text: /*
   * Amazon FreeRTOS HTTPS Client V1.0.0
   * Copyright (C) 2019 Amazon.com, Inc. or its affiliates.  All Rights Reserved.
   *
   * Permission is hereby granted, free of charge, to any person obtaining a copy of
   * this software and associated documentation files (the "Software"), to deal in
   * the Software without restriction, including without limitation the rights to
   * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
   * the Software, and to permit persons to whom the Software is furnished to do so,
   * subject to the following conditions:
   *
   * The above copyright notice and this permission notice shall be included in all
   * copies or substantial portions of the Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
   * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
   * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
   * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
   * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
   *
   * http://aws.amazon.com/freertos
   * http://www.FreeRTOS.org
   */
  
  /**
   * @file iot_https_client.c
   * @brief Implementation of the user-facing functions of the Amazon FreeRTOS HTTPS Client library.
   */
  
  /* The config header is always included first. */
  #include "iot_config.h"
  
  /* HTTPS Client library private includes. */
  #include "private/iot_https_internal.h"
  
  /*-----------------------------------------------------------*/
  
  /**
   * @brief Partial HTTPS request first line.
   *
   * This is used for the calculation of the requestUserBufferMinimumSize.
   * The minimum path is "/" because we cannot know how long the application requested path is is going to be.
   * CONNECT is the longest string length HTTP method according to RFC 2616.
   */
  #define HTTPS_PARTIAL_REQUEST_LINE                        HTTPS_CONNECT_METHOD " " HTTPS_EMPTY_PATH " " HTTPS_PROTOCOL_VERSION
  
  /**
   * @brief The User-Agent header line string.
   *
   * This is of the form:
   * "User-Agent: <configured-user-agent>\r\n"
   * This is used for the calculation of the requestUserBufferMinimumSize.
   */
  #define HTTPS_USER_AGENT_HEADER_LINE                      HTTPS_USER_AGENT_HEADER HTTPS_HEADER_FIELD_SEPARATOR IOT_HTTPS_USER_AGENT HTTPS_END_OF_HEADER_LINES_INDICATOR
  
  /**
   * @brief The Host header line with the field only and not the value.
   *
   * This is of the form:
   * "Host: \r\n"
   * This is used for the calculation of the requestUserBufferMinimumSize. The Host value is not specified because we
   * cannot anticipate what server the client is making requests to.
   */
  #define HTTPS_PARTIAL_HOST_HEADER_LINE                    HTTPS_HOST_HEADER HTTPS_HEADER_FIELD_SEPARATOR HTTPS_END_OF_HEADER_LINES_INDICATOR
  
  /**
   * String constants for the Connection header and possible values.
   *
   * This is used for writing headers automatically during the sending of the HTTP request.
   * "Connection: keep-alive\r\n" is written automatically for a persistent connection.
   * "Connection: close\r\n" is written automatically for a non-presistent connection.
   */
  #define HTTPS_CONNECTION_KEEP_ALIVE_HEADER_LINE           HTTPS_CONNECTION_HEADER HTTPS_HEADER_FIELD_SEPARATOR HTTPS_CONNECTION_KEEP_ALIVE_HEADER_VALUE HTTPS_END_OF_HEADER_LINES_INDICATOR /**< @brief String literal for "Connection: keep-alive\r\n". */
  #define HTTPS_CONNECTION_CLOSE_HEADER_LINE                HTTPS_CONNECTION_HEADER HTTPS_HEADER_FIELD_SEPARATOR HTTPS_CONNECTION_CLOSE_HEADER_VALUE HTTPS_END_OF_HEADER_LINES_INDICATOR      /**< @brief String literal for "Connection: close\r\n". */
  
  /**
   * @brief The length of the "Connection: keep-alive\r\n" header.
   *
   * This is used for sizing a local buffer for the final headers to send that include the "Connection: keep-alive\r\n"
   * header line.
   *
   * This is used to initialize a local array for the final headers to send.
   */
  #define HTTPS_CONNECTION_KEEP_ALIVE_HEADER_LINE_LENGTH    ( 24 )
  
  /**
   * Indicates for the http-parser parsing execution function to tell it to keep parsing or to stop parsing.
   *
   * A value of 0 means the parser should keep parsing if there is more unparsed length.
   * A value greater than 0 tells the parser to stop parsing.
   */
  #define KEEP_PARSING                                      ( ( int ) 0 ) /**< @brief Indicator in the http-parser callback to keep parsing when the function returns. */
  #define STOP_PARSING                                      ( ( int ) 1 ) /**< @brief Indicator in the http-parser callback to stop parsing when the function returns. */
  
  /*-----------------------------------------------------------*/
  
  /**
   * @brief Minimum size of the request user buffer.
   *
   * The request user buffer is configured in IotHttpsClientRequestInfo_t.userBuffer. This buffer stores the internal context
   * of the request and then the request headers right after. The minimum size for the buffer is the total size of the
   * internal request context, the HTTP formatted request line, the User-Agent header line, and the part of the Host
   * header line.
   */
  const uint32_t requestUserBufferMinimumSize = sizeof( _httpsRequest_t ) +
                                                sizeof( HTTPS_PARTIAL_REQUEST_LINE ) +
                                                sizeof( HTTPS_USER_AGENT_HEADER_LINE ) +
                                                sizeof( HTTPS_PARTIAL_HOST_HEADER_LINE );
  
  /**
   * @brief Minimum size of the response user buffer.
   *
   * The response user buffer is configured in IotHttpsClientRequestInfo_t.userBuffer. This buffer stores the internal context
   * of the response and then the response headers right after. This minimum size is calculated for the case if no bytes
   * from the HTTP response headers are to be stored.
   */
  const uint32_t responseUserBufferMinimumSize = sizeof( _httpsResponse_t );
  
  /**
   * @brief Minimum size of the connection user buffer.
   *
   * The connection user buffer is configured in IotHttpsConnectionInfo_t.userBuffer. This buffer stores the internal context of the
   * connection.
   */
  const uint32_t connectionUserBufferMinimumSize = sizeof( _httpsConnection_t );
  
  /*-----------------------------------------------------------*/
  
  /**
   * @brief Callback from http-parser to indicate the start of the HTTP response message is reached.
   *
   * See https://github.com/nodejs/http-parser for more information.
   *
   * @param[in] pHttpParser - http-parser state structure.
   *
   * @return 0 to tell http-parser to keep parsing.
   *         1 to tell http-parser that parsing should stop return from http_parser_execute with error HPE_CB_message_begin.
   */
  static int _httpParserOnMessageBeginCallback( http_parser * pHttpParser );
  
  /**
   * @brief Callback from http-parser to indicate it found the HTTP response status code.
   *
   * See https://github.com/nodejs/http-parser for more information.
   *
   * @param[in] pHttpParser - http-parser state structure.
   * @param[in] pLoc - Pointer to the HTTP response status code string in the response message buffer.
   * @param[in] length - The length of the HTTP response status code string.
   *
   * @return 0 to tell http-parser to keep parsing.
   *         1 to tell http-parser that parsing should stop return from http_parser_execute with error HPE_CB_status.
   */
  static int _httpParserOnStatusCallback( http_parser * pHttpParser,
                                          const char * pLoc,
                                          size_t length );
  
  /**
   * @brief Callback from http-parser to indicate it found an HTTP response header field.
   *
   * If only part of the header field was returned here in this callback, then this callback will be invoked again the
   * next time the parser executes on the next part of the header field.
   *
   * See https://github.com/nodejs/http-parser for more information.
   *
   * @param[in] pHttpParser - http-parser state structure.
   * @param[in] pLoc - Pointer to the header field string in the response message buffer.
   * @param[in] length - The length of the header field.
   *
   * @return 0 to tell http-parser to keep parsing.
   *         1 to tell http-parser that parsing should stop return from http_parser_execute with error HPE_CB_header_field.
   */
  static int _httpParserOnHeaderFieldCallback( http_parser * pHttpParser,
                                               const char * pLoc,
                                               size_t length );
  
  /**
   * @brief Callback from http-parser to indicate it found an HTTP response header value.
   *
   * This value corresponds to the field that was found in the _httpParserOnHeaderFieldCallback() called immediately
   * before this callback was called.
   *
   * If only part of the header value was returned here in this callback, then this callback will be invoked again the
   * next time the parser executes on the next part of the header value.
   *
   * See https://github.com/nodejs/http-parser for more information.
   *
   * @param[in] pHttpParser - http-parser state structure.
   * @param[in] pLoc - Pointer to the header value string in the response message buffer.
   * @param[in] length - The length of the header value.
   *
   * @return 0 to tell http-parser to keep parsing.
   *         1 to tell http-parser that parsing should stop return from http_parser_execute with error HPE_CB_header_value.
   */
  static int _httpParserOnHeaderValueCallback( http_parser * pHttpParser,
                                               const char * pLoc,
                                               size_t length );
  
  /**
   * @brief Callback from http-parser to indicate it reached the end of the headers in the HTTP response messsage.
   *
   * The end of the headers is signalled in a HTTP response message by another "\r\n" after the final header line.
   *
   * See https://github.com/nodejs/http-parser for more information.
   *
   * @param[in] pHttpParser - http-parser state structure.
   *
   * @return 0 to tell http-parser to keep parsing.
   *         1 to tell http-parser that parsing should stop return from http_parser_execute with error HPE_CB_headers_complete.
   */
  static int _httpParserOnHeadersCompleteCallback( http_parser * pHttpParser );
  
  /**
   * @brief Callback from http-parser to indicate it found HTTP response body.
   *
   * This callback will be invoked multiple times if the response body is of "Transfer-Encoding: chunked".
   * _httpParserOnChunkHeaderCallback() will be invoked first, then _httpParserOnBodyCallback(), then
   * _httpParserOnChunkCompleteCallback(), then repeated back to _httpParserOnChunkHeaderCallback() if there are more
   * "chunks".
   *
   * See https://github.com/nodejs/http-parser for more information.
   *
   * @param[in] pHttpParser - http-parser state structure.
   * @param[in] pLoc - Pointer to the body string in the response message buffer.
   * @param[in] length - The length of the body found.
   *
   * @return 0 to tell http-parser to keep parsing.
   *         1 to tell http-parser that parsing should stop return from http_parser_execute with error HPE_CB_body.
   */
  static int _httpParserOnBodyCallback( http_parser * pHttpParser,
                                        const char * pLoc,
                                        size_t length );
  
  /**
   * @brief Callback from http-parser to indicate it reached the end of the HTTP response messsage.
   *
   * The end of the message is signalled in a HTTP response message by another "\r\n" after the final header line, with no
   * entity body; or it is singalled by "\r\n" at the end of the entity body.
   *
   * For a Transfer-Encoding: chunked type of response message, the end of the message is signalled by a terminating
   * chunk header with length zero.
   *
   * See https://github.com/nodejs/http-parser for more information.
   *
   * @param[in] pHttpParser - http-parser state structure.
   *
   * @return 0 to tell http-parser to keep parsing.
   *         1 to tell http-parser that parsing should stop return from http_parser_execute with error HPE_CB_message_complete.
   */
  static int _httpParserOnMessageCompleteCallback( http_parser * pHttpParser );
  
  /* This code prints debugging information and is, therefore, compiled only when
   * log level is set to IOT_LOG_DEBUG. */
  #if ( LIBRARY_LOG_LEVEL == IOT_LOG_DEBUG )
  
  /**
   * @brief Callback from http-parser to indicate it found an HTTP Transfer-Encoding: chunked header.
   *
   * Transfer-Encoding: chunked headers are embedded in the HTTP response entity body by a "\r\n" followed by the size of
   * the chunk followed by another "\r\n".
   *
   * If only part of the header field was returned here in this callback, then this callback will be invoked again the
   * next time the parser executes on the next part of the header field.
   *
   * See https://github.com/nodejs/http-parser for more information.
   *
   * @param[in] pHttpParser - http-parser state structure.
   *
   * @return 0 to tell http-parser to keep parsing.
   *         1 to tell http-parser that parsing should stop return from http_parser_execute with error HPE_CB_chunk_header.
   */
      static int _httpParserOnChunkHeaderCallback( http_parser * pHttpParser );
  
  /**
   * @brief Callback from http-parser to indicate it reached the end of an HTTP response messsage "chunk".
   *
   * A chunk is complete when the chunk header size is read fully in the body.
   *
   * See https://github.com/nodejs/http-parser for more information.
   *
   * @param[in] pHttpParser - http-parser state structure.
   *
   * @return 0 to tell http-parser to keep parsing.
   *         1 to tell http-parser that parsing should stop return from http_parser_execute with error HPE_CB_chunk_complete.
   */
      static int _httpParserOnChunkCompleteCallback( http_parser * pHttpParser );
  #endif
  
  /**
   * @brief Network receive callback for the HTTPS Client library.
   *
   * This function is called by the network layer whenever data is available for the HTTP library.
   *
   * @param[in] pNetworkConnection - The network connection with the HTTPS connection, passed by the network stack.
   * @param[in] pReceiveContext - A pointer to the HTTPS Client connection handle for which the packet was received.
   */
  static void _networkReceiveCallback( void * pNetworkConnection,
                                       void * pReceiveContext );
  
  /**
   * @brief Connects to HTTPS server and initializes the connection context.
   *
   * @param[out] pConnHandle - The out parameter to return handle representing the open connection.
   * @param[in] pConnInfo - The connection configuration.
   *
   * @return #IOT_HTTPS_OK if the connection context initialization was successful.
   *         #IOT_HTTPS_CONNECTION_ERROR if the connection failed.
   *         #IOT_HTTPS_INTERNAL_ERROR if the context initialization failed.
   */
  static IotHttpsReturnCode_t _createHttpsConnection( IotHttpsConnectionHandle_t * pConnHandle,
                                                      IotHttpsConnectionInfo_t * pConnInfo );
  
  /**
   * @brief Disconnects from the network.
   *
   * @param[in] pHttpsConnection - HTTPS connection handle.
   */
  static void _networkDisconnect( _httpsConnection_t * pHttpsConnection );
  
  /**
   * @brief Destroys the network connection.
   *
   * @param[in] pHttpsConnection - HTTPS connection handle.
   */
  static void _networkDestroy( _httpsConnection_t * pHttpsConnection );
  
  /**
   * @brief Add a header to the current HTTP request.
   *
   * The headers are stored in reqHandle->pHeaders.
   *
   * @param[in] pHttpsRequest - HTTP request context.
   * @param[in] pName - The name of the header to add.
   * @param[in] nameLen - The length of the header name string.
   * @param[in] pValue - The buffer containing the value string.
   * @param[in] valueLen - The length of the header value string.
   *
   * @return #IOT_HTTPS_OK if the header was added to the request successfully.
   *         #IOT_HTTPS_INSUFFICIENT_MEMORY if there was not enough room in the IotHttpsRequestHandle_t->pHeaders.
   */
  static IotHttpsReturnCode_t _addHeader( _httpsRequest_t * pHttpsRequest,
                                          const char * pName,
                                          uint32_t nameLen,
                                          const char * pValue,
                                          uint32_t valueLen );
  
  /**
   * @brief Send data on the network.
   *
   * @param[in] pHttpsConnection - HTTP connection context.
   * @param[in] pBuf - The buffer containing the data to send.
   * @param[in] len - The length of the data to send.
   *
   * @return #IOT_HTTPS_OK if the data sent successfully.
   *         #IOT_HTTPS_NETWORK_ERROR if there was an error sending the data on the network.
   */
  static IotHttpsReturnCode_t _networkSend( _httpsConnection_t * pHttpsConnection,
                                            uint8_t * pBuf,
                                            size_t len );
  
  /**
   * @brief Receive data on the network.
   *
   * @param[in] pHttpsConnection - HTTP connection context.
   * @param[in] pBuf - The buffer to receive the data into.
   * @param[in] bufLen - The length of the data to receive.
   * @param[in] numBytesRecv - The number of bytes read from the network.
   *
   * @return #IOT_HTTPS_OK if the data was received successfully.
   *         #IOT_HTTPS_NETWORK_ERROR if we timedout trying to receive data from the network.
   */
  static IotHttpsReturnCode_t _networkRecv( _httpsConnection_t * pHttpsConnection,
                                            uint8_t * pBuf,
                                            size_t bufLen,
                                            size_t * numBytesRecv );
  
  /**
   * @brief Send all of the HTTP request headers in the pHeadersBuf and the final Content-Length and Connection headers.
   *
   * All of the headers in headerbuf are sent first followed by the computed content length and persistent connection
   * indication.
   *
   * @param[in] pHttpsConnection - HTTP connection context.
   * @param[in] pHeadersBuf - The buffer containing the request headers to send. This buffer must contain HTTP headers
   *            lines without the indicator for the the end of the HTTP headers.
   * @param[in] headersLength - The length of the request headers to send.
   * @param[in] isNonPersistent - Indicator of whether the connection is persistent or not.
   * @param[in] contentLength - The length of the request body used for automatically creating a "Content-Length" header.
   *
   * @return #IOT_HTTPS_OK if the headers were fully sent successfully.
   *         #IOT_HTTPS_NETWORK_ERROR if there was an error receiving the data on the network.
   */
  static IotHttpsReturnCode_t _sendHttpsHeaders( _httpsConnection_t * pHttpsConnection,
                                                 uint8_t * pHeadersBuf,
                                                 uint32_t headersLength,
                                                 bool isNonPersistent,
                                                 uint32_t contentLength );
  
  /**
   * @brief Send all of the HTTP request body in pBodyBuf.
   *
   * @param[in] pHttpsConnection - HTTP connection context.
   * @param[in] pBodyBuf - Buffer of the request body to send.
   * @param[in] bodyLength - The length of the body to send.
   *
   * @return #IOT_HTTPS_OK if the body was fully sent successfully.
   *         #IOT_HTTPS_NETWORK_ERROR if there was an error receiving the data on the network.
   */
  static IotHttpsReturnCode_t _sendHttpsBody( _httpsConnection_t * pHttpsConnection,
                                              uint8_t * pBodyBuf,
                                              uint32_t bodyLength );
  
  /**
   * @brief Parse the HTTP response message in pBuf.
   *
   * @param[in] pHttpParserInfo - Pointer to the information containing the instance of the http-parser and the execution function.
   * @param[in] pBuf - The buffer containing the data to parse.
   * @param[in] len - The length of data to parse.
   *
   * @return #IOT_HTTPS_OK if the data was parsed successfully.
   *         #IOT_HTTPS_PARSING_ERROR if there was an error with parsing the data.
   */
  static IotHttpsReturnCode_t _parseHttpsMessage( _httpParserInfo_t * pHttpParserInfo,
                                                  char * pBuf,
                                                  size_t len );
  
  /**
   * @brief Receive any part of an HTTP response.
   *
   * This function is used for both receiving the body into the body buffer and receiving the header into the header
   * buffer.
   *
   * @param[in] pHttpsConnection - HTTP Connection context.
   * @param[in] pParser - Pointer to the instance of the http-parser.
   * @param[in] pCurrentParserState - The current state of what has been parsed in the HTTP response.
   * @param[in] finalParserState - The final state of the parser expected after this function finishes.
   * @param[in] currentBufferProcessingState - The current buffer that is the HTTPS message is being received into.
   * @param[in] pBufCur - Pointer to the next location to write data into the buffer pBuf. This is a double pointer to update the response context buffer pointers.
   * @param[in] pBufEnd - Pointer to the end of the buffer to receive the HTTP response into.
   *
   * @return #IOT_HTTPS_OK if we received the HTTP response message part successfully.
   *         #IOT_HTTPS_PARSING_ERROR if there was an error with parsing the data.
   *         #IOT_HTTPS_NETWORK_ERROR if there was an error receiving the data on the network.
   */
  static IotHttpsReturnCode_t _receiveHttpsMessage( _httpsConnection_t * pHttpsConnection,
                                                    _httpParserInfo_t * pParser,
                                                    IotHttpsResponseParserState_t * pCurrentParserState,
                                                    IotHttpsResponseParserState_t finalParserState,
                                                    IotHttpsResponseBufferState_t currentBufferProcessingState,
                                                    uint8_t ** pBufCur,
                                                    uint8_t ** pBufEnd );
  
