source: mainline/uspace/srv/net/tl/udp/udp.c@ 858fc90

/*
 * 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_synch.h>
#include <malloc.h>
#include <stdio.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/checksum.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

/** Default UDP autobind when sending via unbound sockets.
 */
#define NET_DEFAULT_UDP_AUTOBINDING     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.
 *  Locks the global lock and calls udp_process_packet() function.
 *  @param[in] device_id The receiving device identifier.
 *  @param[in,out] packet The received packet queue.
 *  @param receiver The target service. Ignored parameter.
 *  @param[in] error The packet error reporting service. Prefixes the received packet.
 *  @returns EOK on success.
 *  @returns Other error codes as defined for the udp_process_packet() function.
 */
int udp_received_msg(device_id_t device_id, packet_t packet, services_t receiver, services_t error);

/** Processes the received UDP packet queue.
 *  Notifies the destination socket application.
 *  Releases the packet on error or sends an ICMP error notification..
 *  @param[in] device_id The receiving device identifier.
 *  @param[in,out] packet The received packet queue.
 *  @param[in] error The packet error reporting service. Prefixes the received packet.
 *  @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_process_packet(device_id_t device_id, packet_t packet, services_t error);

/** Releases the packet and returns the result.
 *  @param[in] packet The packet queue to be released.
 *  @param[in] result The result to be returned.
 *  @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[in] callid The message identifier.
 *  @param[in] call The message parameters.
 *  @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[in,out] local_sockets The application local sockets.
 *  @param[in] socket_id Socket identifier.
 *  @param[in] addr The destination address.
 *  @param[in] addrlen The address length.
 *  @param[in] fragments The number of data fragments.
 *  @param[out] data_fragment_size The data fragment size in bytes.
 *  @param[in] flags Various send flags.
 *  @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[in] local_sockets The application local sockets.
 *  @param[in] socket_id Socket identifier.
 *  @param[in] flags Various receive flags.
 *  @param[out] addrlen The source address length.
 *  @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[] = {{str_dup("UDP_CHECKSUM_COMPUTING"), 22}, {str_dup("UDP_AUTOBINDING"), 15}};
        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, ICMP_CONNECT_TIMEOUT);
        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;
        }
        // read default packet dimensions
        ERROR_PROPAGATE(ip_packet_size_req(udp_globals.ip_phone, -1, &udp_globals.packet_dimension));
        ERROR_PROPAGATE(socket_ports_initialize(&udp_globals.sockets));
        if(ERROR_OCCURRED(packet_dimensions_initialize(&udp_globals.dimensions))){
                socket_ports_destroy(&udp_globals.sockets);
                return ERROR_CODE;
        }
        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;
        udp_globals.autobinding = NET_DEFAULT_UDP_AUTOBINDING;
        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');
                }
                if(configuration[1].value){
                        udp_globals.autobinding = (configuration[1].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){
        int result;

        fibril_rwlock_write_lock(&udp_globals.lock);
        result = udp_process_packet(device_id, packet, error);
        if(result != EOK){
                fibril_rwlock_write_unlock(&udp_globals.lock);
        }

        return result;
}

int udp_process_packet(device_id_t device_id, packet_t packet, services_t error){
        ERROR_DECLARE;

        size_t length;
        size_t offset;
        int result;
        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;
        packet_dimension_ref packet_dimension;

        if(error){
                switch(error){
                        case SERVICE_ICMP:
                                // ignore error
                                // length = icmp_client_header_length(packet);
                                // process error
                                result = icmp_client_process_packet(packet, &type, &code, NULL, NULL);
                                if(result < 0){
                                        return udp_release_and_return(packet, result);
                                }
                                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 < UDP_HEADER_SIZE + offset){
                return udp_release_and_return(packet, NO_DATA);
        }

        // trim all but UDP header
        if(ERROR_OCCURRED(packet_trim(packet, offset, 0))){
                return udp_release_and_return(packet, ERROR_CODE);
        }

