source: mainline/uspace/srv/net/slip/slip.c@ a53ed3a

/*
 * Copyright (c) 2013 Jakub Jermar
 * 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 slip
 * @{
 */
/**
 * @file
 * @brief IP over serial line IP link provider.
 */

#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <loc.h>
#include <inet/addr.h>
#include <inet/iplink_srv.h>
#include <io/chardev.h>
#include <io/log.h>
#include <errno.h>
#include <str_error.h>
#include <task.h>

#define NAME            "slip"
#define CAT_IPLINK      "iplink"

#define SLIP_MTU        1006    /* as per RFC 1055 */

#define SLIP_END        0300
#define SLIP_ESC        0333
#define SLIP_ESC_END    0334
#define SLIP_ESC_ESC    0335

static errno_t slip_open(iplink_srv_t *);
static errno_t slip_close(iplink_srv_t *);
static errno_t slip_send(iplink_srv_t *, iplink_sdu_t *);
static errno_t slip_send6(iplink_srv_t *, iplink_sdu6_t *);
static errno_t slip_get_mtu(iplink_srv_t *, size_t *);
static errno_t slip_get_mac48(iplink_srv_t *, addr48_t *);
static errno_t slip_addr_add(iplink_srv_t *, inet_addr_t *);
static errno_t slip_addr_remove(iplink_srv_t *, inet_addr_t *);

static iplink_srv_t slip_iplink;

static iplink_ops_t slip_iplink_ops = {
        .open = slip_open,
        .close = slip_close,
        .send = slip_send,
        .send6 = slip_send6,
        .get_mtu = slip_get_mtu,
        .get_mac48 = slip_get_mac48,
        .addr_add = slip_addr_add,
        .addr_remove = slip_addr_remove
};

static uint8_t slip_send_buf[SLIP_MTU + 2];
static size_t slip_send_pending;

static uint8_t slip_recv_buf[SLIP_MTU + 2];
static size_t slip_recv_pending;
static size_t slip_recv_read;

errno_t slip_open(iplink_srv_t *srv)
{
        log_msg(LOG_DEFAULT, LVL_DEBUG, "slip_open()");
        return EOK;
}

errno_t slip_close(iplink_srv_t *srv)
{
        log_msg(LOG_DEFAULT, LVL_DEBUG, "slip_close()");
        return EOK;
}

static void write_flush(chardev_t *chardev)
{
        size_t written = 0;

        while (slip_send_pending > 0) {
                errno_t rc;
                size_t nwr;

                rc = chardev_write(chardev, &slip_send_buf[written],
                    slip_send_pending, &nwr);
                if (rc != EOK) {
                        log_msg(LOG_DEFAULT, LVL_ERROR,
                            "chardev_write() -> %s", str_error_name(rc));
                        slip_send_pending = 0;
                        break;
                }
                written += nwr;
                slip_send_pending -= nwr;
        }
}

static void write_buffered(chardev_t *chardev, uint8_t ch)
{
        if (slip_send_pending == sizeof(slip_send_buf))
                write_flush(chardev);
        slip_send_buf[slip_send_pending++] = ch;
}

errno_t slip_send(iplink_srv_t *srv, iplink_sdu_t *sdu)
{
        log_msg(LOG_DEFAULT, LVL_DEBUG, "slip_send()");
        
        chardev_t *chardev = (chardev_t *) srv->arg;
        uint8_t *data = sdu->data;
        
        /*
         * Strictly speaking, this is not prescribed by the RFC, but the RFC
         * suggests to start with sending a SLIP_END byte as a synchronization
         * measure for dealing with previous possible noise on the line.
         */
        write_buffered(chardev, SLIP_END);
        
        for (size_t i = 0; i < sdu->size; i++) {
                switch (data[i]) {
                case SLIP_END:
                        write_buffered(chardev, SLIP_ESC);
                        write_buffered(chardev, SLIP_ESC_END);
                        break;
                case SLIP_ESC:
                        write_buffered(chardev, SLIP_ESC);
                        write_buffered(chardev, SLIP_ESC_ESC);
                        break;
                default:
                        write_buffered(chardev, data[i]);
                        break;
                }
        }
        
