source: mainline/uspace/srv/net/nil/eth/eth.c@ bbf159a

/*
 * Copyright (c) 2009 Lukas Mejdrech
 * Copyright (c) 2011 Radim Vansa
 * 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 eth
 *  @{
 */

/** @file
 *  Ethernet module implementation.
 *  @see eth.h
 */

#include <assert.h>
#include <async.h>
#include <malloc.h>
#include <mem.h>
#include <stdio.h>
#include <byteorder.h>
#include <str.h>
#include <errno.h>
#include <ipc/nil.h>
#include <ipc/net.h>
#include <ipc/services.h>
#include <net/modules.h>
#include <net_checksum.h>
#include <ethernet_lsap.h>
#include <ethernet_protocols.h>
#include <protocol_map.h>
#include <net/device.h>
#include <net_interface.h>
#include <il_remote.h>
#include <adt/measured_strings.h>
#include <packet_client.h>
#include <packet_remote.h>
#include <device/nic.h>
#include <nil_skel.h>
#include "eth.h"

/** The module name. */
#define NAME  "eth"

/** Reserved packet prefix length. */
#define ETH_PREFIX \
        (sizeof(eth_header_t) + sizeof(eth_header_lsap_t) + \
            sizeof(eth_header_snap_t))

/** Reserved packet suffix length. */
#define ETH_SUFFIX  (sizeof(eth_fcs_t))

/** Maximum packet content length. */
#define ETH_MAX_CONTENT  1500u

/** Minimum packet content length. */
#define ETH_MIN_CONTENT  46u

/** Maximum tagged packet content length. */
#define ETH_MAX_TAGGED_CONTENT(flags) \
        (ETH_MAX_CONTENT - \
            ((IS_8023_2_LSAP(flags) || IS_8023_2_SNAP(flags)) ? \
            sizeof(eth_header_lsap_t) : 0) - \
            (IS_8023_2_SNAP(flags) ? sizeof(eth_header_snap_t) : 0))

/** Minimum tagged packet content length. */
#define ETH_MIN_TAGGED_CONTENT(flags) \
        (ETH_MIN_CONTENT - \
            ((IS_8023_2_LSAP(flags) || IS_8023_2_SNAP(flags)) ? \
            sizeof(eth_header_lsap_t) : 0) - \
            (IS_8023_2_SNAP(flags) ? sizeof(eth_header_snap_t) : 0))

/** Dummy flag shift value. */
#define ETH_DUMMY_SHIFT  0

/** Mode flag shift value. */
#define ETH_MODE_SHIFT  1

/** Dummy device flag.
 * Preamble and FCS are mandatory part of the packets.
 */
#define ETH_DUMMY  (1 << ETH_DUMMY_SHIFT)

/** Returns the dummy flag.
 * @see ETH_DUMMY
 */
#define IS_DUMMY(flags)  ((flags) & ETH_DUMMY)

/** Device mode flags.
 * @see ETH_DIX
 * @see ETH_8023_2_LSAP
 * @see ETH_8023_2_SNAP
 */
#define ETH_MODE_MASK  (3 << ETH_MODE_SHIFT)

/** DIX Ethernet mode flag. */
#define ETH_DIX  (1 << ETH_MODE_SHIFT)

/** Return whether the DIX Ethernet mode flag is set.
 *
 * @param[in] flags Ethernet flags.
 * @see ETH_DIX
 *
 */
#define IS_DIX(flags)  (((flags) & ETH_MODE_MASK) == ETH_DIX)

/** 802.3 + 802.2 + LSAP mode flag. */
#define ETH_8023_2_LSAP  (2 << ETH_MODE_SHIFT)

/** Return whether the 802.3 + 802.2 + LSAP mode flag is set.
 *
 * @param[in] flags Ethernet flags.
 * @see ETH_8023_2_LSAP
 *
 */
#define IS_8023_2_LSAP(flags)  (((flags) & ETH_MODE_MASK) == ETH_8023_2_LSAP)