  /**
   * @brief Receive the HTTP response headers.
   *
   * Receiving the response headers is always the first step in receiving the response, therefore the
   * pHttpsResponse->httpParserInfo will be initialized to a starting state when this function is called.
   *
   * This function also sets internal states to indicate that the header buffer is being processed now for a new response.
   *
   * @param[in] pHttpsConnection - HTTP connection context.
   * @param[in] pHttpsResponse - HTTP response context.
   *
   * @return #IOT_HTTPS_OK if we received the HTTP headers successfully.
   *         #IOT_HTTPS_PARSING_ERROR if there was an error with parsing the header buffer.
   *         #IOT_HTTPS_NETWORK_ERROR if there was an error receiving the data on the network.
   */
  static IotHttpsReturnCode_t _receiveHttpsHeaders( _httpsConnection_t * pHttpsConnection,
                                                    _httpsResponse_t * pHttpsResponse );
  
  /**
   * @brief Receive the HTTP response body.
   *
   * Sets internal states to indicate that the the body buffer is being processed now for a new response.
   *
   * @param[in] pHttpsConnection - HTTP connection context.
   * @param[in] pHttpsResponse - HTTP response context.
   *
   * @return #IOT_HTTPS_OK if we received the HTTP body successfully.
   *         #IOT_HTTPS_PARSING_ERROR if there was an error with parsing the body buffer.
   *         #IOT_HTTPS_NETWORK_ERROR if there was an error receiving the data on the network.
   */
  static IotHttpsReturnCode_t _receiveHttpsBody( _httpsConnection_t * pHttpsConnection,
                                                 _httpsResponse_t * pHttpsResponse );
  
  /**
   * @brief Read the rest of any HTTP response that may be on the network.
   *
   * This reads the rest of any left over response data that might still be on the network buffers. We do not want this
   * data left over because it will spill into the header and body buffers of next response that we try to receive.
   *
   * If we performed a request without a body and the headers received exceeds the size of the
   * pHttpsResponse->pHeaders buffer, then we need to flush the network buffer.
   *
   * If the application configured the body buffer as null in IotHttpsResponseInfo_t.syncInfo.respData and the server
   * sends body in the response, but it exceeds the size of  pHttpsResponse->pHeaders buffer, then we need to flush the
   * network buffer.
   *
   * If the amount of body received on the network does not fit into a non-null IotHttpsResponseInfo_t.syncInfo.respData,
   * then we need to flush the network buffer.
   *
   * If an asynchronous request cancels in the middle of a response process, after already sending the request message,
   * then we need to flush the network buffer.
   *
   * @param[in] pHttpsConnection - HTTP connection context.
   * @param[in] pHttpsResponse - HTTP response context.
   *
   * @return #IOT_HTTPS_OK if we successfully flushed the network data.
   *         #IOT_HTTPS_PARSING_ERROR if there was an error with parsing the data.
   *         #IOT_HTTPS_NETWORK_ERROR if there was an error receiving the data on the network.
   */
  static IotHttpsReturnCode_t _flushHttpsNetworkData( _httpsConnection_t * pHttpsConnection,
                                                      _httpsResponse_t * pHttpsResponse );
  
  /**
   * @brief Task pool job routine to send the HTTP request within the pUserContext.
   *
   * @param[in] pTaskPool Pointer to the system task pool.
   * @param[in] pJob Pointer the to the HTTP request sending job.
   * @param[in] pUserContext Pointer to an HTTP request, passed as an opaque context.
   */
  static void _sendHttpsRequest( IotTaskPool_t pTaskPool,
                                 IotTaskPoolJob_t pJob,
                                 void * pUserContext );
  
  
  /**
   * @brief Receive the HTTPS body specific to an asynchronous type of response.
   *
   * @param[in] pHttpsResponse - HTTP response context.
   *
   * @return  #IOT_HTTPS_OK - If the the response body was received with no issues.
   *          #IOT_HTTPS_RECEIVE_ABORT - If the request was cancelled by the Application
   *          #IOT_HTTPS_PARSING_ERROR - If there was an issue parsing the HTTP response body.
   *          #IOT_HTTPS_NETWORK_ERROR if there was an error receiving the data on the network.
   */
  static IotHttpsReturnCode_t _receiveHttpsBodyAsync( _httpsResponse_t * pHttpsResponse );
  
  /**
   * @brief Receive the HTTPS body specific to a synchronous type of response.
   *
   * @param[in] pHttpsResponse - HTTP response context.
   *
   * @return  #IOT_HTTPS_OK - If the the response body was received with no issues.
   *          #IOT_HTTPS_MESSAGE_TOO_LARGE - If the body from the network is too large to fit into the configured body buffer.
   *          #IOT_HTTPS_PARSING_ERROR - If there was an issue parsing the HTTP response body.
   *          #IOT_HTTPS_NETWORK_ERROR if there was an error receiving the data on the network.
   */
  static IotHttpsReturnCode_t _receiveHttpsBodySync( _httpsResponse_t * pHttpsResponse );
  
  /**
   * @brief Schedule the task to send the the HTTP request.
   *
   * @param[in] pHttpsRequest - HTTP request context.
   *
   * @return  #IOT_HTTPS_OK - If the task to send the HTTP request was successfully scheduled.
   *          #IOT_HTTPS_INTERNAL_ERROR - If a taskpool job could not be created.
   *          #IOT_HTTPS_ASYNC_SCHEDULING_ERROR - If there was an error scheduling the job.
   */
  IotHttpsReturnCode_t _scheduleHttpsRequestSend( _httpsRequest_t * pHttpsRequest );
  
  /**
   * @brief Add the request to the connection's request queue.
   *
   * This will schedule a task if the request is first and only request in the queue.
   *
   * @param[in] pHttpsRequest - HTTP request context.
   *
   * @return  #IOT_HTTPS_OK - If the request was successfully added to the connection's request queue.
   *          #IOT_HTTPS_INTERNAL_ERROR - If a taskpool job could not be created.
   *          #IOT_HTTPS_ASYNC_SCHEDULING_ERROR - If there was an error scheduling the job.
   */
  IotHttpsReturnCode_t _addRequestToConnectionReqQ( _httpsRequest_t * pHttpsRequest );
  
  /**
   * @brief Cancel the HTTP request's processing.
   *
   * pHttpsRequest->cancelled will be checked and the request cancelled if specified so at the following intervals:
   *  - Before sending the HTTPS headers at the start of the scheduled sending of the HTTPS request.
   *  - After Sending the HTTPS headers.
   *  - After Sending the HTTPS body.
   *
   * @param[in] pHttpsRequest - HTTP request context.
   */
  static void _cancelRequest( _httpsRequest_t * pHttpsRequest );
  
  /**
   * @brief Cancel the HTTP response's processing.
   *
   * pHttpsResponse->cancelled will be checked and the response cancelled if specified so at the following intervals:
   *  - At the start of the network receive callback.
   *  - After receiving the HTTPS headers.
   *  - After Receiving the HTTPS body.
   *
   * @param[in] pHttpsResponse - HTTP response context.
   */
  static void _cancelResponse( _httpsResponse_t * pHttpsResponse );
  
  /**
   * @brief Initialize the input pHttpsResponse with pRespInfo.
   *
   * @param[in] pRespHandle - Non-null HTTP response context.
   * @param[in] pRespInfo - Response configuration information.
   * @param[in] pHttpsRequest - HTTP request to grab async information, persistence, and method from.
   */
  static IotHttpsReturnCode_t _initializeResponse( IotHttpsResponseHandle_t * pRespHandle,
                                                   IotHttpsResponseInfo_t * pRespInfo,
                                                   _httpsRequest_t * pHttpsRequest );
  
  /**
   * @brief Increment the pointer stored in pBufCur depending on the character found in there.
   *
   * This function increments the pHeadersCur pointer further if the message ended with a header line delimitter.
   *
   * @param[in] pBufCur - Pointer to the next location to write data into the buffer pBuf. This is a double pointer to update the response context buffer pointers.
   * @param[in] pBufEnd - Pointer to the end of the buffer to receive the HTTP response into.
   */
  static void _incrementNextLocationToWriteBeyondParsed( uint8_t ** pBufCur,
                                                         uint8_t ** pBufEnd );
  
  /**
   * @brief Send the HTTPS headers and body referenced in pHttpsRequest.
   *
   * Sends both the headers and body over the network.
   *
   * @param[in] pHttpsConnection - HTTPS connection context.
   * @param[in] pHttpsRequest - HTTPS request context.
   */
  static IotHttpsReturnCode_t _sendHttpsHeadersAndBody( _httpsConnection_t * pHttpsConnection,
                                                        _httpsRequest_t * pHttpsRequest );
  
  /*-----------------------------------------------------------*/
  
  /**
   * @brief Definition of the http-parser settings.
   *
   * The http_parser_settings holds all of the callbacks invoked by the http-parser.
   */
  static http_parser_settings _httpParserSettings = { 0 };
  
  /*-----------------------------------------------------------*/
  
  static int _httpParserOnMessageBeginCallback( http_parser * pHttpParser )
  {
      int retVal = KEEP_PARSING;
  
      IotLogDebug( "Parser: Start of HTTPS Response message." );
  
      _httpsResponse_t * pHttpsResponse = ( _httpsResponse_t * ) ( pHttpParser->data );
      /* Set the state of the parser. The headers are at the start of the message always. */
      pHttpsResponse->parserState = PARSER_STATE_IN_HEADERS;
      return retVal;
  }
  
  /*-----------------------------------------------------------*/
  
  static int _httpParserOnStatusCallback( http_parser * pHttpParser,
                                          const char * pLoc,
                                          size_t length )
  {
      _httpsResponse_t * pHttpsResponse = ( _httpsResponse_t * ) ( pHttpParser->data );
  
      IotLogDebug( "Parser: Status %.*s retrieved from HTTPS response.", length, pLoc );
  
      /* Save the status code so it can be retrieved with IotHttpsClient_ReadResponseStatus(). */
      pHttpsResponse->status = ( uint16_t ) ( pHttpParser->status_code );
  
      /* If we are parsing the network data received in the header buffer then we
       * increment pHttpsResponse->pHeadersCur. The status line in the response is
       * part of the data stored in header buffer _httpResponse->pHeaders. */
      if( pHttpsResponse->bufferProcessingState == PROCESSING_STATE_FILLING_HEADER_BUFFER )
      {
          /* pHeadersCur will never exceed the pHeadersEnd here because PROCESSING_STATE_FILLING_HEADER_BUFFER
           * indicates we are currently in the header buffer and the total size of the header buffer is passed
           * into http_parser_execute() as the maximum length to parse. */
          pHttpsResponse->pHeadersCur = ( uint8_t * ) ( pLoc += length );
      }
  
      return KEEP_PARSING;
  }
  
  /*-----------------------------------------------------------*/
  
  static int _httpParserOnHeaderFieldCallback( http_parser * pHttpParser,
                                               const char * pLoc,
                                               size_t length )
  {
      IotLogDebug( "Parser: HTTPS header field parsed %.*s", length, pLoc );
  
      _httpsResponse_t * pHttpsResponse = ( _httpsResponse_t * ) ( pHttpParser->data );
  
      /* If we are parsing the network data received in the header buffer then we can increment
       * pHttpsResponse->pHeadersCur. */
      if( pHttpsResponse->bufferProcessingState == PROCESSING_STATE_FILLING_HEADER_BUFFER )
      {
          pHttpsResponse->pHeadersCur = ( uint8_t * ) ( pLoc += length );
      }
  
      /* If the IotHttpsClient_ReadHeader() was called, then we check for the header field of interest. */
      if( pHttpsResponse->bufferProcessingState == PROCESSING_STATE_SEARCHING_HEADER_BUFFER )
      {
          if( pHttpsResponse->readHeaderFieldLength != length )
          {
              pHttpsResponse->foundHeaderField = false;
          }
          else if( strncmp( pHttpsResponse->pReadHeaderField, pLoc, length ) == 0 )
          {
              pHttpsResponse->foundHeaderField = true;
          }
      }
  
      return KEEP_PARSING;
  }
  
  /*-----------------------------------------------------------*/
  
  static int _httpParserOnHeaderValueCallback( http_parser * pHttpParser,
                                               const char * pLoc,
                                               size_t length )
  {
      int retVal = KEEP_PARSING;
  
      IotLogDebug( "Parser: HTTPS header value parsed %.*s", length, pLoc );
      _httpsResponse_t * pHttpsResponse = ( _httpsResponse_t * ) ( pHttpParser->data );
  
      /* If we are parsing the network data received in the header buffer then we can increment
       * pHttpsResponse->pHeadersCur. */
      if( pHttpsResponse->bufferProcessingState == PROCESSING_STATE_FILLING_HEADER_BUFFER )
      {
          pHttpsResponse->pHeadersCur = ( uint8_t * ) ( pLoc += length );
      }
  
      /* If the IotHttpsClient_ReadHeader() was called, then we check if we found the header field of interest. */
      if( pHttpsResponse->bufferProcessingState == PROCESSING_STATE_SEARCHING_HEADER_BUFFER )
      {
          if( pHttpsResponse->foundHeaderField )
          {
              pHttpsResponse->pReadHeaderValue = ( char * ) ( pLoc );
              pHttpsResponse->readHeaderValueLength = length;
              /* We found a header field so we don't want to keep parsing.*/
              retVal = STOP_PARSING;
          }
      }
  
      return retVal;
  }
  
  /*-----------------------------------------------------------*/
  
  static int _httpParserOnHeadersCompleteCallback( http_parser * pHttpParser )
  {
      IotLogDebug( "Parser: End of the headers reached." );
  
      int retVal = KEEP_PARSING;
      _httpsResponse_t * pHttpsResponse = ( _httpsResponse_t * ) ( pHttpParser->data );
      pHttpsResponse->parserState = PARSER_STATE_HEADERS_COMPLETE;
  
      /* If the IotHttpsClient_ReadHeader() was called, we return after finishing looking through all of the headers.
       * Returning a non-zero value exits the http parsing. */
      if( pHttpsResponse->bufferProcessingState == PROCESSING_STATE_SEARCHING_HEADER_BUFFER )
      {
          retVal = STOP_PARSING;
      }
  
      /* When in this callback the pHeaderCur pointer is at the first "\r" in the last header line. HTTP/1.1
       * headers end with another "\r\n" at the end of the last line. This means we must increment
       * the headerCur pointer to the length of "\r\n\r\n". */
      if( pHttpsResponse->bufferProcessingState == PROCESSING_STATE_FILLING_HEADER_BUFFER )
      {
          pHttpsResponse->pHeadersCur += ( 2 * HTTPS_END_OF_HEADER_LINES_INDICATOR_LENGTH );
      }
  
      if( pHttpsResponse->bufferProcessingState < PROCESSING_STATE_FINISHED )
      {
          /* For a HEAD method, there is no body expected in the response, so we return 1 to skip body parsing. */
          if( ( pHttpsResponse->method == IOT_HTTPS_METHOD_HEAD ) )
          {
              retVal = STOP_PARSING;
  
              /* Since the message is considered complete now for a HEAD response, then we set the parser state
               * to the completed state. */
              pHttpsResponse->parserState = PARSER_STATE_BODY_COMPLETE;
          }
  
          /* If this is NOT a HEAD method and there is body configured, but the server does not send a body in the
           * response, then the body buffer will be filled with the zeros from rest of the header buffer. http-parser
           * will invoke the on_body callback and consider the zeros following the headers as body. */
  
          /* If there is not body configured for a synchronous reponse, we do not stop the parser from continueing. */
  
          /* Skipping the body will cause the parser to invoke the _httpParserOnMessageComplete() callback. This is
           * not desired when there is actaully HTTP response body sent by the server because this will set the parser
           * state to PARSER_STATE_BODY_COMPLETE. If this state is set then the rest of possible body will not be
           * flushed out. The network flush looks for the state being PARSER_STATE_BODY_COMPLETE to finish flushing. */
      }
  
      return retVal;
  }
  
  /*-----------------------------------------------------------*/
  
  static int _httpParserOnBodyCallback( http_parser * pHttpParser,
                                        const char * pLoc,
                                        size_t length )
  {
      IotLogDebug( "Parser: Reached the HTTPS message body. It is of length: %d", length );
  
      _httpsResponse_t * pHttpsResponse = ( _httpsResponse_t * ) ( pHttpParser->data );
      pHttpsResponse->parserState = PARSER_STATE_IN_BODY;
  
      /* If the header buffer is currently being processed, but HTTP response body was found, then for an asynchronous
       * request this if-case saves where the body is located. In the asynchronous case, the body buffer is not available
       * until the readReadyCallback is invoked, which happens after the headers are processed.  */
      if( ( pHttpsResponse->bufferProcessingState == PROCESSING_STATE_FILLING_HEADER_BUFFER ) && ( pHttpsResponse->isAsync ) )
      {
          /* For an asynchronous response, the buffer to store the body will be available after the headers
           * are read first. We may receive part of the body in the header buffer. We will want to leave this here
           * and copy it over when the body buffer is available in the _readReadyCallback().
           */
          if( pHttpsResponse->pBodyInHeaderBuf == NULL )
          {
              pHttpsResponse->pBodyInHeaderBuf = ( uint8_t * ) ( pLoc );
              pHttpsResponse->pBodyCurInHeaderBuf = pHttpsResponse->pBodyInHeaderBuf;
          }
  
          /* If there is a chunk encoded body in the header buffer, we will want to overwrite the chunk headers with the
           * actual body. This is so that when the application calls IotHttpsClient_ReadResponseBody(), in the
           * readReadyCallback(), we can pass the body into the body buffer provided right away. */
          if( pHttpsResponse->pBodyCurInHeaderBuf != ( uint8_t * ) pLoc )
          {
              memcpy( pHttpsResponse->pBodyCurInHeaderBuf, pLoc, length );
          }
  
          pHttpsResponse->pBodyCurInHeaderBuf += length;
      }
      else if( pHttpsResponse->bufferProcessingState < PROCESSING_STATE_FINISHED )
      {
          /* Has the user provided a buffer and is it large enough to fit the body? The
           * case of body buffer not being large enough can happen if the body was received
           * in the header buffer and the body buffer can not fit in all the body. */
          if( ( pHttpsResponse->pBodyCur != NULL ) && ( pHttpsResponse->pBodyEnd - pHttpsResponse->pBodyCur > 0 ) )
          {
              /* There are two scenarios when we need to copy data around:
               * 1. Some or all of the response body may have been received in the header
               * buffer. If that is the case, we copy the response body received in the
               * header buffer to the user provided body buffer.
               * 2. When we receive chunked header, the actual body is separated in
               * multiple chunks which are preceeded by length. For example, a chunked
               * body may look like:
               *
               * 7\r\n
               * Mozilla\r\n
               * 9\r\n
               * Developer\r\n
               * 7\r\n
               * Network\r\n
               * 0\r\n
               * \r\n
               *
               * In this case, we want the parsed body buffer to contain actual body only
               * (MozillaDeveloperNetwork in the above example).
               */
  
