source: mainline/uspace/lib/c/generic/net/socket_client.c@ 77ad86c

/*
 * 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 libc
 *  @{
 */

/** @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_synch.h>
#include <stdint.h>
#include <stdlib.h>
#include <errno.h>
#include <task.h>
#include <ns.h>
#include <ipc/services.h>
#include <ipc/socket.h>
#include <net/in.h>
#include <net/socket.h>
#include <adt/dynamic_fifo.h>
#include <adt/int_map.h>

/** Initial received packet queue size. */
#define SOCKET_INITIAL_RECEIVED_SIZE    4

/** Maximum received packet queue size. */
#define SOCKET_MAX_RECEIVED_SIZE        0

/** Initial waiting sockets queue size. */
#define SOCKET_INITIAL_ACCEPTED_SIZE    1

/** Maximum waiting sockets queue size. */
#define SOCKET_MAX_ACCEPTED_SIZE        0

/**
 * Maximum number of random attempts to find a new socket identifier before
 * switching to the sequence.
 */
#define SOCKET_ID_TRIES                 100

/** Type definition of the socket specific data.
 * @see socket
 */
typedef struct socket socket_t;

/** 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 session. */
        async_sess_t *sess;
        /** Parent module service. */
        services_t service;

        /**
         * Underlying protocol header size.
         * Sending and receiving optimalization.
         */
        size_t header_size;

        /** Packet data fragment size. Sending optimization. */
        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 session. */
        async_sess_t *tcp_sess;
        /** UDP module session. */
        async_sess_t *udp_sess;

        /** Active sockets. */
        sockets_t *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_sess = NULL,
        .udp_sess = NULL,
        .sockets = NULL,
        .lock = FIBRIL_RWLOCK_INITIALIZER(socket_globals.lock)
};

INT_MAP_IMPLEMENT(sockets, socket_t);

/** Returns the active sockets.
 *
 *  @return             The active sockets.
 */
static sockets_t *socket_get_sockets(void)
{
        if (!socket_globals.sockets) {
                socket_globals.sockets =
                    (sockets_t *) 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;
                }

                srand(task_get_id());
        }

        return socket_globals.sockets;
}

/** Default thread for new connections.
 *
 * @param[in] iid       The initial message identifier.
 * @param[in] icall     The initial message call structure.
 * @param[in] arg       Local argument.
 */
static void socket_connection(ipc_callid_t iid, ipc_call_t * icall, void *arg)
{
        ipc_callid_t callid;
        ipc_call_t call;
        socket_t *socket;
        int rc;

loop:
        callid = async_get_call(&call);

        switch (IPC_GET_IMETHOD(call)) {
        case NET_SOCKET_RECEIVED:
        case NET_SOCKET_ACCEPTED:
        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) {
                        rc = ENOTSOCK;
                        fibril_rwlock_read_unlock(&socket_globals.lock);
                        break;
                }
                
                switch (IPC_GET_IMETHOD(call)) {
                case NET_SOCKET_RECEIVED:
                        fibril_mutex_lock(&socket->receive_lock);
                        /* Push the number of received packet fragments */
                        rc = dyn_fifo_push(&socket->received,
                            SOCKET_GET_DATA_FRAGMENTS(call),
                            SOCKET_MAX_RECEIVED_SIZE);
                        if (rc == EOK) {
                                /* Signal the received packet */
                                fibril_condvar_signal(&socket->receive_signal);
                        }
                        fibril_mutex_unlock(&socket->receive_lock);
                        break;

                case NET_SOCKET_ACCEPTED:
                        /* Push the new socket identifier */
                        fibril_mutex_lock(&socket->accept_lock);
                        rc = dyn_fifo_push(&socket->accepted, 1,
                            SOCKET_MAX_ACCEPTED_SIZE);
                        if (rc == EOK) {
                                /* Signal the accepted socket */
                                fibril_condvar_signal(&socket->accept_signal);
                        }
                        fibril_mutex_unlock(&socket->accept_lock);
                        break;

                default:
                        rc = ENOTSUP;
                }

                if ((SOCKET_GET_DATA_FRAGMENT_SIZE(call) > 0) &&
                    (SOCKET_GET_DATA_FRAGMENT_SIZE(call) !=
                    socket->data_fragment_size)) {
                        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);
                }

