networking/udhcp/common.c - busybox - Git at Google

 /* vi: set sw=4 ts=4: */
 /*
  * Rewrite by Russ Dill <Russ.Dill@asu.edu> July 2001
  *
  * Licensed under GPLv2, see file LICENSE in this source tree.
  */
 #include "common.h"

 #if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
 unsigned dhcp_verbose;
 #endif

 const uint8_t MAC_BCAST_ADDR[6] ALIGN2 = {
 	0xff, 0xff, 0xff, 0xff, 0xff, 0xff
 };

 #if ENABLE_UDHCPC || ENABLE_UDHCPD
 /* Supported options are easily added here.
  * See RFC2132 for more options.
  * OPTION_REQ: these options are requested by udhcpc (unless -o).
  */
 const struct dhcp_optflag dhcp_optflags[] = {
 	/* 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_HOST          | OPTION_REQ, 0x0c }, /* DHCP_HOST_NAME     */
 	{ OPTION_U16                              , 0x0d }, /* DHCP_BOOT_SIZE     */
 	{ OPTION_STRING_HOST          | 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           */
 //TODO: why do we request DHCP_BROADCAST? Can't we assume that
 //in the unlikely case it is different from typical N.N.255.255,
 //server would let us know anyway?
 	{ OPTION_IP                   | OPTION_REQ, 0x1c }, /* DHCP_BROADCAST     */
 	{ OPTION_IP_PAIR | OPTION_LIST            , 0x21 }, /* DHCP_ROUTES        */
 	{ OPTION_STRING_HOST                      , 0x28 }, /* DHCP_NIS_DOMAIN    */
 	{ OPTION_IP | OPTION_LIST                 , 0x29 }, /* DHCP_NIS_SERVER    */
 	{ 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_ERR_MESSAGE   */
 //TODO: must be combined with 'sname' and 'file' handling:
 	{ OPTION_STRING_HOST                      , 0x42 }, /* DHCP_TFTP_SERVER_NAME */
 	{ OPTION_STRING                           , 0x43 }, /* DHCP_BOOT_FILE     */
 //TODO: not a string, but a set of LASCII strings:
 //	{ OPTION_STRING                           , 0x4D }, /* DHCP_USER_CLASS    */
 	{ OPTION_STRING                           , 0x64 }, /* DHCP_PCODE         */
 	{ OPTION_STRING                           , 0x65 }, /* DHCP_TCODE         */
 #if ENABLE_FEATURE_UDHCP_RFC3397
 	{ OPTION_DNS_STRING | OPTION_LIST         , 0x77 }, /* DHCP_DOMAIN_SEARCH */
 	{ OPTION_SIP_SERVERS                      , 0x78 }, /* DHCP_SIP_SERVERS   */
 #endif
 	{ OPTION_STATIC_ROUTES | OPTION_LIST      , 0x79 }, /* DHCP_STATIC_ROUTES */
 #if ENABLE_FEATURE_UDHCP_8021Q
 	{ OPTION_U16                              , 0x84 }, /* DHCP_VLAN_ID       */
 	{ OPTION_U8                               , 0x85 }, /* DHCP_VLAN_PRIORITY */
 #endif
 	{ OPTION_STRING                           , 0xd1 }, /* DHCP_PXE_CONF_FILE */
 	{ OPTION_STRING                           , 0xd2 }, /* DHCP_PXE_PATH_PREFIX */
 	{ OPTION_U32                              , 0xd3 }, /* DHCP_REBOOT_TIME   */
 	{ OPTION_6RD                              , 0xd4 }, /* DHCP_6RD           */
 	{ OPTION_STATIC_ROUTES | OPTION_LIST      , 0xf9 }, /* DHCP_MS_STATIC_ROUTES */
 	{ OPTION_STRING                           , 0xfc }, /* DHCP_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      */
 //looks like these opts will work just fine even without these defs:
 //	{ OPTION_STRING                           , 0x3c }, /* DHCP_VENDOR        */
 //	/* not really a string: */
 //	{ OPTION_STRING                           , 0x3d }, /* DHCP_CLIENT_ID     */
 	{ 0, 0 } /* zeroed terminating entry */
 };

 /* Used for converting options from incoming packets to env variables
  * for udhcpc script, and for setting options for udhcpd via
  * "opt OPTION_NAME OPTION_VALUE" directives in udhcpd.conf file.
  */
 /* Must match dhcp_optflags[] 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       */
 	"routes" "\0"           /* DHCP_ROUTES          */
 	"nisdomain" "\0"        /* DHCP_NIS_DOMAIN      */
 	"nissrv" "\0"           /* DHCP_NIS_SERVER      */
 	"ntpsrv" "\0"           /* DHCP_NTP_SERVER      */
 	"wins" "\0"             /* DHCP_WINS_SERVER     */
 	"lease" "\0"            /* DHCP_LEASE_TIME      */
 	"serverid" "\0"         /* DHCP_SERVER_ID       */
 	"message" "\0"          /* DHCP_ERR_MESSAGE     */
 	"tftp" "\0"             /* DHCP_TFTP_SERVER_NAME*/
 	"bootfile" "\0"         /* DHCP_BOOT_FILE       */
 //	"userclass" "\0"        /* DHCP_USER_CLASS      */
 	"tzstr" "\0"            /* DHCP_PCODE           */
 	"tzdbstr" "\0"          /* DHCP_TCODE           */
 #if ENABLE_FEATURE_UDHCP_RFC3397
 	"search" "\0"           /* DHCP_DOMAIN_SEARCH   */
 // doesn't work in udhcpd.conf since OPTION_SIP_SERVERS
 // is not handled yet by "string->option" conversion code:
 	"sipsrv" "\0"           /* DHCP_SIP_SERVERS     */
 #endif
 	"staticroutes" "\0"     /* DHCP_STATIC_ROUTES   */
 #if ENABLE_FEATURE_UDHCP_8021Q
 	"vlanid" "\0"           /* DHCP_VLAN_ID         */
 	"vlanpriority" "\0"     /* DHCP_VLAN_PRIORITY   */
 #endif
 	"pxeconffile" "\0"      /* DHCP_PXE_CONF_FILE   */
 	"pxepathprefix" "\0"    /* DHCP_PXE_PATH_PREFIX */
 	"reboottime" "\0"       /* DHCP_REBOOT_TIME     */
 	"ip6rd" "\0"            /* DHCP_6RD             */
 	"msstaticroutes" "\0"   /* DHCP_MS_STATIC_ROUTES*/
 	"wpad" "\0"             /* DHCP_WPAD            */
 	;
 #endif

