source: mainline/uspace/srv/net/tl/icmp/icmp.c@ ba1a2fd

/*
 * 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 icmp
 * @{
 */

/** @file
 * ICMP module implementation.
 * @see icmp.h
 */

#include "icmp.h"
#include "icmp_module.h"

#include <async.h>
#include <atomic.h>
#include <fibril.h>
#include <fibril_synch.h>
#include <stdint.h>
#include <str.h>
#include <ipc/ipc.h>
#include <ipc/services.h>
#include <ipc/net.h>
#include <ipc/tl.h>
#include <ipc/icmp.h>
#include <sys/time.h>
#include <sys/types.h>
#include <byteorder.h>
#include <errno.h>
#include <err.h>

#include <net/socket_codes.h>
#include <net/ip_protocols.h>
#include <net/inet.h>
#include <net/modules.h>
#include <net/icmp_api.h>
#include <net/icmp_codes.h>
#include <net/icmp_common.h>

#include <packet_client.h>
#include <packet_remote.h>
#include <net_checksum.h>
#include <icmp_client.h>
#include <icmp_interface.h>
#include <il_interface.h>
#include <ip_client.h>
#include <ip_interface.h>
#include <net_interface.h>
#include <tl_interface.h>
#include <tl_local.h>
#include <icmp_header.h>

/** ICMP module name. */
#define NAME    "ICMP protocol"

/** Default ICMP error reporting. */
#define NET_DEFAULT_ICMP_ERROR_REPORTING        true

/** Default ICMP echo replying. */
#define NET_DEFAULT_ICMP_ECHO_REPLYING          true

/** Original datagram length in bytes transfered to the error notification
 * message.
 */
#define ICMP_KEEP_LENGTH        8

/** Free identifier numbers pool start. */
#define ICMP_FREE_IDS_START     1

/** Free identifier numbers pool end. */
#define ICMP_FREE_IDS_END       UINT16_MAX

/** Computes the ICMP datagram checksum.
 *
 * @param[in,out] header The ICMP datagram header.
 * @param[in] length    The total datagram length.
 * @returns             The computed checksum.
 */
#define ICMP_CHECKSUM(header, length) \
        htons(ip_checksum((uint8_t *) (header), (length)))

/** An echo request datagrams pattern. */
#define ICMP_ECHO_TEXT          "Hello from HelenOS."

/** Computes an ICMP reply data key.
 *
 * @param[in] id        The message identifier.
 * @param[in] sequence  The message sequence number.
 * @returns             The computed ICMP reply data key.
 */
#define ICMP_GET_REPLY_KEY(id, sequence) \
        (((id) << 16) | (sequence & 0xFFFF))


/** ICMP global data. */
icmp_globals_t  icmp_globals;

INT_MAP_IMPLEMENT(icmp_replies, icmp_reply_t);
INT_MAP_IMPLEMENT(icmp_echo_data, icmp_echo_t);

/** Releases the packet and returns the result.
 *
 * @param[in] packet    The packet queue to be released.
 * @param[in] result    The result to be returned.
 * @returns             The result parameter.
 */
static int icmp_release_and_return(packet_t packet, int result)
{
        pq_release_remote(icmp_globals.net_phone, packet_get_id(packet));
        return result;
}

/** Sends the ICMP message.
 *
 * Sets the message type and code and computes the checksum.
 * Error messages are sent only if allowed in the configuration.
 * Releases the packet on errors.
 *
 * @param[in] type      The message type.
 * @param[in] code      The message code.
 * @param[in] packet    The message packet to be sent.
 * @param[in] header    The ICMP header.
 * @param[in] error     The error service to be announced. Should be
 *                      SERVICE_ICMP or zero.
 * @param[in] ttl       The time to live.
 * @param[in] tos       The type of service.
 * @param[in] dont_fragment The value indicating whether the datagram must not
 *                      be fragmented. Is used as a MTU discovery.
 * @returns             EOK on success.
 * @returns             EPERM if the error message is not allowed.
 */
static int
icmp_send_packet(icmp_type_t type, icmp_code_t code, packet_t packet,
    icmp_header_ref header, services_t error, ip_ttl_t ttl, ip_tos_t tos,
    int dont_fragment)
{
        ERROR_DECLARE;

