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/*

 * Copyright (c) 2008 Lukas Mejdrech

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 *

 * - Redistributions of source code must retain the above copyright

 *   notice, this list of conditions and the following disclaimer.

 * - Redistributions in binary form must reproduce the above copyright

 *   notice, this list of conditions and the following disclaimer in the

 *   documentation and/or other materials provided with the distribution.

 * - The name of the author may not be used to endorse or promote products

 *   derived from this software without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR

 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES

 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.

 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,

 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT

 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,

 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY

 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF

 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 */

/** @addtogroup udp

 *  @{

 */

/** @file

 *  UDP module implementation.

 *  @see udp.h

 */

#include <async.h>

#include <fibril_sync.h>

#include <malloc.h>

#include <ipc/ipc.h>

#include <ipc/services.h>

#include "../../err.h"

#include "../../messages.h"

#include "../../modules.h"

#include "../../structures/dynamic_fifo.h"

#include "../../structures/packet/packet_client.h"

#include "../../include/crc.h"

#include "../../include/in.h"

#include "../../include/in6.h"

#include "../../include/inet.h"

#include "../../include/ip_client.h"

#include "../../include/ip_interface.h"

#include "../../include/ip_protocols.h"

#include "../../include/icmp_client.h"

#include "../../include/icmp_interface.h"

#include "../../include/net_interface.h"

#include "../../include/socket_codes.h"

#include "../../include/socket_errno.h"

#include "../../socket/socket_core.h"

#include "../../socket/socket_messages.h"

#include "../tl_common.h"

#include "../tl_messages.h"

#include "udp.h"

#include "udp_header.h"

#include "udp_module.h"

/** Default UDP checksum computing.

 */

#define NET_DEFAULT_UDP_CHECKSUM_COMPUTING  true

/** Maximum UDP fragment size.

 */

#define MAX_UDP_FRAGMENT_SIZE   65535

/** Free ports pool start.

 */

#define UDP_FREE_PORTS_START    1025

/** Free ports pool end.

 */

#define UDP_FREE_PORTS_END      65535

/** Processes the received UDP packet queue.

 *  Is used as an entry point from the underlying IP module.

 *  Notifies the destination socket application.

 *  Releases the packet on error or send an ICMP error notification..

 *  @param device_id The device identifier. Ignored parameter.

 *  @param packet The received packet queue. Input/output parameter.

 *  @param receiver The target service. Ignored parameter.

 *  @param error The packet error reporting service. Prefixes the received packet. Input parameter.

 *  @returns EOK on success.

 *  @returns EINVAL if the packet is not valid.

 *  @returns EINVAL if the stored packet address is not the an_addr_t.

 *  @returns EINVAL if the packet does not contain any data.

 *  @returns NO_DATA if the packet content is shorter than the user datagram header.

 *  @returns ENOMEM if there is not enough memory left.

 *  @returns EADDRNOTAVAIL if the destination socket does not exist.

 *  @returns Other error codes as defined for the ip_client_process_packet() function.

 */

int udp_received_msg( device_id_t device_id, packet_t packet, services_t receiver, services_t error );

/** Releases the packet and returns the result.

 *  @param packet The packet queue to be released. Input parameter.

 *  @param result The result to be returned. Input parameter.

 *  @return The result parameter.

 */

int udp_release_and_return( packet_t packet, int result );

/** @name Socket messages processing functions

 */

/*@{*/

/** Processes the socket client messages.

 *  Runs until the client module disconnects.

 *  @param callid The message identifier. Input parameter.

 *  @param call The message parameters. Input parameter.

 *  @returns EOK on success.

 *  @see socket.h

 */

int udp_process_client_messages( ipc_callid_t callid, ipc_call_t call );

/** Sends data from the socket to the remote address.

 *  Binds the socket to a free port if not already connected/bound.

 *  Handles the NET_SOCKET_SENDTO message.

 *  Supports AF_INET and AF_INET6 address families.

