest shall wait, at least, 20 seconds to send a buffer using the SSL connection. ]*/
          int countRetry = MAX_SEND_RETRY;
          /*Codes_SRS_HTTPAPI_COMPACT_21_033: [ If the whole process succeed, the HTTPAPI_ExecuteRequest shall retur HTTPAPI_OK. ]*/
          result = HTTPAPI_OK;
          while ((http_instance->send_completed == 0) && (result == HTTPAPI_OK))
          {
              xio_dowork(http_instance->xio_handle);
              if (http_instance->is_io_error != 0)
              {
                  /*Codes_SRS_HTTPAPI_COMPACT_21_028: [ If the HTTPAPI_ExecuteRequest cannot send the request header, it shall return HTTPAPI_HTTP_HEADERS_FAILED. ]*/
                  result = HTTPAPI_SEND_REQUEST_FAILED;
              }
              else if ((countRetry--) <= 0)
              {
                  /*Codes_SRS_HTTPAPI_COMPACT_21_080: [ If the HTTPAPI_ExecuteRequest retries to send the message for 20 seconds without success, it shall fail and return HTTPAPI_SEND_REQUEST_FAILED. ]*/
                  LogError("Send timeout. The HTTP request is incomplete");
                  /*Codes_SRS_HTTPAPI_COMPACT_21_028: [ If the HTTPAPI_ExecuteRequest cannot send the request header, it shall return HTTPAPI_HTTP_HEADERS_FAILED. ]*/
                  result = HTTPAPI_SEND_REQUEST_FAILED;
              }
              else
              {
                  /*Codes_SRS_HTTPAPI_COMPACT_21_083: [ The HTTPAPI_ExecuteRequest shall wait, at least, 100 milliseconds between retries. ]*/
                  ThreadAPI_Sleep(RETRY_INTERVAL_IN_MICROSECONDS);
              }
          }
      }
  
      return result;
  }
  
  /*Codes_SRS_HTTPAPI_COMPACT_21_035: [ The HTTPAPI_ExecuteRequest shall execute resquest for types `GET`, `POST`, `PUT`, `DELETE`, `PATCH`. ]*/
  const char httpapiRequestString[5][7] = { "GET", "POST", "PUT", "DELETE", "PATCH" };
  const char* get_request_type(HTTPAPI_REQUEST_TYPE requestType)
  {
      return (const char*)httpapiRequestString[requestType];
  }
  
  /*Codes_SRS_HTTPAPI_COMPACT_21_026: [ If the open process succeed, the HTTPAPI_ExecuteRequest shall send the request message to the host. ]*/
  static HTTPAPI_RESULT SendHeadsToXIO(HTTP_HANDLE_DATA* http_instance, HTTPAPI_REQUEST_TYPE requestType, const char* relativePath, HTTP_HEADERS_HANDLE httpHeadersHandle, size_t headersCount)
  {
      HTTPAPI_RESULT result;
      char    buf[TEMP_BUFFER_SIZE];
      int     ret;
  
      //Send request
      /*Codes_SRS_HTTPAPI_COMPACT_21_038: [ The HTTPAPI_ExecuteRequest shall execute the resquest for the path in relativePath parameter. ]*/
      /*Codes_SRS_HTTPAPI_COMPACT_21_036: [ The request type shall be provided in the parameter requestType. ]*/
      if (((ret = snprintf(buf, sizeof(buf), "%s %s HTTP/1.1\r\n", get_request_type(requestType), relativePath)) < 0) ||
          (ret >= sizeof(buf)))
      {
          /*Codes_SRS_HTTPAPI_COMPACT_21_027: [ If the HTTPAPI_ExecuteRequest cannot create a buffer to send the request, it shall not send any request and return HTTPAPI_STRING_PROCESSING_ERROR. ]*/
          result = HTTPAPI_STRING_PROCESSING_ERROR;
      }
          /*Codes_SRS_HTTPAPI_COMPACT_21_028: [ If the HTTPAPI_ExecuteRequest cannot send the request header, it shall return HTTPAPI_HTTP_HEADERS_FAILED. ]*/
      else if ((result = conn_send_all(http_instance, (const unsigned char*)buf, strlen(buf))) == HTTPAPI_OK)
      {
          //Send default headers
          /*Codes_SRS_HTTPAPI_COMPACT_21_033: [ If the whole process succeed, the HTTPAPI_ExecuteRequest shall retur HTTPAPI_OK. ]*/
          for (size_t i = 0; ((i < headersCount) && (result == HTTPAPI_OK)); i++)
          {
              char* header;
              if (HTTPHeaders_GetHeader(httpHeadersHandle, i, &header) != HTTP_HEADERS_OK)
              {
                  /*Codes_SRS_HTTPAPI_COMPACT_21_027: [ If the HTTPAPI_ExecuteRequest cannot create a buffer to send the request, it shall not send any request and return HTTPAPI_STRING_PROCESSING_ERROR. ]*/
                  result = HTTPAPI_STRING_PROCESSING_ERROR;
              }
              else
              {
                  if ((result = conn_send_all(http_instance, (const unsigned char*)header, strlen(header))) == HTTPAPI_OK)
                  {
                      result = conn_send_all(http_instance, (const unsigned char*)"\r\n", (size_t)2);
                  }
                  free(header);
              }
          }
  