/** 802.3 + 802.2 + LSAP + SNAP mode flag. */
#define ETH_8023_2_SNAP  (3 << ETH_MODE_SHIFT)

/** Return whether the 802.3 + 802.2 + LSAP + SNAP mode flag is set.
 *
 * @param[in] flags Ethernet flags.
 * @see ETH_8023_2_SNAP
 *
 */
#define IS_8023_2_SNAP(flags)  (((flags) & ETH_MODE_MASK) == ETH_8023_2_SNAP)

/** Type definition of the ethernet address type.
 * @see eth_addr_type
 */
typedef enum eth_addr_type eth_addr_type_t;

/** Ethernet address type. */
enum eth_addr_type {
        /** Local address. */
        ETH_LOCAL_ADDR,
        /** Broadcast address. */
        ETH_BROADCAST_ADDR
};

/** Ethernet module global data. */
eth_globals_t eth_globals;

DEVICE_MAP_IMPLEMENT(eth_devices, eth_device_t);
INT_MAP_IMPLEMENT(eth_protos, eth_proto_t);

int nil_device_state_msg_local(nic_device_id_t device_id, sysarg_t state)
{
        int index;
        eth_proto_t *proto;

        fibril_rwlock_read_lock(&eth_globals.protos_lock);
        for (index = eth_protos_count(&eth_globals.protos) - 1; index >= 0;
            index--) {
                proto = eth_protos_get_index(&eth_globals.protos, index);
                if ((proto) && (proto->sess)) {
                        il_device_state_msg(proto->sess, device_id, state,
                            proto->service);
                }
        }
        fibril_rwlock_read_unlock(&eth_globals.protos_lock);
        
        return EOK;
}

int nil_initialize(async_sess_t *sess)
{
        int rc;

        fibril_rwlock_initialize(&eth_globals.devices_lock);
        fibril_rwlock_initialize(&eth_globals.protos_lock);
        
        fibril_rwlock_write_lock(&eth_globals.devices_lock);
        fibril_rwlock_write_lock(&eth_globals.protos_lock);
        
        eth_globals.net_sess = sess;
        memcpy(eth_globals.broadcast_addr, "\xFF\xFF\xFF\xFF\xFF\xFF",
                        ETH_ADDR);

        rc = eth_devices_initialize(&eth_globals.devices);
        if (rc != EOK) {
                free(eth_globals.broadcast_addr);
                goto out;
        }

        rc = eth_protos_initialize(&eth_globals.protos);
        if (rc != EOK) {
                free(eth_globals.broadcast_addr);
                eth_devices_destroy(&eth_globals.devices, free);
        }
        
out:
        fibril_rwlock_write_unlock(&eth_globals.protos_lock);
        fibril_rwlock_write_unlock(&eth_globals.devices_lock);
        
        return rc;
}

/** Register new device or updates the MTU of an existing one.
 *
 * Determine the device local hardware address.
 *
 * @param[in] device_id New device identifier.
 * @param[in] handle    Device driver handle.
 * @param[in] mtu       Device maximum transmission unit.
 *
 * @return EOK on success.
 * @return EEXIST if the device with the different service exists.
 * @return ENOMEM if there is not enough memory left.
 *
 */
static int eth_device_message(nic_device_id_t device_id, devman_handle_t handle,
    size_t mtu)
{
        eth_device_t *device;
        int index;
        measured_string_t names[2] = {
                {
                        (uint8_t *) "ETH_MODE",
                        8
                },
                {
                        (uint8_t *) "ETH_DUMMY",
                        9
                }
        };
        measured_string_t *configuration;
        size_t count = sizeof(names) / sizeof(measured_string_t);
        uint8_t *data;
        eth_proto_t *proto;
        int rc;

        fibril_rwlock_write_lock(&eth_globals.devices_lock);
        /* An existing device? */
        device = eth_devices_find(&eth_globals.devices, device_id);
        if (device) {
                if (device->handle != handle) {
                        printf("Device %d already exists\n", device->device_id);
                        fibril_rwlock_write_unlock(&eth_globals.devices_lock);
                        return EEXIST;
                }
                
