554 lines
16 KiB
C
554 lines
16 KiB
C
/*
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* Copyright (C) 2006 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 <string.h>
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#include <errno.h>
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#include <assert.h>
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#include <byteswap.h>
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#include <gpxe/if_ether.h>
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#include <gpxe/netdevice.h>
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#include <gpxe/udp.h>
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#include <gpxe/dhcp.h>
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/** @file
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*
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* Dynamic Host Configuration Protocol
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*
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*/
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/** DHCP operation types
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*
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* This table maps from DHCP message types (i.e. values of the @c
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* DHCP_MESSAGE_TYPE option) to values of the "op" field within a DHCP
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* packet.
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*/
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static const uint8_t dhcp_op[] = {
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[DHCPDISCOVER] = BOOTP_REQUEST,
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[DHCPOFFER] = BOOTP_REPLY,
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[DHCPREQUEST] = BOOTP_REQUEST,
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[DHCPDECLINE] = BOOTP_REQUEST,
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[DHCPACK] = BOOTP_REPLY,
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[DHCPNAK] = BOOTP_REPLY,
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[DHCPRELEASE] = BOOTP_REQUEST,
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[DHCPINFORM] = BOOTP_REQUEST,
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};
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/** Raw option data for options common to all DHCP requests */
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static uint8_t dhcp_request_options_data[] = {
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DHCP_MAX_MESSAGE_SIZE, DHCP_WORD ( ETH_MAX_MTU ),
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DHCP_VENDOR_CLASS_ID,
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DHCP_STRING ( 'E', 't', 'h', 'e', 'r', 'b', 'o', 'o', 't' ),
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DHCP_PARAMETER_REQUEST_LIST,
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DHCP_OPTION ( DHCP_SUBNET_MASK, DHCP_ROUTERS, DHCP_HOST_NAME ),
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DHCP_END
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};
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/**
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* Name a DHCP packet type
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*
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* @v msgtype DHCP message type
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* @ret string DHCP mesasge type name
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*/
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static inline const char * dhcp_message_type_name ( unsigned int msgtype ) {
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switch ( msgtype ) {
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case DHCPDISCOVER: return "DHCPDISCOVER";
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case DHCPOFFER: return "DHCPOFFER";
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case DHCPREQUEST: return "DHCPREQUEST";
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case DHCPDECLINE: return "DHCPDECLINE";
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case DHCPACK: return "DHCPACK";
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case DHCPNAK: return "DHCPNAK";
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case DHCPRELEASE: return "DHCPRELEASE";
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case DHCPINFORM: return "DHCPINFORM";
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default: return "DHCP<invalid>";
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}
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}
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/** Options common to all DHCP requests */
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static struct dhcp_option_block dhcp_request_options = {
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.data = dhcp_request_options_data,
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.max_len = sizeof ( dhcp_request_options_data ),
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.len = sizeof ( dhcp_request_options_data ),
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};
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/**
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* Set option within DHCP packet
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*
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* @v dhcppkt DHCP packet
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* @v tag DHCP option tag
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* @v data New value for DHCP option
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* @v len Length of value, in bytes
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* @ret rc Return status code
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*
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* Sets the option within the first available options block within the
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* DHCP packet. Option blocks are tried in the order specified by @c
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* dhcp_option_block_fill_order.
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*
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* The magic options @c DHCP_EB_YIADDR and @c DHCP_EB_SIADDR are
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* intercepted and inserted into the appropriate fixed fields within
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* the DHCP packet. The option @c DHCP_OPTION_OVERLOAD is silently
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* ignored, since our DHCP packet assembly method relies on always
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* having option overloading in use.