                fibril_rwlock_read_unlock(&socket_globals.lock);
                break;

        default:
                rc = ENOTSUP;
        }

        async_answer_0(callid, (sysarg_t) rc);
        goto loop;
}

/** Return the TCP module session.
 *
 * Connect to the TCP module if necessary.
 *
 * @return The TCP module session.
 *
 */
static async_sess_t *socket_get_tcp_sess(void)
{
        if (socket_globals.tcp_sess == NULL)
                socket_globals.tcp_sess = service_bind(SERVICE_TCP,
                    0, 0, SERVICE_TCP, socket_connection);
        
        return socket_globals.tcp_sess;
}

/** Return the UDP module session.
 *
 * Connect to the UDP module if necessary.
 *
 * @return The UDP module session.
 *
 */
static async_sess_t *socket_get_udp_sess(void)
{
        if (socket_globals.udp_sess == NULL)
                socket_globals.udp_sess = service_bind(SERVICE_UDP,
                    0, 0, SERVICE_UDP, socket_connection);
        
        return socket_globals.udp_sess;
}

/** Tries to find a new free socket identifier.
 *
 * @return              The new socket identifier.
 * @return              ELIMIT if there is no socket identifier available.
 */
static int socket_generate_new_id(void)
{
        sockets_t *sockets;
        int socket_id = 0;
        int count;

        sockets = socket_get_sockets();
        count = 0;

        do {
                if (count < SOCKET_ID_TRIES) {
                        socket_id = rand() % INT_MAX;
                        ++count;
                } else if (count == SOCKET_ID_TRIES) {
                        socket_id = 1;
                        ++count;
                /* Only this branch for last_id */
                } else {
                        if (socket_id < INT_MAX) {
                                ++socket_id;
                        } else {
                                return ELIMIT;
                        }
                }
        } while (sockets_find(sockets, socket_id));
        
        return socket_id;
}

/** Initializes a new socket specific data.
 *
 * @param[in,out] socket The socket to be initialized.
 * @param[in] socket_id  The new socket identifier.
 * @param[in] sess       The parent module session.
 * @param[in] service    The parent module service.
 */
static void socket_initialize(socket_t *socket, int socket_id,
    async_sess_t *sess, services_t service)
{
        socket->socket_id = socket_id;
        socket->sess = sess;
        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);
}

/** Creates a new socket.
 *
 * @param[in] domain    The socket protocol family.
 * @param[in] type      Socket type.
 * @param[in] protocol  Socket protocol.
 * @return              The socket identifier on success.
 * @return              EPFNOTSUPPORT if the protocol family is not supported.
 * @return              ESOCKNOTSUPPORT if the socket type is not supported.
 * @return              EPROTONOSUPPORT if the protocol is not supported.
 * @return              ENOMEM if there is not enough memory left.
 * @return              ELIMIT if there was not a free socket identifier found
 *                      this time.
 * @return              Other error codes as defined for the NET_SOCKET message.
 * @return              Other error codes as defined for the
 *                      service_bind() function.
 */
int socket(int domain, int type, int protocol)
{
        socket_t *socket;
        async_sess_t *sess;
        int socket_id;
        services_t service;
        sysarg_t fragment_size;
        sysarg_t header_size;
        int rc;

        /* Find the appropriate service */
        switch (domain) {
        case PF_INET:
                switch (type) {
                case SOCK_STREAM:
                        if (!protocol)
                                protocol = IPPROTO_TCP;

                        switch (protocol) {
                        case IPPROTO_TCP:
                                sess = socket_get_tcp_sess();
                                service = SERVICE_TCP;
                                break;
                        default:
                                return EPROTONOSUPPORT;
                        }

                        break;

                case SOCK_DGRAM:
                        if (!protocol)
                                protocol = IPPROTO_UDP;

                        switch (protocol) {
                        case IPPROTO_UDP:
                                sess = socket_get_udp_sess();
                                service = SERVICE_UDP;
                                break;
                        default:
                                return EPROTONOSUPPORT;
                        }

                        break;

                case SOCK_RAW:
                default:
                        return ESOCKTNOSUPPORT;
                }

                break;

        case PF_INET6:
        default:
                return EPFNOSUPPORT;
        }

        if (sess == NULL)
                return ENOENT;