          //Close headers
          if (result == HTTPAPI_OK)
          {
              result = conn_send_all(http_instance, (const unsigned char*)"\r\n", (size_t)2);
          }
      }
      return result;
  }
  
  /*Codes_SRS_HTTPAPI_COMPACT_21_042: [ The request can contain the a content message, provided in content parameter. ]*/
  static HTTPAPI_RESULT SendContentToXIO(HTTP_HANDLE_DATA* http_instance, const unsigned char* content, size_t contentLength)
  {
      HTTPAPI_RESULT result;
  
      //Send data (if available)
      /*Codes_SRS_HTTPAPI_COMPACT_21_045: [ If the contentLength is lower than one, the HTTPAPI_ExecuteRequest shall send the request without content. ]*/
      if (content && contentLength > 0)
      {
          /*Codes_SRS_HTTPAPI_COMPACT_21_044: [ If the content is not NULL, the number of bytes in the content shall be provided in contentLength parameter. ]*/
          result = conn_send_all(http_instance, content, contentLength);
      }
      else
      {
          /*Codes_SRS_HTTPAPI_COMPACT_21_043: [ If the content is NULL, the HTTPAPI_ExecuteRequest shall send the request without content. ]*/
          /*Codes_SRS_HTTPAPI_COMPACT_21_033: [ If the whole process succeed, the HTTPAPI_ExecuteRequest shall retur HTTPAPI_OK. ]*/
          result = HTTPAPI_OK;
      }
      return result;
  }
  
  /*Codes_SRS_HTTPAPI_COMPACT_21_030: [ At the end of the transmission, the HTTPAPI_ExecuteRequest shall receive the response from the host. ]*/
  static HTTPAPI_RESULT RecieveHeaderFromXIO(HTTP_HANDLE_DATA* http_instance, unsigned int* statusCode)
  {
      HTTPAPI_RESULT result;
      char    buf[TEMP_BUFFER_SIZE];
      int     ret;
  
      http_instance->is_io_error = 0;
  
      //Receive response
      if (readLine(http_instance, buf, TEMP_BUFFER_SIZE) < 0)
      {
          /*Codes_SRS_HTTPAPI_COMPACT_21_032: [ If the HTTPAPI_ExecuteRequest cannot read the message with the request result, it shall return HTTPAPI_READ_DATA_FAILED. ]*/
          /*Codes_SRS_HTTPAPI_COMPACT_21_082: [ If the HTTPAPI_ExecuteRequest retries 20 seconds to receive the message without success, it shall fail and return HTTPAPI_READ_DATA_FAILED. ]*/
          result = HTTPAPI_READ_DATA_FAILED;
      }
      //Parse HTTP response
      else if (ParseHttpResponse(buf, &ret) != 1)
      {
          //Cannot match string, error
          /*Codes_SRS_HTTPAPI_COMPACT_21_055: [ If the HTTPAPI_ExecuteRequest cannot parser the recived message, it shall return HTTPAPI_RECEIVE_RESPONSE_FAILED. ]*/
          LogInfo("Not a correct HTTP answer");
          result = HTTPAPI_RECEIVE_RESPONSE_FAILED;
      }
      else
      {
          /*Codes_SRS_HTTPAPI_COMPACT_21_046: [ The HTTPAPI_ExecuteRequest shall return the http status reported by the host in the received response. ]*/
          /*Codes_SRS_HTTPAPI_COMPACT_21_048: [ If the statusCode is NULL, the HTTPAPI_ExecuteRequest shall report not report any status. ]*/
          if (statusCode)
          {
              /*Codes_SRS_HTTPAPI_COMPACT_21_047: [ The HTTPAPI_ExecuteRequest shall report the status in the statusCode parameter. ]*/
              *statusCode = ret;
          }
          /*Codes_SRS_HTTPAPI_COMPACT_21_033: [ If the whole process succeed, the HTTPAPI_ExecuteRequest shall retur HTTPAPI_OK. ]*/
          result = HTTPAPI_OK;
      }
  
