dhcp-librawnet.h

this is sample about DHCP-agent

/* $Header: /cvsroot/dhcp-agent/dhcp-agent/src/dhcp-librawnet.h,v 1.21 2003/07/05 19:18:17 actmodern Exp $
 *
 * Copyright 2002 Thamer Alharbash
 *
 * 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.
 * 3. The names of the authors may not be used to endorse or promote
 * products derived from this software without specific prior
 * written permission.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 *
 */

#ifndef DHCP_LIBRAWNET_H
#define DHCP_LIBRAWNET_H

/* type definitions. */

typedef uint8_t    dhcp_opt_tag_t;
typedef size_t     dhcp_opt_len_t;
typedef uint16_t   dhcp_opt_type_t;
typedef uint16_t   dhcp_opt_val_type_t;

/* forward declare dhcp_opt to typedef function pointers below. */
struct dhcp_opt;

/* typedef of dhcp option function pointers. */

/* converters from external data to internal */
typedef int (*dhcp_opt_from_string)(struct dhcp_opt *opt, const char *input);
typedef int (*dhcp_opt_from_user_string)(struct dhcp_opt *opt, list_t *input_list);
typedef int (*dhcp_opt_from_network)(struct dhcp_opt *opt, const uint8_t *data, size_t len);

/* converts from internal data to other data formats. */
typedef void *(*dhcp_opt_to_network_data)(struct dhcp_opt *opt);
typedef void *(*dhcp_opt_to_host_data)(struct dhcp_opt *opt);
typedef char *(*dhcp_opt_to_user_string)(struct dhcp_opt *opt);
typedef char *(*dhcp_opt_to_string)(struct dhcp_opt *opt);

/* data structures. */

/* interface control object:
 * we store dnet's interface handle, 
 * and interface_entry structure. 
 * We need the entry structure
 */
typedef struct {
    intf_t *interface_handle;
    struct intf_entry *interface_entry;
} interface_control_t;

/* DHCP fixed header -- before dhcp options. */

/* Size of header independant of any padding
 * sizeof() the structure may return. */

#define DHCP_FIXEDHDR_LEN 236

typedef struct {
    uint8_t op;
    uint8_t htype;
    uint8_t hlen;
    uint8_t hops;
    uint32_t xid;
    uint16_t secs;
    uint16_t flags;
    uint32_t ciaddr;
    uint32_t yiaddr;
    uint32_t siaddr;
    uint32_t giaddr;

#define DHCP_CHADDR_SIZE 16
    unsigned char chaddr[DHCP_CHADDR_SIZE];
#define DHCP_SNAME_SIZE 64
    unsigned char sname[DHCP_SNAME_SIZE];
#define DHCP_FILE_SIZE 128
    unsigned char file[DHCP_FILE_SIZE];

    /* options go here. */
} dhcphdr;

/* the data destructor. */
typedef void (*dhcp_opt_data_destroy)(struct dhcp_opt *opt);

typedef struct dhcp_opt_attr {

    dhcp_opt_tag_t      tag;         /* tag                     */
    dhcp_opt_len_t      len;         /* member length in octets */
    dhcp_opt_val_type_t type;        /* type of opt             */
    dhcp_opt_val_type_t val_type;    /* type of val             */

    /* data extraction routines. */
    dhcp_opt_to_network_data    to_network_data;          /* to network data representation. */
    dhcp_opt_to_user_string     to_user_string;           /* to user string representation. */
    dhcp_opt_to_string          to_internal_string;       /* to internal string representation. */

    /* data creation routines. */
    dhcp_opt_from_network       from_network;                /* network data to internal. */
    dhcp_opt_from_user_string   from_user_string;            /* user string to internal.  */
    dhcp_opt_from_string        from_internal_string;        /* string to internal.       */

    dhcp_opt_data_destroy                 destroy;           /* destroy option datum. */

} dhcp_opt_attr_t;

/* the dhcp option object. */

typedef struct dhcp_opt {
    void *val;                       /* value        */
    size_t num;                      /* num          */
    dhcp_opt_attr_t *opt_attr;       /* attributes   */
} dhcp_opt_t;


/* DHCP object *
 * for packet assembly/disassembly. */
typedef struct {
    dhcphdr fixedheader;        /* DHCP fixed header. */
    uint32_t magic_cookie;      /* Magic cookie. */
    list_t *options;            /* Option list. */
} dhcp_obj;

/* 
 * Other packet objects.
 * 
 * We use these to create a single interface
 * for creating custom packeting.
 * 
 */

typedef struct {
    struct eth_hdr header;
} eth_obj;

typedef struct {
    struct ip_hdr header;
} ip_obj;

typedef struct {
    struct arp_hdr header;
    struct arp_ethip arp_data;
} arp_obj;

typedef struct {
    struct icmp_hdr icmp_header;
    union icmp_msg icmp_msg;
} icmp_obj;

typedef struct {
    struct udp_hdr header;
} udp_obj;

