pxe_udp.c

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/** @file
 *
 * PXE UDP API
 *
 */

#include <string.h>
#include <byteswap.h>
#include <ipxe/iobuf.h>
#include <ipxe/xfer.h>
#include <ipxe/udp.h>
#include <ipxe/uaccess.h>
#include <ipxe/process.h>
#include <ipxe/netdevice.h>
#include <ipxe/malloc.h>
#include <realmode.h>
#include <pxe.h>

/*
 * Copyright (C) 2004 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 );

/** A PXE UDP pseudo-header */
struct pxe_udp_pseudo_header {
        /** Source IP address */
        IP4_t src_ip;
        /** Source port */
        UDP_PORT_t s_port;
        /** Destination IP address */
        IP4_t dest_ip;
        /** Destination port */
        UDP_PORT_t d_port;
} __attribute__ (( packed ));

/** A PXE UDP connection */
struct pxe_udp_connection {
        /** Data transfer interface to UDP stack */
        struct interface xfer;
        /** Local address */
        struct sockaddr_in local;
        /** List of received packets */
        struct list_head list;
};

/**
 * Receive PXE UDP data
 *
 * @v pxe_udp                   PXE UDP connection
 * @v iobuf                     I/O buffer
 * @v meta                      Data transfer metadata
 * @ret rc                      Return status code
 *
 * Receives a packet as part of the current pxenv_udp_read()
 * operation.
 */
static int pxe_udp_deliver ( struct pxe_udp_connection *pxe_udp,
                             struct io_buffer *iobuf,
                             struct xfer_metadata *meta ) {
        struct pxe_udp_pseudo_header *pshdr;
        struct sockaddr_in *sin_src;
        struct sockaddr_in *sin_dest;
        int rc;

        /* Extract metadata */
        assert ( meta );
        sin_src = ( struct sockaddr_in * ) meta->src;
        assert ( sin_src );
        assert ( sin_src->sin_family == AF_INET );
        sin_dest = ( struct sockaddr_in * ) meta->dest;
        assert ( sin_dest );
        assert ( sin_dest->sin_family == AF_INET );

        /* Construct pseudo-header */
        if ( ( rc = iob_ensure_headroom ( iobuf, sizeof ( *pshdr ) ) ) != 0 ) {
                DBG ( "PXE could not prepend pseudo-header\n" );
                rc = -ENOMEM;
                goto drop;
        }
        pshdr = iob_push ( iobuf, sizeof ( *pshdr ) );
        pshdr->src_ip = sin_src->sin_addr.s_addr;
        pshdr->s_port = sin_src->sin_port;
        pshdr->dest_ip = sin_dest->sin_addr.s_addr;
        pshdr->d_port = sin_dest->sin_port;

        /* Add to queue */
        list_add_tail ( &iobuf->list, &pxe_udp->list );

        return 0;

 drop:
        free_iob ( iobuf );
        return rc;
}

/** PXE UDP data transfer interface operations */
static struct interface_operation pxe_udp_xfer_operations[] = {
        INTF_OP ( xfer_deliver, struct pxe_udp_connection *, pxe_udp_deliver ),
};

/** PXE UDP data transfer interface descriptor */
static struct interface_descriptor pxe_udp_xfer_desc =
        INTF_DESC ( struct pxe_udp_connection, xfer, pxe_udp_xfer_operations );

/** The PXE UDP connection */
static struct pxe_udp_connection pxe_udp = {
        .xfer = INTF_INIT ( pxe_udp_xfer_desc ),
        .local = {
                .sin_family = AF_INET,
        },
        .list = LIST_HEAD_INIT ( pxe_udp.list ),
};

