238 lines
8.2 KiB
C
238 lines
8.2 KiB
C
/* vi: set sw=4 ts=4: */
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/*
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* options.c -- DHCP server option packet tools
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* Rewrite by Russ Dill <Russ.Dill@asu.edu> July 2001
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*
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* Licensed under GPLv2, see file LICENSE in this tarball for details.
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*/
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#include "common.h"
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#include "dhcpd.h"
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#include "options.h"
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/* Supported options are easily added here */
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const struct dhcp_option dhcp_options[] = {
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/* flags code */
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{ OPTION_IP | OPTION_REQ, 0x01 }, /* DHCP_SUBNET */
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{ OPTION_S32 , 0x02 }, /* DHCP_TIME_OFFSET */
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{ OPTION_IP | OPTION_LIST | OPTION_REQ, 0x03 }, /* DHCP_ROUTER */
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{ OPTION_IP | OPTION_LIST , 0x04 }, /* DHCP_TIME_SERVER */
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{ OPTION_IP | OPTION_LIST , 0x05 }, /* DHCP_NAME_SERVER */
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{ OPTION_IP | OPTION_LIST | OPTION_REQ, 0x06 }, /* DHCP_DNS_SERVER */
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{ OPTION_IP | OPTION_LIST , 0x07 }, /* DHCP_LOG_SERVER */
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{ OPTION_IP | OPTION_LIST , 0x08 }, /* DHCP_COOKIE_SERVER */
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{ OPTION_IP | OPTION_LIST , 0x09 }, /* DHCP_LPR_SERVER */
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{ OPTION_STRING | OPTION_REQ, 0x0c }, /* DHCP_HOST_NAME */
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{ OPTION_U16 , 0x0d }, /* DHCP_BOOT_SIZE */
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{ OPTION_STRING | OPTION_LIST | OPTION_REQ, 0x0f }, /* DHCP_DOMAIN_NAME */
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{ OPTION_IP , 0x10 }, /* DHCP_SWAP_SERVER */
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{ OPTION_STRING , 0x11 }, /* DHCP_ROOT_PATH */
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{ OPTION_U8 , 0x17 }, /* DHCP_IP_TTL */
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{ OPTION_U16 , 0x1a }, /* DHCP_MTU */
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{ OPTION_IP | OPTION_REQ, 0x1c }, /* DHCP_BROADCAST */
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{ OPTION_STRING , 0x28 }, /* nisdomain */
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{ OPTION_IP | OPTION_LIST , 0x29 }, /* nissrv */
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{ OPTION_IP | OPTION_LIST | OPTION_REQ, 0x2a }, /* DHCP_NTP_SERVER */
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{ OPTION_IP | OPTION_LIST , 0x2c }, /* DHCP_WINS_SERVER */
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{ OPTION_IP , 0x32 }, /* DHCP_REQUESTED_IP */
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{ OPTION_U32 , 0x33 }, /* DHCP_LEASE_TIME */
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{ OPTION_U8 , 0x35 }, /* dhcptype */
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{ OPTION_IP , 0x36 }, /* DHCP_SERVER_ID */
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{ OPTION_STRING , 0x38 }, /* DHCP_MESSAGE */
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{ OPTION_STRING , 0x3C }, /* DHCP_VENDOR */
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{ OPTION_STRING , 0x3D }, /* DHCP_CLIENT_ID */
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{ OPTION_STRING , 0x42 }, /* tftp */
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{ OPTION_STRING , 0x43 }, /* bootfile */
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{ OPTION_STRING , 0x4D }, /* userclass */
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#if ENABLE_FEATURE_UDHCP_RFC3397
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{ OPTION_STR1035 | OPTION_LIST , 0x77 }, /* search */
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#endif
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/* MSIE's "Web Proxy Autodiscovery Protocol" support */
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{ OPTION_STRING , 0xfc }, /* wpad */
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/* Options below have no match in dhcp_option_strings[],
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* are not passed to dhcpc scripts, and cannot be specified
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* with "option XXX YYY" syntax in dhcpd config file. */
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{ OPTION_U16 , 0x39 }, /* DHCP_MAX_SIZE */
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{ } /* zeroed terminating entry */
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};
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/* Used for converting options from incoming packets to env variables
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* for udhcpc stript */
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/* Must match dhcp_options[] order */
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const char dhcp_option_strings[] ALIGN1 =
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"subnet" "\0" /* DHCP_SUBNET */
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"timezone" "\0" /* DHCP_TIME_OFFSET */
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"router" "\0" /* DHCP_ROUTER */
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"timesrv" "\0" /* DHCP_TIME_SERVER */
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"namesrv" "\0" /* DHCP_NAME_SERVER */
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"dns" "\0" /* DHCP_DNS_SERVER */
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"logsrv" "\0" /* DHCP_LOG_SERVER */
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"cookiesrv" "\0" /* DHCP_COOKIE_SERVER */
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"lprsrv" "\0" /* DHCP_LPR_SERVER */
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"hostname" "\0" /* DHCP_HOST_NAME */
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"bootsize" "\0" /* DHCP_BOOT_SIZE */
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"domain" "\0" /* DHCP_DOMAIN_NAME */
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"swapsrv" "\0" /* DHCP_SWAP_SERVER */
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"rootpath" "\0" /* DHCP_ROOT_PATH */
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"ipttl" "\0" /* DHCP_IP_TTL */
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"mtu" "\0" /* DHCP_MTU */
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"broadcast" "\0" /* DHCP_BROADCAST */
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"nisdomain" "\0" /* */
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"nissrv" "\0" /* */
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"ntpsrv" "\0" /* DHCP_NTP_SERVER */
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"wins" "\0" /* DHCP_WINS_SERVER */
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"requestip" "\0" /* DHCP_REQUESTED_IP */
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"lease" "\0" /* DHCP_LEASE_TIME */
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"dhcptype" "\0" /* */
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"serverid" "\0" /* DHCP_SERVER_ID */
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"message" "\0" /* DHCP_MESSAGE */
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"vendorclass" "\0" /* DHCP_VENDOR */
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"clientid" "\0" /* DHCP_CLIENT_ID */
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"tftp" "\0"
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"bootfile" "\0"
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"userclass" "\0"
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#if ENABLE_FEATURE_UDHCP_RFC3397
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"search" "\0"
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#endif
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/* MSIE's "Web Proxy Autodiscovery Protocol" support */
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"wpad" "\0"
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;
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/* Lengths of the different option types */
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const uint8_t dhcp_option_lengths[] ALIGN1 = {
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[OPTION_IP] = 4,
