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417 lines
14 KiB
C
417 lines
14 KiB
C
/*
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* FreeRTOS+UDP V1.0.1 (C) 2013 Real Time Engineers ltd.
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* All rights reserved
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*
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* This file is part of the FreeRTOS+UDP distribution. The FreeRTOS+UDP license
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* terms are different to the FreeRTOS license terms.
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*
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* FreeRTOS+UDP uses a dual license model that allows the software to be used
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* under a standard GPL open source license, or a commercial license. The
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* standard GPL license (unlike the modified GPL license under which FreeRTOS
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* itself is distributed) requires that all software statically linked with
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* FreeRTOS+UDP is also distributed under the same GPL V2 license terms.
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* Details of both license options follow:
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*
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* - Open source licensing -
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* FreeRTOS+UDP is a free download and may be used, modified, evaluated and
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* distributed without charge provided the user adheres to version two of the
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* GNU General Public License (GPL) and does not remove the copyright notice or
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* this text. The GPL V2 text is available on the gnu.org web site, and on the
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* following URL: http://www.FreeRTOS.org/gpl-2.0.txt.
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*
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* - Commercial licensing -
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* Businesses and individuals that for commercial or other reasons cannot comply
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* with the terms of the GPL V2 license must obtain a commercial license before
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* incorporating FreeRTOS+UDP into proprietary software for distribution in any
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* form. Commercial licenses can be purchased from http://shop.freertos.org/udp
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* and do not require any source files to be changed.
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*
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* FreeRTOS+UDP is distributed in the hope that it will be useful. You cannot
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* use FreeRTOS+UDP unless you agree that you use the software 'as is'.
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* FreeRTOS+UDP is provided WITHOUT ANY WARRANTY; without even the implied
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* warranties of NON-INFRINGEMENT, MERCHANTABILITY or FITNESS FOR A PARTICULAR
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* PURPOSE. Real Time Engineers Ltd. disclaims all conditions and terms, be they
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* implied, expressed, or statutory.
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*
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* 1 tab == 4 spaces!
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*
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* http://www.FreeRTOS.org
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* http://www.FreeRTOS.org/udp
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*
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*/
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/* Standard includes. */
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#include <stdint.h>
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/* FreeRTOS includes. */
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#include "FreeRTOS.h"
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#include "task.h"
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#include "queue.h"
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#include "timers.h"
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/* FreeRTOS+UDP includes. */
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#include "FreeRTOS_UDP_IP.h"
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#include "FreeRTOS_IP_Private.h"
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#include "FreeRTOS_DNS.h"
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#include "FreeRTOS_Sockets.h"
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#include "NetworkInterface.h"
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#include "IPTraceMacroDefaults.h"
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/* Exclude the entire file if DNS is not enabled. */
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#if ipconfigUSE_DNS != 0
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#if( ipconfigBYTE_ORDER == FREERTOS_LITTLE_ENDIAN )
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#define dnsOUTGOING_FLAGS 0x0001 /* Standard query. */
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#define dnsTYPE 0x0100 /* A record (host address. */
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#define dnsCLASS 0x0100 /* IN */
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#define dnsDNS_PORT 0x3500
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#define dnsONE_QUESTION 0x0100
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#define dnsRX_FLAGS_MASK 0x0f80 /* The bits of interest in the flags field of incoming DNS messages. */
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#define dnsEXPECTED_RX_FLAGS 0x0080 /* Should be a response, without any errors. */
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#else
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#define dnsDNS_PORT 0x35
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#define dnsONE_QUESTION 0x01
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#define dnsFLAG_QUERY_RESPONSE_BIT 0x8000
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#define dnsFLAG_OPERATION_CODE_BITS 0x7800
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#define dnsFLAG_TRUNCATION_BIT 0x0200
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#define dnsFLAG_RESPONSE_CODE_BITS 0x000f
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#define dnsOUTGOING_FLAGS 0x0100 /* Standard query. */
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#define dnsTYPE 0x0001 /* A record (host address. */
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#define dnsCLASS 0x0001 /* IN */
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#define dnsRX_FLAGS_MASK 0x800f /* The bits of interest in the flags field of incoming DNS messages. */
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#define dnsEXPECTED_RX_FLAGS 0x8000 /* Should be a response, without any errors. */
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#endif /* ipconfigBYTE_ORDER */
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/* The maximum number of times a DNS request should be sent out if a response
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is not received, before giving up. */
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#define dnsMAX_REQUEST_ATTEMPTS 5
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/* If the top two bits in the first character of a name field are set then the
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name field is an offset to the string, rather than the string itself. */
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#define dnsNAME_IS_OFFSET ( ( uint8_t ) 0xc0 )
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/*
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* Create a socket and bind it to the standard DNS port number. Return the
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* the created socket - or NULL if the socket could not be created or bound.
