Function md_util_base64url_decode

modules/md/md_util.c:1157–1205

#define BASE64URL_CHAR(x)    BASE64URL_CHARS[ (unsigned int)(x) & 0x3fu ]
   
apr_size_t md_util_base64url_decode(md_data_t *decoded, const char *encoded, 
                                    apr_pool_t *pool)
{
    const unsigned char *e = (const unsigned char *)encoded;
    const unsigned char *p = e;
    unsigned char *d;
    unsigned int n;
    long len, mlen, remain, i;
    
    while (*p && BASE64URL_UINT6[ *p ] != N6) {
        ++p;
    }
    len = (int)(p - e);
    mlen = (len/4)*4;
    decoded->data = apr_pcalloc(pool, (apr_size_t)len + 1);
    
    i = 0;
    d = (unsigned char*)decoded->data;
    for (; i < mlen; i += 4) {
        n = ((BASE64URL_UINT6[ e[i+0] ] << 18) +
             (BASE64URL_UINT6[ e[i+1] ] << 12) +
             (BASE64URL_UINT6[ e[i+2] ] << 6) +
             (BASE64URL_UINT6[ e[i+3] ]));
        *d++ = (unsigned char)(n >> 16);
        *d++ = (unsigned char)(n >> 8 & 0xffu);
        *d++ = (unsigned char)(n & 0xffu);
    }
    remain = len - mlen;
    switch (remain) {
        case 2:
            n = ((BASE64URL_UINT6[ e[mlen+0] ] << 18) +
                 (BASE64URL_UINT6[ e[mlen+1] ] << 12));
            *d++ = (unsigned char)(n >> 16);
            remain = 1;
            break;
        case 3:
            n = ((BASE64URL_UINT6[ e[mlen+0] ] << 18) +
                 (BASE64URL_UINT6[ e[mlen+1] ] << 12) +
                 (BASE64URL_UINT6[ e[mlen+2] ] << 6));
            *d++ = (unsigned char)(n >> 16);
            *d++ = (unsigned char)(n >> 8 & 0xffu);
            remain = 2;
            break;
        default: /* do nothing */
            break;
    }
    decoded->len = (apr_size_t)(mlen/4*3 + remain);
    return decoded->len; 
}

const char *md_util_base64url_encode(const md_data_t *data, apr_pool_t *pool)
{