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dhcp.c
1445 lines (1279 loc) · 40 KB
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dhcp.c
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/*
* Copyright (C) 2006 Michael Brown <mbrown@fensystems.co.uk>.
*
* 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.
*/
FILE_LICENCE ( GPL2_OR_LATER );
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <ctype.h>
#include <errno.h>
#include <assert.h>
#include <byteswap.h>
#include <gpxe/if_ether.h>
#include <gpxe/netdevice.h>
#include <gpxe/device.h>
#include <gpxe/xfer.h>
#include <gpxe/open.h>
#include <gpxe/job.h>
#include <gpxe/retry.h>
#include <gpxe/tcpip.h>
#include <gpxe/ip.h>
#include <gpxe/uuid.h>
#include <gpxe/timer.h>
#include <gpxe/settings.h>
#include <gpxe/dhcp.h>
#include <gpxe/dhcpopts.h>
#include <gpxe/dhcppkt.h>
#include <gpxe/features.h>
/** @file
*
* Dynamic Host Configuration Protocol
*
*/
struct dhcp_session;
static int dhcp_tx ( struct dhcp_session *dhcp );
/**
* DHCP operation types
*
* This table maps from DHCP message types (i.e. values of the @c
* DHCP_MESSAGE_TYPE option) to values of the "op" field within a DHCP
* packet.
*/
static const uint8_t dhcp_op[] = {
[DHCPDISCOVER] = BOOTP_REQUEST,
[DHCPOFFER] = BOOTP_REPLY,
[DHCPREQUEST] = BOOTP_REQUEST,
[DHCPDECLINE] = BOOTP_REQUEST,
[DHCPACK] = BOOTP_REPLY,
[DHCPNAK] = BOOTP_REPLY,
[DHCPRELEASE] = BOOTP_REQUEST,
[DHCPINFORM] = BOOTP_REQUEST,
};
/** Raw option data for options common to all DHCP requests */
static uint8_t dhcp_request_options_data[] = {
DHCP_MESSAGE_TYPE, DHCP_BYTE ( 0 ),
DHCP_MAX_MESSAGE_SIZE,
DHCP_WORD ( ETH_MAX_MTU - 20 /* IP header */ - 8 /* UDP header */ ),
DHCP_CLIENT_ARCHITECTURE, DHCP_WORD ( 0 ),
DHCP_CLIENT_NDI, DHCP_OPTION ( 1 /* UNDI */ , 2, 1 /* v2.1 */ ),
DHCP_VENDOR_CLASS_ID,
DHCP_STRING ( 'P', 'X', 'E', 'C', 'l', 'i', 'e', 'n', 't', ':',
'A', 'r', 'c', 'h', ':', '0', '0', '0', '0', '0', ':',
'U', 'N', 'D', 'I', ':', '0', '0', '2', '0', '0', '1' ),
DHCP_USER_CLASS_ID,
DHCP_STRING ( 'g', 'P', 'X', 'E' ),
DHCP_PARAMETER_REQUEST_LIST,
DHCP_OPTION ( DHCP_SUBNET_MASK, DHCP_ROUTERS, DHCP_DNS_SERVERS,
DHCP_LOG_SERVERS, DHCP_HOST_NAME, DHCP_DOMAIN_NAME,
DHCP_ROOT_PATH, DHCP_VENDOR_ENCAP, DHCP_VENDOR_CLASS_ID,
DHCP_TFTP_SERVER_NAME, DHCP_BOOTFILE_NAME,
DHCP_EB_ENCAP, DHCP_ISCSI_INITIATOR_IQN ),
DHCP_END
};
/** Version number feature */
FEATURE_VERSION ( VERSION_MAJOR, VERSION_MINOR, VERSION_PATCH );
/** DHCP server address setting */
struct setting dhcp_server_setting __setting = {
.name = "dhcp-server",
.description = "DHCP server address",
.tag = DHCP_SERVER_IDENTIFIER,
.type = &setting_type_ipv4,
};
/** DHCP user class setting */
struct setting user_class_setting __setting = {
.name = "user-class",
.description = "User class identifier",
.tag = DHCP_USER_CLASS_ID,
.type = &setting_type_string,
};
/** Use cached network settings */
struct setting use_cached_setting __setting = {
.name = "use-cached",
.description = "Use cached network settings",
.tag = DHCP_EB_USE_CACHED,
.type = &setting_type_uint8,
};
/**
* Name a DHCP packet type
*
* @v msgtype DHCP message type
* @ret string DHCP mesasge type name
*/
static inline const char * dhcp_msgtype_name ( unsigned int msgtype ) {
switch ( msgtype ) {
case DHCPNONE: return "BOOTP"; /* Non-DHCP packet */
case DHCPDISCOVER: return "DHCPDISCOVER";
case DHCPOFFER: return "DHCPOFFER";
case DHCPREQUEST: return "DHCPREQUEST";
case DHCPDECLINE: return "DHCPDECLINE";
case DHCPACK: return "DHCPACK";
case DHCPNAK: return "DHCPNAK";
case DHCPRELEASE: return "DHCPRELEASE";
case DHCPINFORM: return "DHCPINFORM";
default: return "DHCP<invalid>";
}
}
/**
* Calculate DHCP transaction ID for a network device
*
* @v netdev Network device
* @ret xid DHCP XID
*
* Extract the least significant bits of the hardware address for use
* as the transaction ID.