 *  @param local_sockets The application local sockets. Input/output parameter.

 *  @param socket_id Socket identifier. Input parameter.

 *  @param addr The destination address. Input parameter.

 *  @param addrlen The address length. Input parameter.

 *  @param fragments The number of data fragments. Input parameter.

 *  @param data_fragment_size The data fragment size in bytes. Input parameter.

 *  @param flags Various send flags. Input parameter.

 *  @returns EOK on success.

 *  @returns EAFNOTSUPPORT if the address family is not supported.

 *  @returns ENOTSOCK if the socket is not found.

 *  @returns EINVAL if the address is invalid.

 *  @returns ENOTCONN if the sending socket is not and cannot be bound.

 *  @returns ENOMEM if there is not enough memory left.

 *  @returns Other error codes as defined for the socket_read_packet_data() function.

 *  @returns Other error codes as defined for the ip_client_prepare_packet() function.

 *  @returns Other error codes as defined for the ip_send_msg() function.

 */

int udp_sendto_message( socket_cores_ref local_sockets, int socket_id, const struct sockaddr * addr, socklen_t addrlen, int fragments, size_t data_fragment_size, int flags );

/** Receives data to the socket.

 *  Handles the NET_SOCKET_RECVFROM message.

 *  Replies the source address as well.

 *  @param local_sockets The application local sockets. Input parameter.

 *  @param socket_id Socket identifier. Input parameter.

 *  @param flags Various receive flags. Input parameter.

 *  @param addrlen The source address length. Output parameter.

 *  @returns The number of bytes received.

 *  @returns ENOTSOCK if the socket is not found.

 *  @returns NO_DATA if there are no received packets or data.

 *  @returns ENOMEM if there is not enough memory left.

 *  @returns EINVAL if the received address is not an IP address.

 *  @returns Other error codes as defined for the packet_translate() function.

 *  @returns Other error codes as defined for the data_reply() function.

 */

int udp_recvfrom_message( socket_cores_ref local_sockets, int socket_id, int flags, size_t * addrlen );

/*@}*/

/** UDP global data.

 */

udp_globals_t   udp_globals;

int udp_initialize( async_client_conn_t client_connection ){

    ERROR_DECLARE;

    measured_string_t   names[] = {{ "UDP_CHECKSUM_COMPUTING", 22 }};

    measured_string_ref configuration;

    size_t              count = sizeof( names ) / sizeof( measured_string_t );

    char *              data;

    fibril_rwlock_initialize( & udp_globals.lock );

    fibril_rwlock_write_lock( & udp_globals.lock );

    udp_globals.icmp_phone = icmp_connect_module( SERVICE_ICMP );

    if( udp_globals.icmp_phone < 0 ){

        return udp_globals.icmp_phone;

    }

    udp_globals.ip_phone = ip_bind_service( SERVICE_IP, IPPROTO_UDP, SERVICE_UDP, client_connection, udp_received_msg );

    if( udp_globals.ip_phone < 0 ){

        return udp_globals.ip_phone;

    }

    ERROR_PROPAGATE( ip_packet_size_req( udp_globals.ip_phone, -1, & udp_globals.packet_dimension.addr_len, & udp_globals.packet_dimension.prefix, & udp_globals.packet_dimension.content, & udp_globals.packet_dimension.suffix ));

    ERROR_PROPAGATE( socket_ports_initialize( & udp_globals.sockets ));

    udp_globals.packet_dimension.prefix += sizeof( udp_header_t );

    udp_globals.packet_dimension.content -= sizeof( udp_header_t );

    udp_globals.last_used_port = UDP_FREE_PORTS_START - 1;

    // get configuration

    udp_globals.checksum_computing = NET_DEFAULT_UDP_CHECKSUM_COMPUTING;

    configuration = & names[ 0 ];

    ERROR_PROPAGATE( net_get_conf_req( udp_globals.net_phone, & configuration, count, & data ));

    if( configuration ){

        if( configuration[ 0 ].value ){

            udp_globals.checksum_computing = ( configuration[ 0 ].value[ 0 ] == 'y' );

