308 lines
10 KiB
C
308 lines
10 KiB
C
/*
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/ _____) _ | |
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( (____ _____ ____ _| |_ _____ ____| |__
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\____ \| ___ | (_ _) ___ |/ ___) _ \
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_____) ) ____| | | || |_| ____( (___| | | |
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(______/|_____)_|_|_| \__)_____)\____)_| |_|
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(C)2019 Semtech
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Description:
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Base64 encoding & decoding library
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License: Revised BSD License, see LICENSE.TXT file include in the project
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*/
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/* -------------------------------------------------------------------------- */
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/* --- DEPENDANCIES --------------------------------------------------------- */
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#include <stdio.h>
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#include <stdlib.h>
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#include <stdint.h>
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#include "base64.h"
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/* -------------------------------------------------------------------------- */
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/* --- PRIVATE MACROS ------------------------------------------------------- */
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#define ARRAY_SIZE(a) (sizeof(a) / sizeof((a)[0]))
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#define CRIT(a) fprintf(stderr, "\nCRITICAL file:%s line:%u msg:%s\n", __FILE__, __LINE__,a);exit(EXIT_FAILURE)
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//#define DEBUG(args...) fprintf(stderr,"debug: " args) /* diagnostic message that is destined to the user */
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#define DEBUG(args...)
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/* -------------------------------------------------------------------------- */
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/* --- PRIVATE CONSTANTS ---------------------------------------------------- */
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/* -------------------------------------------------------------------------- */
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/* --- PRIVATE MODULE-WIDE VARIABLES ---------------------------------------- */
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static char code_62 = '+'; /* RFC 1421 standard character for code 62 */
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static char code_63 = '/'; /* RFC 1421 standard character for code 63 */
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static char code_pad = '='; /* RFC 1421 padding character if padding */
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/* -------------------------------------------------------------------------- */
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/* --- PRIVATE FUNCTIONS DECLARATION ---------------------------------------- */
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/**
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@brief Convert a code in the range 0-63 to an ASCII character
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*/
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char code_to_char(uint8_t x);
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/**
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@brief Convert an ASCII character to a code in the range 0-63
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*/
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uint8_t char_to_code(char x);
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/* -------------------------------------------------------------------------- */
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/* --- PRIVATE FUNCTIONS DEFINITION ----------------------------------------- */
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char code_to_char(uint8_t x) {
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if (x <= 25) {
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return 'A' + x;
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} else if ((x >= 26) && (x <= 51)) {
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return 'a' + (x-26);
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} else if ((x >= 52) && (x <= 61)) {
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return '0' + (x-52);
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} else if (x == 62) {
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return code_62;
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} else if (x == 63) {
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return code_63;
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} else {
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DEBUG("ERROR: %i IS OUT OF RANGE 0-63 FOR BASE64 ENCODING\n", x);
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exit(EXIT_FAILURE);
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} //TODO: improve error management
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}
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uint8_t char_to_code(char x) {
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if ((x >= 'A') && (x <= 'Z')) {
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return (uint8_t)x - (uint8_t)'A';
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} else if ((x >= 'a') && (x <= 'z')) {
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return (uint8_t)x - (uint8_t)'a' + 26;
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} else if ((x >= '0') && (x <= '9')) {
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return (uint8_t)x - (uint8_t)'0' + 52;
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} else if (x == code_62) {
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return 62;
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} else if (x == code_63) {
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return 63;
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} else {
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DEBUG("ERROR: %c (0x%x) IS INVALID CHARACTER FOR BASE64 DECODING\n", x, x);
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exit(EXIT_FAILURE);
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} //TODO: improve error management
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}
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/* -------------------------------------------------------------------------- */
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/* --- PUBLIC FUNCTIONS DEFINITION ------------------------------------------ */
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int bin_to_b64_nopad(const uint8_t * in, int size, char * out, int max_len) {
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int i;
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int result_len; /* size of the result */
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int full_blocks; /* number of 3 unsigned chars / 4 characters blocks */
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int last_bytes; /* number of unsigned chars <3 in the last block */
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int last_chars; /* number of characters <4 in the last block */
