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  1. /*
  2.  * Copyright (c) 2009 Lukas Mejdrech
  3.  * All rights reserved.
  4.  *
  5.  * Redistribution and use in source and binary forms, with or without
  6.  * modification, are permitted provided that the following conditions
  7.  * are met:
  8.  *
  9.  * - Redistributions of source code must retain the above copyright
  10.  *   notice, this list of conditions and the following disclaimer.
  11.  * - Redistributions in binary form must reproduce the above copyright
  12.  *   notice, this list of conditions and the following disclaimer in the
  13.  *   documentation and/or other materials provided with the distribution.
  14.  * - The name of the author may not be used to endorse or promote products
  15.  *   derived from this software without specific prior written permission.
  16.  *
  17.  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  18.  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  19.  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  20.  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  21.  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  22.  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23.  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24.  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25.  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  26.  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27.  */
  28.  
  29. /** @addtogroup tcp
  30.  *  @{
  31.  */
  32.  
  33. /** @file
  34.  *  TCP header definition.
  35.  *  Based on the RFC~793.
  36.  */
  37.  
  38. #ifndef __NET_TCP_HEADER_H__
  39. #define __NET_TCP_HEADER_H__
  40.  
  41. #include <sys/types.h>
  42.  
  43. /** Returns the actual TCP header length.
  44.  *  @param header The TCP packet header. Input parameter.
  45.  */
  46. #define TCP_HEADER_LENGTH( header )     (( header )->header_length * 4u )
  47.  
  48. /** Returns the actual TCP header length.
  49.  *  @param header The TCP packet header. Input parameter.
  50.  */
  51. #define TCP_COMPUTE_HEADER_LENGTH( length )     (( uint8_t ) (( length ) / 4u ))
  52.  
  53. /** Type definition of the transmission datagram header.
  54.  *  @see tcp_header
  55.  */
  56. typedef struct tcp_header   tcp_header_t;
  57.  
  58. /** Type definition of the transmission datagram header pointer.
  59.  *  @see tcp_header
  60.  */
  61. typedef tcp_header_t *      tcp_header_ref;
  62.  
  63. /** Type definition of the transmission datagram header option.
  64.  *  @see tcp_option
  65.  */
  66. typedef struct tcp_option   tcp_option_t;
  67.  
  68. /** Type definition of the transmission datagram header option pointer.
  69.  *  @see tcp_option
  70.  */
  71. typedef tcp_option_t *      tcp_option_ref;
  72.  
  73. /** Type definition of the Maximum segment size TCP option.
  74.  *  @see ...
  75.  */
  76. typedef struct tcp_max_segment_size_option  tcp_max_segment_size_option_t;
  77.  
  78. /** Type definition of the Maximum segment size TCP option pointer.
  79.  *  @see tcp_max_segment_size_option
  80.  */
  81. typedef tcp_max_segment_size_option_t *     tcp_max_segment_size_option_ref;
  82.  
  83. /** Transmission datagram header.
  84.  */
  85. struct tcp_header{
  86.     /** The source port number.
  87.      */
  88.     uint16_t    source_port;
  89.     /** The destination port number.
  90.      */
  91.     uint16_t    destination_port;
  92.     /** The sequence number of the first data octet in this segment (except when SYN is present).
  93.      *  If SYN is present the sequence number is the initial sequence number (ISN) and the first data octet is ISN+1.
  94.      */
  95.     uint32_t    sequence_number;
  96.     /** If the ACK control bit is set this field contains the value of the next sequence number the sender of the segment is expecting to receive.
  97.      *  Once a~connection is established this is always sent.
  98.      *  @see acknowledge
  99.      */
  100.     uint32_t    acknowledgement_number;
  101. #ifdef ARCH_IS_BIG_ENDIAN
  102.     /** The number of 32~bit words in the TCP Header.
  103.      *  This indicates where the data begins.
  104.      *  The TCP header (even one including options) is an integral number of 32~bits long.
  105.      */
  106.     uint8_t header_length:4;
  107.     /** Four bits reserved for future use.
  108.      *  Must be zero.
  109.      */
  110.     uint8_t reserved1:4;
  111. #else
  112.     /** Four bits reserved for future use.
  113.      *  Must be zero.
  114.      */
  115.     uint8_t reserved1:4;
  116.     /** The number of 32~bit words in the TCP Header.
