base64.cpp

Go to the documentation of this file.

/*
   +----------------------------------------------------------------------+
   | PHP HTML Embedded Scripting Language Version 3.0                     |
   +----------------------------------------------------------------------+
   | Copyright (c) 1997-2000 PHP Development Team (See Credits file)      |
   +----------------------------------------------------------------------+
   | This program is free software; you can redistribute it and/or modify |
   | it under the terms of one of the following licenses:                 |
   |                                                                      |
   |  A) the GNU General Public License as published by the Free Software |
   |     Foundation; either version 2 of the License, or (at your option) |
   |     any later version.                                               |
   |                                                                      |
   |  B) the PHP License as published by the PHP Development Team and     |
   |     included in the distribution in the file: LICENSE                |
   |                                                                      |
   | This program 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 both licenses referred to here.   |
   | If you did not, or have any questions about PHP licensing, please    |
   | contact core@php.net.                                                |
   +----------------------------------------------------------------------+
   | Author: Jim Winstead (jimw@php.net)                                  |
   +----------------------------------------------------------------------+
   */
 
#include "utils/base64.h"
 
#include <cstdlib>
#include <cstring>
 
static char base64_table[] =
{
    'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M',
    'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
    'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
    'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
    '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/', '\0'
};
static char base64_pad = '=';
 
unsigned char *php3_base64_encode(const unsigned char *string, int length, int *ret_length)
{
    const unsigned char *current = string;
    int i = 0;
    auto *result = (unsigned char *)malloc(((length + 3 - length % 3) * 4 / 3 + 1) * sizeof(char));
 
    while (length > 2)
    { /* keep going until we have less than 24 bits */
        result[i++] = base64_table[current[0] >> 2];
        result[i++] = base64_table[((current[0] & 0x03) << 4) + (current[1] >> 4)];
        result[i++] = base64_table[((current[1] & 0x0f) << 2) + (current[2] >> 6)];
        result[i++] = base64_table[current[2] & 0x3f];
 
        current += 3;
        length -= 3; /* we just handle 3 octets of data */
    }
 
    /* now deal with the tail end of things */
    if (length != 0)
    {
        result[i++] = base64_table[current[0] >> 2];
        if (length > 1)
        {
            result[i++] = base64_table[((current[0] & 0x03) << 4) + (current[1] >> 4)];
            result[i++] = base64_table[(current[1] & 0x0f) << 2];
            result[i++] = base64_pad;
        }
        else
        {
            result[i++] = base64_table[(current[0] & 0x03) << 4];
            result[i++] = base64_pad;
            result[i++] = base64_pad;
        }
    }
    if (ret_length)
    {
        *ret_length = i;
    }
    result[i] = '\0';
    return result;
}
 
/* as above, but backwards. :) */
unsigned char *php3_base64_decode(const unsigned char *string, int length, int *ret_length)
{
    const unsigned char *current = string;
    int ch, i = 0, j = 0, k;
    char *chp;
 
    auto *result = (unsigned char *)malloc(length + 1);
 
    if (result == nullptr)
    {
        return nullptr;
    }
 
    /* run through the whole string, converting as we go */
    while ((ch = *current++) != '\0')
    {
        if (ch == base64_pad) break;
 
        /* When Base64 gets POSTed, all pluses are interpreted as spaces.
           This line changes them back.  It's not exactly the Base64 spec,
           but it is completely compatible with it (the spec says that
           spaces are invalid).  This will also save many people considerable
           headache.  - Turadg Aleahmad <turadg@wise.berkeley.edu>
           */
 
        if (ch == ' ') ch = '+';
 
        chp = strchr(base64_table, ch);
        if (chp == nullptr) continue;
        ch = chp - base64_table;
 
        switch(i % 4)
        {
            case 0:
                result[j] = ch << 2;
                break;
            case 1:
                result[j++] |= ch >> 4;
                result[j] = (ch & 0x0f) << 4;
                break;
            case 2:
                result[j++] |= ch >>2;
                result[j] = (ch & 0x03) << 6;
                break;
            case 3:
                result[j++] |= ch;
                break;
        }
        i++;
    }
 
    k = j;
    /* mop things up if we ended on a boundary */
    if (ch == base64_pad)
    {
        switch(i % 4)
        {
            case 0:
            case 1:
                free(result);
                return nullptr;
            case 2:
                k++;
            case 3:
                result[k++] = 0;
        }
    }
    if (ret_length)
    {
        *ret_length = j;
    }
    result[k] = '\0';
    return result;
}