537 lines
16 KiB
C
537 lines
16 KiB
C
/* options.c
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DHCP options parsing and reassembly. */
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/*
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* Copyright (c) 1995, 1996 The Internet Software Consortium.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of The Internet Software Consortium nor the names
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* of its contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE INTERNET SOFTWARE CONSORTIUM AND
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* CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
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* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE INTERNET SOFTWARE CONSORTIUM OR
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
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* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* This software has been written for the Internet Software Consortium
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* by Ted Lemon <mellon@fugue.com> in cooperation with Vixie
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* Enterprises. To learn more about the Internet Software Consortium,
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* see ``http://www.vix.com/isc''. To learn more about Vixie
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* Enterprises, see ``http://www.vix.com''.
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*/
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#ifndef lint
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static char copyright[] =
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"$Id: options.c,v 1.1.1.1 1996/10/03 06:33:25 mrg Exp $ Copyright (c) 1995, 1996 The Internet Software Consortium. All rights reserved.\n";
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#endif /* not lint */
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#define DHCP_OPTION_DATA
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#include "dhcpd.h"
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/* Parse all available options out of the specified packet. */
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void parse_options (packet)
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struct packet *packet;
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{
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/* Initially, zero all option pointers. */
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memset (packet -> options, 0, sizeof (packet -> options));
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/* If we don't see the magic cookie, there's nothing to parse. */
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if (memcmp (packet -> raw -> options, DHCP_OPTIONS_COOKIE, 4)) {
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packet -> options_valid = 0;
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return;
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}
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/* Go through the options field, up to the end of the packet
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or the End field. */
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parse_option_buffer (packet, &packet -> raw -> options [4],
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packet -> packet_length - DHCP_FIXED_NON_UDP - 4);
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/* If we parsed a DHCP Option Overload option, parse more
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options out of the buffer(s) containing them. */
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if (packet -> options_valid
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&& packet -> options [DHO_DHCP_OPTION_OVERLOAD].data) {
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if (packet -> options [DHO_DHCP_OPTION_OVERLOAD].data [0] & 1)
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parse_option_buffer (packet,
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packet -> raw -> file,
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sizeof packet -> raw -> file);
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if (packet -> options [DHO_DHCP_OPTION_OVERLOAD].data [0] & 2)
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parse_option_buffer (packet,
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packet -> raw -> sname,
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sizeof packet -> raw -> sname);
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}
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}
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/* Parse options out of the specified buffer, storing addresses of option
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values in packet -> options and setting packet -> options_valid if no
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errors are encountered. */
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void parse_option_buffer (packet, buffer, length)
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struct packet *packet;
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unsigned char *buffer;
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int length;
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{
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unsigned char *s, *t;
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unsigned char *end = buffer + length;
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int len;
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int code;
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for (s = buffer; *s != DHO_END && s < end; ) {
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code = s [0];
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/* Pad options don't have a length - just skip them. */
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if (code == DHO_PAD) {
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++s;
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continue;
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}
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/* All other fields (except end, see above) have a
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one-byte length. */
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len = s [1];
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/* If the length is outrageous, the options are bad. */
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if (s + len + 2 > end) {
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warn ("Option %s length %d overflows input buffer.",
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dhcp_options [code].name,
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len);
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packet -> options_valid = 0;
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return;
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}
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/* If we haven't seen this option before, just make
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space for it and copy it there. */
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if (!packet -> options [code].data) {
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if (!(t = (unsigned char *)malloc (len + 1)))
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error ("Can't allocate storage for option %s.",
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dhcp_options [code].name);
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/* Copy and NUL-terminate the option (in case it's an
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ASCII string. */
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memcpy (t, &s [2], len);
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t [len] = 0;
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packet -> options [code].len = len;
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packet -> options [code].data = t;
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} else {
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/* If it's a repeat, concatenate it to whatever
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we last saw. This is really only required
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for clients, but what the heck... */
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t = (unsigned char *)
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malloc (len
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+ packet -> options [code].len
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+ 1);
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if (!t)
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error ("Can't expand storage for option %s.",
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dhcp_options [code].name);
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memcpy (t, packet -> options [code].data,
