Subversion Repositories HelenOS

/*

 * Copyright (c) 2009 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 socket

 *  @{

 */

/** @file

 *  Socket application program interface (API) implementation.

 *  @see socket.h for more information.

 *  This is a part of the network application library.

 */

#include <assert.h>

#include <async.h>

#include <fibril_sync.h>

#include <ipc/services.h>

#include "../err.h"

#include "../modules.h"

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

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

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

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

#include "../structures/int_map.h"

#include "socket_messages.h"

/** Initial received packet queue size.

 */

#define SOCKET_INITIAL_RECEIVED_SIZE    4

/** Maximum received packet queue size.

 */

#define SOCKET_MAX_RECEIVED_SIZE        64

/** Initial waiting sockets queue size.

 */

#define SOCKET_INITIAL_ACCEPTED_SIZE    1

/** Maximum waiting sockets queue size.

 */

#define SOCKET_MAX_ACCEPTED_SIZE        64

/** Type definition of the socket specific data.

 *  @see socket

 */

typedef struct socket   socket_t;

/** Type definition of the socket specific data pointer.

 *  @see socket

 */

typedef socket_t *  socket_ref;

/** Socket specific data.

 *  Each socket lock locks only its structure part and any number of them may be locked simultaneously.

 */

struct socket{

    /** Socket identifier.

     */

    int                 socket_id;

    /** Parent module phone.

     */

    int                 phone;

    /** Parent module service.

     */

    services_t          service;

    /** Underlying protocol header size.

     *  Sending and receiving optimalization.

     */

    size_t              header_size;

    /** Packet data fragment size.

     *  Sending optimalization.

     */

    size_t              data_fragment_size;

    /** Sending safety lock.

     *  Locks the header_size and data_fragment_size attributes.

     */

    fibril_rwlock_t     sending_lock;

    /** Received packets queue.

     */

    dyn_fifo_t          received;

    /** Received packets safety lock.

     *  Used for receiving and receive notifications.

     *  Locks the received attribute.

     */

    fibril_mutex_t      receive_lock;

    /** Received packets signaling.

     *  Signaled upon receive notification.

     */

    fibril_condvar_t    receive_signal;

    /** Waiting sockets queue.

     */

    dyn_fifo_t          accepted;

    /** Waiting sockets safety lock.

     *  Used for accepting and accept notifications.

     *  Locks the accepted attribute.

     */

    fibril_mutex_t      accept_lock;

    /** Waiting sockets signaling.

     *  Signaled upon accept notification.

     */

    fibril_condvar_t    accept_signal;

    /** The number of blocked functions called.

     *  Used while waiting for the received packets or accepted sockets.

     */

    int                 blocked;

};

/** Sockets map.

 *  Maps socket identifiers to the socket specific data.

 *  @see int_map.h

 */

INT_MAP_DECLARE( sockets, socket_t );

/** Socket client library global data.

 */

static struct socket_client_globals {

    /** TCP module phone.

     */

    int tcp_phone;

    /** UDP module phone.

     */

    int udp_phone;

    /** Active sockets.

     */

    sockets_ref sockets;

    /** Safety lock.

     *  Write lock is used only for adding or removing sockets.

     *  When locked for writing, no other socket locks need to be locked.

     *  When locked for reading, any other socket locks may be locked.

     *  No socket lock may be locked if this lock is unlocked.

     */

    fibril_rwlock_t lock;

} socket_globals = {

    .tcp_phone = -1,

    .udp_phone = -1,

    .sockets = NULL,

    .lock = {

        .readers = 0,

        .writers = 0,

        .waiters = {

            .prev = & socket_globals.lock.waiters,

            .next = & socket_globals.lock.waiters

        }

    }

};

INT_MAP_IMPLEMENT( sockets, socket_t );

/** Returns the TCP module phone.

 *  Connects to the TCP module if necessary.

 *  @returns The TCP module phone.

 */

static int  socket_get_tcp_phone( void );

/** Returns the UDP module phone.

 *  Connects to the UDP module if necessary.

