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., 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 );
FILE_SECBOOT ( PERMITTED );

#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, DHCP_STATIC_ROUTES,
                      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 ),
               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 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, pseudo_id ) )
                return;

        /* Register settings */
        if ( ( rc = register_settings ( &dhcppkt->settings, NULL,
                                        PXEBS_SETTINGS_NAME ) ) != 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_SEC * TICKS_PER_SEC ) {
                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,
        .min_timeout_sec        = PXEBS_START_TIMEOUT_SEC,
        .max_timeout_sec        = PXEBS_END_TIMEOUT_SEC,
};

/****************************************************************************
 *
 * Packet construction
 *
 */

/**
 * Create a DHCP packet
 *
 * @v dhcppkt           DHCP packet structure to fill in
 * @v netdev            Network device
 * @v msgtype           DHCP message type
 * @v xid               Transaction ID (in network-endian order)
 * @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,
                         uint32_t xid, const void *options, size_t options_len,
                         void *data, size_t max_len ) {
        struct dhcphdr *dhcphdr = data;
        int rc;

        /* Sanity check */
        if ( max_len < ( sizeof ( *dhcphdr ) + options_len ) )
                return -ENOSPC;

        /* Initialise DHCP packet content */
        memset ( dhcphdr, 0, max_len );
        dhcphdr->xid = xid;
        dhcphdr->magic = htonl ( DHCP_MAGIC_COOKIE );
        dhcphdr->htype = ntohs ( netdev->ll_protocol->ll_proto );
        dhcphdr->op = dhcp_op[msgtype];
        dhcphdr->hlen = netdev->ll_protocol->ll_addr_len;
        memcpy ( dhcphdr->chaddr, netdev->ll_addr,
                 netdev->ll_protocol->ll_addr_len );
        memcpy ( dhcphdr->options, options, options_len );

        /* If the local link-layer address functions only as a name
         * (i.e. cannot be used as a destination address), then
         * request broadcast responses.
         */
        if ( netdev->ll_protocol->flags & LL_NAME_ONLY )
                dhcphdr->flags |= htons ( BOOTP_FL_BROADCAST );

        /* If the network device already has an IPv4 address then
         * unicast responses from the DHCP server may be rejected, so
         * request broadcast responses.
         */
        if ( ipv4_has_any_addr ( netdev ) )
                dhcphdr->flags |= htons ( BOOTP_FL_BROADCAST );

        /* 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 xid               Transaction ID (in network-endian order)
 * @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,
                          uint32_t xid, 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;
        const struct setting *setting;
        uint8_t *dhcp_features;
        size_t dhcp_features_len;
        size_t ll_addr_len;
        void *raw;
        ssize_t len;
        unsigned int i;
        int rc;

        /* Create DHCP packet */
        if ( ( rc = dhcp_create_packet ( dhcppkt, netdev, msgtype, xid,
                                         dhcp_request_options_data,
                                         sizeof ( dhcp_request_options_data ),
                                         data, max_len ) ) != 0 ) {
                DBG ( "DHCP could not create DHCP packet: %s\n",
                      strerror ( rc ) );
                goto err_create_packet;
        }

        /* 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 ) );
                goto err_store_features;
        }

        /* Add options to identify the network device */
        fetch_raw_setting ( netdev_settings ( netdev ), &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 ) );
                goto err_store_busid;
        }

        /* 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 ) );
                goto err_store_client_id;
        }

        /* Add client UUID, if we have one.  Required for PXE.  The
         * PXE spec does not specify a byte ordering for UUIDs, but
         * RFC4578 suggests that it follows the EFI spec, in which the
         * first three fields are little-endian.
         */
        client_uuid.type = DHCP_CLIENT_UUID_TYPE;
        if ( ( len = fetch_uuid_setting ( NULL, &uuid_setting,
                                          &client_uuid.uuid ) ) >= 0 ) {
                uuid_mangle ( &client_uuid.uuid );
                if ( ( rc = dhcppkt_store ( dhcppkt, DHCP_CLIENT_UUID,
                                            &client_uuid,
                                            sizeof ( client_uuid ) ) ) != 0 ) {
                        DBG ( "DHCP could not set client UUID: %s\n",
                              strerror ( rc ) );
                        goto err_store_client_uuid;
                }
        }