      return result;
  }
  
  static HTTPAPI_RESULT RecieveContentInfoFromXIO(HTTP_HANDLE_DATA* http_instance, HTTP_HEADERS_HANDLE responseHeadersHandle, size_t* bodyLength, bool* chunked)
  {
      HTTPAPI_RESULT result;
      char    buf[TEMP_BUFFER_SIZE];
      const char* substr;
      char* whereIsColon;
      int lengthInMsg;
      const char* ContentLength = "content-length:";
      const int ContentLengthSize = 16;
      const char* TransferEncoding = "transfer-encoding:";
      const int TransferEncodingSize = 19;
      const char* Chunked = "chunked";
      const int ChunkedSize = 8;
  
      http_instance->is_io_error = 0;
  
      //Read HTTP response headers
      if (readLine(http_instance, buf, sizeof(buf)) < 0)
      {
          /*Codes_SRS_HTTPAPI_COMPACT_21_032: [ If the HTTPAPI_ExecuteRequest cannot read the message with the request result, it shall return HTTPAPI_READ_DATA_FAILED. ]*/
          /*Codes_SRS_HTTPAPI_COMPACT_21_082: [ If the HTTPAPI_ExecuteRequest retries 20 seconds to receive the message without success, it shall fail and return HTTPAPI_READ_DATA_FAILED. ]*/
          result = HTTPAPI_READ_DATA_FAILED;
      }
      else
      {
          /*Codes_SRS_HTTPAPI_COMPACT_21_033: [ If the whole process succeed, the HTTPAPI_ExecuteRequest shall retur HTTPAPI_OK. ]*/
          result = HTTPAPI_OK;
  
          while (*buf && (result == HTTPAPI_OK))
          {
              if (InternStrnicmp(buf, ContentLength, ContentLengthSize) == 0)
              {
                  substr = buf + ContentLengthSize - 1;
                  if (ParseStringToDecimal(substr, &lengthInMsg) != 1)
                  {
                      /*Codes_SRS_HTTPAPI_COMPACT_21_032: [ If the HTTPAPI_ExecuteRequest cannot read the message with the request result, it shall return HTTPAPI_READ_DATA_FAILED. ]*/
                      result = HTTPAPI_READ_DATA_FAILED;
                  }
                  else
                  {
                      (*bodyLength) = (size_t)lengthInMsg;
                  }
              }
              else if (InternStrnicmp(buf, TransferEncoding, TransferEncodingSize) == 0)
              {
                  substr = buf + TransferEncodingSize - 1;
  
                  while (isspace(*substr)) substr++;
  
                  if (InternStrnicmp(substr, Chunked, ChunkedSize) == 0)
                  {
                      (*chunked) = true;
                  }
              }
  
              if (result == HTTPAPI_OK)
              {
                  whereIsColon = strchr((char*)buf, ':');
                  /*Codes_SRS_HTTPAPI_COMPACT_21_049: [ If responseHeadersHandle is provide, the HTTPAPI_ExecuteRequest shall prepare a Response Header usign the HTTPHeaders_AddHeaderNameValuePair. ]*/
                  if (whereIsColon && (responseHeadersHandle != NULL))
                  {
                      *whereIsColon = '\0';
                      HTTPHeaders_AddHeaderNameValuePair(responseHeadersHandle, buf, whereIsColon + 1);
                  }
  
                  if (readLine(http_instance, buf, sizeof(buf)) < 0)
                  {
                      /*Codes_SRS_HTTPAPI_COMPACT_21_032: [ If the HTTPAPI_ExecuteRequest cannot read the message with the request result, it shall return HTTPAPI_READ_DATA_FAILED. ]*/
                      /*Codes_SRS_HTTPAPI_COMPACT_21_082: [ If the HTTPAPI_ExecuteRequest retries 20 seconds to receive the message without success, it shall fail and return HTTPAPI_READ_DATA_FAILED. ]*/
                      result = HTTPAPI_READ_DATA_FAILED;
                  }
              }
          }
      }
  
      return result;
  }
  
  static HTTPAPI_RESULT ReadHTTPResponseBodyFromXIO(HTTP_HANDLE_DATA* http_instance, size_t bodyLength, bool chunked, BUFFER_HANDLE responseContent)
  {
      HTTPAPI_RESULT result;
      char    buf[TEMP_BUFFER_SIZE];
      const unsigned char* receivedContent;
  
      http_instance->is_io_error = 0;
  
