source: mainline/uspace/srv/hid/remcons/user.c

/*
 * Copyright (c) 2024 Jiri Svoboda
 * Copyright (c) 2012 Vojtech Horky
 * 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 remcons
 * @{
 */
/** @file
 */
#include <async.h>
#include <stdio.h>
#include <stdlib.h>
#include <adt/prodcons.h>
#include <errno.h>
#include <macros.h>
#include <mem.h>
#include <str_error.h>
#include <loc.h>
#include <io/keycode.h>
#include <align.h>
#include <as.h>
#include <fibril_synch.h>
#include <task.h>
#include <inet/tcp.h>
#include <io/console.h>
#include <inttypes.h>
#include <assert.h>
#include "remcons.h"
#include "user.h"
#include "telnet.h"

static FIBRIL_MUTEX_INITIALIZE(users_guard);
static LIST_INITIALIZE(users);

static errno_t telnet_user_send_raw_locked(telnet_user_t *, const void *,
    size_t);
static errno_t telnet_user_flush_locked(telnet_user_t *);

/** Create new telnet user.
 *
 * @param conn Incoming connection.
 * @param cb Callback functions
 * @param arg Argument to callback functions
 * @return New telnet user or NULL when out of memory.
 */
telnet_user_t *telnet_user_create(tcp_conn_t *conn, telnet_cb_t *cb, void *arg)
{
        static int telnet_user_id_counter = 0;

        telnet_user_t *user = malloc(sizeof(telnet_user_t));
        if (user == NULL) {
                return NULL;
        }

        user->cb = cb;
        user->arg = arg;
        user->id = ++telnet_user_id_counter;

        int rc = asprintf(&user->service_name, "%s/telnet%u.%d", NAMESPACE,
            (unsigned)task_get_id(), user->id);
        if (rc < 0) {
                free(user);
                return NULL;
        }

        user->conn = conn;
        user->service_id = (service_id_t) -1;
        link_initialize(&user->link);
        user->socket_buffer_len = 0;
        user->socket_buffer_pos = 0;
        user->send_buf_used = 0;

        fibril_condvar_initialize(&user->refcount_cv);
        fibril_mutex_initialize(&user->send_lock);
        fibril_mutex_initialize(&user->recv_lock);
        user->task_finished = false;
        user->socket_closed = false;
        user->locsrv_connection_count = 0;

        user->cursor_x = 0;
        user->cursor_y = 0;

        return user;
}

void telnet_user_add(telnet_user_t *user)
{
        fibril_mutex_lock(&users_guard);
        list_append(&user->link, &users);
        fibril_mutex_unlock(&users_guard);
}

/** Destroy telnet user structure.
 *
 * @param user User to be destroyed.
 */
void telnet_user_destroy(telnet_user_t *user)
{
        assert(user);

        fibril_mutex_lock(&users_guard);
        list_remove(&user->link);
        fibril_mutex_unlock(&users_guard);

        free(user);
}

/** Find user by service id and increments reference counter.
 *
 * @param id Location service id of the telnet user's terminal.
 */
telnet_user_t *telnet_user_get_for_client_connection(service_id_t id)
{
        telnet_user_t *user = NULL;

        fibril_mutex_lock(&users_guard);
        list_foreach(users, link, telnet_user_t, tmp) {
                if (tmp->service_id == id) {
                        user = tmp;
                        break;
                }
        }
        if (user == NULL) {
                fibril_mutex_unlock(&users_guard);
                return NULL;
        }

        telnet_user_t *tmp = user;
        fibril_mutex_lock(&tmp->recv_lock);
        user->locsrv_connection_count++;

        /*
         * Refuse to return user whose task already finished or when
         * the socket is already closed().
         */
        if (user->task_finished || user->socket_closed) {
                user = NULL;
                user->locsrv_connection_count--;
        }

        fibril_mutex_unlock(&tmp->recv_lock);

        fibril_mutex_unlock(&users_guard);

        return user;
}

/** Notify that client disconnected from the remote terminal.
 *
 * @param user To which user the client was connected.
 */
void telnet_user_notify_client_disconnected(telnet_user_t *user)
{
        fibril_mutex_lock(&user->recv_lock);
        assert(user->locsrv_connection_count > 0);
        user->locsrv_connection_count--;
        fibril_condvar_signal(&user->refcount_cv);
        fibril_mutex_unlock(&user->recv_lock);
}