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*/
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static int set_dhcp_packet_option ( struct dhcp_packet *dhcppkt,
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unsigned int tag, const void *data,
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size_t len ) {
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struct dhcphdr *dhcphdr = dhcppkt->dhcphdr;
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struct dhcp_option_block *options;
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struct dhcp_option *option = NULL;
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/* Special-case the magic options */
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switch ( tag ) {
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case DHCP_OPTION_OVERLOAD:
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/* Hard-coded in packets we create; always ignore */
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return 0;
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case DHCP_EB_YIADDR:
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memcpy ( &dhcphdr->yiaddr, data, sizeof ( dhcphdr->yiaddr ) );
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return 0;
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case DHCP_EB_SIADDR:
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memcpy ( &dhcphdr->siaddr, data, sizeof ( dhcphdr->siaddr ) );
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return 0;
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default:
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/* Continue processing as normal */
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break;
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}
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/* Set option in first available options block */
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for ( options = dhcppkt->options ;
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options < &dhcppkt->options[NUM_OPT_BLOCKS] ; options++ ) {
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option = set_dhcp_option ( options, tag, data, len );
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if ( option )
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break;
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}
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/* Update DHCP packet length */
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dhcppkt->len = ( offsetof ( typeof ( *dhcppkt->dhcphdr ), options )
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+ dhcppkt->options[OPTS_MAIN].len );
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return ( option ? 0 : -ENOSPC );
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}
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/**
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* Set options within DHCP packet
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*
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* @v dhcppkt DHCP packet
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* @v options DHCP option block, or NULL
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* @v encapsulator Encapsulating option, or zero
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* @ret rc Return status code
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*
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* Copies options with the specified encapsulator from DHCP options
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* blocks into a DHCP packet. Most options are copied verbatim.
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* Recognised encapsulated options fields are handled as such.
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*
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* @c options may specify a single options block, or be left as NULL
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* in order to copy options from all registered options blocks.
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*/
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static int set_dhcp_packet_encap_options ( struct dhcp_packet *dhcppkt,
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struct dhcp_option_block *options,
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unsigned int encapsulator ) {
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unsigned int subtag;
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unsigned int tag;
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struct dhcp_option *option;
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int rc;
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for ( subtag = DHCP_MIN_OPTION; subtag <= DHCP_MAX_OPTION; subtag++ ) {
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tag = DHCP_ENCAP_OPT ( encapsulator, subtag );
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switch ( tag ) {
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case DHCP_EB_ENCAP:
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case DHCP_VENDOR_ENCAP:
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/* Process encapsulated options field */
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if ( ( rc = set_dhcp_packet_encap_options ( dhcppkt,
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options,
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tag )) !=0)
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return rc;
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break;
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default:
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/* Copy option to reassembled packet */
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option = find_dhcp_option ( options, tag );
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if ( ! option )
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break;
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if ( ( rc = set_dhcp_packet_option ( dhcppkt, tag,
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&option->data,
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option->len)) !=0)
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return rc;
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break;
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};
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}
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return 0;
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}
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/**
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* Set options within DHCP packet
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*
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* @v dhcppkt DHCP packet
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* @v options DHCP option block, or NULL
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* @ret rc Return status code
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*
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* Copies options from DHCP options blocks into a DHCP packet. Most
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* options are copied verbatim. Recognised encapsulated options
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* fields are handled as such.
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*
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* @c options may specify a single options block, or be left as NULL
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* in order to copy options from all registered options blocks.
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*/
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static int set_dhcp_packet_options ( struct dhcp_packet *dhcppkt,
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struct dhcp_option_block *options ) {
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return set_dhcp_packet_encap_options ( dhcppkt, options, 0 );
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}
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/**
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* Create a DHCP packet
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*
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* @v dhcp DHCP session
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* @v msgtype DHCP message type
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* @v data Buffer for DHCP packet
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* @v max_len Size of DHCP packet buffer
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* @v dhcppkt DHCP packet structure to fill in
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* @ret rc Return status code
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*
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* Creates a DHCP packet in the specified buffer, and fills out a @c
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* dhcp_packet structure that can be passed to
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* set_dhcp_packet_option() or set_dhcp_packet_options().