                /* Update mtu */
                if ((mtu > 0) && (mtu <= ETH_MAX_TAGGED_CONTENT(device->flags)))
                        device->mtu = mtu;
                else
                        device->mtu = ETH_MAX_TAGGED_CONTENT(device->flags);
                
                printf("Device %d already exists:\tMTU\t= %zu\n",
                    device->device_id, device->mtu);
                fibril_rwlock_write_unlock(&eth_globals.devices_lock);
                
                /* Notify all upper layer modules */
                fibril_rwlock_read_lock(&eth_globals.protos_lock);
                for (index = 0; index < eth_protos_count(&eth_globals.protos);
                    index++) {
                        proto = eth_protos_get_index(&eth_globals.protos,
                            index);
                        if (proto->sess) {
                                il_mtu_changed_msg(proto->sess,
                                    device->device_id, device->mtu,
                                    proto->service);
                        }
                }

                fibril_rwlock_read_unlock(&eth_globals.protos_lock);
                return EOK;
        }
        
        /* Create a new device */
        device = (eth_device_t *) malloc(sizeof(eth_device_t));
        if (!device)
                return ENOMEM;

        device->device_id = device_id;
        device->handle = handle;
        device->flags = 0;
        if ((mtu > 0) && (mtu <= ETH_MAX_TAGGED_CONTENT(device->flags)))
                device->mtu = mtu;
        else
                device->mtu = ETH_MAX_TAGGED_CONTENT(device->flags);

        configuration = &names[0];
        rc = net_get_device_conf_req(eth_globals.net_sess, device->device_id,
            &configuration, count, &data);
        if (rc != EOK) {
                fibril_rwlock_write_unlock(&eth_globals.devices_lock);
                free(device);
                return rc;
        }

        if (configuration) {
                if (!str_lcmp((char *) configuration[0].value, "DIX",
                    configuration[0].length)) {
                        device->flags |= ETH_DIX;
                } else if(!str_lcmp((char *) configuration[0].value, "8023_2_LSAP",
                    configuration[0].length)) {
                        device->flags |= ETH_8023_2_LSAP;
                } else {
                        device->flags |= ETH_8023_2_SNAP;
                }
                
                if (configuration[1].value &&
                    (configuration[1].value[0] == 'y')) {
                        device->flags |= ETH_DUMMY;
                }
                net_free_settings(configuration, data);
        } else {
                device->flags |= ETH_8023_2_SNAP;
        }
        
        /* Bind the device driver */
        device->sess = devman_device_connect(EXCHANGE_SERIALIZE, handle,
            IPC_FLAG_BLOCKING);
        if (device->sess == NULL) {
                fibril_rwlock_write_unlock(&eth_globals.devices_lock);
                free(device);
                return ENOENT;
        }
        
        nic_connect_to_nil(device->sess, SERVICE_ETHERNET, device_id);
        
        /* Get hardware address */
        rc = nic_get_address(device->sess, &device->addr);
        if (rc != EOK) {
                fibril_rwlock_write_unlock(&eth_globals.devices_lock);
                free(device);
                return rc;
        }
        
        /* Add to the cache */
        index = eth_devices_add(&eth_globals.devices, device->device_id,
            device);
        if (index < 0) {
                fibril_rwlock_write_unlock(&eth_globals.devices_lock);
                free(device);
                return index;
        }
        
        printf("%s: Device registered (id: %d, handle: %zu: mtu: %zu, "
            "mac: " PRIMAC ", flags: 0x%x)\n", NAME,
            device->device_id, device->handle, device->mtu,
            ARGSMAC(device->addr.address), device->flags);

