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/*

 * Copyright (c) 2008 Lukas Mejdrech

 * All rights reserved.

 *

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

 * modification, are permitted provided that the following conditions

 * are met:

 *

 * - Redistributions of source code must retain the above copyright

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

 * - Redistributions in binary form must reproduce the above copyright

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

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

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

 *   derived from this software without specific prior written permission.

 *

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

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

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

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

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

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

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

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

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

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

 */

/** @addtogroup icmp

 *  @{

 */

/** @file

 *  ICMP module implementation.

 *  @see icmp.h

 */

#include <async.h>

#include <atomic.h>

#include <fibril.h>

#include <fibril_sync.h>

#include <stdint.h>

#include <ipc/ipc.h>

#include <ipc/services.h>

#include <sys/types.h>

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

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

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

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

#include "../../include/byteorder.h"

#include "../../include/checksum.h"

#include "../../include/icmp_api.h"

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

#include "../../include/icmp_codes.h"

#include "../../include/icmp_common.h"

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

#include "../../include/il_interface.h"

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

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

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

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

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

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

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

#include "../../tl/tl_messages.h"

#include "icmp.h"

#include "icmp_header.h"

#include "icmp_messages.h"

#include "icmp_module.h"

/** 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   MAX_UINT16

/** Computes the ICMP datagram checksum.

 *  @param header The ICMP datagram header. Input/output parameter.

 *  @param length The total datagram length. Input parameter.

 *  @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 id The message identifier. Input parameter.

 *  @param sequence The message sequence number. Input parameter.

 *  @returns The computed ICMP reply data key.

 */

#define ICMP_GET_REPLY_KEY( id, sequence )  ((( id ) << 16 ) | ( sequence & 0xFFFF ))

/** Type definition of the ICMP reply timeout.

 *  @see icmp_reply_timeout

 */

typedef struct icmp_reply_timeout   icmp_reply_timeout_t;

/** Type definition of the ICMP reply timeout pointer.

 *  @see icmp_reply_timeout

 */

typedef icmp_reply_timeout_t *  icmp_reply_timeout_ref;

/** ICMP reply timeout data.

 *  Used as a timeouting fibril argument.

 *  @see icmp_timeout_for_reply()

 */

struct icmp_reply_timeout{

    /** Reply data key.

     */

    int         reply_key;

    /** Timeout in microseconds.

     */

    suseconds_t timeout;

};

/** 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 packet The received packet. Input/output parameter.

 *  @param receiver The target service. Ignored parameter.

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

 *  @returns EOK on success.

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

 */

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

/** Processes the received ICMP packet.

 *  Notifies the destination socket application.

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

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

 *  @returns EOK on success.

 *  @returns EINVAL if the packet is not valid.

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

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

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

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

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

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

 */

int icmp_process_packet( packet_t packet, services_t error );

/** Processes the client messages.

 *  Remembers the assigned identifier and sequence numbers.

 *  Runs until the client module disconnects.

 *  @param callid The message identifier. Input parameter.

 *  @param call The message parameters. Input parameter.

 *  @returns EOK.

 *  @see icmp_interface.h

 *  @see icmp_api.h

 */

int icmp_process_client_messages( ipc_callid_t callid, ipc_call_t call );

/** Processes the generic client messages.

 *  @param call The message parameters. Input parameter.

 *  @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() function.

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

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

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

 *  @see icmp_interface.h

 */

int icmp_process_message( ipc_call_t * call );

/** Releases the packet and returns the result.

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

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

 *  @returns The result parameter.

 */

int icmp_release_and_return( packet_t packet, int result );

/** 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 occurres.

 *  @param id The message identifier. Input parameter.

 *  @param sequence The message sequence parameter. Input parameter.

 *  @param size The message data length in bytes. Input parameter.

 *  @param timeout The timeout in miliseconds. Input parameter.

 *  @param ttl The time to live. Input parameter.

 *  @param tos The type of service. Input parameter.