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*/
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static xSocket_t prvCreateDNSSocket( void );
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/*
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* Create the DNS message in the zero copy buffer passed in the first parameter.
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*/
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static size_t prvCreateDNSMessage( uint8_t *pucUDPPayloadBuffer, const uint8_t *pcHostName, uint16_t usIdentifier );
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/*
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* Simple routine that jumps over the NAME field of a resource record.
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*/
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static uint8_t *prvSkipNameField( uint8_t *pucByte );
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/*
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* Process a response packet from a DNS server.
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*/
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static uint32_t prvParseDNSReply( uint8_t *pucUDPPayloadBuffer, uint16_t usIdentifier );
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/*-----------------------------------------------------------*/
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#include "pack_struct_start.h"
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struct xDNSMessage
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{
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uint16_t usIdentifier;
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uint16_t usFlags;
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uint16_t usQuestions;
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uint16_t usAnswers;
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uint16_t usAuthorityRRs;
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uint16_t usAdditionalRRs;
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}
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#include "pack_struct_end.h"
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typedef struct xDNSMessage xDNSMessage_t;
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/*-----------------------------------------------------------*/
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uint32_t FreeRTOS_gethostbyname( const uint8_t *pcHostName )
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{
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static uint16_t usIdentifier = 0;
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struct freertos_sockaddr xAddress;
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static xSocket_t xDNSSocket = NULL;
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uint32_t ulIPAddress = 0UL;
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uint8_t *pucUDPPayloadBuffer;
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static uint32_t ulAddressLength;
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portBASE_TYPE xAttempt;
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int32_t lBytes;
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size_t xPayloadLength;
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const size_t xExpectedPayloadLength = sizeof( xDNSMessage_t ) + strlen( ( const char * const ) pcHostName ) + sizeof( uint16_t ) + sizeof( uint16_t ) + 2; /* Two for the count of characters in the first subdomain part, and the string end byte */
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if( xDNSSocket == NULL )
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{
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xDNSSocket = prvCreateDNSSocket();
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}
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if( xDNSSocket != NULL )
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{
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/* Generate a unique identifier for this query. */
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usIdentifier++;
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for( xAttempt = 0; xAttempt < dnsMAX_REQUEST_ATTEMPTS; xAttempt++ )
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{
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/* Get a buffer. This uses a maximum delay, but the delay will be
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capped to ipconfigMAX_SEND_BLOCK_TIME_TICKS so the return value
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still needs to be tested. */
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pucUDPPayloadBuffer = ( uint8_t * ) FreeRTOS_GetUDPPayloadBuffer( xExpectedPayloadLength, portMAX_DELAY );
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if( pucUDPPayloadBuffer != NULL )
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{
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/* Create the message in the obtained buffer. */
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xPayloadLength = prvCreateDNSMessage( pucUDPPayloadBuffer, pcHostName, usIdentifier );
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iptraceSENDING_DNS_REQUEST();
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/* Obtain the DNS server address. */
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FreeRTOS_GetAddressConfiguration( NULL, NULL, NULL, &ulIPAddress );
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/* Send the DNS message. */
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xAddress.sin_addr = ulIPAddress;
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xAddress.sin_port = dnsDNS_PORT;
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ulIPAddress = 0;
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if( FreeRTOS_sendto( xDNSSocket, pucUDPPayloadBuffer, xPayloadLength, FREERTOS_ZERO_COPY, &xAddress, sizeof( xAddress ) ) != 0 )
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{
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/* Wait for the reply. */
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lBytes = FreeRTOS_recvfrom( xDNSSocket, &pucUDPPayloadBuffer, 0, FREERTOS_ZERO_COPY, &xAddress, &ulAddressLength );
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if( lBytes > 0 )
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{
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/* The reply was received. Process it. */
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ulIPAddress = prvParseDNSReply( pucUDPPayloadBuffer, usIdentifier );
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/* Finished with the buffer. The zero copy interface
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is being used, so the buffer must be freed by the
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task. */
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FreeRTOS_ReleaseUDPPayloadBuffer( ( void * ) pucUDPPayloadBuffer );
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if( ulIPAddress != 0 )
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{
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/* All done. */
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break;
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}
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}
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}
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else
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{
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/* The message was not sent so the stack will not be
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releasing the zero copy - it must be released here. */