        fibril_rwlock_write_unlock(&eth_globals.devices_lock);
        return EOK;
}

/** Processes the received packet and chooses the target registered module.
 *
 * @param[in] flags     The device flags.
 * @param[in] packet    The packet.
 * @return              The target registered module.
 * @return              NULL if the packet is not long enough.
 * @return              NULL if the packet is too long.
 * @return              NULL if the raw ethernet protocol is used.
 * @return              NULL if the dummy device FCS checksum is invalid.
 * @return              NULL if the packet address length is not big enough.
 */
static eth_proto_t *eth_process_packet(int flags, packet_t *packet)
{
        eth_header_snap_t *header;
        size_t length;
        eth_type_t type;
        size_t prefix;
        size_t suffix;
        eth_fcs_t *fcs;
        uint8_t *data;
        int rc;

        length = packet_get_data_length(packet);
        
        if (IS_DUMMY(flags))
                packet_trim(packet, sizeof(eth_preamble_t), 0);
        if (length < sizeof(eth_header_t) + ETH_MIN_CONTENT +
            (IS_DUMMY(flags) ? ETH_SUFFIX : 0))
                return NULL;
        
        data = packet_get_data(packet);
        header = (eth_header_snap_t *) data;
        type = ntohs(header->header.ethertype);
        
        if (type >= ETH_MIN_PROTO) {
                /* DIX Ethernet */
                prefix = sizeof(eth_header_t);
                suffix = 0;
                fcs = (eth_fcs_t *) data + length - sizeof(eth_fcs_t);
                length -= sizeof(eth_fcs_t);
        } else if (type <= ETH_MAX_CONTENT) {
                /* Translate "LSAP" values */
                if ((header->lsap.dsap == ETH_LSAP_GLSAP) &&
                    (header->lsap.ssap == ETH_LSAP_GLSAP)) {
                        /* Raw packet -- discard */
                        return NULL;
                } else if ((header->lsap.dsap == ETH_LSAP_SNAP) &&
                    (header->lsap.ssap == ETH_LSAP_SNAP)) {
                        /*
                         * IEEE 802.3 + 802.2 + LSAP + SNAP
                         * organization code not supported
                         */
                        type = ntohs(header->snap.ethertype);
                        prefix = sizeof(eth_header_t) + sizeof(eth_header_lsap_t) +
                            sizeof(eth_header_snap_t);
                } else {
                        /* IEEE 802.3 + 802.2 LSAP */
                        type = lsap_map(header->lsap.dsap);
                        prefix = sizeof(eth_header_t) + sizeof(eth_header_lsap_t);
                }

                suffix = (type < ETH_MIN_CONTENT) ? ETH_MIN_CONTENT - type : 0U;
                fcs = (eth_fcs_t *) data + prefix + type + suffix;
                suffix += length - prefix - type;
                length = prefix + type + suffix;
        } else {
                /* Invalid length/type, should not occur */
                return NULL;
        }
        
        if (IS_DUMMY(flags)) {
                if (~compute_crc32(~0U, data, length * 8) != ntohl(*fcs))
                        return NULL;
                suffix += sizeof(eth_fcs_t);
        }
        
        rc = packet_set_addr(packet, header->header.source_address,
            header->header.destination_address, ETH_ADDR);
        if (rc != EOK)
                return NULL;

        rc = packet_trim(packet, prefix, suffix);
        if (rc != EOK)
                return NULL;
        
        return eth_protos_find(&eth_globals.protos, type);
}

int nil_received_msg_local(nic_device_id_t device_id, packet_t *packet)
{
        eth_proto_t *proto;
        packet_t *next;
        eth_device_t *device;
        int flags;

        fibril_rwlock_read_lock(&eth_globals.devices_lock);
        device = eth_devices_find(&eth_globals.devices, device_id);
        if (!device) {
                fibril_rwlock_read_unlock(&eth_globals.devices_lock);
                return ENOENT;
        }

        flags = device->flags;
        fibril_rwlock_read_unlock(&eth_globals.devices_lock);
        fibril_rwlock_read_lock(&eth_globals.protos_lock);
        