        }

        net_free_settings( configuration, data );

    }

    fibril_rwlock_write_unlock( & udp_globals.lock );

    return EOK;

}

int udp_received_msg( device_id_t device_id, packet_t packet, services_t receiver, services_t error ){

    ERROR_DECLARE;

    size_t          length;

    size_t          offset;

    int             result;

    uint8_t *       data;

    udp_header_ref  header;

    socket_core_ref *   socket;

    packet_t        next_packet;

    size_t          total_length;

    uint32_t        checksum;

    int             fragments;

    packet_t        tmp_packet;

    icmp_type_t     type;

    icmp_code_t     code;

    ip_pseudo_header_ref    ip_header;

    struct sockaddr *       src;

    struct sockaddr *       dest;

    if( error ){

        switch( error ){

            case SERVICE_ICMP:

                // process error

                // TODO remove debug dump

                // length = icmp_client_header_length( packet );

                result = icmp_client_process_packet( packet, & type, & code, NULL, NULL );

                if( result < 0 ){

                    return udp_release_and_return( packet, result );

                }

                printf( "ICMP error %d (%d) in packet %d\n", type, code, packet_get_id( packet ) );

                length = ( size_t ) result;

                if( ERROR_OCCURRED( packet_trim( packet, length, 0 ))){

                    return udp_release_and_return( packet, ERROR_CODE );

                }

                break;

            default:

                return udp_release_and_return( packet, ENOTSUP );

        }

    }

    // TODO process received ipopts?

    result = ip_client_process_packet( packet, NULL, NULL, NULL, NULL, NULL );

    if( result < 0 ){

        return udp_release_and_return( packet, result );

    }

    offset = ( size_t ) result;

    length = packet_get_data_length( packet );

    if( length <= 0 ){

        return udp_release_and_return( packet, EINVAL );

    }

    if( length < sizeof( udp_header_t ) + offset ){

        return udp_release_and_return( packet, NO_DATA );

    }

    data = packet_get_data( packet );

    if( ! data ){

        return udp_release_and_return( packet, NO_DATA );

    }

    // get udp header

    header = ( udp_header_ref )( data + offset );

    // find the destination socket

    socket = socket_ports_find( & udp_globals.sockets, ntohs( header->destination_port ));

    if( ! socket ){

        tl_send_icmp_port_unreachable( udp_globals.net_phone, udp_globals.icmp_phone, packet, error );

        return EADDRNOTAVAIL;

    }

    // trim after successful processing to be able to send an ICMP error message!

    ERROR_PROPAGATE( packet_trim( packet, offset, 0 ));

    // count the received packet fragments

    next_packet = packet;

    fragments = 0;

    total_length = ntohs( header->total_length );

    // compute header checksum if set

    if( header->checksum && ( ! error )){

        result = packet_get_addr( packet, ( uint8_t ** ) & src, ( uint8_t ** ) & dest );

        if( result <= 0 ){

            return udp_release_and_return( packet, result );

        }

        if( ERROR_OCCURRED( ip_client_get_pseudo_header( IPPROTO_UDP, src, result, dest, result, total_length, & ip_header, & length ))){

            return udp_release_and_return( packet, ERROR_CODE );

        }else{

            checksum = compute_checksum( 0, ip_header, length );

            // the udp header checksum will be added with the first fragment later

            free( ip_header );

        }

    }else{

        header->checksum = 0;

        checksum = 0;

    }

    do{

        ++ fragments;

        length = packet_get_data_length( next_packet );

        if( length <= 0 ){

            return udp_release_and_return( packet, NO_DATA );

        }

        if( total_length < length ){

            if( ERROR_OCCURRED( packet_trim( next_packet, 0, length - total_length ))){

                return udp_release_and_return( packet, ERROR_CODE );

            }

            // add partial checksum if set

            if( header->checksum ){

                checksum = compute_checksum( checksum, packet_get_data( packet ), packet_get_data_length( packet ));

