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/* $OpenBSD: encoding.c,v 1.10 2021/11/24 15:24:16 claudio Exp $ */
/*
* Copyright (c) 2020 Claudio Jeker <claudio@openbsd.org>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <sys/stat.h>
#include <err.h>
#include <errno.h>
#include <ctype.h>
#include <fcntl.h>
#include <limits.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <openssl/evp.h>
#include "extern.h"
/*
* Load file from disk and return the buffer and size.
*/
unsigned char *
load_file(const char *name, size_t *len)
{
unsigned char *buf = NULL;
struct stat st;
ssize_t n;
size_t size;
int fd, saved_errno;
*len = 0;
if ((fd = open(name, O_RDONLY)) == -1)
return NULL;
if (fstat(fd, &st) != 0)
goto err;
if (st.st_size <= 0 || st.st_size > MAX_FILE_SIZE) {
errno = EFBIG;
goto err;
}
size = (size_t)st.st_size;
if ((buf = malloc(size)) == NULL)
goto err;
n = read(fd, buf, size);
if (n == -1)
goto err;
if ((size_t)n != size) {
errno = EIO;
goto err;
}
close(fd);
*len = size;
return buf;
err:
saved_errno = errno;
close(fd);
free(buf);
errno = saved_errno;
return NULL;
}
/*
* Return the size of the data blob in outlen for an inlen sized base64 buffer.
* Returns 0 on success and -1 if inlen would overflow an int.
*/
int
base64_decode_len(size_t inlen, size_t *outlen)
{
*outlen = 0;
if (inlen >= INT_MAX - 3)
return -1;
*outlen = ((inlen + 3) / 4) * 3 + 1;
return 0;
}
/*
* Decode base64 encoded string into binary buffer returned in out.
* The out buffer size is stored in outlen.
* Returns 0 on success or -1 for any errors.
*/
int
base64_decode(const unsigned char *in, size_t inlen,
unsigned char **out, size_t *outlen)
{
static EVP_ENCODE_CTX *ctx;
unsigned char *to;
size_t tolen;
int evplen;
if (ctx == NULL && (ctx = EVP_ENCODE_CTX_new()) == NULL)
err(1, "EVP_ENCODE_CTX_new");
*out = NULL;
*outlen = 0;
if (base64_decode_len(inlen, &tolen) == -1)
return -1;
if ((to = malloc(tolen)) == NULL)
return -1;
evplen = tolen;
EVP_DecodeInit(ctx);
if (EVP_DecodeUpdate(ctx, to, &evplen, in, inlen) == -1)
goto fail;
*outlen = evplen;
if (EVP_DecodeFinal(ctx, to + evplen, &evplen) == -1)
goto fail;
*outlen += evplen;
*out = to;
return 0;
fail:
free(to);
return -1;
}
/*
* Return the size of the base64 blob in outlen for a inlen sized binary buffer.
* Returns 0 on success and -1 if inlen would overflow the calculation.
*/
int
base64_encode_len(size_t inlen, size_t *outlen)
{
*outlen = 0;
if (inlen >= INT_MAX / 2)
return -1;
*outlen = ((inlen + 2) / 3) * 4 + 1;
return 0;
}
/*
* Encode a binary buffer into a base64 encoded string returned in out.
* Returns 0 on success or -1 for any errors.
*/
int
base64_encode(const unsigned char *in, size_t inlen, char **out)
{
unsigned char *to;
size_t tolen;
*out = NULL;
if (base64_encode_len(inlen, &tolen) == -1)
return -1;
if ((to = malloc(tolen)) == NULL)
return -1;
EVP_EncodeBlock(to, in, inlen);
*out = to;
return 0;
}
/*
* Convert binary buffer of size dsz into an upper-case hex-string.
* Returns pointer to the newly allocated string. Function can't fail.
*/
char *
hex_encode(const unsigned char *in, size_t insz)
{
const char hex[] = "0123456789ABCDEF";
size_t i;
char *out;
if ((out = calloc(2, insz + 1)) == NULL)
err(1, NULL);
for (i = 0; i < insz; i++) {
out[i * 2] = hex[in[i] >> 4];
out[i * 2 + 1] = hex[in[i] & 0xf];
}
out[i * 2] = '\0';
return out;
}
/*
* Hex decode hexstring into the supplied buffer.
* Return 0 on success else -1, if buffer too small or bad encoding.
*/
int
hex_decode(const char *hexstr, char *buf, size_t len)
{
unsigned char ch, r;
size_t pos = 0;
int i;
while (*hexstr) {
r = 0;
for (i = 0; i < 2; i++) {
ch = hexstr[i];
if (isdigit(ch))
ch -= '0';
else if (islower(ch))
ch -= ('a' - 10);
else if (isupper(ch))
ch -= ('A' - 10);
else
return -1;
if (ch > 0xf)
return -1;
r = r << 4 | ch;
}
if (pos < len)
buf[pos++] = r;
else
return -1;
hexstr += 2;
}
return 0;
}
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