        do {
                next = pq_detach(packet);
                proto = eth_process_packet(flags, packet);
                if (proto) {
                        il_received_msg(proto->sess, device_id, packet,
                            proto->service);
                } else {
                        /* Drop invalid/unknown */
                        pq_release_remote(eth_globals.net_sess,
                            packet_get_id(packet));
                }
                packet = next;
        } while (packet);

        fibril_rwlock_read_unlock(&eth_globals.protos_lock);
        return EOK;
}

/** Returns the device packet dimensions for sending.
 *
 * @param[in] device_id The device identifier.
 * @param[out] addr_len The minimum reserved address length.
 * @param[out] prefix   The minimum reserved prefix size.
 * @param[out] content  The maximum content size.
 * @param[out] suffix   The minimum reserved suffix size.
 * @return              EOK on success.
 * @return              EBADMEM if either one of the parameters is NULL.
 * @return              ENOENT if there is no such device.
 */
static int eth_packet_space_message(nic_device_id_t device_id, size_t *addr_len,
    size_t *prefix, size_t *content, size_t *suffix)
{
        eth_device_t *device;

        if (!addr_len || !prefix || !content || !suffix)
                return EBADMEM;
        
        fibril_rwlock_read_lock(&eth_globals.devices_lock);
        device = eth_devices_find(&eth_globals.devices, device_id);
        if (!device) {
                fibril_rwlock_read_unlock(&eth_globals.devices_lock);
                return ENOENT;
        }

        *content = device->mtu;
        fibril_rwlock_read_unlock(&eth_globals.devices_lock);
        
        *addr_len = ETH_ADDR;
        *prefix = ETH_PREFIX;
        *suffix = ETH_MIN_CONTENT + ETH_SUFFIX;

        return EOK;
}

/** Send the device hardware address.
 *
 * @param[in] device_id The device identifier.
 * @param[in] type      Type of the desired address.
 * @return              EOK on success.
 * @return              EBADMEM if the address parameter is NULL.
 * @return              ENOENT if there no such device.
 */
static int eth_addr_message(nic_device_id_t device_id, eth_addr_type_t type)
{
        eth_device_t *device = NULL;
        uint8_t *address;
        size_t max_len;
        ipc_callid_t callid;
        
        if (type == ETH_BROADCAST_ADDR)
                address = eth_globals.broadcast_addr;
        else {
                fibril_rwlock_read_lock(&eth_globals.devices_lock);
                device = eth_devices_find(&eth_globals.devices, device_id);
                if (!device) {
                        fibril_rwlock_read_unlock(&eth_globals.devices_lock);
                        return ENOENT;
                }
                
                address = (uint8_t *) &device->addr.address;
        }
        
        int rc = EOK;
        if (!async_data_read_receive(&callid, &max_len)) {
                rc = EREFUSED;
                goto end;
        }
        
        if (max_len < ETH_ADDR) {
                async_data_read_finalize(callid, NULL, 0);
                rc = ELIMIT;
                goto end;
        }
        
        rc = async_data_read_finalize(callid, address, ETH_ADDR);
        if (rc != EOK)
                goto end;
        
end:
        
        if (type == ETH_LOCAL_ADDR)
                fibril_rwlock_read_unlock(&eth_globals.devices_lock);
        
        return rc;
}

/** Register receiving module service.
 *
 * Pass received packets for this service.
 *
 * @param[in] service Module service.
 * @param[in] sess    Service session.
 *
 * @return EOK on success.
 * @return ENOENT if the service is not known.
 * @return ENOMEM if there is not enough memory left.
 *
 */
static int eth_register_message(services_t service, async_sess_t *sess)
{
        eth_proto_t *proto;
        int protocol;
        int index;

        protocol = protocol_map(SERVICE_ETHERNET, service);
        if (!protocol)
                return ENOENT;