/**
 * UDP OPEN
 *
 * @v pxenv_udp_open                    Pointer to a struct s_PXENV_UDP_OPEN
 * @v s_PXENV_UDP_OPEN::src_ip          IP address of this station, or 0.0.0.0
 * @ret #PXENV_EXIT_SUCCESS             Always
 * @ret s_PXENV_UDP_OPEN::Status        PXE status code
 * @err #PXENV_STATUS_UDP_OPEN          UDP connection already open
 * @err #PXENV_STATUS_OUT_OF_RESOURCES  Could not open connection
 *
 * Prepares the PXE stack for communication using pxenv_udp_write()
 * and pxenv_udp_read().
 *
 * The IP address supplied in s_PXENV_UDP_OPEN::src_ip will be
 * recorded and used as the local station's IP address for all further
 * communication, including communication by means other than
 * pxenv_udp_write() and pxenv_udp_read().  (If
 * s_PXENV_UDP_OPEN::src_ip is 0.0.0.0, the local station's IP address
 * will remain unchanged.)
 *
 * You can only have one open UDP connection at a time.  This is not a
 * meaningful restriction, since pxenv_udp_write() and
 * pxenv_udp_read() allow you to specify arbitrary local and remote
 * ports and an arbitrary remote address for each packet.  According
 * to the PXE specifiation, you cannot have a UDP connection open at
 * the same time as a TFTP connection; this restriction does not apply
 * to Etherboot.
 *
 * On x86, you must set the s_PXE::StatusCallout field to a nonzero
 * value before calling this function in protected mode.  You cannot
 * call this function with a 32-bit stack segment.  (See the relevant
 * @ref pxe_x86_pmode16 "implementation note" for more details.)
 *
 * @note The PXE specification does not make it clear whether the IP
 * address supplied in s_PXENV_UDP_OPEN::src_ip should be used only
 * for this UDP connection, or retained for all future communication.
 * The latter seems more consistent with typical PXE stack behaviour.
 *
 * @note Etherboot currently ignores the s_PXENV_UDP_OPEN::src_ip
 * parameter.
 *
 */
static PXENV_EXIT_t pxenv_udp_open ( struct s_PXENV_UDP_OPEN *pxenv_udp_open ) {
        int rc;

        DBG ( "PXENV_UDP_OPEN" );

        /* Record source IP address */
        pxe_udp.local.sin_addr.s_addr = pxenv_udp_open->src_ip;
        DBG ( " %s\n", inet_ntoa ( pxe_udp.local.sin_addr ) );

        /* Open network device, if necessary */
        if ( pxe_netdev && ( ! netdev_is_open ( pxe_netdev ) ) &&
             ( ( rc = netdev_open ( pxe_netdev ) ) != 0 ) ) {
                DBG ( "PXENV_UDP_OPEN could not (implicitly) open %s: %s\n",
                      pxe_netdev->name, strerror ( rc ) );
                pxenv_udp_open->Status = PXENV_STATUS ( rc );
                return PXENV_EXIT_FAILURE;
        }

        /* Open promiscuous UDP connection */
        intf_restart ( &pxe_udp.xfer, 0 );
        if ( ( rc = udp_open_promisc ( &pxe_udp.xfer ) ) != 0 ) {
                DBG ( "PXENV_UDP_OPEN could not open promiscuous socket: %s\n",
                      strerror ( rc ) );
                pxenv_udp_open->Status = PXENV_STATUS ( rc );
                return PXENV_EXIT_FAILURE;
        }

        pxenv_udp_open->Status = PXENV_STATUS_SUCCESS;
        return PXENV_EXIT_SUCCESS;
}

/**
 * UDP CLOSE
 *
 * @v pxenv_udp_close                   Pointer to a struct s_PXENV_UDP_CLOSE
 * @ret #PXENV_EXIT_SUCCESS             Always
 * @ret s_PXENV_UDP_CLOSE::Status       PXE status code
 * @err None                            -
 *
 * Closes a UDP connection opened with pxenv_udp_open().
 *
 * You can only have one open UDP connection at a time.  You cannot
 * have a UDP connection open at the same time as a TFTP connection.
 * You cannot use pxenv_udp_close() to close a TFTP connection; use
 * pxenv_tftp_close() instead.
 *
 * On x86, you must set the s_PXE::StatusCallout field to a nonzero
 * value before calling this function in protected mode.  You cannot
 * call this function with a 32-bit stack segment.  (See the relevant
 * @ref pxe_x86_pmode16 "implementation note" for more details.)
 *
 */
static PXENV_EXIT_t
pxenv_udp_close ( struct s_PXENV_UDP_CLOSE *pxenv_udp_close ) {
        struct io_buffer *iobuf;
        struct io_buffer *tmp;

        DBG ( "PXENV_UDP_CLOSE\n" );

        /* Close UDP connection */
        intf_restart ( &pxe_udp.xfer, 0 );