        // do not send an error if disabled
        if (error && !icmp_globals.error_reporting)
                return icmp_release_and_return(packet, EPERM);

        header->type = type;
        header->code = code;
        header->checksum = 0;
        header->checksum = ICMP_CHECKSUM(header,
            packet_get_data_length(packet));
        if (ERROR_OCCURRED(ip_client_prepare_packet(packet, IPPROTO_ICMP, ttl,
            tos, dont_fragment, 0))) {
                return icmp_release_and_return(packet, ERROR_CODE);
        }

        return ip_send_msg(icmp_globals.ip_phone, -1, packet, SERVICE_ICMP,
            error);
}

/** Prepares the ICMP error packet.
 *
 * Truncates the original packet if longer than ICMP_KEEP_LENGTH bytes.
 * Prefixes and returns the ICMP header.
 *
 * @param[in,out] packet The original packet.
 * @returns The prefixed ICMP header.
 * @returns NULL on errors.
 */
static icmp_header_ref icmp_prepare_packet(packet_t packet)
{
        icmp_header_ref header;
        size_t header_length;
        size_t total_length;

        total_length = packet_get_data_length(packet);
        if (total_length <= 0)
                return NULL;

        header_length = ip_client_header_length(packet);
        if (header_length <= 0)
                return NULL;

        // truncate if longer than 64 bits (without the IP header)
        if ((total_length > header_length + ICMP_KEEP_LENGTH) &&
            (packet_trim(packet, 0,
            total_length - header_length - ICMP_KEEP_LENGTH) != EOK)) {
                return NULL;
        }

        header = PACKET_PREFIX(packet, icmp_header_t);
        if (!header)
                return NULL;

        bzero(header, sizeof(*header));
        return header;
}

/** Requests an echo message.
 *
 * Sends a packet with specified parameters to the target host and waits for
 * the reply upto the given timeout.
 * Blocks the caller until the reply or the timeout occurs.
 *
 * @param[in] id        The message identifier.
 * @param[in] sequence  The message sequence parameter.
 * @param[in] size      The message data length in bytes.
 * @param[in] timeout   The timeout in miliseconds.
 * @param[in] ttl       The time to live.
 * @param[in] tos       The type of service.
 * @param[in] dont_fragment The value indicating whether the datagram must not
 *                      be fragmented. Is used as a MTU discovery.
 * @param[in] addr      The target host address.
 * @param[in] addrlen   The torget host address length.
 * @returns             ICMP_ECHO on success.
 * @returns             ETIMEOUT if the reply has not arrived before the
 *                      timeout.
 * @returns             ICMP type of the received error notification.
 * @returns             EINVAL if the addrlen parameter is less or equal to
 *                      zero.
 * @returns             ENOMEM if there is not enough memory left.
 * @returns             EPARTY if there was an internal error.
 */
static int
icmp_echo(icmp_param_t id, icmp_param_t sequence, size_t size,
    mseconds_t timeout, ip_ttl_t ttl, ip_tos_t tos, int dont_fragment,
    const struct sockaddr * addr, socklen_t addrlen)
{
        ERROR_DECLARE;

        icmp_header_ref header;
        packet_t packet;
        size_t length;
        uint8_t *data;
        icmp_reply_ref reply;
        int reply_key;
        int result;
        int index;

        if (addrlen <= 0)
                return EINVAL;

        length = (size_t) addrlen;
        // TODO do not ask all the time
        ERROR_PROPAGATE(ip_packet_size_req(icmp_globals.ip_phone, -1,
            &icmp_globals.packet_dimension));

        packet = packet_get_4_remote(icmp_globals.net_phone, size,
            icmp_globals.packet_dimension.addr_len,
            ICMP_HEADER_SIZE + icmp_globals.packet_dimension.prefix,
            icmp_globals.packet_dimension.suffix);
        if (!packet)
                return ENOMEM;

