BIO_F_BASE64(3ossl) OpenSSL BIO_F_BASE64(3ossl)
NAME
BIO_f_base64 - base64 BIO filter
SYNOPSIS
#include <openssl/bio.h>
#include <openssl/evp.h>
const BIO_METHOD *BIO_f_base64(void);
DESCRIPTION
BIO_f_base64(3) 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, by default output is divided to lines of length 64
characters and there is a newline at the end of output. This behavior
can be changed with BIO_FLAGS_BASE64_NO_NL flag.
For reading, first line should be at most 1024 bytes long including
newline unless the flag BIO_FLAGS_BASE64_NO_NL is set. Further input
lines can be of any length (i.e., newlines may appear anywhere in the
input) and a newline at the end of input is not needed.
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 removes all expectations on newlines in
the input data.
NOTES
Because of the format of base64 encoding the end of the encoded block
cannot always be reliably determined.
RETURN VALUES
BIO_f_base64(3) returns the base64 BIO method.
EXAMPLES
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);
BUGS
On decoding, if the flag BIO_FLAGS_BASE64_NO_NL is not set and the
first 1024 bytes of input do not include a newline character the first
two lines of input are ignored.
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
Copyright 2000-2024 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>.
3.3.2 2024-09-04 BIO_F_BASE64(3ossl)
openssl 3.3.2 - Generated Thu Sep 5 18:31:18 CDT 2024