 /* Lengths of the option types in binary form.
  * Used by:
  * udhcp_str2optset: to determine how many bytes to allocate.
  * xmalloc_optname_optval: to estimate string length
  * from binary option length: (option[LEN] / dhcp_option_lengths[opt_type])
  * is the number of elements, multiply it by one element's string width
  * (len_of_option_as_string[opt_type]) and you know how wide string you need.
  */
 const uint8_t dhcp_option_lengths[] ALIGN1 = {
 	[OPTION_IP] =      4,
 	[OPTION_IP_PAIR] = 8,
 //	[OPTION_BOOLEAN] = 1,
 	[OPTION_STRING] =  1,  /* ignored by udhcp_str2optset */
 	[OPTION_STRING_HOST] = 1,  /* ignored by udhcp_str2optset */
 #if ENABLE_FEATURE_UDHCP_RFC3397
 	[OPTION_DNS_STRING] = 1,  /* ignored by both udhcp_str2optset and xmalloc_optname_optval */
 	[OPTION_SIP_SERVERS] = 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,
 	[OPTION_6RD] =    12,  /* ignored by udhcp_str2optset */
 	/* The above value was chosen as follows:
 	 * len_of_option_as_string[] for this option is >60: it's a string of the form
 	 * "32 128 ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff 255.255.255.255 ".
 	 * Each additional ipv4 address takes 4 bytes in binary option and appends
 	 * another "255.255.255.255 " 16-byte string. We can set [OPTION_6RD] = 4
 	 * but this severely overestimates string length: instead of 16 bytes,
 	 * it adds >60 for every 4 bytes in binary option.
 	 * We cheat and declare here that option is in units of 12 bytes.
 	 * This adds more than 60 bytes for every three ipv4 addresses - more than enough.
 	 * (Even 16 instead of 12 should work, but let's be paranoid).
 	 */
 };


 #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

 unsigned FAST_FUNC udhcp_option_idx(const char *name, const char *option_strings)
 {
 	int n = index_in_strings(option_strings, name);
 	if (n >= 0)
 		return n;

 	{
 		char *buf, *d;
 		const char *s;

 		s = option_strings;
 		while (*s)
 			s += strlen(s) + 1;

 		d = buf = xzalloc(s - option_strings);
 		s = option_strings;
 		while (!(*s == '\0' && s[1] == '\0')) {
 			*d++ = (*s == '\0' ? ' ' : *s);
 			s++;
 		}
 		bb_error_msg_and_die("unknown option '%s', known options: %s", name, buf);
 	}
 }

 /* Get an option with bounds checking (warning, result is not aligned) */
 uint8_t* FAST_FUNC udhcp_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) {
  complain:
 			bb_simple_error_msg("bad packet, malformed option field");
 			return NULL;
 		}

 		/* DHCP_PADDING and DHCP_END have no [len] byte */
 		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;
 		}

 		if (rem <= OPT_LEN)
 			goto complain; /* complain and return NULL */
 		len = 2 + optionptr[OPT_LEN];
 		rem -= len;
 		if (rem < 0)
 			goto complain; /* complain and return NULL */

 		if (optionptr[OPT_CODE] == code) {
 			if (optionptr[OPT_LEN] == 0) {
 				/* So far no valid option with length 0 known.
 				 * Having this check means that searching
 				 * for DHCP_MESSAGE_TYPE need not worry
 				 * that returned pointer might be unsafe
 				 * to dereference.
 				 */
 				goto complain; /* complain and return NULL */
 			}
 			log_option("option found", optionptr);
 			return optionptr + OPT_DATA;
 		}

 		if (optionptr[OPT_CODE] == DHCP_OPTION_OVERLOAD) {
 			if (len >= 3)
 				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;
 }

 uint8_t* FAST_FUNC udhcp_get_option32(struct dhcp_packet *packet, int code)
 {
 	uint8_t *r = udhcp_get_option(packet, code);
 	if (r) {
 		if (r[-OPT_DATA + OPT_LEN] != 4)
 			r = NULL;
 	}
 	return r;
 }

 /* Return the position of the 'end' option (no bounds checking) */
 int FAST_FUNC udhcp_end_option(uint8_t *optionptr)
 {
 	int i = 0;

 	while (optionptr[i] != DHCP_END) {
 		if (optionptr[i] != DHCP_PADDING)
 			i += optionptr[i + OPT_LEN] + OPT_DATA-1;
 		i++;
 	}
 	return i;
 }

 /* Add an option (supplied in binary form) to the options.
  * Option format: [code][len][data1][data2]..[dataLEN]
  */
 void FAST_FUNC udhcp_add_binary_option(struct dhcp_packet *packet, uint8_t *addopt)
 {
 	unsigned len;
 	uint8_t *optionptr = packet->options;
 	unsigned end = udhcp_end_option(optionptr);

 	len = OPT_DATA + addopt[OPT_LEN];
 	/* end position + (option code/length + addopt length) + end option */
 	if (end + len + 1 >= DHCP_OPTIONS_BUFSIZE) {
 //TODO: learn how to use overflow option if we exhaust packet->options[]
 		bb_error_msg("option 0x%02x did not fit into the packet",
 				addopt[OPT_CODE]);
 		return;
 	}
 	log_option("adding option", addopt);
 	memcpy(optionptr + end, addopt, len);
 	optionptr[end + len] = DHCP_END;
 }