        // prepare the requesting packet
        // set the destination address
        if (ERROR_OCCURRED(packet_set_addr(packet, NULL, (const uint8_t *) addr,
            length))) {
                return icmp_release_and_return(packet, ERROR_CODE);
        }

        // allocate space in the packet
        data = (uint8_t *) packet_suffix(packet, size);
        if (!data)
                return icmp_release_and_return(packet, ENOMEM);

        // fill the data
        length = 0;
        while (size > length + sizeof(ICMP_ECHO_TEXT)) {
                memcpy(data + length, ICMP_ECHO_TEXT, sizeof(ICMP_ECHO_TEXT));
                length += sizeof(ICMP_ECHO_TEXT);
        }
        memcpy(data + length, ICMP_ECHO_TEXT, size - length);

        // prefix the header
        header = PACKET_PREFIX(packet, icmp_header_t);
        if (!header)
                return icmp_release_and_return(packet, ENOMEM);

        bzero(header, sizeof(*header));
        header->un.echo.identifier = id;
        header->un.echo.sequence_number = sequence;

        // prepare the reply structure
        reply = malloc(sizeof(*reply));
        if (!reply)
                return icmp_release_and_return(packet, ENOMEM);

        fibril_mutex_initialize(&reply->mutex);
        fibril_mutex_lock(&reply->mutex);
        fibril_condvar_initialize(&reply->condvar);
        reply_key = ICMP_GET_REPLY_KEY(header->un.echo.identifier,
            header->un.echo.sequence_number);
        index = icmp_replies_add(&icmp_globals.replies, reply_key, reply);
        if (index < 0) {
                free(reply);
                return icmp_release_and_return(packet, index);
        }

        // unlock the globals so that we can wait for the reply
        fibril_rwlock_write_unlock(&icmp_globals.lock);

        // send the request
        icmp_send_packet(ICMP_ECHO, 0, packet, header, 0, ttl, tos,
            dont_fragment);

        // wait for the reply
        // timeout in microseconds
        if (ERROR_OCCURRED(fibril_condvar_wait_timeout(&reply->condvar,
            &reply->mutex, timeout * 1000))) {
                result = ERROR_CODE;
        } else {
                // read the result
                result = reply->result;
        }

        // drop the reply mutex before locking the globals again
        fibril_mutex_unlock(&reply->mutex);
        fibril_rwlock_write_lock(&icmp_globals.lock);

        // destroy the reply structure
        icmp_replies_exclude_index(&icmp_globals.replies, index);

        return result;
}

static int
icmp_destination_unreachable_msg_local(int icmp_phone, icmp_code_t code,
    icmp_param_t mtu, packet_t packet)
{
        icmp_header_ref header;

        header = icmp_prepare_packet(packet);
        if (!header)
                return icmp_release_and_return(packet, ENOMEM);

        if (mtu)
                header->un.frag.mtu = mtu;

        return icmp_send_packet(ICMP_DEST_UNREACH, code, packet, header,
            SERVICE_ICMP, 0, 0, 0);
}

static int icmp_source_quench_msg_local(int icmp_phone, packet_t packet)
{
        icmp_header_ref header;

        header = icmp_prepare_packet(packet);
        if (!header)
                return icmp_release_and_return(packet, ENOMEM);

        return icmp_send_packet(ICMP_SOURCE_QUENCH, 0, packet, header,
            SERVICE_ICMP, 0, 0, 0);
}

static int
icmp_time_exceeded_msg_local(int icmp_phone, icmp_code_t code, packet_t packet)
{
        icmp_header_ref header;

        header = icmp_prepare_packet(packet);
        if (!header)
                return icmp_release_and_return(packet, ENOMEM);

        return icmp_send_packet(ICMP_TIME_EXCEEDED, code, packet, header,
            SERVICE_ICMP, 0, 0, 0);
}

static int
icmp_parameter_problem_msg_local(int icmp_phone, icmp_code_t code,
    icmp_param_t pointer, packet_t packet)
{
        icmp_header_ref header;

        header = icmp_prepare_packet(packet);
        if (!header)
                return icmp_release_and_return(packet, ENOMEM);

        header->un.param.pointer = pointer;
        return icmp_send_packet(ICMP_PARAMETERPROB, code, packet, header,
            SERVICE_ICMP, 0, 0, 0);
}

