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=pod
=head1 NAME
BIO_find_type, BIO_next - BIO chain traversal
=head1 SYNOPSIS
#include <openssl/bio.h>
BIO * BIO_find_type(BIO *b,int bio_type);
BIO * BIO_next(BIO *b);
#define BIO_method_type(b) ((b)->method->type)
#define BIO_TYPE_NONE 0
#define BIO_TYPE_MEM (1|0x0400)
#define BIO_TYPE_FILE (2|0x0400)
#define BIO_TYPE_FD (4|0x0400|0x0100)
#define BIO_TYPE_SOCKET (5|0x0400|0x0100)
#define BIO_TYPE_NULL (6|0x0400)
#define BIO_TYPE_SSL (7|0x0200)
#define BIO_TYPE_MD (8|0x0200)
#define BIO_TYPE_BUFFER (9|0x0200)
#define BIO_TYPE_CIPHER (10|0x0200)
#define BIO_TYPE_BASE64 (11|0x0200)
#define BIO_TYPE_CONNECT (12|0x0400|0x0100)
#define BIO_TYPE_ACCEPT (13|0x0400|0x0100)
#define BIO_TYPE_PROXY_CLIENT (14|0x0200)
#define BIO_TYPE_PROXY_SERVER (15|0x0200)
#define BIO_TYPE_NBIO_TEST (16|0x0200)
#define BIO_TYPE_NULL_FILTER (17|0x0200)
#define BIO_TYPE_BER (18|0x0200)
#define BIO_TYPE_BIO (19|0x0400)
#define BIO_TYPE_DESCRIPTOR 0x0100
#define BIO_TYPE_FILTER 0x0200
#define BIO_TYPE_SOURCE_SINK 0x0400
=head1 DESCRIPTION
The BIO_find_type() searches for a BIO of a given type in a chain, starting
at BIO B<b>. If B<type> is a specific type (such as BIO_TYPE_MEM) then a search
is made for a BIO of that type. If B<type> is a general type (such as
B<BIO_TYPE_SOURCE_SINK>) then the next matching BIO of the given general type is
searched for. BIO_find_type() returns the next matching BIO or NULL if none is
found.
Note: not all the B<BIO_TYPE_*> types above have corresponding BIO implementations.
BIO_next() returns the next BIO in a chain. It can be used to traverse all BIOs
in a chain or used in conjunction with BIO_find_type() to find all BIOs of a
certain type.
BIO_method_type() returns the type of a BIO.
=head1 RETURN VALUES
BIO_find_type() returns a matching BIO or NULL for no match.
BIO_next() returns the next BIO in a chain.
BIO_method_type() returns the type of the BIO B<b>.
=head1 NOTES
BIO_next() was added to OpenSSL 0.9.6 to provide a 'clean' way to traverse a BIO
chain or find multiple matches using BIO_find_type(). Previous versions had to
use:
next = bio->next_bio;
=head1 BUGS
BIO_find_type() in OpenSSL 0.9.5a and earlier could not be safely passed a
NULL pointer for the B<b> argument.
=head1 EXAMPLE
Traverse a chain looking for digest BIOs:
BIO *btmp;
btmp = in_bio; /* in_bio is chain to search through */
do {
btmp = BIO_find_type(btmp, BIO_TYPE_MD);
if(btmp == NULL) break; /* Not found */
/* btmp is a digest BIO, do something with it ...*/
...
btmp = BIO_next(btmp);
} while(btmp);
=head1 SEE ALSO
TBA

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=pod
=head1 NAME
BIO_read, BIO_write, BIO_gets, BIO_puts - BIO I/O functions
=head1 SYNOPSIS
#include <openssl/bio.h>
int BIO_read(BIO *b, void *buf, int len);
int BIO_gets(BIO *b,char *buf, int size);
int BIO_write(BIO *b, const void *buf, int len);
int BIO_puts(BIO *b,const char *buf);
=head1 DESCRIPTION
BIO_read() attempts to read B<len> bytes from BIO B<b> and places
the data in B<buf>.
BIO_gets() performs the BIOs "gets" operation and places the data
in B<buf>. Usually this operation will attempt to read a line of data
from the BIO of maximum length B<len>. There are exceptions to this
however, for example BIO_gets() on a digest BIO will calculate and
return the digest and other BIOs may not support BIO_gets() at all.
BIO_write() attempts to write B<len> bytes from B<buf> to BIO B<b>.
BIO_puts() attempts to write a null terminated string B<buf> to BIO B<b>
=head1 RETURN VALUES
All these functions return either the amount of data successfully read or
written (if the return value is positive) or that no data was successfully
read or written (if the result is zero or negative).
=head1 NOTES
A negative or zero return is not necessarily an indication of an error. In
particular when the source/sink is non-blocking or of a certain type (for
example an SSL BIO can retry even if the underlying connection is blocking)
it may merely be an indication that no data is currently available and that
the application should retry the operation later. L<BIO_should_retry(3)|BIO_should_retry(3)>
can be called to determine the precise cause.
If the BIO_gets() function is not supported by a BIO then it possible to
work around this by adding a buffering BIO L<BIO_f_buffer(3)|BIO_f_buffer(3)>
to the chain.
=head1 SEE ALSO
TBA