        fibril_rwlock_write_lock(&eth_globals.protos_lock);
        proto = eth_protos_find(&eth_globals.protos, protocol);
        if (proto) {
                proto->sess = sess;
                fibril_rwlock_write_unlock(&eth_globals.protos_lock);
                return EOK;
        } else {
                proto = (eth_proto_t *) malloc(sizeof(eth_proto_t));
                if (!proto) {
                        fibril_rwlock_write_unlock(&eth_globals.protos_lock);
                        return ENOMEM;
                }

                proto->service = service;
                proto->protocol = protocol;
                proto->sess = sess;

                index = eth_protos_add(&eth_globals.protos, protocol, proto);
                if (index < 0) {
                        fibril_rwlock_write_unlock(&eth_globals.protos_lock);
                        free(proto);
                        return index;
                }
        }
        
        printf("%s: Protocol registered (protocol: %d, service: %#x)\n",
            NAME, proto->protocol, proto->service);
        
        fibril_rwlock_write_unlock(&eth_globals.protos_lock);
        return EOK;
}

/** Prepares the packet for sending.
 *
 * @param[in] flags     The device flags.
 * @param[in] packet    The packet.
 * @param[in] src_addr  The source hardware address.
 * @param[in] ethertype The ethernet protocol type.
 * @param[in] mtu       The device maximum transmission unit.
 * @return              EOK on success.
 * @return              EINVAL if the packet addresses length is not long
 *                      enough.
 * @return              EINVAL if the packet is bigger than the device MTU.
 * @return              ENOMEM if there is not enough memory in the packet.
 */
static int
eth_prepare_packet(int flags, packet_t *packet, uint8_t *src_addr, int ethertype,
    size_t mtu)
{
        eth_header_snap_t *header;
        eth_header_lsap_t *header_lsap;
        eth_header_t *header_dix;
        eth_fcs_t *fcs;
        uint8_t *src;
        uint8_t *dest;
        size_t length;
        int i;
        void *padding;
        eth_preamble_t *preamble;

        i = packet_get_addr(packet, &src, &dest);
        if (i < 0)
                return i;
        
        if (i != ETH_ADDR)
                return EINVAL;
        
        for (i = 0; i < ETH_ADDR; i++) {
                if (src[i]) {
                        src_addr = src;
                        break;
                }
        }

        length = packet_get_data_length(packet);
        if (length > mtu)
                return EINVAL;
        
        if (length < ETH_MIN_TAGGED_CONTENT(flags)) {
                padding = packet_suffix(packet,
                    ETH_MIN_TAGGED_CONTENT(flags) - length);
                if (!padding)
                        return ENOMEM;

                bzero(padding, ETH_MIN_TAGGED_CONTENT(flags) - length);
        }
        
        if (IS_DIX(flags)) {
                header_dix = PACKET_PREFIX(packet, eth_header_t);
                if (!header_dix)
                        return ENOMEM;
                
                header_dix->ethertype = (uint16_t) ethertype;
                memcpy(header_dix->source_address, src_addr, ETH_ADDR);
                memcpy(header_dix->destination_address, dest, ETH_ADDR);
                src = &header_dix->destination_address[0];
        } else if (IS_8023_2_LSAP(flags)) {
                header_lsap = PACKET_PREFIX(packet, eth_header_lsap_t);
                if (!header_lsap)
                        return ENOMEM;
                
                header_lsap->header.ethertype = htons(length +
                    sizeof(eth_header_lsap_t));
                header_lsap->lsap.dsap = lsap_unmap(ntohs(ethertype));
                header_lsap->lsap.ssap = header_lsap->lsap.dsap;
                header_lsap->lsap.ctrl = IEEE_8023_2_UI;
                memcpy(header_lsap->header.source_address, src_addr, ETH_ADDR);
                memcpy(header_lsap->header.destination_address, dest, ETH_ADDR);
                src = &header_lsap->header.destination_address[0];
        } else if (IS_8023_2_SNAP(flags)) {
                header = PACKET_PREFIX(packet, eth_header_snap_t);
                if (!header)
                        return ENOMEM;
                