/** Initializes the ICMP module.
 *
 * @param[in] client_connection The client connection processing function. The
 *                      module skeleton propagates its own one.
 * @returns             EOK on success.
 * @returns             ENOMEM if there is not enough memory left.
 */
int icmp_initialize(async_client_conn_t client_connection)
{
        ERROR_DECLARE;

        measured_string_t names[] = {
                {
                        (char *) "ICMP_ERROR_REPORTING",
                        20
                },
                {
                        (char *) "ICMP_ECHO_REPLYING",
                        18
                }
        };
        measured_string_ref configuration;
        size_t count = sizeof(names) / sizeof(measured_string_t);
        char *data;

        fibril_rwlock_initialize(&icmp_globals.lock);
        fibril_rwlock_write_lock(&icmp_globals.lock);
        icmp_replies_initialize(&icmp_globals.replies);
        icmp_echo_data_initialize(&icmp_globals.echo_data);
        icmp_globals.ip_phone = ip_bind_service(SERVICE_IP, IPPROTO_ICMP,
            SERVICE_ICMP, client_connection);
        if (icmp_globals.ip_phone < 0)
                return icmp_globals.ip_phone;

        ERROR_PROPAGATE(ip_packet_size_req(icmp_globals.ip_phone, -1,
            &icmp_globals.packet_dimension));
        icmp_globals.packet_dimension.prefix += ICMP_HEADER_SIZE;
        icmp_globals.packet_dimension.content -= ICMP_HEADER_SIZE;

        icmp_globals.error_reporting = NET_DEFAULT_ICMP_ERROR_REPORTING;
        icmp_globals.echo_replying = NET_DEFAULT_ICMP_ECHO_REPLYING;

        // get configuration
        configuration = &names[0];
        ERROR_PROPAGATE(net_get_conf_req(icmp_globals.net_phone, &configuration,
            count, &data));
        if (configuration) {
                if (configuration[0].value) {
                        icmp_globals.error_reporting =
                            (configuration[0].value[0] == 'y');
                }
                if (configuration[1].value) {
                        icmp_globals.echo_replying =
                            (configuration[1].value[0] == 'y');
                }
                net_free_settings(configuration, data);
        }

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

/** Tries to set the pending reply result as the received message type.
 *
 * If the reply data is not present, the reply timed out and the other fibril
 * is already awake.
 * Releases the packet.
 *
 * @param[in] packet    The received reply message.
 * @param[in] header    The ICMP message header.
 * @param[in] type      The received reply message type.
 * @param[in] code      The received reply message code.
 */
static void 
icmp_process_echo_reply(packet_t packet, icmp_header_ref header,
    icmp_type_t type, icmp_code_t code)
{
        int reply_key;
        icmp_reply_ref reply;

        // compute the reply key
        reply_key = ICMP_GET_REPLY_KEY(header->un.echo.identifier,
            header->un.echo.sequence_number);
        pq_release_remote(icmp_globals.net_phone, packet_get_id(packet));

        fibril_rwlock_write_lock(&icmp_globals.lock);
        // find the pending reply
        reply = icmp_replies_find(&icmp_globals.replies, reply_key);
        if (reply) {
                reply->result = type;
                fibril_condvar_signal(&reply->condvar);
        }
        fibril_rwlock_write_unlock(&icmp_globals.lock);
}

/** Processes the received ICMP packet.
 *
 * Notifies the destination socket application.
 *
 * @param[in,out] packet The received packet.
 * @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.
 */
static int icmp_process_packet(packet_t packet, services_t error)
{
        ERROR_DECLARE;

        size_t length;
        uint8_t *src;
        int addrlen;
        int result;
        void *data;
        icmp_header_ref header;
        icmp_type_t type;
        icmp_code_t code;

        switch (error) {
        case SERVICE_NONE:
                break;
        case SERVICE_ICMP:
                // process error
                result = icmp_client_process_packet(packet, &type, &code, NULL,
                    NULL);
                if (result < 0)
                        return result;
                length = (size_t) result;
                // remove the error header
                ERROR_PROPAGATE(packet_trim(packet, length, 0));
                break;
        default:
                return ENOTSUP;
        }