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FreeRTOS_ReleaseUDPPayloadBuffer( ( void * ) pucUDPPayloadBuffer );
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}
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}
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}
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}
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return ulIPAddress;
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}
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/*-----------------------------------------------------------*/
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static size_t prvCreateDNSMessage( uint8_t *pucUDPPayloadBuffer, const uint8_t *pcHostName, uint16_t usIdentifier )
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{
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xDNSMessage_t *pxDNSMessageHeader;
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uint8_t *pucStart, *pucByte;
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const uint16_t usARecordType = dnsTYPE, usClass = dnsCLASS;
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static const xDNSMessage_t xDefaultPartDNSHeader =
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{
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0, /* The identifier will be overwritten. */
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dnsOUTGOING_FLAGS, /* Flags set for standard query. */
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dnsONE_QUESTION, /* One question is being asked. */
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0, /* No replies are included. */
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0, /* No authorities. */
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0 /* No additional authorities. */
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};
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/* Copy in the const part of the header. */
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memcpy( ( void * ) pucUDPPayloadBuffer, ( void * ) &xDefaultPartDNSHeader, sizeof( xDefaultPartDNSHeader ) );
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/* Write in a unique identifier. */
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pxDNSMessageHeader = ( xDNSMessage_t * ) pucUDPPayloadBuffer;
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pxDNSMessageHeader->usIdentifier = usIdentifier;
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/* Create the resource record at the end of the header. First
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find the end of the header. */
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pucStart = pucUDPPayloadBuffer + sizeof( xDefaultPartDNSHeader );
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/* Leave a gap for the first length bytes. */
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pucByte = pucStart + 1;
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/* Copy in the host name. */
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strcpy( ( char * ) pucByte, ( const char * ) pcHostName );
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/* Mark the end of the string. */
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pucByte += strlen( ( const char * ) pcHostName );
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*pucByte = 0x00;
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/* Walk the string to replace the '.' characters with byte counts.
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pucStart holds the address of the byte count. Walking the string
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starts after the byte count position. */
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pucByte = pucStart;
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do
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{
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pucByte++;
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while( ( *pucByte != 0x00 ) && ( *pucByte != '.' ) )
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{
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pucByte++;
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}
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/* Fill in the byte count, then move the pucStart pointer up to
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the found byte position. */
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*pucStart = ( uint8_t ) ( ( uint32_t ) pucByte - ( uint32_t ) pucStart );
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( *pucStart )--;
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pucStart = pucByte;
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} while( *pucByte != 0x00 );
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/* Finish off the record. */
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pucByte++;
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memcpy( ( void * ) pucByte, &usARecordType, sizeof( uint16_t ) );
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pucByte += sizeof( uint16_t );
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memcpy( ( void * ) pucByte, &usClass, sizeof( uint16_t ) );
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pucByte += sizeof( uint16_t );
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/* Return the total size of the generated message, which is the space from
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the last written byte to the beginning of the buffer. */
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return ( ( uint32_t ) pucByte - ( uint32_t ) pucUDPPayloadBuffer );
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}
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/*-----------------------------------------------------------*/
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static uint8_t *prvSkipNameField( uint8_t *pucByte )
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{
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/* Determine if the name is the fully coded name, or an offset to the name
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elsewhere in the message. */
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if( ( *pucByte & dnsNAME_IS_OFFSET ) == dnsNAME_IS_OFFSET )
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{
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/* Jump over the two byte offset. */
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pucByte += sizeof( uint16_t );
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}
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else
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{
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/* pucByte points to the full name. Walk over the string. */
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while( *pucByte != 0x00 )
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{
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/* The number of bytes to jump for each name section is stored in the byte
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before the name section. */
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pucByte += ( *pucByte + 1 );
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}
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pucByte++;
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}
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return pucByte;
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}
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/*-----------------------------------------------------------*/
