247 lines
4.1 KiB
C
247 lines
4.1 KiB
C
/* base64_dec.c */
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/*
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* This file is part of the AVR-Crypto-Lib.
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* Copyright (C) 2006, 2007, 2008 Daniel Otte (daniel.otte@rub.de)
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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/**
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* base64 decoder (RFC3548)
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* Author: Daniel Otte
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* License: GPLv3
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*
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*
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*/
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#include <stdint.h>
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#include "base64_dec.h"
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#include "test_src/cli.h"
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/*
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#define USE_GCC_EXTENSION
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*/
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#if 1
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#ifdef USE_GCC_EXTENSION
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static
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int ascii2bit6(char a){
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switch(a){
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case 'A'...'Z':
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return a-'A';
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case 'a'...'z':
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return a-'a'+26;
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case '0'...'9':
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return a-'0'+52;
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case '+':
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case '-':
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return 62;
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case '/':
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case '_':
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return 63;
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default:
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return -1;
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}
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}
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#else
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static
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uint8_t ascii2bit6(char a){
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int r;
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switch(a>>4){
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case 0x5:
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case 0x4:
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r=a-'A';
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if(r<0 || r>25){
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return -1;
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} else {
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return r;
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}
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case 0x7:
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case 0x6:
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r=a-'a';
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if(r<0 || r>25){
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return -1;
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} else {
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return r+26;
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}
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break;
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case 0x3:
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if(a>'9')
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return -1;
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return a-'0'+52;
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default:
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break;
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}
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switch (a){
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case '+':
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case '-':
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return 62;
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case '/':
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case '_':
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return 63;
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default:
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return 0xff;
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}
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}
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#endif
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#else
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static
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uint8_t ascii2bit6(uint8_t a){
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if(a>='A' && a<='Z'){
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return a-'A';
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} else {
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if(a>='a' && a<= 'z'){
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return a-'a'+26;
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} else {
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if(a>='0' && a<='9'){
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return a-'0'+52;
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} else {
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if(a=='+' || a=='-'){
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return 62;
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} else {
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if(a=='/' || a=='_'){
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return 63;
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} else {
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return 0xff;
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}
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}
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}
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}
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}
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}
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#endif
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int base64_binlength(char* str, uint8_t strict){
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int l=0;
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uint8_t term=0;
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for(;;){
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if(*str=='\0')
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break;
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if(*str=='\n' || *str=='\r'){
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str++;
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continue;
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}
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if(*str=='='){
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term++;
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str++;
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if(term==2){
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break;
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}
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continue;
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}
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if(term)
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return -1;
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if(ascii2bit6(*str)==-1){
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if(strict)
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return -1;
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} else {
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l++;
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}
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str++;
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}
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switch(term){
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case 0:
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if(l%4!=0)
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return -1;
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return l/4*3;
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case 1:
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if(l%4!=3)
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return -1;
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return (l+1)/4*3-1;
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case 2:
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if(l%4!=2)
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return -1;
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return (l+2)/4*3-2;
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default:
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return -1;
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}
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}
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/*
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|543210543210543210543210|
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|765432107654321076543210|
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. . . .
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|54321054|32105432|10543210|
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|76543210|76543210|76543210|
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*/
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int base64dec(void* dest, char* b64str, uint8_t strict){
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uint8_t buffer[4];
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uint8_t idx=0;
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uint8_t term=0;
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for(;;){
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// cli_putstr_P(PSTR("\r\n DBG: got 0x"));
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// cli_hexdump(b64str, 1);
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buffer[idx]= ascii2bit6(*b64str);
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// cli_putstr_P(PSTR(" --> 0x"));
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// cli_hexdump(buffer+idx, 1);
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if(buffer[idx]==0xFF){
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if(*b64str=='='){
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term++;
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b64str++;
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if(term==2)
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goto finalize; /* definitly the end */
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}else{
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if(*b64str == '\0'){
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goto finalize; /* definitly the end */
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}else{
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if(*b64str == '\r' || *b64str == '\n' || !(strict)){
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b64str++; /* charcters that we simply ignore */
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}else{
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return -1;
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}
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}
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}
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}else{
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if(term)
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return -1; /* this happens if we get a '=' in the stream */
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idx++;
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b64str++;
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}
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if(idx==4){
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((uint8_t*)dest)[0] = buffer[0]<<2 | buffer[1]>>4;
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((uint8_t*)dest)[1] = buffer[1]<<4 | buffer[2]>>2;
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((uint8_t*)dest)[2] = buffer[2]<<6 | buffer[3];
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dest = (uint8_t*)dest +3;
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idx=0;
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}
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}
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finalize:
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/* the final touch */
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if(idx==0)
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return 0;
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if(term==1){
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((uint8_t*)dest)[0] = buffer[0]<<2 | buffer[1]>>4;
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((uint8_t*)dest)[1] = buffer[1]<<4 | buffer[2]>>2;
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return 0;
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}
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if(term==2){
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((uint8_t*)dest)[0] = buffer[0]<<2 | buffer[1]>>4;
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return 0;
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}
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return -1;
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}
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