        // get rid of the ip header
        length = ip_client_header_length(packet);
        ERROR_PROPAGATE(packet_trim(packet, length, 0));

        length = packet_get_data_length(packet);
        if (length <= 0)
                return EINVAL;

        if (length < ICMP_HEADER_SIZE)
                return EINVAL;

        data = packet_get_data(packet);
        if (!data)
                return EINVAL;

        // get icmp header
        header = (icmp_header_ref) data;

        if (header->checksum) {
                while (ICMP_CHECKSUM(header, length) != IP_CHECKSUM_ZERO) {
                        // set the original message type on error notification
                        // type swap observed in Qemu
                        if (error) {
                                switch (header->type) {
                                case ICMP_ECHOREPLY:
                                        header->type = ICMP_ECHO;
                                        continue;
                                }
                        }
                        return EINVAL;
                }
        }

        switch (header->type) {
        case ICMP_ECHOREPLY:
                if (error) 
                        icmp_process_echo_reply(packet, header, type, code);
                else
                        icmp_process_echo_reply(packet, header, ICMP_ECHO, 0);

                return EOK;

        case ICMP_ECHO:
                if (error) {
                        icmp_process_echo_reply(packet, header, type, code);
                        return EOK;
                }
                
                // do not send a reply if disabled
                if (icmp_globals.echo_replying) {
                        addrlen = packet_get_addr(packet, &src, NULL);

                        // set both addresses to the source one (avoids the
                        // source address deletion before setting the
                        // destination one)
                        if ((addrlen > 0) && (packet_set_addr(packet, src, src,
                            (size_t) addrlen) == EOK)) {
                                // send the reply
                                icmp_send_packet(ICMP_ECHOREPLY, 0, packet,
                                    header, 0, 0, 0, 0);
                                return EOK;
                        }

                        return EINVAL;
                }

                return EPERM;

        case ICMP_DEST_UNREACH:
        case ICMP_SOURCE_QUENCH:
        case ICMP_REDIRECT:
        case ICMP_ALTERNATE_ADDR:
        case ICMP_ROUTER_ADV:
        case ICMP_ROUTER_SOL:
        case ICMP_TIME_EXCEEDED:
        case ICMP_PARAMETERPROB:
        case ICMP_CONVERSION_ERROR:
        case ICMP_REDIRECT_MOBILE:
        case ICMP_SKIP:
        case ICMP_PHOTURIS:
                ip_received_error_msg(icmp_globals.ip_phone, -1, packet,
                    SERVICE_IP, SERVICE_ICMP);
                return EOK;

        default:
                return ENOTSUP;
        }
}

/** Processes the received ICMP packet.
 *
 * Is used as an entry point from the underlying IP module.
 * Releases the packet on error.
 *
 * @param device_id     The device identifier. Ignored parameter.
 * @param[in,out] packet The received packet.
 * @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
 *                      icmp_process_packet() function.
 */
static int
icmp_received_msg_local(device_id_t device_id, packet_t packet,
    services_t receiver, services_t error)
{
        ERROR_DECLARE;

        if (ERROR_OCCURRED(icmp_process_packet(packet, error)))
                return icmp_release_and_return(packet, ERROR_CODE);

        return EOK;
}

/** Processes the generic client messages.
 *
 * @param[in] call      The message parameters.
 * @returns             EOK on success.
 * @returns             ENOTSUP if the message is not known.
 * @returns             Other error codes as defined for the packet_translate()
 *                      function.
 * @returns             Other error codes as defined for the
 *                      icmp_destination_unreachable_msg_local() function.
 * @returns             Other error codes as defined for the
 *                      icmp_source_quench_msg_local() function.
 * @returns             Other error codes as defined for the
 *                      icmp_time_exceeded_msg_local() function.
 * @returns             Other error codes as defined for the
 *                      icmp_parameter_problem_msg_local() function.
 *
 * @see icmp_interface.h
 */
static int icmp_process_message(ipc_call_t *call)
{
        ERROR_DECLARE;