        // get udp header
        header = (udp_header_ref) packet_get_data(packet);
        if(! header){
                return udp_release_and_return(packet, NO_DATA);
        }
        // find the destination socket
        socket = socket_port_find(&udp_globals.sockets, ntohs(header->destination_port), SOCKET_MAP_KEY_LISTENING, 0);
        if(! socket){
                if(tl_prepare_icmp_packet(udp_globals.net_phone, udp_globals.icmp_phone, packet, error) == EOK){
                        icmp_destination_unreachable_msg(udp_globals.icmp_phone, ICMP_PORT_UNREACH, 0, packet);
                }
                return EADDRNOTAVAIL;
        }

        // 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)) != IP_CHECKSUM_ZERO){
                        if(tl_prepare_icmp_packet(udp_globals.net_phone, udp_globals.icmp_phone, packet, error) == EOK){
                                // checksum error ICMP
                                icmp_parameter_problem_msg(udp_globals.icmp_phone, ICMP_PARAM_POINTER, ((size_t) ((void *) &header->checksum)) - ((size_t) ((void *) header)), packet);
                        }
                        return EINVAL;
                }
        }

        // queue the received packet
        if(ERROR_OCCURRED(dyn_fifo_push(&socket->received, packet_get_id(packet), SOCKET_MAX_RECEIVED_SIZE))
                || ERROR_OCCURRED(tl_get_ip_packet_dimension(udp_globals.ip_phone, &udp_globals.dimensions, device_id, &packet_dimension))){
                return udp_release_and_return(packet, ERROR_CODE);
        }

        // notify the destination socket
        fibril_rwlock_write_unlock(&udp_globals.lock);
        async_msg_5(socket->phone, NET_SOCKET_RECEIVED, (ipcarg_t) socket->socket_id, packet_dimension->content, 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:
                        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));
                        }
                        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;
        ipc_call_t answer;
        int answer_count;
        packet_dimension_ref packet_dimension;

        /*
         * Accept the connection
         *  - Answer the first IPC_M_CONNECT_TO_ME call.
         */
        res = EOK;
        answer_count = 0;

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

        socket_cores_initialize(&local_sockets);

        while(keep_on_going){

                // answer the call
                answer_call(callid, res, &answer, answer_count);

                // refresh data
                refresh_answer(&answer, &answer_count);

                // get the next call
                callid = async_get_call(&call);

                // process the call
                switch(IPC_GET_METHOD(call)){
                        case IPC_M_PHONE_HUNGUP:
                                keep_on_going = false;
                                res = EHANGUP;
                                break;
                        case NET_SOCKET:
                                *SOCKET_SET_SOCKET_ID(answer) = SOCKET_GET_SOCKET_ID(call);
                                res = socket_create(&local_sockets, app_phone, NULL, SOCKET_SET_SOCKET_ID(answer));
                                if(res == EOK){
                                        if(tl_get_ip_packet_dimension(udp_globals.ip_phone, &udp_globals.dimensions, DEVICE_INVALID_ID, &packet_dimension) == EOK){
                                                *SOCKET_SET_DATA_FRAGMENT_SIZE(answer) = packet_dimension->content;
                                        }
//                                      *SOCKET_SET_DATA_FRAGMENT_SIZE(answer) = MAX_UDP_FRAGMENT_SIZE;
                                        *SOCKET_SET_HEADER_SIZE(answer) = UDP_HEADER_SIZE;
                                        answer_count = 3;
                                }
                                break;
                        case NET_SOCKET_BIND:
                                res = data_receive((void **) &addr, &addrlen);
                                if(res == EOK){
                                        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);
                                        free(addr);
                                }
                                break;
                        case NET_SOCKET_SENDTO:
                                res = data_receive((void **) &addr, &addrlen);
                                if(res == EOK){
                                        fibril_rwlock_write_lock(&udp_globals.lock);
                                        res = udp_sendto_message(&local_sockets, SOCKET_GET_SOCKET_ID(call), addr, addrlen, SOCKET_GET_DATA_FRAGMENTS(call), SOCKET_SET_DATA_FRAGMENT_SIZE(answer), SOCKET_GET_FLAGS(call));
                                        if(res != EOK){
                                                fibril_rwlock_write_unlock(&udp_globals.lock);
                                        }else{
                                                answer_count = 2;
                                        }
                                        free(addr);
                                }
                                break;
                        case NET_SOCKET_RECVFROM:
                                fibril_rwlock_write_lock(&udp_globals.lock);
                                res = udp_recvfrom_message(&local_sockets, SOCKET_GET_SOCKET_ID(call), SOCKET_GET_FLAGS(call), &addrlen);
                                fibril_rwlock_write_unlock(&udp_globals.lock);
                                if(res > 0){
                                        *SOCKET_SET_READ_DATA_LENGTH(answer) = res;
                                        *SOCKET_SET_ADDRESS_LENGTH(answer) = addrlen;
                                        answer_count = 3;
                                        res = EOK;
                                }
                                break;
                        case NET_SOCKET_CLOSE:
                                fibril_rwlock_write_lock(&udp_globals.lock);
                                res = socket_destroy(udp_globals.net_phone, SOCKET_GET_SOCKET_ID(call), &local_sockets, &udp_globals.sockets, NULL);
                                fibril_rwlock_write_unlock(&udp_globals.lock);
                                break;
                        case NET_SOCKET_GETSOCKOPT:
                        case NET_SOCKET_SETSOCKOPT:
                        default:
                                res = ENOTSUP;
                                break;
                }
        }