  117.      *  This indicates where the data begins.
  118.      *  The TCP header (even one including options) is an integral number of 32~bits long.
  119.      */
  120.     uint8_t header_length:4;
  121. #endif
  122. #ifdef ARCH_IS_BIG_ENDIAN
  123.     /** Two bits reserved for future use.
  124.      *  Must be zero.
  125.      */
  126.     uint8_t reserved2:2;
  127.     /** Urgent Pointer field significant.
  128.      *  @see tcp_header:urgent_pointer
  129.      */
  130.     uint8_t urgent:1;
  131.     /** Acknowledgment field significant
  132.      *  @see tcp_header:acknowledgement_number
  133.      */
  134.     uint8_t acknowledge:1;
  135.     /** Push function.
  136.      */
  137.     uint8_t push:1;
  138.     /** Reset the connection.
  139.      */
  140.     uint8_t reset:1;
  141.     /** Synchronize the sequence numbers.
  142.      */
  143.     uint8_t synchronize:1;
  144.     /** No more data from the sender.
  145.      */
  146.     uint8_t finalize:1;
  147. #else
  148.     /** No more data from the sender.
  149.      */
  150.     uint8_t finalize:1;
  151.     /** Synchronize the sequence numbers.
  152.      */
  153.     uint8_t synchronize:1;
  154.     /** Reset the connection.
  155.      */
  156.     uint8_t reset:1;
  157.     /** Push function.
  158.      */
  159.     uint8_t push:1;
  160.     /** Acknowledgment field significant.
  161.      *  @see tcp_header:acknowledgement_number
  162.      */
  163.     uint8_t acknowledge:1;
  164.     /** Urgent Pointer field significant.
  165.      *  @see tcp_header:urgent_pointer
  166.      */
  167.     uint8_t urgent:1;
  168.     /** Two bits reserved for future use.
  169.      *  Must be zero.
  170.      */
  171.     uint8_t reserved2:2;
  172. #endif
  173.     /** The number of data octets beginning with the one indicated in the acknowledgment field which the sender of this segment is willing to accept.
  174.      *  @see tcp_header:acknowledge
  175.      */
  176.     uint16_t    window;
  177.     /** The checksum field is the 16~bit one's complement of the one's complement sum of all 16~bit words in the header and text.
  178.      *  If a~segment contains an odd number of header and text octets to be checksummed, the last octet is padded on the right with zeros to form a~16~bit word for checksum purposes.
  179.      *  The pad is not transmitted as part of the segment.
  180.      *  While computing the checksum, the checksum field itself is replaced with zeros.
  181.      *  The checksum also coves a~pseudo header conceptually.
  182.      *  The pseudo header conceptually prefixed to the TCP header contains the source address, the destination address, the protocol, and the TCP length.
  183.      *  This information gives protection against misrouted datagrams.
  184.      *  If the computed checksum is zero, it is transmitted as all ones (the equivalent in one's complement arithmetic).
  185.      */
  186.     uint16_t    checksum;
  187.     /** This field communicates the current value of the urgent pointer as a~positive offset from the sequence number in this segment.
  188.      *  The urgent pointer points to the sequence number of the octet following the urgent data.
  189.      *  This field is only be interpreted in segments with the URG control bit set.
  190.      *  @see tcp_header:urgent
  191.      */
  192.     uint16_t    urgent_pointer;
  193. } __attribute__ ((packed));
  194.  
  195. /** Transmission datagram header option.
  196.  */
  197. struct tcp_option{
  198.     /** Option type.
  199.      */
  200.     uint8_t     type;
  201.     /** Option length.
  202.      */
  203.     uint8_t     length;
  204. };
  205.  
  206. /** Maximum segment size TCP option.
  207.  */
  208. struct tcp_max_segment_size_option{
  209.     /** TCP option.
  210.      *  @see TCPOPT_MAX_SEGMENT_SIZE
  211.      *  @see TCPOPT_MAX_SEGMENT_SIZE_LENGTH
  212.      */
  213.     tcp_option_t    option;
  214.     /** Maximum segment size in bytes.
  215.      */
  216.     uint16_t        max_segment_size;
  217. } __attribute__ ((packed));
  218.  
  219. #endif
  220.  
  221. /** @}
  222.  */
  223.