*/
static uint32_t dhcp_xid ( struct net_device *netdev ) {
uint32_t xid;
memcpy ( &xid, ( netdev->ll_addr + netdev->ll_protocol->ll_addr_len
- sizeof ( xid ) ), sizeof ( xid ) );
return xid;
}
/****************************************************************************
*
* DHCP session
*
*/
struct dhcp_session;
/** DHCP session state operations */
struct dhcp_session_state {
/** State name */
const char *name;
/**
* Construct transmitted packet
*
* @v dhcp DHCP session
* @v dhcppkt DHCP packet
* @v peer Destination address
*/
int ( * tx ) ( struct dhcp_session *dhcp,
struct dhcp_packet *dhcppkt,
struct sockaddr_in *peer );
/** Handle received packet
*
* @v dhcp DHCP session
* @v dhcppkt DHCP packet
* @v peer DHCP server address
* @v msgtype DHCP message type
* @v server_id DHCP server ID
*/
void ( * rx ) ( struct dhcp_session *dhcp,
struct dhcp_packet *dhcppkt,
struct sockaddr_in *peer,
uint8_t msgtype, struct in_addr server_id );
/** Handle timer expiry
*
* @v dhcp DHCP session
*/
void ( * expired ) ( struct dhcp_session *dhcp );
/** Transmitted message type */
uint8_t tx_msgtype;
/** Apply minimum timeout */
uint8_t apply_min_timeout;
};
static struct dhcp_session_state dhcp_state_discover;
static struct dhcp_session_state dhcp_state_request;
static struct dhcp_session_state dhcp_state_proxy;
static struct dhcp_session_state dhcp_state_pxebs;
/** A DHCP session */
struct dhcp_session {
/** Reference counter */
struct refcnt refcnt;
/** Job control interface */
struct job_interface job;
/** Data transfer interface */
struct xfer_interface xfer;
/** Network device being configured */
struct net_device *netdev;
/** Local socket address */
struct sockaddr_in local;
/** State of the session */
struct dhcp_session_state *state;
/** Offered IP address */
struct in_addr offer;
/** DHCP server */
struct in_addr server;
/** DHCP offer priority */
int priority;
/** ProxyDHCP protocol extensions should be ignored */
int no_pxedhcp;
/** ProxyDHCP server */
struct in_addr proxy_server;
/** ProxyDHCP port */
uint16_t proxy_port;
/** ProxyDHCP server priority */
int proxy_priority;
/** PXE Boot Server type */
uint16_t pxe_type;
/** List of PXE Boot Servers to attempt */
struct in_addr *pxe_attempt;
/** List of PXE Boot Servers to accept */
struct in_addr *pxe_accept;
/** Retransmission timer */
struct retry_timer timer;
/** Start time of the current state (in ticks) */
unsigned long start;
};
/**
* Free DHCP session
*
* @v refcnt Reference counter
*/
static void dhcp_free ( struct refcnt *refcnt ) {
struct dhcp_session *dhcp =
container_of ( refcnt, struct dhcp_session, refcnt );
netdev_put ( dhcp->netdev );
free ( dhcp );
}
/**
* Mark DHCP session as complete
*
* @v dhcp DHCP session
* @v rc Return status code
*/
static void dhcp_finished ( struct dhcp_session *dhcp, int rc ) {
/* Block futher incoming messages */
job_nullify ( &dhcp->job );
xfer_nullify ( &dhcp->xfer );
/* Stop retry timer */
stop_timer ( &dhcp->timer );
/* Free resources and close interfaces */
xfer_close ( &dhcp->xfer, rc );
job_done ( &dhcp->job, rc );
}
/**
* Transition to new DHCP session state
*
* @v dhcp DHCP session
* @v state New session state
*/
static void dhcp_set_state ( struct dhcp_session *dhcp,
struct dhcp_session_state *state ) {