 #if ENABLE_UDHCPC || ENABLE_UDHCPD
 /* Add an one to four byte option to a packet */
 void FAST_FUNC udhcp_add_simple_option(struct dhcp_packet *packet, uint8_t code, uint32_t data)
 {
 	const struct dhcp_optflag *dh;

 	for (dh = dhcp_optflags; dh->code; dh++) {
 		if (dh->code == code) {
 			uint8_t option[6], len;

 			option[OPT_CODE] = code;
 			len = dhcp_option_lengths[dh->flags & OPTION_TYPE_MASK];
 			option[OPT_LEN] = len;
 			if (BB_BIG_ENDIAN)
 				data <<= 8 * (4 - len);
 			/* Assignment is unaligned! */
 			move_to_unaligned32(&option[OPT_DATA], data);
 			udhcp_add_binary_option(packet, option);
 			return;
 		}
 	}

 	bb_error_msg("can't add option 0x%02x", code);
 }
 #endif

 /* Find option 'code' in opt_list */
 struct option_set* FAST_FUNC udhcp_find_option(struct option_set *opt_list, uint8_t 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;
 	return NULL;
 }

 /* Parse string to IP in network order */
 int FAST_FUNC udhcp_str2nip(const char *str, void *arg)
 {
 	len_and_sockaddr *lsa;

 	lsa = host_and_af2sockaddr(str, 0, AF_INET);
 	if (!lsa)
 		return 0;
 	/* arg maybe unaligned */
 	move_to_unaligned32((uint32_t*)arg, lsa->u.sin.sin_addr.s_addr);
 	free(lsa);
 	return 1;
 }

 /* udhcp_str2optset:
  * Parse string option representation to binary form and add it to opt_list.
  * Called to parse "udhcpc -x OPTNAME:OPTVAL"
  * and to parse udhcpd.conf's "opt OPTNAME OPTVAL" directives.
  */
 /* helper: add an option to the opt_list */
 #if !ENABLE_UDHCPC6
 #define attach_option(opt_list, optflag, buffer, length, dhcpv6) \
 	attach_option(opt_list, optflag, buffer, length)
 #endif
 static NOINLINE void attach_option(
 		struct option_set **opt_list,
 		const struct dhcp_optflag *optflag,
 		char *buffer,
 		int length,
 		bool dhcpv6)
 {
 	IF_NOT_UDHCPC6(bool dhcpv6 = 0;)
 	struct option_set *existing;
 	char *allocated = NULL;

 	if ((optflag->flags & OPTION_TYPE_MASK) == OPTION_BIN) {
 		const char *end;
 		allocated = xstrdup(buffer); /* more than enough */
 		end = hex2bin(allocated, buffer, 255);
 		if (errno)
 			bb_error_msg_and_die("malformed hex string '%s'", buffer);
 		length = end - allocated;
 		buffer = allocated;
 	}
 #if ENABLE_FEATURE_UDHCP_RFC3397
 	if ((optflag->flags & OPTION_TYPE_MASK) == OPTION_DNS_STRING) {
 		/* reuse buffer and length for RFC1035-formatted string */
 		allocated = buffer = (char *)dname_enc(/*NULL, 0,*/ buffer, &length);
 	}
 #endif

 	existing = udhcp_find_option(*opt_list, optflag->code);
 	if (!existing) {
 		struct option_set *new, **curr;

 		/* make a new option */
 		log2("attaching option %02x to list", optflag->code);
 		new = xmalloc(sizeof(*new));
 		if (!dhcpv6) {
 			new->data = xmalloc(length + OPT_DATA);
 			new->data[OPT_CODE] = optflag->code;
 			new->data[OPT_LEN] = length;
 			memcpy(new->data + OPT_DATA, buffer, length);
 		} else {
 			new->data = xmalloc(length + D6_OPT_DATA);
 			new->data[D6_OPT_CODE] = optflag->code >> 8;
 			new->data[D6_OPT_CODE + 1] = optflag->code & 0xff;
 			new->data[D6_OPT_LEN] = length >> 8;
 			new->data[D6_OPT_LEN + 1] = length & 0xff;
 			memcpy(new->data + D6_OPT_DATA, buffer,
 					length);
 		}

 		curr = opt_list;
 		while (*curr && (*curr)->data[OPT_CODE] < optflag->code)
 			curr = &(*curr)->next;

 		new->next = *curr;
 		*curr = new;
 		goto ret;
 	}

 	if (optflag->flags & OPTION_LIST) {
 		unsigned old_len;

 		/* add it to an existing option */
 		log2("attaching option %02x to existing member of list", optflag->code);
 		old_len = existing->data[OPT_LEN];
 		if (old_len + length < 255) {
 			/* actually 255 is ok too, but adding a space can overlow it */

 			existing->data = xrealloc(existing->data, OPT_DATA + 1 + old_len + length);
 // So far dhcp_optflags[] has no OPTION_STRING[_HOST] | OPTION_LIST items
 #if 0
 			if ((optflag->flags & OPTION_TYPE_MASK) == OPTION_STRING
 			 || (optflag->flags & OPTION_TYPE_MASK) == OPTION_STRING_HOST
 			) {
 				/* add space separator between STRING options in a list */
 				existing->data[OPT_DATA + old_len] = ' ';
 				old_len++;
 			}
 #endif

 			memcpy(existing->data + OPT_DATA + old_len, buffer, length);
 			existing->data[OPT_LEN] = old_len + length;
 		} /* else, ignore the data, we could put this in a second option in the future */
 	} /* else, ignore the new data */

  ret:
 	free(allocated);
 }

 int FAST_FUNC udhcp_str2optset(const char *const_str, void *arg,
 		const struct dhcp_optflag *optflags, const char *option_strings,
 		bool dhcpv6)
 {
 	struct option_set **opt_list = arg;
 	char *opt;
 	char *str;
 	const struct dhcp_optflag *optflag;
 	struct dhcp_optflag userdef_optflag;
 	unsigned optcode;
 	int retval;
 	/* IP_PAIR needs 8 bytes, STATIC_ROUTES needs 9 max */
 	char buffer[9] ALIGNED(4);
 	uint16_t *result_u16 = (uint16_t *) buffer;
 	uint32_t *result_u32 = (uint32_t *) buffer;