/** Tell whether the launched task already exited and socket is already closed.
 *
 * @param user Telnet user in question.
 */
bool telnet_user_is_zombie(telnet_user_t *user)
{
        fibril_mutex_lock(&user->recv_lock);
        bool zombie = user->socket_closed || user->task_finished;
        fibril_mutex_unlock(&user->recv_lock);

        return zombie;
}

static errno_t telnet_user_fill_recv_buf(telnet_user_t *user)
{
        errno_t rc;
        size_t recv_length;

        rc = tcp_conn_recv_wait(user->conn, user->socket_buffer,
            BUFFER_SIZE, &recv_length);
        if (rc != EOK)
                return rc;

        if (recv_length == 0) {
                user->socket_closed = true;
                user->srvs.aborted = true;
                return ENOENT;
        }

        user->socket_buffer_len = recv_length;
        user->socket_buffer_pos = 0;

        return EOK;
}

/** Receive next byte from a socket (use buffering).
 *
 * @param user Telnet user
 * @param byte Place to store the received byte
 * @return EOK on success or an error code
 */
static errno_t telnet_user_recv_next_byte_locked(telnet_user_t *user,
    uint8_t *byte)
{
        errno_t rc;

        /* No more buffered data? */
        if (user->socket_buffer_len <= user->socket_buffer_pos) {
                rc = telnet_user_fill_recv_buf(user);
                if (rc != EOK)
                        return rc;
        }

        *byte = (uint8_t)user->socket_buffer[user->socket_buffer_pos++];
        return EOK;
}

/** Determine if a received byte is available without waiting.
 *
 * @param user Telnet user
 * @return @c true iff a byte is currently available
 */
static bool telnet_user_byte_avail(telnet_user_t *user)
{
        return user->socket_buffer_len > user->socket_buffer_pos;
}

static errno_t telnet_user_send_opt(telnet_user_t *user, telnet_cmd_t cmd,
    telnet_cmd_t opt)
{
        uint8_t cmdb[3];

        cmdb[0] = TELNET_IAC;
        cmdb[1] = cmd;
        cmdb[2] = opt;

        return telnet_user_send_raw_locked(user, (char *)cmdb, sizeof(cmdb));
}

/** Process telnet WILL NAWS command.
 *
 * @param user Telnet user structure.
 * @param cmd Telnet command.
 */
static void process_telnet_will_naws(telnet_user_t *user)
{
        telnet_user_log(user, "WILL NAWS");
        /* Send DO NAWS */
        (void) telnet_user_send_opt(user, TELNET_DO, TELNET_NAWS);
        (void) telnet_user_flush_locked(user);
}

/** Process telnet SB NAWS command.
 *
 * @param user Telnet user structure.
 * @param cmd Telnet command.
 */
static void process_telnet_sb_naws(telnet_user_t *user)
{
        uint8_t chi, clo;
        uint8_t rhi, rlo;
        uint16_t cols;
        uint16_t rows;
        uint8_t iac;
        uint8_t se;
        errno_t rc;

        telnet_user_log(user, "SB NAWS...");

        rc = telnet_user_recv_next_byte_locked(user, &chi);
        if (rc != EOK)
                return;
        rc = telnet_user_recv_next_byte_locked(user, &clo);
        if (rc != EOK)
                return;

        rc = telnet_user_recv_next_byte_locked(user, &rhi);
        if (rc != EOK)
                return;
        rc = telnet_user_recv_next_byte_locked(user, &rlo);
        if (rc != EOK)
                return;

        rc = telnet_user_recv_next_byte_locked(user, &iac);
        if (rc != EOK)
                return;
        rc = telnet_user_recv_next_byte_locked(user, &se);
        if (rc != EOK)
                return;

        cols = (chi << 8) | clo;
        rows = (rhi << 8) | rlo;

        telnet_user_log(user, "cols=%u rows=%u\n", cols, rows);