DBGC ( dhcp, "DHCP %p entering %s state\n", dhcp, state->name );
dhcp->state = state;
dhcp->start = currticks();
stop_timer ( &dhcp->timer );
dhcp->timer.min_timeout =
( state->apply_min_timeout ? DHCP_MIN_TIMEOUT : 0 );
dhcp->timer.max_timeout = DHCP_MAX_TIMEOUT;
start_timer_nodelay ( &dhcp->timer );
}
/****************************************************************************
*
* DHCP state machine
*
*/
/**
* Construct transmitted packet for DHCP discovery
*
* @v dhcp DHCP session
* @v dhcppkt DHCP packet
* @v peer Destination address
*/
static int dhcp_discovery_tx ( struct dhcp_session *dhcp,
struct dhcp_packet *dhcppkt __unused,
struct sockaddr_in *peer ) {
DBGC ( dhcp, "DHCP %p DHCPDISCOVER\n", dhcp );
/* Set server address */
peer->sin_addr.s_addr = INADDR_BROADCAST;
peer->sin_port = htons ( BOOTPS_PORT );
return 0;
}
/**
* Handle received packet during DHCP discovery
*
* @v dhcp DHCP session
* @v dhcppkt DHCP packet
* @v peer DHCP server address
* @v msgtype DHCP message type
* @v server_id DHCP server ID
*/
static void dhcp_discovery_rx ( struct dhcp_session *dhcp,
struct dhcp_packet *dhcppkt,
struct sockaddr_in *peer, uint8_t msgtype,
struct in_addr server_id ) {
struct in_addr ip;
char vci[9]; /* "PXEClient" */
int vci_len;
int has_pxeclient;
int pxeopts_len;
int has_pxeopts;
int8_t priority = 0;
uint8_t no_pxedhcp = 0;
unsigned long elapsed;
DBGC ( dhcp, "DHCP %p %s from %s:%d", dhcp,
dhcp_msgtype_name ( msgtype ), inet_ntoa ( peer->sin_addr ),
ntohs ( peer->sin_port ) );
if ( server_id.s_addr != peer->sin_addr.s_addr )
DBGC ( dhcp, " (%s)", inet_ntoa ( server_id ) );
/* Identify offered IP address */
ip = dhcppkt->dhcphdr->yiaddr;
if ( ip.s_addr )
DBGC ( dhcp, " for %s", inet_ntoa ( ip ) );
/* Identify "PXEClient" vendor class */
vci_len = dhcppkt_fetch ( dhcppkt, DHCP_VENDOR_CLASS_ID,
vci, sizeof ( vci ) );
has_pxeclient = ( ( vci_len >= ( int ) sizeof ( vci ) ) &&
( strncmp ( "PXEClient", vci, sizeof (vci) ) == 0 ));
/* Identify presence of PXE-specific options */
pxeopts_len = dhcppkt_fetch ( dhcppkt, DHCP_PXE_BOOT_MENU, NULL, 0 );
has_pxeopts = ( pxeopts_len >= 0 );
if ( has_pxeclient )
DBGC ( dhcp, "%s", ( has_pxeopts ? " pxe" : " proxy" ) );
/* Identify priority */
dhcppkt_fetch ( dhcppkt, DHCP_EB_PRIORITY, &priority,
sizeof ( priority ) );
if ( priority )
DBGC ( dhcp, " pri %d", priority );
/* Identify ignore-PXE flag */
dhcppkt_fetch ( dhcppkt, DHCP_EB_NO_PXEDHCP, &no_pxedhcp,
sizeof ( no_pxedhcp ) );
if ( no_pxedhcp )
DBGC ( dhcp, " nopxe" );
DBGC ( dhcp, "\n" );
/* Select as DHCP offer, if applicable */
if ( ip.s_addr && ( peer->sin_port == htons ( BOOTPS_PORT ) ) &&
( ( msgtype == DHCPOFFER ) || ( ! msgtype /* BOOTP */ ) ) &&
( priority >= dhcp->priority ) ) {
dhcp->offer = ip;
dhcp->server = server_id;
dhcp->priority = priority;
dhcp->no_pxedhcp = no_pxedhcp;
}
/* Select as ProxyDHCP offer, if applicable */
if ( has_pxeclient && ( msgtype == DHCPOFFER ) &&
( priority >= dhcp->proxy_priority ) ) {
/* If the offer already includes the PXE options, then
* assume that we can send the ProxyDHCPREQUEST to
* port 67 (since the DHCPDISCOVER that triggered this
* ProxyDHCPOFFER was sent to port 67). Otherwise,
* send the ProxyDHCPREQUEST to port 4011.