            }

            // relese the rest of the packet fragments

            tmp_packet = pq_next( next_packet );

            while( tmp_packet ){

                next_packet = pq_detach( tmp_packet );

                pq_release( udp_globals.net_phone, packet_get_id( tmp_packet ));

                tmp_packet = next_packet;

            }

            // exit the loop

            break;

        }

        total_length -= length;

        // add partial checksum if set

        if( header->checksum ){

            checksum = compute_checksum( checksum, packet_get_data( packet ), packet_get_data_length( packet ));

        }

    }while(( next_packet = pq_next( next_packet )) && ( total_length > 0 ));

    // check checksum

    if( header->checksum ){

        if( flip_checksum( compact_checksum( checksum ))){

            // TODO checksum error ICMP?

            // TODO remove debug dump

            printf("udp check failed %x => %x\n", header->checksum, flip_checksum( compact_checksum( checksum )));

            return udp_release_and_return( packet, EINVAL );

        }

    }

    // queue the received packet

    if( ERROR_OCCURRED( dyn_fifo_push( &( ** socket ).received, packet_get_id( packet ), SOCKET_MAX_RECEIVED_SIZE ))){

        return udp_release_and_return( packet, ERROR_CODE );

    }

    // notify the destination socket

    async_msg_5(( ** socket ).phone, NET_SOCKET_RECEIVED, ( ipcarg_t ) ( ** socket ).socket_id, 0, 0, 0, ( ipcarg_t ) fragments );

    return EOK;

}

int udp_message( ipc_callid_t callid, ipc_call_t * call, ipc_call_t * answer, int * answer_count ){

    ERROR_DECLARE;

    packet_t    packet;

    * answer_count = 0;

    switch( IPC_GET_METHOD( * call )){

        case NET_TL_RECEIVED:

            fibril_rwlock_read_lock( & udp_globals.lock );

            if( ! ERROR_OCCURRED( packet_translate( udp_globals.net_phone, & packet, IPC_GET_PACKET( call )))){

                ERROR_CODE = udp_received_msg( IPC_GET_DEVICE( call ), packet, SERVICE_UDP, IPC_GET_ERROR( call ));

            }

            fibril_rwlock_read_unlock( & udp_globals.lock );

            return ERROR_CODE;

        case IPC_M_CONNECT_TO_ME:

            return udp_process_client_messages( callid, * call );

    }

    return ENOTSUP;

}

int udp_process_client_messages( ipc_callid_t callid, ipc_call_t call ){

    int                     res;

    bool                    keep_on_going = true;

    socket_cores_t          local_sockets;

    int                     app_phone = IPC_GET_PHONE( & call );

    struct sockaddr *       addr;

    size_t                  addrlen;

//  fibril_rwlock_t         lock;

    ipc_call_t              answer;

    int                     answer_count;

    /*

     * Accept the connection

     *  - Answer the first IPC_M_CONNECT_ME_TO call.

     */

    ipc_answer_0( callid, EOK );

    // The client connection is only in one fibril and therefore no additional locks are needed.

    socket_cores_initialize( & local_sockets );

//  fibril_rwlock_initialize( & lock );

    while( keep_on_going ){

        // refresh data

        refresh_answer( & answer, & answer_count );

        callid = async_get_call( & call );

//      printf( "message %d\n", IPC_GET_METHOD( * call ));

        switch( IPC_GET_METHOD( call )){

            case IPC_M_PHONE_HUNGUP:

                keep_on_going = false;

                res = EOK;

                break;

            case NET_SOCKET:

//              fibril_rwlock_write_lock( & lock );

                res = socket_create( & local_sockets, app_phone, NULL, SOCKET_SET_SOCKET_ID( answer ));

//              fibril_rwlock_write_unlock( & lock );

                * SOCKET_SET_DATA_FRAGMENT_SIZE( answer ) = MAX_UDP_FRAGMENT_SIZE;

