/* * options.c -- DHCP server option packet tools * Rewrite by Russ Dill <Russ.Dill@asu.edu> July 2001 */#include <stdlib.h>#include <string.h>#include "common.h"#include "dhcpd.h"#include "options.h"#include "files.h"/* supported options are easily added here */struct dhcp_option dhcp_options[] = {	/* name[10]	flags					code */	{"subnet",	OPTION_IP | OPTION_REQ,			0x01},	{"timezone",	OPTION_S32,				0x02},	{"router",	OPTION_IP | OPTION_LIST | OPTION_REQ,	0x03},	{"timesvr",	OPTION_IP | OPTION_LIST,		0x04},	{"namesvr",	OPTION_IP | OPTION_LIST,		0x05},	{"dns",		OPTION_IP | OPTION_LIST | OPTION_REQ,	0x06},	{"logsvr",	OPTION_IP | OPTION_LIST,		0x07},	{"cookiesvr",	OPTION_IP | OPTION_LIST,		0x08},	{"lprsvr",	OPTION_IP | OPTION_LIST,		0x09},	{"hostname",	OPTION_STRING | OPTION_REQ,		0x0c},	{"bootsize",	OPTION_U16,				0x0d},	{"domain",	OPTION_STRING | OPTION_REQ,		0x0f},	{"swapsvr",	OPTION_IP,				0x10},	{"rootpath",	OPTION_STRING,				0x11},	{"ipttl",	OPTION_U8,				0x17},	{"mtu",		OPTION_U16,				0x1a},	{"broadcast",	OPTION_IP | OPTION_REQ,			0x1c},	{"nisdomain",	OPTION_STRING | OPTION_REQ,		0x28},	{"nissrv",	OPTION_IP | OPTION_LIST | OPTION_REQ,	0x29},	{"ntpsrv",	OPTION_IP | OPTION_LIST | OPTION_REQ,	0x2a},	{"wins",	OPTION_IP | OPTION_LIST,		0x2c},	{"requestip",	OPTION_IP,				0x32},	{"lease",	OPTION_U32,				0x33},	{"dhcptype",	OPTION_U8,				0x35},	{"serverid",	OPTION_IP,				0x36},	{"message",	OPTION_STRING,				0x38},	{"tftp",	OPTION_STRING,				0x42},	{"bootfile",	OPTION_STRING,				0x43},	{"",		0x00,				0x00}};/* Lengths of the different option types */int option_lengths[] = {	[OPTION_IP] =		4,	[OPTION_IP_PAIR] =	8,	[OPTION_BOOLEAN] =	1,	[OPTION_STRING] =	1,	[OPTION_U8] =		1,	[OPTION_U16] =		2,	[OPTION_S16] =		2,	[OPTION_U32] =		4,	[OPTION_S32] =		4};/* get an option with bounds checking (warning, not aligned). */uint8_t *get_option(struct dhcpMessage *packet, int code){	int i, length;	uint8_t *optionptr;	int over = 0, done = 0, curr = OPTION_FIELD;	optionptr = packet->options;	i = 0;	length = 308;	while (!done) {		if (i >= length) {			LOG(LOG_WARNING, "bogus packet, option fields too long.");			return NULL;		}		if (optionptr[i + OPT_CODE] == code) {			if (i + 1 + optionptr[i + OPT_LEN] >= length) {				LOG(LOG_WARNING, "bogus packet, option fields too long.");				return NULL;			}			return optionptr + i + 2;		}		switch (optionptr[i + OPT_CODE]) {		case DHCP_PADDING:			i++;			break;		case DHCP_OPTION_OVER:			if (i + 1 + optionptr[i + OPT_LEN] >= length) {				LOG(LOG_WARNING, "bogus packet, option fields too long.");				return NULL;			}			over = optionptr[i + 3];			i += optionptr[OPT_LEN] + 2;			break;		case DHCP_END:			if (curr == OPTION_FIELD && over & FILE_FIELD) {				optionptr = packet->file;				i = 0;				length = 128;				curr = FILE_FIELD;			} else if (curr == FILE_FIELD && over & SNAME_FIELD) {				optionptr = packet->sname;				i = 0;				length = 64;				curr = SNAME_FIELD;			} else done = 1;			break;		default:			i += optionptr[OPT_LEN + i] + 2;		}	}	return NULL;}/* return the position of the 'end' option (no bounds checking) */int end_option(uint8_t *optionptr){	int i = 0;	while (optionptr[i] != DHCP_END) {		if (optionptr[i] == DHCP_PADDING) i++;		else i += optionptr[i + OPT_LEN] + 2;	}	return i;}/* add an option string to the options (an option string contains an option code, * length, then data) */int add_option_string(uint8_t *optionptr, uint8_t *string){	int end = end_option(optionptr);	/* end position + string length + option code/length + end option */	if (end + string[OPT_LEN] + 2 + 1 >= 308) {		LOG(LOG_ERR, "Option 0x%02x did not fit into the packet!", string[OPT_CODE]);		return 0;	}	DEBUG(LOG_INFO, "adding option 0x%02x", string[OPT_CODE]);	memcpy(optionptr + end, string, string[OPT_LEN] + 2);	optionptr[end + string[OPT_LEN] + 2] = DHCP_END;	return string[OPT_LEN] + 2;}/* add a one to four byte option to a packet */int add_simple_option(uint8_t *optionptr, uint8_t code, uint32_t data){	struct dhcp_option *dh;	for (dh=dhcp_options; dh->code; dh++) {		if (dh->code == code) {			uint8_t option[6], len;			option[OPT_CODE] = code;			len = option_lengths[dh->flags & TYPE_MASK];			option[OPT_LEN] = len;			if (BB_BIG_ENDIAN) data <<= 8 * (4 - len);			/* This memcpy is for broken processors which can't			 * handle a simple unaligned 32-bit assignment */			memcpy(&option[OPT_DATA], &data, 4);			return add_option_string(optionptr, option);		}	}	DEBUG(LOG_ERR, "Could not add option 0x%02x", code);	return 0;}