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[OPTION_IP_PAIR] = 8,
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[OPTION_BOOLEAN] = 1,
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[OPTION_STRING] = 1,
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#if ENABLE_FEATURE_UDHCP_RFC3397
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[OPTION_STR1035] = 1,
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#endif
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[OPTION_U8] = 1,
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[OPTION_U16] = 2,
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[OPTION_S16] = 2,
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[OPTION_U32] = 4,
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[OPTION_S32] = 4
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};
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/* get an option with bounds checking (warning, result is not aligned). */
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uint8_t* FAST_FUNC get_option(struct dhcpMessage *packet, int code)
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{
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uint8_t *optionptr;
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int len;
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int rem;
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int overload = 0;
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enum {
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FILE_FIELD101 = FILE_FIELD * 0x101,
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SNAME_FIELD101 = SNAME_FIELD * 0x101,
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};
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/* option bytes: [code][len][data1][data2]..[dataLEN] */
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optionptr = packet->options;
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rem = sizeof(packet->options);
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while (1) {
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if (rem <= 0) {
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bb_error_msg("bogus packet, malformed option field");
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return NULL;
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}
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if (optionptr[OPT_CODE] == DHCP_PADDING) {
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rem--;
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optionptr++;
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continue;
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}
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if (optionptr[OPT_CODE] == DHCP_END) {
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if ((overload & FILE_FIELD101) == FILE_FIELD) {
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/* can use packet->file, and didn't look at it yet */
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overload |= FILE_FIELD101; /* "we looked at it" */
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optionptr = packet->file;
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rem = sizeof(packet->file);
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continue;
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}
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if ((overload & SNAME_FIELD101) == SNAME_FIELD) {
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/* can use packet->sname, and didn't look at it yet */
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overload |= SNAME_FIELD101; /* "we looked at it" */
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optionptr = packet->sname;
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rem = sizeof(packet->sname);
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continue;
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}
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return NULL;
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}
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len = 2 + optionptr[OPT_LEN];
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rem -= len;
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if (rem < 0)
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continue; /* complain and return NULL */
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if (optionptr[OPT_CODE] == code)
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return optionptr + OPT_DATA;
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if (optionptr[OPT_CODE] == DHCP_OPTION_OVERLOAD) {
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overload |= optionptr[OPT_DATA];
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/* fall through */
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}
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optionptr += len;
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}
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return NULL;
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}
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/* return the position of the 'end' option (no bounds checking) */
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int FAST_FUNC end_option(uint8_t *optionptr)
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{
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int i = 0;
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while (optionptr[i] != DHCP_END) {
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if (optionptr[i] != DHCP_PADDING)
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i += optionptr[i + OPT_LEN] + 1;
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i++;
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}
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return i;
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}
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/* add an option string to the options */
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/* option bytes: [code][len][data1][data2]..[dataLEN] */
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int FAST_FUNC add_option_string(uint8_t *optionptr, uint8_t *string)
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{
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int end = end_option(optionptr);
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/* end position + string length + option code/length + end option */
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if (end + string[OPT_LEN] + 2 + 1 >= DHCP_OPTIONS_BUFSIZE) {
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bb_error_msg("option 0x%02x did not fit into the packet",
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string[OPT_CODE]);
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return 0;
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}
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log1("Adding option 0x%02x", string[OPT_CODE]);
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memcpy(optionptr + end, string, string[OPT_LEN] + 2);
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optionptr[end + string[OPT_LEN] + 2] = DHCP_END;
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return string[OPT_LEN] + 2;
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}
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/* add a one to four byte option to a packet */
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int FAST_FUNC add_simple_option(uint8_t *optionptr, uint8_t code, uint32_t data)
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{
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const struct dhcp_option *dh;
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for (dh = dhcp_options; dh->code; dh++) {
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if (dh->code == code) {
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uint8_t option[6], len;
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option[OPT_CODE] = code;
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len = dhcp_option_lengths[dh->flags & TYPE_MASK];
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option[OPT_LEN] = len;
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if (BB_BIG_ENDIAN)
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data <<= 8 * (4 - len);
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/* Assignment is unaligned! */
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move_to_unaligned32(&option[OPT_DATA], data);
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return add_option_string(optionptr, option);
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}
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}
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bb_error_msg("cannot add option 0x%02x", code);
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return 0;
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}
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