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/* UnrecoverableKeyException.java -- Cannot recover a key from the key store
   Copyright (C) 1998, 2002 Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath 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, or (at your option)
any later version.

GNU Classpath 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 GNU Classpath; see the file COPYING.  If not, write to the
Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA.

Linking this library statically or dynamically with other modules is
making a combined work based on this library.  Thus, the terms and
conditions of the GNU General Public License cover the whole
combination.

As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
modules, and to copy and distribute the resulting executable under
terms of your choice, provided that you also meet, for each linked
independent module, the terms and conditions of the license of that
module.  An independent module is a module which is not derived from
or based on this library.  If you modify this library, you may extend
this exception to your version of the library, but you are not
obligated to do so.  If you do not wish to do so, delete this
exception statement from your version. */

package java.security;

/**
 * This exception is thrown when a key cannot be recovered from the key
 * store.
 *
 * @author Aaron M. Renn <arenn@urbanophile.com>
 * @since 1.2
 * @status updated to 1.4
 */
public class UnrecoverableKeyException extends GeneralSecurityException
{
  /**
   * Compatible with JDK 1.2+.
   */
  private static final long serialVersionUID = 7275063078190151277L;

  /**
   * Create an instance with no descriptive error message.
   */
  public UnrecoverableKeyException()
  {
  }

  /**
   * Create an instance with a descriptive error message.
   *
   * @param msg the descriptive error message
   */
  public UnrecoverableKeyException(String msg)
  {
    super(msg);
  }
}
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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., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA.
 *
 * You can also choose to distribute this program under the terms of
 * the Unmodified Binary Distribution Licence (as given in the file
 * COPYING.UBDL), provided that you have satisfied its requirements.
 */

FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );

#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <ctype.h>
#include <errno.h>
#include <assert.h>
#include <byteswap.h>
#include <ipxe/if_ether.h>
#include <ipxe/iobuf.h>
#include <ipxe/netdevice.h>
#include <ipxe/device.h>
#include <ipxe/xfer.h>
#include <ipxe/open.h>
#include <ipxe/job.h>
#include <ipxe/retry.h>
#include <ipxe/tcpip.h>
#include <ipxe/ip.h>
#include <ipxe/uuid.h>
#include <ipxe/timer.h>
#include <ipxe/settings.h>
#include <ipxe/dhcp.h>
#include <ipxe/dhcpopts.h>
#include <ipxe/dhcppkt.h>
#include <ipxe/dhcparch.h>
#include <ipxe/features.h>
#include <config/dhcp.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 ( DHCP_ARCH_CLIENT_ARCHITECTURE ),
	DHCP_CLIENT_NDI, DHCP_OPTION ( DHCP_ARCH_CLIENT_NDI ),
	DHCP_VENDOR_CLASS_ID,
	DHCP_STRING ( DHCP_VENDOR_PXECLIENT ( DHCP_ARCH_CLIENT_ARCHITECTURE,
					      DHCP_ARCH_CLIENT_NDI ) ),
	DHCP_USER_CLASS_ID, DHCP_STRING ( 'i', '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_MTU, DHCP_NTP_SERVERS,
		      DHCP_VENDOR_ENCAP, DHCP_VENDOR_CLASS_ID,
		      DHCP_TFTP_SERVER_NAME, DHCP_BOOTFILE_NAME,
		      DHCP_DOMAIN_SEARCH,
		      128, 129, 130, 131, 132, 133, 134, 135, /* for PXE */
		      DHCP_EB_ENCAP, DHCP_ISCSI_INITIATOR_IQN ),
	DHCP_END
};

/** Settings copied in to all DHCP requests */
static const struct setting * dhcp_request_settings[] = {
	&user_class_setting,
	&vendor_class_setting,
};

/** DHCP server address setting */
const struct setting dhcp_server_setting __setting ( SETTING_MISC,
						     dhcp-server ) = {
	.name = "dhcp-server",
	.description = "DHCP server",
	.tag = DHCP_SERVER_IDENTIFIER,
	.type = &setting_type_ipv4,
};

/**
 * Most recent DHCP transaction ID
 *
 * This is exposed for use by the fakedhcp code when reconstructing
 * DHCP packets for PXE NBPs.
 */
uint32_t dhcp_last_xid;

/**
 * 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>";
	}
}

/****************************************************************************
 *
 * 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
	 * @v pseudo_id		DHCP server pseudo-ID
	 */
	void ( * rx ) ( struct dhcp_session *dhcp, struct dhcp_packet *dhcppkt,
			struct sockaddr_in *peer, uint8_t msgtype,
			struct in_addr server_id, struct in_addr pseudo_id );
	/**
	 * Handle timer expiry
	 *
	 * @v dhcp		DHCP session
	 */
	void ( * expired ) ( struct dhcp_session *dhcp );
	/** Transmitted message type */
	uint8_t tx_msgtype;
	/** Timeout parameters */
	uint8_t min_timeout_sec;
	uint8_t max_timeout_sec;
};