      //Read HTTP response body
      if (!chunked)
      {
          if (bodyLength)
          {
              if (responseContent != NULL)
              {
                  if (BUFFER_pre_build(responseContent, bodyLength) != 0)
                  {
                      /*Codes_SRS_HTTPAPI_COMPACT_21_052: [ If any memory allocation get fail, the HTTPAPI_ExecuteRequest shall return HTTPAPI_ALLOC_FAILED. ]*/
                      result = HTTPAPI_ALLOC_FAILED;
                  }
                  else if (BUFFER_content(responseContent, &receivedContent) != 0)
                  {
                      (void)BUFFER_unbuild(responseContent);
  
                      /*Codes_SRS_HTTPAPI_COMPACT_21_052: [ If any memory allocation get fail, the HTTPAPI_ExecuteRequest shall return HTTPAPI_ALLOC_FAILED. ]*/
                      result = HTTPAPI_ALLOC_FAILED;
                  }
                  else if (readChunk(http_instance, (char*)receivedContent, bodyLength) < 0)
                  {
                      /*Codes_SRS_HTTPAPI_COMPACT_21_032: [ If the HTTPAPI_ExecuteRequest cannot read the message with the request result, it shall return HTTPAPI_READ_DATA_FAILED. ]*/
                      result = HTTPAPI_READ_DATA_FAILED;
                  }
                  else
                  {
                      /*Codes_SRS_HTTPAPI_COMPACT_21_033: [ If the whole process succeed, the HTTPAPI_ExecuteRequest shall retur HTTPAPI_OK. ]*/
                      result = HTTPAPI_OK;
                  }
              }
              else
              {
                  /*Codes_SRS_HTTPAPI_COMPACT_21_051: [ If the responseContent is NULL, the HTTPAPI_ExecuteRequest shall ignore any content in the response. ]*/
                  if (skipN(http_instance, bodyLength) < 0)
                  {
                      /*Codes_SRS_HTTPAPI_COMPACT_21_082: [ If the HTTPAPI_ExecuteRequest retries 20 seconds to receive the message without success, it shall fail and return HTTPAPI_READ_DATA_FAILED. ]*/
                      result = HTTPAPI_READ_DATA_FAILED;
                  }
                  else
                  {
                      result = HTTPAPI_OK;
                  }
              }
          }
          else
          {
              /*Codes_SRS_HTTPAPI_COMPACT_21_033: [ If the whole process succeed, the HTTPAPI_ExecuteRequest shall retur HTTPAPI_OK. ]*/
              result = HTTPAPI_OK;
          }
      }
      else
      {
          size_t size = 0;
          /*Codes_SRS_HTTPAPI_COMPACT_21_033: [ If the whole process succeed, the HTTPAPI_ExecuteRequest shall retur HTTPAPI_OK. ]*/
          result = HTTPAPI_OK;
          while (result == HTTPAPI_OK)
          {
              size_t chunkSize;
              if (readLine(http_instance, buf, sizeof(buf)) < 0)    // read [length in hex]/r/n
              {
                  /*Codes_SRS_HTTPAPI_COMPACT_21_032: [ If the HTTPAPI_ExecuteRequest cannot read the message with the request result, it shall return HTTPAPI_READ_DATA_FAILED. ]*/
                  /*Codes_SRS_HTTPAPI_COMPACT_21_082: [ If the HTTPAPI_ExecuteRequest retries 20 seconds to receive the message without success, it shall fail and return HTTPAPI_READ_DATA_FAILED. ]*/
                  result = HTTPAPI_READ_DATA_FAILED;
              }
              else if (ParseStringToHexadecimal(buf, &chunkSize) != 1)     // chunkSize is length of next line (/r/n is not counted)
              {
                  //Cannot match string, error
                  /*Codes_SRS_HTTPAPI_COMPACT_21_055: [ If the HTTPAPI_ExecuteRequest cannot parser the recived message, it shall return HTTPAPI_RECEIVE_RESPONSE_FAILED. ]*/
                  result = HTTPAPI_RECEIVE_RESPONSE_FAILED;
              }
              else if (chunkSize == 0)
              {
                  // 0 length means next line is just '\r\n' and end of chunks
                  if (readChunk(http_instance, (char*)buf, (size_t)2) < 0
                      || buf[0] != '\r' || buf[1] != '\n') // skip /r/n
                  {
                      (void)BUFFER_unbuild(responseContent);
  
                      result = HTTPAPI_READ_DATA_FAILED;
                  }
                  break;
              }
              else
              {
                  if (responseContent != NULL)
                  {
                      if (BUFFER_enlarge(responseContent, chunkSize) != 0)
                      {
                          (void)BUFFER_unbuild(responseContent);
  