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static uint32_t prvParseDNSReply( uint8_t *pucUDPPayloadBuffer, uint16_t usIdentifier )
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{
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xDNSMessage_t *pxDNSMessageHeader;
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uint32_t ulIPAddress = 0UL;
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uint8_t *pucByte;
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uint16_t x, usDataLength;
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const uint16_t usARecordType = dnsTYPE;
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pxDNSMessageHeader = ( xDNSMessage_t * ) pucUDPPayloadBuffer;
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if( pxDNSMessageHeader->usIdentifier == usIdentifier )
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{
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if( ( pxDNSMessageHeader->usFlags & dnsRX_FLAGS_MASK ) == dnsEXPECTED_RX_FLAGS )
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{
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/* Start at the first byte after the header. */
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pucByte = pucUDPPayloadBuffer + sizeof( xDNSMessage_t );
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/* Skip any question records. */
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pxDNSMessageHeader->usQuestions = FreeRTOS_ntohs( pxDNSMessageHeader->usQuestions );
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for( x = 0; x < pxDNSMessageHeader->usQuestions; x++ )
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{
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/* Skip the variable length name field. */
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pucByte = prvSkipNameField( pucByte );
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/* Skip the type and class fields. */
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pucByte += sizeof( uint32_t );
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}
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/* Search through the answers records. */
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pxDNSMessageHeader->usAnswers = FreeRTOS_ntohs( pxDNSMessageHeader->usAnswers );
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for( x = 0; x < pxDNSMessageHeader->usAnswers; x++ )
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{
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pucByte = prvSkipNameField( pucByte );
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/* Is the type field that of an A record? */
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if( memcmp( ( void * ) pucByte, ( void * ) &usARecordType, sizeof( uint16_t ) ) == 0 )
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{
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/* This is the required record. Skip the type, class, and
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time to live fields, plus the first byte of the data
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length. */
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pucByte += ( sizeof( uint32_t ) + sizeof( uint32_t ) + sizeof( uint8_t ) );
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/* Sanity check the data length. */
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if( *pucByte == sizeof( uint32_t ) )
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{
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/* Skip the second byte of the length. */
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pucByte++;
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/* Copy the IP address out of the record. */
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memcpy( ( void * ) &ulIPAddress, ( void * ) pucByte, sizeof( uint32_t ) );
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}
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break;
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}
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else
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{
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/* Skip the type, class and time to live fields. */
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pucByte += ( sizeof( uint32_t ) + sizeof( uint32_t ) );
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/* Determine the length of the data in the field. */
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memcpy( ( void * ) &usDataLength, ( void * ) pucByte, sizeof( uint16_t ) );
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usDataLength = FreeRTOS_ntohs( usDataLength );
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/* Jump over the data lenth bytes, and the data itself. */
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pucByte += usDataLength + sizeof( uint16_t );
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}
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}
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}
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}
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return ulIPAddress;
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}
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/*-----------------------------------------------------------*/
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static xSocket_t prvCreateDNSSocket( void )
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{
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static xSocket_t xSocket = NULL;
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struct freertos_sockaddr xAddress;
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portBASE_TYPE xReturn;
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portTickType xTimeoutTime = 200 / portTICK_RATE_MS;
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/* This must be the first time this function has been called. Create
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the socket. */
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xSocket = FreeRTOS_socket( FREERTOS_AF_INET, FREERTOS_SOCK_DGRAM, FREERTOS_IPPROTO_UDP );
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/* Auto bind the port. */
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xAddress.sin_port = 0;
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xReturn = FreeRTOS_bind( xSocket, &xAddress, sizeof( xAddress ) );
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/* Check the bind was successful, and clean up if not. */
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if( xReturn != 0 )
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{
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FreeRTOS_closesocket( xSocket );
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xSocket = NULL;
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}
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else
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{
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/* Set the send and receive timeouts. */
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FreeRTOS_setsockopt( xSocket, 0, FREERTOS_SO_RCVTIMEO, ( void * ) &xTimeoutTime, sizeof( portTickType ) );
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FreeRTOS_setsockopt( xSocket, 0, FREERTOS_SO_SNDTIMEO, ( void * ) &xTimeoutTime, sizeof( portTickType ) );
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}
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return xSocket;
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}
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#endif /* ipconfigUSE_DNS != 0 */
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