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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
*
* Licensed under GPLv2, see file LICENSE in this tarball for details.
*/
#include "common.h"
#include "dhcpd.h"
#include "options.h"
/* Supported options are easily added here.
* See RFC2132 for more options.
* OPTION_REQ: these options are requested by udhcpc (unless -o).
*/
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_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 , 0x28 }, /* nisdomain */
{ OPTION_IP | OPTION_LIST , 0x29 }, /* nissrv */
{ OPTION_IP | OPTION_LIST | OPTION_REQ, 0x2a }, /* DHCP_NTP_SERVER */
{ OPTION_IP | OPTION_LIST , 0x2c }, /* DHCP_WINS_SERVER */
{ OPTION_U32 , 0x33 }, /* DHCP_LEASE_TIME */
{ OPTION_IP , 0x36 }, /* DHCP_SERVER_ID */
{ OPTION_STRING , 0x38 }, /* DHCP_MESSAGE */
{ OPTION_STRING , 0x42 }, /* tftp */
{ OPTION_STRING , 0x43 }, /* bootfile */
//TODO: not a string, but a set of LASCII strings:
// { OPTION_STRING , 0x4D }, /* userclass */
#if ENABLE_FEATURE_UDHCP_RFC3397
{ OPTION_STR1035 | OPTION_LIST , 0x77 }, /* search */
#endif
{ OPTION_STATIC_ROUTES , 0x79 }, /* DHCP_STATIC_ROUTES */
/* 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.
* These entries are only used internally by udhcp[cd]
* to correctly encode options into packets.
*/
{ OPTION_IP , 0x32 }, /* DHCP_REQUESTED_IP */
{ OPTION_U8 , 0x35 }, /* DHCP_MESSAGE_TYPE */
{ OPTION_U16 , 0x39 }, /* DHCP_MAX_SIZE */
{ OPTION_STRING , 0x3C }, /* DHCP_VENDOR */
{ OPTION_STRING , 0x3D }, /* DHCP_CLIENT_ID */
{ 0, 0 } /* zeroed terminating entry */
};
/* Used for converting options from incoming packets to env variables
* for udhcpc stript, and for setting options for udhcpd via
* "opt OPTION_NAME OPTION_VALUE" directives in udhcpd.conf file.
*/
/* Must match dhcp_options[] order */
const char dhcp_option_strings[] ALIGN1 =
"subnet" "\0" /* DHCP_SUBNET */
"timezone" "\0" /* DHCP_TIME_OFFSET */
"router" "\0" /* DHCP_ROUTER */
"timesrv" "\0" /* DHCP_TIME_SERVER */
// "namesrv" "\0" /* DHCP_NAME_SERVER */
"dns" "\0" /* DHCP_DNS_SERVER */
"logsrv" "\0" /* DHCP_LOG_SERVER */
// "cookiesrv" "\0" /* DHCP_COOKIE_SERVER */
"lprsrv" "\0" /* DHCP_LPR_SERVER */
"hostname" "\0" /* DHCP_HOST_NAME */
"bootsize" "\0" /* DHCP_BOOT_SIZE */
"domain" "\0" /* DHCP_DOMAIN_NAME */
"swapsrv" "\0" /* DHCP_SWAP_SERVER */
"rootpath" "\0" /* DHCP_ROOT_PATH */
"ipttl" "\0" /* DHCP_IP_TTL */
"mtu" "\0" /* DHCP_MTU */
"broadcast" "\0" /* DHCP_BROADCAST */
"nisdomain" "\0" /* */
"nissrv" "\0" /* */
"ntpsrv" "\0" /* DHCP_NTP_SERVER */
"wins" "\0" /* DHCP_WINS_SERVER */
"lease" "\0" /* DHCP_LEASE_TIME */
"serverid" "\0" /* DHCP_SERVER_ID */
"message" "\0" /* DHCP_MESSAGE */
"tftp" "\0"
"bootfile" "\0"
// "userclass" "\0"
#if ENABLE_FEATURE_UDHCP_RFC3397
"search" "\0"
#endif
// "staticroutes" is only used to set udhcpc environment, it doesn't work
// in udhcpd.conf since OPTION_STATIC_ROUTES is not handled yet:
