dhcprelya.h

/* Copyright (c) 2007-2012 Sergey Matveychuk Yandex, LLC.  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. 4. Neither the name
 * of the company nor the names of its contributors may be used to endorse or
 * promote products derived from this software without specific prior written
 * permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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. */

#ifndef _DHCP_H
#define _DHCP_H
#include <time.h>
#include <sys/types.h>
#include <sys/mac.h>
#include <sys/queue.h>
#include <net/ethernet.h>
#include <netinet/in_systm.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <netinet/udp.h>
#include <pcap.h>
#include <libutil.h>
#include <sys/queue.h>
#include <syslog.h>

#define	IF_MAX		100	/* Max interfaces supported */
#define	SERVERS_MAX	10	/* Max servers supported */

/* Error codes */
#define	EX_OK		0
#define EX_MEM		16
#define EX_RES		32
#define EX_USAGE	64
#define EX_NOHOST	68
#define EX_UNAVAILABLE	69

#define INTF_NAME_LEN	16
#define ETH_ADDR_LEN	6

#define DHCP_UDP_OVERHEAD	(20 + /* IP header */                   \
				 8)	/* UDP header */
#define DHCP_SNAME_LEN		64
#define DHCP_FILE_LEN		128
#define DHCP_FIXED_NON_UDP	236
#define DHCP_FIXED_LEN		(DHCP_FIXED_NON_UDP + DHCP_UDP_OVERHEAD)
/* Everything but options. */
#define DHCP_MTU_MAX		1500
#define DHCP_OPTION_LEN		(DHCP_MTU_MAX - DHCP_FIXED_LEN)
#define DHCP_COOKIE_LEN		4

/* BOOTP (rfc951) message types */
#define BOOTREQUEST	1
#define BOOTREPLY	2

struct dhcp_packet {
	uint8_t op;		/* 0: Message opcode/type */
	uint8_t htype;		/* 1: Hardware addr type (net/if_types.h) */
	uint8_t hlen;		/* 2: Hardware addr length */
	uint8_t hops;		/* 3: Number of relay agent hops from client */
	uint32_t xid;		/* 4: Transaction ID */
	uint16_t secs;		/* 8: Seconds since client started looking */
	uint16_t flags;		/* 10: Flag bits */
	struct in_addr ciaddr;	/* 12: Client IP address (if already in use) */
	struct in_addr yiaddr;	/* 16: Client IP address */
	struct in_addr siaddr;	/* 20: IP address of next server to talk to */
	struct in_addr giaddr;	/* 24: DHCP relay agent IP address */
	unsigned char chaddr[16];	/* 28: Client hardware address */
	char sname[DHCP_SNAME_LEN];	/* 44: Server name */
	char file[DHCP_FILE_LEN];	/* 108: Boot filename */
	unsigned char options[DHCP_OPTION_LEN];
	/* 236: Optional parameters (actual length dependent on MTU). */
};

typedef in_addr_t ip_addr_t;

struct interface {
	int idx;
	int fd;
	char name[INTF_NAME_LEN];
	ip_addr_t ip;
	ip_addr_t mask;
	uint8_t mac[6];
	int bpf;
	pcap_t *cap;
	int srv_num;
	int *srvrs;
};

struct dhcp_server {
	char *name;
	struct sockaddr_in sockaddr;
};

STAILQ_HEAD(queue_head, queue) q_head;
struct queue {
	uint8_t *packet;
	size_t len;
	int if_idx;
	ip_addr_t ip_dst;

	 STAILQ_ENTRY(queue) entries;
};

/* Global options */
extern unsigned debug, max_packet_size;

/* utils.c */
short ip_checksum(const char *addr, int count);
char *print_mac(uint8_t *s, char *buf);
char *print_ip(ip_addr_t ip, char *buf);
char *print_xid(uint32_t ip, char *buf);
void logd(int log_level, char *fmt,...);
int get_bool_value(const char *str);

/* net_utils.c */
int get_mac(char *if_name, char *if_mac);
int get_ip(char *iname, ip_addr_t *ip, ip_addr_t *mask);

/* Plugins support */
#define MAX_PLUGINS 20
#define PLUGIN_PATH "/usr/local/lib/"

struct plugin_options {
	char *option_line;
	 SLIST_ENTRY(plugin_options) next;
};
typedef
SLIST_HEAD(opt_head, plugin_options)
plugin_options_head_t;

/* Be aware:
 * 
 * client_request() gets a packet with link-level headers send_to_server() gets
 * a stripped packet server_answer()  gets a stripped packet send_to_client()
 * gets a packet with link-level header */
struct plugin_data {
	char *name;
	int (*init) (plugin_options_head_t *poptions);
	void (*destroy) ();
	/* packet buffer could be reallocated in functions bellow */
	int (*client_request) (const struct interface *intf,
			        uint8_t **packet, size_t *psize);
	int (*send_to_server) (const struct sockaddr_in *server,
			        uint8_t **packet, size_t *psize);
	int (*server_answer) (const struct sockaddr_in *server,
			       uint8_t **packet, size_t *psize);
	int (*send_to_client) (const struct sockaddr_in *server,
			     const struct interface *intf, uint8_t **packet,
			        size_t *psize);
};

#endif