 *  @returns The UDP module phone.

 */

static int  socket_get_udp_phone( void );

/** Returns the active sockets.

 *  @returns The active sockets.

 */

static sockets_ref  socket_get_sockets( void );

/** Default thread for new connections.

 *  @param iid The initial message identifier. Input parameter.

 *  @param icall The initial message call structure. Input parameter.

 */

void    socket_connection( ipc_callid_t iid, ipc_call_t * icall );

/** Sends message to the socket parent module with specified data.

 *  @param socket_id Socket identifier. Input parameter.

 *  @param message The action message. Input parameter.

 *  @param arg2 The second message parameter. Input parameter.

 *  @param data The data to be sent. Input parameter.

 *  @param datalength The data length. Input parameter.

 *  @returns EOK on success.

 *  @returns ENOTSOCK if the socket is not found.

 *  @returns EBADMEM if the data parameter is NULL.

 *  @returns NO_DATA if the datalength parameter is zero (0).

 *  @returns Other error codes as defined for the spcific message.

 */

int socket_send_data( int socket_id, ipcarg_t message, ipcarg_t arg2, const void * data, size_t datalength );

/** Initializes a new socket specific data.

 *  @param socket The socket to be initialized. Input/output parameter.

 *  @param socket_id The new socket identifier. Input parameter.

 *  @param phone The parent module phone. Input parameter.

 *  @param service The parent module service. Input parameter.

 */

void    socket_initialize( socket_ref socket, int socket_id, int phone, services_t service );

/** Clears and destroys the socket.

 *  @param socket The socket to be destroyed. Input parameter.

 */

void    socket_destroy( socket_ref socket );

/** Receives data via the socket.

 *  @param message The action message. Input parameter.

 *  @param socket_id Socket identifier. Input parameter.

 *  @param data The data buffer to be filled. Output parameter.

 *  @param datalength The data length. Input parameter.

 *  @param flags Various receive flags. Input parameter.

 *  @param fromaddr The source address. May be NULL for connected sockets. Output parameter.

 *  @param addrlen The address length. The maximum address length is read. The actual address length is set. Used only if fromaddr is not NULL. Input/output parameter.

 *  @returns EOK on success.

 *  @returns ENOTSOCK if the socket is not found.

 *  @returns EBADMEM if the data parameter is NULL.

 *  @returns NO_DATA if the datalength or addrlen parameter is zero (0).

 *  @returns Other error codes as defined for the spcific message.

 */

int recvfrom_core( ipcarg_t message, int socket_id, void * data, size_t datalength, int flags, struct sockaddr * fromaddr, socklen_t * addrlen );

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

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

 *  @param message The action message. Input parameter.

 *  @param socket_id Socket identifier. Input parameter.

 *  @param data The data to be sent. Input parameter.

 *  @param datalength The data length. Input parameter.

 *  @param flags Various send flags. Input parameter.

 *  @param toaddr The destination address. May be NULL for connected sockets. Input parameter.

 *  @param addrlen The address length. Used only if toaddr is not NULL. Input parameter.

 *  @returns EOK on success.

 *  @returns ENOTSOCK if the socket is not found.

 *  @returns EBADMEM if the data or toaddr parameter is NULL.

 *  @returns NO_DATA if the datalength or the addrlen parameter is zero (0).

 *  @returns Other error codes as defined for the NET_SOCKET_SENDTO message.

 */

int sendto_core( ipcarg_t message, int socket_id, const void * data, size_t datalength, int flags, const struct sockaddr * toaddr, socklen_t addrlen );

static int socket_get_tcp_phone( void ){

    if( socket_globals.tcp_phone < 0 ){

        socket_globals.tcp_phone = bind_service( SERVICE_TCP, 0, 0, SERVICE_TCP, socket_connection );

    }

    return socket_globals.tcp_phone;

}

static int socket_get_udp_phone( void ){

    if( socket_globals.udp_phone < 0 ){

        socket_globals.udp_phone = bind_service( SERVICE_UDP, 0, 0, SERVICE_UDP, socket_connection );