        /* Discard any received packets */
        list_for_each_entry_safe ( iobuf, tmp, &pxe_udp.list, list ) {
                list_del ( &iobuf->list );
                free_iob ( iobuf );
        }

        pxenv_udp_close->Status = PXENV_STATUS_SUCCESS;
        return PXENV_EXIT_SUCCESS;
}

/**
 * UDP WRITE
 *
 * @v pxenv_udp_write                   Pointer to a struct s_PXENV_UDP_WRITE
 * @v s_PXENV_UDP_WRITE::ip             Destination IP address
 * @v s_PXENV_UDP_WRITE::gw             Relay agent IP address, or 0.0.0.0
 * @v s_PXENV_UDP_WRITE::src_port       Source UDP port, or 0
 * @v s_PXENV_UDP_WRITE::dst_port       Destination UDP port
 * @v s_PXENV_UDP_WRITE::buffer_size    Length of the UDP payload
 * @v s_PXENV_UDP_WRITE::buffer         Address of the UDP payload
 * @ret #PXENV_EXIT_SUCCESS             Packet was transmitted successfully
 * @ret #PXENV_EXIT_FAILURE             Packet could not be transmitted
 * @ret s_PXENV_UDP_WRITE::Status       PXE status code
 * @err #PXENV_STATUS_UDP_CLOSED        UDP connection is not open
 * @err #PXENV_STATUS_UNDI_TRANSMIT_ERROR Could not transmit packet
 *
 * Transmits a single UDP packet.  A valid IP and UDP header will be
 * prepended to the payload in s_PXENV_UDP_WRITE::buffer; the buffer
 * should not contain precomputed IP and UDP headers, nor should it
 * contain space allocated for these headers.  The first byte of the
 * buffer will be transmitted as the first byte following the UDP
 * header.
 *
 * If s_PXENV_UDP_WRITE::gw is 0.0.0.0, normal IP routing will take
 * place.  See the relevant @ref pxe_routing "implementation note" for
 * more details.
 *
 * If s_PXENV_UDP_WRITE::src_port is 0, port 2069 will be used.
 *
 * You must have opened a UDP connection with pxenv_udp_open() before
 * calling pxenv_udp_write().
 *
 * On x86, you must set the s_PXE::StatusCallout field to a nonzero
 * value before calling this function in protected mode.  You cannot
 * call this function with a 32-bit stack segment.  (See the relevant
 * @ref pxe_x86_pmode16 "implementation note" for more details.)
 *
 * @note Etherboot currently ignores the s_PXENV_UDP_WRITE::gw
 * parameter.
 *
 */
static PXENV_EXIT_t
pxenv_udp_write ( struct s_PXENV_UDP_WRITE *pxenv_udp_write ) {
        struct sockaddr_in dest;
        struct xfer_metadata meta = {
                .src = ( struct sockaddr * ) &pxe_udp.local,
                .dest = ( struct sockaddr * ) &dest,
                .netdev = pxe_netdev,
        };
        size_t len;
        struct io_buffer *iobuf;
        userptr_t buffer;
        int rc;

        DBG ( "PXENV_UDP_WRITE" );

        /* Construct destination socket address */
        memset ( &dest, 0, sizeof ( dest ) );
        dest.sin_family = AF_INET;
        dest.sin_addr.s_addr = pxenv_udp_write->ip;
        dest.sin_port = pxenv_udp_write->dst_port;

        /* Set local (source) port.  PXE spec says source port is 2069
         * if not specified.  Really, this ought to be set at UDP open
         * time but hey, we didn't design this API.
         */
        pxe_udp.local.sin_port = pxenv_udp_write->src_port;
        if ( ! pxe_udp.local.sin_port )
                pxe_udp.local.sin_port = htons ( 2069 );

        /* FIXME: we ignore the gateway specified, since we're
         * confident of being able to do our own routing.  We should
         * probably allow for multiple gateways.
         */

        /* Allocate and fill data buffer */
        len = pxenv_udp_write->buffer_size;
        iobuf = xfer_alloc_iob ( &pxe_udp.xfer, len );
        if ( ! iobuf ) {
                DBG ( " out of memory\n" );
                pxenv_udp_write->Status = PXENV_STATUS_OUT_OF_RESOURCES;
                return PXENV_EXIT_FAILURE;
        }
        buffer = real_to_user ( pxenv_udp_write->buffer.segment,
                                pxenv_udp_write->buffer.offset );
        copy_from_user ( iob_put ( iobuf, len ), buffer, 0, len );

