/**
 * xrdp: A Remote Desktop Protocol server.
 *
 * Copyright (C) Thomas Goddard 2012
 * Copyright (C) Jay Sorg 2012
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/* do not use os_calls in here */

#define LOG_LEVEL 1
#define LLOG(_level, _args) \
    do { if (_level < LOG_LEVEL) { ErrorF _args ; } } while (0)
#define LLOGLN(_level, _args) \
    do { if (_level < LOG_LEVEL) { printf _args ; printf("\n"); } } while (0)

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <sys/un.h>

#include "xrdpapi.h"

struct wts_obj
{
    int fd;
    int status;
    char name[8];
    char dname[128];
    int display_num;
    int flags;
};

/*****************************************************************************/
static int
get_display_num_from_display(char *display_text)
{
    int index;
    int mode;
    int host_index;
    int disp_index;
    int scre_index;
    char host[256];
    char disp[256];
    char scre[256];

    index = 0;
    host_index = 0;
    disp_index = 0;
    scre_index = 0;
    mode = 0;

    while (display_text[index] != 0)
    {
        if (display_text[index] == ':')
        {
            mode = 1;
        }
        else if (display_text[index] == '.')
        {
            mode = 2;
        }
        else if (mode == 0)
        {
            host[host_index] = display_text[index];
            host_index++;
        }
        else if (mode == 1)
        {
            disp[disp_index] = display_text[index];
            disp_index++;
        }
        else if (mode == 2)
        {
            scre[scre_index] = display_text[index];
            scre_index++;
        }

        index++;
    }

    host[host_index] = 0;
    disp[disp_index] = 0;
    scre[scre_index] = 0;
    return atoi(disp);
}

/*****************************************************************************/
void *
WTSVirtualChannelOpen(void *hServer, unsigned int SessionId,
                      const char *pVirtualName)
{
    if (hServer != WTS_CURRENT_SERVER_HANDLE)
    {
        return 0;
    }

    return WTSVirtualChannelOpenEx(SessionId, pVirtualName, 0);
}

/*****************************************************************************/
static int
can_send(int sck, int millis)
{
    struct timeval time;
    fd_set wfds;
    int select_rv;

    FD_ZERO(&wfds);
    FD_SET(sck, &wfds);
    time.tv_sec = millis / 1000;
    time.tv_usec = (millis * 1000) % 1000000;
    select_rv = select(sck + 1, 0, &wfds, 0, &time);

    if (select_rv > 0)
    {
        return 1;
    }

    return 0;
}

/*****************************************************************************/
static int
can_recv(int sck, int millis)
{
    struct timeval time;
    fd_set rfds;
    int select_rv;

    FD_ZERO(&rfds);
    FD_SET(sck, &rfds);
    time.tv_sec = millis / 1000;
    time.tv_usec = (millis * 1000) % 1000000;
    select_rv = select(sck + 1, &rfds, 0, 0, &time);

    if (select_rv > 0)
    {
        return 1;
    }

    return 0;
}

/*****************************************************************************/
static int
send_init(struct wts_obj *wts)
{
    char initmsg[64];

    memset(initmsg, 0, 64);
    strncpy(initmsg, wts->name, 8);
    initmsg[16] = (wts->flags >> 0) & 0xff;
    initmsg[17] = (wts->flags >> 8) & 0xff;
    initmsg[18] = (wts->flags >> 16) & 0xff;
    initmsg[19] = (wts->flags >> 24) & 0xff;
    LLOGLN(10, ("send_init: sending %s", initmsg));

    if (!can_send(wts->fd, 500))
    {
        return 1;
    }

    if (send(wts->fd, initmsg, 64, 0) != 64)
    {
        return 1;
    }

    LLOGLN(10, ("send_init: send ok!"));
    return 0;
}

/*****************************************************************************/
void *
WTSVirtualChannelOpenEx(unsigned int SessionId,
                        const char *pVirtualName,
                        unsigned int flags)
{
    struct wts_obj *wts;
    char *display_text;
    struct sockaddr_un s;
    int bytes;
    unsigned long llong;

    if (SessionId != WTS_CURRENT_SESSION)
    {
        LLOGLN(0, ("WTSVirtualChannelOpenEx: SessionId bad"));
        return 0;
    }

    wts = (struct wts_obj *)malloc(sizeof(struct wts_obj));
    memset(wts, 0, sizeof(struct wts_obj));
    wts->fd = -1;
    wts->flags = flags;
    display_text = getenv("DISPLAY");

    if (display_text != 0)
    {
        wts->display_num = get_display_num_from_display(display_text);
    }