    }

    return socket_globals.udp_phone;

}

static sockets_ref socket_get_sockets( void ){

    if( ! socket_globals.sockets ){

        socket_globals.sockets = ( sockets_ref ) malloc( sizeof( sockets_t ));

        if( ! socket_globals.sockets ) return NULL;

        if( sockets_initialize( socket_globals.sockets ) != EOK ){

            free( socket_globals.sockets );

            socket_globals.sockets = NULL;

        }

    }

    return socket_globals.sockets;

}

void socket_initialize( socket_ref socket, int socket_id, int phone, services_t service ){

    socket->socket_id = socket_id;

    socket->phone = phone;

    socket->service = service;

    dyn_fifo_initialize( & socket->received, SOCKET_INITIAL_RECEIVED_SIZE );

    dyn_fifo_initialize( & socket->accepted, SOCKET_INITIAL_ACCEPTED_SIZE );

    fibril_mutex_initialize( & socket->receive_lock );

    fibril_condvar_initialize( & socket->receive_signal );

    fibril_mutex_initialize( & socket->accept_lock );

    fibril_condvar_initialize( & socket->accept_signal );

    fibril_rwlock_initialize( & socket->sending_lock );

}

void socket_connection( ipc_callid_t iid, ipc_call_t * icall ){

    ERROR_DECLARE;

    ipc_callid_t    callid;

    ipc_call_t      call;

    socket_ref      socket;

    socket_ref      new_socket;

    while( true ){

        callid = async_get_call( & call );

        switch( IPC_GET_METHOD( call )){

                // TODO remember the data_fragment_size

            case NET_SOCKET_RECEIVED:

                fibril_rwlock_read_lock( & socket_globals.lock );

                // find the socket

                socket = sockets_find( socket_get_sockets(), SOCKET_GET_SOCKET_ID( call ));

                if( ! socket ){

                    ERROR_CODE = ENOTSOCK;

                }else{

                    fibril_mutex_lock( & socket->receive_lock );

                    // push the number of received packet fragments

                    if( ! ERROR_OCCURRED( dyn_fifo_push( & socket->received, SOCKET_GET_DATA_FRAGMENTS( call ), SOCKET_MAX_RECEIVED_SIZE ))){

                        // signal the received packet

                        fibril_condvar_signal( & socket->receive_signal );

                    }

                    fibril_mutex_unlock( & socket->receive_lock );

                }

                fibril_rwlock_read_unlock( & socket_globals.lock );

                break;

            case NET_SOCKET_ACCEPTED:

                fibril_rwlock_read_lock( & socket_globals.lock );

                // find the socket

                socket = sockets_find( socket_get_sockets(), SOCKET_GET_SOCKET_ID( call ));

                if( ! socket ){

                    ERROR_CODE = ENOTSOCK;

                }else{

                    // create a new scoket

                    new_socket = ( socket_ref ) malloc( sizeof( socket_t ));

                    if( ! new_socket ){

                        ERROR_CODE = ENOMEM;

                    }else{

                        bzero( socket, sizeof( * socket ));

                        socket_initialize( new_socket, SOCKET_GET_SOCKET_ID( call ), socket->phone, socket->service );

                        ERROR_CODE = sockets_add( socket_get_sockets(), new_socket->socket_id, new_socket );

                        if( ERROR_CODE < 0 ){

                            free( new_socket );

                        }else{

                            // push the new socket identifier

                            fibril_mutex_lock( & socket->accept_lock );

                            if( ERROR_OCCURRED( dyn_fifo_push( & socket->accepted, new_socket->socket_id, SOCKET_MAX_ACCEPTED_SIZE ))){

                                sockets_exclude( socket_get_sockets(), new_socket->socket_id );

                                free( new_socket );

                            }else{

                                // signal the accepted socket

                                fibril_condvar_signal( & socket->accept_signal );

                            }

                            fibril_mutex_unlock( & socket->accept_lock );

                            ERROR_CODE = EOK;

                        }

                    }

                }

                fibril_rwlock_read_unlock( & socket_globals.lock );

                break;

