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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 ip
  30.  *  @{
  31.  */
  32.  
  33. /** @file
  34.  *  IP header and options definitions.
  35.  *  Based on the RFC~791.
  36.  */
  37.  
  38. #ifndef __NET_IP_HEADER_H__
  39. #define __NET_IP_HEADER_H__
  40.  
  41. #include <byteorder.h>
  42. #include <sys/types.h>
  43.  
  44. /** Returns the actual IP header length.
  45.  *  @param header The IP packet header. Input parameter.
  46.  */
  47. #define IP_HEADER_LENGTH( header )      (( header )->header_length * 4u )
  48.  
  49. /** Returns the actual IP header length.
  50.  *  @param header The IP packet header. Input parameter.
  51.  */
  52. #define IP_COMPUTE_HEADER_LENGTH( length )      (( uint8_t ) (( length ) / 4u ))
  53.  
  54. /** Returns the actual IP packet total length.
  55.  *  @param header The IP packet header. Input parameter.
  56.  */
  57. #define IP_TOTAL_LENGTH( header )       ntohs(( header )->total_length )
  58.  
  59. /** Returns the actual IP packet data length.
  60.  *  @param header The IP packet header. Input parameter.
  61.  */
  62. #define IP_HEADER_DATA_LENGTH( header ) ( IP_TOTAL_LENGTH( header ) - IP_HEADER_LENGTH( header ))
  63.  
  64. /** Returns the IP packet header checksum.
  65.  *  @param header The IP packet header. Input parameter.
  66.  */
  67. #define IP_HEADER_CHECKSUM( header )    ( htons( ip_checksum(( uint8_t * )( header ), IP_HEADER_LENGTH( header ))))
  68.  
  69. /** Returns the fragment offest.
  70.  *  @param header The IP packet header. Input parameter.
  71.  */
  72. #define IP_FRAGMENT_OFFSET( header ) (((( header )->fragment_offset_high << 8 ) + ( header )->fragment_offset_low ) * 8u )
  73.  
  74. /** Returns the fragment offest high bits.
  75.  *  @param length The prefixed data total length. Input parameter.
  76.  */
  77. #define IP_COMPUTE_FRAGMENT_OFFSET_HIGH( length ) (((( length ) / 8u ) & 0x1F00 ) >> 8 )
  78.  
  79. /** Returns the fragment offest low bits.
  80.  *  @param length The prefixed data total length. Input parameter.
  81.  */
  82. #define IP_COMPUTE_FRAGMENT_OFFSET_LOW( length ) ((( length ) / 8u ) & 0xFF )
  83.  
  84. /** Type definition of the internet header.
  85.  *  @see ip_header
  86.  */
  87. typedef struct ip_header    ip_header_t;
  88.  
  89. /** Type definition of the internet header pointer.
  90.  *  @see ip_header
  91.  */
  92. typedef ip_header_t *       ip_header_ref;
  93.  
  94. /** Internet header.
  95.  *  The variable options should be included after the header itself and indicated by the increased header length value.
  96.  */
  97. struct ip_header{
  98. #ifdef ARCH_IS_BIG_ENDIAN
  99.     /** The Version field indicates the format of the internet header.
  100.      */
  101.     uint8_t     version:4;
  102.     /** Internet Header Length is the length of the internet header in 32~bit words, and thus points to the beginning of the data.
  103.      *  Note that the minimum value for a~correct header is~5.
  104.      */
  105.     uint8_t     header_length:4;
  106. #else
  107.     /** Internet Header Length is the length of the internet header in 32~bit words, and thus points to the beginning of the data.
  108.      *  Note that the minimum value for a~correct header is~5.
  109.      */
  110.     uint8_t     header_length:4;
  111.     /** The Version field indicates the format of the internet header.
  112.      */
  113.     uint8_t     version:4;
  114. #endif
  115.     /** The Type of Service provides an indication of the abstract parameters of the quality of service desired.
  116.      *  These parameters are to be used to guide the selection of the actual service parameters when transmitting a~datagram through a~particular network.
  117.      *  Several networks offer service precedence, which somehow treats high precedence traffic as more important than other traffic (generally by accepting only traffic above a~certain precedence at time of high load).
  118.      *  The major choice is a~three way tradeoff between low-delay, high-reliability, and high-throughput.
  119.      */
  120.     uint8_t     tos;
  121.     /** Total Length is the length of the datagram, measured in octets, including internet header and data.
  122.      *  This field allows the length of a~datagram to be up to 65,535~octets.
  123.      */
  124.     uint16_t    total_length;
  125.     /** An identifying value assigned by the sender to aid in assembling the fragments of a~datagram.
  126.      */
  127.     uint16_t    identification;
  128. #ifdef ARCH_IS_BIG_ENDIAN
  129.     /** Various control flags.
  130.      */
  131.     uint8_t flags:3;
  132.     /** This field indicates where in the datagram this fragment belongs.
  133.      *  High bits.
  134.      */
  135.     uint8_t fragment_offset_high:5;
  136. #else
  137.     /** This field indicates where in the datagram this fragment belongs.
  138.      *  High bits.
  139.      */
  140.     uint8_t fragment_offset_high:5;
  141.     /** Various control flags.
  142.      */
  143.     uint8_t flags:3;
  144. #endif
  145.     /** This field indicates where in the datagram this fragment belongs.
  146.      *  Low bits.