        packet_t packet;

        switch (IPC_GET_METHOD(*call)) {
        case NET_ICMP_DEST_UNREACH:
                if (ERROR_NONE(packet_translate_remote(icmp_globals.net_phone,
                    &packet, IPC_GET_PACKET(call)))) {
                        ERROR_CODE = icmp_destination_unreachable_msg_local(0,
                            ICMP_GET_CODE(call), ICMP_GET_MTU(call), packet);
                }
                return ERROR_CODE;
        case NET_ICMP_SOURCE_QUENCH:
                if (ERROR_NONE(packet_translate_remote(icmp_globals.net_phone,
                    &packet, IPC_GET_PACKET(call)))) {
                        ERROR_CODE = icmp_source_quench_msg_local(0, packet);
                }
                return ERROR_CODE;
        case NET_ICMP_TIME_EXCEEDED:
                if (ERROR_NONE(packet_translate_remote(icmp_globals.net_phone,
                    &packet, IPC_GET_PACKET(call)))) {
                        ERROR_CODE = icmp_time_exceeded_msg_local(0,
                            ICMP_GET_CODE(call), packet);
                }
                return ERROR_CODE;
        case NET_ICMP_PARAMETERPROB:
                if (ERROR_NONE(packet_translate_remote(icmp_globals.net_phone,
                    &packet, IPC_GET_PACKET(call)))) {
                        ERROR_CODE = icmp_parameter_problem_msg_local(0,
                            ICMP_GET_CODE(call), ICMP_GET_POINTER(call),
                            packet);
                }
                return ERROR_CODE;
        default:
                return ENOTSUP;
        }
}

/** Assigns a new identifier for the connection.
 *
 * Fills the echo data parameter with the assigned values.
 *
 * @param[in,out] echo_data The echo data to be bound.
 * @returns             Index of the inserted echo data.
 * @returns             EBADMEM if the echo_data parameter is NULL.
 * @returns             ENOTCONN if no free identifier have been found.
 */
static int icmp_bind_free_id(icmp_echo_ref echo_data)
{
        icmp_param_t index;

        if (!echo_data)
                return EBADMEM;

        // from the last used one
        index = icmp_globals.last_used_id;
        do {
                index++;
                // til the range end
                if (index >= ICMP_FREE_IDS_END) {
                        // start from the range beginning
                        index = ICMP_FREE_IDS_START - 1;
                        do {
                                index++;
                                // til the last used one
                                if (index >= icmp_globals.last_used_id) {
                                        // none found
                                        return ENOTCONN;
                                }
                        } while(icmp_echo_data_find(&icmp_globals.echo_data,
                            index) != NULL);

                        // found, break immediately
                        break;
                }
        } while(icmp_echo_data_find(&icmp_globals.echo_data, index) != NULL);

        echo_data->identifier = index;
        echo_data->sequence_number = 0;

        return icmp_echo_data_add(&icmp_globals.echo_data, index, echo_data);
}

/** Processes the client messages.
 *
 * Remembers the assigned identifier and sequence numbers.
 * Runs until the client module disconnects.
 *
 * @param[in] callid    The message identifier.
 * @param[in] call      The message parameters.
 * @returns EOK.
 *
 * @see icmp_interface.h
 * @see icmp_api.h
 */
static int icmp_process_client_messages(ipc_callid_t callid, ipc_call_t call)
{
        ERROR_DECLARE;

        bool keep_on_going = true;
        ipc_call_t answer;
        int answer_count;
        size_t length;
        struct sockaddr *addr;
        ipc_callid_t data_callid;
        icmp_echo_ref echo_data;
        int res;

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

        echo_data = (icmp_echo_ref) malloc(sizeof(*echo_data));
        if (!echo_data)
                return ENOMEM;

        // assign a new identifier
        fibril_rwlock_write_lock(&icmp_globals.lock);
        res = icmp_bind_free_id(echo_data);
        fibril_rwlock_write_unlock(&icmp_globals.lock);
        if (res < 0) {
                free(echo_data);
                return res;
        }