              /* If the response body found by the parser (pLoc) is not equal to the
               * current writable location in the body buffer (_httpsResponse->pBodyCur),
               * it indicates that:
               * - Either the data is in the header buffer and needs to be copied into the
               * body buffer.
               * - Or it is a chunked response and the data needs to be moved up in the
               * body buffer. */
              if( ( pHttpsResponse->pBodyCur + length ) <= pHttpsResponse->pBodyEnd )
              {
                  if( pHttpsResponse->pBodyCur != ( uint8_t * ) pLoc )
                  {
                      memcpy( pHttpsResponse->pBodyCur, pLoc, length );
                  }
  
                  pHttpsResponse->pBodyCur += length;
              }
          }
      }
  
      return KEEP_PARSING;
  }
  
  /*-----------------------------------------------------------*/
  
  static int _httpParserOnMessageCompleteCallback( http_parser * pHttpParser )
  {
      IotLogDebug( "Parser: End of the HTTPS message reached." );
  
      _httpsResponse_t * pHttpsResponse = ( _httpsResponse_t * ) ( pHttpParser->data );
      pHttpsResponse->parserState = PARSER_STATE_BODY_COMPLETE;
  
      /* This callback is invoked when the complete HTTP response has been received.
       * We tell the parser to parse the whole body buffer as opposed to the size of
       * the response body. For example, if the size of the body buffer is 1000 but
       * the size of the actual body is 500, we tell the parser to parse the whole
       * buffer of length 1000. We do zero out the buffer in the beginning so that all
       * the buffer after the actual body contains zeros. We return greater than zero to stop parsing
       * since the end of the HTTP message has been reached. Any data beyond the end of the message is
       * ignored. */
      return STOP_PARSING;
  }
  
  /*-----------------------------------------------------------*/
  
  /* This code prints debugging information and is, therefore, compiled only when
   * log level is set to IOT_LOG_DEBUG. */
  #if ( LIBRARY_LOG_LEVEL == IOT_LOG_DEBUG )
      static int _httpParserOnChunkHeaderCallback( http_parser * pHttpParser )
      {
          ( void ) pHttpParser;
          IotLogDebug( "Parser: HTTPS message Chunked encoding header callback." );
          IotLogDebug( "Parser: HTTPS message Chunk size: %d", pHttpParser->content_length );
          return 0;
      }
  
  /*-----------------------------------------------------------*/
  
      static int _httpParserOnChunkCompleteCallback( http_parser * pHttpParser )
      {
          ( void ) pHttpParser;
          IotLogDebug( "End of a HTTPS message Chunk complete callback." );
          return 0;
      }
  #endif /* if ( LIBRARY_LOG_LEVEL == IOT_LOG_DEBUG ) */
  
  /*-----------------------------------------------------------*/
  
  static IotHttpsReturnCode_t _receiveHttpsBodyAsync( _httpsResponse_t * pHttpsResponse )
  {
      HTTPS_FUNCTION_ENTRY( IOT_HTTPS_OK );
  
      if( pHttpsResponse->pCallbacks->readReadyCallback )
      {
          /* If there is still more body that has not been passed back to the user, then this callback is invoked again. */
          do
          {
              IotLogDebug( "Invoking the readReadyCallback." );
              pHttpsResponse->pCallbacks->readReadyCallback( pHttpsResponse->pUserPrivData,
                                                             pHttpsResponse,
                                                             pHttpsResponse->bodyRxStatus,
                                                             pHttpsResponse->status );
  
              if( pHttpsResponse->cancelled == true )
              {
                  IotLogDebug( "Cancelled HTTP response %d.", pHttpsResponse );
                  status = IOT_HTTPS_RECEIVE_ABORT;
  
                  /* We break out of the loop and do not goto clean up because we want to print debugging logs for
                   * the parser state and the networks status. */
                  break;
              }
          } while( ( pHttpsResponse->parserState < PARSER_STATE_BODY_COMPLETE ) && ( pHttpsResponse->bodyRxStatus == IOT_HTTPS_OK ) );
  
          if( HTTPS_FAILED( pHttpsResponse->bodyRxStatus ) )
          {
              IotLogError( "Error receiving the HTTP response body for response %d. Error code: %d",
                           pHttpsResponse,
                           pHttpsResponse->bodyRxStatus );
              /* An error in the network or the parser takes precedence  */
              status = pHttpsResponse->bodyRxStatus;
          }
  
          if( pHttpsResponse->parserState < PARSER_STATE_BODY_COMPLETE )
          {
              IotLogDebug( "Did not receive all of the HTTP response body for response %d.",
                           pHttpsResponse );
          }
      }
  
      /* This GOTO cleanup is here for compiler warnings about using HTTPS_FUNCTION_EXIT_NO_CLEANUP() without a
       * corresponding goto. */
      HTTPS_GOTO_CLEANUP();
      HTTPS_FUNCTION_EXIT_NO_CLEANUP();
  }
  
  /*-----------------------------------------------------------*/
  
  static IotHttpsReturnCode_t _receiveHttpsBodySync( _httpsResponse_t * pHttpsResponse )
  {
      HTTPS_FUNCTION_ENTRY( IOT_HTTPS_OK );
      _httpsConnection_t * pHttpsConnection = pHttpsResponse->pHttpsConnection;
  
      /* The header buffer is now filled or the end of the headers has been reached already. If part of the response
       *  body was read from the network into the header buffer, then it was already copied to the body buffer in the
       *  _httpParserOnBodyCallback(). */
      if( pHttpsResponse->pBody != NULL )
      {
          /* If there is room left in the body buffer and we have not received the whole response body,
           * then try to receive more. */
          if( ( ( pHttpsResponse->pBodyEnd - pHttpsResponse->pBodyCur ) > 0 ) &&
              ( pHttpsResponse->parserState < PARSER_STATE_BODY_COMPLETE ) )
          {
              status = _receiveHttpsBody( pHttpsConnection,
                                          pHttpsResponse );
  
              if( HTTPS_FAILED( status ) )
              {
                  IotLogError( "Error receiving the HTTPS response body for response %d. Error code: %d.",
                               pHttpsResponse,
                               status );
                  HTTPS_GOTO_CLEANUP();
              }
          }
          else
          {
              IotLogDebug( "Received the maximum amount of HTTP body when filling the header buffer for response %d.",
                           pHttpsResponse );
          }
  
          /* If we don't reach the end of the HTTPS body in the parser, then we only received part of the body.
           *  The rest of body will be on the network socket. */
          if( HTTPS_SUCCEEDED( status ) && ( pHttpsResponse->parserState < PARSER_STATE_BODY_COMPLETE ) )
          {
              IotLogError( "HTTPS response body does not fit into application provided response buffer at location 0x%x "
                           "with length: %d",
                           pHttpsResponse->pBody,
                           pHttpsResponse->pBodyEnd - pHttpsResponse->pBody );
              HTTPS_SET_AND_GOTO_CLEANUP( IOT_HTTPS_MESSAGE_TOO_LARGE );
          }
      }
      else
      {
          IotLogDebug( "No response body was configure for response %d.", pHttpsResponse );
      }
  
      HTTPS_FUNCTION_EXIT_NO_CLEANUP();
  }
  
  /*-----------------------------------------------------------*/
  
  static void _networkReceiveCallback( void * pNetworkConnection,
                                       void * pReceiveContext )
  {
      HTTPS_FUNCTION_ENTRY( IOT_HTTPS_OK );
  
      IotHttpsReturnCode_t flushStatus = IOT_HTTPS_OK;
      IotHttpsReturnCode_t disconnectStatus = IOT_HTTPS_OK;
      IotHttpsReturnCode_t scheduleStatus = IOT_HTTPS_OK;
      _httpsConnection_t * pHttpsConnection = ( _httpsConnection_t * ) pReceiveContext;
      _httpsResponse_t * pCurrentHttpsResponse = NULL;
      _httpsRequest_t * pNextHttpsRequest = NULL;
      IotLink_t * pQItem = NULL;
      bool fatalDisconnect = false;
  
      /* The network connection is already in the connection context. */
      ( void ) pNetworkConnection;
  
      /* Get the response from the response queue. */
      IotMutex_Lock( &( pHttpsConnection->connectionMutex ) );
      pQItem = IotDeQueue_PeekHead( &( pHttpsConnection->respQ ) );
      IotMutex_Unlock( &( pHttpsConnection->connectionMutex ) );
  
      /* If the receive callback is invoked and there is no response expected, then this a violation of the HTTP/1.1
       * protocol. */
      if( pQItem == NULL )
      {
          IotLogError( "Received data on the network, when no response was expected..." );
          fatalDisconnect = true;
          HTTPS_SET_AND_GOTO_CLEANUP( IOT_HTTPS_NETWORK_ERROR );
      }
  
      /* Set the current HTTP response context to use. */
      pCurrentHttpsResponse = IotLink_Container( _httpsResponse_t, pQItem, link );
  
      /* If the receive callback has invoked, but the request associated with this response has not finished sending
       * to the server, then this is a violation of the HTTP/1.1 protocol.  */
      if( pCurrentHttpsResponse->reqFinishedSending == false )
      {
          IotLogError( "Received response data on the network when the request was not finished sending. This is unexpected." );
          fatalDisconnect = true;
          HTTPS_SET_AND_GOTO_CLEANUP( IOT_HTTPS_NETWORK_ERROR );
      }
  
      /* If the current response was cancelled, then don't bother receiving the headers and body. */
      if( pCurrentHttpsResponse->cancelled )
      {
          IotLogDebug( "Response ID: %d was cancelled.", pCurrentHttpsResponse );
          HTTPS_SET_AND_GOTO_CLEANUP( IOT_HTTPS_RECEIVE_ABORT );
      }
  
      /* Reset the http-parser state to an initial state. This is done so that a new response can be parsed from the
       * beginning. */
      pCurrentHttpsResponse->parserState = PARSER_STATE_NONE;
  
      /* Receive the response from the network. */
      /* Receive the headers first. */
      status = _receiveHttpsHeaders( pHttpsConnection, pCurrentHttpsResponse );
  
      if( HTTPS_FAILED( status ) )
      {
          if( status == IOT_HTTPS_PARSING_ERROR )
          {
              /* There was an error parsing the HTTPS response body. This may be an indication of a server that does
               *  not adhere to protocol correctly. We should disconnect. */
              IotLogError( "Failed to parse the HTTPS headers for response %d, Error code: %d.",
                           pCurrentHttpsResponse,
                           status );
              fatalDisconnect = true;
          }
          else if( status == IOT_HTTPS_NETWORK_ERROR )
          {
              /* Given the function signature of IotNetworkInterface_t.receive, we can only receive 0 to the number of bytes
               * requested. Receiving less than the number of bytes requests is OK since we do not how much data is expected, so
               * we ask for the full size of the receive buffer. Thereofore, the only error that can be returned from receiving
               * the headers or body is a timeout. We always disconnect from the network when there is a timeout because the
               * server may be slow to respond. If the server happens to send the response later at the same time another response
               * is waiting in the queue, then the workflow is corrupted. Pipelining is not current supported in this library. */
              IotLogError( "Network error receiving the HTTPS headers for response %d. Error code: %d",
                           pCurrentHttpsResponse,
                           status );
              fatalDisconnect = true;
          }
          else /* Any other error. */
          {
              IotLogError( "Failed to retrive the HTTPS body for response %d. Error code: %d", pCurrentHttpsResponse, status );
          }
  
          HTTPS_GOTO_CLEANUP();
      }
  
      /* Check if we received all of the headers into the header buffer. */
      if( pCurrentHttpsResponse->parserState < PARSER_STATE_HEADERS_COMPLETE )
      {
          IotLogDebug( "Headers received on the network did not all fit into the configured header buffer for response %d."
                       " The length of the headers buffer is: %d",
                       pCurrentHttpsResponse,
                       pCurrentHttpsResponse->pHeadersEnd - pCurrentHttpsResponse->pHeaders );
          /* It is not error if the headers did not all fit into the buffer. */
      }
  
      /* Receive the body. */
      if( pCurrentHttpsResponse->isAsync )
      {
          status = _receiveHttpsBodyAsync( pCurrentHttpsResponse );
      }
      else
      {
          /* Otherwise receive synchronously. */
          status = _receiveHttpsBodySync( pCurrentHttpsResponse );
      }
  
      if( HTTPS_FAILED( status ) )
      {
          if( status == IOT_HTTPS_RECEIVE_ABORT )
          {
              /* If the request was cancelled, this is logged, but does not close the connection. */
              IotLogDebug( "User cancelled during the async readReadyCallback() for response %d.",
                           pCurrentHttpsResponse );
          }
          else if( status == IOT_HTTPS_PARSING_ERROR )
          {
              /* There was an error parsing the HTTPS response body. This may be an indication of a server that does
               *  not adhere to protocol correctly. We should disconnect. */
              IotLogError( "Failed to parse the HTTPS body for response %d, Error code: %d.",
                           pCurrentHttpsResponse,
                           status );
              fatalDisconnect = true;
          }
          else if( status == IOT_HTTPS_NETWORK_ERROR )
          {
              /* We walways disconnect for a network error because failure to receive the HTTPS body will result in a
               * corruption of the workflow. */
              IotLogError( "Network error receiving the HTTPS body for response %d. Error code: %d",
                           pCurrentHttpsResponse,
                           status );
              fatalDisconnect = true;
          }
          else /* Any other error. */
          {
              IotLogError( "Failed to retrive the HTTPS body for response %d. Error code: %d", pCurrentHttpsResponse, status );
          }
  
          HTTPS_GOTO_CLEANUP();
      }
  
      IOT_FUNCTION_CLEANUP_BEGIN();
  
      /* Report errors back to the application. */
      if( HTTPS_FAILED( status ) )
      {
          if( pCurrentHttpsResponse->isAsync && pCurrentHttpsResponse->pCallbacks->errorCallback )
          {
              pCurrentHttpsResponse->pCallbacks->errorCallback( pCurrentHttpsResponse->pUserPrivData, NULL, pCurrentHttpsResponse, status );
          }
  
          pCurrentHttpsResponse->syncStatus = status;
      }
  
      /* If this is not a persistent request, the server would have closed it after sending a response, but we
       * disconnect anyways. If we are disconnecting there is is no point in wasting time
       * flushing the network. If the network is being disconnected we also do not schedule any pending requests. */
      if( fatalDisconnect || pCurrentHttpsResponse->isNonPersistent )
      {
          IotLogDebug( "Disconnecting response %d.", pCurrentHttpsResponse );
          disconnectStatus = IotHttpsClient_Disconnect( pHttpsConnection );
  
          if( ( pCurrentHttpsResponse != NULL ) && pCurrentHttpsResponse->isAsync && pCurrentHttpsResponse->pCallbacks->connectionClosedCallback )
          {
              pCurrentHttpsResponse->pCallbacks->connectionClosedCallback( pCurrentHttpsResponse->pUserPrivData, pHttpsConnection, disconnectStatus );
          }
  
          if( HTTPS_FAILED( disconnectStatus ) )
          {
              IotLogWarn( "Failed to disconnect response %d. Error code: %d.", pCurrentHttpsResponse, disconnectStatus );
          }
  
          /* If we disconnect, we do not process anymore requests. */
      }
      else
      {
          /* Set the processing state of the buffer to finished for completeness. This is also to prevent the parsing of the flush
           * data from incrementing any pointer in the HTTP response context. */
          pCurrentHttpsResponse->bufferProcessingState = PROCESSING_STATE_FINISHED;
  
          /* Flush the socket of the rest of the data if there is data left from this response. We need to do this
           * so that for the next request on this connection, there is not left over response from this request in
           * the next response buffer.
           *
           * If a continuous stream of data is coming in from the connection, with an unknown end, we may not be able to
           * flush the network data. It may sit here forever. A continuous stream should be ingested with the async workflow.
           *
           * All network errors are ignore here because network read will have read the data from network buffer despite
           * errors. */
          flushStatus = _flushHttpsNetworkData( pHttpsConnection, pCurrentHttpsResponse );
  
          if( flushStatus == IOT_HTTPS_PARSING_ERROR )
          {
              IotLogWarn( "There an error parsing the network flush data. The network buffer might not be fully flushed." );
          }
          else if( flushStatus != IOT_HTTPS_OK )
          {
              IotLogDebug( "Network error when flushing the https network data: %d", flushStatus );
          }
  
          IotMutex_Lock( &( pHttpsConnection->connectionMutex ) );
          /* Get the next request to process. */
          pQItem = IotDeQueue_PeekHead( &( pHttpsConnection->reqQ ) );
          IotMutex_Unlock( &( pHttpsConnection->connectionMutex ) );
  
          /* If there is a next request to process, then create a taskpool job to send the request. */
          if( pQItem != NULL )
          {
              /* Set this next request to send. */
              pNextHttpsRequest = IotLink_Container( _httpsRequest_t, pQItem, link );
  
              if( pNextHttpsRequest->scheduled == false )
              {
                  IotLogDebug( "Request %d is next in the queue. Now scheduling a task to send the request.", pNextHttpsRequest );
                  scheduleStatus = _scheduleHttpsRequestSend( pNextHttpsRequest );
  
                  /* If there was an error with scheduling the new task, then report it. */
                  if( HTTPS_FAILED( scheduleStatus ) )
                  {
                      IotLogError( "Error scheduling HTTPS request %d. Error code: %d", pNextHttpsRequest, scheduleStatus );
  
                      if( pNextHttpsRequest->isAsync && pNextHttpsRequest->pCallbacks->errorCallback )
                      {
                          pNextHttpsRequest->pCallbacks->errorCallback( pNextHttpsRequest->pUserPrivData, pNextHttpsRequest, NULL, scheduleStatus );
                      }
                      else
                      {
                          pNextHttpsRequest->pHttpsResponse->syncStatus = scheduleStatus;
                      }
                  }
              }
          }
          else
          {
              IotLogDebug( "Network receive callback found the request queue empty. A network send task was not scheduled." );
          }
      }
  
      /* Dequeue response from the response queue now that it is finished. */
      IotMutex_Lock( &( pHttpsConnection->connectionMutex ) );
  
      /* There could be a scenario where the request fails to send and the network server still responds,
       * In this case, the failed response will have been cancelled and removed from the queue. If the network
       * server still got a response, then the safest way to remove the current response is to remove it explicitly
       * from the queue instead of dequeuing the header of the queue which might not be the current response. */
      if( IotLink_IsLinked( &( pCurrentHttpsResponse->link ) ) )
      {
          IotDeQueue_Remove( &( pCurrentHttpsResponse->link ) );
      }
  
      IotMutex_Unlock( &( pHttpsConnection->connectionMutex ) );
  
      /* The first if-case below notifies IotHttpsClient_SendSync() that the response is finished receiving. When
       * IotHttpsClient_SendSync() returns the user is allowed to modify the user buffer used for the response context.
       * In the asynchronous case, the responseCompleteCallback notifies the application that the user buffer used for the
       * response context can be modified. Posting to the respFinishedSem or calling the responseCompleteCallback MUST be
       * mutually exclusive by wrapping in an if/else. If these were separate if-cases, then there could be a context
       * switch in between where the application modifies the buffer causing the next if-case to be executed. */
      if( pCurrentHttpsResponse->isAsync == false )
      {
          IotSemaphore_Post( &( pCurrentHttpsResponse->respFinishedSem ) );
      }
      else if( pCurrentHttpsResponse->pCallbacks->responseCompleteCallback )
      {
          /* Signal to a synchronous reponse that the response is complete. */
          pCurrentHttpsResponse->pCallbacks->responseCompleteCallback( pCurrentHttpsResponse->pUserPrivData, pCurrentHttpsResponse, status, pCurrentHttpsResponse->status );
      }
  }
  