                          /*Codes_SRS_HTTPAPI_COMPACT_21_052: [ If any memory allocation get fail, the HTTPAPI_ExecuteRequest shall return HTTPAPI_ALLOC_FAILED. ]*/
                          result = HTTPAPI_ALLOC_FAILED;
                      }
                      else if (BUFFER_content(responseContent, &receivedContent) != 0)
                      {
                          (void)BUFFER_unbuild(responseContent);
  
                          /*Codes_SRS_HTTPAPI_COMPACT_21_052: [ If any memory allocation get fail, the HTTPAPI_ExecuteRequest shall return HTTPAPI_ALLOC_FAILED. ]*/
                          result = HTTPAPI_ALLOC_FAILED;
                      }
                      else if (readChunk(http_instance, (char*)receivedContent + size, chunkSize) < 0)
                      {
                          result = HTTPAPI_READ_DATA_FAILED;
                      }
                  }
                  else
                  {
                      /*Codes_SRS_HTTPAPI_COMPACT_21_051: [ If the responseContent is NULL, the HTTPAPI_ExecuteRequest shall ignore any content in the response. ]*/
                      if (skipN(http_instance, chunkSize) < 0)
                      {
                          /*Codes_SRS_HTTPAPI_COMPACT_21_082: [ If the HTTPAPI_ExecuteRequest retries 20 seconds to receive the message without success, it shall fail and return HTTPAPI_READ_DATA_FAILED. ]*/
                          result = HTTPAPI_READ_DATA_FAILED;
                      }
                  }
  
                  if (result == HTTPAPI_OK)
                  {
                      if (readChunk(http_instance, (char*)buf, (size_t)2) < 0
                          || buf[0] != '\r' || buf[1] != '\n') // skip /r/n
                      {
                          result = HTTPAPI_READ_DATA_FAILED;
                      }
                      size += chunkSize;
                  }
              }
          }
  
      }
      return result;
  }
  
  
  /*Codes_SRS_HTTPAPI_COMPACT_21_037: [ If the request type is unknown, the HTTPAPI_ExecuteRequest shall return HTTPAPI_INVALID_ARG. ]*/
  static bool validRequestType(HTTPAPI_REQUEST_TYPE requestType)
  {
      bool result;
  
      if ((requestType == HTTPAPI_REQUEST_GET) ||
          (requestType == HTTPAPI_REQUEST_POST) ||
          (requestType == HTTPAPI_REQUEST_PUT) ||
          (requestType == HTTPAPI_REQUEST_DELETE) ||
          (requestType == HTTPAPI_REQUEST_PATCH))
      {
          result = true;
      }
      else
      {
          result = false;
      }
  
      return result;
  }
  
  /*Codes_SRS_HTTPAPI_COMPACT_21_021: [ The HTTPAPI_ExecuteRequest shall execute the http communtication with the provided host, sending a request and reciving the response. ]*/
  /*Codes_SRS_HTTPAPI_COMPACT_21_050: [ If there is a content in the response, the HTTPAPI_ExecuteRequest shall copy it in the responseContent buffer. ]*/
  //Note: This function assumes that "Host:" and "Content-Length:" headers are setup
  //      by the caller of HTTPAPI_ExecuteRequest() (which is true for httptransport.c).
  HTTPAPI_RESULT HTTPAPI_ExecuteRequest(HTTP_HANDLE handle, HTTPAPI_REQUEST_TYPE requestType, const char* relativePath,
      HTTP_HEADERS_HANDLE httpHeadersHandle, const unsigned char* content,
      size_t contentLength, unsigned int* statusCode,
      HTTP_HEADERS_HANDLE responseHeadersHandle, BUFFER_HANDLE responseContent)
  {
      HTTPAPI_RESULT result = HTTPAPI_ERROR;
      size_t  headersCount;
      size_t  bodyLength = 0;
      bool    chunked = false;
      HTTP_HANDLE_DATA* http_instance = (HTTP_HANDLE_DATA*)handle;
  