            // TODO obsolete?

            case NET_SOCKET_DATA_FRAGMENT_SIZE:

                fibril_rwlock_read_lock( & socket_globals.lock );

                // find the socket

                socket = sockets_find( socket_get_sockets(), SOCKET_GET_SOCKET_ID( call ));

                if( ! socket ){

                    ERROR_CODE = ENOTSOCK;

                }else{

                    fibril_rwlock_write_lock( & socket->sending_lock );

                    // set the data fragment size

                    socket->data_fragment_size = SOCKET_GET_DATA_FRAGMENT_SIZE( call );

                    fibril_rwlock_write_unlock( & socket->sending_lock );

                    ERROR_CODE = EOK;

                }

                fibril_rwlock_read_unlock( & socket_globals.lock );

                break;

            default:

                ERROR_CODE = ENOTSUP;

        }

        ipc_answer_0( callid, ( ipcarg_t ) ERROR_CODE );

    }

}

int socket( int domain, int type, int protocol ){

    ERROR_DECLARE;

    socket_ref  socket;

    int         phone;

    int         socket_id;

    services_t  service;

    // find the appropriate service

    switch( domain ){

        case PF_INET:

            switch( type ){

                case SOCK_STREAM:

                    if( ! protocol ) protocol = IPPROTO_TCP;

                    switch( protocol ){

                        case IPPROTO_TCP:

                            phone = socket_get_tcp_phone();

                            service = SERVICE_TCP;

                            break;

                        default:

                            return EPROTONOSUPPORT;

                    }

                    break;

                case SOCK_DGRAM:

                    if( ! protocol ) protocol = IPPROTO_UDP;

                    switch( protocol ){

                        case IPPROTO_UDP:

                            phone = socket_get_udp_phone();

                            service = SERVICE_UDP;

                            break;

                        default:

                            return EPROTONOSUPPORT;

                    }

                    break;

                case SOCK_RAW:

                default:

                    return ESOCKTNOSUPPORT;

            }

            break;

        // TODO IPv6

        default:

            return EPFNOSUPPORT;

    }

    // create a new socket structure

    socket = ( socket_ref ) malloc( sizeof( socket_t ));

    if( ! socket ) return ENOMEM;

    bzero( socket, sizeof( * socket ));

    // request a new socket

    if( ERROR_OCCURRED(( int ) async_req_3_3( phone, NET_SOCKET, 0, 0, service, ( ipcarg_t * ) & socket_id, ( ipcarg_t * ) & socket->data_fragment_size, ( ipcarg_t * ) & socket->header_size ))){

        free( socket );

        return ERROR_CODE;

    }

    // finish the new socket initialization

    socket_initialize( socket, socket_id, phone, service );

    // store the new socket

    fibril_rwlock_write_lock( & socket_globals.lock );

    ERROR_CODE = sockets_add( socket_get_sockets(), socket_id, socket );

    fibril_rwlock_write_unlock( & socket_globals.lock );

    if( ERROR_CODE < 0 ){

        dyn_fifo_destroy( & socket->received );

        dyn_fifo_destroy( & socket->accepted );

        free( socket );

        async_msg_3( phone, NET_SOCKET_CLOSE, ( ipcarg_t ) socket_id, 0, service );

        return ERROR_CODE;

    }

    return socket_id;

}

int socket_send_data( int socket_id, ipcarg_t message, ipcarg_t arg2, const void * data, size_t datalength ){

    socket_ref      socket;

    aid_t           message_id;

    ipcarg_t        result;

    if( ! data ) return EBADMEM;

    if( ! datalength ) return NO_DATA;

    fibril_rwlock_read_lock( & socket_globals.lock );

    // find the socket

    socket = sockets_find( socket_get_sockets(), socket_id );

    if( ! socket ){

        fibril_rwlock_read_unlock( & socket_globals.lock );

        return ENOTSOCK;

    }

    // request the message

    message_id = async_send_3( socket->phone, message, ( ipcarg_t ) socket->socket_id, arg2, socket->service, NULL );