*/
dhcp->proxy_server = server_id;
dhcp->proxy_port = ( has_pxeopts ? htons ( BOOTPS_PORT )
: htons ( PXE_PORT ) );
dhcp->proxy_priority = priority;
}
/* We can exit the discovery state when we have a valid
* DHCPOFFER, and either:
*
* o The DHCPOFFER instructs us to ignore ProxyDHCPOFFERs, or
* o We have a valid ProxyDHCPOFFER, or
* o We have allowed sufficient time for ProxyDHCPOFFERs.
*/
/* If we don't yet have a DHCPOFFER, do nothing */
if ( ! dhcp->offer.s_addr )
return;
/* If we can't yet transition to DHCPREQUEST, do nothing */
elapsed = ( currticks() - dhcp->start );
if ( ! ( dhcp->no_pxedhcp || dhcp->proxy_server.s_addr ||
( elapsed > PROXYDHCP_MAX_TIMEOUT ) ) )
return;
/* Transition to DHCPREQUEST */
dhcp_set_state ( dhcp, &dhcp_state_request );
}
/**
* Handle timer expiry during DHCP discovery
*
* @v dhcp DHCP session
*/
static void dhcp_discovery_expired ( struct dhcp_session *dhcp ) {
unsigned long elapsed = ( currticks() - dhcp->start );
/* Give up waiting for ProxyDHCP before we reach the failure point */
if ( dhcp->offer.s_addr && ( elapsed > PROXYDHCP_MAX_TIMEOUT ) ) {
dhcp_set_state ( dhcp, &dhcp_state_request );
return;
}
/* Otherwise, retransmit current packet */
dhcp_tx ( dhcp );
}
/** DHCP discovery state operations */
static struct dhcp_session_state dhcp_state_discover = {
.name = "discovery",
.tx = dhcp_discovery_tx,
.rx = dhcp_discovery_rx,
.expired = dhcp_discovery_expired,
.tx_msgtype = DHCPDISCOVER,
.apply_min_timeout = 1,
};
/**
* Construct transmitted packet for DHCP request
*
* @v dhcp DHCP session
* @v dhcppkt DHCP packet
* @v peer Destination address
*/
static int dhcp_request_tx ( struct dhcp_session *dhcp,
struct dhcp_packet *dhcppkt,
struct sockaddr_in *peer ) {
int rc;
DBGC ( dhcp, "DHCP %p DHCPREQUEST to %s:%d",
dhcp, inet_ntoa ( dhcp->server ), BOOTPS_PORT );
DBGC ( dhcp, " for %s\n", inet_ntoa ( dhcp->offer ) );
/* Set server ID */
if ( ( rc = dhcppkt_store ( dhcppkt, DHCP_SERVER_IDENTIFIER,
&dhcp->server,
sizeof ( dhcp->server ) ) ) != 0 )
return rc;
/* Set requested IP address */
if ( ( rc = dhcppkt_store ( dhcppkt, DHCP_REQUESTED_ADDRESS,
&dhcp->offer,
sizeof ( dhcp->offer ) ) ) != 0 )
return rc;
/* Set server address */
peer->sin_addr.s_addr = INADDR_BROADCAST;
peer->sin_port = htons ( BOOTPS_PORT );
return 0;
}
/**
* Handle received packet during DHCP request
*
* @v dhcp DHCP session
* @v dhcppkt DHCP packet
* @v peer DHCP server address
* @v msgtype DHCP message type
* @v server_id DHCP server ID
*/
static void dhcp_request_rx ( struct dhcp_session *dhcp,
struct dhcp_packet *dhcppkt,
struct sockaddr_in *peer, uint8_t msgtype,
struct in_addr server_id ) {
struct in_addr ip;
struct settings *parent;
int rc;
DBGC ( dhcp, "DHCP %p %s from %s:%d", dhcp,
dhcp_msgtype_name ( msgtype ), inet_ntoa ( peer->sin_addr ),
ntohs ( peer->sin_port ) );
if ( server_id.s_addr != peer->sin_addr.s_addr )
DBGC ( dhcp, " (%s)", inet_ntoa ( server_id ) );
/* Identify leased IP address */
ip = dhcppkt->dhcphdr->yiaddr;
if ( ip.s_addr )
DBGC ( dhcp, " for %s", inet_ntoa ( ip ) );
DBGC ( dhcp, "\n" );
/* Filter out unacceptable responses */
if ( peer->sin_port != htons ( BOOTPS_PORT ) )
return;