  /*-----------------------------------------------------------*/
  
  static IotHttpsReturnCode_t _createHttpsConnection( IotHttpsConnectionHandle_t * pConnHandle,
                                                      IotHttpsConnectionInfo_t * pConnInfo )
  {
      HTTPS_FUNCTION_ENTRY( IOT_HTTPS_OK );
  
      IotNetworkError_t networkStatus = IOT_NETWORK_SUCCESS;
  
      /* The maximum string length of the ALPN protocols is configured in IOT_HTTPS_MAX_ALPN_PROTOCOLS_LENGTH.
       * The +1 is for the NULL terminator needed by IotNetworkCredentials_t.pAlpnProtos. */
      char pAlpnProtos[ IOT_HTTPS_MAX_ALPN_PROTOCOLS_LENGTH + 1 ] = { 0 };
  
      /* The maximum string length of the Server host name is configured in IOT_HTTPS_MAX_HOST_NAME_LENGTH.
       * This +1 is for the NULL terminator needed by IotNetworkServerInfo_t.pHostName. */
      char pHostName[ IOT_HTTPS_MAX_HOST_NAME_LENGTH + 1 ] = { 0 };
      bool connectionMutexCreated = false;
      IotNetworkServerInfo_t networkServerInfo = { 0 };
      IotNetworkCredentials_t networkCredentials = { 0 };
      _httpsConnection_t * pHttpsConnection = NULL;
      IotNetworkCredentials_t * pNetworkCredentials = NULL;
  
      HTTPS_ON_NULL_ARG_GOTO_CLEANUP( pConnInfo->userBuffer.pBuffer );
      HTTPS_ON_NULL_ARG_GOTO_CLEANUP( pConnInfo->pNetworkInterface );
      HTTPS_ON_NULL_ARG_GOTO_CLEANUP( pConnInfo->pAddress );
      HTTPS_ON_ARG_ERROR_GOTO_CLEANUP( pConnInfo->addressLen > 0 );
  
      /* Make sure the connection context can fit in the user buffer. */
      HTTPS_ON_ARG_ERROR_MSG_GOTO_CLEANUP( pConnInfo->userBuffer.bufferLen >= connectionUserBufferMinimumSize,
                                           IOT_HTTPS_INSUFFICIENT_MEMORY,
                                           "Buffer size is too small to initialize the connection context. User buffer size: %d, required minimum size; %d.",
                                           ( *pConnInfo ).userBuffer.bufferLen,
                                           connectionUserBufferMinimumSize );
  
      /* Make sure that the server address does not exceed the maximum permitted length. */
      HTTPS_ON_ARG_ERROR_MSG_GOTO_CLEANUP( pConnInfo->addressLen <= IOT_HTTPS_MAX_HOST_NAME_LENGTH,
                                           IOT_HTTPS_INVALID_PARAMETER,
                                           "IotHttpsConnectionInfo_t.addressLen has a host name length %d that exceeds maximum length %d.",
                                           pConnInfo->addressLen,
                                           IOT_HTTPS_MAX_HOST_NAME_LENGTH );
  
      /* Make sure that the ALPN protocols does not exceed the maximum permitted length. */
      HTTPS_ON_ARG_ERROR_MSG_GOTO_CLEANUP( pConnInfo->alpnProtocolsLen <= IOT_HTTPS_MAX_ALPN_PROTOCOLS_LENGTH,
                                           IOT_HTTPS_INVALID_PARAMETER,
                                           "IotHttpsConnectionInfo_t.alpnProtocolsLen of %d exceeds the configured maximum protocol length %d. See IOT_HTTPS_MAX_ALPN_PROTOCOLS_LENGTH for more information.",
                                           pConnInfo->alpnProtocolsLen,
                                           IOT_HTTPS_MAX_ALPN_PROTOCOLS_LENGTH );
  
      pHttpsConnection = ( _httpsConnection_t * ) ( pConnInfo->userBuffer.pBuffer );
  
      /* Start with the disconnected state. */
      pHttpsConnection->isConnected = false;
  
      /* Initialize disconnection state keeper. */
      pHttpsConnection->isDestroyed = false;
  
      /* Initialize the queue of responses and requests. */
      IotDeQueue_Create( &( pHttpsConnection->reqQ ) );
      IotDeQueue_Create( &( pHttpsConnection->respQ ) );
  
      /* This timeout is used to wait for a response on the connection as well as
       * for the timeout for the connect operation. */
      if( pConnInfo->timeout == 0 )
      {
          pHttpsConnection->timeout = IOT_HTTPS_RESPONSE_WAIT_MS;
      }
      else
      {
          pHttpsConnection->timeout = pConnInfo->timeout;
      }
  
      /* pNetworkInterface contains all the routines to be able to send/receive data on the network. */
      pHttpsConnection->pNetworkInterface = pConnInfo->pNetworkInterface;
  
      /* The address from the connection configuration information is copied to a local buffer because a NULL pointer
       * is required in IotNetworkServerInfo_t.pHostName. IotNetworkServerInfo_t contains the server information needed
       * by the network interface to create the connection. */
      memcpy( pHostName, pConnInfo->pAddress, pConnInfo->addressLen );
      pHostName[ pConnInfo->addressLen ] = '\0';
      /* Set it in the IOT network abstractions server information parameter. */
      networkServerInfo.pHostName = pHostName;
      networkServerInfo.port = pConnInfo->port;
  
      /* If this is TLS connection, then set the network credentials. */
      if( ( pConnInfo->flags & IOT_HTTPS_IS_NON_TLS_FLAG ) == 0 )
      {
          if( pConnInfo->flags & IOT_HTTPS_DISABLE_SNI )
          {
              networkCredentials.disableSni = true;
          }
          else
          {
              networkCredentials.disableSni = false;
          }
  
          if( pConnInfo->pAlpnProtocols != NULL )
          {
              /* The alpn protocol strings in IotNetworkCredentials_t require a NULL terminator, so the alpn protocol
               * string in the connection configuration information is copied to a local buffer to append the NULL
               * terminator. */
              memcpy( pAlpnProtos, pConnInfo->pAlpnProtocols, pConnInfo->alpnProtocolsLen );
              pAlpnProtos[ pConnInfo->alpnProtocolsLen ] = '\0';
              networkCredentials.pAlpnProtos = pAlpnProtos;
          }
          else
          {
              networkCredentials.pAlpnProtos = NULL;
          }
  
          /* If any of these are NULL a network error will result when trying to make the connection. Because there is
           * no invalid memory access resulting from these configurations being NULL, it is not check at the start
           * of the function. */
          networkCredentials.pRootCa = pConnInfo->pCaCert;
          networkCredentials.rootCaSize = pConnInfo->caCertLen;
          networkCredentials.pClientCert = pConnInfo->pClientCert;
          networkCredentials.clientCertSize = pConnInfo->clientCertLen;
          networkCredentials.pPrivateKey = pConnInfo->pPrivateKey;
          networkCredentials.privateKeySize = pConnInfo->privateKeyLen;
  
          pNetworkCredentials = &networkCredentials;
      }
      else
      {
          /* create() takes a NULL if there is no TLS configuration. */
          pNetworkCredentials = NULL;
      }
  
      /* create() will connect to the server specified in addition to creating other network layer
       *  specific resources. */
      networkStatus = pHttpsConnection->pNetworkInterface->create( &networkServerInfo,
                                                                   pNetworkCredentials,
                                                                   &( pHttpsConnection->pNetworkConnection ) );
  
      /* Check to see if the network connection succeeded. If it did not succeed,
       * then the output parameter pConnHandle will be used to return NULL and the
       * function returns an error. */
      if( networkStatus != IOT_NETWORK_SUCCESS )
      {
          IotLogError( "Failed to connect to the server at %.*s on port %d with error: %d",
                       pConnInfo->addressLen,
                       pConnInfo->pAddress,
                       pConnInfo->port,
                       networkStatus );
          HTTPS_SET_AND_GOTO_CLEANUP( IOT_HTTPS_CONNECTION_ERROR );
      }
  
      /* The connection succeeded so set the state to connected. */
      pHttpsConnection->isConnected = true;
  
      /* The receive callback is invoked by the network layer when data is ready
       * to be read from the network. */
      networkStatus = pHttpsConnection->pNetworkInterface->setReceiveCallback( pHttpsConnection->pNetworkConnection,
                                                                               _networkReceiveCallback,
                                                                               pHttpsConnection );
  
      if( networkStatus != IOT_NETWORK_SUCCESS )
      {
          IotLogError( "Failed to connect to set the HTTPS receive callback. " );
          HTTPS_SET_AND_GOTO_CLEANUP( IOT_HTTPS_INTERNAL_ERROR );
      }
  
      /* Connection was successful, so create synchronization primitives. */
  
      connectionMutexCreated = IotMutex_Create( &( pHttpsConnection->connectionMutex ), false );
  
      if( !connectionMutexCreated )
      {
          IotLogError( "Failed to create an internal mutex." );
          HTTPS_SET_AND_GOTO_CLEANUP( IOT_HTTPS_INTERNAL_ERROR );
      }
  
      /* Return the new connection information. */
      *pConnHandle = pHttpsConnection;
  
      HTTPS_FUNCTION_CLEANUP_BEGIN();
  
      /* If we failed anywhere in the connection process, then destroy the semaphores created. */
      if( HTTPS_FAILED( status ) )
      {
          /* If there was a connect was successful, disconnect from the network.  */
          if( ( pHttpsConnection != NULL ) && ( pHttpsConnection->isConnected ) )
          {
              _networkDisconnect( pHttpsConnection );
              _networkDestroy( pHttpsConnection );
          }
  
          if( connectionMutexCreated )
          {
              IotMutex_Destroy( &( pHttpsConnection->connectionMutex ) );
          }
  
          /* Set the connection handle as NULL if everything failed. */
          *pConnHandle = NULL;
      }
  
      HTTPS_FUNCTION_CLEANUP_END();
  }
  
  /*-----------------------------------------------------------*/
  
  static void _networkDisconnect( _httpsConnection_t * pHttpsConnection )
  {
      IotNetworkError_t networkStatus = IOT_NETWORK_SUCCESS;
  
      networkStatus = pHttpsConnection->pNetworkInterface->close( pHttpsConnection->pNetworkConnection );
  
      if( networkStatus != IOT_NETWORK_SUCCESS )
      {
          IotLogWarn( "Failed to shutdown the socket with error code: %d", networkStatus );
      }
  }
  
  /*-----------------------------------------------------------*/
  
  static void _networkDestroy( _httpsConnection_t * pHttpsConnection )
  {
      IotNetworkError_t networkStatus = IOT_NETWORK_SUCCESS;
  
      networkStatus = pHttpsConnection->pNetworkInterface->destroy( pHttpsConnection->pNetworkConnection );
  
      if( networkStatus != IOT_NETWORK_SUCCESS )
      {
          IotLogWarn( "Failed to shutdown the socket with error code: %d", networkStatus );
      }
  }
  
  /*-----------------------------------------------------------*/
  
  static IotHttpsReturnCode_t _addHeader( _httpsRequest_t * pHttpsRequest,
                                          const char * pName,
                                          uint32_t nameLen,
                                          const char * pValue,
                                          uint32_t valueLen )
  {
      HTTPS_FUNCTION_ENTRY( IOT_HTTPS_OK );
  
      int headerFieldSeparatorLen = HTTPS_HEADER_FIELD_SEPARATOR_LENGTH;
      uint32_t additionalLength = nameLen + headerFieldSeparatorLen + valueLen + HTTPS_END_OF_HEADER_LINES_INDICATOR_LENGTH;
      uint32_t possibleLastHeaderAdditionalLength = HTTPS_END_OF_HEADER_LINES_INDICATOR_LENGTH;
  
      /* Check if there is enough space to add the header field and value
       * (name:value\r\n). We need to add a "\r\n" at the end of headers. The use of
       * possibleLastHeaderAdditionalLength is to make sure that there is always
       * space for the last "\r\n". */
      if( ( additionalLength + possibleLastHeaderAdditionalLength ) > ( pHttpsRequest->pHeadersEnd - pHttpsRequest->pHeadersCur ) )
      {
          IotLogError( "There is %d space left in the header buffer, but we want to add %d more of header.",
                       pHttpsRequest->pHeadersEnd - pHttpsRequest->pHeadersCur,
                       additionalLength + possibleLastHeaderAdditionalLength );
          HTTPS_SET_AND_GOTO_CLEANUP( IOT_HTTPS_INSUFFICIENT_MEMORY );
      }
  
      memcpy( pHttpsRequest->pHeadersCur, pName, nameLen );
      pHttpsRequest->pHeadersCur += nameLen;
      memcpy( pHttpsRequest->pHeadersCur, HTTPS_HEADER_FIELD_SEPARATOR, headerFieldSeparatorLen );
      pHttpsRequest->pHeadersCur += headerFieldSeparatorLen;
      memcpy( pHttpsRequest->pHeadersCur, pValue, valueLen );
      pHttpsRequest->pHeadersCur += valueLen;
      memcpy( pHttpsRequest->pHeadersCur, HTTPS_END_OF_HEADER_LINES_INDICATOR, HTTPS_END_OF_HEADER_LINES_INDICATOR_LENGTH );
      pHttpsRequest->pHeadersCur += HTTPS_END_OF_HEADER_LINES_INDICATOR_LENGTH;
      IotLogDebug( "Wrote header: \"%s: %.*s\r\n\". Space left in request user buffer: %d",
                   pName,
                   valueLen,
                   pValue,
                   pHttpsRequest->pHeadersEnd - pHttpsRequest->pHeadersCur );
  
      HTTPS_FUNCTION_EXIT_NO_CLEANUP();
  }
  
  /*-----------------------------------------------------------*/
  
  static IotHttpsReturnCode_t _networkSend( _httpsConnection_t * pHttpsConnection,
                                            uint8_t * pBuf,
                                            size_t len )
  {
      HTTPS_FUNCTION_ENTRY( IOT_HTTPS_OK );
  
      size_t numBytesSent = 0;
      size_t numBytesSentTotal = 0;
      size_t sendLength = len;
  
      while( numBytesSentTotal < sendLength )
      {
          numBytesSent = pHttpsConnection->pNetworkInterface->send( pHttpsConnection->pNetworkConnection,
                                                                    &( pBuf[ numBytesSentTotal ] ),
                                                                    sendLength - numBytesSentTotal );
  
          /* pNetworkInterface->send returns 0 on error. */
          if( numBytesSent == 0 )
          {
              IotLogError( "Error in sending the HTTPS headers. Error code: %d", numBytesSent );
              break;
          }
  
          numBytesSentTotal += numBytesSent;
      }
  
      if( numBytesSentTotal != sendLength )
      {
          IotLogError( "Error sending data on the network. We sent %d but there were total %d.", numBytesSentTotal, sendLength );
          HTTPS_SET_AND_GOTO_CLEANUP( IOT_HTTPS_NETWORK_ERROR );
      }
  
      HTTPS_FUNCTION_EXIT_NO_CLEANUP();
  }
  
  /*-----------------------------------------------------------*/
  
  static IotHttpsReturnCode_t _networkRecv( _httpsConnection_t * pHttpsConnection,
                                            uint8_t * pBuf,
                                            size_t bufLen,
                                            size_t * numBytesRecv )
  {
      HTTPS_FUNCTION_ENTRY( IOT_HTTPS_OK );
  
      /* The HTTP server could send the header and the body in two separate TCP packets. If that is the case, then
       * receiveUpTo will return return the full headers first. Then on a second call, the body will be returned.
       * If the http parser receives just the headers despite the content length being greater than  */
      *numBytesRecv = pHttpsConnection->pNetworkInterface->receiveUpto( pHttpsConnection->pNetworkConnection,
                                                                        pBuf,
                                                                        bufLen );
  
      IotLogDebug( "The network interface receive returned %d.", numBytesRecv );
  
      /* We return IOT_HTTPS_NETWORK_ERROR only if we receive nothing. Receiving less
       * data than requested is okay because it is not known in advance how much data
       * we are going to receive and therefore we request for the available buffer
       * size. */
      if( *numBytesRecv == 0 )
      {
          IotLogError( "Error in receiving the HTTPS response message. Socket Error code %d", *numBytesRecv );
          HTTPS_SET_AND_GOTO_CLEANUP( IOT_HTTPS_NETWORK_ERROR );
  
          /* A network error is returned when zero is received because that would indicate that either there
          * was a network error or there was a timeout reading data. If there was timeout reading data, then
          * the server was too slow to respond. If the server is too slow to respond, then a network error must
          * be returned to trigger a connection close. The connection must close after the network error so
          * that the response from this request does not piggyback on the response from the next request. */
      }
  
      HTTPS_FUNCTION_EXIT_NO_CLEANUP();
  }
  
  /*-----------------------------------------------------------*/
  
  static IotHttpsReturnCode_t _sendHttpsHeaders( _httpsConnection_t * pHttpsConnection,
                                                 uint8_t * pHeadersBuf,
                                                 uint32_t headersLength,
                                                 bool isNonPersistent,
                                                 uint32_t contentLength )
  {
      HTTPS_FUNCTION_ENTRY( IOT_HTTPS_OK );
  
      const char * connectionHeader = NULL;
      int numWritten = 0;
      int connectionHeaderLen = 0;
      /* The Content-Length header of the form "Content-Length: N\r\n" with a NULL terminator for snprintf. */
      char contentLengthHeaderStr[ HTTPS_MAX_CONTENT_LENGTH_LINE_LENGTH + 1 ];
  
      /* The HTTP headers to send after the headers in pHeadersBuf are the Content-Length and the Connection type and
       * the final "\r\n" to indicate the end of the the header lines. Note that we are using
       * HTTPS_CONNECTION_KEEP_ALIVE_HEADER_LINE_LENGTH because length of "Connection: keep-alive\r\n" is
       * more than "Connection: close\r\n". Creating a buffer of bigger size ensures that
       * both the connection type strings will fit in the buffer. */
      char finalHeaders[ HTTPS_MAX_CONTENT_LENGTH_LINE_LENGTH + HTTPS_CONNECTION_KEEP_ALIVE_HEADER_LINE_LENGTH + HTTPS_END_OF_HEADER_LINES_INDICATOR_LENGTH ] = { 0 };
  
      /* Send the headers passed into this function first. These headers are not termined with a second set of "\r\n". */
      status = _networkSend( pHttpsConnection, pHeadersBuf, headersLength );
  
      if( HTTPS_FAILED( status ) )
      {
          IotLogError( "Error sending the HTTPS headers in the request user buffer. Error code: %d", status );
          HTTPS_GOTO_CLEANUP();
      }
  
      /* If there is a Content-Length, then write that to the finalHeaders to send. */
      if( contentLength > 0 )
      {
          numWritten = snprintf( contentLengthHeaderStr,
                                 sizeof( contentLengthHeaderStr ),
                                 "%s: %u\r\n",
                                 HTTPS_CONTENT_LENGTH_HEADER,
                                 ( unsigned int ) contentLength );
      }
  
      if( ( numWritten < 0 ) || ( numWritten >= sizeof( contentLengthHeaderStr ) ) )
      {
          IotLogError( "Internal error in snprintf() in _sendHttpsHeaders(). Error code %d.", numWritten );
          HTTPS_SET_AND_GOTO_CLEANUP( IOT_HTTPS_INTERNAL_ERROR );
      }
  
      /* snprintf() succeeded so copy that to the finalHeaders. */
      memcpy( finalHeaders, contentLengthHeaderStr, numWritten );
  