    // send the address

    ipc_data_write_start( socket->phone, data, datalength );

    fibril_rwlock_read_unlock( & socket_globals.lock );

    async_wait_for( message_id, & result );

    return ( int ) result;

}

int bind( int socket_id, const struct sockaddr * my_addr, socklen_t addrlen ){

    if( addrlen <= 0 ) return EINVAL;

    // send the address

    return socket_send_data( socket_id, NET_SOCKET_BIND, 0, my_addr, ( size_t ) addrlen );

}

int listen( int socket_id, int backlog ){

    socket_ref  socket;

    int         result;

    if( backlog <= 0 ) return EINVAL;

    fibril_rwlock_read_lock( & socket_globals.lock );

    // find the socket

    socket = sockets_find( socket_get_sockets(), socket_id );

    if( ! socket ){

        fibril_rwlock_read_unlock( & socket_globals.lock );

        return ENOTSOCK;

    }

    // request listen backlog change

    result = ( int ) async_req_3_0( socket->phone, NET_SOCKET_LISTEN, ( ipcarg_t ) socket->socket_id, ( ipcarg_t ) backlog, socket->service );

    fibril_rwlock_read_unlock( & socket_globals.lock );

    return result;

}

int accept( int socket_id, struct sockaddr * cliaddr, socklen_t * addrlen ){

    socket_ref      socket;

    aid_t           message_id;

    int             result;

    if(( ! cliaddr ) || ( ! addrlen )) return EBADMEM;

    fibril_rwlock_read_lock( & socket_globals.lock );

    // find the socket

    socket = sockets_find( socket_get_sockets(), socket_id );

    if( ! socket ){

        fibril_rwlock_read_unlock( & socket_globals.lock );

        return ENOTSOCK;

    }

    fibril_mutex_lock( & socket->accept_lock );

    // wait for an accepted socket

    ++ socket->blocked;

    while( dyn_fifo_value( & socket->accepted ) <= 0 ){

        fibril_rwlock_read_unlock( & socket_globals.lock );

        fibril_condvar_wait( & socket->accept_signal, & socket->accept_lock );

        fibril_rwlock_read_lock( & socket_globals.lock );

    }

    -- socket->blocked;

    // request accept

    message_id = async_send_3( socket->phone, NET_SOCKET_ACCEPT, ( ipcarg_t ) socket->socket_id, ( ipcarg_t ) dyn_fifo_value( & socket->accepted ), socket->service, NULL );

    // read address

    ipc_data_read_start( socket->phone, cliaddr, * addrlen );

    fibril_rwlock_read_unlock( & socket_globals.lock );

    async_wait_for( message_id, ( ipcarg_t * ) & result );

    if( result > 0 ){

        // dequeue the accepted apcket if successful

        dyn_fifo_pop( & socket->accepted );

    }

    fibril_mutex_unlock( & socket->accept_lock );

    return result;

}

int connect( int socket_id, const struct sockaddr * serv_addr, socklen_t addrlen ){

    if( ! serv_addr ) return EDESTADDRREQ;

    if( ! addrlen ) return EDESTADDRREQ;

    // send the address

    return socket_send_data( socket_id, NET_SOCKET_CONNECT, 0, serv_addr, addrlen );

}

int closesocket( int socket_id ){

    ERROR_DECLARE;

    socket_ref      socket;

    fibril_rwlock_write_lock( & socket_globals.lock );

    socket = sockets_find( socket_get_sockets(), socket_id );

    if( ! socket ){

        fibril_rwlock_write_unlock( & socket_globals.lock );

        return ENOTSOCK;

    }

    if( socket->blocked ){

        fibril_rwlock_write_unlock( & socket_globals.lock );

        return EINPROGRESS;

    }

    // request close

    ERROR_PROPAGATE(( int ) async_req_3_0( socket->phone, NET_SOCKET_CLOSE, ( ipcarg_t ) socket->socket_id, 0, socket->service ));

    // free the socket structure

    socket_destroy( socket );

    fibril_rwlock_write_unlock( & socket_globals.lock );

    return EOK;