      /*Codes_SRS_HTTPAPI_COMPACT_21_034: [ If there is no previous connection, the HTTPAPI_ExecuteRequest shall return HTTPAPI_INVALID_ARG. ]*/
      /*Codes_SRS_HTTPAPI_COMPACT_21_037: [ If the request type is unknown, the HTTPAPI_ExecuteRequest shall return HTTPAPI_INVALID_ARG. ]*/
      /*Codes_SRS_HTTPAPI_COMPACT_21_039: [ If the relativePath is NULL or invalid, the HTTPAPI_ExecuteRequest shall return HTTPAPI_INVALID_ARG. ]*/
      /*Codes_SRS_HTTPAPI_COMPACT_21_041: [ If the httpHeadersHandle is NULL or invalid, the HTTPAPI_ExecuteRequest shall return HTTPAPI_INVALID_ARG. ]*/
      /*Codes_SRS_HTTPAPI_COMPACT_21_053: [ The HTTPAPI_ExecuteRequest shall produce a set of http header to send to the host. ]*/
      /*Codes_SRS_HTTPAPI_COMPACT_21_040: [ The request shall contain the http header provided in httpHeadersHandle parameter. ]*/
      /*Codes_SRS_HTTPAPI_COMPACT_21_054: [ If Http header maker cannot provide the number of headers, the HTTPAPI_ExecuteRequest shall return HTTPAPI_INVALID_ARG. ]*/
      if (http_instance == NULL ||
          relativePath == NULL ||
          httpHeadersHandle == NULL ||
          !validRequestType(requestType) ||
          HTTPHeaders_GetHeaderCount(httpHeadersHandle, &headersCount) != HTTP_HEADERS_OK)
      {
          result = HTTPAPI_INVALID_ARG;
          LogError("(result = %s)", ENUM_TO_STRING(HTTPAPI_RESULT, result));
      }
      /*Codes_SRS_HTTPAPI_COMPACT_21_024: [ The HTTPAPI_ExecuteRequest shall open the transport connection with the host to send the request. ]*/
      else if ((result = OpenXIOConnection(http_instance)) != HTTPAPI_OK)
      {
          LogError("Open HTTP connection failed (result = %s)", ENUM_TO_STRING(HTTPAPI_RESULT, result));
      }
      /*Codes_SRS_HTTPAPI_COMPACT_21_026: [ If the open process succeed, the HTTPAPI_ExecuteRequest shall send the request message to the host. ]*/
      else if ((result = SendHeadsToXIO(http_instance, requestType, relativePath, httpHeadersHandle, headersCount)) != HTTPAPI_OK)
      {
          LogError("Send heads to HTTP failed (result = %s)", ENUM_TO_STRING(HTTPAPI_RESULT, result));
      }
      /*Codes_SRS_HTTPAPI_COMPACT_21_042: [ The request can contain the a content message, provided in content parameter. ]*/
      else if ((result = SendContentToXIO(http_instance, content, contentLength)) != HTTPAPI_OK)
      {
          LogError("Send content to HTTP failed (result = %s)", ENUM_TO_STRING(HTTPAPI_RESULT, result));
      }
      /*Codes_SRS_HTTPAPI_COMPACT_21_030: [ At the end of the transmission, the HTTPAPI_ExecuteRequest shall receive the response from the host. ]*/
      /*Codes_SRS_HTTPAPI_COMPACT_21_073: [ The message recived by the HTTPAPI_ExecuteRequest shall starts with a valid header. ]*/
      else if ((result = RecieveHeaderFromXIO(http_instance, statusCode)) != HTTPAPI_OK)
      {
          LogError("Receive header from HTTP failed (result = %s)", ENUM_TO_STRING(HTTPAPI_RESULT, result));
      }
      /*Codes_SRS_HTTPAPI_COMPACT_21_074: [ After the header, the message recieved by the HTTPAPI_ExecuteRequest can contain addition information about the content. ]*/
      else if ((result = RecieveContentInfoFromXIO(http_instance, responseHeadersHandle, &bodyLength, &chunked)) != HTTPAPI_OK)
      {
          LogError("Receive content information from HTTP failed (result = %s)", ENUM_TO_STRING(HTTPAPI_RESULT, result));
      }
      /*Codes_SRS_HTTPAPI_COMPACT_21_075: [ The message recieved by the HTTPAPI_ExecuteRequest can contain a body with the message content. ]*/
      else if ((result = ReadHTTPResponseBodyFromXIO(http_instance, bodyLength, chunked, responseContent)) != HTTPAPI_OK)
      {
          LogError("Read HTTP response body from HTTP failed (result = %s)", ENUM_TO_STRING(HTTPAPI_RESULT, result));
      }
  
      conn_receive_discard_buffer(http_instance);
  
