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  • /*
     * Realmedia RTSP protocol (RDT) support.
     * Copyright (c) 2007 Ronald S. Bultje
     *
     * This file is part of FFmpeg.
     *
     * FFmpeg is free software; you can redistribute it and/or
     * modify it under the terms of the GNU Lesser General Public
     * License as published by the Free Software Foundation; either
     * version 2.1 of the License, or (at your option) any later version.
     *
     * FFmpeg 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
     * Lesser General Public License for more details.
     *
     * You should have received a copy of the GNU Lesser General Public
     * License along with FFmpeg; if not, write to the Free Software
     * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
     */
    
    /**
     * @file rdt.c
     * @brief Realmedia RTSP protocol (RDT) support
     * @author Ronald S. Bultje <rbultje@ronald.bitfreak.net>
     */
    
    #include "avformat.h"
    #include "libavutil/avstring.h"
    #include "rdt.h"
    #include "libavutil/base64.h"
    #include "libavutil/md5.h"
    #include "rm.h"
    #include "internal.h"
    
    void
    ff_rdt_calc_response_and_checksum(char response[41], char chksum[9],
                                      const char *challenge)
    {
        int ch_len = strlen (challenge), i;
        unsigned char zres[16],
            buf[64] = { 0xa1, 0xe9, 0x14, 0x9d, 0x0e, 0x6b, 0x3b, 0x59 };
    #define XOR_TABLE_SIZE 37
        const unsigned char xor_table[XOR_TABLE_SIZE] = {
            0x05, 0x18, 0x74, 0xd0, 0x0d, 0x09, 0x02, 0x53,
            0xc0, 0x01, 0x05, 0x05, 0x67, 0x03, 0x19, 0x70,
            0x08, 0x27, 0x66, 0x10, 0x10, 0x72, 0x08, 0x09,
            0x63, 0x11, 0x03, 0x71, 0x08, 0x08, 0x70, 0x02,
            0x10, 0x57, 0x05, 0x18, 0x54 };
    
        /* some (length) checks */
        if (ch_len == 40) /* what a hack... */
            ch_len = 32;
        else if (ch_len > 56)
            ch_len = 56;
        memcpy(buf + 8, challenge, ch_len);
    
        /* xor challenge bytewise with xor_table */
        for (i = 0; i < XOR_TABLE_SIZE; i++)
            buf[8 + i] ^= xor_table[i];
    
        av_md5_sum(zres, buf, 64);
        ff_data_to_hex(response, zres, 16);
        for (i=0;i<32;i++) response[i] = tolower(response[i]);
    
        /* add tail */
        strcpy (response + 32, "01d0a8e3");
    
        /* calculate checksum */
        for (i = 0; i < 8; i++)
            chksum[i] = response[i * 4];
        chksum[8] = 0;
    }