        /* Create a new socket structure */
        socket = (socket_t *) malloc(sizeof(socket_t));
        if (!socket)
                return ENOMEM;

        bzero(socket, sizeof(*socket));
        fibril_rwlock_write_lock(&socket_globals.lock);

        /* Request a new socket */
        socket_id = socket_generate_new_id();
        if (socket_id <= 0) {
                fibril_rwlock_write_unlock(&socket_globals.lock);
                free(socket);
                return socket_id;
        }
        
        async_exch_t *exch = async_exchange_begin(sess);
        rc = (int) async_req_3_3(exch, NET_SOCKET, socket_id, 0, service, NULL,
            &fragment_size, &header_size);
        async_exchange_end(exch);
        
        if (rc != EOK) {
                fibril_rwlock_write_unlock(&socket_globals.lock);
                free(socket);
                return rc;
        }

        socket->data_fragment_size = (size_t) fragment_size;
        socket->header_size = (size_t) header_size;

        /* Finish the new socket initialization */
        socket_initialize(socket, socket_id, sess, service);
        /* Store the new socket */
        rc = sockets_add(socket_get_sockets(), socket_id, socket);

        fibril_rwlock_write_unlock(&socket_globals.lock);
        if (rc < 0) {
                dyn_fifo_destroy(&socket->received);
                dyn_fifo_destroy(&socket->accepted);
                free(socket);
                
                exch = async_exchange_begin(sess);
                async_msg_3(exch, NET_SOCKET_CLOSE, (sysarg_t) socket_id, 0,
                    service);
                async_exchange_end(exch);
                
                return rc;
        }

        return socket_id;
}

/** Sends message to the socket parent module with specified data.
 *
 * @param[in] socket_id Socket identifier.
 * @param[in] message   The action message.
 * @param[in] arg2      The second message parameter.
 * @param[in] data      The data to be sent.
 * @param[in] datalength The data length.
 * @return              EOK on success.
 * @return              ENOTSOCK if the socket is not found.
 * @return              EBADMEM if the data parameter is NULL.
 * @return              NO_DATA if the datalength parameter is zero (0).
 * @return              Other error codes as defined for the spcific message.
 */
static int
socket_send_data(int socket_id, sysarg_t message, sysarg_t arg2,
    const void *data, size_t datalength)
{
        socket_t *socket;
        aid_t message_id;
        sysarg_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 */
        async_exch_t *exch = async_exchange_begin(socket->sess);
        message_id = async_send_3(exch, message,
            (sysarg_t) socket->socket_id, arg2, socket->service, NULL);
        /* Send the address */
        async_data_write_start(exch, data, datalength);
        async_exchange_end(exch);

        fibril_rwlock_read_unlock(&socket_globals.lock);
        async_wait_for(message_id, &result);
        return (int) result;
}

/** Binds the socket to a port address.
 *
 * @param[in] socket_id Socket identifier.
 * @param[in] my_addr   The port address.
 * @param[in] addrlen   The address length.
 * @return              EOK on success.
 * @return              ENOTSOCK if the socket is not found.
 * @return              EBADMEM if the my_addr parameter is NULL.
 * @return              NO_DATA if the addlen parameter is zero.
 * @return              Other error codes as defined for the NET_SOCKET_BIND
 *                      message.
 */
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);
}

/** Sets the number of connections waiting to be accepted.
 *
 * @param[in] socket_id Socket identifier.
 * @param[in] backlog   The maximum number of waiting sockets to be accepted.
 * @return              EOK on success.
 * @return              EINVAL if the backlog parameter is not positive (<=0).
 * @return              ENOTSOCK if the socket is not found.
 * @return              Other error codes as defined for the NET_SOCKET_LISTEN
 *                      message.
 */
int listen(int socket_id, int backlog)
{
        socket_t *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 */
        async_exch_t *exch = async_exchange_begin(socket->sess);
        result = (int) async_req_3_0(exch, NET_SOCKET_LISTEN,
            (sysarg_t) socket->socket_id, (sysarg_t) backlog, socket->service);
        async_exchange_end(exch);

