/*
 * The contents of this file are subject to the Mozilla Public
 * License Version 1.1 (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.mozilla.org/MPL/
 * 
 * Software distributed under the License is distributed on an "AS
 * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
 * implied. See the License for the specific language governing
 * rights and limitations under the License.
 * 
 * The Original Code is the Netscape security libraries.
 * 
 * The Initial Developer of the Original Code is Netscape
 * Communications Corporation.  Portions created by Netscape are 
 * Copyright (C) 1994-2000 Netscape Communications Corporation.  All
 * Rights Reserved.
 * 
 * Contributor(s):
 * 
 * Alternatively, the contents of this file may be used under the
 * terms of the GNU General Public License Version 2 or later (the
 * "GPL"), in which case the provisions of the GPL are applicable 
 * instead of those above.  If you wish to allow use of your 
 * version of this file only under the terms of the GPL and not to
 * allow others to use your version of this file under the MPL,
 * indicate your decision by deleting the provisions above and
 * replace them with the notice and other provisions required by
 * the GPL.  If you do not delete the provisions above, a recipient
 * may use your version of this file under either the MPL or the
 * GPL.
 */

#include "secrng.h"
#ifdef XP_WIN
#include <windows.h>
#include <time.h>
#include <io.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <stdio.h>

#ifndef _WIN32
#define VTD_Device_ID   5
#define OP_OVERRIDE     _asm _emit 0x66
#include <dos.h>
#endif

static BOOL
CurrentClockTickTime(LPDWORD lpdwHigh, LPDWORD lpdwLow)
{
#ifdef _WIN32
    LARGE_INTEGER   liCount;

    if (!QueryPerformanceCounter(&liCount))
        return FALSE;

    *lpdwHigh = liCount.u.HighPart;
    *lpdwLow = liCount.u.LowPart;
    return TRUE;

#else   /* is WIN16 */
    BOOL    bRetVal;
    FARPROC lpAPI;
    WORD    w1, w2, w3, w4;

    // Get direct access to the VTD and query the current clock tick time
    _asm {
        xor   di, di
        mov   es, di
        mov   ax, 1684h
        mov   bx, VTD_Device_ID
        int   2fh
        mov   ax, es
        or    ax, di
        jz    EnumerateFailed

        ; VTD API is available. First store the API address (the address actually
        ; contains an instruction that causes a fault, the fault handler then
        ; makes the ring transition and calls the API in the VxD)
        mov   word ptr lpAPI, di
        mov   word ptr lpAPI+2, es
        mov   ax, 100h      ; API function to VTD_Get_Real_Time
;       call  dword ptr [lpAPI]
        call  [lpAPI]

        ; Result is in EDX:EAX which we will get 16-bits at a time
        mov   w2, dx
        OP_OVERRIDE
        shr   dx,10h        ; really "shr edx, 16"
        mov   w1, dx

        mov   w4, ax
        OP_OVERRIDE
        shr   ax,10h        ; really "shr eax, 16"
        mov   w3, ax

        mov   bRetVal, 1    ; return TRUE
        jmp   EnumerateExit

      EnumerateFailed:
        mov   bRetVal, 0    ; return FALSE

      EnumerateExit:
    }

    *lpdwHigh = MAKELONG(w2, w1);
    *lpdwLow = MAKELONG(w4, w3);

    return bRetVal;
#endif  /* is WIN16 */
}

size_t RNG_GetNoise(void *buf, size_t maxbuf)
{
    DWORD   dwHigh, dwLow, dwVal;
    int     n = 0;
    int     nBytes;
    time_t  sTime;

    if (maxbuf <= 0)
        return 0;

    CurrentClockTickTime(&dwHigh, &dwLow);

    // get the maximally changing bits first
    nBytes = sizeof(dwLow) > maxbuf ? maxbuf : sizeof(dwLow);
    memcpy((char *)buf, &dwLow, nBytes);
    n += nBytes;
    maxbuf -= nBytes;

    if (maxbuf <= 0)
        return n;

    nBytes = sizeof(dwHigh) > maxbuf ? maxbuf : sizeof(dwHigh);
    memcpy(((char *)buf) + n, &dwHigh, nBytes);
    n += nBytes;
    maxbuf -= nBytes;

    if (maxbuf <= 0)
        return n;