                header->header.ethertype = htons(length +
                    sizeof(eth_header_lsap_t) + sizeof(eth_header_snap_t));
                header->lsap.dsap = (uint16_t) ETH_LSAP_SNAP;
                header->lsap.ssap = header->lsap.dsap;
                header->lsap.ctrl = IEEE_8023_2_UI;
                
                for (i = 0; i < 3; i++)
                        header->snap.protocol[i] = 0;
                
                header->snap.ethertype = (uint16_t) ethertype;
                memcpy(header->header.source_address, src_addr, ETH_ADDR);
                memcpy(header->header.destination_address, dest, ETH_ADDR);
                src = &header->header.destination_address[0];
        }
        
        if (IS_DUMMY(flags)) {
                preamble = PACKET_PREFIX(packet, eth_preamble_t);
                if (!preamble)
                        return ENOMEM;
                
                for (i = 0; i < 7; i++)
                        preamble->preamble[i] = ETH_PREAMBLE;
                
                preamble->sfd = ETH_SFD;
                
                fcs = PACKET_SUFFIX(packet, eth_fcs_t);
                if (!fcs)
                        return ENOMEM;

                *fcs = htonl(~compute_crc32(~0U, src, length * 8));
        }
        
        return EOK;
}

/** Sends the packet queue.
 *
 * Sends only packet successfully processed by the eth_prepare_packet()
 * function.
 *
 * @param[in] device_id The device identifier.
 * @param[in] packet    The packet queue.
 * @param[in] sender    The sending module service.
 * @return              EOK on success.
 * @return              ENOENT if there no such device.
 * @return              EINVAL if the service parameter is not known.
 */
static int eth_send_message(nic_device_id_t device_id, packet_t *packet,
    services_t sender)
{
        eth_device_t *device;
        packet_t *next;
        packet_t *tmp;
        int ethertype;
        int rc;

        ethertype = htons(protocol_map(SERVICE_ETHERNET, sender));
        if (!ethertype) {
                pq_release_remote(eth_globals.net_sess, packet_get_id(packet));
                return EINVAL;
        }
        
        fibril_rwlock_read_lock(&eth_globals.devices_lock);
        device = eth_devices_find(&eth_globals.devices, device_id);
        if (!device) {
                fibril_rwlock_read_unlock(&eth_globals.devices_lock);
                return ENOENT;
        }
        
        /* Process packet queue */
        next = packet;
        do {
                rc = eth_prepare_packet(device->flags, next,
                    (uint8_t *) &device->addr.address, ethertype, device->mtu);
                if (rc != EOK) {
                        /* Release invalid packet */
                        tmp = pq_detach(next);
                        if (next == packet)
                                packet = tmp;
                        pq_release_remote(eth_globals.net_sess,
                            packet_get_id(next));
                        next = tmp;
                } else {
                        next = pq_next(next);
                }
        } while (next);
        
        /* Send packet queue */
        if (packet)
                nic_send_message(device->sess, packet_get_id(packet));
        
        fibril_rwlock_read_unlock(&eth_globals.devices_lock);
        return EOK;
}

static int eth_addr_changed(nic_device_id_t device_id)
{
        nic_address_t address;
        size_t length;
        ipc_callid_t data_callid;
        if (!async_data_write_receive(&data_callid, &length)) {
                async_answer_0(data_callid, EINVAL);
                return EINVAL;
        }
        if (length > sizeof (nic_address_t)) {
                async_answer_0(data_callid, ELIMIT);
                return ELIMIT;
        }
        if (async_data_write_finalize(data_callid, &address, length) != EOK) {
                return EINVAL;
        }

        fibril_rwlock_write_lock(&eth_globals.devices_lock);
        /* An existing device? */
        eth_device_t *device = eth_devices_find(&eth_globals.devices, device_id);
        if (device) {
                printf("Device %d changing address from " PRIMAC " to " PRIMAC "\n",
                        device_id, ARGSMAC(device->addr.address), ARGSMAC(address.address));
                memcpy(&device->addr, &address, sizeof (nic_address_t));
                fibril_rwlock_write_unlock(&eth_globals.devices_lock);