if ( msgtype /* BOOTP */ && ( msgtype != DHCPACK ) )
return;
if ( server_id.s_addr != dhcp->server.s_addr )
return;
/* Record assigned address */
dhcp->local.sin_addr = ip;
/* Register settings */
parent = netdev_settings ( dhcp->netdev );
if ( ( rc = register_settings ( &dhcppkt->settings, parent ) ) != 0 ){
DBGC ( dhcp, "DHCP %p could not register settings: %s\n",
dhcp, strerror ( rc ) );
dhcp_finished ( dhcp, rc );
return;
}
/* Start ProxyDHCPREQUEST if applicable */
if ( dhcp->proxy_server.s_addr /* Have ProxyDHCP server */ &&
( ! dhcp->no_pxedhcp ) /* ProxyDHCP not disabled */ &&
( /* ProxyDHCP server is not just the DHCP server itself */
( dhcp->proxy_server.s_addr != dhcp->server.s_addr ) ||
( dhcp->proxy_port != htons ( BOOTPS_PORT ) ) ) ) {
dhcp_set_state ( dhcp, &dhcp_state_proxy );
return;
}
/* Terminate DHCP */
dhcp_finished ( dhcp, 0 );
}
/**
* Handle timer expiry during DHCP discovery
*
* @v dhcp DHCP session
*/
static void dhcp_request_expired ( struct dhcp_session *dhcp ) {
/* Retransmit current packet */
dhcp_tx ( dhcp );
}
/** DHCP request state operations */
static struct dhcp_session_state dhcp_state_request = {
.name = "request",
.tx = dhcp_request_tx,
.rx = dhcp_request_rx,
.expired = dhcp_request_expired,
.tx_msgtype = DHCPREQUEST,
.apply_min_timeout = 0,
};
/**
* Construct transmitted packet for ProxyDHCP request
*
* @v dhcp DHCP session
* @v dhcppkt DHCP packet
* @v peer Destination address
*/
static int dhcp_proxy_tx ( struct dhcp_session *dhcp,
struct dhcp_packet *dhcppkt,
struct sockaddr_in *peer ) {
int rc;
DBGC ( dhcp, "DHCP %p ProxyDHCP REQUEST to %s:%d\n", dhcp,
inet_ntoa ( dhcp->proxy_server ), ntohs ( dhcp->proxy_port ) );
/* Set server ID */
if ( ( rc = dhcppkt_store ( dhcppkt, DHCP_SERVER_IDENTIFIER,
&dhcp->proxy_server,
sizeof ( dhcp->proxy_server ) ) ) != 0 )
return rc;
/* Set server address */
peer->sin_addr = dhcp->proxy_server;
peer->sin_port = dhcp->proxy_port;
return 0;
}
/**
* Handle received packet during ProxyDHCP request
*
* @v dhcp DHCP session
* @v dhcppkt DHCP packet
* @v peer DHCP server address
* @v msgtype DHCP message type
* @v server_id DHCP server ID
*/
static void dhcp_proxy_rx ( struct dhcp_session *dhcp,
struct dhcp_packet *dhcppkt,
struct sockaddr_in *peer, uint8_t msgtype,
struct in_addr server_id ) {
int rc;
DBGC ( dhcp, "DHCP %p %s from %s:%d", dhcp,
dhcp_msgtype_name ( msgtype ), inet_ntoa ( peer->sin_addr ),
ntohs ( peer->sin_port ) );
if ( server_id.s_addr != peer->sin_addr.s_addr )
DBGC ( dhcp, " (%s)", inet_ntoa ( server_id ) );
DBGC ( dhcp, "\n" );
/* Filter out unacceptable responses */
if ( peer->sin_port != dhcp->proxy_port )
return;
if ( ( msgtype != DHCPOFFER ) && ( msgtype != DHCPACK ) )
return;
if ( server_id.s_addr /* Linux PXE server omits server ID */ &&
( server_id.s_addr != dhcp->proxy_server.s_addr ) )
return;
/* Register settings */
dhcppkt->settings.name = PROXYDHCP_SETTINGS_NAME;
if ( ( rc = register_settings ( &dhcppkt->settings, NULL ) ) != 0 ) {
DBGC ( dhcp, "DHCP %p could not register settings: %s\n",
dhcp, strerror ( rc ) );
dhcp_finished ( dhcp, rc );
return;
}
/* Terminate DHCP */
dhcp_finished ( dhcp, 0 );
}
/**
