base64.c

/*
 * Copyright (c) 2003 Apple Computer, Inc. All rights reserved.
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 * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
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 * This file contains Original Code and/or Modifications of Original Code
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/* Base64 encoder/decoder. Originally Apache file ap_base64.c
 */


#include "base64.h"

/* aaaack but it's fast and const should make it shared text page. */
static const unsigned char pr2six[256] =
        {
                /* ASCII table */
                64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
                64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
                64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 62, 64, 64, 64, 63,
                52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 64, 64, 64, 64, 64, 64,
                64,  0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14,
                15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 64, 64, 64, 64, 64,
                64, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
                41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 64, 64, 64, 64, 64,
                64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
                64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
                64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
                64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
                64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
                64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
                64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
                64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64
        };

int Base64decode_len(const char *bufcoded)
{
    int nbytesdecoded;
    register const unsigned char *bufin;
    register int nprbytes;

    bufin = (const unsigned char *) bufcoded;
    while (pr2six[*(bufin++)] <= 63);

    nprbytes = (int)(bufin - (const unsigned char *) bufcoded) - 1;
    nbytesdecoded = ((nprbytes + 3) / 4) * 3;

    return nbytesdecoded + 1;
}

int Base64decode(char *bufplain, const char *bufcoded)
{
    int nbytesdecoded;
    register const unsigned char *bufin;
    register unsigned char *bufout;
    register int nprbytes;

    bufin = (const unsigned char *) bufcoded;
    while (pr2six[*(bufin++)] <= 63);
    nprbytes = (int)(bufin - (const unsigned char *) bufcoded) - 1;
    nbytesdecoded = ((nprbytes + 3) / 4) * 3;

    bufout = (unsigned char *) bufplain;
    bufin = (const unsigned char *) bufcoded;

    while (nprbytes > 4) {
        *(bufout++) =
                (unsigned char) (pr2six[*bufin] << 2 | pr2six[bufin[1]] >> 4);
        *(bufout++) =
                (unsigned char) (pr2six[bufin[1]] << 4 | pr2six[bufin[2]] >> 2);
        *(bufout++) =
                (unsigned char) (pr2six[bufin[2]] << 6 | pr2six[bufin[3]]);
        bufin += 4;
        nprbytes -= 4;
    }

    /* Note: (nprbytes == 1) would be an error, so just ingore that case */
    if (nprbytes > 1) {
        *(bufout++) =
                (unsigned char) (pr2six[*bufin] << 2 | pr2six[bufin[1]] >> 4);
    }
    if (nprbytes > 2) {
        *(bufout++) =
                (unsigned char) (pr2six[bufin[1]] << 4 | pr2six[bufin[2]] >> 2);
    }
    if (nprbytes > 3) {
        *(bufout++) =
                (unsigned char) (pr2six[bufin[2]] << 6 | pr2six[bufin[3]]);
    }

    *(bufout++) = '\0';
    nbytesdecoded -= (4 - nprbytes) & 3;
    return nbytesdecoded;
}

static const char basis_64[] =
        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

int Base64encode_len(int len)
{
    return ((len + 2) / 3 * 4) + 1;
}

int Base64encode(char *encoded, const char *string, int len)
{
    int i;
    char *p;

    p = encoded;
    for (i = 0; i < len - 2; i += 3) {
        *p++ = basis_64[(string[i] >> 2) & 0x3F];
        *p++ = basis_64[((string[i] & 0x3) << 4) |
                        ((int) (string[i + 1] & 0xF0) >> 4)];
        *p++ = basis_64[((string[i + 1] & 0xF) << 2) |
                        ((int) (string[i + 2] & 0xC0) >> 6)];
        *p++ = basis_64[string[i + 2] & 0x3F];
    }
    if (i < len) {
        *p++ = basis_64[(string[i] >> 2) & 0x3F];
        if (i == (len - 1)) {
            *p++ = basis_64[((string[i] & 0x3) << 4)];
            *p++ = '=';
        }
        else {
            *p++ = basis_64[((string[i] & 0x3) << 4) |
                            ((int) (string[i + 1] & 0xF0) >> 4)];
            *p++ = basis_64[((string[i + 1] & 0xF) << 2)];
        }
        *p++ = '=';
    }

    *p++ = '\0';
    return (int)(p - encoded);
}