                * SOCKET_SET_HEADER_SIZE( answer ) = sizeof( udp_header_t );

                answer_count = 3;

                break;

            case NET_SOCKET_BIND:

                res = data_receive(( void ** ) & addr, & addrlen );

                if( res == EOK ){

//                  fibril_rwlock_write_lock( & lock );

                    fibril_rwlock_write_lock( & udp_globals.lock );

                    res = socket_bind( & local_sockets, & udp_globals.sockets, SOCKET_GET_SOCKET_ID( call ), addr, addrlen, UDP_FREE_PORTS_START, UDP_FREE_PORTS_END, udp_globals.last_used_port );

                    fibril_rwlock_write_unlock( & udp_globals.lock );

//                  fibril_rwlock_write_unlock( & lock );

                    free( addr );

                }

                break;

            case NET_SOCKET_SENDTO:

                res = data_receive(( void ** ) & addr, & addrlen );

                if( res == EOK ){

//                  fibril_rwlock_read_lock( & lock );

                    fibril_rwlock_read_lock( & udp_globals.lock );

                    res = udp_sendto_message( & local_sockets, SOCKET_GET_SOCKET_ID( call ), addr, addrlen, SOCKET_GET_DATA_FRAGMENTS( call ), SOCKET_GET_DATA_FRAGMENT_SIZE( call ), SOCKET_GET_FLAGS( call ));

                    fibril_rwlock_read_unlock( & udp_globals.lock );

//                  fibril_rwlock_read_unlock( & lock );

                    free( addr );

                }

                break;

            case NET_SOCKET_RECVFROM:

//              fibril_rwlock_read_lock( & lock );

                fibril_rwlock_read_lock( & udp_globals.lock );

                res = udp_recvfrom_message( & local_sockets, SOCKET_GET_SOCKET_ID( call ), SOCKET_GET_FLAGS( call ), & addrlen );

                fibril_rwlock_read_unlock( & udp_globals.lock );

//              fibril_rwlock_read_unlock( & lock );

                if( res > 0 ){

                    * SOCKET_SET_READ_DATA_LENGTH( answer ) = res;

                    * SOCKET_SET_ADDRESS_LENGTH( answer ) = addrlen;

                    answer_count = 2;

                    res = EOK;

                }

                break;

            case NET_SOCKET_CLOSE:

//              fibril_rwlock_write_lock( & lock );

                fibril_rwlock_write_lock( & udp_globals.lock );

                res = socket_destroy( udp_globals.net_phone, SOCKET_GET_SOCKET_ID( call ), & local_sockets, & udp_globals.sockets );

                fibril_rwlock_write_unlock( & udp_globals.lock );

//              fibril_rwlock_write_unlock( & lock );

                break;

            case NET_SOCKET_GETSOCKOPT:

            case NET_SOCKET_SETSOCKOPT:

            default:

                res = ENOTSUP;

                break;

        }

//      printf( "res = %d\n", res );

        answer_call( callid, res, & answer, answer_count );

    }

    // TODO call socket_destroy() on all bound!

    socket_cores_destroy( & local_sockets );

    return EOK;

}

int udp_sendto_message( socket_cores_ref local_sockets, int socket_id, const struct sockaddr * addr, socklen_t addrlen, int fragments, size_t data_fragment_size, int flags ){

    ERROR_DECLARE;

    socket_core_ref         socket;

    packet_t                packet;

    packet_t                next_packet;

    udp_header_ref          header;

    int                     index;

    size_t                  total_length;

    int                     result;

    uint16_t                dest_port;

    uint32_t                checksum;

    ip_pseudo_header_ref    ip_header;

    size_t                  headerlen;

    device_id_t             device_id;

    ERROR_PROPAGATE( tl_get_address_port( addr, addrlen, & dest_port ));

    socket = socket_cores_find( local_sockets, socket_id );

    if( ! socket ) return ENOTSOCK;