        write_buffered(chardev, SLIP_END);
        write_flush(chardev);
        
        return EOK;
}

errno_t slip_send6(iplink_srv_t *srv, iplink_sdu6_t *sdu)
{
        log_msg(LOG_DEFAULT, LVL_DEBUG, "slip_send6()");
        
        return ENOTSUP;
}

errno_t slip_get_mtu(iplink_srv_t *srv, size_t *mtu)
{
        log_msg(LOG_DEFAULT, LVL_DEBUG, "slip_get_mtu()");
        *mtu = SLIP_MTU;
        return EOK;
}

errno_t slip_get_mac48(iplink_srv_t *src, addr48_t *mac)
{
        log_msg(LOG_DEFAULT, LVL_DEBUG, "slip_get_mac48()");
        return ENOTSUP;
}

errno_t slip_addr_add(iplink_srv_t *srv, inet_addr_t *addr)
{
        log_msg(LOG_DEFAULT, LVL_DEBUG, "slip_addr_add()");
        return EOK;
}

errno_t slip_addr_remove(iplink_srv_t *srv, inet_addr_t *addr)
{
        log_msg(LOG_DEFAULT, LVL_DEBUG, "slip_addr_remove()");
        return EOK;
}

static void usage(void)
{
        printf("Usage: " NAME " <service-name> <link-name>\n");
}

static void slip_client_conn(ipc_callid_t iid, ipc_call_t *icall, void *arg)
{
        log_msg(LOG_DEFAULT, LVL_DEBUG, "slip_client_conn()");
        iplink_conn(iid, icall, &slip_iplink);
}

static uint8_t read_buffered(chardev_t *chardev)
{
        while (slip_recv_pending == 0) {
                errno_t rc;
                size_t nread;

                rc = chardev_read(chardev, slip_recv_buf,
                    sizeof(slip_recv_buf), &nread);
                if (rc != EOK) {
                        log_msg(LOG_DEFAULT, LVL_ERROR,
                            "char_dev_read() -> %s", str_error_name(rc));
                }

                if (nread == 0)
                        return SLIP_END;

                slip_recv_pending = nread;
                slip_recv_read = 0;
        }
        slip_recv_pending--;
        return slip_recv_buf[slip_recv_read++];
}

static errno_t slip_recv_fibril(void *arg)
{
        chardev_t *chardev = (chardev_t *) arg;
        static uint8_t recv_final[SLIP_MTU];
        iplink_recv_sdu_t sdu;
        uint8_t ch;
        errno_t rc;

        sdu.data = recv_final;

        while (true) {
                for (sdu.size = 0; sdu.size < sizeof(recv_final); /**/) {
                        ch = read_buffered(chardev);
                        switch (ch) {
                        case SLIP_END:
                                if (sdu.size == 0) {
                                        /*
                                         * Discard the empty SLIP datagram.
                                         */
                                        break;
                                }
                                goto pass;

                        case SLIP_ESC:
                                ch = read_buffered(chardev);
                                if (ch == SLIP_ESC_END) {
                                        recv_final[sdu.size++] = SLIP_END;
                                        break;
                                } else if (ch == SLIP_ESC_ESC) {
                                        recv_final[sdu.size++] = SLIP_ESC;
                                        break;
                                }

                                /*
                                 * The RFC suggests to simply insert the wrongly
                                 * escaped character into the packet so we fall
                                 * through.
                                 */
                                /* Fallthrough */

                        default:
                                recv_final[sdu.size++] = ch;
                                break;
                        }
                        
                }

                /*
                 * We have reached the limit of our MTU. Regardless of whether
                 * the datagram is properly ended with SLIP_END, pass it along.
                 * If the next character is really SLIP_END, nothing
                 * catastrophic happens. The algorithm will just see an
                 * artificially empty SLIP datagram and life will go on.
                 */

pass:
                rc = iplink_ev_recv(&slip_iplink, &sdu, ip_v4);
                if (rc != EOK) {
                        log_msg(LOG_DEFAULT, LVL_ERROR,
                            "iplink_ev_recv() -> %s", str_error_name(rc));
                }
        }