        fibril_rwlock_read_unlock(&socket_globals.lock);
        return result;
}

/** Accepts waiting socket.
 *
 * Blocks until such a socket exists.
 *
 * @param[in] socket_id Socket identifier.
 * @param[out] cliaddr  The remote client address.
 * @param[in] addrlen   The address length.
 * @return              EOK on success.
 * @return              EBADMEM if the cliaddr or addrlen parameter is NULL.
 * @return              EINVAL if the backlog parameter is not positive (<=0).
 * @return              ENOTSOCK if the socket is not found.
 * @return              Other error codes as defined for the NET_SOCKET_ACCEPT
 *                      message.
 */
int accept(int socket_id, struct sockaddr * cliaddr, socklen_t * addrlen)
{
        socket_t *socket;
        socket_t *new_socket;
        aid_t message_id;
        sysarg_t ipc_result;
        int result;
        ipc_call_t answer;

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

        fibril_rwlock_write_lock(&socket_globals.lock);

        /* Find the socket */
        socket = sockets_find(socket_get_sockets(), socket_id);
        if (!socket) {
                fibril_rwlock_write_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_write_unlock(&socket_globals.lock);
                fibril_condvar_wait(&socket->accept_signal, &socket->accept_lock);
                /* Drop the accept lock to avoid deadlock */
                fibril_mutex_unlock(&socket->accept_lock);
                fibril_rwlock_write_lock(&socket_globals.lock);
                fibril_mutex_lock(&socket->accept_lock);
        }
        -- socket->blocked;

        /* Create a new socket */
        new_socket = (socket_t *) malloc(sizeof(socket_t));
        if (!new_socket) {
                fibril_mutex_unlock(&socket->accept_lock);
                fibril_rwlock_write_unlock(&socket_globals.lock);
                return ENOMEM;
        }
        bzero(new_socket, sizeof(*new_socket));
        socket_id = socket_generate_new_id();
        if (socket_id <= 0) {
                fibril_mutex_unlock(&socket->accept_lock);
                fibril_rwlock_write_unlock(&socket_globals.lock);
                free(new_socket);
                return socket_id;
        }
        socket_initialize(new_socket, socket_id, socket->sess,
            socket->service);
        result = sockets_add(socket_get_sockets(), new_socket->socket_id,
            new_socket);
        if (result < 0) {
                fibril_mutex_unlock(&socket->accept_lock);
                fibril_rwlock_write_unlock(&socket_globals.lock);
                free(new_socket);
                return result;
        }

        /* Request accept */
        async_exch_t *exch = async_exchange_begin(socket->sess);
        message_id = async_send_5(exch, NET_SOCKET_ACCEPT,
            (sysarg_t) socket->socket_id, 0, socket->service, 0,
            new_socket->socket_id, &answer);

        /* Read address */
        async_data_read_start(exch, cliaddr, *addrlen);
        async_exchange_end(exch);
        
        fibril_rwlock_write_unlock(&socket_globals.lock);
        async_wait_for(message_id, &ipc_result);
        result = (int) ipc_result;
        if (result > 0) {
                if (result != socket_id)
                        result = EINVAL;

                /* Dequeue the accepted socket if successful */
                dyn_fifo_pop(&socket->accepted);
                /* Set address length */
                *addrlen = SOCKET_GET_ADDRESS_LENGTH(answer);
                new_socket->data_fragment_size =
                    SOCKET_GET_DATA_FRAGMENT_SIZE(answer);
        } else if (result == ENOTSOCK) {
                /* Empty the queue if no accepted sockets */
                while (dyn_fifo_pop(&socket->accepted) > 0)
                        ;
        }

        fibril_mutex_unlock(&socket->accept_lock);
        return result;
}

/** Connects socket to the remote server.
 *
 * @param[in] socket_id Socket identifier.
 * @param[in] serv_addr The remote server address.
 * @param[in] addrlen   The address length.
 * @return              EOK on success.
 * @return              EBADMEM if the serv_addr parameter is NULL.
 * @return              NO_DATA if the addlen parameter is zero.
 * @return              ENOTSOCK if the socket is not found.
 * @return              Other error codes as defined for the NET_SOCKET_CONNECT
 *                      message.
 */
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);
}

/** Clears and destroys the socket.
 *
 * @param[in] socket    The socket to be destroyed.
 */
static void socket_destroy(socket_t *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, free);
}