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packet -> options [code].len);
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memcpy (t + packet -> options [code].len,
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&s [2], len);
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packet -> options [code].len += len;
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t [packet -> options [code].len] = 0;
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free (packet -> options [code].data);
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packet -> options [code].data = t;
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}
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s += len + 2;
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}
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packet -> options_valid = 1;
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}
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/* cons options into a big buffer, and then split them out into the
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three seperate buffers if needed. This allows us to cons up a set
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of vendor options using the same routine. */
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void cons_options (inpacket, outpacket, options, overload, terminate)
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struct packet *inpacket;
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struct packet *outpacket;
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struct tree_cache **options;
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int overload; /* Overload flags that may be set. */
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int terminate;
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{
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unsigned char priority_list [300];
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int priority_len;
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unsigned char buffer [4096]; /* Really big buffer... */
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int main_buffer_size;
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int mainbufix, bufix;
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int option_size;
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/* If the client has provided a maximum DHCP message size,
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use that. Otherwise, we use the default MTU size (576 bytes). */
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/* XXX Maybe it would be safe to assume that we can send a packet
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to the client that's as big as the one it sent us, even if it
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didn't specify a large MTU. */
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if (inpacket && inpacket -> options [DHO_DHCP_MAX_MESSAGE_SIZE].data) {
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main_buffer_size =
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(getUShort (inpacket -> options
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[DHO_DHCP_MAX_MESSAGE_SIZE].data)
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- DHCP_FIXED_LEN);
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/* Enforce a minimum packet size... */
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if (main_buffer_size < (576 - DHCP_FIXED_LEN))
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main_buffer_size = 576 - DHCP_FIXED_LEN;
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} else
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main_buffer_size = 576 - DHCP_FIXED_LEN;
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/* Preload the option priority list with mandatory options. */
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priority_len = 0;
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priority_list [priority_len++] = DHO_DHCP_MESSAGE_TYPE;
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priority_list [priority_len++] = DHO_DHCP_SERVER_IDENTIFIER;
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priority_list [priority_len++] = DHO_DHCP_LEASE_TIME;
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priority_list [priority_len++] = DHO_DHCP_MESSAGE;
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/* If the client has provided a list of options that it wishes
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returned, use it to prioritize. Otherwise, prioritize
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based on the default priority list. */
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if (inpacket &&
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inpacket -> options [DHO_DHCP_PARAMETER_REQUEST_LIST].data) {
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memcpy (&priority_list [priority_len],
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inpacket -> options
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[DHO_DHCP_PARAMETER_REQUEST_LIST].data,
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inpacket -> options
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[DHO_DHCP_PARAMETER_REQUEST_LIST].len);
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priority_len +=
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inpacket -> options
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[DHO_DHCP_PARAMETER_REQUEST_LIST].len;
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} else {
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memcpy (&priority_list [priority_len],
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dhcp_option_default_priority_list,
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sizeof_dhcp_option_default_priority_list);
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priority_len += sizeof_dhcp_option_default_priority_list;
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}
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/* Copy the options into the big buffer... */
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option_size = store_options (buffer,
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(main_buffer_size - 7 +
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((overload & 1) ? DHCP_FILE_LEN : 0) +
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((overload & 2) ? DHCP_SNAME_LEN : 0)),
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options, priority_list, priority_len,
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main_buffer_size,
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(main_buffer_size +
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((overload & 1) ? DHCP_FILE_LEN : 0)),
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terminate);
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/* Put the cookie up front... */
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memcpy (outpacket -> raw -> options, DHCP_OPTIONS_COOKIE, 4);
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mainbufix = 4;
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/* If we're going to have to overload, store the overload
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option at the beginning. If we can, though, just store the
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whole thing in the packet's option buffer and leave it at
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that. */
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if (option_size <= main_buffer_size - mainbufix) {
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memcpy (&outpacket -> raw -> options [mainbufix],
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buffer, option_size);
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mainbufix += option_size;
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if (mainbufix < main_buffer_size)
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outpacket -> raw -> options [mainbufix++]
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= DHO_END;
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outpacket -> packet_length = DHCP_FIXED_NON_UDP + mainbufix;
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} else {
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outpacket -> raw -> options [mainbufix++] =
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DHO_DHCP_OPTION_OVERLOAD;
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outpacket -> raw -> options [mainbufix++] = 1;
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if (option_size > main_buffer_size - mainbufix + DHCP_FILE_LEN)
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outpacket -> raw -> options [mainbufix++] = 3;
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else
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outpacket -> raw -> options [mainbufix++] = 1;
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memcpy (&outpacket -> raw -> options [mainbufix],
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buffer, main_buffer_size - mainbufix);