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uint32_t b;
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/* check input values */
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if ((out == NULL) || (in == NULL)) {
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DEBUG("ERROR: NULL POINTER AS OUTPUT IN BIN_TO_B64\n");
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return -1;
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}
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if (size == 0) {
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*out = 0; /* null string */
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return 0;
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}
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/* calculate the number of base64 'blocks' */
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full_blocks = size / 3;
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last_bytes = size % 3;
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switch (last_bytes) {
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case 0: /* no byte left to encode */
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last_chars = 0;
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break;
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case 1: /* 1 byte left to encode -> +2 chars */
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last_chars = 2;
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break;
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case 2: /* 2 bytes left to encode -> +3 chars */
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last_chars = 3;
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break;
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default:
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CRIT("switch default that should not be possible");
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}
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/* check if output buffer is big enough */
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result_len = (4*full_blocks) + last_chars;
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if (max_len < (result_len + 1)) { /* 1 char added for string terminator */
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DEBUG("ERROR: OUTPUT BUFFER TOO SMALL IN BIN_TO_B64\n");
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return -1;
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}
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/* process all the full blocks */
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for (i=0; i < full_blocks; ++i) {
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b = (0xFF & in[3*i] ) << 16;
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b |= (0xFF & in[3*i + 1]) << 8;
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b |= 0xFF & in[3*i + 2];
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out[4*i + 0] = code_to_char((b >> 18) & 0x3F);
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out[4*i + 1] = code_to_char((b >> 12) & 0x3F);
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out[4*i + 2] = code_to_char((b >> 6 ) & 0x3F);
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out[4*i + 3] = code_to_char( b & 0x3F);
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}
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/* process the last 'partial' block and terminate string */
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i = full_blocks;
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if (last_chars == 0) {
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out[4*i] = 0; /* null character to terminate string */
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} else if (last_chars == 2) {
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b = (0xFF & in[3*i] ) << 16;
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out[4*i + 0] = code_to_char((b >> 18) & 0x3F);
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out[4*i + 1] = code_to_char((b >> 12) & 0x3F);
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out[4*i + 2] = 0; /* null character to terminate string */
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} else if (last_chars == 3) {
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b = (0xFF & in[3*i] ) << 16;
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b |= (0xFF & in[3*i + 1]) << 8;
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out[4*i + 0] = code_to_char((b >> 18) & 0x3F);
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out[4*i + 1] = code_to_char((b >> 12) & 0x3F);
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out[4*i + 2] = code_to_char((b >> 6 ) & 0x3F);
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out[4*i + 3] = 0; /* null character to terminate string */
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}
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return result_len;
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}
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int b64_to_bin_nopad(const char * in, int size, uint8_t * out, int max_len) {
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int i;
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int result_len; /* size of the result */
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int full_blocks; /* number of 3 unsigned chars / 4 characters blocks */
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int last_chars; /* number of characters <4 in the last block */
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int last_bytes; /* number of unsigned chars <3 in the last block */
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uint32_t b;
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;
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/* check input values */
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if ((out == NULL) || (in == NULL)) {
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DEBUG("ERROR: NULL POINTER AS OUTPUT OR INPUT IN B64_TO_BIN\n");
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return -1;
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}
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if (size == 0) {
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return 0;
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}
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/* calculate the number of base64 'blocks' */
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full_blocks = size / 4;
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last_chars = size % 4;
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switch (last_chars) {
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case 0: /* no char left to decode */
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last_bytes = 0;
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break;
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case 1: /* only 1 char left is an error */
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DEBUG("ERROR: ONLY ONE CHAR LEFT IN B64_TO_BIN\n");
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return -1;
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case 2: /* 2 chars left to decode -> +1 byte */
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last_bytes = 1;
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break;
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case 3: /* 3 chars left to decode -> +2 bytes */
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last_bytes = 2;
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break;
