base64.c

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/* base64.c : base-64 / MIME encode/decode */
/* PUBLIC DOMAIN - Jon Mayo - November 13, 2003 */
#include <esp8266.h>
#include "base64.h"

static const uint8_t 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 ICACHE_FLASH_ATTR 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 ICACHE_FLASH_ATTR 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 io;
}

//Only need decode functions for now.
#if 0

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

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)];
}


int base64_encode(size_t in_len, const unsigned char *in, size_t out_len, char *out) {
    unsigned ii, io;
    uint_least32_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++]=base64enc_tab[(v>>rem)&63];
        }
    }
    if(rem) {
        v<<=(6-rem);
        if(io>=out_len) return -1; /* truncation is failure */
        out[io++]=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 io;
}

#endif