                /* Notify all upper layer modules */
                fibril_rwlock_read_lock(&eth_globals.protos_lock);
                int index;
                for (index = 0; index < eth_protos_count(&eth_globals.protos); index++) {
                        eth_proto_t *proto = eth_protos_get_index(&eth_globals.protos, index);
                        if (proto->sess != NULL) {
                                il_addr_changed_msg(proto->sess, device->device_id,
                                                ETH_ADDR, address.address);
                        }
                }

                fibril_rwlock_read_unlock(&eth_globals.protos_lock);
                return EOK;
        } else {
                return ENOENT;
        }
}

int nil_module_message(ipc_callid_t callid, ipc_call_t *call,
    ipc_call_t *answer, size_t *answer_count)
{
        packet_t *packet;
        size_t addrlen;
        size_t prefix;
        size_t suffix;
        size_t content;
        int rc;
        
        *answer_count = 0;
        
        if (!IPC_GET_IMETHOD(*call))
                return EOK;
        
        async_sess_t *callback =
            async_callback_receive_start(EXCHANGE_SERIALIZE, call);
        if (callback)
                return eth_register_message(NIL_GET_PROTO(*call), callback);
        
        switch (IPC_GET_IMETHOD(*call)) {
        case NET_NIL_DEVICE:
                return eth_device_message(IPC_GET_DEVICE(*call),
                    IPC_GET_DEVICE_HANDLE(*call), IPC_GET_MTU(*call));
        case NET_NIL_SEND:
                rc = packet_translate_remote(eth_globals.net_sess, &packet,
                    IPC_GET_PACKET(*call));
                if (rc != EOK)
                        return rc;
                
                return eth_send_message(IPC_GET_DEVICE(*call), packet,
                    IPC_GET_SERVICE(*call));
        case NET_NIL_PACKET_SPACE:
                rc = eth_packet_space_message(IPC_GET_DEVICE(*call), &addrlen,
                    &prefix, &content, &suffix);
                if (rc != EOK)
                        return rc;
                
                IPC_SET_ADDR(*answer, addrlen);
                IPC_SET_PREFIX(*answer, prefix);
                IPC_SET_CONTENT(*answer, content);
                IPC_SET_SUFFIX(*answer, suffix);
                *answer_count = 4;
                
                return EOK;
        case NET_NIL_ADDR:
                rc = eth_addr_message(IPC_GET_DEVICE(*call), ETH_LOCAL_ADDR);
                if (rc != EOK)
                        return rc;
                
                IPC_SET_ADDR(*answer, ETH_ADDR);
                *answer_count = 1;
                
                return EOK;
        case NET_NIL_BROADCAST_ADDR:
                rc = eth_addr_message(IPC_GET_DEVICE(*call), ETH_BROADCAST_ADDR);
                if (rc != EOK)
                        return rc;
                
                IPC_SET_ADDR(*answer, ETH_ADDR);
                *answer_count = 1;
                
                return EOK;
        case NET_NIL_DEVICE_STATE:
                nil_device_state_msg_local(IPC_GET_DEVICE(*call), IPC_GET_STATE(*call));
                async_answer_0(callid, EOK);
                return EOK;
        case NET_NIL_RECEIVED:
                rc = packet_translate_remote(eth_globals.net_sess, &packet,
                    IPC_GET_ARG2(*call));
                if (rc == EOK)
                        rc = nil_received_msg_local(IPC_GET_ARG1(*call), packet);
                
                async_answer_0(callid, (sysarg_t) rc);
                return rc;
        case NET_NIL_ADDR_CHANGED:
                rc = eth_addr_changed(IPC_GET_DEVICE(*call));
                async_answer_0(callid, (sysarg_t) rc);
                return rc;
        }
        
        return ENOTSUP;
}

int main(int argc, char *argv[])
{
        /* Start the module */
        return nil_module_start(SERVICE_ETHERNET);
}

/** @}
 */