src/net/fakedhcp.c

   1 /*
   2  * Copyright (C) 2008 Michael Brown <mbrown@fensystems.co.uk>.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License as
   6  * published by the Free Software Foundation; either version 2 of the
   7  * License, or any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful, but
  10  * WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  17  * 02110-1301, USA.
  18  *
  19  * You can also choose to distribute this program under the terms of
  20  * the Unmodified Binary Distribution Licence (as given in the file
  21  * COPYING.UBDL), provided that you have satisfied its requirements.
  22  */
  23
  24 FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
  25
  26 #include <stdint.h>
  27 #include <stdlib.h>
  28 #include <stdio.h>
  29 #include <errno.h>
  30 #include <string.h>
  31 #include <ipxe/settings.h>
  32 #include <ipxe/netdevice.h>
  33 #include <ipxe/dhcppkt.h>
  34 #include <ipxe/fakedhcp.h>
  35
  36 /** @file
  37  *
  38  * Fake DHCP packets
  39  *
  40  */
  41
  42 /**
  43  * Copy settings to DHCP packet
  44  *
  45  * @v dest              Destination DHCP packet
  46  * @v source            Source settings block
  47  * @v encapsulator      Encapsulating setting tag number, or zero
  48  * @ret rc              Return status code
  49  */
  50 static int copy_encap_settings ( struct dhcp_packet *dest,
  51                                  struct settings *source,
  52                                  unsigned int encapsulator ) {
  53         struct setting setting = { .name = "" };
  54         unsigned int subtag;
  55         unsigned int tag;
  56         void *data;
  57         int len;
  58         int rc;
  59
  60         for ( subtag = DHCP_MIN_OPTION; subtag <= DHCP_MAX_OPTION; subtag++ ) {
  61                 tag = DHCP_ENCAP_OPT ( encapsulator, subtag );
  62                 switch ( tag ) {
  63                 case DHCP_EB_ENCAP:
  64                 case DHCP_VENDOR_ENCAP:
  65                         /* Process encapsulated settings */
  66                         if ( ( rc = copy_encap_settings ( dest, source,
  67                                                           tag ) ) != 0 )
  68                                 return rc;
  69                         break;
  70                 default:
  71                         /* Copy setting, if present */
  72                         setting.tag = tag;
  73                         len = fetch_raw_setting_copy ( source, &setting, &data);
  74                         if ( len >= 0 ) {
  75                                 rc = dhcppkt_store ( dest, tag, data, len );
  76                                 free ( data );
  77                                 if ( rc != 0 )
  78                                         return rc;
  79                         }
  80                         break;
  81                 }
  82         }
  83
  84         return 0;
  85 }
  86
  87 /**
  88  * Copy settings to DHCP packet
  89  *
  90  * @v dest              Destination DHCP packet
  91  * @v source            Source settings block
  92  * @ret rc              Return status code
  93  */
  94 static int copy_settings ( struct dhcp_packet *dest,
  95                            struct settings *source ) {
  96         return copy_encap_settings ( dest, source, 0 );
  97 }
  98
  99 /**
 100  * Create fake DHCPDISCOVER packet
 101  *
 102  * @v netdev            Network device
 103  * @v data              Buffer for DHCP packet
 104  * @v max_len           Size of DHCP packet buffer
 105  * @ret rc              Return status code
 106  *
 107  * Used by external code.
 108  */
 109 int create_fakedhcpdiscover ( struct net_device *netdev,
 110                               void *data, size_t max_len ) {
 111         struct dhcp_packet dhcppkt;
 112         struct in_addr ciaddr = { 0 };
 113         int rc;
 114
 115         if ( ( rc = dhcp_create_request ( &dhcppkt, netdev, DHCPDISCOVER,
 116                                           dhcp_last_xid, ciaddr, data,
 117                                           max_len ) ) != 0 ) {
 118                 DBG ( "Could not create DHCPDISCOVER: %s\n",
 119                       strerror ( rc ) );
 120                 return rc;
 121         }
 122
 123         return 0;
 124 }
 125
 126 /**
 127  * Create fake DHCPACK packet
 128  *
 129  * @v netdev            Network device
 130  * @v data              Buffer for DHCP packet
 131  * @v max_len           Size of DHCP packet buffer
 132  * @ret rc              Return status code
 133  *
 134  * Used by external code.