    // get the number of milliseconds that have elapsed since Windows started
    dwVal = GetTickCount();

    nBytes = sizeof(dwVal) > maxbuf ? maxbuf : sizeof(dwVal);
    memcpy(((char *)buf) + n, &dwVal, nBytes);
    n += nBytes;
    maxbuf -= nBytes;

    if (maxbuf <= 0)
        return n;

    // get the time in seconds since midnight Jan 1, 1970
    time(&sTime);
    nBytes = sizeof(sTime) > maxbuf ? maxbuf : sizeof(sTime);
    memcpy(((char *)buf) + n, &sTime, nBytes);
    n += nBytes;

    return n;
}

static BOOL
EnumSystemFiles(void (*func)(const char *))
{
    int                 iStatus;
    char                szSysDir[_MAX_PATH];
    char                szFileName[_MAX_PATH];
#ifdef _WIN32
    struct _finddata_t  fdData;
    long                lFindHandle;
#else
    struct _find_t  fdData;
#endif

    if (!GetSystemDirectory(szSysDir, sizeof(szSysDir)))
        return FALSE;

    // tack *.* on the end so we actually look for files. this will
    // not overflow
    strcpy(szFileName, szSysDir);
    strcat(szFileName, "\\*.*");

#ifdef _WIN32
    lFindHandle = _findfirst(szFileName, &fdData);
    if (lFindHandle == -1)
        return FALSE;
#else
    if (_dos_findfirst(szFileName, _A_NORMAL | _A_RDONLY | _A_ARCH | _A_SUBDIR, &fdData) != 0)
        return FALSE;
#endif

    do {
        // pass the full pathname to the callback
        sprintf(szFileName, "%s\\%s", szSysDir, fdData.name);
        (*func)(szFileName);

#ifdef _WIN32
        iStatus = _findnext(lFindHandle, &fdData);
#else
        iStatus = _dos_findnext(&fdData);
#endif
    } while (iStatus == 0);

#ifdef _WIN32
    _findclose(lFindHandle);
#endif

    return TRUE;
}

static DWORD    dwNumFiles, dwReadEvery;

static void
CountFiles(const char *file)
{
    dwNumFiles++;
}

static void
ReadFiles(const char *file)
{
    if ((dwNumFiles % dwReadEvery) == 0)
        RNG_FileForRNG(file);

    dwNumFiles++;
}

static void
ReadSystemFiles()
{
    // first count the number of files
    dwNumFiles = 0;
    if (!EnumSystemFiles(CountFiles))
        return;

    RNG_RandomUpdate(&dwNumFiles, sizeof(dwNumFiles));

    // now read 10 files
    if (dwNumFiles == 0)
        return;

    dwReadEvery = dwNumFiles / 10;
    if (dwReadEvery == 0)
        dwReadEvery = 1;  // less than 10 files

    dwNumFiles = 0;
    EnumSystemFiles(ReadFiles);
}

void RNG_SystemInfoForRNG(void)
{
    DWORD           dwVal;
    char            buffer[256];
    int             nBytes;
#ifdef _WIN32
    MEMORYSTATUS    sMem;
    DWORD           dwSerialNum;
    DWORD           dwComponentLen;
    DWORD           dwSysFlags;
    char            volName[128];
    DWORD           dwSectors, dwBytes, dwFreeClusters, dwNumClusters;
    HANDLE          hVal;
#else
    int             iVal;
    HTASK           hTask;
    WORD            wDS, wCS;
    LPSTR           lpszEnv;
#endif

    nBytes = RNG_GetNoise(buffer, 20);  // get up to 20 bytes
    RNG_RandomUpdate(buffer, nBytes);

#ifdef _WIN32
    sMem.dwLength = sizeof(sMem);
    GlobalMemoryStatus(&sMem);                // assorted memory stats
    RNG_RandomUpdate(&sMem, sizeof(sMem));

    dwVal = GetLogicalDrives();
    RNG_RandomUpdate(&dwVal, sizeof(dwVal));  // bitfields in bits 0-25

#else
    dwVal = GetFreeSpace(0);
    RNG_RandomUpdate(&dwVal, sizeof(dwVal));

    _asm    mov wDS, ds;
    _asm    mov wCS, cs;
    RNG_RandomUpdate(&wDS, sizeof(wDS));
    RNG_RandomUpdate(&wCS, sizeof(wCS));
#endif

