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/*
* options.c -- DHCP server option packet tools
* Rewrite by Russ Dill <Russ.Dill@asu.edu> July 2001
*/
#include <stdlib.h>
#include <string.h>
#include "dhcpd.h"
#include "files.h"
#include "options.h"
#include "common.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 (__BYTE_ORDER == __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;
}
/* find option 'code' in opt_list */
struct option_set *find_option(struct option_set *opt_list, char code)
{
while (opt_list && opt_list->data[OPT_CODE] < code)
opt_list = opt_list->next;
if (opt_list && opt_list->data[OPT_CODE] == code) return opt_list;
else return NULL;
}
/* add an option to the opt_list */
void attach_option(struct option_set **opt_list, struct dhcp_option *option, char *buffer, int length)
{
struct option_set *existing, *new, **curr;
/* add it to an existing option */
if ((existing = find_option(*opt_list, option->code))) {
DEBUG(LOG_INFO, "Attaching option %s to existing member of list", option->name);
if (option->flags & OPTION_LIST) {
if (existing->data[OPT_LEN] + length <= 255) {
existing->data = realloc(existing->data,
existing->data[OPT_LEN] + length + 2);
memcpy(existing->data + existing->data[OPT_LEN] + 2, buffer, length);
existing->data[OPT_LEN] += length;
} /* else, ignore the data, we could put this in a second option in the future */
} /* else, ignore the new data */
} else {
DEBUG(LOG_INFO, "Attaching option %s to list", option->name);
/* make a new option */
new = xmalloc(sizeof(struct option_set));
new->data = xmalloc(length + 2);
new->data[OPT_CODE] = option->code;
new->data[OPT_LEN] = length;
memcpy(new->data + 2, buffer, length);
curr = opt_list;
while (*curr && (*curr)->data[OPT_CODE] < option->code)
curr = &(*curr)->next;
new->next = *curr;
*curr = new;
}
}
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