/** Closes the socket.
 *
 * @param[in] socket_id Socket identifier.
 * @return              EOK on success.
 * @return              ENOTSOCK if the socket is not found.
 * @return              EINPROGRESS if there is another blocking function in
 *                      progress.
 * @return              Other error codes as defined for the NET_SOCKET_CLOSE
 *                      message.
 */
int closesocket(int socket_id)
{
        socket_t *socket;
        int rc;

        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 */
        async_exch_t *exch = async_exchange_begin(socket->sess);
        rc = (int) async_req_3_0(exch, NET_SOCKET_CLOSE,
            (sysarg_t) socket->socket_id, 0, socket->service);
        async_exchange_end(exch);
        
        if (rc != EOK) {
                fibril_rwlock_write_unlock(&socket_globals.lock);
                return rc;
        }
        /* Free the socket structure */
        socket_destroy(socket);

        fibril_rwlock_write_unlock(&socket_globals.lock);
        return EOK;
}

/** Sends data via the socket to the remote address.
 *
 * Binds the socket to a free port if not already connected/bound.
 *
 * @param[in] message   The action message.
 * @param[in] socket_id Socket identifier.
 * @param[in] data      The data to be sent.
 * @param[in] datalength The data length.
 * @param[in] flags     Various send flags.
 * @param[in] toaddr    The destination address. May be NULL for connected
 *                      sockets.
 * @param[in] addrlen   The address length. Used only if toaddr is not NULL.
 * @return              EOK on success.
 * @return              ENOTSOCK if the socket is not found.
 * @return              EBADMEM if the data or toaddr parameter is NULL.
 * @return              NO_DATA if the datalength or the addrlen parameter is
 *                      zero (0).
 * @return              Other error codes as defined for the NET_SOCKET_SENDTO
 *                      message.
 */
static int
sendto_core(sysarg_t message, int socket_id, const void *data,
    size_t datalength, int flags, const struct sockaddr *toaddr,
    socklen_t addrlen)
{
        socket_t *socket;
        aid_t message_id;
        sysarg_t result;
        size_t fragments;
        ipc_call_t answer;

        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 */
        if (socket->data_fragment_size > 0) {
                fragments = (datalength + socket->header_size) /
                    socket->data_fragment_size;
                if ((datalength + socket->header_size) %
                    socket->data_fragment_size)
                        ++fragments;
        } else {
                fragments = 1;
        }

        /* Request send */
        async_exch_t *exch = async_exchange_begin(socket->sess);
        
        message_id = async_send_5(exch, message,
            (sysarg_t) socket->socket_id,
            (fragments == 1 ? datalength : socket->data_fragment_size),
            socket->service, (sysarg_t) flags, fragments, &answer);

        /* Send the address if given */
        if (!toaddr ||
            (async_data_write_start(exch, toaddr, addrlen) == EOK)) {
                if (fragments == 1) {
                        /* Send all if only one fragment */
                        async_data_write_start(exch, data, datalength);
                } else {
                        /* Send the first fragment */
                        async_data_write_start(exch, 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) {
                                async_data_write_start(exch, data,
                                    socket->data_fragment_size);
                                data = ((const uint8_t *) data) +
                                    socket->data_fragment_size;
                        }

                        /* Send the last fragment */
                        async_data_write_start(exch, data,
                            (datalength + socket->header_size) %
                            socket->data_fragment_size);
                }
        }
        
        async_exchange_end(exch);

        async_wait_for(message_id, &result);

        if ((SOCKET_GET_DATA_FRAGMENT_SIZE(answer) > 0) &&
            (SOCKET_GET_DATA_FRAGMENT_SIZE(answer) !=
            socket->data_fragment_size)) {
                /* Set the data fragment size */
                socket->data_fragment_size =
                    SOCKET_GET_DATA_FRAGMENT_SIZE(answer);
        }

        fibril_rwlock_read_unlock(&socket->sending_lock);
        fibril_rwlock_read_unlock(&socket_globals.lock);
        return (int) result;
}