        /* Add request settings, if applicable */
        for ( i = 0 ; i < ( sizeof ( dhcp_request_settings ) /
                            sizeof ( dhcp_request_settings[0] ) ) ; i++ ) {
                setting = dhcp_request_settings[i];
                if ( ( len = fetch_raw_setting_copy ( NULL, setting,
                                                      &raw ) ) >= 0 ) {
                        rc = dhcppkt_store ( dhcppkt, setting->tag, raw, len );
                        free ( raw );
                        if ( rc != 0 ) {
                                DBG ( "DHCP could not set %s: %s\n",
                                      setting->name, strerror ( rc ) );
                                goto err_store_raw;
                        }
                }
        }

 err_store_raw:
 err_store_client_uuid:
 err_store_client_id:
 err_store_busid:
 err_store_features:
 err_create_packet:
        return rc;
}

/****************************************************************************
 *
 * Data transfer interface
 *
 */

/**
 * Transmit DHCP request
 *
 * @v dhcp              DHCP session
 * @ret rc              Return status code
 */
static int dhcp_tx ( struct dhcp_session *dhcp ) {
        static struct sockaddr_in peer = {
                .sin_family = AF_INET,
        };
        struct xfer_metadata meta = {
                .netdev = dhcp->netdev,
                .src = ( struct sockaddr * ) &dhcp->local,
                .dest = ( struct sockaddr * ) &peer,
        };
        struct io_buffer *iobuf;
        uint8_t msgtype = dhcp->state->tx_msgtype;
        struct dhcp_packet dhcppkt;
        int rc;

        /* Start retry timer.  Do this first so that failures to
         * transmit will be retried.
         */
        start_timer ( &dhcp->timer );

        /* Allocate buffer for packet */
        iobuf = xfer_alloc_iob ( &dhcp->xfer, DHCP_MIN_LEN );
        if ( ! iobuf )
                return -ENOMEM;

        /* Create basic DHCP packet in temporary buffer */
        if ( ( rc = dhcp_create_request ( &dhcppkt, dhcp->netdev, msgtype,
                                          dhcp->xid, dhcp->local.sin_addr,
                                          iobuf->data,
                                          iob_tailroom ( iobuf ) ) ) != 0 ) {
                DBGC ( dhcp, "DHCP %p could not construct DHCP request: %s\n",
                       dhcp, strerror ( rc ) );
                goto done;
        }

        /* (Ab)use the "secs" field to convey metadata about the DHCP
         * session state into packet traces.  Useful for extracting
         * debug information from non-debug builds.
         */
        dhcppkt.dhcphdr->secs = htons ( ( dhcp->count << 2 ) |
                                        ( dhcp->offer.s_addr ? 0x02 : 0 ) |
                                        ( dhcp->proxy_offer ? 0x01 : 0 ) );

        /* Fill in packet based on current state */
        if ( ( rc = dhcp->state->tx ( dhcp, &dhcppkt, &peer ) ) != 0 ) {
                DBGC ( dhcp, "DHCP %p could not fill DHCP request: %s\n",
                       dhcp, strerror ( rc ) );
                goto done;
        }

        /* Transmit the packet */
        iob_put ( iobuf, dhcppkt_len ( &dhcppkt ) );
        if ( ( rc = xfer_deliver ( &dhcp->xfer, iob_disown ( iobuf ),
                                   &meta ) ) != 0 ) {
                DBGC ( dhcp, "DHCP %p could not transmit UDP packet: %s\n",
                       dhcp, strerror ( rc ) );
                goto done;
        }

 done:
        free_iob ( iobuf );
        return rc;
}

/**
 * Receive new data
 *
 * @v dhcp              DHCP session
 * @v iobuf             I/O buffer
 * @v meta              Transfer metadata
 * @ret rc              Return status code
 */
static int dhcp_deliver ( struct dhcp_session *dhcp,
                          struct io_buffer *iobuf,
                          struct xfer_metadata *meta ) {
        struct net_device *netdev = dhcp->netdev;
        struct ll_protocol *ll_protocol = netdev->ll_protocol;
        struct sockaddr_in *peer;
        size_t data_len;
        struct dhcp_packet *dhcppkt;
        struct dhcphdr *dhcphdr;
        uint8_t msgtype = 0;
        struct in_addr server_id = { 0 };
        struct in_addr pseudo_id;
        int rc = 0;

        /* Sanity checks */
        if ( ! meta->src ) {
                DBGC ( dhcp, "DHCP %p received packet without source port\n",
                       dhcp );
                rc = -EINVAL;
                goto err_no_src;
        }
        peer = ( struct sockaddr_in * ) meta->src;