        DBG ( " %04x:%04x+%x %d->%s:%d\n", pxenv_udp_write->buffer.segment,
              pxenv_udp_write->buffer.offset, pxenv_udp_write->buffer_size,
              ntohs ( pxenv_udp_write->src_port ),
              inet_ntoa ( dest.sin_addr ),
              ntohs ( pxenv_udp_write->dst_port ) );
        
        /* Transmit packet */
        if ( ( rc = xfer_deliver ( &pxe_udp.xfer, iobuf, &meta ) ) != 0 ) {
                DBG ( "PXENV_UDP_WRITE could not transmit: %s\n",
                      strerror ( rc ) );
                pxenv_udp_write->Status = PXENV_STATUS ( rc );
                return PXENV_EXIT_FAILURE;
        }

        pxenv_udp_write->Status = PXENV_STATUS_SUCCESS;
        return PXENV_EXIT_SUCCESS;
}

/**
 * UDP READ
 *
 * @v pxenv_udp_read                    Pointer to a struct s_PXENV_UDP_READ
 * @v s_PXENV_UDP_READ::dest_ip         Destination IP address, or 0.0.0.0
 * @v s_PXENV_UDP_READ::d_port          Destination UDP port, or 0
 * @v s_PXENV_UDP_READ::buffer_size     Size of the UDP payload buffer
 * @v s_PXENV_UDP_READ::buffer          Address of the UDP payload buffer
 * @ret #PXENV_EXIT_SUCCESS             A packet has been received
 * @ret #PXENV_EXIT_FAILURE             No packet has been received
 * @ret s_PXENV_UDP_READ::Status        PXE status code
 * @ret s_PXENV_UDP_READ::src_ip        Source IP address
 * @ret s_PXENV_UDP_READ::dest_ip       Destination IP address
 * @ret s_PXENV_UDP_READ::s_port        Source UDP port
 * @ret s_PXENV_UDP_READ::d_port        Destination UDP port
 * @ret s_PXENV_UDP_READ::buffer_size   Length of UDP payload
 * @err #PXENV_STATUS_UDP_CLOSED        UDP connection is not open
 * @err #PXENV_STATUS_FAILURE           No packet was ready to read
 *
 * Receive a single UDP packet.  This is a non-blocking call; if no
 * packet is ready to read, the call will return instantly with
 * s_PXENV_UDP_READ::Status==PXENV_STATUS_FAILURE.
 *
 * If s_PXENV_UDP_READ::dest_ip is 0.0.0.0, UDP packets addressed to
 * any IP address will be accepted and may be returned to the caller.
 *
 * If s_PXENV_UDP_READ::d_port is 0, UDP packets addressed to any UDP
 * port will be accepted and may be returned to the caller.
 *
 * You must have opened a UDP connection with pxenv_udp_open() before
 * calling pxenv_udp_read().
 *
 * On x86, you must set the s_PXE::StatusCallout field to a nonzero
 * value before calling this function in protected mode.  You cannot
 * call this function with a 32-bit stack segment.  (See the relevant
 * @ref pxe_x86_pmode16 "implementation note" for more details.)
 *
 * @note The PXE specification (version 2.1) does not state that we
 * should fill in s_PXENV_UDP_READ::dest_ip and
 * s_PXENV_UDP_READ::d_port, but Microsoft Windows' NTLDR program
 * expects us to do so, and will fail if we don't.
 *
 */
static PXENV_EXIT_t pxenv_udp_read ( struct s_PXENV_UDP_READ *pxenv_udp_read ) {
        struct in_addr dest_ip_wanted = { .s_addr = pxenv_udp_read->dest_ip };
        struct in_addr dest_ip;
        struct io_buffer *iobuf;
        struct pxe_udp_pseudo_header *pshdr;
        uint16_t d_port_wanted = pxenv_udp_read->d_port;
        uint16_t d_port;
        userptr_t buffer;
        size_t len;

        /* Try receiving a packet, if the queue is empty */
        if ( list_empty ( &pxe_udp.list ) )
                step();