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 interface job;
	/** Data transfer interface */
	struct 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;
	/** Transaction ID (in network-endian order) */
	uint32_t xid;

	/** 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 offer */
	struct dhcp_packet *proxy_offer;
	/** ProxyDHCP offer 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;
	/** Transmission counter */
	unsigned int count;
	/** 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 );
	dhcppkt_put ( dhcp->proxy_offer );
	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 ) {

	/* Stop retry timer */
	stop_timer ( &dhcp->timer );

	/* Shut down interfaces */
	intf_shutdown ( &dhcp->xfer, rc );
	intf_shutdown ( &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 );
	set_timer_limits ( &dhcp->timer,
			   ( state->min_timeout_sec * TICKS_PER_SEC ),
			   ( state->max_timeout_sec * TICKS_PER_SEC ) );
	start_timer_nodelay ( &dhcp->timer );
}

/**
 * Check if DHCP packet contains PXE options
 *
 * @v dhcppkt		DHCP packet
 * @ret has_pxeopts	DHCP packet contains PXE options
 *
 * It is assumed that the packet is already known to contain option 60
 * set to "PXEClient".
 */
static int dhcp_has_pxeopts ( struct dhcp_packet *dhcppkt ) {

	/* Check for a next-server and boot filename */
	if ( dhcppkt->dhcphdr->siaddr.s_addr &&
	     ( dhcppkt_fetch ( dhcppkt, DHCP_BOOTFILE_NAME, NULL, 0 ) > 0 ) )
		return 1;

	/* Check for a PXE boot menu */
	if ( dhcppkt_fetch ( dhcppkt, DHCP_PXE_BOOT_MENU, NULL, 0 ) > 0 )
		return 1;

	return 0;
}

/****************************************************************************
 *
 * 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
 * @v pseudo_id		DHCP server pseudo-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 pseudo_id ) {
	struct in_addr ip;
	char vci[9]; /* "PXEClient" */
	int vci_len;
	int has_pxeclient;
	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 ) ||
	     ( pseudo_id.s_addr != peer->sin_addr.s_addr ) ) {
		DBGC ( dhcp, " (%s/", inet_ntoa ( server_id ) );
		DBGC ( dhcp, "%s)", inet_ntoa ( pseudo_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 ));
	if ( has_pxeclient ) {
		DBGC ( dhcp, "%s",
		       ( dhcp_has_pxeopts ( dhcppkt ) ? " 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 ( pseudo_id.s_addr && has_pxeclient &&
	     ( priority >= dhcp->proxy_priority ) ) {
		dhcppkt_put ( dhcp->proxy_offer );
		dhcp->proxy_server = pseudo_id;
		dhcp->proxy_offer = dhcppkt_get ( dhcppkt );
		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_offer ||
		 ( elapsed > DHCP_DISC_PROXY_TIMEOUT_SEC * TICKS_PER_SEC ) ) )
		return;

	/* Transition to DHCPREQUEST */
	dhcp_set_state ( dhcp, &dhcp_state_request );
}

/**
 * Defer DHCP discovery
 *
 * @v dhcp		DHCP session
 */
static void dhcp_defer ( struct dhcp_session *dhcp ) {

	/* Do nothing if we have reached the deferral limit */
	if ( dhcp->count > DHCP_DISC_MAX_DEFERRALS )
		return;

	/* Return to discovery state */
	DBGC ( dhcp, "DHCP %p deferring discovery\n", dhcp );
	dhcp_set_state ( dhcp, &dhcp_state_discover );

	/* Delay first DHCPDISCOVER */
	start_timer_fixed ( &dhcp->timer,
			    ( DHCP_DISC_START_TIMEOUT_SEC * TICKS_PER_SEC ) );
}

/**
 * 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 > DHCP_DISC_PROXY_TIMEOUT_SEC * TICKS_PER_SEC ) ) {
		dhcp_set_state ( dhcp, &dhcp_state_request );
		return;
	}

	/* Retransmit current packet */
	dhcp_tx ( dhcp );

	/* If link is blocked, defer DHCP discovery timeout */
	if ( netdev_link_blocked ( dhcp->netdev ) )
	     dhcp_defer ( 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,
	.min_timeout_sec	= DHCP_DISC_START_TIMEOUT_SEC,
	.max_timeout_sec	= DHCP_DISC_END_TIMEOUT_SEC,
};

