7a4e212fe2
This avoids confusing other code by insisting that we have e.g. a filename consisting of 128 zero bytes.
211 lines
5.8 KiB
C
211 lines
5.8 KiB
C
/*
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* Copyright (C) 2008 Michael Brown <mbrown@fensystems.co.uk>.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of the
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* License, or any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#include <stdint.h>
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#include <stdlib.h>
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#include <stdio.h>
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#include <errno.h>
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#include <string.h>
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#include <gpxe/netdevice.h>
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#include <gpxe/dhcp.h>
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#include <gpxe/dhcpopts.h>
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#include <gpxe/dhcppkt.h>
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/** @file
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*
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* DHCP packets
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*
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*/
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/**
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* Calculate used length of an IPv4 field within a DHCP packet
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*
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* @v data Field data
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* @v len Length of field
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* @ret used Used length of field
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*/
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static size_t used_len_ipv4 ( const void *data, size_t len __unused ) {
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const struct in_addr *in = data;
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return ( in->s_addr ? sizeof ( *in ) : 0 );
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}
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/**
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* Calculate used length of a string field within a DHCP packet
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*
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* @v data Field data
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* @v len Length of field
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* @ret used Used length of field
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*/
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static size_t used_len_string ( const void *data, size_t len ) {
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return strnlen ( data, len );
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}
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/** A dedicated field within a DHCP packet */
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struct dhcp_packet_field {
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/** Settings tag number */
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unsigned int tag;
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/** Offset within DHCP packet */
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uint16_t offset;
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/** Length of field */
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uint16_t len;
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/** Calculate used length of field
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*
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* @v data Field data
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* @v len Length of field
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* @ret used Used length of field
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*/
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size_t ( * used_len ) ( const void *data, size_t len );
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};
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/** Declare a dedicated field within a DHCP packet
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*
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* @v _tag Settings tag number
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* @v _field Field name
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* @v _used_len Function to calculate used length of field
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*/
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#define DHCP_PACKET_FIELD( _tag, _field, _used_len ) { \
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.tag = (_tag), \
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.offset = offsetof ( struct dhcphdr, _field ), \
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.len = sizeof ( ( ( struct dhcphdr * ) 0 )->_field ), \
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.used_len = _used_len, \
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}
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/** Dedicated fields within a DHCP packet */
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static struct dhcp_packet_field dhcp_packet_fields[] = {
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DHCP_PACKET_FIELD ( DHCP_EB_YIADDR, yiaddr, used_len_ipv4 ),
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DHCP_PACKET_FIELD ( DHCP_EB_SIADDR, siaddr, used_len_ipv4 ),
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DHCP_PACKET_FIELD ( DHCP_TFTP_SERVER_NAME, sname, used_len_string ),
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DHCP_PACKET_FIELD ( DHCP_BOOTFILE_NAME, file, used_len_string ),
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};
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/**
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* Get address of a DHCP packet field
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*
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* @v dhcphdr DHCP packet header
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* @v field DHCP packet field
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* @ret data Packet field data
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*/
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static inline void * dhcp_packet_field ( struct dhcphdr *dhcphdr,
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struct dhcp_packet_field *field ) {
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return ( ( ( void * ) dhcphdr ) + field->offset );
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}
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/**
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* Find DHCP packet field corresponding to settings tag number
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*
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* @v tag Settings tag number
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* @ret field DHCP packet field, or NULL
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*/
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static struct dhcp_packet_field *
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find_dhcp_packet_field ( unsigned int tag ) {
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struct dhcp_packet_field *field;
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unsigned int i;
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for ( i = 0 ; i < ( sizeof ( dhcp_packet_fields ) /
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sizeof ( dhcp_packet_fields[0] ) ) ; i++ ) {
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field = &dhcp_packet_fields[i];
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if ( field->tag == tag )
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return field;
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}
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return NULL;
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}
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/**
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* Store value of DHCP packet setting
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*
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* @v dhcppkt DHCP packet
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* @v tag Setting tag number
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* @v data Setting data, or NULL to clear setting
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* @v len Length of setting data
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* @ret rc Return status code
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*/
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int dhcppkt_store ( struct dhcp_packet *dhcppkt, unsigned int tag,
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const void *data, size_t len ) {
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struct dhcp_packet_field *field;
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int rc;
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/* If this is a special field, fill it in */
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if ( ( field = find_dhcp_packet_field ( tag ) ) != NULL ) {
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if ( len > field->len )
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return -ENOSPC;
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memcpy ( dhcp_packet_field ( dhcppkt->dhcphdr, field ),
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data, len );
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return 0;
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}
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/* Otherwise, use the generic options block */
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rc = dhcpopt_store ( &dhcppkt->options, tag, data, len );
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/* Update our used-length field */
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dhcppkt->len = ( offsetof ( struct dhcphdr, options ) +
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dhcppkt->options.len );
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return rc;
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}
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/**
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* Fetch value of DHCP packet setting
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*
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* @v dhcppkt DHCP packet
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* @v tag Setting tag number
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* @v data Buffer to fill with setting data
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* @v len Length of buffer
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* @ret len Length of setting data, or negative error
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*/
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int dhcppkt_fetch ( struct dhcp_packet *dhcppkt, unsigned int tag,
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void *data, size_t len ) {
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struct dhcp_packet_field *field;
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void *field_data;
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size_t field_len;
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/* If this is a special field, return it */
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if ( ( field = find_dhcp_packet_field ( tag ) ) != NULL ) {
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field_data = dhcp_packet_field ( dhcppkt->dhcphdr, field );
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field_len = field->used_len ( field_data, field->len );
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if ( ! field_len )
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return -ENOENT;
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if ( len > field_len )
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len = field_len;
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memcpy ( data, field_data, len );
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return field_len;
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}
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/* Otherwise, use the generic options block */
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return dhcpopt_fetch ( &dhcppkt->options, tag, data, len );
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}
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/**
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* Initialise prepopulated DHCP packet
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*
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* @v dhcppkt Uninitialised DHCP packet
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* @v data Memory for DHCP packet data
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* @v max_len Length of memory for DHCP packet data
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*
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* The memory content must already be filled with valid DHCP options.
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* A zeroed block counts as a block of valid DHCP options.
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*/
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void dhcppkt_init ( struct dhcp_packet *dhcppkt, void *data, size_t len ) {
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dhcppkt->dhcphdr = data;
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dhcppkt->max_len = len;
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dhcpopt_init ( &dhcppkt->options, &dhcppkt->dhcphdr->options,
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( len - offsetof ( struct dhcphdr, options ) ) );
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dhcppkt->len = ( offsetof ( struct dhcphdr, options ) +
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dhcppkt->options.len );
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}
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