        /* Remove first packet from the queue */
        iobuf = list_first_entry ( &pxe_udp.list, struct io_buffer, list );
        if ( ! iobuf ) {
                /* No packet received */
                DBG2 ( "PXENV_UDP_READ\n" );
                goto no_packet;
        }
        list_del ( &iobuf->list );

        /* Strip pseudo-header */
        assert ( iob_len ( iobuf ) >= sizeof ( *pshdr ) );
        pshdr = iobuf->data;
        iob_pull ( iobuf, sizeof ( *pshdr ) );
        dest_ip.s_addr = pshdr->dest_ip;
        d_port = pshdr->d_port;
        DBG ( "PXENV_UDP_READ" );

        /* Filter on destination address and/or port */
        if ( dest_ip_wanted.s_addr &&
             ( dest_ip_wanted.s_addr != dest_ip.s_addr ) ) {
                DBG ( " wrong IP %s", inet_ntoa ( dest_ip ) );
                DBG ( " (wanted %s)\n", inet_ntoa ( dest_ip_wanted ) );
                goto drop;
        }
        if ( d_port_wanted && ( d_port_wanted != d_port ) ) {
                DBG ( " wrong port %d", htons ( d_port ) );
                DBG ( " (wanted %d)\n", htons ( d_port_wanted ) );
                goto drop;
        }

        /* Copy packet to buffer and record length */
        buffer = real_to_user ( pxenv_udp_read->buffer.segment,
                                pxenv_udp_read->buffer.offset );
        len = iob_len ( iobuf );
        if ( len > pxenv_udp_read->buffer_size )
                len = pxenv_udp_read->buffer_size;
        copy_to_user ( buffer, 0, iobuf->data, len );
        pxenv_udp_read->buffer_size = len;

        /* Fill in source/dest information */
        pxenv_udp_read->src_ip = pshdr->src_ip;
        pxenv_udp_read->s_port = pshdr->s_port;
        pxenv_udp_read->dest_ip = pshdr->dest_ip;
        pxenv_udp_read->d_port = pshdr->d_port;

        DBG ( " %04x:%04x+%x %s:", pxenv_udp_read->buffer.segment,
              pxenv_udp_read->buffer.offset, pxenv_udp_read->buffer_size,
              inet_ntoa ( *( ( struct in_addr * ) &pxenv_udp_read->src_ip ) ));
        DBG ( "%d<-%s:%d\n",  ntohs ( pxenv_udp_read->s_port ),
              inet_ntoa ( *( ( struct in_addr * ) &pxenv_udp_read->dest_ip ) ),
              ntohs ( pxenv_udp_read->d_port ) );

        /* Free I/O buffer */
        free_iob ( iobuf );

        pxenv_udp_read->Status = PXENV_STATUS_SUCCESS;
        return PXENV_EXIT_SUCCESS;

 drop:
        free_iob ( iobuf );
 no_packet:
        pxenv_udp_read->Status = PXENV_STATUS_FAILURE;
        return PXENV_EXIT_FAILURE;
}

/** PXE UDP API */
struct pxe_api_call pxe_udp_api[] __pxe_api_call = {
        PXE_API_CALL ( PXENV_UDP_OPEN, pxenv_udp_open,
                       struct s_PXENV_UDP_OPEN ),
        PXE_API_CALL ( PXENV_UDP_CLOSE, pxenv_udp_close,
                       struct s_PXENV_UDP_CLOSE ),
        PXE_API_CALL ( PXENV_UDP_WRITE, pxenv_udp_write,
                       struct s_PXENV_UDP_WRITE ),
        PXE_API_CALL ( PXENV_UDP_READ, pxenv_udp_read,
                       struct s_PXENV_UDP_READ ),
};

/**
 * Discard some cached PXE UDP data
 *
 * @ret discarded       Number of cached items discarded
 */
static unsigned int pxe_udp_discard ( void ) {
        struct io_buffer *iobuf;
        unsigned int discarded = 0;

        /* Try to discard the oldest received UDP packet */
        iobuf = list_first_entry ( &pxe_udp.list, struct io_buffer, list );
        if ( iobuf ) {
                list_del ( &iobuf->list );
                free_iob ( iobuf );
                discarded++;
        }

        return discarded;
}

/** PXE UDP cache discarder */
struct cache_discarder pxe_udp_discarder __cache_discarder ( CACHE_NORMAL ) = {
        .discard = pxe_udp_discard,
};