        /* Create a DHCP packet containing the I/O buffer contents.
         * Whilst we could just use the original buffer in situ, that
         * would waste the unused space in the packet buffer, and also
         * waste a relatively scarce fully-aligned I/O buffer.
         */
        data_len = iob_len ( iobuf );
        dhcppkt = zalloc ( sizeof ( *dhcppkt ) + data_len );
        if ( ! dhcppkt ) {
                rc = -ENOMEM;
                goto err_alloc_dhcppkt;
        }
        dhcphdr = ( ( ( void * ) dhcppkt ) + sizeof ( *dhcppkt ) );
        memcpy ( dhcphdr, iobuf->data, data_len );
        dhcppkt_init ( dhcppkt, dhcphdr, data_len );

        /* Identify message type */
        dhcppkt_fetch ( dhcppkt, DHCP_MESSAGE_TYPE, &msgtype,
                        sizeof ( msgtype ) );

        /* Identify server ID */
        dhcppkt_fetch ( dhcppkt, DHCP_SERVER_IDENTIFIER,
                        &server_id, sizeof ( server_id ) );

        /* Identify server pseudo-ID */
        pseudo_id = server_id;
        if ( ! pseudo_id.s_addr )
                pseudo_id = dhcppkt->dhcphdr->siaddr;
        if ( ! pseudo_id.s_addr )
                pseudo_id = peer->sin_addr;

        /* Check for matching transaction ID */
        if ( dhcphdr->xid != dhcp->xid ) {
                DBGC ( dhcp, "DHCP %p %s from %s:%d has bad transaction "
                       "ID\n", dhcp, dhcp_msgtype_name ( msgtype ),
                       inet_ntoa ( peer->sin_addr ),
                       ntohs ( peer->sin_port ) );
                rc = -EINVAL;
                goto err_xid;
        };

        /* Check for matching client hardware address */
        if ( memcmp ( dhcphdr->chaddr, netdev->ll_addr,
                      ll_protocol->ll_addr_len ) != 0 ) {
                DBGC ( dhcp, "DHCP %p %s from %s:%d has bad chaddr %s\n",
                       dhcp, dhcp_msgtype_name ( msgtype ),
                       inet_ntoa ( peer->sin_addr ), ntohs ( peer->sin_port ),
                       ll_protocol->ntoa ( dhcphdr->chaddr ) );
                rc = -EINVAL;
                goto err_chaddr;
        }

        /* Handle packet based on current state */
        dhcp->state->rx ( dhcp, dhcppkt, peer, msgtype, server_id, pseudo_id );

 err_chaddr:
 err_xid:
        dhcppkt_put ( dhcppkt );
 err_alloc_dhcppkt:
 err_no_src:
        free_iob ( iobuf );
        return rc;
}

/** DHCP data transfer interface operations */
static struct interface_operation dhcp_xfer_operations[] = {
        INTF_OP ( xfer_deliver, struct dhcp_session *, dhcp_deliver ),
};

/** DHCP data transfer interface descriptor */
static struct interface_descriptor dhcp_xfer_desc =
        INTF_DESC ( struct dhcp_session, xfer, dhcp_xfer_operations );

/**
 * Handle DHCP retry timer expiry
 *
 * @v timer             DHCP retry timer
 * @v fail              Failure indicator
 */
static void dhcp_timer_expired ( struct retry_timer *timer, int fail ) {
        struct dhcp_session *dhcp =
                container_of ( timer, struct dhcp_session, timer );

        /* If we have failed, terminate DHCP */
        if ( fail ) {
                dhcp_finished ( dhcp, -ETIMEDOUT );
                return;
        }

        /* Increment transmission counter */
        dhcp->count++;

        /* Handle timer expiry based on current state */
        dhcp->state->expired ( dhcp );
}

/****************************************************************************
 *
 * Job control interface
 *
 */

/** DHCP job control interface operations */
static struct interface_operation dhcp_job_op[] = {
        INTF_OP ( intf_close, struct dhcp_session *, dhcp_finished ),
};

/** DHCP job control interface descriptor */
static struct interface_descriptor dhcp_job_desc =
        INTF_DESC ( struct dhcp_session, job, dhcp_job_op );

/****************************************************************************
 *
 * Instantiators
 *
 */