        if (cols < 1 || rows < 1) {
                telnet_user_log(user, "Ignoring invalid window size update.");
                return;
        }

        user->cb->ws_update(user->arg, cols, rows);
}

/** Process telnet WILL command.
 *
 * @param user Telnet user structure.
 * @param opt Option code.
 */
static void process_telnet_will(telnet_user_t *user, telnet_cmd_t opt)
{
        telnet_user_log(user, "WILL");
        switch (opt) {
        case TELNET_NAWS:
                process_telnet_will_naws(user);
                return;
        }

        telnet_user_log(user, "Ignoring telnet command %u %u %u.",
            TELNET_IAC, TELNET_WILL, opt);
}

/** Process telnet SB command.
 *
 * @param user Telnet user structure.
 * @param opt Option code.
 */
static void process_telnet_sb(telnet_user_t *user, telnet_cmd_t opt)
{
        telnet_user_log(user, "SB");
        switch (opt) {
        case TELNET_NAWS:
                process_telnet_sb_naws(user);
                return;
        }

        telnet_user_log(user, "Ignoring telnet command %u %u %u.",
            TELNET_IAC, TELNET_SB, opt);
}

/** Process telnet command.
 *
 * @param user Telnet user structure.
 * @param option_code Command option code.
 * @param cmd Telnet command.
 */
static void process_telnet_command(telnet_user_t *user,
    telnet_cmd_t option_code, telnet_cmd_t cmd)
{
        switch (option_code) {
        case TELNET_SB:
                process_telnet_sb(user, cmd);
                return;
        case TELNET_WILL:
                process_telnet_will(user, cmd);
                return;
        }

        if (option_code != 0) {
                telnet_user_log(user, "Ignoring telnet command %u %u %u.",
                    TELNET_IAC, option_code, cmd);
        } else {
                telnet_user_log(user, "Ignoring telnet command %u %u.",
                    TELNET_IAC, cmd);
        }
}

/** Receive data from telnet connection.
 *
 * @param user Telnet user.
 * @param buf Destination buffer
 * @param size Buffer size
 * @param nread Place to store number of bytes read (>0 on success)
 * @return EOK on success or an error code
 */
errno_t telnet_user_recv(telnet_user_t *user, void *buf, size_t size,
    size_t *nread)
{
        uint8_t *bp = (uint8_t *)buf;
        fibril_mutex_lock(&user->recv_lock);

        assert(size > 0);
        *nread = 0;

        do {
                uint8_t next_byte = 0;
                bool inside_telnet_command = false;

                telnet_cmd_t telnet_option_code = 0;

                /* Skip zeros, bail-out on error. */
                do {
                        errno_t rc = telnet_user_recv_next_byte_locked(user,
                            &next_byte);
                        if (rc != EOK) {
                                fibril_mutex_unlock(&user->recv_lock);
                                return rc;
                        }
                        uint8_t byte = next_byte;

                        /* Skip telnet commands. */
                        if (inside_telnet_command) {
                                inside_telnet_command = false;
                                next_byte = 0;
                                if (TELNET_IS_OPTION_CODE(byte) ||
                                    byte == TELNET_SB) {
                                        telnet_option_code = byte;
                                        inside_telnet_command = true;
                                } else {
                                        process_telnet_command(user,
                                            telnet_option_code, byte);
                                }
                        }
                        if (byte == TELNET_IAC) {
                                inside_telnet_command = true;
                                next_byte = 0;
                        }
                } while (next_byte == 0 && telnet_user_byte_avail(user));

                /* CR-LF conversions. */
                if (next_byte == 13) {
                        next_byte = 10;
                }

                if (next_byte != 0) {
                        *bp++ = next_byte;
                        ++*nread;
                        --size;
                }
        } while (size > 0 && (telnet_user_byte_avail(user) || *nread == 0));

        fibril_mutex_unlock(&user->recv_lock);
        return EOK;
}

static errno_t telnet_user_send_raw_locked(telnet_user_t *user,
    const void *data, size_t size)
{
        size_t remain;
        size_t now;
        errno_t rc;

        remain = sizeof(user->send_buf) - user->send_buf_used;
        while (size > 0) {
                if (remain == 0) {
                        rc = tcp_conn_send(user->conn, user->send_buf,
                            sizeof(user->send_buf));
                        if (rc != EOK)
                                return rc;