 *  @param dont_fragment The value indicating whether the datagram must not be fragmented. Is used as a MTU discovery. Input parameter.

 *  @param addr The target host address. Input parameter.

 *  @param addrlen The torget host address length. Input parameter.

 *  @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 (<=0).

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

 *  @returns EPARTY if there was an internal error.

 */

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 );

/** Prepares the ICMP error packet.

 *  Truncates the original packet if longer than ICMP_KEEP_LENGTH bytes.

 *  Prefixes and returns the ICMP header.

 *  @param packet The original packet. Input/output parameter.

 *  @returns The prefixed ICMP header.

 *  @returns NULL on errors.

 */

icmp_header_ref icmp_prepare_packet( packet_t packet );

/** 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 type The message type. Input parameter.

 *  @param code The message code. Input parameter.

 *  @param packet The message packet to be sent. Input parameter.

 *  @param header The ICMP header. Input parameter.

 *  @param error The error service to be announced. Should be SERVICE_ICMP or zero (0). Input parametr.

 *  @param ttl The time to live. Input parameter.

 *  @param tos The type of service. Input parameter.

 *  @param dont_fragment The value indicating whether the datagram must not be fragmented. Is used as a MTU discovery. Input parameter.

 *  @returns EOK on success.

 *  @returns EPERM if the error message is not allowed.

 */

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 );

/** Tries to set the pending reply result as the received message type.

 *  If the reply data are still present, the reply timeouted and the parent fibril is awaken.

 *  The global lock is not released in this case to be reused by the parent fibril.

 *  Releases the packet.

 *  @param packet The received reply message. Input parameter.

 *  @param header The ICMP message header. Input parameter.

 *  @param type The received reply message type. Input parameter.

 *  @param code The received reply message code. Input parameter.

 *  @returns EOK.

 */

int icmp_process_echo_reply( packet_t packet, icmp_header_ref header, icmp_type_t type, icmp_code_t code );

/** Tries to set the pending reply result as timeouted.

 *  Sleeps the timeout period of time and then tries to obtain and set the pending reply result as timeouted and signals the reply result.

 *  If the reply data are still present, the reply timeouted and the parent fibril is awaken.

 *  The global lock is not released in this case to be reused by the parent fibril.

 *  Should run in a searate fibril.

 *  @param data The icmp_reply_timeout structure. Input parameter.

 *  @returns EOK on success.

 *  @returns EINVAL if the data parameter is NULL.

 */

int icmp_timeout_for_reply( void * data );

/** Assigns a new identifier for the connection.

 *  Fills the echo data parameter with the assigned values.

 *  @param echo_data The echo data to be bound. Input/output parameter.

 *  @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.

 */

int icmp_bind_free_id( icmp_echo_ref echo_data );

/** 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 );

int icmp_echo_msg( int icmp_phone, size_t size, mseconds_t timeout, ip_ttl_t ttl, ip_tos_t tos, int dont_fragment, const struct sockaddr * addr, socklen_t addrlen ){

    icmp_echo_ref   echo_data;

    int             res;

    fibril_rwlock_write_lock( & icmp_globals.lock );

    // use the phone as the echo data index

    echo_data = icmp_echo_data_find( & icmp_globals.echo_data, icmp_phone );

    if( ! echo_data ){

        res = ENOENT;

    }else{

        res = icmp_echo( echo_data->identifier, echo_data->sequence_number, size, timeout, ttl, tos, dont_fragment, addr, addrlen );

        if( echo_data->sequence_number < MAX_UINT16 ){

            ++ echo_data->sequence_number;

        }else{

            echo_data->sequence_number = 0;

        }

    }

    fibril_rwlock_write_unlock( & icmp_globals.lock );

    return res;

}

int icmp_timeout_for_reply( void * data ){

    icmp_reply_ref          reply;

    icmp_reply_timeout_ref  timeout = data;

    if( ! timeout ){

        return EINVAL;

