sr_protocol.h

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/*
 *  Copyright (c) 1998, 1999, 2000 Mike D. Schiffman <mike@infonexus.com>
 *  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 */

/** \file
 * A collection of macros, structs, and enums to represent packet types and
 * headers.
 */

#ifndef SR_PROTOCOL_H
#define SR_PROTOCOL_H

#ifdef _LINUX_
#include <stdint.h>
#endif /* _LINUX_ */

#include <sys/types.h>
#include <arpa/inet.h>


#ifndef IP_MAXPACKET
#define IP_MAXPACKET 65535
#endif


#ifndef __LITTLE_ENDIAN
#define __LITTLE_ENDIAN 1
#endif

#ifndef __BIG_ENDIAN
#define __BIG_ENDIAN 2
#endif

#ifndef __BYTE_ORDER
  #ifdef _CYGWIN_
  #define __BYTE_ORDER __LITTLE_ENDIAN
  #endif
  #ifdef _LINUX_
  #define __BYTE_ORDER __LITTLE_ENDIAN
  #endif
  #ifdef _SOLARIS_
  #define __BYTE_ORDER __BIG_ENDIAN
  #endif
  #ifdef _DARWIN_
  #define __BYTE_ORDER __BIG_ENDIAN
  #endif
#endif
#define ICMP_DATA_SIZE 28
#define ICMP_ZERO_HEADER_SIZE 10
#define ICMP_ELEVEN_HEADER_SIZE 36


/** General struct of a ICMP header. 
 * See <a href="https://en.wikipedia.org/wiki/Internet_Control_Message_Protocol">here</a> for more details.
 */
struct sr_icmp_hdr {
  uint8_t icmp_type; /**< icmp type*/
  uint8_t icmp_code; /**< icmp code, if needed*/
  uint16_t icmp_sum; /**< icmp checksum*/
  uint16_t icmp_id; /**< icmp identifier, you shouldn't need to use this*/
  uint16_t icmp_seq; /**< icmp sequence number, you shouldn't need to use this*/

} __attribute__ ((packed)) ;
typedef struct sr_icmp_hdr sr_icmp_hdr_t;

/** Struct of a Type-0 (echo reply) ICMP header. 
 * See <a href="https://en.wikipedia.org/wiki/Internet_Control_Message_Protocol">here</a> for more details.
 */
struct sr_icmp_t0_hdr{
  uint8_t icmp_type;
  uint8_t icmp_code;
  uint16_t icmp_sum;
  uint16_t icmp_id;
  uint16_t icmp_seq;
  uint16_t timestamp;
  uint16_t data[ICMP_DATA_SIZE/2];
} __attribute__ ((packed)) ;
typedef struct sr_icmp_t0_hdr sr_icmp_t0_hdr_t;

/** Struct of a Type-3 (destination unreachable) ICMP header. 
 * See <a href="https://en.wikipedia.org/wiki/Internet_Control_Message_Protocol">here</a> for more details.
 */
struct sr_icmp_t3_hdr {
  uint8_t icmp_type;
  uint8_t icmp_code;
  uint16_t icmp_sum;
  uint16_t unused;
  uint16_t next_mtu;
  uint8_t data[ICMP_DATA_SIZE];

} __attribute__ ((packed)) ;
typedef struct sr_icmp_t3_hdr sr_icmp_t3_hdr_t;

/** Struct of a Type-11 (TTL exceeded) ICMP header. 
 * See <a href="https://en.wikipedia.org/wiki/Internet_Control_Message_Protocol">here</a> for more details.
 */
struct sr_icmp_t11_hdr {
  uint8_t icmp_type;
  uint8_t icmp_code;
  uint16_t icmp_sum;
  uint32_t unused;
  uint32_t data[ICMP_DATA_SIZE/4];
} __attribute__ ((packed)) ;
typedef struct sr_icmp_t11_hdr sr_icmp_t11_hdr_t;