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default:
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CRIT("switch default that should not be possible");
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}
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/* check if output buffer is big enough */
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result_len = (3*full_blocks) + last_bytes;
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if (max_len < result_len) {
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DEBUG("ERROR: OUTPUT BUFFER TOO SMALL IN B64_TO_BIN\n");
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return -1;
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}
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/* process all the full blocks */
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for (i=0; i < full_blocks; ++i) {
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b = (0x3F & char_to_code(in[4*i] )) << 18;
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b |= (0x3F & char_to_code(in[4*i + 1])) << 12;
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b |= (0x3F & char_to_code(in[4*i + 2])) << 6;
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b |= 0x3F & char_to_code(in[4*i + 3]);
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out[3*i + 0] = (b >> 16) & 0xFF;
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out[3*i + 1] = (b >> 8 ) & 0xFF;
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out[3*i + 2] = b & 0xFF;
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}
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/* process the last 'partial' block */
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i = full_blocks;
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if (last_bytes == 1) {
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b = (0x3F & char_to_code(in[4*i] )) << 18;
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b |= (0x3F & char_to_code(in[4*i + 1])) << 12;
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out[3*i + 0] = (b >> 16) & 0xFF;
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if (((b >> 12) & 0x0F) != 0) {
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DEBUG("WARNING: last character contains unusable bits\n");
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}
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} else if (last_bytes == 2) {
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b = (0x3F & char_to_code(in[4*i] )) << 18;
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b |= (0x3F & char_to_code(in[4*i + 1])) << 12;
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b |= (0x3F & char_to_code(in[4*i + 2])) << 6;
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out[3*i + 0] = (b >> 16) & 0xFF;
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out[3*i + 1] = (b >> 8 ) & 0xFF;
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if (((b >> 6) & 0x03) != 0) {
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DEBUG("WARNING: last character contains unusable bits\n");
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}
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}
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return result_len;
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}
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int bin_to_b64(const uint8_t * in, int size, char * out, int max_len) {
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int ret;
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ret = bin_to_b64_nopad(in, size, out, max_len);
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if (ret == -1) {
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return -1;
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}
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switch (ret%4) {
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case 0: /* nothing to do */
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return ret;
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case 1:
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DEBUG("ERROR: INVALID UNPADDED BASE64 STRING\n");
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return -1;
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case 2: /* 2 chars in last block, must add 2 padding char */
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if (max_len >= (ret + 2 + 1)) {
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out[ret] = code_pad;
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out[ret+1] = code_pad;
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out[ret+2] = 0;
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return ret+2;
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} else {
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DEBUG("ERROR: not enough room to add padding in bin_to_b64\n");
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return -1;
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}
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case 3: /* 3 chars in last block, must add 1 padding char */
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if (max_len >= (ret + 1 + 1)) {
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out[ret] = code_pad;
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out[ret+1] = 0;
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return ret+1;
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} else {
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DEBUG("ERROR: not enough room to add padding in bin_to_b64\n");
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return -1;
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}
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default:
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CRIT("switch default that should not be possible");
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}
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}
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int b64_to_bin(const char * in, int size, uint8_t * out, int max_len) {
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if (in == NULL) {
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DEBUG("ERROR: NULL POINTER AS OUTPUT OR INPUT IN B64_TO_BIN\n");
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return -1;
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}
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if ((size%4 == 0) && (size >= 4)) { /* potentially padded Base64 */
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if (in[size-2] == code_pad) { /* 2 padding char to ignore */
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return b64_to_bin_nopad(in, size-2, out, max_len);
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} else if (in[size-1] == code_pad) { /* 1 padding char to ignore */
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return b64_to_bin_nopad(in, size-1, out, max_len);
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} else { /* no padding to ignore */
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return b64_to_bin_nopad(in, size, out, max_len);
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}
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} else { /* treat as unpadded Base64 */
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return b64_to_bin_nopad(in, size, out, max_len);
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}
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}
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/* --- EOF ------------------------------------------------------------------ */
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