/**
 * DHCP peer address for socket opening
 *
 * This is a dummy address; the only useful portion is the socket
 * family (so that we get a UDP connection).  The DHCP client will set
 * the IP address and source port explicitly on each transmission.
 */
static struct sockaddr dhcp_peer = {
        .sa_family = AF_INET,
};

/**
 * Start DHCP state machine on a network device
 *
 * @v job               Job control interface
 * @v netdev            Network device
 * @ret rc              Return status code
 *
 * Starts DHCP on the specified network device.  If successful, the
 * DHCPACK (and ProxyDHCPACK, if applicable) will be registered as
 * option sources.
 */
int start_dhcp ( struct interface *job, struct net_device *netdev ) {
        struct dhcp_session *dhcp;
        int rc;

        /* Allocate and initialise structure */
        dhcp = zalloc ( sizeof ( *dhcp ) );
        if ( ! dhcp )
                return -ENOMEM;
        ref_init ( &dhcp->refcnt, dhcp_free );
        intf_init ( &dhcp->job, &dhcp_job_desc, &dhcp->refcnt );
        intf_init ( &dhcp->xfer, &dhcp_xfer_desc, &dhcp->refcnt );
        timer_init ( &dhcp->timer, dhcp_timer_expired, &dhcp->refcnt );
        dhcp->netdev = netdev_get ( netdev );
        dhcp->local.sin_family = AF_INET;
        dhcp->local.sin_port = htons ( BOOTPC_PORT );
        dhcp->xid = random();

        /* Store DHCP transaction ID for fakedhcp code */
        dhcp_last_xid = dhcp->xid;

        /* Instantiate child objects and attach to our interfaces */
        if ( ( rc = xfer_open_socket ( &dhcp->xfer, SOCK_DGRAM, &dhcp_peer,
                                  ( struct sockaddr * ) &dhcp->local ) ) != 0 )
                goto err;

        /* Enter DHCPDISCOVER state */
        dhcp_set_state ( dhcp, &dhcp_state_discover );

        /* Attach parent interface, mortalise self, and return */
        intf_plug_plug ( &dhcp->job, job );
        ref_put ( &dhcp->refcnt );
        return 0;

 err:
        dhcp_finished ( dhcp, rc );
        ref_put ( &dhcp->refcnt );
        return rc;
}

/**
 * Retrieve list of PXE boot servers for a given server type
 *
 * @v dhcp              DHCP session
 * @v raw               DHCP PXE boot server list
 * @v raw_len           Length of DHCP PXE boot server list
 * @v ip                IP address list to fill in
 *
 * The caller must ensure that the IP address list has sufficient
 * space.
 */
static void pxebs_list ( struct dhcp_session *dhcp, void *raw,
                         size_t raw_len, struct in_addr *ip ) {
        struct dhcp_pxe_boot_server *server = raw;
        size_t server_len;
        unsigned int i;

        while ( raw_len ) {
                if ( raw_len < sizeof ( *server ) ) {
                        DBGC ( dhcp, "DHCP %p malformed PXE server list\n",
                               dhcp );
                        break;
                }
                server_len = offsetof ( typeof ( *server ),
                                        ip[ server->num_ip ] );
                if ( raw_len < server_len ) {
                        DBGC ( dhcp, "DHCP %p malformed PXE server list\n",
                               dhcp );
                        break;
                }
                if ( server->type == dhcp->pxe_type ) {
                        for ( i = 0 ; i < server->num_ip ; i++ )
                                *(ip++) = server->ip[i];
                }
                server = ( ( ( void * ) server ) + server_len );
                raw_len -= server_len;
        }
}

/**
 * Start PXE Boot Server Discovery on a network device
 *
 * @v job               Job control interface
 * @v netdev            Network device
 * @v pxe_type          PXE server type
 * @ret rc              Return status code
 *
 * Starts PXE Boot Server Discovery on the specified network device.
 * If successful, the Boot Server ACK will be registered as an option
 * source.
 */
int start_pxebs ( struct interface *job, struct net_device *netdev,
                  unsigned int pxe_type ) {
        struct setting pxe_discovery_control_setting =
                { .tag = DHCP_PXE_DISCOVERY_CONTROL };
        struct setting pxe_boot_servers_setting =
                { .tag = DHCP_PXE_BOOT_SERVERS };
        struct setting pxe_boot_server_mcast_setting =
                { .tag = DHCP_PXE_BOOT_SERVER_MCAST };
        ssize_t pxebs_list_len;
        struct dhcp_session *dhcp;
        struct in_addr *ip;
        unsigned int pxe_discovery_control;
        int rc;

