/* base64.c : base-64 / MIME encode/decode */
/* PUBLIC DOMAIN - Jon Mayo - November 13, 2003 */
#include "base64.h"
#include <stdint.h>
#include <ctype.h>

static const int base64dec_tab[256] = {
        255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
        255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
        255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 62, 255, 255, 255, 63,
        52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 255, 255, 255, 0, 255, 255,
        255, 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, 255, 255, 255, 255, 255,
        255, 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, 255, 255, 255, 255, 255,
        255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
        255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
        255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
        255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
        255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
        255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
        255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
        255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
};

#if 0
static int base64decode(const char in[4], char out[3]) {
    uint8_t v[4];

    v[0]=base64dec_tab[(unsigned)in[0]];
    v[1]=base64dec_tab[(unsigned)in[1]];
    v[2]=base64dec_tab[(unsigned)in[2]];
    v[3]=base64dec_tab[(unsigned)in[3]];

    out[0]=(v[0]<<2)|(v[1]>>4);
    out[1]=(v[1]<<4)|(v[2]>>2);
    out[2]=(v[2]<<6)|(v[3]);
    return (v[0]|v[1]|v[2]|v[3])!=255 ? in[3]=='=' ? in[2]=='=' ? 1 : 2 : 3 : 0;
}
#endif

/* decode a base64 string in one shot */
int __attribute__((weak)) base64_decode(size_t in_len, const char *in, size_t out_len, unsigned char *out)
{
    unsigned int ii, io;
    uint32_t v;
    unsigned int rem;

    for (io = 0, ii = 0, v = 0, rem = 0; ii < in_len; ii++) {
        unsigned char ch;
        if (isspace((int) in[ii])) { continue; }
        if (in[ii] == '=') { break; } /* stop at = */
        ch = base64dec_tab[(unsigned int) in[ii]];
        if (ch == 255) { break; } /* stop at a parse error */
        v = (v << 6) | ch;
        rem += 6;
        if (rem >= 8) {
            rem -= 8;
            if (io >= out_len) return -1; /* truncation is failure */
            out[io++] = (v >> rem) & 255;
        }
    }
    if (rem >= 8) {
        rem -= 8;
        if (io >= out_len) { return -1; } /* truncation is failure */
        out[io++] = (v >> rem) & 255;
    }
    return (int) io;
}

static const uint8_t base64enc_tab[64] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

#if 0
void base64encode(const unsigned char in[3], unsigned char out[4], int count) {
    out[0]=base64enc_tab[(in[0]>>2)];
    out[1]=base64enc_tab[((in[0]&3)<<4)|(in[1]>>4)];
    out[2]=count<2 ? '=' : base64enc_tab[((in[1]&15)<<2)|(in[2]>>6)];
    out[3]=count<3 ? '=' : base64enc_tab[(in[2]&63)];
}
#endif

int __attribute__((weak)) base64_encode(size_t in_len, const unsigned char *in, size_t out_len, char *out)
{
    unsigned ii, io;
    uint32_t v;
    unsigned rem;

    for (io = 0, ii = 0, v = 0, rem = 0; ii < in_len; ii++) {
        unsigned char ch;
        ch = in[ii];
        v = (v << 8) | ch;
        rem += 8;
        while (rem >= 6) {
            rem -= 6;
            if (io >= out_len) { return -1; } /* truncation is failure */
            out[io++] = (char) base64enc_tab[(v >> rem) & 63];
        }
    }
    if (rem) {
        v <<= (6 - rem);
        if (io >= out_len) { return -1; } /* truncation is failure */
        out[io++] = (char) base64enc_tab[v & 63];
    }
    while (io & 3) {
        if (io >= out_len) { return -1; } /* truncation is failure */
        out[io++] = '=';
    }
    if (io >= out_len) { return -1; } /* no room for null terminator */
    out[io] = 0;
    return (int) io;
}