}

void socket_destroy( socket_ref socket ){

    int accepted_id;

    // destroy all accepted sockets

    while(( accepted_id = dyn_fifo_pop( & socket->accepted )) >= 0 ){

        socket_destroy( sockets_find( socket_get_sockets(), accepted_id ));

    }

    dyn_fifo_destroy( & socket->received );

    dyn_fifo_destroy( & socket->accepted );

    sockets_exclude( socket_get_sockets(), socket->socket_id );

}

int send( int socket_id, void * data, size_t datalength, int flags ){

    // without the address

    return sendto_core( NET_SOCKET_SEND, socket_id, data, datalength, flags, NULL, 0 );

}

int sendto( int socket_id, const void * data, size_t datalength, int flags, const struct sockaddr * toaddr, socklen_t addrlen ){

    if( ! toaddr ) return EDESTADDRREQ;

    if( ! addrlen ) return EDESTADDRREQ;

    // with the address

    return sendto_core( NET_SOCKET_SENDTO, socket_id, data, datalength, flags, toaddr, addrlen );

}

int sendto_core( ipcarg_t message, int socket_id, const void * data, size_t datalength, int flags, const struct sockaddr * toaddr, socklen_t addrlen ){

    socket_ref      socket;

    aid_t           message_id;

    ipcarg_t        result;

    size_t          fragments;

    if( ! data ) return EBADMEM;

    if( ! datalength ) return NO_DATA;

    fibril_rwlock_read_lock( & socket_globals.lock );

    // find socket

    socket = sockets_find( socket_get_sockets(), socket_id );

    if( ! socket ){

        fibril_rwlock_read_unlock( & socket_globals.lock );

        return ENOTSOCK;

    }

    fibril_rwlock_read_lock( & socket->sending_lock );

    // compute data fragment count

    fragments = ( datalength + socket->header_size ) / socket->data_fragment_size;

    if(( datalength + socket->header_size ) % socket->data_fragment_size ) ++ fragments;

    // request send

    message_id = async_send_5( socket->phone, message, ( ipcarg_t ) socket->socket_id, socket->data_fragment_size, socket->service, ( ipcarg_t ) flags, fragments, NULL );

    // send the address if given

    if(( ! toaddr ) || ( ipc_data_write_start( socket->phone, toaddr, addrlen ) == EOK )){

        if( fragments == 1 ){

            // send all if only one fragment

            ipc_data_write_start( socket->phone, data, datalength );

        }else{

            // send the first fragment

            ipc_data_write_start( socket->phone, data, socket->data_fragment_size - socket->header_size );

            data = (( const uint8_t * ) data ) + socket->data_fragment_size - socket->header_size;

            // send the middle fragments

            while(( -- fragments ) > 1 ){

                ipc_data_write_start( socket->phone, data, socket->data_fragment_size );

                data = (( const uint8_t * ) data ) + socket->data_fragment_size;

            }

            // send the last fragment

            ipc_data_write_start( socket->phone, data, ( datalength + socket->header_size ) % socket->data_fragment_size );

        }

    }

    fibril_rwlock_read_unlock( & socket->sending_lock );

    fibril_rwlock_read_unlock( & socket_globals.lock );

    async_wait_for( message_id, & result );

    return ( int ) result;

}

int recv( int socket_id, void * data, size_t datalength, int flags ){

    // without the address

    return recvfrom_core( NET_SOCKET_RECV, socket_id, data, datalength, flags, NULL, NULL );

}

int recvfrom( int socket_id, void * data, size_t datalength, int flags, struct sockaddr * fromaddr, socklen_t * addrlen ){

    if( ! fromaddr ) return EBADMEM;

    if( ! addrlen ) return NO_DATA;

    // with the address

    return recvfrom_core( NET_SOCKET_RECVFROM, socket_id, data, datalength, flags, fromaddr, addrlen );