        /* Get upper bound for PXE boot server IP address list */
        pxebs_list_len = fetch_raw_setting ( NULL, &pxe_boot_servers_setting,
                                             NULL, 0 );
        if ( pxebs_list_len < 0 )
                pxebs_list_len = 0;

        /* Allocate and initialise structure */
        dhcp = zalloc ( sizeof ( *dhcp ) + sizeof ( *ip ) /* mcast */ +
                        sizeof ( *ip ) /* bcast */ + pxebs_list_len +
                        sizeof ( *ip ) /* terminator */ );
        if ( ! dhcp )
                return -ENOMEM;
        ref_init ( &dhcp->refcnt, dhcp_free );
        intf_init ( &dhcp->job, &dhcp_job_desc, &dhcp->refcnt );
        intf_init ( &dhcp->xfer, &dhcp_xfer_desc, &dhcp->refcnt );
        timer_init ( &dhcp->timer, dhcp_timer_expired, &dhcp->refcnt );
        dhcp->netdev = netdev_get ( netdev );
        dhcp->local.sin_family = AF_INET;
        fetch_ipv4_setting ( netdev_settings ( netdev ), &ip_setting,
                             &dhcp->local.sin_addr );
        dhcp->local.sin_port = htons ( BOOTPC_PORT );
        dhcp->pxe_type = cpu_to_le16 ( pxe_type );

        /* Construct PXE boot server IP address lists */
        pxe_discovery_control =
                fetch_uintz_setting ( NULL, &pxe_discovery_control_setting );
        ip = ( ( ( void * ) dhcp ) + sizeof ( *dhcp ) );
        dhcp->pxe_attempt = ip;
        if ( ! ( pxe_discovery_control & PXEBS_NO_MULTICAST ) ) {
                fetch_ipv4_setting ( NULL, &pxe_boot_server_mcast_setting, ip);
                if ( ip->s_addr )
                        ip++;
        }
        if ( ! ( pxe_discovery_control & PXEBS_NO_BROADCAST ) )
                (ip++)->s_addr = INADDR_BROADCAST;
        if ( pxe_discovery_control & PXEBS_NO_UNKNOWN_SERVERS )
                dhcp->pxe_accept = ip;
        if ( pxebs_list_len ) {
                uint8_t buf[pxebs_list_len];

                fetch_raw_setting ( NULL, &pxe_boot_servers_setting,
                                    buf, sizeof ( buf ) );
                pxebs_list ( dhcp, buf, sizeof ( buf ), ip );
        }
        if ( ! dhcp->pxe_attempt->s_addr ) {
                DBGC ( dhcp, "DHCP %p has no PXE boot servers for type %04x\n",
                       dhcp, pxe_type );
                rc = -EINVAL;
                goto err;
        }

        /* Dump out PXE server lists */
        DBGC ( dhcp, "DHCP %p attempting", dhcp );
        for ( ip = dhcp->pxe_attempt ; ip->s_addr ; ip++ )
                DBGC ( dhcp, " %s", inet_ntoa ( *ip ) );
        DBGC ( dhcp, "\n" );
        if ( dhcp->pxe_accept ) {
                DBGC ( dhcp, "DHCP %p accepting", dhcp );
                for ( ip = dhcp->pxe_accept ; ip->s_addr ; ip++ )
                        DBGC ( dhcp, " %s", inet_ntoa ( *ip ) );
                DBGC ( dhcp, "\n" );
        }

        /* Instantiate child objects and attach to our interfaces */
        if ( ( rc = xfer_open_socket ( &dhcp->xfer, SOCK_DGRAM, &dhcp_peer,
                                  ( struct sockaddr * ) &dhcp->local ) ) != 0 )
                goto err;

        /* Enter PXEBS state */
        dhcp_set_state ( dhcp, &dhcp_state_pxebs );

        /* Attach parent interface, mortalise self, and return */
        intf_plug_plug ( &dhcp->job, job );
        ref_put ( &dhcp->refcnt );
        return 0;

 err:
        dhcp_finished ( dhcp, rc );
        ref_put ( &dhcp->refcnt );
        return rc;
}

/** DHCP network device configurator */
struct net_device_configurator dhcp_configurator __net_device_configurator = {
        .name = "dhcp",
        .start = start_dhcp,
};