        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_ICMP_ECHO:
                        if (!async_data_write_receive(&data_callid, &length)) {
                                res = EINVAL;
                                break;
                        }
                        
                        addr = malloc(length);
                        if (!addr) {
                                res = ENOMEM;
                                break;
                        }
                        
                        if (ERROR_OCCURRED(async_data_write_finalize(
                            data_callid, addr, length))) {
                                free(addr);
                                res = ERROR_CODE;
                                break;
                        }

                        fibril_rwlock_write_lock(&icmp_globals.lock);
                        res = icmp_echo(echo_data->identifier,
                            echo_data->sequence_number, ICMP_GET_SIZE(call),
                            ICMP_GET_TIMEOUT(call), ICMP_GET_TTL(call),
                            ICMP_GET_TOS(call), ICMP_GET_DONT_FRAGMENT(call),
                            addr, (socklen_t) length);
                        fibril_rwlock_write_unlock(&icmp_globals.lock);

                        free(addr);

                        if (echo_data->sequence_number < UINT16_MAX)
                                echo_data->sequence_number++;
                        else
                                echo_data->sequence_number = 0;

                        break;

                default:
                        res = icmp_process_message(&call);
                }

        }

        // release the identifier
        fibril_rwlock_write_lock(&icmp_globals.lock);
        icmp_echo_data_exclude(&icmp_globals.echo_data, echo_data->identifier);
        fibril_rwlock_write_unlock(&icmp_globals.lock);

        return res;
}

/** Processes the ICMP message.
 *
 * @param[in] callid    The message identifier.
 * @param[in] call      The message parameters.
 * @param[out] answer   The message answer parameters.
 * @param[out] answer_count The last parameter for the actual answer in the
 *                      answer parameter.
 * @returns             EOK on success.
 * @returns             ENOTSUP if the message is not known.
 *
 * @see icmp_interface.h
 * @see IS_NET_ICMP_MESSAGE()
 */
int
icmp_message_standalone(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_NONE(packet_translate_remote(icmp_globals.net_phone,
                    &packet, IPC_GET_PACKET(call)))) {
                        ERROR_CODE =
                            icmp_received_msg_local(IPC_GET_DEVICE(call),
                            packet, SERVICE_ICMP, IPC_GET_ERROR(call));
                }
                return ERROR_CODE;
        
        case NET_ICMP_INIT:
                return icmp_process_client_messages(callid, * call);
        
        default:
                return icmp_process_message(call);
        }

        return ENOTSUP;
}


/** Default thread for new connections.
 *
 * @param[in] iid The initial message identifier.
 * @param[in] icall The initial message call structure.
 *
 */
static void tl_client_connection(ipc_callid_t iid, ipc_call_t *icall)
{
        /*
         * Accept the connection
         *  - Answer the first IPC_M_CONNECT_ME_TO call.
         */
        ipc_answer_0(iid, EOK);
        
        while (true) {
                ipc_call_t answer;
                int answer_count;
                
                /* Clear the answer structure */
                refresh_answer(&answer, &answer_count);
                
                /* Fetch the next message */
                ipc_call_t call;
                ipc_callid_t callid = async_get_call(&call);
                
                /* Process the message */
                int res = tl_module_message_standalone(callid, &call, &answer,
                    &answer_count);
                
                /*
                 * End if told to either by the message or the processing
                 * result.
                 */
                if ((IPC_GET_METHOD(call) == IPC_M_PHONE_HUNGUP) ||
                    (res == EHANGUP))
                        return;
                
                /* Answer the message */
                answer_call(callid, res, &answer, answer_count);
        }
}

/** Starts the module.
 *
 * @returns             EOK on success.
 * @returns             Other error codes as defined for each specific module
 *                      start function.
 */
int main(int argc, char *argv[])
{
        ERROR_DECLARE;
        
        /* Start the module */
        ERROR_PROPAGATE(tl_module_start_standalone(tl_client_connection));
        return EOK;
}

/** @}
 */