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/* vi: set sw=4 ts=4: */
/*
* options.c -- DHCP server option packet tools
* Rewrite by Russ Dill <Russ.Dill@asu.edu> July 2001
*/
#include "common.h"
#include "dhcpd.h"
#include "options.h"
/* Supported options are easily added here */
const struct dhcp_option dhcp_options[] = {
/* flags code */
{ OPTION_IP | OPTION_REQ, 0x01 }, /* DHCP_SUBNET */
{ OPTION_S32, 0x02 }, /* DHCP_TIME_OFFSET */
{ OPTION_IP | OPTION_LIST | OPTION_REQ, 0x03 }, /* DHCP_ROUTER */
{ OPTION_IP | OPTION_LIST, 0x04 }, /* DHCP_TIME_SERVER */
{ OPTION_IP | OPTION_LIST, 0x05 }, /* DHCP_NAME_SERVER */
{ OPTION_IP | OPTION_LIST | OPTION_REQ, 0x06 }, /* DHCP_DNS_SERVER */
{ OPTION_IP | OPTION_LIST, 0x07 }, /* DHCP_LOG_SERVER */
{ OPTION_IP | OPTION_LIST, 0x08 }, /* DHCP_COOKIE_SERVER */
{ OPTION_IP | OPTION_LIST, 0x09 }, /* DHCP_LPR_SERVER */
{ OPTION_STRING | OPTION_REQ, 0x0c }, /* DHCP_HOST_NAME */
{ OPTION_U16, 0x0d }, /* DHCP_BOOT_SIZE */
{ OPTION_STRING | OPTION_LIST | OPTION_REQ, 0x0f }, /* DHCP_DOMAIN_NAME */
{ OPTION_IP, 0x10 }, /* DHCP_SWAP_SERVER */
{ OPTION_STRING, 0x11 }, /* DHCP_ROOT_PATH */
{ OPTION_U8, 0x17 }, /* DHCP_IP_TTL */
{ OPTION_U16, 0x1a }, /* DHCP_MTU */
{ OPTION_IP | OPTION_REQ, 0x1c }, /* DHCP_BROADCAST */
{ OPTION_STRING | OPTION_REQ, 0x28 }, /* DHCP_NTP_SERVER */
{ OPTION_IP | OPTION_LIST | OPTION_REQ, 0x29 }, /* DHCP_WINS_SERVER */
{ OPTION_IP | OPTION_LIST | OPTION_REQ, 0x2a }, /* DHCP_REQUESTED_IP */
{ OPTION_IP | OPTION_LIST, 0x2c }, /* DHCP_LEASE_TIME */
{ OPTION_IP, 0x32 }, /* DHCP_OPTION_OVER */
{ OPTION_U32, 0x33 }, /* DHCP_MESSAGE_TYPE */
{ OPTION_U8, 0x35 }, /* DHCP_SERVER_ID */
{ OPTION_IP, 0x36 }, /* DHCP_PARAM_REQ */
{ OPTION_STRING, 0x38 }, /* DHCP_MESSAGE */
{ OPTION_STRING, 0x3C }, /* DHCP_VENDOR */
{ OPTION_STRING, 0x3D }, /* DHCP_CLIENT_ID */
{ OPTION_STRING, 0x42 }, /* "tftp" */
{ OPTION_STRING, 0x43 }, /* "bootfile" */
{ OPTION_STRING, 0x4D }, /* "userclass" */
#if ENABLE_FEATURE_RFC3397
{ OPTION_STR1035 | OPTION_LIST | OPTION_REQ, 0x77 }, /* "search" */
#endif
/* MSIE's "Web Proxy Autodiscovery Protocol" support */
{ OPTION_STRING, 0xfc }, /* "wpad" */
/* Options below have no match in dhcp_option_strings[],
* are not passed to dhcpc scripts, and cannot be specified
* with "option XXX YYY" syntax in dhcpd config file. */
{ OPTION_U16, 0x39 }, /* DHCP_MAX_SIZE */
{ } /* zeroed terminating entry */
};
/* Used for converting options from incoming packets to env variables
* for udhcpc stript */
/* Must match dhcp_options[] order */
const char dhcp_option_strings[] ALIGN1 =
"subnet" "\0" /* DHCP_SUBNET */
"timezone" "\0" /* DHCP_TIME_OFFSET */
"router" "\0" /* DHCP_ROUTER */