* Handle timer expiry during ProxyDHCP request
*
* @v dhcp DHCP session
*/
static void dhcp_proxy_expired ( struct dhcp_session *dhcp ) {
unsigned long elapsed = ( currticks() - dhcp->start );
/* Give up waiting for ProxyDHCP before we reach the failure point */
if ( elapsed > PROXYDHCP_MAX_TIMEOUT ) {
dhcp_finished ( dhcp, 0 );
return;
}
/* Retransmit current packet */
dhcp_tx ( dhcp );
}
/** ProxyDHCP request state operations */
static struct dhcp_session_state dhcp_state_proxy = {
.name = "ProxyDHCP",
.tx = dhcp_proxy_tx,
.rx = dhcp_proxy_rx,
.expired = dhcp_proxy_expired,
.tx_msgtype = DHCPREQUEST,
.apply_min_timeout = 0,
};
/**
* Construct transmitted packet for PXE Boot Server Discovery
*
* @v dhcp DHCP session
* @v dhcppkt DHCP packet
* @v peer Destination address
*/
static int dhcp_pxebs_tx ( struct dhcp_session *dhcp,
struct dhcp_packet *dhcppkt,
struct sockaddr_in *peer ) {
struct dhcp_pxe_boot_menu_item menu_item = { 0, 0 };
int rc;
/* Set server address */
peer->sin_addr = *(dhcp->pxe_attempt);
peer->sin_port = ( ( peer->sin_addr.s_addr == INADDR_BROADCAST ) ?
htons ( BOOTPS_PORT ) : htons ( PXE_PORT ) );
DBGC ( dhcp, "DHCP %p PXEBS REQUEST to %s:%d for type %d\n",
dhcp, inet_ntoa ( peer->sin_addr ), ntohs ( peer->sin_port ),
le16_to_cpu ( dhcp->pxe_type ) );
/* Set boot menu item */
menu_item.type = dhcp->pxe_type;
if ( ( rc = dhcppkt_store ( dhcppkt, DHCP_PXE_BOOT_MENU_ITEM,
&menu_item, sizeof ( menu_item ) ) ) != 0 )
return rc;
return 0;
}
/**
* Check to see if PXE Boot Server address is acceptable
*
* @v dhcp DHCP session
* @v bs Boot Server address
* @ret accept Boot Server is acceptable
*/
static int dhcp_pxebs_accept ( struct dhcp_session *dhcp,
struct in_addr bs ) {
struct in_addr *accept;
/* Accept if we have no acceptance filter */
if ( ! dhcp->pxe_accept )
return 1;
/* Scan through acceptance list */
for ( accept = dhcp->pxe_accept ; accept->s_addr ; accept++ ) {
if ( accept->s_addr == bs.s_addr )
return 1;
}
DBGC ( dhcp, "DHCP %p rejecting server %s\n",
dhcp, inet_ntoa ( bs ) );
return 0;
}
/**
* Handle received packet during PXE Boot Server Discovery
*
* @v dhcp DHCP session
* @v dhcppkt DHCP packet
* @v peer DHCP server address
* @v msgtype DHCP message type
* @v server_id DHCP server ID
*/
static void dhcp_pxebs_rx ( struct dhcp_session *dhcp,
struct dhcp_packet *dhcppkt,
struct sockaddr_in *peer, uint8_t msgtype,
struct in_addr server_id ) {
struct dhcp_pxe_boot_menu_item menu_item = { 0, 0 };
int rc;
DBGC ( dhcp, "DHCP %p %s from %s:%d", dhcp,
dhcp_msgtype_name ( msgtype ), inet_ntoa ( peer->sin_addr ),
ntohs ( peer->sin_port ) );
if ( server_id.s_addr != peer->sin_addr.s_addr )
DBGC ( dhcp, " (%s)", inet_ntoa ( server_id ) );
/* Identify boot menu item */
dhcppkt_fetch ( dhcppkt, DHCP_PXE_BOOT_MENU_ITEM,
&menu_item, sizeof ( menu_item ) );
if ( menu_item.type )
DBGC ( dhcp, " for type %d", ntohs ( menu_item.type ) );
DBGC ( dhcp, "\n" );
/* Filter out unacceptable responses */
if ( ( peer->sin_port != htons ( BOOTPS_PORT ) ) &&
( peer->sin_port != htons ( PXE_PORT ) ) )
return;
if ( msgtype != DHCPACK )
return;
if ( menu_item.type != dhcp->pxe_type )
return;
if ( ! dhcp_pxebs_accept ( dhcp, ( server_id.s_addr ?