                        user->send_buf_used = 0;
                        remain = sizeof(user->send_buf);
                }

                now = min(remain, size);
                memcpy(user->send_buf + user->send_buf_used, data, now);
                user->send_buf_used += now;
                remain -= now;
                data += now;
                size -= now;
        }

        return EOK;
}

/** Send data (convert them first) to the socket, no locking.
 *
 * @param user Telnet user.
 * @param data Data buffer (not zero terminated).
 * @param size Size of @p data buffer in bytes.
 */
static errno_t telnet_user_send_data_locked(telnet_user_t *user,
    const char *data, size_t size)
{
        uint8_t *converted = malloc(3 * size + 1);
        assert(converted);
        int converted_size = 0;

        /* Convert new-lines. */
        for (size_t i = 0; i < size; i++) {
                if (data[i] == 10) {
                        converted[converted_size++] = 13;
                        converted[converted_size++] = 10;
                        user->cursor_x = 0;
                        if (user->cursor_y < (int)user->rows - 1)
                                ++user->cursor_y;
                } else {
                        converted[converted_size++] = data[i];
                        if (data[i] == '\b') {
                                user->cursor_x--;
                        } else {
                                user->cursor_x++;
                        }
                }
        }

        errno_t rc = telnet_user_send_raw_locked(user, converted,
            converted_size);
        free(converted);

        return rc;
}

/** Send data (convert them first) to the socket.
 *
 * @param user Telnet user.
 * @param data Data buffer (not zero terminated).
 * @param size Size of @p data buffer in bytes.
 */
errno_t telnet_user_send_data(telnet_user_t *user, const char *data,
    size_t size)
{
        fibril_mutex_lock(&user->send_lock);

        errno_t rc = telnet_user_send_data_locked(user, data, size);

        fibril_mutex_unlock(&user->send_lock);

        return rc;
}

/** Send raw non-printable data to the socket.
 *
 * @param user Telnet user.
 * @param data Data buffer (not zero terminated).
 * @param size Size of @p data buffer in bytes.
 */
errno_t telnet_user_send_raw(telnet_user_t *user, const char *data,
    size_t size)
{
        fibril_mutex_lock(&user->send_lock);

        errno_t rc = telnet_user_send_raw_locked(user, data, size);

        fibril_mutex_unlock(&user->send_lock);

        return rc;
}

static errno_t telnet_user_flush_locked(telnet_user_t *user)
{
        errno_t rc;

        rc = tcp_conn_send(user->conn, user->send_buf, user->send_buf_used);
        if (rc != EOK)
                return rc;

        user->send_buf_used = 0;
        return EOK;
}

errno_t telnet_user_flush(telnet_user_t *user)
{
        errno_t rc;

        fibril_mutex_lock(&user->send_lock);
        rc = telnet_user_flush_locked(user);
        fibril_mutex_unlock(&user->send_lock);
        return rc;
}

/** Update cursor X position.
 *
 * This call may result in sending control commands over socket.
 *
 * @param user Telnet user.
 * @param new_x New cursor location.
 */
void telnet_user_update_cursor_x(telnet_user_t *user, int new_x)
{
        fibril_mutex_lock(&user->send_lock);
        if (user->cursor_x - 1 == new_x) {
                char data = '\b';
                /* Ignore errors. */
                telnet_user_send_data_locked(user, &data, 1);
        }
        user->cursor_x = new_x;
        fibril_mutex_unlock(&user->send_lock);

}

/** Resize telnet session.
 *
 * @param user Telnet user
 * @param cols New number of columns
 * @param rows New number of rows
 */
void telnet_user_resize(telnet_user_t *user, unsigned cols, unsigned rows)
{
        user->cols = cols;
        user->rows = rows;
        if ((unsigned)user->cursor_x > cols - 1)
                user->cursor_x = cols - 1;
        if ((unsigned)user->cursor_y > rows - 1)
                user->cursor_y = rows - 1;
}

/**
 * @}
 */