 	/* Cheat, the only *const* str possible is "" */
 	str = (char *) const_str;
 	opt = strtok(str, " \t=:");
 	if (!opt)
 		return 0;

 	optcode = bb_strtou(opt, NULL, 0);
 	if (!errno && optcode < 255) {
 		/* Raw (numeric) option code.
 		 * Initially assume binary (hex-str), but if "str" or 'str'
 		 * is seen later, switch to STRING.
 		 */
 		userdef_optflag.flags = OPTION_BIN;
 		userdef_optflag.code = optcode;
 		optflag = &userdef_optflag;
 	} else {
 		optflag = &optflags[udhcp_option_idx(opt, option_strings)];
 	}

 	/* Loop to handle OPTION_LIST case, else execute just once */
 	retval = 0;
 	do {
 		int length;
 		char *val;

 		if (optflag->flags == OPTION_BIN) {
 			val = strtok(NULL, ""); /* do not split "'q w e'" */
 			if (val) trim(val);
 		} else
 			val = strtok(NULL, ", \t");
 		if (!val)
 			break;

 		length = dhcp_option_lengths[optflag->flags & OPTION_TYPE_MASK];
 		retval = 0;
 		opt = buffer; /* new meaning for variable opt */

 		switch (optflag->flags & OPTION_TYPE_MASK) {
 		case OPTION_IP:
 			retval = udhcp_str2nip(val, buffer);
 			break;
 		case OPTION_IP_PAIR:
 			retval = udhcp_str2nip(val, buffer);
 			val = strtok(NULL, ", \t/-");
 			if (!val)
 				retval = 0;
 			if (retval)
 				retval = udhcp_str2nip(val, buffer + 4);
 			break;
  case_OPTION_STRING:
 		case OPTION_STRING:
 		case OPTION_STRING_HOST:
 #if ENABLE_FEATURE_UDHCP_RFC3397
 		case OPTION_DNS_STRING:
 #endif
 			length = strnlen(val, 254);
 			if (length > 0) {
 				opt = val;
 				retval = 1;
 			}
 			break;
 //		case OPTION_BOOLEAN: {
 //			static const char no_yes[] ALIGN1 = "no\0yes\0";
 //			buffer[0] = retval = index_in_strings(no_yes, val);
 //			retval++; /* 0 - bad; 1: "no" 2: "yes" */
 //			break;
 //		}
 		case OPTION_U8:
 			buffer[0] = bb_strtou32(val, NULL, 0);
 			retval = (errno == 0);
 			break;
 		/* htonX are macros in older libc's, using temp var
 		 * in code below for safety */
 		/* TODO: use bb_strtoX? */
 		case OPTION_U16: {
 			uint32_t tmp = bb_strtou32(val, NULL, 0);
 			*result_u16 = htons(tmp);
 			retval = (errno == 0 /*&& tmp < 0x10000*/);
 			break;
 		}
 //		case OPTION_S16: {
 //			long tmp = bb_strtoi32(val, NULL, 0);
 //			*result_u16 = htons(tmp);
 //			retval = (errno == 0);
 //			break;
 //		}
 		case OPTION_U32: {
 			uint32_t tmp = bb_strtou32(val, NULL, 0);
 			*result_u32 = htonl(tmp);
 			retval = (errno == 0);
 			break;
 		}
 		case OPTION_S32: {
 			int32_t tmp = bb_strtoi32(val, NULL, 0);
 			*result_u32 = htonl(tmp);
 			retval = (errno == 0);
 			break;
 		}
 		case OPTION_STATIC_ROUTES: {
 			/* Input: "a.b.c.d/m" */
 			/* Output: mask(1 byte),pfx(0-4 bytes),gw(4 bytes) */
 			unsigned mask;
 			char *slash = strchr(val, '/');
 			if (slash) {
 				*slash = '\0';
 				retval = udhcp_str2nip(val, buffer + 1);
 				buffer[0] = mask = bb_strtou(slash + 1, NULL, 10);
 				val = strtok(NULL, ", \t/-");
 				if (!val || mask > 32 || errno)
 					retval = 0;
 				if (retval) {
 					length = ((mask + 7) >> 3) + 5;
 					retval = udhcp_str2nip(val, buffer + (length - 4));
 				}
 			}
 			break;
 		}
 		case OPTION_BIN:
 			/* Raw (numeric) option code. Is it a string? */
 			if (val[0] == '"' || val[0] == '\'') {
 				char delim = val[0];
 				char *end = last_char_is(val + 1, delim);
 				if (end) {
 					*end = '\0';
 					val++;
 					userdef_optflag.flags = OPTION_STRING;
 					goto case_OPTION_STRING;
 				}
 			}
 			/* No: hex-str option, handled in attach_option() */
 			opt = val;
 			retval = 1;
 			break;
 		default:
 			break;
 		}

 		if (retval)
 			attach_option(opt_list, optflag, opt, length, dhcpv6);
 	} while (retval && (optflag->flags & OPTION_LIST));