 135  */
 136 int create_fakedhcpack ( struct net_device *netdev,
 137                          void *data, size_t max_len ) {
 138         struct dhcp_packet dhcppkt;
 139         int rc;
 140
 141         /* Create base DHCPACK packet */
 142         if ( ( rc = dhcp_create_packet ( &dhcppkt, netdev, DHCPACK,
 143                                          dhcp_last_xid, NULL, 0,
 144                                          data, max_len ) ) != 0 ) {
 145                 DBG ( "Could not create DHCPACK: %s\n", strerror ( rc ) );
 146                 return rc;
 147         }
 148
 149         /* Merge in globally-scoped settings, then netdev-specific
 150          * settings.  Do it in this order so that netdev-specific
 151          * settings take precedence regardless of stated priorities.
 152          */
 153         if ( ( rc = copy_settings ( &dhcppkt, NULL ) ) != 0 ) {
 154                 DBG ( "Could not set DHCPACK global settings: %s\n",
 155                       strerror ( rc ) );
 156                 return rc;
 157         }
 158         if ( ( rc = copy_settings ( &dhcppkt,
 159                                     netdev_settings ( netdev ) ) ) != 0 ) {
 160                 DBG ( "Could not set DHCPACK netdev settings: %s\n",
 161                       strerror ( rc ) );
 162                 return rc;
 163         }
 164
 165         return 0;
 166 }
 167
 168 /**
 169  * Create fake PXE Boot Server ACK packet
 170  *
 171  * @v netdev            Network device
 172  * @v data              Buffer for DHCP packet
 173  * @v max_len           Size of DHCP packet buffer
 174  * @ret rc              Return status code
 175  *
 176  * Used by external code.
 177  */
 178 int create_fakepxebsack ( struct net_device *netdev,
 179                           void *data, size_t max_len ) {
 180         struct dhcp_packet dhcppkt;
 181         struct settings *proxy_settings;
 182         struct settings *pxebs_settings;
 183         int rc;
 184
 185         /* Identify available settings */
 186         proxy_settings = find_settings ( PROXYDHCP_SETTINGS_NAME );
 187         pxebs_settings = find_settings ( PXEBS_SETTINGS_NAME );
 188         if ( ( ! proxy_settings ) && ( ! pxebs_settings ) ) {
 189                 /* No PXE boot server; return the regular DHCPACK */
 190                 return create_fakedhcpack ( netdev, data, max_len );
 191         }
 192
 193         /* Create base DHCPACK packet */
 194         if ( ( rc = dhcp_create_packet ( &dhcppkt, netdev, DHCPACK,
 195                                          dhcp_last_xid, NULL, 0,
 196                                          data, max_len ) ) != 0 ) {
 197                 DBG ( "Could not create PXE BS ACK: %s\n",
 198                       strerror ( rc ) );
 199                 return rc;
 200         }
 201
 202         /* Merge in ProxyDHCP options */
 203         if ( proxy_settings &&
 204              ( ( rc = copy_settings ( &dhcppkt, proxy_settings ) ) != 0 ) ) {
 205                 DBG ( "Could not copy ProxyDHCP settings: %s\n",
 206                       strerror ( rc ) );
 207                 return rc;
 208         }
 209
 210         /* Merge in BootServerDHCP options, if present */
 211         if ( pxebs_settings &&
 212              ( ( rc = copy_settings ( &dhcppkt, pxebs_settings ) ) != 0 ) ) {
 213                 DBG ( "Could not copy PXE BS settings: %s\n",
 214                       strerror ( rc ) );
 215                 return rc;
 216         }
 217
 218         return 0;
 219 }