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[dhcp] Add generic facility for using cached network settings
When a DHCP session is started (using autoboot or a command-line `dhcp net0'), check whether the new setting use-cached (DHCP option 175.178) is TRUE; if so, skip DHCP and rely on currently registered settings. This lets one combine a static IP with autoboot. Before checking the use-cached setting, call a weak get_cached_dhcpack() hook that can be implemented by particular builds of gPXE supporting some fashion of retrieving a cached DHCPACK packet. If one is available, it is registered as an options source, and then either that packet's option 175.178 or the user's prior manual use-cached setting can allow skipping duplicate DHCP. Using cached packets is not the default because DHCP servers are often configured to give gPXE different options than they give a vendor PXE client; in order to break the infinite loop of PXE chaining, one would need to load a gPXE with an embedded image that does something more than autoboot. Signed-off-by: Marty Connor <mdc@etherboot.org>
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/* | ||
* Copyright (C) 2009 Joshua Oreman <oremanj@rwcr.net>. | ||
* | ||
* This program is free software; you can redistribute it and/or | ||
* modify it under the terms of the GNU General Public License as | ||
* published by the Free Software Foundation; either version 2 of the | ||
* License, or any later version. | ||
* | ||
* This program is distributed in the hope that it will be useful, but | ||
* WITHOUT ANY WARRANTY; without even the implied warranty of | ||
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | ||
* General Public License for more details. | ||
* | ||
* You should have received a copy of the GNU General Public License | ||
* along with this program; if not, write to the Free Software | ||
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. | ||
*/ | ||
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FILE_LICENCE ( GPL2_OR_LATER ); | ||
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#include <stdio.h> | ||
#include <stdlib.h> | ||
#include <string.h> | ||
#include <gpxe/dhcp.h> | ||
#include <gpxe/dhcppkt.h> | ||
#include <gpxe/netdevice.h> | ||
#include <gpxe/iobuf.h> | ||
#include <gpxe/uaccess.h> | ||
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/** @file | ||
* | ||
* Cached DHCP packet handling | ||
* | ||
*/ | ||
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/** | ||
* Store cached DHCPACK packet | ||
* | ||
* @v data User pointer to cached DHCP packet data | ||
* @v len Length of cached DHCP packet data | ||
* @ret rc Return status code | ||
* | ||
* This function should be called by the architecture-specific | ||
* get_cached_dhcpack() handler. | ||
*/ | ||
void store_cached_dhcpack ( userptr_t data, size_t len ) { | ||
struct dhcp_packet *dhcppkt; | ||
struct dhcphdr *dhcphdr; | ||
struct settings *parent; | ||
int rc; | ||
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/* Create DHCP packet */ | ||
dhcppkt = zalloc ( sizeof ( *dhcppkt ) + len ); | ||
if ( ! dhcppkt ) | ||
return; | ||
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/* Fill in data for DHCP packet */ | ||
dhcphdr = ( ( ( void * ) dhcppkt ) + sizeof ( * dhcppkt ) ); | ||
copy_from_user ( dhcphdr, data, 0, len ); | ||
dhcppkt_init ( dhcppkt, dhcphdr, len ); | ||
DBG_HD ( dhcppkt->options.data, dhcppkt->options.len ); | ||
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/* Register settings on the last opened network device. | ||
* This will have the effect of registering cached settings | ||
* with a network device when "dhcp netX" is performed for that | ||
* device, which is usually what we want. | ||
*/ | ||
parent = netdev_settings ( last_opened_netdev() ); | ||
if ( ( rc = register_settings ( &dhcppkt->settings, parent ) ) != 0 ) | ||
DBG ( "DHCP could not register cached settings: %s\n", | ||
strerror ( rc ) ); | ||
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dhcppkt_put ( dhcppkt ); | ||
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DBG ( "DHCP registered cached settings\n" ); | ||
} |
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