}

int recvfrom_core( ipcarg_t message, int socket_id, void * data, size_t datalength, int flags, struct sockaddr * fromaddr, socklen_t * addrlen ){

    socket_ref      socket;

    aid_t           message_id;

    int             result;

    size_t          fragments;

    size_t *        lengths;

    size_t          index;

    ipc_call_t      answer;

    if( ! data ) return EBADMEM;

    if( ! datalength ) return NO_DATA;

    if( fromaddr && ( ! addrlen )) return EINVAL;

    fibril_rwlock_read_lock( & socket_globals.lock );

    // find the socket

    socket = sockets_find( socket_get_sockets(), socket_id );

    if( ! socket ){

        fibril_rwlock_read_unlock( & socket_globals.lock );

        return ENOTSOCK;

    }

    fibril_mutex_lock( & socket->receive_lock );

    // wait for a received packet

    ++ socket->blocked;

    while(( result = dyn_fifo_value( & socket->received )) <= 0 ){

        fibril_rwlock_read_unlock( & socket_globals.lock );

        fibril_condvar_wait( & socket->receive_signal, & socket->receive_lock );

        fibril_rwlock_read_lock( & socket_globals.lock );

    }

    -- socket->blocked;

    fragments = ( size_t ) result;

    // prepare lengths if more fragments

    if( fragments > 1 ){

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

        if( ! lengths ){

            fibril_mutex_unlock( & socket->receive_lock );

            fibril_rwlock_read_unlock( & socket_globals.lock );

            return ENOMEM;

        }

        // request packet data

        message_id = async_send_4( socket->phone, message, ( ipcarg_t ) socket->socket_id, 0, socket->service, ( ipcarg_t ) flags, & answer );

        // read the address if desired

        if(( ! fromaddr ) || ( ipc_data_read_start( socket->phone, fromaddr, * addrlen ) == EOK )){

        // read the fragment lengths

            if( ipc_data_read_start( socket->phone, lengths, sizeof( int ) * ( fragments + 1 )) == EOK ){

                if( lengths[ fragments ] <= datalength ){

                    // read all fragments if long enough

                    for( index = 0; index < fragments; ++ index ){

                        ipc_data_read_start( socket->phone, data, lengths[ index ] );

                        data = (( uint8_t * ) data ) + lengths[ index ];

                    }

                }

            }

        }

        free( lengths );

    }else{

        // request packet data

        message_id = async_send_4( socket->phone, message, ( ipcarg_t ) socket->socket_id, 0, socket->service, ( ipcarg_t ) flags, & answer );

        // read the address if desired

        if(( ! fromaddr ) || ( ipc_data_read_start( socket->phone, fromaddr, * addrlen ) == EOK )){

            // read all if only one fragment

            ipc_data_read_start( socket->phone, data, datalength );

        }

    }

    async_wait_for( message_id, ( ipcarg_t * ) & result );

    // if successful

    if( result == EOK ){

        // dequeue the received packet

        dyn_fifo_pop( & socket->received );

        // return read data length

        result = SOCKET_GET_READ_DATA_LENGTH( answer );

        // set address length

        if( fromaddr && addrlen ) * addrlen = SOCKET_GET_ADDRESS_LENGTH( answer );

    }

    fibril_mutex_unlock( & socket->receive_lock );

    fibril_rwlock_read_unlock( & socket_globals.lock );

    return result;

}

int getsockopt( int socket_id, int level, int optname, void * value, size_t * optlen ){

    socket_ref      socket;

    aid_t           message_id;

    ipcarg_t        result;

    if( !( value && optlen )) return EBADMEM;

    if( !( * optlen )) return NO_DATA;

    fibril_rwlock_read_lock( & socket_globals.lock );

    // find the socket

    socket = sockets_find( socket_get_sockets(), socket_id );

    if( ! socket ){

        fibril_rwlock_read_unlock( & socket_globals.lock );

        return ENOTSOCK;

    }

    // request option value

    message_id = async_send_3( socket->phone, NET_SOCKET_GETSOCKOPT, ( ipcarg_t ) socket->socket_id, ( ipcarg_t ) optname, socket->service, NULL );