 	return retval;
 }

 /* note: ip is a pointer to an IPv6 in network order, possibly misaliged */
 int FAST_FUNC sprint_nip6(char *dest, /*const char *pre,*/ const uint8_t *ip)
 {
 	char hexstrbuf[16 * 2];
 	bin2hex(hexstrbuf, (void*)ip, 16);
 	return sprintf(dest, /* "%s" */
 		"%.4s:%.4s:%.4s:%.4s:%.4s:%.4s:%.4s:%.4s",
 		/* pre, */
 		hexstrbuf + 0 * 4,
 		hexstrbuf + 1 * 4,
 		hexstrbuf + 2 * 4,
 		hexstrbuf + 3 * 4,
 		hexstrbuf + 4 * 4,
 		hexstrbuf + 5 * 4,
 		hexstrbuf + 6 * 4,
 		hexstrbuf + 7 * 4
 	);
 }
	/* vi: set sw=4 ts=4: */
	/*
	* Rewrite by Russ Dill <Russ.Dill@asu.edu> July 2001
	*
	* Licensed under GPLv2, see file LICENSE in this source tree.
	*/
	#include "common.h"

	#if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
	unsigned dhcp_verbose;
	#endif

	const uint8_t MAC_BCAST_ADDR[6] ALIGN2 = {
	0xff, 0xff, 0xff, 0xff, 0xff, 0xff
	};

	#if ENABLE_UDHCPC \|\| ENABLE_UDHCPD
	/* Supported options are easily added here.
	* See RFC2132 for more options.
	* OPTION_REQ: these options are requested by udhcpc (unless -o).
	*/
	const struct dhcp_optflag dhcp_optflags[] = {
	/* 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_HOST \| OPTION_REQ, 0x0c }, /* DHCP_HOST_NAME */
	{ OPTION_U16 , 0x0d }, /* DHCP_BOOT_SIZE */
	{ OPTION_STRING_HOST \| 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 */
	//TODO: why do we request DHCP_BROADCAST? Can't we assume that
	//in the unlikely case it is different from typical N.N.255.255,
	//server would let us know anyway?
	{ OPTION_IP \| OPTION_REQ, 0x1c }, /* DHCP_BROADCAST */
	{ OPTION_IP_PAIR \| OPTION_LIST , 0x21 }, /* DHCP_ROUTES */
	{ OPTION_STRING_HOST , 0x28 }, /* DHCP_NIS_DOMAIN */
	{ OPTION_IP \| OPTION_LIST , 0x29 }, /* DHCP_NIS_SERVER */
	{ 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_ERR_MESSAGE */
	//TODO: must be combined with 'sname' and 'file' handling:
	{ OPTION_STRING_HOST , 0x42 }, /* DHCP_TFTP_SERVER_NAME */
	{ OPTION_STRING , 0x43 }, /* DHCP_BOOT_FILE */
	//TODO: not a string, but a set of LASCII strings:
	// { OPTION_STRING , 0x4D }, /* DHCP_USER_CLASS */
	{ OPTION_STRING , 0x64 }, /* DHCP_PCODE */
	{ OPTION_STRING , 0x65 }, /* DHCP_TCODE */
	#if ENABLE_FEATURE_UDHCP_RFC3397
	{ OPTION_DNS_STRING \| OPTION_LIST , 0x77 }, /* DHCP_DOMAIN_SEARCH */
	{ OPTION_SIP_SERVERS , 0x78 }, /* DHCP_SIP_SERVERS */
	#endif
	{ OPTION_STATIC_ROUTES \| OPTION_LIST , 0x79 }, /* DHCP_STATIC_ROUTES */
	#if ENABLE_FEATURE_UDHCP_8021Q
	{ OPTION_U16 , 0x84 }, /* DHCP_VLAN_ID */
	{ OPTION_U8 , 0x85 }, /* DHCP_VLAN_PRIORITY */
	#endif
	{ OPTION_STRING , 0xd1 }, /* DHCP_PXE_CONF_FILE */
	{ OPTION_STRING , 0xd2 }, /* DHCP_PXE_PATH_PREFIX */
	{ OPTION_U32 , 0xd3 }, /* DHCP_REBOOT_TIME */
	{ OPTION_6RD , 0xd4 }, /* DHCP_6RD */
	{ OPTION_STATIC_ROUTES \| OPTION_LIST , 0xf9 }, /* DHCP_MS_STATIC_ROUTES */
	{ OPTION_STRING , 0xfc }, /* DHCP_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 */
	//looks like these opts will work just fine even without these defs:
	// { OPTION_STRING , 0x3c }, /* DHCP_VENDOR */
	// /* not really a string: */
	// { OPTION_STRING , 0x3d }, /* DHCP_CLIENT_ID */
	{ 0, 0 } /* zeroed terminating entry */
	};

	/* Used for converting options from incoming packets to env variables
	* for udhcpc script, and for setting options for udhcpd via
	* "opt OPTION_NAME OPTION_VALUE" directives in udhcpd.conf file.
	*/
	/* Must match dhcp_optflags[] 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 */
	"routes" "\0" /* DHCP_ROUTES */
	"nisdomain" "\0" /* DHCP_NIS_DOMAIN */
	"nissrv" "\0" /* DHCP_NIS_SERVER */
	"ntpsrv" "\0" /* DHCP_NTP_SERVER */
	"wins" "\0" /* DHCP_WINS_SERVER */
	"lease" "\0" /* DHCP_LEASE_TIME */
	"serverid" "\0" /* DHCP_SERVER_ID */
	"message" "\0" /* DHCP_ERR_MESSAGE */
	"tftp" "\0" /* DHCP_TFTP_SERVER_NAME*/
	"bootfile" "\0" /* DHCP_BOOT_FILE */
	// "userclass" "\0" /* DHCP_USER_CLASS */
	"tzstr" "\0" /* DHCP_PCODE */
	"tzdbstr" "\0" /* DHCP_TCODE */
	#if ENABLE_FEATURE_UDHCP_RFC3397
	"search" "\0" /* DHCP_DOMAIN_SEARCH */
	// doesn't work in udhcpd.conf since OPTION_SIP_SERVERS
	// is not handled yet by "string->option" conversion code:
	"sipsrv" "\0" /* DHCP_SIP_SERVERS */
	#endif
	"staticroutes" "\0" /* DHCP_STATIC_ROUTES */
	#if ENABLE_FEATURE_UDHCP_8021Q
	"vlanid" "\0" /* DHCP_VLAN_ID */
	"vlanpriority" "\0" /* DHCP_VLAN_PRIORITY */
	#endif
	"pxeconffile" "\0" /* DHCP_PXE_CONF_FILE */
	"pxepathprefix" "\0" /* DHCP_PXE_PATH_PREFIX */
	"reboottime" "\0" /* DHCP_REBOOT_TIME */
	"ip6rd" "\0" /* DHCP_6RD */
	"msstaticroutes" "\0" /* DHCP_MS_STATIC_ROUTES*/
	"wpad" "\0" /* DHCP_WPAD */
	;
	#endif