server_id : peer->sin_addr ) ) )
return;
/* Register settings */
dhcppkt->settings.name = PXEBS_SETTINGS_NAME;
if ( ( rc = register_settings ( &dhcppkt->settings, NULL ) ) != 0 ) {
DBGC ( dhcp, "DHCP %p could not register settings: %s\n",
dhcp, strerror ( rc ) );
dhcp_finished ( dhcp, rc );
return;
}
/* Terminate DHCP */
dhcp_finished ( dhcp, 0 );
}
/**
* Handle timer expiry during PXE Boot Server Discovery
*
* @v dhcp DHCP session
*/
static void dhcp_pxebs_expired ( struct dhcp_session *dhcp ) {
unsigned long elapsed = ( currticks() - dhcp->start );
/* Give up waiting before we reach the failure point, and fail
* over to the next server in the attempt list
*/
if ( elapsed > PXEBS_MAX_TIMEOUT ) {
dhcp->pxe_attempt++;
if ( dhcp->pxe_attempt->s_addr ) {
dhcp_set_state ( dhcp, &dhcp_state_pxebs );
return;
} else {
dhcp_finished ( dhcp, -ETIMEDOUT );
return;
}
}
/* Retransmit current packet */
dhcp_tx ( dhcp );
}
/** PXE Boot Server Discovery state operations */
static struct dhcp_session_state dhcp_state_pxebs = {
.name = "PXEBS",
.tx = dhcp_pxebs_tx,
.rx = dhcp_pxebs_rx,
.expired = dhcp_pxebs_expired,
.tx_msgtype = DHCPREQUEST,
.apply_min_timeout = 1,
};
/****************************************************************************
*
* Packet construction
*
*/
/**
* Construct DHCP client hardware address field and broadcast flag
*
* @v netdev Network device
* @v hlen DHCP hardware address length to fill in
* @v flags DHCP flags to fill in
* @ret chaddr DHCP client hardware address
*/
void * dhcp_chaddr ( struct net_device *netdev, uint8_t *hlen,
uint16_t *flags ) {
struct ll_protocol *ll_protocol = netdev->ll_protocol;
typeof ( ( ( struct dhcphdr * ) NULL )->chaddr ) chaddr;
/* If the link-layer address cannot fit into the chaddr field
* (as is the case for IPoIB) then try using the hardware
* address instead. If we do this, set the broadcast flag,
* since chaddr then does not represent a valid link-layer
* address for the return path.
*
* If even the hardware address is too large, use an empty
* chaddr field and set the broadcast flag.
*
* This goes against RFC4390, but RFC4390 mandates that we use
* a DHCP client identifier that conforms with RFC4361, which
* we cannot do without either persistent (NIC-independent)
* storage, or by eliminating the hardware address completely
* from the DHCP packet, which seems unfriendly to users.
*/
if ( ( *hlen = ll_protocol->ll_addr_len ) <= sizeof ( chaddr ) ) {
return netdev->ll_addr;
}
*flags = htons ( BOOTP_FL_BROADCAST );
if ( ( *hlen = ll_protocol->hw_addr_len ) <= sizeof ( chaddr ) ) {
return netdev->hw_addr;
} else {
*hlen = 0;
return NULL;
}
}
/**
* Create a DHCP packet
*
* @v dhcppkt DHCP packet structure to fill in
* @v netdev Network device
* @v msgtype DHCP message type
* @v options Initial options to include (or NULL)
* @v options_len Length of initial options
* @v data Buffer for DHCP packet
* @v max_len Size of DHCP packet buffer
* @ret rc Return status code
*
* Creates a DHCP packet in the specified buffer, and initialise a
* DHCP packet structure.