"timesvr" "\0" /* DHCP_TIME_SERVER */
"namesvr" "\0" /* DHCP_NAME_SERVER */
"dns" "\0" /* DHCP_DNS_SERVER */
"logsvr" "\0" /* DHCP_LOG_SERVER */
"cookiesvr" "\0" /* DHCP_COOKIE_SERVER */
"lprsvr" "\0" /* DHCP_LPR_SERVER */
"hostname" "\0" /* DHCP_HOST_NAME */
"bootsize" "\0" /* DHCP_BOOT_SIZE */
"domain" "\0" /* DHCP_DOMAIN_NAME */
"swapsvr" "\0" /* DHCP_SWAP_SERVER */
"rootpath" "\0" /* DHCP_ROOT_PATH */
"ipttl" "\0" /* DHCP_IP_TTL */
"mtu" "\0" /* DHCP_MTU */
"broadcast" "\0" /* DHCP_BROADCAST */
"nisdomain" "\0" /* DHCP_NTP_SERVER */
"nissrv" "\0" /* DHCP_WINS_SERVER */
"ntpsrv" "\0" /* DHCP_REQUESTED_IP */
"wins" "\0" /* DHCP_LEASE_TIME */
"requestip" "\0" /* DHCP_OPTION_OVER */
"lease" "\0" /* DHCP_MESSAGE_TYPE */
"dhcptype" "\0" /* DHCP_SERVER_ID */
"serverid" "\0" /* DHCP_PARAM_REQ */
"message" "\0" /* DHCP_MESSAGE */
"vendorclass" "\0" /* DHCP_VENDOR */
"clientid" "\0" /* DHCP_CLIENT_ID */
"tftp" "\0"
"bootfile" "\0"
"userclass" "\0"
#if ENABLE_FEATURE_RFC3397
"search" "\0"
#endif
/* MSIE's "Web Proxy Autodiscovery Protocol" support */
"wpad" "\0"
;
/* Lengths of the different option types */
const uint8_t dhcp_option_lengths[] ALIGN1 = {
[OPTION_IP] = 4,
[OPTION_IP_PAIR] = 8,
[OPTION_BOOLEAN] = 1,
[OPTION_STRING] = 1,
#if ENABLE_FEATURE_RFC3397
[OPTION_STR1035] = 1,
#endif
[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;
int curr = OPTION_FIELD;
optionptr = packet->options;
i = 0;
length = sizeof(packet->options);
while (1) {
if (i >= length) {
bb_error_msg("bogus packet, option fields too long");
return NULL;
}
if (optionptr[i + OPT_CODE] == code) {
if (i + 1 + optionptr[i + OPT_LEN] >= length) {
bb_error_msg("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) {
bb_error_msg("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 = sizeof(packet->file);
curr = FILE_FIELD;
} else if (curr == FILE_FIELD && (over & SNAME_FIELD)) {
optionptr = packet->sname;
i = 0;
length = sizeof(packet->sname);
curr = SNAME_FIELD;
} else
return NULL;
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 >= DHCP_OPTIONS_BUFSIZE) {
bb_error_msg("option 0x%02x did not fit into the packet",
string[OPT_CODE]);
return 0;
}
DEBUG("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)
{
const 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 = dhcp_option_lengths[dh->flags & TYPE_MASK];
option[OPT_LEN] = len;
if (BB_BIG_ENDIAN)
data <<= 8 * (4 - len);
/* This memcpy is for processors which can't
* handle a simple unaligned 32-bit assignment */
memcpy(&option[OPT_DATA], &data, 4);
return add_option_string(optionptr, option);
}
}
bb_error_msg("cannot add option 0x%02x", code);
return 0;
}
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