  
      return result;
  }
  
  /*Codes_SRS_HTTPAPI_COMPACT_21_056: [ The HTTPAPI_SetOption shall change the HTTP options. ]*/
  /*Codes_SRS_HTTPAPI_COMPACT_21_057: [ The HTTPAPI_SetOption shall recieve a handle that identiry the HTTP connection. ]*/
  /*Codes_SRS_HTTPAPI_COMPACT_21_058: [ The HTTPAPI_SetOption shall recieve the option as a pair optionName/value. ]*/
  HTTPAPI_RESULT HTTPAPI_SetOption(HTTP_HANDLE handle, const char* optionName, const void* value)
  {
      HTTPAPI_RESULT result;
      HTTP_HANDLE_DATA* http_instance = (HTTP_HANDLE_DATA*)handle;
  
      if (
          (http_instance == NULL) ||
          (optionName == NULL) ||
          (value == NULL)
          )
      {
          /*Codes_SRS_HTTPAPI_COMPACT_21_059: [ If the handle is NULL, the HTTPAPI_SetOption shall return HTTPAPI_INVALID_ARG. ]*/
          /*Codes_SRS_HTTPAPI_COMPACT_21_060: [ If the optionName is NULL, the HTTPAPI_SetOption shall return HTTPAPI_INVALID_ARG. ]*/
          /*Codes_SRS_HTTPAPI_COMPACT_21_061: [ If the value is NULL, the HTTPAPI_SetOption shall return HTTPAPI_INVALID_ARG. ]*/
          result = HTTPAPI_INVALID_ARG;
      }
      else if (strcmp("TrustedCerts", optionName) == 0)
      {
          if (http_instance->certificate)
          {
              free(http_instance->certificate);
          }
  
          int len = (int)strlen((char*)value);
          http_instance->certificate = (char*)malloc((len + 1) * sizeof(char));
          if (http_instance->certificate == NULL)
          {
              /*Codes_SRS_HTTPAPI_COMPACT_21_062: [ If any memory allocation get fail, the HTTPAPI_SetOption shall return HTTPAPI_ALLOC_FAILED. ]*/
              result = HTTPAPI_ALLOC_FAILED;
              LogInfo("unable to allocate memory for the certificate in HTTPAPI_SetOption");
          }
          else
          {
              /*Codes_SRS_HTTPAPI_COMPACT_21_064: [ If the HTTPAPI_SetOption get success setting the option, it shall return HTTPAPI_OK. ]*/
              (void)strcpy(http_instance->certificate, (const char*)value);
              result = HTTPAPI_OK;
          }
      }
      else if (strcmp(SU_OPTION_X509_CERT, optionName) == 0)
      {
          if (http_instance->x509ClientCertificate)
          {
              free(http_instance->x509ClientCertificate);
          }
  
          int len = (int)strlen((char*)value);
          http_instance->x509ClientCertificate = (char*)malloc((len + 1) * sizeof(char));
          if (http_instance->x509ClientCertificate == NULL)
          {
              /*Codes_SRS_HTTPAPI_COMPACT_21_062: [ If any memory allocation get fail, the HTTPAPI_SetOption shall return HTTPAPI_ALLOC_FAILED. ]*/
              result = HTTPAPI_ALLOC_FAILED;
              LogInfo("unable to allocate memory for the client certificate in HTTPAPI_SetOption");
          }
          else
          {
              /*Codes_SRS_HTTPAPI_COMPACT_21_064: [ If the HTTPAPI_SetOption get success setting the option, it shall return HTTPAPI_OK. ]*/
              (void)strcpy(http_instance->x509ClientCertificate, (const char*)value);
              result = HTTPAPI_OK;
          }
      }
      else if (strcmp(SU_OPTION_X509_PRIVATE_KEY, optionName) == 0)
      {
          if (http_instance->x509ClientPrivateKey)
          {
              free(http_instance->x509ClientPrivateKey);
          }
  
          int len = (int)strlen((char*)value);
          http_instance->x509ClientPrivateKey = (char*)malloc((len + 1) * sizeof(char));
          if (http_instance->x509ClientPrivateKey == NULL)
          {
              /*Codes_SRS_HTTPAPI_COMPACT_21_062: [ If any memory allocation get fail, the HTTPAPI_SetOption shall return HTTPAPI_ALLOC_FAILED. ]*/
              result = HTTPAPI_ALLOC_FAILED;
              LogInfo("unable to allocate memory for the client private key in HTTPAPI_SetOption");
          }
          else
          {
              /*Codes_SRS_HTTPAPI_COMPACT_21_064: [ If the HTTPAPI_SetOption get success setting the option, it shall return HTTPAPI_OK. ]*/
              (void)strcpy(http_instance->x509ClientPrivateKey, (const char*)value);
              result = HTTPAPI_OK;
          }
      }
      else
      {
          /*Codes_SRS_HTTPAPI_COMPACT_21_063: [ If the HTTP do not support the optionName, the HTTPAPI_SetOption shall return HTTPAPI_INVALID_ARG. ]*/
          result = HTTPAPI_INVALID_ARG;
          LogInfo("unknown option %s", optionName);
      }
      return result;
  }
  