"staticroutes" "\0" /* DHCP_STATIC_ROUTES */
/* 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_UDHCP_RFC3397
[OPTION_STR1035] = 1,
#endif
[OPTION_U8] = 1,
[OPTION_U16] = 2,
[OPTION_S16] = 2,
[OPTION_U32] = 4,
[OPTION_S32] = 4,
/* Just like OPTION_STRING, we use minimum length here */
[OPTION_STATIC_ROUTES] = 5,
};
#if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 2
static void log_option(const char *pfx, const uint8_t *opt)
{
if (dhcp_verbose >= 2) {
char buf[256 * 2 + 2];
*bin2hex(buf, (void*) (opt + OPT_DATA), opt[OPT_LEN]) = '\0';
bb_info_msg("%s: 0x%02x %s", pfx, opt[OPT_CODE], buf);
}
}
#else
# define log_option(pfx, opt) ((void)0)
#endif
/* get an option with bounds checking (warning, result is not aligned). */
uint8_t* FAST_FUNC get_option(struct dhcp_packet *packet, int code)
{
uint8_t *optionptr;
int len;
int rem;
int overload = 0;
enum {
FILE_FIELD101 = FILE_FIELD * 0x101,
SNAME_FIELD101 = SNAME_FIELD * 0x101,
};
/* option bytes: [code][len][data1][data2]..[dataLEN] */
optionptr = packet->options;
rem = sizeof(packet->options);
while (1) {
if (rem <= 0) {
bb_error_msg("bogus packet, malformed option field");
return NULL;
}
if (optionptr[OPT_CODE] == DHCP_PADDING) {
rem--;
optionptr++;
continue;
}
if (optionptr[OPT_CODE] == DHCP_END) {
if ((overload & FILE_FIELD101) == FILE_FIELD) {
/* can use packet->file, and didn't look at it yet */
overload |= FILE_FIELD101; /* "we looked at it" */
optionptr = packet->file;
rem = sizeof(packet->file);
continue;
}
if ((overload & SNAME_FIELD101) == SNAME_FIELD) {
/* can use packet->sname, and didn't look at it yet */
overload |= SNAME_FIELD101; /* "we looked at it" */
optionptr = packet->sname;
rem = sizeof(packet->sname);
continue;
}
break;
}
len = 2 + optionptr[OPT_LEN];
rem -= len;
if (rem < 0)
continue; /* complain and return NULL */
if (optionptr[OPT_CODE] == code) {
log_option("Option found", optionptr);
return optionptr + OPT_DATA;
}
if (optionptr[OPT_CODE] == DHCP_OPTION_OVERLOAD) {
overload |= optionptr[OPT_DATA];
/* fall through */
}
optionptr += len;
}
/* log3 because udhcpc uses it a lot - very noisy */
log3("Option 0x%02x not found", code);
return NULL;
}
/* return the position of the 'end' option (no bounds checking) */
int FAST_FUNC end_option(uint8_t *optionptr)
{
int i = 0;
while (optionptr[i] != DHCP_END) {
if (optionptr[i] != DHCP_PADDING)
i += optionptr[i + OPT_LEN] + 1;
i++;
}
return i;
}
/* add an option string to the options */
/* option bytes: [code][len][data1][data2]..[dataLEN] */
int FAST_FUNC 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;
}
log_option("Adding option", string);
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 FAST_FUNC 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);
/* Assignment is unaligned! */
move_to_unaligned32(&option[OPT_DATA], data);
return add_option_string(optionptr, option);
}
}
bb_error_msg("can't add option 0x%02x", code);
return 0;
}
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