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bufix = main_buffer_size - mainbufix;
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outpacket -> packet_length = DHCP_FIXED_NON_UDP + mainbufix;
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if (overload & 1) {
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if (option_size - bufix <= DHCP_FILE_LEN) {
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memcpy (outpacket -> raw -> file,
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&buffer [bufix], option_size - bufix);
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mainbufix = option_size - bufix;
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if (mainbufix < DHCP_FILE_LEN)
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outpacket -> raw -> file [mainbufix++]
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= DHO_END;
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while (mainbufix < DHCP_FILE_LEN)
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outpacket -> raw -> file [mainbufix++]
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= DHO_PAD;
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} else {
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memcpy (outpacket -> raw -> file,
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&buffer [bufix], DHCP_FILE_LEN);
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bufix += DHCP_FILE_LEN;
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}
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}
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if ((overload & 2) && option_size < bufix) {
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memcpy (outpacket -> raw -> sname,
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&buffer [bufix], option_size - bufix);
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mainbufix = option_size - bufix;
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if (mainbufix < DHCP_SNAME_LEN)
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outpacket -> raw -> file [mainbufix++]
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= DHO_END;
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while (mainbufix < DHCP_SNAME_LEN)
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outpacket -> raw -> file [mainbufix++]
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= DHO_PAD;
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}
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}
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return;
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}
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/* Store all the requested options into the requested buffer. */
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int store_options (buffer, buflen, options, priority_list, priority_len,
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first_cutoff, second_cutoff, terminate)
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unsigned char *buffer;
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int buflen;
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struct tree_cache **options;
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unsigned char *priority_list;
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int priority_len;
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int first_cutoff, second_cutoff;
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int terminate;
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{
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int bufix = 0;
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int option_stored [256];
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int i;
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int ix;
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int tto;
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/* Zero out the stored-lengths array. */
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memset (option_stored, 0, sizeof option_stored);
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/* Copy out the options in the order that they appear in the
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priority list... */
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for (i = 0; i < priority_len; i++) {
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/* Code for next option to try to store. */
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int code = priority_list [i];
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int optstart;
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/* Number of bytes left to store (some may already
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have been stored by a previous pass). */
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int length;
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/* If no data is available for this option, skip it. */
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if (!options [code]) {
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continue;
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}
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/* The client could ask for things that are mandatory,
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in which case we should avoid storing them twice... */
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if (option_stored [code])
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continue;
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option_stored [code] = 1;
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/* Find the value of the option... */
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if (!tree_evaluate (options [code])) {
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continue;
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}
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/* We should now have a constant length for the option. */
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length = options [code] -> len;
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/* Do we add a NUL? */
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if (terminate && dhcp_options [code].format [0] == 't') {
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length++;
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tto = 1;
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} else {
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tto = 0;
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}
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/* Try to store the option. */
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/* If the option's length is more than 255, we must store it
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in multiple hunks. Store 255-byte hunks first. However,
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in any case, if the option data will cross a buffer
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boundary, split it across that boundary. */
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ix = 0;
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optstart = bufix;
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while (length) {
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unsigned char incr = length > 255 ? 255 : length;
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/* If this hunk of the buffer will cross a
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boundary, only go up to the boundary in this
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pass. */
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if (bufix < first_cutoff &&
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bufix + incr > first_cutoff)
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incr = first_cutoff - bufix;
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else if (bufix < second_cutoff &&
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bufix + incr > second_cutoff)
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incr = second_cutoff - bufix;
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/* If this option is going to overflow the buffer,
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skip it. */
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if (bufix + 2 + incr > buflen) {
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bufix = optstart;
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break;
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}
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/* Everything looks good - copy it in! */
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buffer [bufix] = code;
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buffer [bufix + 1] = incr;
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if (tto && incr == length) {
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memcpy (buffer + bufix + 2,
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options [code] -> value + ix,
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incr - 1);
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buffer [bufix + 2 + incr - 1] = 0;