*/
int dhcp_create_packet ( struct dhcp_packet *dhcppkt,
struct net_device *netdev, uint8_t msgtype,
const void *options, size_t options_len,
void *data, size_t max_len ) {
struct dhcphdr *dhcphdr = data;
void *chaddr;
int rc;
/* Sanity check */
if ( max_len < ( sizeof ( *dhcphdr ) + options_len ) )
return -ENOSPC;
/* Initialise DHCP packet content */
memset ( dhcphdr, 0, max_len );
dhcphdr->xid = dhcp_xid ( netdev );
dhcphdr->magic = htonl ( DHCP_MAGIC_COOKIE );
dhcphdr->htype = ntohs ( netdev->ll_protocol->ll_proto );
dhcphdr->op = dhcp_op[msgtype];
chaddr = dhcp_chaddr ( netdev, &dhcphdr->hlen, &dhcphdr->flags );
memcpy ( dhcphdr->chaddr, chaddr, dhcphdr->hlen );
memcpy ( dhcphdr->options, options, options_len );
/* Initialise DHCP packet structure */
memset ( dhcppkt, 0, sizeof ( *dhcppkt ) );
dhcppkt_init ( dhcppkt, data, max_len );
/* Set DHCP_MESSAGE_TYPE option */
if ( ( rc = dhcppkt_store ( dhcppkt, DHCP_MESSAGE_TYPE,
&msgtype, sizeof ( msgtype ) ) ) != 0 )
return rc;
return 0;
}
/**
* Create DHCP request packet
*
* @v dhcppkt DHCP packet structure to fill in
* @v netdev Network device
* @v msgtype DHCP message type
* @v ciaddr Client IP address
* @v data Buffer for DHCP packet
* @v max_len Size of DHCP packet buffer
* @ret rc Return status code
*
* Creates a DHCP request packet in the specified buffer, and
* initialise a DHCP packet structure.
*/
int dhcp_create_request ( struct dhcp_packet *dhcppkt,
struct net_device *netdev, unsigned int msgtype,
struct in_addr ciaddr, void *data, size_t max_len ) {
struct dhcp_netdev_desc dhcp_desc;
struct dhcp_client_id client_id;
struct dhcp_client_uuid client_uuid;
uint8_t *dhcp_features;
size_t dhcp_features_len;
size_t ll_addr_len;
ssize_t len;
int rc;
/* Create DHCP packet */
if ( ( rc = dhcp_create_packet ( dhcppkt, netdev, msgtype,
dhcp_request_options_data,
sizeof ( dhcp_request_options_data ),
data, max_len ) ) != 0 ) {
DBG ( "DHCP could not create DHCP packet: %s\n",
strerror ( rc ) );
return rc;
}
/* Set client IP address */
dhcppkt->dhcphdr->ciaddr = ciaddr;
/* Add options to identify the feature list */
dhcp_features = table_start ( DHCP_FEATURES );
dhcp_features_len = table_num_entries ( DHCP_FEATURES );
if ( ( rc = dhcppkt_store ( dhcppkt, DHCP_EB_ENCAP, dhcp_features,
dhcp_features_len ) ) != 0 ) {
DBG ( "DHCP could not set features list option: %s\n",
strerror ( rc ) );
return rc;
}
/* Add options to identify the network device */
fetch_setting ( &netdev->settings.settings, &busid_setting, &dhcp_desc,
sizeof ( dhcp_desc ) );
if ( ( rc = dhcppkt_store ( dhcppkt, DHCP_EB_BUS_ID, &dhcp_desc,
sizeof ( dhcp_desc ) ) ) != 0 ) {
DBG ( "DHCP could not set bus ID option: %s\n",
strerror ( rc ) );
return rc;
}
/* Add DHCP client identifier. Required for Infiniband, and
* doesn't hurt other link layers.
*/
client_id.ll_proto = ntohs ( netdev->ll_protocol->ll_proto );
ll_addr_len = netdev->ll_protocol->ll_addr_len;
assert ( ll_addr_len <= sizeof ( client_id.ll_addr ) );
memcpy ( client_id.ll_addr, netdev->ll_addr, ll_addr_len );
if ( ( rc = dhcppkt_store ( dhcppkt, DHCP_CLIENT_ID, &client_id,
( ll_addr_len + 1 ) ) ) != 0 ) {
DBG ( "DHCP could not set client ID: %s\n",
strerror ( rc ) );
return rc;
}
/* Add client UUID, if we have one. Required for PXE. */