/* 
 * DHCP raw network object.
 * 
 * We do all our network transmission
 * through this data structure.
 * 
 */

typedef struct {

    /* we should not interface directly with any of these members
     * above the rawnet layer: FIXME -- unfortunately we do. */

    pcap_t *pcap;               /* packet capturing device (pcap). */
    int pcap_fd;                /* file descriptor we can select on for pcap. */
    eth_t *eth;                 /* ethernet device handler (libdnet). */

    uint16_t src_port, dst_port; /* udp ports for writing packets. */
    char *device;               /* device name. */

    char *packet_data;          /* packet data. */
    int packet_len;             /* total length of packet. */

    struct timeval tstamp;      /* timestamp. */

    eth_addr_t chw_addr;        /* our hardware address. */
    ip_addr_t cip_addr;         /* our ip address. */

    eth_addr_t *fake_hw_addr;   /* our fake hardware address. */

    int promiscuous;            /* run in promiscuous mode flag. */
    int mtu;                    /* mtu setting. */
    interface_control_t
    *intf_handle;               /* interface control handle. */

    /* 
     * Data objects
     * 
     * After reception of packets on the wire
     * they're aligned and placed into these
     * objects.
     * 
     */

    uint8_t type;               /* Type of data:
                                 * ARP, ICMP DHCP */
    char *pcap_filter;          /* low level pcap filter. */

    /* Packet data. */

    eth_obj *ether_p;
    ip_obj *ip_p;
    arp_obj *arp_p;
    icmp_obj *icmp_p;
    udp_obj *udp_p;
    dhcp_obj *dhcp_p;

} rawnet_t;

/* constants. */

/* Reasonable defaults in case services db isn't up to date. */
#define BOOTP_CLIENT 68
#define BOOTP_SERVER 67

/* Raw net types for packets. */

#define RAWNET_UNKNOWN 0
#define RAWNET_ARP 1
#define RAWNET_ICMP 2
#define RAWNET_DHCP 3

/* Raw net return types when
 * receiving packets. */

#define RAWNET_OK 0
#define RAWNET_PCAP_ERROR -1
#define RAWNET_ERROR -2 /* generic error. */
#define RAWNET_MALFORMED_PACKET -3
#define RAWNET_UNHANDLED -4
#define RAWNET_TIMEOUT -5
#define RAWNET_USER_INTERRUPT -6

/* DHCP Type messages */

# define DHCP_DISCOVER_TM 1
# define DHCP_OFFER_TM    2
# define DHCP_REQUEST_TM  3
# define DHCP_DECLINE_TM  4
# define DHCP_DHCPACK_TM  5
# define DHCP_DHCPNAK_TM  6
# define DHCP_RELEASE_TM  7

/* BOOTP Types */

#define DHCP_BOOTP_REQUEST 1
#define DHCP_BOOTP_REPLY 2

/* Flags */

#define DHCP_BROADCAST_FLAG 0x8000

/* Option tags. */

/* (this is me trying to make constant names out of long option
 * names. let the comedy ensue!)
 */

# define TAG_DHCP_PAD                           0
# define TAG_DHCP_SUBNET_MASK                   1
# define TAG_DHCP_TIME_OFFSET                   2
# define TAG_DHCP_ROUTER                        3
# define TAG_DHCP_TIME_SERVER                   4
# define TAG_DHCP_NAME_SERVER                   5
# define TAG_DHCP_DOMAIN_NAME_SERVER            6
# define TAG_DHCP_LOG_SERVER                    7
# define TAG_DHCP_COOKIE_SERVER                 8
# define TAG_DHCP_LPR_SERVER                    9
# define TAG_DHCP_IMPRESS_SERVER               10
# define TAG_DHCP_RESOURCE_LOCATION_SERVER     11
# define TAG_DHCP_HOST_NAME                    12
# define TAG_DHCP_BOOT_FILE_SIZE               13
# define TAG_DHCP_MERIT_DUMP_FILE              14
# define TAG_DHCP_DOMAIN_NAME                  15
# define TAG_DHCP_SWAP_SERVER                  16
# define TAG_DHCP_ROOT_PATH                    17
# define TAG_DHCP_EXTENSIONS_PATH              18
# define TAG_DHCP_IP_FORWARDING                19
# define TAG_DHCP_NON_LOCAL_SOURCE_ROUTING     20
# define TAG_DHCP_POLICY_FILTER                21
# define TAG_DHCP_MAX_DGRAM_REASSUMBLY_SIZE    22
# define TAG_DHCP_IP_TIME_TO_LIVE              23
# define TAG_DHCP_MTU_AGING_TIMEOUT            24
# define TAG_DHCP_MTU_PLATEAU_TABLE            25
# define TAG_DHCP_INTERFACE_MTU                26