      /* Write the connection persistence type to the final headers. */
      if( isNonPersistent )
      {
          connectionHeader = HTTPS_CONNECTION_CLOSE_HEADER_LINE;
          connectionHeaderLen = FAST_MACRO_STRLEN( HTTPS_CONNECTION_CLOSE_HEADER_LINE );
      }
      else
      {
          connectionHeader = HTTPS_CONNECTION_KEEP_ALIVE_HEADER_LINE;
          connectionHeaderLen = FAST_MACRO_STRLEN( HTTPS_CONNECTION_KEEP_ALIVE_HEADER_LINE );
      }
  
      memcpy( &finalHeaders[ numWritten ], connectionHeader, connectionHeaderLen );
      numWritten += connectionHeaderLen;
      memcpy( &finalHeaders[ numWritten ], HTTPS_END_OF_HEADER_LINES_INDICATOR, HTTPS_END_OF_HEADER_LINES_INDICATOR_LENGTH );
      numWritten += HTTPS_END_OF_HEADER_LINES_INDICATOR_LENGTH;
  
      status = _networkSend( pHttpsConnection, ( uint8_t * ) finalHeaders, numWritten );
  
      if( HTTPS_FAILED( status ) )
      {
          IotLogError( "Error sending final HTTPS Headers \r\n%s. Error code: %d", finalHeaders, status );
          HTTPS_GOTO_CLEANUP();
      }
  
      HTTPS_FUNCTION_EXIT_NO_CLEANUP();
  }
  
  /*-----------------------------------------------------------*/
  
  static IotHttpsReturnCode_t _sendHttpsBody( _httpsConnection_t * pHttpsConnection,
                                              uint8_t * pBodyBuf,
                                              uint32_t bodyLength )
  {
      HTTPS_FUNCTION_ENTRY( IOT_HTTPS_OK );
  
      status = _networkSend( pHttpsConnection, pBodyBuf, bodyLength );
  
      if( HTTPS_FAILED( status ) )
      {
          IotLogError( "Error sending final HTTPS body at location 0x%x. Error code: %d", pBodyBuf, status );
          HTTPS_GOTO_CLEANUP();
      }
  
      HTTPS_FUNCTION_EXIT_NO_CLEANUP();
  }
  
  /*-----------------------------------------------------------*/
  
  static IotHttpsReturnCode_t _parseHttpsMessage( _httpParserInfo_t * pHttpParserInfo,
                                                  char * pBuf,
                                                  size_t len )
  {
      HTTPS_FUNCTION_ENTRY( IOT_HTTPS_OK );
  
      size_t parsedBytes = 0;
      const char * pHttpParserErrorDescription = NULL;
      http_parser * pHttpParser = &( pHttpParserInfo->responseParser );
  
      IotLogDebug( "Now parsing HTTP message buffer to process a response." );
      parsedBytes = pHttpParserInfo->parseFunc( pHttpParser, &_httpParserSettings, pBuf, len );
      IotLogDebug( "http-parser parsed %d bytes out of %d specified.", parsedBytes, len );
  
      /* If the parser fails with HPE_CLOSED_CONNECTION or HPE_INVALID_CONSTANT that simply means there
       * was data beyond the end of the message. We do not fail in this case because we give the whole
       * header buffer or body buffer to the parser even if it is only partly filled with data.
       * Errors <= HPE_CB_chunk_complete means that a non-zero number was returned from some callback.
       * A nonzero number is returned from some callbacks when we want to stop the parser early
       * for example - a HEAD request or the user explicitly asked to ignore the body by not
       * providing the body buffer. */
      if( ( pHttpParser->http_errno != 0 ) &&
          ( HTTP_PARSER_ERRNO( pHttpParser ) != HPE_CLOSED_CONNECTION ) &&
          ( HTTP_PARSER_ERRNO( pHttpParser ) != HPE_INVALID_CONSTANT ) &&
          ( HTTP_PARSER_ERRNO( pHttpParser ) > HPE_CB_chunk_complete ) )
      {
          pHttpParserErrorDescription = http_errno_description( HTTP_PARSER_ERRNO( pHttpParser ) );
          IotLogError( "http_parser failed on the http response with error: %s", pHttpParserErrorDescription );
          HTTPS_SET_AND_GOTO_CLEANUP( IOT_HTTPS_PARSING_ERROR );
      }
  
      HTTPS_FUNCTION_EXIT_NO_CLEANUP();
  }
  
  /*-----------------------------------------------------------*/
  
  static void _incrementNextLocationToWriteBeyondParsed( uint8_t ** pBufCur,
                                                         uint8_t ** pBufEnd )
  {
      /* There is an edge case where the final one or two character received in the header buffer is part of
       * the header field separator ": " or part of the header line end "\r\n" delimitters. When this
       * happens, pHeadersCur in the response will point not the end of the buffer, but to a character in
       * the delimiter. For example:
       * Let's say this is our current header buffer after receiving and parsing:
       * ["HTTP/1.1 200 OK\r\n\header0: value0\r\nheader1: value1\r\n"]
       * pHeadersCur will point to \r because the http-parser does not invoke a callback on the
       * delimitters. Since no callback is invoked, pHeadersCur is not incremented. pHeadersEnd points to
       * the end of the header buffer which is the unwritable memory location right after the final '\n'.
       * Because pHeadersCur is less than pHeaderEnd we loop again and receive on the network causing the
       * buffer to look like this:
       * ["HTTP/1.1 200 OK\r\n\header0: value0\r\nheader1: value1he"]
       * Which will cause an incorrect header1 value to be read if the application decides to read it with
       * IotHttpsClient_ReadHeader().
       *
       * If our header buffer looks like:
       * ["HTTP/1.1 200 OK\r\n\header0: value0\r\nheader1: "]
       * then pHeaderCur will point to the colon.
       *
       * If our header buffer looks like:
       * ["HTTP/1.1 200 OK\r\n\header0: value0\r\nheader1:"]
       * then pHeaderCur will point to the colon.
       *
       * If our header buffer looks like
       * ["HTTP/1.1 200 OK\r\n\header0: value0\r\nheader1: value1 "]
       * then http-parser will consider that space as part of value1.
       *
       * If our header buffer looks like
       * ["HTTP/1.1 200 OK\r\n\header0: value0\r\nheader1: value1\r"]
       * then pHeaderCur will point to the carriage return.
       *
       * If our header buffer looks like
       * ["HTTP/1.1 200 OK\r\n\header0: value0\r\nheader1: value1\r\n"]
       * As explained in the example above, pHeaderCur will point to the carriage return.
       *
       * If we somehow receive a partial HTTP response message in our zeroed-out header buffer:
       * case 1: ["HTTP/1.1 200 OK\r\nheader0: value0\r\nheader1: value1\r\0\0\0\0\0\0\0"]
       * case 2: ["HTTP/1.1 200 OK\r\nheader0: value0\r\nheader1: value1\r\n\0\0\0\0\0\0"]
       * case 3: ["HTTP/1.1 200 OK\r\nheader0: value0\r\nheader1:\0\0\0\0\0\0\0\0\0\0\0"]
       * case 4: ["HTTP/1.1 200 OK\r\nheader0: value0\r\nheader1: \0\0\0\0\0\0\0\0\0\0\0"]
       * then parser may fail or append all of the NULL characters to a header field name or value. */
      while( *pBufCur < *pBufEnd )
      {
          if( **pBufCur == CARRIAGE_RETURN_CHARACTER )
          {
              ( *pBufCur )++;
          }
          else if( **pBufCur == NEWLINE_CHARACTER )
          {
              ( *pBufCur )++;
              break;
          }
          else if( **pBufCur == COLON_CHARACTER )
          {
              ( *pBufCur )++;
          }
          else if( ( **pBufCur == SPACE_CHARACTER ) && ( *( *pBufCur - 1 ) == COLON_CHARACTER ) )
          {
              ( *pBufCur )++;
              break;
          }
          else
          {
              break;
          }
      }
  }
  
  /*-----------------------------------------------------------*/
  
  static IotHttpsReturnCode_t _receiveHttpsMessage( _httpsConnection_t * pHttpsConnection,
                                                    _httpParserInfo_t * pHttpParserInfo,
                                                    IotHttpsResponseParserState_t * pCurrentParserState,
                                                    IotHttpsResponseParserState_t finalParserState,
                                                    IotHttpsResponseBufferState_t currentBufferProcessingState,
                                                    uint8_t ** pBufCur,
                                                    uint8_t ** pBufEnd )
  {
      HTTPS_FUNCTION_ENTRY( IOT_HTTPS_OK );
  
      size_t numBytesRecv = 0;
  
      /* The final parser state is either the end of the header lines or the end of the entity body. This state is set in
       * the http-parser callbacks. */
      while( ( *pCurrentParserState < finalParserState ) && ( *pBufEnd - *pBufCur > 0 ) )
      {
          status = _networkRecv( pHttpsConnection,
                                 *pBufCur,
                                 *pBufEnd - *pBufCur,
                                 &numBytesRecv );
  
          /* A network error in _networkRecv is returned only when we received zero bytes. In that case, there is
           * no point in parsing we return immediately with the network error. */
          if( HTTPS_FAILED( status ) )
          {
              IotLogError( "Network error receiving the HTTPS response headers. Error code: %d", status );
              break;
          }
  
          status = _parseHttpsMessage( pHttpParserInfo, ( char * ) ( *pBufCur ), numBytesRecv );
  
          if( HTTPS_FAILED( status ) )
          {
              IotLogError( "Failed to parse the message buffer with error: %d", pHttpParserInfo->responseParser.http_errno );
              break;
          }
  
          /* If the current buffer being filled is the header buffer, then \r\n header line separators should not get
           * overwritten on the next network read. See _incrementNextLocationToWriteBeyondParsed() for more
           * information. */
          if( currentBufferProcessingState == PROCESSING_STATE_FILLING_HEADER_BUFFER )
          {
              _incrementNextLocationToWriteBeyondParsed( pBufCur, pBufEnd );
          }
  
          /* The _httResponse->pHeadersCur pointer is updated in the http_parser callbacks. */
          IotLogDebug( "There is %d of space left in the buffer.", *pBufEnd - *pBufCur );
      }
  
      /* If we did not reach the end of the headers or body in the parser callbacks, then the buffer configured does not
       * fit all of that part of the HTTP message. */
      if( *pCurrentParserState < finalParserState )
      {
          IotLogDebug( "There are still more data on the network. It could not fit into the specified length %d.",
                       *pBufEnd - *pBufCur );
      }
  
      HTTPS_GOTO_CLEANUP();
      HTTPS_FUNCTION_EXIT_NO_CLEANUP();
  }
  
  /*-----------------------------------------------------------*/
  
  static IotHttpsReturnCode_t _receiveHttpsHeaders( _httpsConnection_t * pHttpsConnection,
                                                    _httpsResponse_t * pHttpsResponse )
  {
      HTTPS_FUNCTION_ENTRY( IOT_HTTPS_OK );
  
      pHttpsResponse->bufferProcessingState = PROCESSING_STATE_FILLING_HEADER_BUFFER;
  
      IotLogDebug( "Now attempting to receive the HTTP response headers into a buffer with length %d.",
                   pHttpsResponse->pHeadersEnd - pHttpsResponse->pHeadersCur );
  
      status = _receiveHttpsMessage( pHttpsConnection,
                                     &( pHttpsResponse->httpParserInfo ),
                                     &( pHttpsResponse->parserState ),
                                     PARSER_STATE_HEADERS_COMPLETE,
                                     PROCESSING_STATE_FILLING_HEADER_BUFFER,
                                     &( pHttpsResponse->pHeadersCur ),
                                     &( pHttpsResponse->pHeadersEnd ) );
  
      if( HTTPS_FAILED( status ) )
      {
          IotLogError( "Error receiving the HTTP headers. Error code %d", status );
          HTTPS_GOTO_CLEANUP();
      }
  
      HTTPS_FUNCTION_EXIT_NO_CLEANUP();
  }
  
  /*-----------------------------------------------------------*/
  
  /* _receiveHttpsHeaders() must be called first before this function is called. */
  static IotHttpsReturnCode_t _receiveHttpsBody( _httpsConnection_t * pHttpsConnection,
                                                 _httpsResponse_t * pHttpsResponse )
  {
      HTTPS_FUNCTION_ENTRY( IOT_HTTPS_OK );
  
      IotLogDebug( "Now attempting to receive the HTTP response body into a buffer with length %d.",
                   pHttpsResponse->pBodyEnd - pHttpsResponse->pBodyCur );
  
      pHttpsResponse->bufferProcessingState = PROCESSING_STATE_FILLING_BODY_BUFFER;
  
      status = _receiveHttpsMessage( pHttpsConnection,
                                     &( pHttpsResponse->httpParserInfo ),
                                     &( pHttpsResponse->parserState ),
                                     PARSER_STATE_BODY_COMPLETE,
                                     PROCESSING_STATE_FILLING_BODY_BUFFER,
                                     &( pHttpsResponse->pBodyCur ),
                                     &( pHttpsResponse->pBodyEnd ) );
  
      if( HTTPS_FAILED( status ) )
      {
          IotLogError( "Error receiving the HTTP body. Error code %d", status );
          HTTPS_GOTO_CLEANUP();
      }
  
      HTTPS_FUNCTION_CLEANUP_BEGIN();
  
      IotLogDebug( "The remaining content length on the network is %d.",
                   pHttpsResponse->httpParserInfo.responseParser.content_length );
  
      HTTPS_FUNCTION_CLEANUP_END();
  }
  
  /*-----------------------------------------------------------*/
  
  static IotHttpsReturnCode_t _flushHttpsNetworkData( _httpsConnection_t * pHttpsConnection,
                                                      _httpsResponse_t * pHttpsResponse )
  {
      HTTPS_FUNCTION_ENTRY( IOT_HTTPS_OK );
  
      static uint8_t flushBuffer[ IOT_HTTPS_MAX_FLUSH_BUFFER_SIZE ] = { 0 };
      const char * pHttpParserErrorDescription = NULL;
      IotHttpsReturnCode_t parserStatus = IOT_HTTPS_OK;
      IotHttpsReturnCode_t networkStatus = IOT_HTTPS_OK;
      size_t numBytesRecv = 0;
  
      /* Even if there is not body, the parser state will become body complete after the headers finish. */
      while( pHttpsResponse->parserState < PARSER_STATE_BODY_COMPLETE )
      {
          IotLogDebug( "Now clearing the rest of the response data on the socket. " );
          networkStatus = _networkRecv( pHttpsConnection, flushBuffer, IOT_HTTPS_MAX_FLUSH_BUFFER_SIZE, &numBytesRecv );
  
          /* Run this through the parser so that we can get the end of the HTTP message, instead of simply timing out the socket to stop.
           * If we relied on the socket timeout to stop reading the network socket, then the server may close the connection. */
          parserStatus = _parseHttpsMessage( &( pHttpsResponse->httpParserInfo ), ( char * ) flushBuffer, numBytesRecv );
  
          if( HTTPS_FAILED( parserStatus ) )
          {
              pHttpParserErrorDescription = http_errno_description( HTTP_PARSER_ERRNO( &pHttpsResponse->httpParserInfo.responseParser ) );
              IotLogError( "Network Flush: Failed to parse the response body buffer with error: %d, %s",
                           pHttpsResponse->httpParserInfo.responseParser.http_errno,
                           pHttpParserErrorDescription );
              break;
          }
  
          /* If there is a network error then we want to stop clearing out the buffer. */
          if( HTTPS_FAILED( networkStatus ) )
          {
              IotLogWarn( "Network Flush: Error receiving the rest of the HTTP response. Error code: %d",
                          networkStatus );
              break;
          }
      }
  
      /* All network errors except timeouts are returned. */
      if( HTTPS_FAILED( networkStatus ) )
      {
          status = networkStatus;
      }
      else
      {
          status = parserStatus;
      }
  
      HTTPS_GOTO_CLEANUP();
  
      HTTPS_FUNCTION_EXIT_NO_CLEANUP();
  }
  
  /*-----------------------------------------------------------*/
  
  static IotHttpsReturnCode_t _sendHttpsHeadersAndBody( _httpsConnection_t * pHttpsConnection,
                                                        _httpsRequest_t * pHttpsRequest )
  {
      HTTPS_FUNCTION_ENTRY( IOT_HTTPS_OK );
  
      /* Send the HTTP headers. */
      status = _sendHttpsHeaders( pHttpsConnection,
                                  pHttpsRequest->pHeaders,
                                  pHttpsRequest->pHeadersCur - pHttpsRequest->pHeaders,
                                  pHttpsRequest->isNonPersistent,
                                  pHttpsRequest->bodyLength );
  
      if( HTTPS_FAILED( status ) )
      {
          IotLogError( "Error sending the HTTPS headers with error code: %d", status );
          HTTPS_GOTO_CLEANUP();
      }
  
      if( ( pHttpsRequest->pBody != NULL ) && ( pHttpsRequest->bodyLength > 0 ) )
      {
          status = _sendHttpsBody( pHttpsConnection, pHttpsRequest->pBody, pHttpsRequest->bodyLength );
  
          if( HTTPS_FAILED( status ) )
          {
              IotLogError( "Error sending final HTTPS body. Return code: %d", status );
              HTTPS_GOTO_CLEANUP();
          }
      }
  
      HTTPS_FUNCTION_EXIT_NO_CLEANUP();
  }
  
  /*-----------------------------------------------------------*/
  
  static void _sendHttpsRequest( IotTaskPool_t pTaskPool,
                                 IotTaskPoolJob_t pJob,
                                 void * pUserContext )
  {
      HTTPS_FUNCTION_ENTRY( IOT_HTTPS_OK );
  
      _httpsRequest_t * pHttpsRequest = ( _httpsRequest_t * ) ( pUserContext );
      _httpsConnection_t * pHttpsConnection = pHttpsRequest->pHttpsConnection;
      _httpsResponse_t * pHttpsResponse = pHttpsRequest->pHttpsResponse;
      IotHttpsReturnCode_t disconnectStatus = IOT_HTTPS_OK;
      IotHttpsReturnCode_t scheduleStatus = IOT_HTTPS_OK;
      IotLink_t * pQItem = NULL;
      _httpsRequest_t * pNextHttpsRequest = NULL;
  
      ( void ) pTaskPool;
      ( void ) pJob;
  
      IotLogDebug( "Task with request ID: %d started.", pHttpsRequest );
  
      if( pHttpsRequest->cancelled == true )
      {
          IotLogDebug( "Request ID: %d was cancelled.", pHttpsRequest );
          HTTPS_SET_AND_GOTO_CLEANUP( IOT_HTTPS_SEND_ABORT );
      }
  
      /* To protect against out of order network data from a rouge server, signal that the request is
       * not finished sending. */
      pHttpsResponse->reqFinishedSending = false;
  
      /* Queue the response to expect from the network. */
      IotMutex_Lock( &( pHttpsConnection->connectionMutex ) );
      IotDeQueue_EnqueueTail( &( pHttpsConnection->respQ ), &( pHttpsResponse->link ) );
      IotMutex_Unlock( &( pHttpsConnection->connectionMutex ) );
  
      /* Get the headers from the application. For a synchronous request the application should have appended extra
       * headers before this point. */
      if( pHttpsRequest->isAsync && pHttpsRequest->pCallbacks->appendHeaderCallback )
      {
          pHttpsRequest->pCallbacks->appendHeaderCallback( pHttpsRequest->pUserPrivData, pHttpsRequest );
      }
  
      if( pHttpsRequest->cancelled == true )
      {
          IotLogDebug( "Request ID: %d was cancelled.", pHttpsRequest );
          HTTPS_SET_AND_GOTO_CLEANUP( IOT_HTTPS_SEND_ABORT );
      }
  
