source: titan/minidlna-1.0.22/tivo_utils.c @ 13567

/* MiniDLNA media server
 * Copyright (C) 2009  Justin Maggard
 *
 * This file is part of MiniDLNA.
 *
 * MiniDLNA is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * MiniDLNA is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with MiniDLNA. If not, see <http://www.gnu.org/licenses/>.
 */
#include "config.h"
#ifdef TIVO_SUPPORT
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include <ctype.h>
#include <sqlite3.h>
#include "tivo_utils.h"

/* This function based on byRequest */
char *
decodeString(char * string, int inplace)
{
        if( !string )
                return NULL;
        int alloc = (int)strlen(string)+1;
        char * ns = NULL;
        unsigned char in;
        int strindex=0;
        long hex;

        if( !inplace )
        {
                if( !(ns = malloc(alloc)) )
                        return NULL;
        }

        while(--alloc > 0)
        {
                in = *string;
                if((in == '%') && isxdigit(string[1]) && isxdigit(string[2]))
                {
                        /* this is two hexadecimal digits following a '%' */
                        char hexstr[3];
                        char *ptr;
                        hexstr[0] = string[1];
                        hexstr[1] = string[2];
                        hexstr[2] = 0;

                        hex = strtol(hexstr, &ptr, 16);

                        in = (unsigned char)hex; /* this long is never bigger than 255 anyway */
                        if( inplace )
                        {
                                *string = in;
                                memmove(string+1, string+3, alloc-2);
                        }
                        else
                        {
                                string+=2;
                        }
                        alloc-=2;
                }
                if( !inplace )
                        ns[strindex++] = in;
                string++;
        }
        if( inplace )
        {
                if( ns )
                        free(ns);
                return string;
        }
        else
        {
                ns[strindex] = '\0'; /* terminate it */
                return ns;
        }
}

/* These next functions implement a repeatable random function with a user-provided seed */
static int
seedRandomByte(uint32_t seed)
{
        unsigned char t;

        if( !sqlite3Prng.isInit )
        {
                int i;
                char k[256];
                sqlite3Prng.j = 0;
                sqlite3Prng.i = 0;
                memset(&k, '\0', sizeof(k));
                memcpy(&k, &seed, 4);
                for(i=0; i<256; i++)
                        sqlite3Prng.s[i] = i;
                for(i=0; i<256; i++)
                {
                        sqlite3Prng.j += sqlite3Prng.s[i] + k[i];
                        t = sqlite3Prng.s[sqlite3Prng.j];
                        sqlite3Prng.s[sqlite3Prng.j] = sqlite3Prng.s[i];
                        sqlite3Prng.s[i] = t;
                }
                sqlite3Prng.isInit = 1;
        }
        /* Generate and return single random byte */
        sqlite3Prng.i++;
        t = sqlite3Prng.s[sqlite3Prng.i];
        sqlite3Prng.j += t;
        sqlite3Prng.s[sqlite3Prng.i] = sqlite3Prng.s[sqlite3Prng.j];
        sqlite3Prng.s[sqlite3Prng.j] = t;
        t += sqlite3Prng.s[sqlite3Prng.i];

        return sqlite3Prng.s[t];
}

void
seedRandomness(int n, void *pbuf, uint32_t seed)
{
        unsigned char *zbuf = pbuf;

        while( n-- )
                *(zbuf++) = seedRandomByte(seed);
}

void
TiVoRandomSeedFunc(sqlite3_context *context, int argc, sqlite3_value **argv)
{
        sqlite_int64 r, seed;

        if( argc != 1 || sqlite3_value_type(argv[0]) != SQLITE_INTEGER )
                return;
        seed = sqlite3_value_int64(argv[0]);
        seedRandomness(sizeof(r), &r, seed);
        sqlite3_result_int64(context, r);
}
#endif