        // release the application phone
        ipc_hangup(app_phone);

        // release all local sockets
        socket_cores_release(udp_globals.net_phone, &local_sockets, &udp_globals.sockets, NULL);

        return res;
}

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;
        packet_dimension_ref packet_dimension;

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

        socket = socket_cores_find(local_sockets, socket_id);
        if(! socket){
                return ENOTSOCK;
        }

        if((socket->port <= 0) && udp_globals.autobinding){
                // bind the socket to a random free port if not bound
//              do{
                        // try to find a free port
//                      fibril_rwlock_read_unlock(&udp_globals.lock);
//                      fibril_rwlock_write_lock(&udp_globals.lock);
                        // might be changed in the meantime
//                      if(socket->port <= 0){
                                if(ERROR_OCCURRED(socket_bind_free_port(&udp_globals.sockets, socket, UDP_FREE_PORTS_START, UDP_FREE_PORTS_END, udp_globals.last_used_port))){
//                                      fibril_rwlock_write_unlock(&udp_globals.lock);
//                                      fibril_rwlock_read_lock(&udp_globals.lock);
                                        return ERROR_CODE;
                                }
                                // 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);
                        // might be changed in the meantime
//              }while(socket->port <= 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);
                }
                // get the device packet dimension
//              ERROR_PROPAGATE(tl_get_ip_packet_dimension(udp_globals.ip_phone, &udp_globals.dimensions, device_id, &packet_dimension));
        }
//      }else{
                // do not ask all the time
                ERROR_PROPAGATE(ip_packet_size_req(udp_globals.ip_phone, -1, &udp_globals.packet_dimension));
                packet_dimension = &udp_globals.packet_dimension;
//      }

        // read the first packet fragment
        result = tl_socket_read_packet_data(udp_globals.net_phone, &packet, UDP_HEADER_SIZE, 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, packet_dimension, addr, addrlen);
                if(result < 0){
                        return udp_release_and_return(packet, result);
                }
                if(ERROR_OCCURRED(pq_add(&packet, next_packet, index, 0))){
                        return udp_release_and_return(packet, ERROR_CODE);
                }
                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 > 0) ? socket->port : 0);
        header->destination_port = htons(dest_port);
        header->total_length = htons(total_length + sizeof(*header));
        header->checksum = 0;
        if(udp_globals.checksum_computing){
                // update the pseudo header
                if(ERROR_OCCURRED(ip_client_set_pseudo_header_data_length(ip_header, headerlen, total_length + UDP_HEADER_SIZE))){
                        free(ip_header);
                        return udp_release_and_return(packet, ERROR_CODE);
                }
                // finish the checksum computation
                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 = DEVICE_INVALID_ID;
        }
        // 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
        fibril_rwlock_write_unlock(&udp_globals.lock);
        ip_send_msg(udp_globals.ip_phone, device_id, packet, SERVICE_UDP, 0);
        return EOK;
}

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;
        uint8_t * data;
        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));

        // trim the header
        ERROR_PROPAGATE(packet_trim(packet, UDP_HEADER_SIZE, 0));

        // reply the packets
        ERROR_PROPAGATE(socket_reply_packets(packet, &length));

        // 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;
}

/** @}
 */