      /* Ask the user for data to write body to the network. We only ask the user once. This is so that
       * we can calculate the Content-Length to send.*/
      if( pHttpsRequest->isAsync && pHttpsRequest->pCallbacks->writeCallback )
      {
          /* If there is data, then a Content-Length header value will be provided and we send the headers
           * before that user data. */
          pHttpsRequest->pCallbacks->writeCallback( pHttpsRequest->pUserPrivData, pHttpsRequest );
      }
  
      if( HTTPS_FAILED( pHttpsRequest->bodyTxStatus ) )
      {
          IotLogError( "Failed to send the headers and body over the network during the writeCallback. Error code: %d.",
                       status );
          HTTPS_SET_AND_GOTO_CLEANUP( pHttpsRequest->bodyTxStatus );
      }
  
      if( pHttpsRequest->cancelled == true )
      {
          IotLogDebug( "Request ID: %d was cancelled.", pHttpsRequest );
          HTTPS_SET_AND_GOTO_CLEANUP( IOT_HTTPS_SEND_ABORT );
      }
  
      /* If this is a synchronous request then the header and body were configured beforehand. The header and body
       * are sent now. For an asynchronous request, the header and body are sent in IotHttpsClient_WriteRequestBody()
       * which is to be invoked in #IotHttpsClientCallbacks_t.writeCallback(). If the application never invokes
       * IotHttpsClient_WriteRequestBody(), then pHttpsRequest->pBody will be NULL. In this case we still want to
       * send whatever headers we have.  */
      if( ( pHttpsRequest->isAsync == false ) ||
          ( ( pHttpsRequest->isAsync ) && ( pHttpsRequest->pBody == NULL ) ) )
      {
          status = _sendHttpsHeadersAndBody( pHttpsConnection, pHttpsRequest );
  
          if( HTTPS_FAILED( status ) )
          {
              IotLogError( "Failed to send the headers and body on the network. Error code: %d", status );
              HTTPS_GOTO_CLEANUP();
          }
      }
  
      HTTPS_FUNCTION_CLEANUP_BEGIN();
  
      /* The request has finished sending. This indicates to the network receive callback that the request was
       * finished, so a response received on the network is valid. This also lets a possible application called
       * IotHttpsClient_Disconnect() know that the connection is not busy, so the connection can be destroyed. */
      pHttpsResponse->reqFinishedSending = true;
  
      if( HTTPS_FAILED( status ) )
      {
          /* If the headers or body failed to send, then there should be no response expected from the server. */
          /* Cancel the response incase there is a response from the server. */
          _cancelResponse( pHttpsResponse );
          IotMutex_Lock( &( pHttpsConnection->connectionMutex ) );
  
          if( IotLink_IsLinked( &( pHttpsResponse->link ) ) )
          {
              IotDeQueue_Remove( &( pHttpsResponse->link ) );
          }
  
          IotMutex_Unlock( &( pHttpsConnection->connectionMutex ) );
  
          /* Set the error status in the sync workflow. */
          pHttpsResponse->syncStatus = status;
  
          /* Return the error status or cancel status to the application for an asynchronous workflow. */
          if( pHttpsRequest->isAsync && pHttpsRequest->pCallbacks->errorCallback )
          {
              pHttpsRequest->pCallbacks->errorCallback( pHttpsRequest->pUserPrivData, pHttpsRequest, NULL, status );
          }
  
          /* We close the connection on all network errors. All network errors in receiving the response, close the
           * connection. For consistency in behavior, if there is a network error in send, the connection should also be
           * closed. */
          if( status == IOT_HTTPS_NETWORK_ERROR )
          {
              IotLogDebug( "Disconnecting request %d.", pHttpsRequest );
              disconnectStatus = IotHttpsClient_Disconnect( pHttpsConnection );
  
              if( pHttpsRequest->isAsync && pHttpsRequest->pCallbacks->connectionClosedCallback )
              {
                  pHttpsRequest->pCallbacks->connectionClosedCallback( pHttpsRequest->pUserPrivData,
                                                                       pHttpsConnection,
                                                                       disconnectStatus );
              }
  
              if( HTTPS_FAILED( disconnectStatus ) )
              {
                  IotLogWarn( "Failed to disconnect request %d. Error code: %d.", pHttpsRequest, disconnectStatus );
              }
          }
          else
          {
              /* Because this request failed, the network receive callback may never be invoked to schedule other possible
               * requests in the queue. In order to avoid requests never getting scheduled on a connected connection,
               * the first item in the queue is scheduled if it can be. */
              IotMutex_Lock( &( pHttpsConnection->connectionMutex ) );
  
              /* Get the next item in the queue by removing this current (which is the first) and peeking at the head
               * again. */
              IotDeQueue_Remove( &( pHttpsRequest->link ) );
              pQItem = IotDeQueue_PeekHead( &( pHttpsConnection->reqQ ) );
              /* This current request is put back because it is removed again for all cases at the end of this routine. */
              IotDeQueue_EnqueueHead( &( pHttpsConnection->reqQ ), &( pHttpsRequest->link ) );
              IotMutex_Unlock( &( pHttpsConnection->connectionMutex ) );
  
              if( pQItem != NULL )
              {
                  /* Set this next request to send. */
                  pNextHttpsRequest = IotLink_Container( _httpsRequest_t, pQItem, link );
  
                  if( pNextHttpsRequest->scheduled == false )
                  {
                      IotLogDebug( "Request %d is next in the queue. Now scheduling a task to send the request.", pNextHttpsRequest );
                      scheduleStatus = _scheduleHttpsRequestSend( pNextHttpsRequest );
  
                      /* If there was an error with scheduling the new task, then report it. */
                      if( HTTPS_FAILED( scheduleStatus ) )
                      {
                          IotLogError( "Error scheduling HTTPS request %d. Error code: %d", pNextHttpsRequest, scheduleStatus );
  
                          if( pNextHttpsRequest->isAsync && pNextHttpsRequest->pCallbacks->errorCallback )
                          {
                              pNextHttpsRequest->pCallbacks->errorCallback( pNextHttpsRequest->pUserPrivData, pNextHttpsRequest, NULL, scheduleStatus );
                          }
                          else
                          {
                              pNextHttpsRequest->pHttpsResponse->syncStatus = scheduleStatus;
                          }
                      }
                  }
              }
          }
  
          /* Post to the response finished semaphore to unlock the application waiting on a synchronous request. */
          if( pHttpsRequest->isAsync == false )
          {
              IotSemaphore_Post( &( pHttpsResponse->respFinishedSem ) );
          }
          else if( pHttpsRequest->pCallbacks->responseCompleteCallback )
          {
              /* Call the response complete callback. We always call this even if we did not receive the response to
               * let the application know that the request has completed. */
              pHttpsRequest->pCallbacks->responseCompleteCallback( pHttpsRequest->pUserPrivData, NULL, status, 0 );
          }
      }
  
      IotMutex_Lock( &( pHttpsConnection->connectionMutex ) );
      /* Now that the current request is finished, we dequeue the current request from the queue. */
      IotDeQueue_DequeueHead( &( pHttpsConnection->reqQ ) );
      IotMutex_Unlock( &( pHttpsConnection->connectionMutex ) );
  
      /* This routine returns a void so there is no HTTPS_FUNCTION_CLEANUP_END();. */
  }
  
  /*-----------------------------------------------------------*/
  
  IotHttpsReturnCode_t _scheduleHttpsRequestSend( _httpsRequest_t * pHttpsRequest )
  {
      HTTPS_FUNCTION_ENTRY( IOT_HTTPS_OK );
  
      IotTaskPoolError_t taskPoolStatus = IOT_TASKPOOL_SUCCESS;
      _httpsConnection_t * pHttpsConnection = pHttpsRequest->pHttpsConnection;
  
      /* Set the request to scheduled even if scheduling fails. */
      pHttpsRequest->scheduled = true;
  
      taskPoolStatus = IotTaskPool_CreateJob( _sendHttpsRequest,
                                              ( void * ) ( pHttpsRequest ),
                                              &( pHttpsConnection->taskPoolJobStorage ),
                                              &( pHttpsConnection->taskPoolJob ) );
  
      /* Creating a task pool job should never fail when parameters are valid. */
      if( taskPoolStatus != IOT_TASKPOOL_SUCCESS )
      {
          IotLogError( "Error creating a taskpool job for request servicing. Error code: %d", taskPoolStatus );
          HTTPS_SET_AND_GOTO_CLEANUP( IOT_HTTPS_INTERNAL_ERROR );
      }
  
      taskPoolStatus = IotTaskPool_Schedule( IOT_SYSTEM_TASKPOOL, pHttpsConnection->taskPoolJob, 0 );
  
      if( taskPoolStatus != IOT_TASKPOOL_SUCCESS )
      {
          IotLogError( "Failed to schedule taskpool job. Error code: %d", taskPoolStatus );
          HTTPS_SET_AND_GOTO_CLEANUP( IOT_HTTPS_ASYNC_SCHEDULING_ERROR );
      }
  
      HTTPS_FUNCTION_EXIT_NO_CLEANUP();
  }
  
  /*-----------------------------------------------------------*/
  
  IotHttpsReturnCode_t _addRequestToConnectionReqQ( _httpsRequest_t * pHttpsRequest )
  {
      HTTPS_FUNCTION_ENTRY( IOT_HTTPS_OK );
  
      _httpsConnection_t * pHttpsConnection = pHttpsRequest->pHttpsConnection;
      bool scheduleRequest = false;
  
      /* Log information about the request*/
      IotLogDebug( "Now queueing request %d.", pHttpsRequest );
  
      if( pHttpsRequest->isNonPersistent )
      {
          IotLogDebug( "Request %d is non-persistent.", pHttpsRequest );
      }
      else
      {
          IotLogDebug( "Request %d is persistent. ", pHttpsRequest );
      }
  
      if( pHttpsRequest->isAsync )
      {
          IotLogDebug( " Request %d is asynchronous.", pHttpsRequest );
      }
      else
      {
          IotLogDebug( " Request %d is synchronous.", pHttpsRequest );
      }
  
      /* This is a new request and has not been scheduled if this routine is called. */
      pHttpsRequest->scheduled = false;
  
      /* Place the request into the queue. */
      IotMutex_Lock( &( pHttpsConnection->connectionMutex ) );
  
      /* If there is an active response, scheduling the next request at the same time may corrupt the workflow. Part of
       * the next response for the next request may be present in the currently receiving response's buffers. To avoid
       * this, check if there are pending responses to determine if this request should be scheduled right away or not.
       *
       * If there are other requests in the queue, and there are responses in the queue, then the network receive callback
       * will handle scheduling the next requests (or is already scheduled and currently sending). */
      if( ( IotDeQueue_IsEmpty( &( pHttpsConnection->reqQ ) ) ) &&
          ( IotDeQueue_IsEmpty( &( pHttpsConnection->respQ ) ) ) )
      {
          scheduleRequest = true;
      }
  
      /* Place into the connection's request to have a taskpool worker schedule to serve it later. */
      IotDeQueue_EnqueueTail( &( pHttpsConnection->reqQ ), &( pHttpsRequest->link ) );
      IotMutex_Unlock( &( pHttpsConnection->connectionMutex ) );
  
      if( scheduleRequest )
      {
          /* This routine schedules a task pool worker to send the request. If a worker is available immediately, then
           * the request is sent right away. */
          status = _scheduleHttpsRequestSend( pHttpsRequest );
  
          if( HTTPS_FAILED( status ) )
          {
              IotLogError( "Failed to schedule the request in the queue for request %d. Error code: %d", pHttpsRequest, status );
  
              /* If we fail to schedule the only request in the queue we should remove it. */
              IotMutex_Lock( &( pHttpsConnection->connectionMutex ) );
              IotDeQueue_Remove( &( pHttpsRequest->link ) );
              IotMutex_Unlock( &( pHttpsConnection->connectionMutex ) );
  
              HTTPS_GOTO_CLEANUP();
          }
      }
  
      HTTPS_FUNCTION_EXIT_NO_CLEANUP();
  }
  
  /*-----------------------------------------------------------*/
  
  static void _cancelRequest( _httpsRequest_t * pHttpsRequest )
  {
      pHttpsRequest->cancelled = true;
  }
  
  /*-----------------------------------------------------------*/
  
  static void _cancelResponse( _httpsResponse_t * pHttpsResponse )
  {
      pHttpsResponse->cancelled = true;
  }
  
  /*-----------------------------------------------------------*/
  
  IotHttpsReturnCode_t IotHttpsClient_Init( void )
  {
      HTTPS_FUNCTION_ENTRY( IOT_HTTPS_OK );
  
      /* This sets all member in the _httpParserSettings to zero. It does not return any errors. */
      http_parser_settings_init( &_httpParserSettings );
  
      /* Set the http-parser callbacks. */
      _httpParserSettings.on_message_begin = _httpParserOnMessageBeginCallback;
      _httpParserSettings.on_status = _httpParserOnStatusCallback;
      _httpParserSettings.on_header_field = _httpParserOnHeaderFieldCallback;
      _httpParserSettings.on_header_value = _httpParserOnHeaderValueCallback;
      _httpParserSettings.on_headers_complete = _httpParserOnHeadersCompleteCallback;
      _httpParserSettings.on_body = _httpParserOnBodyCallback;
      _httpParserSettings.on_message_complete = _httpParserOnMessageCompleteCallback;
  
  /* This code prints debugging information and is, therefore, compiled only when
   * log level is set to IOT_LOG_DEBUG. */
      #if ( LIBRARY_LOG_LEVEL == IOT_LOG_DEBUG )
          _httpParserSettings.on_chunk_header = _httpParserOnChunkHeaderCallback;
          _httpParserSettings.on_chunk_complete = _httpParserOnChunkCompleteCallback;
      #endif
      HTTPS_GOTO_CLEANUP();
      HTTPS_FUNCTION_EXIT_NO_CLEANUP();
  }
  
  /*-----------------------------------------------------------*/
  
  static IotHttpsReturnCode_t _initializeResponse( IotHttpsResponseHandle_t * pRespHandle,
                                                   IotHttpsResponseInfo_t * pRespInfo,
                                                   _httpsRequest_t * pHttpsRequest )
  {
      HTTPS_FUNCTION_ENTRY( IOT_HTTPS_OK );
  
      _httpsResponse_t * pHttpsResponse = NULL;
  
      HTTPS_ON_NULL_ARG_GOTO_CLEANUP( pRespInfo->userBuffer.pBuffer );
  
      /* Check of the user buffer is large enough for the response context + default headers. */
      HTTPS_ON_ARG_ERROR_MSG_GOTO_CLEANUP( pRespInfo->userBuffer.bufferLen >= responseUserBufferMinimumSize,
                                           IOT_HTTPS_INSUFFICIENT_MEMORY,
                                           "Buffer size is too small to initialize the response context. User buffer size: %d, required minimum size; %d.",
                                           pRespInfo->userBuffer.bufferLen,
                                           responseUserBufferMinimumSize );
  
      /* Initialize the corresponding response to this request. */
      pHttpsResponse = ( _httpsResponse_t * ) ( pRespInfo->userBuffer.pBuffer );
  
      /* Clear out the response user buffer. This is important because we
       * give the whole buffer to the parser as opposed to the actual content
       * length and rely on the parser to stop when a complete HTTP response
       * is found. To make sure that any data in the buffer which is not part
       * of the received HTTP response, does not get interpreted as part of
       * the HTTP repose, we zero out the buffer here. */
      memset( pRespInfo->userBuffer.pBuffer, 0, pRespInfo->userBuffer.bufferLen );
  
      pHttpsResponse->pHeaders = ( uint8_t * ) ( pHttpsResponse ) + sizeof( _httpsResponse_t );
      pHttpsResponse->pHeadersEnd = ( uint8_t * ) ( pHttpsResponse ) + pRespInfo->userBuffer.bufferLen;
      pHttpsResponse->pHeadersCur = pHttpsResponse->pHeaders;
  
      if( pHttpsRequest->isAsync )
      {
          pHttpsResponse->isAsync = true;
  
          /* For an asynchronous request the response body is provided by the application in the
           * IotHttpsCallbacks_t.readReadyCallback(). These pointers will be updated when IotHttpsClient_ReadResponseBody()
           * is invoked. */
          pHttpsResponse->pBody = NULL;
          pHttpsResponse->pBodyCur = NULL;
          pHttpsResponse->pBodyEnd = NULL;
  
          pHttpsResponse->pCallbacks = pHttpsRequest->pCallbacks;
          pHttpsResponse->pUserPrivData = pHttpsRequest->pUserPrivData;
      }
      else
      {
          pHttpsResponse->isAsync = false;
          /* The request body pointer is allowed to be NULL. u.pSyncInfo was checked for NULL earlier in this function. */
          pHttpsResponse->pBody = pRespInfo->pSyncInfo->pBody;
          pHttpsResponse->pBodyCur = pHttpsResponse->pBody;
          pHttpsResponse->pBodyEnd = pHttpsResponse->pBody + pRespInfo->pSyncInfo->bodyLen;
  
          /* Clear out the body bufffer. This is important because we give the
           * whole buffer to the parser as opposed to the actual content length and
           * rely on the parser to stop when a complete HTTP response is found. To
           * make sure that any data in the buffer which is not part of the received
           * HTTP response, does not get interpreted as part of the HTTP repose, we
           * zero out the buffer here. */
          memset( pRespInfo->pSyncInfo->pBody, 0, pRespInfo->pSyncInfo->bodyLen );
      }
  
      /* Reinitialize the parser and set the fill buffer state to empty. This does not return any errors. */
      http_parser_init( &( pHttpsResponse->httpParserInfo.responseParser ), HTTP_RESPONSE );
      http_parser_init( &( pHttpsResponse->httpParserInfo.readHeaderParser ), HTTP_RESPONSE );
      /* Set the third party http parser function. */
      pHttpsResponse->httpParserInfo.parseFunc = http_parser_execute;
      pHttpsResponse->httpParserInfo.readHeaderParser.data = ( void * ) ( pHttpsResponse );
      pHttpsResponse->httpParserInfo.responseParser.data = ( void * ) ( pHttpsResponse );
  
      pHttpsResponse->status = 0;
      pHttpsResponse->method = pHttpsRequest->method;
      pHttpsResponse->parserState = PARSER_STATE_NONE;
      pHttpsResponse->bufferProcessingState = PROCESSING_STATE_NONE;
      pHttpsResponse->pReadHeaderField = NULL;
      pHttpsResponse->readHeaderFieldLength = 0;
      pHttpsResponse->pReadHeaderValue = NULL;
      pHttpsResponse->readHeaderValueLength = 0;
      pHttpsResponse->foundHeaderField = 0;
      pHttpsResponse->pHttpsConnection = NULL;
  
      pHttpsResponse->pBodyInHeaderBuf = NULL;
      pHttpsResponse->pBodyCurInHeaderBuf = NULL;
      pHttpsResponse->bodyRxStatus = IOT_HTTPS_OK;
      pHttpsResponse->cancelled = false;
      pHttpsResponse->syncStatus = IOT_HTTPS_OK;
      /* There is no request associated with this response right now, so it is finished sending. */
      pHttpsResponse->reqFinishedSending = true;
      pHttpsResponse->isNonPersistent = pHttpsRequest->isNonPersistent;
  
      /* Set the response handle to return. */
      *pRespHandle = pHttpsResponse;
  
      HTTPS_FUNCTION_CLEANUP_BEGIN();
  
      if( HTTPS_FAILED( status ) )
      {
          pRespHandle = NULL;
      }
  
      HTTPS_FUNCTION_CLEANUP_END();
  }
  
  /*-----------------------------------------------------------*/
  
  void IotHttpsClient_Deinit( void )
  {
      /* There is nothing to de-initialize here as of now. */
  }
  