    }

    // sleep the given timeout

    async_usleep( timeout->timeout );

    // lock the globals

    fibril_rwlock_write_lock( & icmp_globals.lock );

    // find the pending reply

    reply = icmp_replies_find( & icmp_globals.replies, timeout->reply_key );

    if( reply ){

        // set the timeout result

        reply->result = ETIMEOUT;

        // notify the main fibril

        fibril_condvar_signal( & reply->condvar );

    }else{

        // unlock only if no reply

        fibril_rwlock_write_unlock( & icmp_globals.lock );

    }

    // release the timeout structure

    free( timeout );

    return EOK;

}

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;

    icmp_reply_timeout_ref  reply_timeout;

    int             result;

    int             index;

    fid_t           fibril;

    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.addr_len, & icmp_globals.prefix, & icmp_globals.content, & icmp_globals.suffix ));

    packet = packet_get_4( icmp_globals.net_phone, size, icmp_globals.addr_len, sizeof( icmp_header_t ) + icmp_globals.prefix, icmp_globals.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 and the reply timeout structures

    reply_timeout = malloc( sizeof( * reply_timeout ));

    if( ! reply_timeout ){

        return icmp_release_and_return( packet, ENOMEM );

    }

    reply = malloc( sizeof( * reply ));

    if( ! reply ){

        free( reply_timeout );

        return icmp_release_and_return( packet, ENOMEM );

    }

    // prepare the timeouting thread

    fibril = fibril_create( icmp_timeout_for_reply, reply_timeout );

    if( ! fibril ){

        free( reply );

        free( reply_timeout );

        return icmp_release_and_return( packet, EPARTY );

    }

    reply_timeout->reply_key = ICMP_GET_REPLY_KEY( header->un.echo.identifier, header->un.echo.sequence_number );

    // timeout in microseconds

    reply_timeout->timeout = timeout * 1000;

    fibril_mutex_initialize( & reply->mutex );

    fibril_mutex_lock( & reply->mutex );

    fibril_condvar_initialize( & reply->condvar );

    // start the timeouting fibril

    fibril_add_ready( fibril );

    index = icmp_replies_add( & icmp_globals.replies, reply_timeout->reply_key, reply );

    if( index < 0 ){

        free( reply );

        return icmp_release_and_return( packet, index );

    }

    // unlock the globals and wait for a 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 a reply

    fibril_condvar_wait( & reply->condvar, & reply->mutex );

    // read the result

    result = reply->result;

    // destroy the reply structure

    fibril_mutex_unlock( & reply->mutex );

    icmp_replies_exclude_index( & icmp_globals.replies, index );

    return result;

}

int icmp_destination_unreachable_msg( 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 );

}

int icmp_source_quench_msg( 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 );

}

int icmp_time_exceeded_msg( 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 );

}

int icmp_parameter_problem_msg( 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 );

}

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;

}

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 );

}

int icmp_connect_module( services_t service ){

    icmp_echo_ref   echo_data;

    icmp_param_t    id;

    int             index;

    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 );

    index = icmp_bind_free_id( echo_data );

    if( index < 0 ){

        free( echo_data );

        fibril_rwlock_write_unlock( & icmp_globals.lock );

        return index;

    }else{

        id = echo_data->identifier;

        fibril_rwlock_write_unlock( & icmp_globals.lock );

        // return the echo data identifier as the ICMP phone

        return id;

    }

}

int icmp_initialize( async_client_conn_t client_connection ){

    ERROR_DECLARE;

    measured_string_t   names[] = {{ "ICMP_ERROR_REPORTING", 20 }, { "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, icmp_received_msg );

    if( icmp_globals.ip_phone < 0 ){

        return icmp_globals.ip_phone;

    }

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

    icmp_globals.prefix += sizeof( icmp_header_t );

    icmp_globals.content -= sizeof( icmp_header_t );

