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.\" $OpenBSD: BIO_f_base64.3,v 1.3 2016/11/06 15:52:50 jmc Exp $
.\"
.Dd $Mdocdate: November 6 2016 $
.Dt BIO_F_BASE64 3
.Os
.Sh NAME
.Nm BIO_f_base64
.Nd base64 BIO filter
.Sh SYNOPSIS
.In openssl/bio.h
.In openssl/evp.h
.Ft BIO_METHOD *
.Fo BIO_f_base64
.Fa void
.Fc
.Sh DESCRIPTION
.Fn 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.
.Pp
Base64 BIOs do not support
.Xr BIO_gets 3
or
.Xr BIO_puts 3 .
.Pp
.Xr BIO_flush 3
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.
.Pp
The flag
.Dv BIO_FLAGS_BASE64_NO_NL
can be set with
.Xr BIO_set_flags 3
to encode the data all on one line
or expect the data to be all on one line.
.Sh NOTES
Because of the format of base64 encoding the end of the encoded
block cannot always be reliably determined.
.Sh RETURN VALUES
.Fn BIO_f_base64
returns the base64 BIO method.
.Sh EXAMPLES
Base64 encode the string "Hello World\en"
and write the result to standard output:
.Bd -literal -offset indent
BIO *bio, *b64;
char message[] = "Hello World \en";
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);
.Ed
.Pp
Read Base64 encoded data from standard input
and write the decoded data to standard output:
.Bd -literal -offset indent
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);
.Ed
.Sh BUGS
The ambiguity of EOF in base64 encoded data can cause additional
data following the base64 encoded block to be misinterpreted.
.Pp
There should be some way of specifying a test that the BIO can perform
to reliably determine EOF (for example a MIME boundary).
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