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*/
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static int create_dhcp_packet ( struct dhcp_session *dhcp, uint8_t msgtype,
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void *data, size_t max_len,
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struct dhcp_packet *dhcppkt ) {
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struct dhcphdr *dhcphdr = data;
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static const uint8_t overloading = ( DHCP_OPTION_OVERLOAD_FILE |
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DHCP_OPTION_OVERLOAD_SNAME );
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int rc;
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/* Sanity check */
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if ( max_len < sizeof ( *dhcphdr ) )
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return -ENOSPC;
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/* Initialise DHCP packet content */
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memset ( dhcphdr, 0, max_len );
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dhcphdr->xid = dhcp->xid;
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dhcphdr->magic = htonl ( DHCP_MAGIC_COOKIE );
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dhcphdr->htype = ntohs ( dhcp->netdev->ll_protocol->ll_proto );
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dhcphdr->hlen = dhcp->netdev->ll_protocol->ll_addr_len;
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memcpy ( dhcphdr->chaddr, dhcp->netdev->ll_addr, dhcphdr->hlen );
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dhcphdr->op = dhcp_op[msgtype];
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/* Initialise DHCP packet structure */
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dhcppkt->dhcphdr = dhcphdr;
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dhcppkt->max_len = max_len;
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init_dhcp_options ( &dhcppkt->options[OPTS_MAIN], dhcphdr->options,
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( max_len -
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offsetof ( typeof ( *dhcphdr ), options ) ) );
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init_dhcp_options ( &dhcppkt->options[OPTS_FILE], dhcphdr->file,
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sizeof ( dhcphdr->file ) );
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init_dhcp_options ( &dhcppkt->options[OPTS_SNAME], dhcphdr->sname,
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sizeof ( dhcphdr->sname ) );
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/* Set DHCP_OPTION_OVERLOAD option within the main options block */
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if ( set_dhcp_option ( &dhcppkt->options[OPTS_MAIN],
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DHCP_OPTION_OVERLOAD, &overloading,
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sizeof ( overloading ) ) == NULL )
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return -ENOSPC;
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/* Set DHCP_MESSAGE_TYPE option */
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if ( ( rc = set_dhcp_packet_option ( dhcppkt, DHCP_MESSAGE_TYPE,
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&msgtype,
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sizeof ( msgtype ) ) ) != 0 )
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return rc;
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return 0;
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}
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/**
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* Calculate used length of a field containing DHCP options
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*
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* @v data Field containing DHCP options
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* @v max_len Field length
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* @ret len Used length (excluding the @c DHCP_END tag)
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*/
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static size_t dhcp_field_len ( const void *data, size_t max_len ) {
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struct dhcp_option_block options;
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struct dhcp_option *end;
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options.data = ( ( void * ) data );
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options.len = max_len;
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end = find_dhcp_option ( &options, DHCP_END );
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return ( end ? ( ( ( void * ) end ) - data ) : 0 );
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}
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/**
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* Merge field containing DHCP options or string into DHCP options block
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*
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* @v options DHCP option block
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* @v data Field containing DHCP options
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* @v max_len Field length
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* @v tag DHCP option tag, or 0
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*
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* If @c tag is non-zero, the field will be treated as a
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* NUL-terminated string representing the value of the specified DHCP
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* option. If @c tag is zero, the field will be treated as a block of
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* DHCP options, and simply appended to the existing options in the
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* option block.
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*
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* The caller must ensure that there is enough space in the options
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* block to perform the merge.
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*/
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static void merge_dhcp_field ( struct dhcp_option_block *options,
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const void *data, size_t max_len,
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unsigned int tag ) {
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size_t len;
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void *dest;
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struct dhcp_option *end;
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if ( tag ) {
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set_dhcp_option ( options, tag, data, strlen ( data ) );
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} else {
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len = dhcp_field_len ( data, max_len );
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dest = ( options->data + options->len - 1 );
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memcpy ( dest, data, len );
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options->len += len;
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end = ( dest + len );
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end->tag = DHCP_END;
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}
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}
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/**
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* Parse DHCP packet and construct DHCP options block
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*
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* @v dhcphdr DHCP packet
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* @v len Length of DHCP packet
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* @ret options DHCP options block, or NULL
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*
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* Parses a received DHCP packet and canonicalises its contents into a
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* single DHCP options block. The "file" and "sname" fields are
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* converted into the corresponding DHCP options (@c
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* DHCP_BOOTFILE_NAME and @c DHCP_TFTP_SERVER_NAME respectively). If
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* these fields are used for option overloading, their options are
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* merged in to the options block.
