BIO_f_base64 - base64 BIO filter
#include <openssl/bio.h>
#include <openssl/evp.h>
const BIO_METHOD *BIO_f_base64(void);
BIO_f_base64() returns the base64 BIO method. This is a filter BIO that
base64 encodes any data written through it and decodes any data read through
it.
Base64 BIOs do not support
BIO_gets() or
BIO_puts().
For writing, output is by default divided to lines of length 64 characters and
there is always a newline at the end of output.
For reading, first line should be at most 1024 characters long. If it is longer
then it is ignored completely. Other input lines can be of any length. There
must be a newline at the end of input.
This behavior can be changed with BIO_FLAGS_BASE64_NO_NL flag.
BIO_flush() on a base64 BIO that is being written through is used to
signal that no more data is to be encoded: this is used to flush the final
block through the BIO.
The flag BIO_FLAGS_BASE64_NO_NL can be set with
BIO_set_flags(). For
writing, it causes all data to be written on one line without newline at the
end. For reading, it expects the data to be all on one line (with or without a
trailing newline).
Because of the format of base64 encoding the end of the encoded block cannot
always be reliably determined.
BIO_f_base64() returns the base64 BIO method.
Base64 encode the string "Hello World\n" and write the result to
standard output:
BIO *bio, *b64;
char message[] = "Hello World \n";
b64 = BIO_new(BIO_f_base64());
bio = BIO_new_fp(stdout, BIO_NOCLOSE);
BIO_push(b64, bio);
BIO_write(b64, message, strlen(message));
BIO_flush(b64);
BIO_free_all(b64);
Read Base64 encoded data from standard input and write the decoded data to
standard output:
BIO *bio, *b64, *bio_out;
char inbuf[512];
int inlen;
b64 = BIO_new(BIO_f_base64());
bio = BIO_new_fp(stdin, BIO_NOCLOSE);
bio_out = BIO_new_fp(stdout, BIO_NOCLOSE);
BIO_push(b64, bio);
while ((inlen = BIO_read(b64, inbuf, 512)) > 0)
BIO_write(bio_out, inbuf, inlen);
BIO_flush(bio_out);
BIO_free_all(b64);
The ambiguity of EOF in base64 encoded data can cause additional data following
the base64 encoded block to be misinterpreted.
There should be some way of specifying a test that the BIO can perform to
reliably determine EOF (for example a MIME boundary).
Copyright 2000-2022 The OpenSSL Project Authors. All Rights Reserved.
Licensed under the Apache License 2.0 (the "License"). You may not use
this file except in compliance with the License. You can obtain a copy in the
file LICENSE in the source distribution or at
<
https://www.openssl.org/source/license.html>.