    // bind the socket to a random free port if not bound

    while( socket->port <= 0 ){

        // try to find a free port

        fibril_rwlock_read_unlock( & udp_globals.lock );

        fibril_rwlock_write_lock( & udp_globals.lock );

        if( socket->port <= 0 ){

            ERROR_PROPAGATE( socket_bind_free_port( & udp_globals.sockets, socket, UDP_FREE_PORTS_START, UDP_FREE_PORTS_END, udp_globals.last_used_port ));

            // set the next port as the search starting port number

            udp_globals.last_used_port = socket->port;

        }

        fibril_rwlock_write_unlock( & udp_globals.lock );

        fibril_rwlock_read_lock( & udp_globals.lock );

    }

    // TODO do not ask all the time

    ERROR_PROPAGATE( ip_packet_size_req( udp_globals.ip_phone, -1, & udp_globals.packet_dimension.addr_len, & udp_globals.packet_dimension.prefix, & udp_globals.packet_dimension.content, & udp_globals.packet_dimension.suffix ));

    // read the first packet fragment

    result = tl_socket_read_packet_data( udp_globals.net_phone, & packet, sizeof( udp_header_t ), & udp_globals.packet_dimension, addr, addrlen );

    if( result < 0 ) return result;

    total_length = ( size_t ) result;

    if( udp_globals.checksum_computing ){

        checksum = compute_checksum( 0, packet_get_data( packet ), packet_get_data_length( packet ));

    }else{

        checksum = 0;

    }

    // prefix the udp header

    header = PACKET_PREFIX( packet, udp_header_t );

    if( ! header ){

        return udp_release_and_return( packet, ENOMEM );

    }

    bzero( header, sizeof( * header ));

    // read the rest of the packet fragments

    for( index = 1; index < fragments; ++ index ){

        result = tl_socket_read_packet_data( udp_globals.net_phone, & next_packet, 0, & udp_globals.packet_dimension, addr, addrlen );

        if( result < 0 ){

            return udp_release_and_return( packet, result );

        }

        packet = pq_add( packet, next_packet, index, 0 );

        total_length += ( size_t ) result;

        if( udp_globals.checksum_computing ){

            checksum = compute_checksum( checksum, packet_get_data( next_packet ), packet_get_data_length( next_packet ));

        }

    }

    // set the udp header

    header->source_port = htons( socket->port );

    header->destination_port = htons( dest_port );

    header->total_length = htons( total_length + sizeof( udp_header_t ));

    header->checksum = 0;

    if( udp_globals.checksum_computing ){

        if( ERROR_OCCURRED( ip_get_route_req( udp_globals.ip_phone, IPPROTO_UDP, addr, addrlen, & device_id, & ip_header, & headerlen ))){

            return udp_release_and_return( packet, ERROR_CODE );

        }

        if( ERROR_OCCURRED( ip_client_set_pseudo_header_data_length( ip_header, headerlen, total_length + sizeof( udp_header_t )))){

            free( ip_header );

            return udp_release_and_return( packet, ERROR_CODE );

        }

/*//        TODO remove debug dump:

        uint8_t *   data;

        data = ip_header;

        printf( "ip_header:\tlength\t= %d\n\tdata\t= %.2hhX %.2hhX %.2hhX %.2hhX:%.2hhX %.2hhX %.2hhX %.2hhX:%.2hhX %.2hhX %.2hhX %.2hhX\n", headerlen, data[ 0 ], data[ 1 ], data[ 2 ], data[ 3 ], data[ 4 ], data[ 5 ], data[ 6 ], data[ 7 ], data[ 8 ], data[ 9 ], data[ 10 ], data[ 11 ] );

*/      checksum = compute_checksum( checksum, ip_header, headerlen );

        checksum = compute_checksum( checksum, ( uint8_t * ) header, sizeof( * header ));

        header->checksum = htons( flip_checksum( compact_checksum( checksum )));

        free( ip_header );

    }else{

        device_id = -1;