  /* --------------------------------------------------------- */
  
  IotHttpsReturnCode_t IotHttpsClient_Connect( IotHttpsConnectionHandle_t * pConnHandle,
                                               IotHttpsConnectionInfo_t * pConnInfo )
  {
      HTTPS_FUNCTION_ENTRY( IOT_HTTPS_OK );
  
      /* Check for NULL parameters in a public API. */
      HTTPS_ON_NULL_ARG_GOTO_CLEANUP( pConnHandle );
      HTTPS_ON_NULL_ARG_GOTO_CLEANUP( pConnInfo );
  
      /* If a valid connection handle is passed in. */
      if( *pConnHandle != NULL )
      {
          /* If the handle in a connected state, then we want to disconnect before reconnecting. The ONLY way to put the
           * handle is a disconnect state is to call IotHttpsClient_Disconnect(). */
          if( ( *pConnHandle )->isConnected )
          {
              status = IotHttpsClient_Disconnect( *pConnHandle );
  
              if( HTTPS_FAILED( status ) )
              {
                  IotLogError( "Error disconnecting a connected *pConnHandle passed to IotHttpsClient_Connect().Error code %d", status );
                  *pConnHandle = NULL;
                  HTTPS_GOTO_CLEANUP();
              }
          }
      }
  
      /* Connect to the server now. Initialize all resources needed for the connection context as well here. */
      status = _createHttpsConnection( pConnHandle, pConnInfo );
  
      if( HTTPS_FAILED( status ) )
      {
          IotLogError( "Error in IotHttpsClient_Connect(). Error code %d.", status );
      }
  
      HTTPS_FUNCTION_EXIT_NO_CLEANUP();
  }
  
  /*-----------------------------------------------------------*/
  
  IotHttpsReturnCode_t IotHttpsClient_Disconnect( IotHttpsConnectionHandle_t connHandle )
  {
      HTTPS_FUNCTION_ENTRY( IOT_HTTPS_OK );
  
      _httpsRequest_t * pHttpsRequest = NULL;
      _httpsResponse_t * pHttpsResponse = NULL;
      IotLink_t * pRespItem = NULL;
      IotLink_t * pReqItem = NULL;
  
      HTTPS_ON_NULL_ARG_GOTO_CLEANUP( connHandle );
  
      /* If this routine is currently is progress by another thread, for instance the taskpool worker that received a
       * network error after sending, then return right away because connection resources are being used. */
      if( IotMutex_TryLock( &( connHandle->connectionMutex ) ) == false )
      {
          HTTPS_SET_AND_GOTO_CLEANUP( IOT_HTTPS_BUSY );
      }
  
      /* Do not attempt to disconnect an already disconnected connection.
       * It can happen when a user calls this functions and we return IOT_HTTPS_BUSY. */
      if( connHandle->isConnected )
      {
          /* Mark the network as disconnected whether the disconnect passes or not. */
          connHandle->isConnected = false;
          _networkDisconnect( connHandle );
      }
  
      /* If there is a response in the connection's response queue and the associated request has not finished sending,
       * then we cannot destroy the connection until it finishes. */
      pRespItem = IotDeQueue_DequeueHead( &( connHandle->respQ ) );
  
      if( pRespItem != NULL )
      {
          pHttpsResponse = IotLink_Container( _httpsResponse_t, pRespItem, link );
  
          if( pHttpsResponse->reqFinishedSending == false )
          {
              IotLogError( "Connection is in use. Disconnected, but cannot destroy the connection." );
              status = IOT_HTTPS_BUSY;
  
              /* The request is busy, to as quickly as possible allow a successful retry call of this function we must
               * cancel the busy request which is the first in the queue. */
              pReqItem = IotDeQueue_PeekHead( &( connHandle->reqQ ) );
  
              if( pReqItem != NULL )
              {
                  pHttpsRequest = IotLink_Container( _httpsRequest_t, pReqItem, link );
                  _cancelRequest( pHttpsRequest );
              }
  
              /* We set the status as busy, but we do not goto the cleanup right away because we still want to remove
               * all pending requests. */
          }
  
          /* Delete all possible pending responses. (This is defensive.) */
          IotDeQueue_RemoveAll( &( connHandle->respQ ), NULL, 0 );
  
          /* Put the response that was dequeued back so that the application can call this function again to check later
           * that is exited and marked itself as finished sending.
           * If during the last check and this check reqFinishedSending gets set to true, that is OK because on the next
           * call to this routine, the disconnect will succeed. */
          if( pHttpsResponse->reqFinishedSending == false )
          {
              IotDeQueue_EnqueueHead( &( connHandle->respQ ), pRespItem );
          }
      }
  
      /* Remove all pending requests. If this routine is called from the application context and there is a
       * network receive callback in process, this routine will wait in _networkDestroy until that routine returns.
       * If this is routine is called from the network receive callback context, then the destroy happens after the
       * network receive callback context returns. */
      IotDeQueue_RemoveAll( &( connHandle->reqQ ), NULL, 0 );
  
      /* Do not attempt to destroy an already destroyed connection. This can happen when the user calls this function and
       * IOT_HTTPS_BUSY is returned. */
      if( HTTPS_SUCCEEDED( status ) )
      {
          if( connHandle->isDestroyed == false )
          {
              connHandle->isDestroyed = true;
              _networkDestroy( connHandle );
          }
      }
  
      HTTPS_FUNCTION_CLEANUP_BEGIN();
  
      /* This function is no longer in process, so disconnecting is no longer in process. This signals to the retry
       * on this function that it can proceed with the disconnecting activities. */
      if( connHandle != NULL )
      {
          IotMutex_Unlock( &( connHandle->connectionMutex ) );
      }
  
      HTTPS_FUNCTION_CLEANUP_END();
  }
  
  /*-----------------------------------------------------------*/
  
  IotHttpsReturnCode_t IotHttpsClient_InitializeRequest( IotHttpsRequestHandle_t * pReqHandle,
                                                         IotHttpsRequestInfo_t * pReqInfo )
  {
      HTTPS_FUNCTION_ENTRY( IOT_HTTPS_OK );
  
      _httpsRequest_t * pHttpsRequest = NULL;
      size_t additionalLength = 0;
      size_t spaceLen = 1;
      char * pSpace = " ";
      size_t httpsMethodLen = 0;
      size_t httpsProtocolVersionLen = FAST_MACRO_STRLEN( HTTPS_PROTOCOL_VERSION );
  
      /* Check for NULL parameters in the public API. */
      HTTPS_ON_NULL_ARG_GOTO_CLEANUP( pReqHandle );
      HTTPS_ON_NULL_ARG_GOTO_CLEANUP( pReqInfo );
      HTTPS_ON_NULL_ARG_GOTO_CLEANUP( pReqInfo->userBuffer.pBuffer );
      HTTPS_ON_NULL_ARG_GOTO_CLEANUP( pReqInfo->pHost );
  
      if( pReqInfo->isAsync )
      {
          HTTPS_ON_NULL_ARG_GOTO_CLEANUP( pReqInfo->u.pAsyncInfo );
      }
      else
      {
          HTTPS_ON_NULL_ARG_GOTO_CLEANUP( pReqInfo->u.pSyncInfo );
      }
  
      /* Check of the user buffer is large enough for the request context + default headers. */
      HTTPS_ON_ARG_ERROR_MSG_GOTO_CLEANUP( pReqInfo->userBuffer.bufferLen >= requestUserBufferMinimumSize,
                                           IOT_HTTPS_INSUFFICIENT_MEMORY,
                                           "Buffer size is too small to initialize the request context. User buffer size: %d, required minimum size; %d.",
                                           pReqInfo->userBuffer.bufferLen,
                                           requestUserBufferMinimumSize );
  
      /* Set the request contet to the start of the userbuffer. */
      pHttpsRequest = ( _httpsRequest_t * ) ( pReqInfo->userBuffer.pBuffer );
      /* Clear out the user buffer. */
      memset( pReqInfo->userBuffer.pBuffer, 0, pReqInfo->userBuffer.bufferLen );
  
      /* Set the start of the headers to the end of the request context in the user buffer. */
      pHttpsRequest->pHeaders = ( uint8_t * ) pHttpsRequest + sizeof( _httpsRequest_t );
      pHttpsRequest->pHeadersEnd = ( uint8_t * ) pHttpsRequest + pReqInfo->userBuffer.bufferLen;
      pHttpsRequest->pHeadersCur = pHttpsRequest->pHeaders;
  
      /* Get the length of the HTTP method. */
      httpsMethodLen = strlen( _pHttpsMethodStrings[ pReqInfo->method ] );
  
      /* Add the request line to the header buffer. */
      additionalLength = httpsMethodLen +          \
                         spaceLen +                \
                         pReqInfo->pathLen +       \
                         spaceLen +                \
                         httpsProtocolVersionLen + \
                         HTTPS_END_OF_HEADER_LINES_INDICATOR_LENGTH;
  
      if( ( additionalLength + pHttpsRequest->pHeadersCur ) > ( pHttpsRequest->pHeadersEnd ) )
      {
          IotLogError( "Request line does not fit into the request user buffer: \"%s %.*s HTTP/1.1\\r\\n\" . ",
                       _pHttpsMethodStrings[ pReqInfo->method ],
                       pReqInfo->pathLen,
                       pReqInfo->pPath );
          IotLogError( "The length needed is %d and the space available is %d.", additionalLength, pHttpsRequest->pHeadersEnd - pHttpsRequest->pHeadersCur );
          HTTPS_SET_AND_GOTO_CLEANUP( IOT_HTTPS_INSUFFICIENT_MEMORY );
      }
  
      /* Write "<METHOD> <PATH> HTTP/1.1\r\n" to the start of the header space. */
      memcpy( pHttpsRequest->pHeadersCur, _pHttpsMethodStrings[ pReqInfo->method ], httpsMethodLen );
      pHttpsRequest->pHeadersCur += httpsMethodLen;
      memcpy( pHttpsRequest->pHeadersCur, pSpace, spaceLen );
      pHttpsRequest->pHeadersCur += spaceLen;
  
      if( pReqInfo->pPath == NULL )
      {
          pReqInfo->pPath = HTTPS_EMPTY_PATH;
          pReqInfo->pathLen = FAST_MACRO_STRLEN( HTTPS_EMPTY_PATH );
      }
  
      memcpy( pHttpsRequest->pHeadersCur, pReqInfo->pPath, pReqInfo->pathLen );
      pHttpsRequest->pHeadersCur += pReqInfo->pathLen;
      memcpy( pHttpsRequest->pHeadersCur, pSpace, spaceLen );
      pHttpsRequest->pHeadersCur += spaceLen;
      memcpy( pHttpsRequest->pHeadersCur, HTTPS_PROTOCOL_VERSION, httpsProtocolVersionLen );
      pHttpsRequest->pHeadersCur += httpsProtocolVersionLen;
      memcpy( pHttpsRequest->pHeadersCur, HTTPS_END_OF_HEADER_LINES_INDICATOR, HTTPS_END_OF_HEADER_LINES_INDICATOR_LENGTH );
      pHttpsRequest->pHeadersCur += HTTPS_END_OF_HEADER_LINES_INDICATOR_LENGTH;
  
      /* Add the User-Agent header. */
      status = _addHeader( pHttpsRequest, HTTPS_USER_AGENT_HEADER, FAST_MACRO_STRLEN( HTTPS_USER_AGENT_HEADER ), IOT_HTTPS_USER_AGENT, FAST_MACRO_STRLEN( IOT_HTTPS_USER_AGENT ) );
  
      if( HTTPS_FAILED( status ) )
      {
          IotLogError( "Failed to write header to the request user buffer: \"User-Agent: %s\\r\\n\" . Error code: %d",
                       IOT_HTTPS_USER_AGENT,
                       status );
          HTTPS_GOTO_CLEANUP();
      }
  
      status = _addHeader( pHttpsRequest, HTTPS_HOST_HEADER, FAST_MACRO_STRLEN( HTTPS_HOST_HEADER ), pReqInfo->pHost, pReqInfo->hostLen );
  
      if( HTTPS_FAILED( status ) )
      {
          IotLogError( "Failed to write \"Host: %.*s\\r\\n\" to the request user buffer. Error code: %d",
                       pReqInfo->hostLen,
                       pReqInfo->pHost,
                       status );
          HTTPS_GOTO_CLEANUP();
      }
  
      if( pReqInfo->isAsync )
      {
          pHttpsRequest->isAsync = true;
          /* If this is an asynchronous request then save the callbacks to use. */
          pHttpsRequest->pCallbacks = &( pReqInfo->u.pAsyncInfo->callbacks );
          pHttpsRequest->pUserPrivData = pReqInfo->u.pAsyncInfo->pPrivData;
          /* The body pointer and body length will be filled in when the application sends data in the writeCallback. */
          pHttpsRequest->pBody = NULL;
          pHttpsRequest->bodyLength = 0;
      }
      else
      {
          pHttpsRequest->isAsync = false;
          /* Set the HTTP request entity body. This is allowed to be NULL for no body like for a GET request. */
          pHttpsRequest->pBody = pReqInfo->u.pSyncInfo->pBody;
          pHttpsRequest->bodyLength = pReqInfo->u.pSyncInfo->bodyLen;
      }
  
      /* Save the method of this request. */
      pHttpsRequest->method = pReqInfo->method;
      /* Set the connection persistence flag for keeping the connection open after receiving a response. */
      pHttpsRequest->isNonPersistent = pReqInfo->isNonPersistent;
      /* Initialize the request cancellation. */
      pHttpsRequest->cancelled = false;
      /* Initialize the status of sending the body over the network in a possible asynchronous request. */
      pHttpsRequest->bodyTxStatus = IOT_HTTPS_OK;
      /* This is a new request and therefore not scheduled yet. */
      pHttpsRequest->scheduled = false;
  
      /* Set the request handle to return. */
      *pReqHandle = pHttpsRequest;
  
      HTTPS_FUNCTION_CLEANUP_BEGIN();
  
      if( HTTPS_FAILED( status ) && ( pReqHandle != NULL ) )
      {
          /* Set the request handle to return to NULL, if we failed anywhere. */
          *pReqHandle = NULL;
      }
  
      HTTPS_FUNCTION_CLEANUP_END();
  }
  
  /*-----------------------------------------------------------*/
  
  IotHttpsReturnCode_t IotHttpsClient_AddHeader( IotHttpsRequestHandle_t reqHandle,
                                                 char * pName,
                                                 uint32_t nameLen,
                                                 char * pValue,
                                                 uint32_t valueLen )
  {
      HTTPS_FUNCTION_ENTRY( IOT_HTTPS_OK );
  
      /* Check for NULL pointer paramters. */
      HTTPS_ON_NULL_ARG_GOTO_CLEANUP( pName );
      HTTPS_ON_NULL_ARG_GOTO_CLEANUP( pValue );
      HTTPS_ON_NULL_ARG_GOTO_CLEANUP( reqHandle );
  
      /* Check for name long enough for header length calculation to overflow */
      HTTPS_ON_ARG_ERROR_MSG_GOTO_CLEANUP( nameLen <= ( UINT32_MAX >> 2 ),
                                           IOT_HTTPS_INVALID_PARAMETER,
                                           "Attempting to generate headers with name length %d > %d. This is not allowed.",
                                           nameLen, UINT32_MAX >> 2 );
  
      /* Check for value long enough for header length calculation to overflow */
      HTTPS_ON_ARG_ERROR_MSG_GOTO_CLEANUP( valueLen <= ( UINT32_MAX >> 2 ),
                                           IOT_HTTPS_INVALID_PARAMETER,
                                           "Attempting to generate headers with value length %d > %d. This is not allowed.",
                                           valueLen, UINT32_MAX >> 2 );
  
      /* Check for auto-generated header "Content-Length". This header is created and send automatically when right before
       * request body is sent on the network. */
      HTTPS_ON_ARG_ERROR_MSG_GOTO_CLEANUP( strncmp( pName, HTTPS_CONTENT_LENGTH_HEADER, FAST_MACRO_STRLEN( HTTPS_CONTENT_LENGTH_HEADER ) ) != 0,
                                           IOT_HTTPS_INVALID_PARAMETER,
                                           "Attempting to add auto-generated header %s. This is not allowed.",
                                           HTTPS_CONTENT_LENGTH_HEADER );
  
      /* Check for auto-generated header "Connection". This header is created and send automatically when right before
       * request body is sent on the network. */
      HTTPS_ON_ARG_ERROR_MSG_GOTO_CLEANUP( strncmp( pName, HTTPS_CONNECTION_HEADER, FAST_MACRO_STRLEN( HTTPS_CONNECTION_HEADER ) ) != 0,
                                           IOT_HTTPS_INVALID_PARAMETER,
                                           "Attempting to add auto-generated header %s. This is not allowed.",
                                           HTTPS_CONNECTION_HEADER );
  
      /* Check for auto-generated header "Host". This header is created and placed into the header buffer space
       * in IotHttpClient_InitializeRequest(). */
      HTTPS_ON_ARG_ERROR_MSG_GOTO_CLEANUP( strncmp( pName, HTTPS_HOST_HEADER, FAST_MACRO_STRLEN( HTTPS_HOST_HEADER ) ) != 0,
                                           IOT_HTTPS_INVALID_PARAMETER,
                                           "Attempting to add auto-generated header %s. This is not allowed.",
                                           HTTPS_HOST_HEADER );
  
      /* Check for auto-generated header "User-Agent". This header is created and placed into the header buffer space
       * in IotHttpClient_InitializeRequest(). */
      HTTPS_ON_ARG_ERROR_MSG_GOTO_CLEANUP( strncmp( pName, HTTPS_USER_AGENT_HEADER, FAST_MACRO_STRLEN( HTTPS_USER_AGENT_HEADER ) ) != 0,
                                           IOT_HTTPS_INVALID_PARAMETER,
                                           "Attempting to add auto-generated header %s. This is not allowed.",
                                           HTTPS_USER_AGENT_HEADER );
  
  
      status = _addHeader( reqHandle, pName, nameLen, pValue, valueLen );
  
      if( HTTPS_FAILED( status ) )
      {
          IotLogError( "Error in IotHttpsClient_AddHeader(), error code %d.", status );
          HTTPS_GOTO_CLEANUP();
      }
  
      HTTPS_FUNCTION_EXIT_NO_CLEANUP();
  }
  
  /*-----------------------------------------------------------*/
  
  IotHttpsReturnCode_t IotHttpsClient_SendSync( IotHttpsConnectionHandle_t connHandle,
                                                IotHttpsRequestHandle_t reqHandle,
                                                IotHttpsResponseHandle_t * pRespHandle,
                                                IotHttpsResponseInfo_t * pRespInfo,
                                                uint32_t timeoutMs )
  {
      HTTPS_FUNCTION_ENTRY( IOT_HTTPS_OK );
  
      bool respFinishedSemCreated = false;
      _httpsResponse_t * pHttpsResponse = NULL;
  
      /* Parameter checks. */
      HTTPS_ON_NULL_ARG_GOTO_CLEANUP( connHandle );
      HTTPS_ON_NULL_ARG_GOTO_CLEANUP( reqHandle );
      HTTPS_ON_NULL_ARG_GOTO_CLEANUP( pRespHandle );
      HTTPS_ON_NULL_ARG_GOTO_CLEANUP( pRespInfo );
      /* Stop the application from scheduling requests on a closed connection. */
      HTTPS_ON_ARG_ERROR_GOTO_CLEANUP( connHandle->isConnected );
  
      /* If an asynchronous request/response is configured, that is invalid for this API. */
      if( reqHandle->isAsync )
      {
          IotLogError( "Called IotHttpsClient_SendSync on an asynchronous configured request." );
          HTTPS_SET_AND_GOTO_CLEANUP( IOT_HTTPS_INVALID_PARAMETER );
      }
  