#ifdef _WIN32
    dwVal = sizeof(buffer);
    if (GetComputerName(buffer, &dwVal))
        RNG_RandomUpdate(buffer, dwVal);

/* XXX This is code that got yanked because of NSPR20.  We should put it
 * back someday.
 */
#ifdef notdef
    {
    POINT ptVal;
    GetCursorPos(&ptVal);
    RNG_RandomUpdate(&ptVal, sizeof(ptVal));
    }

    dwVal = GetQueueStatus(QS_ALLINPUT);      // high and low significant
    RNG_RandomUpdate(&dwVal, sizeof(dwVal));

    {
    HWND hWnd;
    hWnd = GetClipboardOwner();               // 2 or 4 bytes
    RNG_RandomUpdate((void *)&hWnd, sizeof(hWnd));
    }

    {
    UUID sUuid;
    UuidCreate(&sUuid);                       // this will fail on machines with no ethernet
    RNG_RandomUpdate(&sUuid, sizeof(sUuid));  // boards. shove the bits in regardless
    }
#endif

    hVal = GetCurrentProcess();               // 4 byte handle of current task
    RNG_RandomUpdate(&hVal, sizeof(hVal));

    dwVal = GetCurrentProcessId();            // process ID (4 bytes)
    RNG_RandomUpdate(&dwVal, sizeof(dwVal));

    volName[0] = '\0';
    buffer[0] = '\0';
    GetVolumeInformation(NULL,
                         volName,
                         sizeof(volName),
                         &dwSerialNum,
                         &dwComponentLen,
                         &dwSysFlags,
                         buffer,
                         sizeof(buffer));

    RNG_RandomUpdate(volName,         strlen(volName));
    RNG_RandomUpdate(&dwSerialNum,    sizeof(dwSerialNum));
    RNG_RandomUpdate(&dwComponentLen, sizeof(dwComponentLen));
    RNG_RandomUpdate(&dwSysFlags,     sizeof(dwSysFlags));
    RNG_RandomUpdate(buffer,          strlen(buffer));

    if (GetDiskFreeSpace(NULL, &dwSectors, &dwBytes, &dwFreeClusters, &dwNumClusters)) {
        RNG_RandomUpdate(&dwSectors,      sizeof(dwSectors));
        RNG_RandomUpdate(&dwBytes,        sizeof(dwBytes));
        RNG_RandomUpdate(&dwFreeClusters, sizeof(dwFreeClusters));
        RNG_RandomUpdate(&dwNumClusters,  sizeof(dwNumClusters));
    }

#else   /* is WIN16 */
    hTask = GetCurrentTask();
    RNG_RandomUpdate((void *)&hTask, sizeof(hTask));

    iVal = GetNumTasks();
    RNG_RandomUpdate(&iVal, sizeof(iVal));      // number of running tasks

    lpszEnv = GetDOSEnvironment();
    while (*lpszEnv != '\0') {
        RNG_RandomUpdate(lpszEnv, strlen(lpszEnv));

        lpszEnv += strlen(lpszEnv) + 1;
    }
#endif  /* is WIN16 */

    // now let's do some files
    ReadSystemFiles();

    nBytes = RNG_GetNoise(buffer, 20);  // get up to 20 bytes
    RNG_RandomUpdate(buffer, nBytes);
}

void RNG_FileForRNG(const char *filename)
{
    FILE*           file;
    int             nBytes;
    struct stat     stat_buf;
    unsigned char   buffer[1024];

    static DWORD    totalFileBytes = 0;

    /* windows doesn't initialize all the bytes in the stat buf,
     * so initialize them all here to avoid UMRs.
     */
    memset(&stat_buf, 0, sizeof stat_buf);

    if (stat((char *)filename, &stat_buf) < 0)
        return;

    RNG_RandomUpdate((unsigned char*)&stat_buf, sizeof(stat_buf));

    file = fopen((char *)filename, "r");
    if (file != NULL) {
        for (;;) {
            size_t  bytes = fread(buffer, 1, sizeof(buffer), file);

            if (bytes == 0)
                break;

            RNG_RandomUpdate(buffer, bytes);
            totalFileBytes += bytes;
            if (totalFileBytes > 250000)
                break;
        }

        fclose(file);
    }

    nBytes = RNG_GetNoise(buffer, 20);  // get up to 20 bytes
    RNG_RandomUpdate(buffer, nBytes);
}

#endif  /* is XP_WIN */