  147.      */
  148.     uint8_t fragment_offset_low;
  149.     /** This field indicates the maximum time the datagram is allowed to remain in the internet system.
  150.      *  If this field contains the value zero, then the datagram must be destroyed.
  151.      *  This field is modified in internet header processing.
  152.      *  The time is measured in units of seconds, but since every module that processes a~datagram must decrease the TTL by at least one even if it process the datagram in less than a~second, the TTL must be thought of only as an upper bound on the time a~datagram may exist.
  153.      *  The intention is to cause undeliverable datagrams to be discarded, and to bound the maximum datagram lifetime.
  154.      */
  155.     uint8_t     ttl;
  156.     /** This field indicates the next level protocol used in the data portion of the internet datagram.
  157.      */
  158.     uint8_t     protocol;
  159.     /** A checksum of the header only.
  160.      *  Since some header fields change (e.g., time to live), this is recomputed and verified at each point that the internet header is processed.
  161.      *  The checksum algorithm is: The checksum field is the 16~bit one's complement of the one's complement sum of all 16~bit words in the header.
  162.      *  For purposes of computing the checksum, the value of the checksum field is zero.
  163.      */
  164.     uint16_t    header_checksum;
  165.     /** The source address.
  166.      */
  167.     uint32_t    source_address;
  168.     /** The destination address.
  169.      */
  170.     uint32_t    destination_address;
  171. } __attribute__ ((packed));
  172.  
  173. /** Type definition of the internet option header.
  174.  *  @see ip_header
  175.  */
  176. typedef struct ip_option    ip_option_t;
  177.  
  178. /** Type definition of the internet option header pointer.
  179.  *  @see ip_header
  180.  */
  181. typedef ip_option_t *       ip_option_ref;
  182.  
  183. /** Internet option header.
  184.  *  Only type field is always valid.
  185.  *  Other fields' validity depends on the option type.
  186.  */
  187. struct ip_option{
  188.     /** A single octet of option-type.
  189.      */
  190.     uint8_t     type;
  191.     /** An option length octet.
  192.      */
  193.     uint8_t     length;
  194.     /** A~pointer.
  195.      */
  196.     uint8_t     pointer;
  197. #ifdef ARCH_IS_BIG_ENDIAN
  198.     /** The number of IP modules that cannot register timestamps due to lack of space.
  199.      */
  200.     uint8_t overflow:4;
  201.     /** Various internet timestamp control flags.
  202.      */
  203.     uint8_t flags:4;
  204. #else
  205.     /** Various internet timestamp control flags.
  206.      */
  207.     uint8_t flags:4;
  208.     /** The number of IP modules that cannot register timestamps due to lack of space.
  209.      */
  210.     uint8_t overflow:4;
  211. #endif
  212. } __attribute__ ((packed));
  213.  
  214. /** @name IP flags definitions
  215.  */
  216. /*@{*/
  217.  
  218. /** Fragment flag field shift.
  219.  */
  220. #define IPFLAG_FRAGMENT_SHIFT       1
  221.  
  222. /** Fragmented flag field shift.
  223.  */
  224. #define IPFLAG_FRAGMENTED_SHIFT     0
  225.  
  226. /** May fragment flag value.
  227.  *  Allows the packet fragmentation.
  228.  */
  229. #define IPFLAG_MAY_FRAGMENT         ( 0x0 << IPFLAG_FRAGMENT_SHIFT )
  230.  
  231. /** Don't fragment flag value.
  232.  *  Permits the packet fragmentation.
  233.  */
  234. #define IPFLAG_DONT_FRAGMENT        ( 0x1 << IPFLAG_FRAGMENT_SHIFT )
  235.  
  236. /** Last fragment flag value.
  237.  *  Indicates the last packet fragment.
  238.  */
  239. #define IPFLAG_LAST_FRAGMENT        ( 0x0 << IPFLAG_FRAGMENTED_SHIFT )
  240.  
  241. /** More fragments flag value.
  242.  *  Indicates that more packet fragments follow.
  243.  */
  244. #define IPFLAG_MORE_FRAGMENTS       ( 0x1 << IPFLAG_FRAGMENTED_SHIFT )
  245.  
  246. /*@}*/
  247.  
  248. /** Type definition of the internet version 4 pseudo header.
  249.  *  @see ipv4_pseudo_header
  250.  */
  251. typedef struct ipv4_pseudo_header   ipv4_pseudo_header_t;
  252.  
  253. /** Type definition of the internet version 4 pseudo header pointer.
  254.  *  @see ipv4_pseudo_header
  255.  */
  256. typedef ipv4_pseudo_header_t *      ipv4_pseudo_header_ref;
  257.  
  258. /** Internet version 4 pseudo header.
  259.  */
  260. struct ipv4_pseudo_header{
  261.     /** The source address.
  262.      */
  263.     uint32_t    source_address;
  264.     /** The destination address.
  265.      */
  266.     uint32_t    destination_address;
  267.     /** Reserved byte.
  268.      *  Must be zero.
  269.      */
  270.     uint8_t     reserved;
  271.     /** This field indicates the next level protocol used in the data portion of the internet datagram.
  272.      */
  273.     uint8_t     protocol;
  274.     /** Data length is the length of the datagram, measured in octets.
  275.      */
  276.     uint16_t    data_length;
  277. } __attribute__ ((packed));
  278.  
  279. #endif
  280.  
  281. /** @}
  282.  */
  283.