    }

    // prepare the first packet fragment

    if( ERROR_OCCURRED( ip_client_prepare_packet( packet, IPPROTO_UDP, 0, 0, 0, 0 ))){

        return udp_release_and_return( packet, ERROR_CODE );

    }

    // send the packet

    return ip_send_msg( udp_globals.ip_phone, device_id, packet, SERVICE_UDP, 0 );

}

int udp_recvfrom_message( socket_cores_ref local_sockets, int socket_id, int flags, size_t * addrlen ){

    ERROR_DECLARE;

    socket_core_ref socket;

    int             packet_id;

    packet_t        packet;

    udp_header_ref  header;

    struct sockaddr *   addr;

    size_t          length;

    packet_t        next_packet;

    uint8_t *       data;

    size_t          fragments;

    size_t *        lengths;

    size_t          index;

    int             result;

    // find the socket

    socket = socket_cores_find( local_sockets, socket_id );

    if( ! socket ) return ENOTSOCK;

    // get the next received packet

    packet_id = dyn_fifo_value( & socket->received );

    if( packet_id < 0 ) return NO_DATA;

    ERROR_PROPAGATE( packet_translate( udp_globals.net_phone, & packet, packet_id ));

    // get udp header

    data = packet_get_data( packet );

    if( ! data ){

        pq_release( udp_globals.net_phone, packet_id );

        return NO_DATA;

    }

    header = ( udp_header_ref ) data;

    // set the source address port

    result = packet_get_addr( packet, ( uint8_t ** ) & addr, NULL );

    if( ERROR_OCCURRED( tl_set_address_port( addr, result, ntohs( header->source_port )))){

        pq_release( udp_globals.net_phone, packet_id );

        return ERROR_CODE;

    }

    * addrlen = ( size_t ) result;

    // send the source address

    ERROR_PROPAGATE( data_reply( addr, * addrlen ));

    next_packet = pq_next( packet );

    if( ! next_packet ){

        // write all if only one fragment

        ERROR_PROPAGATE( data_reply( data + sizeof( udp_header_t ), packet_get_data_length( packet ) - sizeof( udp_header_t )));

        // store the total length

        length = packet_get_data_length( packet ) - sizeof( udp_header_t );

    }else{

        // count the packet fragments

        fragments = 1;

        next_packet = pq_next( packet );

        while(( next_packet = pq_next( next_packet ))){

            ++ fragments;

        }

        // compute and store the fragment lengths

        lengths = ( size_t * ) malloc( sizeof( size_t ) * fragments + sizeof( size_t ));

        if( ! lengths ) return ENOMEM;

        lengths[ 0 ] = packet_get_data_length( packet ) - sizeof( udp_header_t );

        lengths[ fragments ] = lengths[ 0 ];

        next_packet = pq_next( packet );

        for( index = 1; index < fragments; ++ index ){

            lengths[ index ] = packet_get_data_length( next_packet );

            lengths[ fragments ] += lengths[ index ];

            next_packet = pq_next( packet );

        }while( next_packet );

        // write the fragment lengths

        ERROR_PROPAGATE( data_reply( lengths, sizeof( int ) * ( fragments + 1 )));

        // write the first fragment

        ERROR_PROPAGATE( data_reply( data + sizeof( udp_header_t ), lengths[ 0 ] ));

        next_packet = pq_next( packet );

        // write the rest of the fragments

        for( index = 1; index < fragments; ++ index ){

            ERROR_PROPAGATE( data_reply( packet_get_data( next_packet ), lengths[ index ] ));

            next_packet = pq_next( packet );

        }while( next_packet );

        // store the total length

        length = lengths[ fragments ];

        free( lengths );

    }

    // release the packet

    dyn_fifo_pop( & socket->received );

    pq_release( udp_globals.net_phone, packet_get_id( packet ));

    // return the total length

    return ( int ) length;

}

int udp_release_and_return( packet_t packet, int result ){

    pq_release( udp_globals.net_phone, packet_get_id( packet ));

    return result;

}

/** @}

 */