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*
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* The values of the "yiaddr" and "siaddr" fields will be stored
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* within the options block as the magic options @c DHCP_EB_YIADDR and
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* @c DHCP_EB_SIADDR.
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*
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* Note that this call allocates new memory for the constructed DHCP
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* options block; it is the responsibility of the caller to eventually
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* free this memory.
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*/
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static struct dhcp_option_block * dhcp_parse ( struct dhcphdr *dhcphdr,
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size_t len ) {
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struct dhcp_option_block *options;
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size_t options_len;
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unsigned int overloading;
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/* Sanity check */
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if ( len < sizeof ( *dhcphdr ) )
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return NULL;
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/* Calculate size of resulting concatenated option block:
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*
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* The "options" field : length of the field minus the DHCP_END tag.
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*
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* The "file" field : maximum length of the field minus the
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* NUL terminator, plus a 2-byte DHCP header or, if used for
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* option overloading, the length of the field minus the
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* DHCP_END tag.
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*
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* The "sname" field : as for the "file" field.
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*
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* 15 bytes for an encapsulated options field to contain the
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* value of the "yiaddr" and "siaddr" fields
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*
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* 1 byte for a final terminating DHCP_END tag.
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*/
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options_len = ( ( len - offsetof ( typeof ( *dhcphdr ), options ) ) - 1
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+ ( sizeof ( dhcphdr->file ) + 1 )
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+ ( sizeof ( dhcphdr->sname ) + 1 )
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+ 15 /* yiaddr and siaddr */
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+ 1 /* DHCP_END tag */ );
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/* Allocate empty options block of required size */
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options = alloc_dhcp_options ( options_len );
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if ( ! options ) {
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DBG ( "DHCP could not allocate %d-byte option block\n",
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options_len );
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return NULL;
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}
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/* Merge in "options" field, if this is a DHCP packet */
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if ( dhcphdr->magic == htonl ( DHCP_MAGIC_COOKIE ) ) {
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merge_dhcp_field ( options, dhcphdr->options,
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( len -
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offsetof ( typeof (*dhcphdr), options ) ),
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0 /* Always contains options */ );
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}
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/* Identify overloaded fields */
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overloading = find_dhcp_num_option ( options, DHCP_OPTION_OVERLOAD );
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/* Merge in "file" and "sname" fields */
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merge_dhcp_field ( options, dhcphdr->file, sizeof ( dhcphdr->file ),
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( ( overloading & DHCP_OPTION_OVERLOAD_FILE ) ?
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DHCP_BOOTFILE_NAME : 0 ) );
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merge_dhcp_field ( options, dhcphdr->sname, sizeof ( dhcphdr->sname ),
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( ( overloading & DHCP_OPTION_OVERLOAD_SNAME ) ?
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DHCP_TFTP_SERVER_NAME : 0 ) );
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/* Set magic options for "yiaddr" and "siaddr", if present */
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if ( dhcphdr->yiaddr.s_addr ) {
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set_dhcp_option ( options, DHCP_EB_YIADDR,
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&dhcphdr->yiaddr, sizeof (dhcphdr->yiaddr) );
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}
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if ( dhcphdr->siaddr.s_addr ) {
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set_dhcp_option ( options, DHCP_EB_SIADDR,
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&dhcphdr->siaddr, sizeof (dhcphdr->siaddr) );
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}
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assert ( options->len <= options->max_len );
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return options;
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}
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/****************************************************************************