	/* Lengths of the option types in binary form.
	* Used by:
	* udhcp_str2optset: to determine how many bytes to allocate.
	* xmalloc_optname_optval: to estimate string length
	* from binary option length: (option[LEN] / dhcp_option_lengths[opt_type])
	* is the number of elements, multiply it by one element's string width
	* (len_of_option_as_string[opt_type]) and you know how wide string you need.
	*/
	const uint8_t dhcp_option_lengths[] ALIGN1 = {
	[OPTION_IP] = 4,
	[OPTION_IP_PAIR] = 8,
	// [OPTION_BOOLEAN] = 1,
	[OPTION_STRING] = 1, /* ignored by udhcp_str2optset */
	[OPTION_STRING_HOST] = 1, /* ignored by udhcp_str2optset */
	#if ENABLE_FEATURE_UDHCP_RFC3397
	[OPTION_DNS_STRING] = 1, /* ignored by both udhcp_str2optset and xmalloc_optname_optval */
	[OPTION_SIP_SERVERS] = 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,
	[OPTION_6RD] = 12, /* ignored by udhcp_str2optset */
	/* The above value was chosen as follows:
	* len_of_option_as_string[] for this option is >60: it's a string of the form
	* "32 128 ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff 255.255.255.255 ".
	* Each additional ipv4 address takes 4 bytes in binary option and appends
	* another "255.255.255.255 " 16-byte string. We can set [OPTION_6RD] = 4
	* but this severely overestimates string length: instead of 16 bytes,
	* it adds >60 for every 4 bytes in binary option.
	* We cheat and declare here that option is in units of 12 bytes.
	* This adds more than 60 bytes for every three ipv4 addresses - more than enough.
	* (Even 16 instead of 12 should work, but let's be paranoid).
	*/
	};


	#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

	unsigned FAST_FUNC udhcp_option_idx(const char name, const char option_strings)
	{
	int n = index_in_strings(option_strings, name);
	if (n >= 0)
	return n;

	{
	char buf, d;
	const char *s;

	s = option_strings;
	while (*s)
	s += strlen(s) + 1;

	d = buf = xzalloc(s - option_strings);
	s = option_strings;
	while (!(*s == '\0' && s[1] == '\0')) {
	d++ = (s == '\0' ? ' ' : *s);
	s++;
	}
	bb_error_msg_and_die("unknown option '%s', known options: %s", name, buf);
	}
	}

	/* Get an option with bounds checking (warning, result is not aligned) */
	uint8_t* FAST_FUNC udhcp_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) {
	complain:
	bb_simple_error_msg("bad packet, malformed option field");
	return NULL;
	}

	/* DHCP_PADDING and DHCP_END have no [len] byte */
	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;
	}

	if (rem <= OPT_LEN)
	goto complain; /* complain and return NULL */
	len = 2 + optionptr[OPT_LEN];
	rem -= len;
	if (rem < 0)
	goto complain; /* complain and return NULL */

	if (optionptr[OPT_CODE] == code) {
	if (optionptr[OPT_LEN] == 0) {
	/* So far no valid option with length 0 known.
	* Having this check means that searching
	* for DHCP_MESSAGE_TYPE need not worry
	* that returned pointer might be unsafe
	* to dereference.
	*/
	goto complain; /* complain and return NULL */
	}
	log_option("option found", optionptr);
	return optionptr + OPT_DATA;
	}

	if (optionptr[OPT_CODE] == DHCP_OPTION_OVERLOAD) {
	if (len >= 3)
	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;
	}

	uint8_t* FAST_FUNC udhcp_get_option32(struct dhcp_packet *packet, int code)
	{
	uint8_t *r = udhcp_get_option(packet, code);
	if (r) {
	if (r[-OPT_DATA + OPT_LEN] != 4)
	r = NULL;
	}
	return r;
	}

	/* Return the position of the 'end' option (no bounds checking) */
	int FAST_FUNC udhcp_end_option(uint8_t *optionptr)
	{
	int i = 0;

	while (optionptr[i] != DHCP_END) {
	if (optionptr[i] != DHCP_PADDING)
	i += optionptr[i + OPT_LEN] + OPT_DATA-1;
	i++;
	}
	return i;
	}

	/* Add an option (supplied in binary form) to the options.
	* Option format: [code][len][data1][data2]..[dataLEN]
	*/
	void FAST_FUNC udhcp_add_binary_option(struct dhcp_packet packet, uint8_t addopt)
	{
	unsigned len;
	uint8_t *optionptr = packet->options;
	unsigned end = udhcp_end_option(optionptr);

	len = OPT_DATA + addopt[OPT_LEN];
	/* end position + (option code/length + addopt length) + end option */
	if (end + len + 1 >= DHCP_OPTIONS_BUFSIZE) {
	//TODO: learn how to use overflow option if we exhaust packet->options[]
	bb_error_msg("option 0x%02x did not fit into the packet",
	addopt[OPT_CODE]);
	return;
	}
	log_option("adding option", addopt);
	memcpy(optionptr + end, addopt, len);
	optionptr[end + len] = DHCP_END;
	}