/** Sends data via the socket.
 *
 * @param[in] socket_id Socket identifier.
 * @param[in] data      The data to be sent.
 * @param[in] datalength The data length.
 * @param[in] flags     Various send flags.
 * @return              EOK on success.
 * @return              ENOTSOCK if the socket is not found.
 * @return              EBADMEM if the data parameter is NULL.
 * @return              NO_DATA if the datalength parameter is zero.
 * @return              Other error codes as defined for the NET_SOCKET_SEND
 *                      message.
 */
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);
}

/** Sends data via the socket to the remote address.
 *
 * Binds the socket to a free port if not already connected/bound.
 *
 * @param[in] socket_id Socket identifier.
 * @param[in] data      The data to be sent.
 * @param[in] datalength The data length.
 * @param[in] flags     Various send flags.
 * @param[in] toaddr    The destination address.
 * @param[in] addrlen   The address length.
 * @return              EOK on success.
 * @return              ENOTSOCK if the socket is not found.
 * @return              EBADMEM if the data or toaddr parameter is NULL.
 * @return              NO_DATA if the datalength or the addrlen parameter is
 *                      zero.
 * @return              Other error codes as defined for the NET_SOCKET_SENDTO
 *                      message.
 */
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);
}

/** Receives data via the socket.
 *
 * @param[in] message   The action message.
 * @param[in] socket_id Socket identifier.
 * @param[out] data     The data buffer to be filled.
 * @param[in] datalength The data length.
 * @param[in] flags     Various receive flags.
 * @param[out] fromaddr The source address. May be NULL for connected sockets.
 * @param[in,out] addrlen The address length. The maximum address length is
 *                      read. The actual address length is set. Used only if
 *                      fromaddr is not NULL.
 * @return              Positive received message size in bytes on success.
 * @return              Zero if no more data (other side closed the connection).
 * @return              ENOTSOCK if the socket is not found.
 * @return              EBADMEM if the data parameter is NULL.
 * @return              NO_DATA if the datalength or addrlen parameter is zero.
 * @return              Other error codes as defined for the spcific message.
 */
static ssize_t
recvfrom_core(sysarg_t message, int socket_id, void *data, size_t datalength,
    int flags, struct sockaddr *fromaddr, socklen_t *addrlen)
{
        socket_t *socket;
        aid_t message_id;
        sysarg_t ipc_result;
        int result;
        size_t fragments;
        size_t *lengths;
        size_t index;
        ipc_call_t answer;
        ssize_t retval;

        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);

                /* Drop the receive lock to avoid deadlock */
                fibril_mutex_unlock(&socket->receive_lock);
                fibril_rwlock_read_lock(&socket_globals.lock);
                fibril_mutex_lock(&socket->receive_lock);
        }
        --socket->blocked;
        fragments = (size_t) result;

        if (fragments == 0) {
                /* No more data, other side has closed the connection. */
                fibril_mutex_unlock(&socket->receive_lock);
                fibril_rwlock_read_unlock(&socket_globals.lock);
                return 0;
        }
        
        async_exch_t *exch = async_exchange_begin(socket->sess);

        /* 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(exch, message,
                    (sysarg_t) socket->socket_id, 0, socket->service,
                    (sysarg_t) flags, &answer);

                /* Read the address if desired */
                if(!fromaddr ||
                    (async_data_read_start(exch, fromaddr,
                    *addrlen) == EOK)) {
                        /* Read the fragment lengths */
                        if (async_data_read_start(exch, lengths,
                            sizeof(int) * (fragments + 1)) == EOK) {
                                if (lengths[fragments] <= datalength) {

                                        /* Read all fragments if long enough */
                                        for (index = 0; index < fragments;
                                            ++index) {
                                                async_data_read_start(exch, data,
                                                    lengths[index]);
                                                data = ((uint8_t *) data) +
                                                    lengths[index];
                                        }
                                }
                        }
                }

                free(lengths);
        } else { /* fragments == 1 */
                /* Request packet data */
                message_id = async_send_4(exch, message,
                    (sysarg_t) socket->socket_id, 0, socket->service,
                    (sysarg_t) flags, &answer);

