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#include "base64.h"
#include <openssl/evp.h>
#include <errno.h>
#include <stddef.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
static void remove_lf(char *b64)
{
while ((b64 = strchr(b64, '\n')))
memcpy(b64, b64 + 1, strlen(b64));
}
static size_t base64len(const size_t n)
{
/* Read EVP_EncodeInit(3) for further reference. */
return ((n / 48) * 65) + (n % 48 ? 1 + ((n / 3) + 1) * 4 : 0);
}
static size_t decodedlen(const size_t n)
{
return ((n / 64) * 48) + (n % 64 ? (n / 4) * 3 : 0);
}
char *base64_encode(const void *const buf, const size_t n)
{
EVP_ENCODE_CTX *const ctx = EVP_ENCODE_CTX_new();
char *ret = NULL;
unsigned char *b64 = NULL;
if (!ctx)
{
fprintf(stderr, "%s: EVP_ENCODE_CTX_new failed\n", __func__);
goto end;
}
const size_t b64len = base64len(n);
if (!(b64 = malloc(b64len + 1)))
{
fprintf(stderr, "%s: malloc(3): %s\n", __func__, strerror(errno));
goto end;
}
EVP_EncodeInit(ctx);
size_t rem = n, done = 0;
int outl = b64len;
while (rem)
{
const size_t i = n - rem, inl = rem > 48 ? 48 : rem;
const unsigned char *const in = buf;
if (!EVP_EncodeUpdate(ctx, &b64[done], &outl, &in[i], inl))
{
fprintf(stderr, "%s: EVP_EncodeUpdate failed\n", __func__);
goto end;
}
done += outl;
rem -= inl;
}
EVP_EncodeFinal(ctx, b64, &outl);
ret = (char *)b64;
remove_lf(ret);
end:
if (!ret)
free(b64);
EVP_ENCODE_CTX_free(ctx);
return ret;
}
void *base64_decode(const char *const b64, size_t *const n)
{
void *ret = NULL;
const size_t len = strlen(b64), dlen = decodedlen(len);
EVP_ENCODE_CTX *const ctx = EVP_ENCODE_CTX_new();
unsigned char *const buf = malloc(dlen);
if (!buf)
{
fprintf(stderr, "%s: malloc(3): %s\n", __func__, strerror(errno));
goto end;
}
else if (!ctx)
{
fprintf(stderr, "%s: EVP_ENCODE_CTX_new failed\n", __func__);
goto end;
}
EVP_DecodeInit(ctx);
size_t rem = len, done = 0;
int outl = dlen;
while (rem)
{
const size_t i = len - rem, inl = rem > 64 ? 64 : rem;
const unsigned char *const in = (const unsigned char *)b64;
if (EVP_DecodeUpdate(ctx, &buf[done], &outl, &in[i], inl) < 0)
{
fprintf(stderr, "%s: EVP_EncodeUpdate failed\n", __func__);
goto end;
}
done += outl;
rem -= inl;
}
EVP_DecodeFinal(ctx, buf, &outl);
*n = done;
ret = buf;
end:
if (!ret)
free(buf);
EVP_ENCODE_CTX_free(ctx);
return ret;
}
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