        return 0;
}

static errno_t slip_init(const char *svcstr, const char *linkstr)
{
        service_id_t svcid;
        service_id_t linksid;
        category_id_t iplinkcid;
        async_sess_t *sess_in = NULL;
        async_sess_t *sess_out = NULL;
        chardev_t *chardev_in = NULL;
        chardev_t *chardev_out = NULL;
        fid_t fid;
        errno_t rc;

        iplink_srv_init(&slip_iplink);
        slip_iplink.ops = &slip_iplink_ops;

        async_set_fallback_port_handler(slip_client_conn, NULL);

        rc = loc_server_register(NAME);
        if (rc != EOK) {
                log_msg(LOG_DEFAULT, LVL_ERROR,
                    "Failed registering server.");
                return rc;
        }

        rc = loc_service_get_id(svcstr, &svcid, 0);
        if (rc != EOK) {
                log_msg(LOG_DEFAULT, LVL_ERROR,
                    "Failed getting ID for service %s", svcstr);
                return rc;
        }

        rc = loc_category_get_id(CAT_IPLINK, &iplinkcid, 0);
        if (rc != EOK) {
                log_msg(LOG_DEFAULT, LVL_ERROR,
                    "Failed to get category ID for %s",
                    CAT_IPLINK);
                return rc;
        }

        /*
         * Create two sessions to allow to both read and write from the
         * char_dev at the same time.
         */
        sess_out = loc_service_connect(svcid, INTERFACE_DDF, 0);
        if (!sess_out) {
                log_msg(LOG_DEFAULT, LVL_ERROR,
                    "Failed to connect to service %s (ID=%d)",
                    svcstr, (int) svcid);
                return ENOENT;
        }

        rc = chardev_open(sess_out, &chardev_out);
        if (rc != EOK) {
                log_msg(LOG_DEFAULT, LVL_ERROR,
                    "Failed opening character device.");
                return ENOENT;
        }

        slip_iplink.arg = chardev_out;

        sess_in = loc_service_connect(svcid, INTERFACE_DDF, 0);
        if (!sess_in) {
                log_msg(LOG_DEFAULT, LVL_ERROR,
                    "Failed to connect to service %s (ID=%d)",
                    svcstr, (int) svcid);
                rc = ENOENT;
                goto fail;
        }

        rc = chardev_open(sess_in, &chardev_in);
        if (rc != EOK) {
                log_msg(LOG_DEFAULT, LVL_ERROR,
                    "Failed opening character device.");
                return ENOENT;
        }

        rc = loc_service_register(linkstr, &linksid);
        if (rc != EOK) {
                log_msg(LOG_DEFAULT, LVL_ERROR,
                   "Failed to register service %s",
                   linkstr);
                goto fail;
        }

        rc = loc_service_add_to_cat(linksid, iplinkcid);
        if (rc != EOK) {
                log_msg(LOG_DEFAULT, LVL_ERROR,
                    "Failed to add service %d (%s) to category %d (%s).",
                    (int) linksid, linkstr, (int) iplinkcid, CAT_IPLINK);
                goto fail;
        }

        fid = fibril_create(slip_recv_fibril, chardev_in);
        if (!fid) {
                log_msg(LOG_DEFAULT, LVL_ERROR,
                    "Failed to create receive fibril.");
                rc = ENOENT;
                goto fail;
        }
        fibril_add_ready(fid);

        return EOK;

fail:
        chardev_close(chardev_out);
        if (sess_out)
                async_hangup(sess_out);
        chardev_close(chardev_in);
        if (sess_in)
                async_hangup(sess_in);

        /*
         * We assume that our registration at the location service will be
         * cleaned up automatically as the service (i.e. this task) terminates.
         */

        return rc;
}

int main(int argc, char *argv[])
{
        errno_t rc;

        printf(NAME ": IP over serial line service\n");

        if (argc != 3) {
                usage();
                return EINVAL;
        }

        rc = log_init(NAME);
        if (rc != EOK) {
                printf(NAME ": failed to initialize log\n");
                return rc;
        }

        rc = slip_init(argv[1], argv[2]);
        if (rc != EOK)
                return 1;

        printf(NAME ": Accepting connections.\n");
        task_retval(0);
        async_manager();

        /* not reached */
        return 0;
}

/** @}
 */