                /* Read the address if desired */
                if (!fromaddr ||
                    (async_data_read_start(exch, fromaddr, *addrlen) == EOK)) {
                        /* Read all if only one fragment */
                        async_data_read_start(exch, data, datalength);
                }
        }
        
        async_exchange_end(exch);

        async_wait_for(message_id, &ipc_result);
        result = (int) ipc_result;
        if (result == EOK) {
                /* Dequeue the received packet */
                dyn_fifo_pop(&socket->received);
                /* Return read data length */
                retval = SOCKET_GET_READ_DATA_LENGTH(answer);
                /* Set address length */
                if (fromaddr && addrlen)
                        *addrlen = SOCKET_GET_ADDRESS_LENGTH(answer);
        } else {
                retval = (ssize_t) result;
        }

        fibril_mutex_unlock(&socket->receive_lock);
        fibril_rwlock_read_unlock(&socket_globals.lock);
        return retval;
}

/** Receives data via the socket.
 *
 * @param[in] socket_id Socket identifier.
 * @param[out] data     The data buffer to be filled.
 * @param[in] datalength The data length.
 * @param[in] flags     Various receive flags.
 * @return              Positive received message size in bytes on success.
 * @return              Zero if no more data (other side closed the connection).
 * @return              ENOTSOCK if the socket is not found.
 * @return              EBADMEM if the data parameter is NULL.
 * @return              NO_DATA if the datalength parameter is zero.
 * @return              Other error codes as defined for the NET_SOCKET_RECV
 *                      message.
 */
ssize_t 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);
}

/** Receives data via the socket.
 *
 * @param[in] socket_id Socket identifier.
 * @param[out] data     The data buffer to be filled.
 * @param[in] datalength The data length.
 * @param[in] flags     Various receive flags.
 * @param[out] fromaddr The source address.
 * @param[in,out] addrlen The address length. The maximum address length is
 *                      read. The actual address length is set.
 * @return              Positive received message size in bytes on success.
 * @return              Zero if no more data (other side closed the connection).
 * @return              ENOTSOCK if the socket is not found.
 * @return              EBADMEM if the data or fromaddr parameter is NULL.
 * @return              NO_DATA if the datalength or addrlen parameter is zero.
 * @return              Other error codes as defined for the NET_SOCKET_RECVFROM
 *                      message.
 */
ssize_t
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);
}

/** Gets socket option.
 *
 * @param[in] socket_id Socket identifier.
 * @param[in] level     The socket options level.
 * @param[in] optname   The socket option to be get.
 * @param[out] value    The value buffer to be filled.
 * @param[in,out] optlen The value buffer length. The maximum length is read.
 *                      The actual length is set.
 * @return              EOK on success.
 * @return              ENOTSOCK if the socket is not found.
 * @return              EBADMEM if the value or optlen parameter is NULL.
 * @return              NO_DATA if the optlen parameter is zero.
 * @return              Other error codes as defined for the
 *                      NET_SOCKET_GETSOCKOPT message.
 */
int
getsockopt(int socket_id, int level, int optname, void *value, size_t *optlen)
{
        socket_t *socket;
        aid_t message_id;
        sysarg_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 */
        async_exch_t *exch = async_exchange_begin(socket->sess);
        
        message_id = async_send_3(exch, NET_SOCKET_GETSOCKOPT,
            (sysarg_t) socket->socket_id, (sysarg_t) optname, socket->service,
            NULL);

        /* Read the length */
        if (async_data_read_start(exch, optlen,
            sizeof(*optlen)) == EOK) {
                /* Read the value */
                async_data_read_start(exch, value, *optlen);
        }
        
        async_exchange_end(exch);

        fibril_rwlock_read_unlock(&socket_globals.lock);
        async_wait_for(message_id, &result);
        return (int) result;
}

/** Sets socket option.
 *
 * @param[in] socket_id Socket identifier.
 * @param[in] level     The socket options level.
 * @param[in] optname   The socket option to be set.
 * @param[in] value     The value to be set.
 * @param[in] optlen    The value length.
 * @return              EOK on success.
 * @return              ENOTSOCK if the socket is not found.
 * @return              EBADMEM if the value parameter is NULL.
 * @return              NO_DATA if the optlen parameter is zero.
 * @return              Other error codes as defined for the
 *                      NET_SOCKET_SETSOCKOPT message.
 */
int
setsockopt(int socket_id, int level, int optname, const void *value,
    size_t optlen)
{
        /* Send the value */
        return socket_send_data(socket_id, NET_SOCKET_SETSOCKOPT,
            (sysarg_t) optname, value, optlen);
}

/** @}
 */