    // get configuration

    icmp_globals.error_reporting = NET_DEFAULT_ICMP_ERROR_REPORTING;

    icmp_globals.echo_replying = NET_DEFAULT_ICMP_ECHO_REPLYING;

    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;

}

int icmp_received_msg( 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;

}

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;

    if( error ){

        switch( error ){

            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 < sizeof( icmp_header_t )) return EINVAL;

    data = packet_get_data( packet );

    if( ! data ) return EINVAL;

    // get icmp header

    header = ( icmp_header_ref ) data;

    // checksum

    if( header->checksum ){

        while( ICMP_CHECKSUM( header, length )){

            // 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 ){

                return icmp_process_echo_reply( packet, header, type, code );

            }else{

                return icmp_process_echo_reply( packet, header, ICMP_ECHO, 0 );

            }

        case ICMP_ECHO:

            if( error ){

                return icmp_process_echo_reply( packet, header, type, code );

            // do not send a reply if disabled

            }else if( icmp_globals.echo_replying ){

                addrlen = packet_get_addr( packet, & src, NULL );

                if(( addrlen > 0 )

                // set both addresses to the source one (avoids the source address deletion before setting the destination one)

                && ( 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;

                }else{

                    return EINVAL;

                }

            }else{

                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;

    }

}

int 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( icmp_globals.net_phone, packet_get_id( packet ));

    // lock the globals

    fibril_rwlock_write_lock( & icmp_globals.lock );

    // find the pending reply

    reply = icmp_replies_find( & icmp_globals.replies, reply_key );

    if( reply ){

        // set the result

        reply->result = type;

        // notify the main fibril

        fibril_condvar_signal( & reply->condvar );

    }else{

        // unlock only if no reply

        fibril_rwlock_write_unlock( & icmp_globals.lock );

    }

    return EOK;

}

int icmp_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( icmp_globals.net_phone, & packet, IPC_GET_PACKET( call )))){

                ERROR_CODE = icmp_received_msg( 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;

}

int icmp_process_client_messages( ipc_callid_t callid, ipc_call_t call ){

    ERROR_DECLARE;

    bool                    keep_on_going = true;

//  fibril_rwlock_t         lock;

    ipc_call_t              answer;

    int                     answer_count;

    size_t                  length;

    struct sockaddr *       addr;

    ipc_callid_t            data_callid;

    icmp_echo_ref           echo_data;

    /*

     * Accept the connection

     *  - Answer the first NET_ICMP_INIT call.

     */

    ipc_answer_0( callid, EOK );

//  fibril_rwlock_initialize( & lock );

    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 );

    ERROR_CODE = icmp_bind_free_id( echo_data );

    fibril_rwlock_write_unlock( & icmp_globals.lock );

    if( ERROR_CODE < 0 ){

        free( echo_data );

        return ERROR_CODE;

    }

    while( keep_on_going ){

        refresh_answer( & answer, & answer_count );

        callid = async_get_call( & call );

        switch( IPC_GET_METHOD( call )){

            case IPC_M_PHONE_HUNGUP:

                keep_on_going = false;

                ERROR_CODE = EOK;

                break;

            case NET_ICMP_ECHO:

//              fibril_rwlock_write_lock( & lock );

                if( ! ipc_data_write_receive( & data_callid, & length )){

                    ERROR_CODE = EINVAL;

                }else{

                    addr = malloc( length );

                    if( ! addr ){

                        ERROR_CODE = ENOMEM;

                    }else{

                        if( ! ERROR_OCCURRED( ipc_data_write_finalize( data_callid, addr, length ))){

                            fibril_rwlock_write_lock( & icmp_globals.lock );

                            ERROR_CODE = 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 < MAX_UINT16 ){

                                ++ echo_data->sequence_number;

                            }else{

                                echo_data->sequence_number = 0;

                            }

                        }

                    }

                }

//              fibril_rwlock_write_unlock( & lock );

                break;

            default:

                ERROR_CODE = icmp_process_message( & call );

        }

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