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*
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* DHCP to UDP interface
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*
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*/
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static inline struct dhcp_session *
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udp_to_dhcp ( struct udp_connection *conn ) {
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return container_of ( conn, struct dhcp_session, udp );
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}
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/** Address for transmitting DHCP requests */
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static struct sockaddr sa_dhcp_server = {
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.sa_family = AF_INET,
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.sin = {
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.sin_addr.s_addr = INADDR_BROADCAST,
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.sin_port = htons ( BOOTPS_PORT ),
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},
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};
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/**
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* Transmit DHCP request
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*
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* @v conn UDP connection
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* @v buf Temporary data buffer
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* @v len Length of temporary data buffer
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*/
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static void dhcp_senddata ( struct udp_connection *conn,
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void *buf, size_t len ) {
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struct dhcp_session *dhcp = udp_to_dhcp ( conn );
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struct dhcp_packet dhcppkt;
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int rc;
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DBG ( "Transmitting %s\n", dhcp_message_type_name ( dhcp->state ) );
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assert ( ( dhcp->state == DHCPDISCOVER ) ||
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( dhcp->state == DHCPREQUEST ) );
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/* Create DHCP packet in temporary buffer */
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if ( ( rc = create_dhcp_packet ( dhcp, dhcp->state, buf, len,
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&dhcppkt ) ) != 0 ) {
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DBG ( "Could not create DHCP packet\n" );
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return;
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}
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/* Copy in options common to all requests */
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if ( ( rc = set_dhcp_packet_options ( &dhcppkt,
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&dhcp_request_options ) ) != 0 ){
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DBG ( "Could not set common DHCP options\n" );
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return;
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}
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/* Transmit the packet */
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if ( ( rc = udp_sendto ( conn, &sa_dhcp_server,
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dhcppkt.dhcphdr, dhcppkt.len ) ) != 0 ) {
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DBG ( "Could not transmit UDP packet\n" );
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return;
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}
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}
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/**
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* Receive new data
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*
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* @v udp UDP connection
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* @v data Received data
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* @v len Length of received data
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*/
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static void dhcp_newdata ( struct udp_connection *conn,
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void *data, size_t len ) {
|
|
struct dhcp_session *dhcp = udp_to_dhcp ( conn );
|
|
struct dhcphdr *dhcphdr = data;
|
|
struct dhcp_option_block *options;
|
|
|
|
/* Check for matching transaction ID */
|
|
if ( dhcphdr->xid != dhcp->xid ) {
|
|
DBG ( "DHCP wrong transaction ID (wanted %08lx, got %08lx)\n",
|
|
ntohl ( dhcphdr->xid ), ntohl ( dhcp->xid ) );
|
|
return;
|
|
};
|
|
|
|
/* Parse packet and create options structure */
|
|
options = dhcp_parse ( dhcphdr, len );
|
|
if ( ! options ) {
|
|
DBG ( "Could not parse DHCP packet\n" );
|
|
return;
|
|
}
|
|
|
|
DBG ( "Received %s\n",
|
|
dhcp_message_type_name ( find_dhcp_num_option ( options,
|
|
DHCP_MESSAGE_TYPE ) ) );
|
|
|
|
/* Proof of concept: just dump out the parsed options */
|
|
hex_dump ( options->data, options->len );
|
|
free_dhcp_options ( options );
|
|
}
|
|
|
|
/** DHCP UDP operations */
|
|
static struct udp_operations dhcp_udp_operations = {
|
|
.senddata = dhcp_senddata,
|
|
.newdata = dhcp_newdata,
|
|
};
|
|
|
|
/**
|
|
* Initiate DHCP on a network interface
|
|
*
|
|
* @v dhcp DHCP session
|
|
* @ret aop Asynchronous operation
|
|
*/
|
|
struct async_operation * start_dhcp ( struct dhcp_session *dhcp ) {
|
|
int rc;
|
|
|
|
dhcp->udp.udp_op = &dhcp_udp_operations;
|
|
dhcp->state = DHCPDISCOVER;
|
|
/* Use least significant 32 bits of link-layer address as XID */
|
|
memcpy ( &dhcp->xid, ( dhcp->netdev->ll_addr
|
|
+ dhcp->netdev->ll_protocol->ll_addr_len
|
|
- sizeof ( dhcp->xid ) ), sizeof ( dhcp->xid ));
|
|
|
|
/* Bind to local port */
|
|
if ( ( rc = udp_open ( &dhcp->udp, htons ( BOOTPC_PORT ) ) ) != 0 ) {
|
|
async_done ( &dhcp->aop, rc );
|
|
goto out;
|
|
}
|
|
|
|
/* Proof of concept: just send a single DHCPDISCOVER */
|
|
udp_senddata ( &dhcp->udp );
|
|
|
|
out:
|
|
return &dhcp->aop;
|
|
}
|