    if (wts->display_num > 0)
    {
        wts->fd = socket(AF_UNIX, SOCK_STREAM, 0);
        /* set non blocking */
        llong = fcntl(wts->fd, F_GETFL);
        llong = llong | O_NONBLOCK;
        fcntl(wts->fd, F_SETFL, llong);
        /* connect to session chansrv */
        memset(&s, 0, sizeof(struct sockaddr_un));
        s.sun_family = AF_UNIX;
        bytes = sizeof(s.sun_path);
        snprintf(s.sun_path, bytes - 1, "/tmp/.xrdp/xrdpapi_%d", wts->display_num);
        s.sun_path[bytes - 1] = 0;
        bytes = sizeof(struct sockaddr_un);

        if (connect(wts->fd, (struct sockaddr *)&s, bytes) == 0)
        {
            LLOGLN(10, ("WTSVirtualChannelOpenEx: connected ok, name %s", pVirtualName));
            strncpy(wts->name, pVirtualName, 8);

            /* wait for connection to complete and send init */
            if (send_init(wts) == 0)
            {
                /* all ok */
                wts->status = 1;
            }
        }
    }
    else
    {
        LLOGLN(0, ("WTSVirtualChannelOpenEx: display is 0"));
    }

    return wts;
}

/*****************************************************************************/
int
WTSVirtualChannelWrite(void *hChannelHandle, const char *Buffer,
                       unsigned int Length, unsigned int *pBytesWritten)
{
    struct wts_obj *wts;
    int error;
    int lerrno;

    wts = (struct wts_obj *)hChannelHandle;

    if (wts == 0)
    {
        return 0;
    }

    if (wts->status != 1)
    {
        return 0;
    }

    if (can_send(wts->fd, 0))
    {
        error = send(wts->fd, Buffer, Length, 0);

        if (error == -1)
        {
            lerrno = errno;

            if ((lerrno == EWOULDBLOCK) || (lerrno == EAGAIN) ||
                    (lerrno == EINPROGRESS))
            {
                *pBytesWritten = 0;
                return 1;
            }

            return 0;
        }
        else if (error == 0)
        {
            return 0;
        }
        else if (error > 0)
        {
            *pBytesWritten = error;
            return 1;
        }
    }

    *pBytesWritten = 0;
    return 1;
}

/*****************************************************************************/
int
WTSVirtualChannelRead(void *hChannelHandle, unsigned int TimeOut,
                      char *Buffer, unsigned int BufferSize,
                      unsigned int *pBytesRead)
{
    struct wts_obj *wts;
    int error;
    int lerrno;

    wts = (struct wts_obj *)hChannelHandle;

    if (wts == 0)
    {
        return 0;
    }

    if (wts->status != 1)
    {
        return 0;
    }

    if (can_recv(wts->fd, TimeOut))
    {
        error = recv(wts->fd, Buffer, BufferSize, 0);

        if (error == -1)
        {
            lerrno = errno;

            if ((lerrno == EWOULDBLOCK) || (lerrno == EAGAIN) ||
                    (lerrno == EINPROGRESS))
            {
                *pBytesRead = 0;
                return 1;
            }

            return 0;
        }
        else if (error == 0)
        {
            return 0;
        }
        else if (error > 0)
        {
            *pBytesRead = error;
            return 1;
        }
    }

    *pBytesRead = 0;
    return 1;
}

/*****************************************************************************/
int
WTSVirtualChannelClose(void *hChannelHandle)
{
    struct wts_obj *wts;

    wts = (struct wts_obj *)hChannelHandle;

    if (wts == 0)
    {
        return 0;
    }

    if (wts->fd != -1)
    {
        close(wts->fd);
    }

    free(wts);
    return 1;
}

/*****************************************************************************/
int
WTSVirtualChannelQuery(void *hChannelHandle, WTS_VIRTUAL_CLASS WtsVirtualClass,
                       void **ppBuffer, unsigned int *pBytesReturned)
{
    struct wts_obj *wts;

    wts = (struct wts_obj *)hChannelHandle;

    if (wts == 0)
    {
        return 0;
    }

    if (wts->status != 1)
    {
        return 0;
    }

    if (WtsVirtualClass == WTSVirtualFileHandle)
    {
        *pBytesReturned = 4;
        *ppBuffer = malloc(4);
        memcpy(*ppBuffer, &(wts->fd), 4);
    }

    return 1;
}

/*****************************************************************************/
void
WTSFreeMemory(void *pMemory)
{
    if (pMemory != 0)
    {
        free(pMemory);
    }
}