      /* Initialize the response handle to return. */
      status = _initializeResponse( pRespHandle, pRespInfo, reqHandle );
  
      if( HTTPS_FAILED( status ) )
      {
          IotLogError( "Failed to initialize the response on the synchronous request %d.", reqHandle );
          HTTPS_GOTO_CLEANUP();
      }
  
      /* Set the internal response to use. */
      pHttpsResponse = *pRespHandle;
  
      /* The implicit connection passed and we need to the set the connection handle in the request and response. */
      reqHandle->pHttpsConnection = connHandle;
      pHttpsResponse->pHttpsConnection = connHandle;
  
      /* Create the semaphore used to wait on the response to finish being received. */
      respFinishedSemCreated = IotSemaphore_Create( &( pHttpsResponse->respFinishedSem ), 0 /* initialValue */, 1 /* maxValue */ );
  
      if( respFinishedSemCreated == false )
      {
          IotLogError( "Failed to create an internal semaphore." );
          HTTPS_SET_AND_GOTO_CLEANUP( IOT_HTTPS_INTERNAL_ERROR );
      }
  
      /* Associate the response to the request so that we can schedule it to be received when the request gets scheduled to send. */
      reqHandle->pHttpsResponse = pHttpsResponse;
  
      /* Schedule this request to be sent by adding it to the connection's request queue. */
      status = _addRequestToConnectionReqQ( reqHandle );
  
      if( HTTPS_FAILED( status ) )
      {
          IotLogError( "Failed to schedule the synchronous request. Error code: %d", status );
          HTTPS_GOTO_CLEANUP();
      }
  
      /* Wait for the request to finish. */
      if( timeoutMs == 0 )
      {
          IotSemaphore_Wait( &( pHttpsResponse->respFinishedSem ) );
      }
      else
      {
          if( IotSemaphore_TimedWait( &( pHttpsResponse->respFinishedSem ), timeoutMs ) == false )
          {
              IotLogError( "Timed out waiting for the synchronous request to finish. Timeout ms: %d", timeoutMs );
              _cancelRequest( reqHandle );
              HTTPS_SET_AND_GOTO_CLEANUP( IOT_HTTPS_TIMEOUT_ERROR );
          }
      }
  
      HTTPS_FUNCTION_CLEANUP_BEGIN();
  
      if( respFinishedSemCreated )
      {
          IotSemaphore_Destroy( &( pHttpsResponse->respFinishedSem ) );
      }
  
      /* If the syncStatus is anything other than IOT_HTTPS_OK, then the request was scheduled. */
      if( ( pHttpsResponse != NULL ) && HTTPS_FAILED( pHttpsResponse->syncStatus ) )
      {
          status = pHttpsResponse->syncStatus;
      }
  
      if( HTTPS_FAILED( status ) )
      {
          if( pRespHandle != NULL )
          {
              *pRespHandle = NULL;
          }
  
          IotLogError( "IotHttpsClient_SendSync() failed." );
      }
  
      HTTPS_FUNCTION_CLEANUP_END();
  }
  
  /*-----------------------------------------------------------*/
  
  IotHttpsReturnCode_t IotHttpsClient_WriteRequestBody( IotHttpsRequestHandle_t reqHandle,
                                                        uint8_t * pBuf,
                                                        uint32_t len,
                                                        int isComplete )
  {
      HTTPS_FUNCTION_ENTRY( IOT_HTTPS_OK );
  
      HTTPS_ON_NULL_ARG_GOTO_CLEANUP( reqHandle );
      HTTPS_ON_NULL_ARG_GOTO_CLEANUP( pBuf );
  
      /* This function is not valid for a synchronous response. Applications need to configure the request body in
       * IotHttpsRequestInfo_t.pSyncInfo_t.reqData before calling IotHttpsClient_SendSync(). */
      HTTPS_ON_ARG_ERROR_GOTO_CLEANUP( reqHandle->isAsync );
      HTTPS_ON_ARG_ERROR_MSG_GOTO_CLEANUP( isComplete == 1,
                                           IOT_HTTPS_NOT_SUPPORTED,
                                           "isComplete must be 1 in IotHttpsClient_WriteRequestBody() for the current version of the HTTPS Client library." );
  
      /* If the bodyLength is greater than 0, then we already called this function and we need to enforce that this
       * function must only be called once. We only call this function once so that we can calculate the Content-Length. */
      if( reqHandle->bodyLength > 0 )
      {
          IotLogError( "Error this function must be called once with the data needed to send. Variable length HTTP "
                       "request body is not supported in this library." );
          HTTPS_SET_AND_GOTO_CLEANUP( IOT_HTTPS_MESSAGE_FINISHED );
      }
  
      /* Set the pointer to the body and the length for the content-length calculation. */
      reqHandle->pBody = ( uint8_t * ) pBuf;
      reqHandle->bodyLength = len;
  
      /* We send the HTTPS headers and body in this function so that the application has the freedom to specify a body
       * that may be buffer on stack. */
      status = _sendHttpsHeadersAndBody( reqHandle->pHttpsConnection, reqHandle );
  
      if( HTTPS_FAILED( status ) )
      {
          IotLogError( "Failed to send the headers and body. Error code %d.", status );
          HTTPS_GOTO_CLEANUP();
      }
  
      HTTPS_FUNCTION_CLEANUP_BEGIN();
  
      if( reqHandle != NULL )
      {
          reqHandle->bodyTxStatus = status;
      }
  
      HTTPS_FUNCTION_CLEANUP_END();
  }
  
  /*-----------------------------------------------------------*/
  
  IotHttpsReturnCode_t IotHttpsClient_ReadResponseBody( IotHttpsResponseHandle_t respHandle,
                                                        uint8_t * pBuf,
                                                        uint32_t * pLen )
  {
      HTTPS_FUNCTION_ENTRY( IOT_HTTPS_OK );
  
      uint32_t bodyLengthInHeaderBuf = 0;
  
      HTTPS_ON_NULL_ARG_GOTO_CLEANUP( respHandle );
      HTTPS_ON_NULL_ARG_GOTO_CLEANUP( pBuf );
      HTTPS_ON_NULL_ARG_GOTO_CLEANUP( pLen );
      HTTPS_ON_ARG_ERROR_GOTO_CLEANUP( respHandle->isAsync );
  
      /* Set the current body in the respHandle to use in _receiveHttpsBody(). _receiveHttpsBody is generic
       *  to both async and sync request/response handling. In the sync version the body is configured during
       *  initializing the request. In the async version the body is given in this function on the fly. */
      respHandle->pBody = pBuf;
      respHandle->pBodyCur = respHandle->pBody;
      respHandle->pBodyEnd = respHandle->pBodyCur + *pLen;
  
      /* When there is part of the body in the header pBuffer. We need to move that data to this body pBuffer
       *  provided in this fuction. */
      bodyLengthInHeaderBuf = respHandle->pBodyCurInHeaderBuf - respHandle->pBodyInHeaderBuf;
  
      if( bodyLengthInHeaderBuf > 0 )
      {
          uint32_t copyLength = bodyLengthInHeaderBuf > *pLen ? *pLen : bodyLengthInHeaderBuf;
          memcpy( respHandle->pBodyCur, respHandle->pBodyInHeaderBuf, copyLength );
          respHandle->pBodyCur += copyLength;
  
          /* This function may be called multiple times until all of the body that may be present in the header buffer is
           * moved out. */
          respHandle->pBodyInHeaderBuf += copyLength;
      }
  
      /* If there is room in the body buffer just provided by the application and we have not completed the current
       * HTTP response message, then try to receive more body. */
      if( ( ( respHandle->pBodyEnd - respHandle->pBodyCur ) > 0 ) && ( respHandle->parserState < PARSER_STATE_BODY_COMPLETE ) )
      {
          status = _receiveHttpsBody( respHandle->pHttpsConnection, respHandle );
  
          if( HTTPS_FAILED( status ) )
          {
              IotLogError( "Failed to receive the HTTP response body on the network. Error code: %d.", status );
              HTTPS_GOTO_CLEANUP();
          }
      }
  
      *pLen = respHandle->pBodyCur - respHandle->pBody;
  
      HTTPS_FUNCTION_CLEANUP_BEGIN();
  
      if( respHandle != NULL )
      {
          respHandle->bodyRxStatus = status;
      }
  
      HTTPS_FUNCTION_CLEANUP_END();
  }
  
  /*-----------------------------------------------------------*/
  
  IotHttpsReturnCode_t IotHttpsClient_CancelRequestAsync( IotHttpsRequestHandle_t reqHandle )
  {
      HTTPS_FUNCTION_ENTRY( IOT_HTTPS_OK );
  
      HTTPS_ON_NULL_ARG_GOTO_CLEANUP( reqHandle );
  
      _cancelRequest( reqHandle );
  
      HTTPS_FUNCTION_EXIT_NO_CLEANUP();
  }
  
  /*-----------------------------------------------------------*/
  
  IotHttpsReturnCode_t IotHttpsClient_CancelResponseAsync( IotHttpsResponseHandle_t respHandle )
  {
      HTTPS_FUNCTION_ENTRY( IOT_HTTPS_OK );
  
      HTTPS_ON_NULL_ARG_GOTO_CLEANUP( respHandle );
  
      _cancelResponse( respHandle );
  
      HTTPS_FUNCTION_EXIT_NO_CLEANUP();
  }
  
  
  /*-----------------------------------------------------------*/
  
  IotHttpsReturnCode_t IotHttpsClient_SendAsync( IotHttpsConnectionHandle_t connHandle,
                                                 IotHttpsRequestHandle_t reqHandle,
                                                 IotHttpsResponseHandle_t * pRespHandle,
                                                 IotHttpsResponseInfo_t * pRespInfo )
  {
      HTTPS_FUNCTION_ENTRY( IOT_HTTPS_OK );
  
      HTTPS_ON_NULL_ARG_GOTO_CLEANUP( connHandle );
      HTTPS_ON_NULL_ARG_GOTO_CLEANUP( reqHandle );
      HTTPS_ON_NULL_ARG_GOTO_CLEANUP( pRespHandle );
      HTTPS_ON_NULL_ARG_GOTO_CLEANUP( pRespInfo );
      HTTPS_ON_ARG_ERROR_GOTO_CLEANUP( reqHandle->isAsync );
      /* Stop the application from scheduling requests on a closed connection. */
      HTTPS_ON_ARG_ERROR_GOTO_CLEANUP( connHandle->isConnected );
  
      /* Initialize the response handle to return. */
      status = _initializeResponse( pRespHandle, pRespInfo, reqHandle );
  
      if( HTTPS_FAILED( status ) )
      {
          IotLogError( "Failed to initialize the response on the synchronous request %d.", reqHandle );
          HTTPS_GOTO_CLEANUP();
      }
  
      /* Set the connection handle in the request handle so that we can use it in the _writeRequestBody() callback. */
      reqHandle->pHttpsConnection = connHandle;
  
      /* Set the connection handle in the response handle sp that we can use it in the _readReadyCallback() callback. */
      ( *pRespHandle )->pHttpsConnection = connHandle;
  
      /* Associate the response to the request so that we can schedule it to be received when the request gets scheduled to send. */
      reqHandle->pHttpsResponse = *pRespHandle;
  
      /* Add the request to the connection's request queue. */
      status = _addRequestToConnectionReqQ( reqHandle );
  
      if( HTTPS_FAILED( status ) )
      {
          IotLogError( "Failed to add request %d to the connection's request queue. Error code: %d.", reqHandle, status );
          HTTPS_GOTO_CLEANUP();
      }
  
      HTTPS_FUNCTION_EXIT_NO_CLEANUP();
  }
  
  /*-----------------------------------------------------------*/
  
  IotHttpsReturnCode_t IotHttpsClient_ReadResponseStatus( IotHttpsResponseHandle_t respHandle,
                                                          uint16_t * pStatus )
  {
      HTTPS_FUNCTION_ENTRY( IOT_HTTPS_OK );
  
      HTTPS_ON_NULL_ARG_GOTO_CLEANUP( respHandle );
      HTTPS_ON_NULL_ARG_GOTO_CLEANUP( pStatus );
  
      HTTPS_ON_ARG_ERROR_MSG_GOTO_CLEANUP( respHandle->status != 0,
                                           IOT_HTTPS_NOT_FOUND,
                                           "The HTTP response status was not found in the HTTP response header buffer." );
  
      *pStatus = respHandle->status;
  
      HTTPS_FUNCTION_EXIT_NO_CLEANUP();
  }
  
  /*-----------------------------------------------------------*/
  
  IotHttpsReturnCode_t IotHttpsClient_ReadHeader( IotHttpsResponseHandle_t respHandle,
                                                  char * pName,
                                                  uint32_t nameLen,
                                                  char * pValue,
                                                  uint32_t valueLen )
  {
      HTTPS_FUNCTION_ENTRY( IOT_HTTPS_OK );
  
      const char * pHttpParserErrorDescription = NULL;
      IotHttpsResponseBufferState_t savedBufferState = PROCESSING_STATE_NONE;
      IotHttpsResponseParserState_t savedParserState = PARSER_STATE_NONE;
      size_t numParsed = 0;
  
      HTTPS_ON_NULL_ARG_GOTO_CLEANUP( respHandle );
      HTTPS_ON_NULL_ARG_GOTO_CLEANUP( pName );
      HTTPS_ON_NULL_ARG_GOTO_CLEANUP( pValue );
      HTTPS_ON_ARG_ERROR_MSG_GOTO_CLEANUP( valueLen > 0,
                                           IOT_HTTPS_INVALID_PARAMETER,
                                           "pValue has insufficient space to store a value string (length is 0)" );
  
      /* The buffer processing state is changed to searching the header buffer in this function. The parser state is
      * changed in the response to wherever the parser is currently located in the response. If this function is called
      * in the middle of processing a response (for example in readReadyCallback() routine of an asynchronous response),
      * then parsing the response need to be able to start at the same place it was before calling this function. */
      savedBufferState = respHandle->bufferProcessingState;
      savedParserState = respHandle->parserState;
  
      /* The header search parameters in the response handle are used as context in the http-parser callbacks. During
       * the callback, pReadHeaderField is checked against the currently parsed header name. foundHeaderFiled is set to
       * true when the pReadHeaderField is found in a header field callback. The bufferProcessingState tells the callback
       * to skip the logic pertaining to when the response is being parsed for the first time. pReadHeaderValue will store
       * the header value found. readHeaderValueLength will store the the header value found's length from within the
       * response headers. */
      respHandle->pReadHeaderField = pName;
      respHandle->readHeaderFieldLength = nameLen;
      respHandle->foundHeaderField = false;
      respHandle->bufferProcessingState = PROCESSING_STATE_SEARCHING_HEADER_BUFFER;
      respHandle->pReadHeaderValue = NULL;
      respHandle->readHeaderValueLength = 0;
  
      /* Start over the HTTP parser so that it will parser from the beginning of the message. */
      http_parser_init( &( respHandle->httpParserInfo.readHeaderParser ), HTTP_RESPONSE );
  
      IotLogDebug( "Now parsing HTTP Message buffer to read a header." );
      numParsed = respHandle->httpParserInfo.parseFunc( &( respHandle->httpParserInfo.readHeaderParser ), &_httpParserSettings, ( char * ) ( respHandle->pHeaders ), respHandle->pHeadersCur - respHandle->pHeaders );
      IotLogDebug( "Parsed %d characters in IotHttpsClient_ReadHeader().", numParsed );
  
      /* There shouldn't be any errors parsing the response body given that the handle is from a validly
       * received response, so this check is defensive. If there were errors parsing the original response headers, then
       * the response handle would have been invalidated and the connection closed. */
      if( ( respHandle->httpParserInfo.readHeaderParser.http_errno != 0 ) &&
          ( HTTP_PARSER_ERRNO( &( respHandle->httpParserInfo.readHeaderParser ) ) > HPE_CB_chunk_complete ) )
      {
          pHttpParserErrorDescription = http_errno_description( HTTP_PARSER_ERRNO( &( respHandle->httpParserInfo.readHeaderParser ) ) );
          IotLogError( "http_parser failed on the http response with error: %s", pHttpParserErrorDescription );
          HTTPS_SET_AND_GOTO_CLEANUP( IOT_HTTPS_PARSING_ERROR );
      }
  
      /* Not only do we need an indication that the header field was found, but also that the value was found as well.
       * The value is found when it is non-NULL. The case where the header field is found, but the value is not found
       * occurs when there are incomplete headers stored in the header buffer. The header buffer could end with a header
       * field name. */
      if( respHandle->foundHeaderField && ( respHandle->pReadHeaderValue != NULL ) )
      {
          /* The len of the pValue buffer must account for the NULL terminator. */
          if( respHandle->readHeaderValueLength > ( valueLen - 1 ) )
          {
              IotLogError( "IotHttpsClient_ReadHeader(): The length of the pValue buffer specified is less than the actual length of the pValue. " );
              HTTPS_SET_AND_GOTO_CLEANUP( IOT_HTTPS_INSUFFICIENT_MEMORY );
          }
          else
          {
              memcpy( pValue, respHandle->pReadHeaderValue, respHandle->readHeaderValueLength );
              pValue[ respHandle->readHeaderValueLength ] = '\0';
          }
      }
      else
      {
          IotLogError( "IotHttpsClient_ReadHeader(): The header field %s was not found.", pName );
          HTTPS_SET_AND_GOTO_CLEANUP( IOT_HTTPS_NOT_FOUND );
      }
  
      HTTPS_FUNCTION_CLEANUP_BEGIN();
  
      /* Always restore the state back to what it was before entering this function. */
      if( respHandle != NULL )
      {
          respHandle->bufferProcessingState = savedBufferState;
          respHandle->parserState = savedParserState;
      }
  
      HTTPS_FUNCTION_CLEANUP_END();
  }
  
  /*-----------------------------------------------------------*/
  
  IotHttpsReturnCode_t IotHttpsClient_ReadContentLength( IotHttpsResponseHandle_t respHandle,
                                                         uint32_t * pContentLength )
  {
      HTTPS_FUNCTION_ENTRY( IOT_HTTPS_OK );
  
      const int CONTENT_LENGTH_NUMBERIC_BASE = 10;
      char pContentLengthStr[ HTTPS_MAX_CONTENT_LENGTH_LINE_LENGTH ] = { 0 };
  
      HTTPS_ON_NULL_ARG_GOTO_CLEANUP( respHandle );
      HTTPS_ON_NULL_ARG_GOTO_CLEANUP( pContentLength );
  
      /* If there is no content-length header or if we were not able to store it in the header buffer this will be
       * invalid. We do not use the content-length member of the http-parser state structure to get the content
       * length as this is a PRIVATE member. Because it is a PRIVATE member it can be any value. */
      status = IotHttpsClient_ReadHeader( respHandle, HTTPS_CONTENT_LENGTH_HEADER, FAST_MACRO_STRLEN( HTTPS_CONTENT_LENGTH_HEADER ), pContentLengthStr, HTTPS_MAX_CONTENT_LENGTH_LINE_LENGTH );
  
      if( HTTPS_FAILED( status ) )
      {
          *pContentLength = 0;
          IotLogError( "Could not read the Content-Length for the response." );
          HTTPS_GOTO_CLEANUP();
      }
  
      *pContentLength = strtoul( pContentLengthStr, NULL, CONTENT_LENGTH_NUMBERIC_BASE );
  
      HTTPS_FUNCTION_EXIT_NO_CLEANUP();
  }
  
  /*-----------------------------------------------------------*/
  
  /* Provide access to internal functions and variables if testing. */
  #if IOT_BUILD_TESTS == 1
      #include "iot_test_access_https_client.c"
  #endif
  