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} else {
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memcpy (buffer + bufix + 2,
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options [code] -> value + ix, incr);
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}
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length -= incr;
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ix += incr;
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bufix += 2 + incr;
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}
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}
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return bufix;
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}
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/* Format the specified option so that a human can easily read it. */
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char *pretty_print_option (code, data, len)
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unsigned char code;
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unsigned char *data;
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int len;
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{
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static char optbuf [32768]; /* XXX */
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int hunksize = 0;
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int numhunk = -1;
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int numelem = 0;
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char fmtbuf [32];
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int i, j;
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char *op = optbuf;
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unsigned char *dp = data;
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struct in_addr foo;
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/* Figure out the size of the data. */
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for (i = 0; dhcp_options [code].format [i]; i++) {
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if (!numhunk) {
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warn ("%s: Excess information in format string: %s\n",
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dhcp_options [code].name,
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&(dhcp_options [code].format [i]));
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break;
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}
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numelem++;
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fmtbuf [i] = dhcp_options [code].format [i];
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switch (dhcp_options [code].format [i]) {
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case 'A':
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--numelem;
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fmtbuf [i] = 0;
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numhunk = 0;
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break;
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case 't':
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fmtbuf [i] = 't';
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fmtbuf [i + 1] = 0;
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numhunk = -2;
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break;
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case 'I':
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case 'l':
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case 'L':
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hunksize += 4;
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break;
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case 's':
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case 'S':
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hunksize += 2;
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break;
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case 'b':
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case 'B':
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case 'f':
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hunksize++;
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break;
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case 'e':
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break;
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default:
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warn ("%s: garbage in format string: %s\n",
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dhcp_options [code].name,
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&(dhcp_options [code].format [i]));
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break;
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}
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}
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/* Check for too few bytes... */
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if (hunksize > len) {
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warn ("%s: expecting at least %d bytes; got %d",
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dhcp_options [code].name,
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hunksize, len);
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return "<error>";
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}
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/* Check for too many bytes... */
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if (numhunk == -1 && hunksize < len)
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warn ("%s: %d extra bytes",
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dhcp_options [code].name,
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len - hunksize);
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/* If this is an array, compute its size. */
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if (!numhunk)
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numhunk = len / hunksize;
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/* See if we got an exact number of hunks. */
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if (numhunk > 0 && numhunk * hunksize < len)
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warn ("%s: %d extra bytes at end of array\n",
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dhcp_options [code].name,
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len - numhunk * hunksize);
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/* A one-hunk array prints the same as a single hunk. */
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if (numhunk < 0)
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numhunk = 1;
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/* Cycle through the array (or hunk) printing the data. */
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for (i = 0; i < numhunk; i++) {
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for (j = 0; j < numelem; j++) {
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switch (fmtbuf [j]) {
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case 't':
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strcpy (op, dp);
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break;
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case 'I':
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foo.s_addr = htonl (getULong (dp));
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strcpy (op, inet_ntoa (foo));
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dp += 4;
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break;
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case 'l':
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sprintf (op, "%ld", (long)getLong (dp));
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dp += 4;
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break;
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case 'L':
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sprintf (op, "%ld",
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(unsigned long)getULong (dp));
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dp += 4;
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break;
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case 's':
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sprintf (op, "%d", getShort (dp));
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dp += 2;
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break;
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case 'S':
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sprintf (op, "%d", getUShort (dp));
|
|
dp += 2;
|
|
break;
|
|
case 'b':
|
|
sprintf (op, "%d", *(char *)dp++);
|
|
break;
|
|
case 'B':
|
|
sprintf (op, "%d", *dp++);
|
|
break;
|
|
case 'f':
|
|
strcpy (op, *dp++ ? "true" : "false");
|
|
break;
|
|
default:
|
|
warn ("Unexpected format code %c", fmtbuf [j]);
|
|
}
|
|
op += strlen (op);
|
|
*op++ = ' ';
|
|
}
|
|
}
|
|
*--op = 0;
|
|
return optbuf;
|
|
}
|
|
|
|
|
|
|