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base32: Add base32_decode family of functions

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This commit is contained in:
Saleem Rashid 2017-05-26 19:58:40 +01:00 committed by Pavol Rusnak
parent c4db240e70
commit 0912c4d215
3 changed files with 124 additions and 1 deletions
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114
base32.c
View File

@ -22,10 +22,16 @@
#include "base32.h"
#include <string.h>
const char *BASE32_ALPHABET_RFC4648 = "ABCDEFGHIJKLMNOPQRSTUVWXYZ23456789";
static inline void base32_5to8(const uint8_t *in, uint8_t length, uint8_t *out);
static inline bool base32_8to5(const uint8_t *in, uint8_t length, uint8_t *out, const char *alphabet);
static inline void base32_8to5_raw(const uint8_t *in, uint8_t length, uint8_t *out);
static inline int base32_encode_character(uint8_t decoded, const char *alphabet);
static inline int base32_decode_character(char encoded, const char *alphabet);
bool base32_encode(const uint8_t *in, size_t inlen, char *out, size_t outlen, const char *alphabet) {
size_t length = base32_encoded_length(inlen);
@ -45,6 +51,19 @@ bool base32_encode(const uint8_t *in, size_t inlen, char *out, size_t outlen, co
return true;
}
uint8_t *base32_decode(const char *in, size_t inlen, uint8_t *out, size_t outlen, const char *alphabet) {
size_t length = base32_decoded_length(inlen);
if (outlen < length) {
return NULL;
}
if (!base32_decode_unsafe((uint8_t *) in, inlen, (uint8_t *) out, alphabet)) {
return NULL;
}
return &out[length];
}
void base32_encode_unsafe(const uint8_t *in, size_t inlen, uint8_t *out) {
uint8_t remainder = inlen % 5;
size_t limit = inlen - remainder;
@ -57,6 +76,24 @@ void base32_encode_unsafe(const uint8_t *in, size_t inlen, uint8_t *out) {
if (remainder) base32_5to8(&in[i], remainder, &out[j]);
}
bool base32_decode_unsafe(const uint8_t *in, size_t inlen, uint8_t *out, const char *alphabet) {
uint8_t remainder = inlen % 8;
size_t limit = inlen - remainder;
size_t i, j;
for (i = 0, j = 0; i < limit; i += 8, j += 5) {
if (!base32_8to5(&in[i], 8, &out[j], alphabet)) {
return false;
}
}
if (remainder && !base32_8to5(&in[i], remainder, &out[j], alphabet)) {
return false;
}
return true;
}
size_t base32_encoded_length(size_t inlen) {
uint8_t remainder = inlen % 5;
@ -98,6 +135,61 @@ void base32_5to8(const uint8_t *in, uint8_t length, uint8_t *out) {
}
}
bool base32_8to5(const uint8_t *in, uint8_t length, uint8_t *out, const char *alphabet) {
if (length == 1 || length == 3 || length == 6 || length > 8) {
return false;
}
if (alphabet) {
uint8_t decoded[length];
for (size_t i = 0; i < length; i++) {
int ret = base32_decode_character(in[i], alphabet);
if (ret == -1) {
return false;
} else {
decoded[i] = ret;
}
}
base32_8to5_raw(decoded, length, out);
} else {
base32_8to5_raw(in, length, out);
}
return true;
}
void base32_8to5_raw(const uint8_t *in, uint8_t length, uint8_t *out) {
if (length >= 2) {
out[0] = (in[0] << 3);
out[0] |= (in[1] >> 2);
}
if (length >= 4) {
out[1] = (in[1] & 3) << 6;
out[1] |= (in[2] << 1);
out[1] |= (in[3] >> 4);
}
if (length >= 5) {
out[2] = (in[3] & 15) << 4;
out[2] |= (in[4] >> 1);
}
if (length >= 7) {
out[3] = (in[4] & 1) << 7;
out[3] |= (in[5] << 2);
out[3] |= (in[6] >> 3);
}
if (length >= 8) {
out[4] = (in[6] & 7) << 5;
out[4] |= (in[7] & 31);
}
}
int base32_encode_character(uint8_t decoded, const char *alphabet) {
if (decoded >> 5) {
return -1;
@ -113,3 +205,25 @@ int base32_encode_character(uint8_t decoded, const char *alphabet) {
return alphabet[decoded];
}
int base32_decode_character(char encoded, const char *alphabet) {
if (alphabet == BASE32_ALPHABET_RFC4648) {
if (encoded >= 'A' && encoded <= 'Z') {
return encoded - 'A';
} else if (encoded >= 'a' && encoded <= 'z') {
return encoded - 'a';
} else if (encoded >= '2' && encoded <= '7') {
return encoded - '2' + 26;
} else {
return -1;
}
}
const char *occurrence = strchr(alphabet, encoded);
if (occurrence) {
return occurrence - alphabet;
} else {
return -1;
}
}

3
base32.h
View File

@ -32,6 +32,9 @@ extern const char *BASE32_ALPHABET_RFC4648;
bool base32_encode(const uint8_t *in, size_t inlen, char *out, size_t outlen, const char *alphabet);
void base32_encode_unsafe(const uint8_t *in, size_t inlen, uint8_t *out);
uint8_t *base32_decode(const char *in, size_t inlen, uint8_t *out, size_t outlen, const char *alphabet);
bool base32_decode_unsafe(const uint8_t *in, size_t inlen, uint8_t *out, const char *alphabet);
size_t base32_encoded_length(size_t inlen);
size_t base32_decoded_length(size_t inlen);

8
test_check.c
View File

@ -527,8 +527,14 @@ START_TEST(test_base32_rfc4648)
ck_assert_int_eq(outlen, base32_encoded_length(inlen));
ck_assert_int_eq(inlen, base32_decoded_length(outlen));
base32_encode((uint8_t *) in, inlen, buffer, sizeof(buffer), BASE32_ALPHABET_RFC4648);
ck_assert(base32_encode((uint8_t *) in, inlen, buffer, sizeof(buffer), BASE32_ALPHABET_RFC4648));
ck_assert_str_eq(buffer, out);
char *ret = (char *) base32_decode(out, outlen, (uint8_t *) buffer, sizeof(buffer), BASE32_ALPHABET_RFC4648);
ck_assert(ret);
*ret = '\0';
ck_assert_str_eq(buffer, in);
}
}
END_TEST