	#if ENABLE_UDHCPC \|\| ENABLE_UDHCPD
	/* Add an one to four byte option to a packet */
	void FAST_FUNC udhcp_add_simple_option(struct dhcp_packet *packet, uint8_t code, uint32_t data)
	{
	const struct dhcp_optflag *dh;

	for (dh = dhcp_optflags; dh->code; dh++) {
	if (dh->code == code) {
	uint8_t option[6], len;

	option[OPT_CODE] = code;
	len = dhcp_option_lengths[dh->flags & OPTION_TYPE_MASK];
	option[OPT_LEN] = len;
	if (BB_BIG_ENDIAN)
	data <<= 8 * (4 - len);
	/* Assignment is unaligned! */
	move_to_unaligned32(&option[OPT_DATA], data);
	udhcp_add_binary_option(packet, option);
	return;
	}
	}

	bb_error_msg("can't add option 0x%02x", code);
	}
	#endif

	/* Find option 'code' in opt_list */
	struct option_set* FAST_FUNC udhcp_find_option(struct option_set *opt_list, uint8_t 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;
	return NULL;
	}

	/* Parse string to IP in network order */
	int FAST_FUNC udhcp_str2nip(const char str, void arg)
	{
	len_and_sockaddr *lsa;

	lsa = host_and_af2sockaddr(str, 0, AF_INET);
	if (!lsa)
	return 0;
	/* arg maybe unaligned */
	move_to_unaligned32((uint32_t*)arg, lsa->u.sin.sin_addr.s_addr);
	free(lsa);
	return 1;
	}

	/* udhcp_str2optset:
	* Parse string option representation to binary form and add it to opt_list.
	* Called to parse "udhcpc -x OPTNAME:OPTVAL"
	* and to parse udhcpd.conf's "opt OPTNAME OPTVAL" directives.
	*/
	/* helper: add an option to the opt_list */
	#if !ENABLE_UDHCPC6
	#define attach_option(opt_list, optflag, buffer, length, dhcpv6) \
	attach_option(opt_list, optflag, buffer, length)
	#endif
	static NOINLINE void attach_option(
	struct option_set **opt_list,
	const struct dhcp_optflag *optflag,
	char *buffer,
	int length,
	bool dhcpv6)
	{
	IF_NOT_UDHCPC6(bool dhcpv6 = 0;)
	struct option_set *existing;
	char *allocated = NULL;

	if ((optflag->flags & OPTION_TYPE_MASK) == OPTION_BIN) {
	const char *end;
	allocated = xstrdup(buffer); /* more than enough */
	end = hex2bin(allocated, buffer, 255);
	if (errno)
	bb_error_msg_and_die("malformed hex string '%s'", buffer);
	length = end - allocated;
	buffer = allocated;
	}
	#if ENABLE_FEATURE_UDHCP_RFC3397
	if ((optflag->flags & OPTION_TYPE_MASK) == OPTION_DNS_STRING) {
	/* reuse buffer and length for RFC1035-formatted string */
	allocated = buffer = (char )dname_enc(/NULL, 0,*/ buffer, &length);
	}
	#endif

	existing = udhcp_find_option(*opt_list, optflag->code);
	if (!existing) {
	struct option_set new, *curr;

	/* make a new option */
	log2("attaching option %02x to list", optflag->code);
	new = xmalloc(sizeof(*new));
	if (!dhcpv6) {
	new->data = xmalloc(length + OPT_DATA);
	new->data[OPT_CODE] = optflag->code;
	new->data[OPT_LEN] = length;
	memcpy(new->data + OPT_DATA, buffer, length);
	} else {
	new->data = xmalloc(length + D6_OPT_DATA);
	new->data[D6_OPT_CODE] = optflag->code >> 8;
	new->data[D6_OPT_CODE + 1] = optflag->code & 0xff;
	new->data[D6_OPT_LEN] = length >> 8;
	new->data[D6_OPT_LEN + 1] = length & 0xff;
	memcpy(new->data + D6_OPT_DATA, buffer,
	length);
	}

	curr = opt_list;
	while (curr && (curr)->data[OPT_CODE] < optflag->code)
	curr = &(*curr)->next;

	new->next = *curr;
	*curr = new;
	goto ret;
	}

	if (optflag->flags & OPTION_LIST) {
	unsigned old_len;

	/* add it to an existing option */
	log2("attaching option %02x to existing member of list", optflag->code);
	old_len = existing->data[OPT_LEN];
	if (old_len + length < 255) {
	/* actually 255 is ok too, but adding a space can overlow it */

	existing->data = xrealloc(existing->data, OPT_DATA + 1 + old_len + length);
	// So far dhcp_optflags[] has no OPTION_STRING[_HOST] \| OPTION_LIST items
	#if 0
	if ((optflag->flags & OPTION_TYPE_MASK) == OPTION_STRING
	\|\| (optflag->flags & OPTION_TYPE_MASK) == OPTION_STRING_HOST
	) {
	/* add space separator between STRING options in a list */
	existing->data[OPT_DATA + old_len] = ' ';
	old_len++;
	}
	#endif

	memcpy(existing->data + OPT_DATA + old_len, buffer, length);
	existing->data[OPT_LEN] = old_len + length;
	} /* else, ignore the data, we could put this in a second option in the future */
	} /* else, ignore the new data */

	ret:
	free(allocated);
	}

	int FAST_FUNC udhcp_str2optset(const char const_str, void arg,
	const struct dhcp_optflag optflags, const char option_strings,
	bool dhcpv6)
	{
	struct option_set **opt_list = arg;
	char *opt;
	char *str;
	const struct dhcp_optflag *optflag;
	struct dhcp_optflag userdef_optflag;
	unsigned optcode;
	int retval;
	/* IP_PAIR needs 8 bytes, STATIC_ROUTES needs 9 max */
	char buffer[9] ALIGNED(4);
	uint16_t result_u16 = (uint16_t ) buffer;
	uint32_t result_u32 = (uint32_t ) buffer;