/** Struct of an IP header, without options
 */
struct sr_ip_hdr
  {
#if __BYTE_ORDER == __LITTLE_ENDIAN
    unsigned int ip_hl:4;       /**< header length*/
    unsigned int ip_v:4;        /**< version (always IPv4) */
#elif __BYTE_ORDER == __BIG_ENDIAN
    unsigned int ip_v:4;        /**< version (always IPv4) */
    unsigned int ip_hl:4;       /**< header length*/
#else
#error "Byte ordering not specified "
#endif
    uint8_t ip_tos;         /**< type of service */
    uint16_t ip_len;            /**< total length */
    uint16_t ip_id;         /**< identification */
    uint16_t ip_off;            /**< fragment offset field */
#define IP_RF 0x8000            /**< reserved fragment flag */
#define IP_DF 0x4000            /**< dont fragment flag */
#define IP_MF 0x2000            /**< more fragments flag */
#define IP_OFFMASK 0x1fff       /**< mask for fragmenting bits */
    uint8_t ip_ttl;         /**< time to live */
    uint8_t ip_p;           /**< protocol of encapsulated packet*/
    uint16_t ip_sum;            /**< IP checksum */
    uint32_t ip_src;    /**< src IP address */
    uint32_t ip_dst;    /**< dest IP address */
  } __attribute__ ((packed)) ;
typedef struct sr_ip_hdr sr_ip_hdr_t;

/** Struct of an Ethernet Header
 */
struct sr_ethernet_hdr
{
#ifndef ETHER_ADDR_LEN
#define ETHER_ADDR_LEN 6
#endif
    uint8_t  ether_dhost[ETHER_ADDR_LEN];    /**< destination ethernet address */
    uint8_t  ether_shost[ETHER_ADDR_LEN];    /**< source ethernet address */
    uint16_t ether_type;                     /**< type (protocol) of encapsulated packet */
} __attribute__ ((packed)) ;
typedef struct sr_ethernet_hdr sr_ethernet_hdr_t;

/* Types */
#define ICMP_TYPE_ECHO_REPLY    0
#define ICMP_TYPE_DEST_UNREACH  3
#define ICMP_TYPE_ECHO_REQUEST  8
#define ICMP_TYPE_TIME_EXCEEDED 11

/* Codes */
#define ICMP_CODE_NET_UNREACH   0
#define ICMP_CODE_HOST_UNREACH  1
#define ICMP_CODE_PROTO_UNREACH 2
#define ICMP_CODE_PORT_UNREACH  3
#define ICMP_CODE_TTL_EXPIRED   0

/* IP constants */
#define IP_PROTO_ICMP 0x0001
#define IPV4_HEADER_LEN 20
#define ICMP_HEADER_LEN 8

/** Enumeration of useful codes for protocols encapsulated in IP */
enum sr_ip_protocol {
  ip_protocol_icmp = 0x0001,
};

/** Enumeration of useful codes for protocols encapsulated in Ethernet */
enum sr_ethertype {
  ethertype_arp = 0x0806,
  ethertype_ip = 0x0800,
};

/** Enumeration of useful codes for ARP operations */
enum sr_arp_opcode {
  arp_op_request = 0x0001,
  arp_op_reply = 0x0002,
};

/** Enumeration of useful hardware format codes for ARP */
enum sr_arp_hrd_fmt {
  arp_hrd_ethernet = 0x0001,
};

/** Struct of an ARP header */
struct sr_arp_hdr
{
    unsigned short  ar_hrd;             /**< format of hardware address   */
    unsigned short  ar_pro;             /**< format of protocol address   */
    unsigned char   ar_hln;             /**< length of hardware address   */
    unsigned char   ar_pln;             /**< length of protocol address   */
    unsigned short  ar_op;              /**< ARP opcode (command)         */
    unsigned char   ar_sha[ETHER_ADDR_LEN];   /**< sender hardware address      */
    uint32_t        ar_sip;             /**< sender IP address            */
    unsigned char   ar_tha[ETHER_ADDR_LEN];   /**< target hardware address      */
    uint32_t        ar_tip;             /**< target IP address            */
} __attribute__ ((packed)) ;
typedef struct sr_arp_hdr sr_arp_hdr_t;

#define sr_IFACE_NAMELEN 32

#endif /* -- SR_PROTOCOL_H -- */