/**
 * 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
 * @v pseudo_id		DHCP server pseudo-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 pseudo_id ) {
	struct in_addr ip;
	struct settings *parent;
	struct settings *settings;
	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 ) ||
	     ( pseudo_id.s_addr != peer->sin_addr.s_addr ) ) {
		DBGC ( dhcp, " (%s/", inet_ntoa ( server_id ) );
		DBGC ( dhcp, "%s)", inet_ntoa ( pseudo_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 invalid port */
	if ( peer->sin_port != htons ( BOOTPS_PORT ) )
		return;

	/* Filter out non-selected servers */
	if ( server_id.s_addr != dhcp->server.s_addr )
		return;

	/* Handle DHCPNAK */
	if ( msgtype == DHCPNAK ) {
		dhcp_defer ( dhcp );
		return;
	}

	/* Filter out unacceptable responses */
	if ( msgtype /* BOOTP */ && ( msgtype != DHCPACK ) )
		return;
	if ( ip.s_addr != dhcp->offer.s_addr )
		return;

	/* Record assigned address */
	dhcp->local.sin_addr = ip;

	/* Register settings */
	parent = netdev_settings ( dhcp->netdev );
	settings = &dhcppkt->settings;
	if ( ( rc = register_settings ( settings, parent,
					DHCP_SETTINGS_NAME ) ) != 0 ) {
		DBGC ( dhcp, "DHCP %p could not register settings: %s\n",
		       dhcp, strerror ( rc ) );
		dhcp_finished ( dhcp, rc );
		return;
	}

	/* Unregister any existing ProxyDHCP or PXEBS settings */
	if ( ( settings = find_settings ( PROXYDHCP_SETTINGS_NAME ) ) != NULL )
		unregister_settings ( settings );
	if ( ( settings = find_settings ( PXEBS_SETTINGS_NAME ) ) != NULL )
		unregister_settings ( settings );

	/* Perform ProxyDHCP if applicable */
	if ( dhcp->proxy_offer /* Have ProxyDHCP offer */ &&
	     ( ! dhcp->no_pxedhcp ) /* ProxyDHCP not disabled */ ) {
		if ( dhcp_has_pxeopts ( dhcp->proxy_offer ) ) {
			/* PXE options already present; register settings
			 * without performing a ProxyDHCPREQUEST
			 */
			settings = &dhcp->proxy_offer->settings;
			if ( ( rc = register_settings ( settings, NULL,
					   PROXYDHCP_SETTINGS_NAME ) ) != 0 ) {
				DBGC ( dhcp, "DHCP %p could not register "
				       "proxy settings: %s\n",
				       dhcp, strerror ( rc ) );
				dhcp_finished ( dhcp, rc );
				return;
			}
		} else {
			/* PXE options not present; use a ProxyDHCPREQUEST */
			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,
	.min_timeout_sec	= DHCP_REQ_START_TIMEOUT_SEC,
	.max_timeout_sec	= DHCP_REQ_END_TIMEOUT_SEC,
};

/**
 * 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\n", dhcp,
	       inet_ntoa ( dhcp->proxy_server ) );

	/* 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 = htons ( PXE_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
 * @v pseudo_id		DHCP server pseudo-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,
			    struct in_addr pseudo_id ) {
	struct settings *settings = &dhcppkt->settings;
	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 ) ||
	     ( pseudo_id.s_addr != peer->sin_addr.s_addr ) ) {
		DBGC ( dhcp, " (%s/", inet_ntoa ( server_id ) );
		DBGC ( dhcp, "%s)", inet_ntoa ( pseudo_id ) );
	}
	if ( dhcp_has_pxeopts ( dhcppkt ) )
		DBGC ( dhcp, " pxe" );
	DBGC ( dhcp, "\n" );

	/* Filter out unacceptable responses */
	if ( peer->sin_port != ntohs ( PXE_PORT ) )
		return;
	if ( ( msgtype != DHCPOFFER ) && ( msgtype != DHCPACK ) )
		return;
	if ( ( pseudo_id.s_addr != dhcp->proxy_server.s_addr ) )
		return;
	if ( ! dhcp_has_pxeopts ( dhcppkt ) )
		return;

	/* Register settings */
	if ( ( rc = register_settings ( settings, NULL,
					PROXYDHCP_SETTINGS_NAME ) ) != 0 ) {
		DBGC ( dhcp, "DHCP %p could not register proxy 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 > DHCP_REQ_PROXY_TIMEOUT_SEC * TICKS_PER_SEC ) {
		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,
	.min_timeout_sec	= DHCP_PROXY_START_TIMEOUT_SEC,
	.max_timeout_sec	= DHCP_PROXY_END_TIMEOUT_SEC,
};

/**
 * 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
 * @v pseudo_id		DHCP server pseudo-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 in_addr pseudo_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 ),