	/* Cheat, the only const str possible is "" */
	str = (char *) const_str;
	opt = strtok(str, " \t=:");
	if (!opt)
	return 0;

	optcode = bb_strtou(opt, NULL, 0);
	if (!errno && optcode < 255) {
	/* Raw (numeric) option code.
	* Initially assume binary (hex-str), but if "str" or 'str'
	* is seen later, switch to STRING.
	*/
	userdef_optflag.flags = OPTION_BIN;
	userdef_optflag.code = optcode;
	optflag = &userdef_optflag;
	} else {
	optflag = &optflags[udhcp_option_idx(opt, option_strings)];
	}

	/* Loop to handle OPTION_LIST case, else execute just once */
	retval = 0;
	do {
	int length;
	char *val;

	if (optflag->flags == OPTION_BIN) {
	val = strtok(NULL, ""); /* do not split "'q w e'" */
	if (val) trim(val);
	} else
	val = strtok(NULL, ", \t");
	if (!val)
	break;

	length = dhcp_option_lengths[optflag->flags & OPTION_TYPE_MASK];
	retval = 0;
	opt = buffer; /* new meaning for variable opt */

	switch (optflag->flags & OPTION_TYPE_MASK) {
	case OPTION_IP:
	retval = udhcp_str2nip(val, buffer);
	break;
	case OPTION_IP_PAIR:
	retval = udhcp_str2nip(val, buffer);
	val = strtok(NULL, ", \t/-");
	if (!val)
	retval = 0;
	if (retval)
	retval = udhcp_str2nip(val, buffer + 4);
	break;
	case_OPTION_STRING:
	case OPTION_STRING:
	case OPTION_STRING_HOST:
	#if ENABLE_FEATURE_UDHCP_RFC3397
	case OPTION_DNS_STRING:
	#endif
	length = strnlen(val, 254);
	if (length > 0) {
	opt = val;
	retval = 1;
	}
	break;
	// case OPTION_BOOLEAN: {
	// static const char no_yes[] ALIGN1 = "no\0yes\0";
	// buffer[0] = retval = index_in_strings(no_yes, val);
	// retval++; /* 0 - bad; 1: "no" 2: "yes" */
	// break;
	// }
	case OPTION_U8:
	buffer[0] = bb_strtou32(val, NULL, 0);
	retval = (errno == 0);
	break;
	/* htonX are macros in older libc's, using temp var
	* in code below for safety */
	/* TODO: use bb_strtoX? */
	case OPTION_U16: {
	uint32_t tmp = bb_strtou32(val, NULL, 0);
	*result_u16 = htons(tmp);
	retval = (errno == 0 /&& tmp < 0x10000/);
	break;
	}
	// case OPTION_S16: {
	// long tmp = bb_strtoi32(val, NULL, 0);
	// *result_u16 = htons(tmp);
	// retval = (errno == 0);
	// break;
	// }
	case OPTION_U32: {
	uint32_t tmp = bb_strtou32(val, NULL, 0);
	*result_u32 = htonl(tmp);
	retval = (errno == 0);
	break;
	}
	case OPTION_S32: {
	int32_t tmp = bb_strtoi32(val, NULL, 0);
	*result_u32 = htonl(tmp);
	retval = (errno == 0);
	break;
	}
	case OPTION_STATIC_ROUTES: {
	/* Input: "a.b.c.d/m" */
	/* Output: mask(1 byte),pfx(0-4 bytes),gw(4 bytes) */
	unsigned mask;
	char *slash = strchr(val, '/');
	if (slash) {
	*slash = '\0';
	retval = udhcp_str2nip(val, buffer + 1);
	buffer[0] = mask = bb_strtou(slash + 1, NULL, 10);
	val = strtok(NULL, ", \t/-");
	if (!val \|\| mask > 32 \|\| errno)
	retval = 0;
	if (retval) {
	length = ((mask + 7) >> 3) + 5;
	retval = udhcp_str2nip(val, buffer + (length - 4));
	}
	}
	break;
	}
	case OPTION_BIN:
	/* Raw (numeric) option code. Is it a string? */
	if (val[0] == '"' \|\| val[0] == '\'') {
	char delim = val[0];
	char *end = last_char_is(val + 1, delim);
	if (end) {
	*end = '\0';
	val++;
	userdef_optflag.flags = OPTION_STRING;
	goto case_OPTION_STRING;
	}
	}
	/* No: hex-str option, handled in attach_option() */
	opt = val;
	retval = 1;
	break;
	default:
	break;
	}

	if (retval)
	attach_option(opt_list, optflag, opt, length, dhcpv6);
	} while (retval && (optflag->flags & OPTION_LIST));

	return retval;
	}

	/* note: ip is a pointer to an IPv6 in network order, possibly misaliged */
	int FAST_FUNC sprint_nip6(char dest, /const char pre,/ const uint8_t *ip)
	{
	char hexstrbuf[16 * 2];
	bin2hex(hexstrbuf, (void*)ip, 16);
	return sprintf(dest, /* "%s" */
	"%.4s:%.4s:%.4s:%.4s:%.4s:%.4s:%.4s:%.4s",
	/* pre, */
	hexstrbuf + 0 * 4,
	hexstrbuf + 1 * 4,
	hexstrbuf + 2 * 4,
	hexstrbuf + 3 * 4,
	hexstrbuf + 4 * 4,
	hexstrbuf + 5 * 4,
	hexstrbuf + 6 * 4,
	hexstrbuf + 7 * 4
	);
	}