  /*Codes_SRS_HTTPAPI_COMPACT_21_065: [ The HTTPAPI_CloneOption shall provide the means to clone the HTTP option. ]*/
  /*Codes_SRS_HTTPAPI_COMPACT_21_066: [ The HTTPAPI_CloneOption shall return a clone of the value identified by the optionName. ]*/
  HTTPAPI_RESULT HTTPAPI_CloneOption(const char* optionName, const void* value, const void** savedValue)
  {
      HTTPAPI_RESULT result;
      size_t certLen;
      char* tempCert;
  
      if (
          (optionName == NULL) ||
          (value == NULL) ||
          (savedValue == NULL)
          )
      {
          /*Codes_SRS_HTTPAPI_COMPACT_21_067: [ If the optionName is NULL, the HTTPAPI_CloneOption shall return HTTPAPI_INVALID_ARG. ]*/
          /*Codes_SRS_HTTPAPI_COMPACT_21_068: [ If the value is NULL, the HTTPAPI_CloneOption shall return HTTPAPI_INVALID_ARG. ]*/
          /*Codes_SRS_HTTPAPI_COMPACT_21_069: [ If the savedValue is NULL, the HTTPAPI_CloneOption shall return HTTPAPI_INVALID_ARG. ]*/
          result = HTTPAPI_INVALID_ARG;
      }
      else if (strcmp("TrustedCerts", optionName) == 0)
      {
          certLen = strlen((const char*)value);
          tempCert = (char*)malloc((certLen + 1) * sizeof(char));
          if (tempCert == NULL)
          {
              /*Codes_SRS_HTTPAPI_COMPACT_21_070: [ If any memory allocation get fail, the HTTPAPI_CloneOption shall return HTTPAPI_ALLOC_FAILED. ]*/
              result = HTTPAPI_ALLOC_FAILED;
          }
          else
          {
              /*Codes_SRS_HTTPAPI_COMPACT_21_072: [ If the HTTPAPI_CloneOption get success setting the option, it shall return HTTPAPI_OK. ]*/
              (void)strcpy(tempCert, (const char*)value);
              *savedValue = tempCert;
              result = HTTPAPI_OK;
          }
      }
      else if (strcmp(SU_OPTION_X509_CERT, optionName) == 0)
      {
          certLen = strlen((const char*)value);
          tempCert = (char*)malloc((certLen + 1) * sizeof(char));
          if (tempCert == NULL)
          {
              /*Codes_SRS_HTTPAPI_COMPACT_21_070: [ If any memory allocation get fail, the HTTPAPI_CloneOption shall return HTTPAPI_ALLOC_FAILED. ]*/
              result = HTTPAPI_ALLOC_FAILED;
          }
          else
          {
              /*Codes_SRS_HTTPAPI_COMPACT_21_072: [ If the HTTPAPI_CloneOption get success setting the option, it shall return HTTPAPI_OK. ]*/
              (void)strcpy(tempCert, (const char*)value);
              *savedValue = tempCert;
              result = HTTPAPI_OK;
          }
      }
      else if (strcmp(SU_OPTION_X509_PRIVATE_KEY, optionName) == 0)
      {
          certLen = strlen((const char*)value);
          tempCert = (char*)malloc((certLen + 1) * sizeof(char));
          if (tempCert == NULL)
          {
              /*Codes_SRS_HTTPAPI_COMPACT_21_070: [ If any memory allocation get fail, the HTTPAPI_CloneOption shall return HTTPAPI_ALLOC_FAILED. ]*/
              result = HTTPAPI_ALLOC_FAILED;
          }
          else
          {
              /*Codes_SRS_HTTPAPI_COMPACT_21_072: [ If the HTTPAPI_CloneOption get success setting the option, it shall return HTTPAPI_OK. ]*/
              (void)strcpy(tempCert, (const char*)value);
              *savedValue = tempCert;
              result = HTTPAPI_OK;
          }
      }
      else
      {
          /*Codes_SRS_HTTPAPI_COMPACT_21_071: [ If the HTTP do not support the optionName, the HTTPAPI_CloneOption shall return HTTPAPI_INVALID_ARG. ]*/
          result = HTTPAPI_INVALID_ARG;
          LogInfo("unknown option %s", optionName);
      }
      return result;
  }
  