.\" $OpenBSD: BIO_meth_new.3,v 1.5 2018/07/09 09:52:18 tb Exp $
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.\" The original file was written by Matt Caswell <matt@openssl.org>
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.Dd $Mdocdate: July 9 2018 $
.Dt BIO_METH_NEW 3
.Os
.Sh NAME
.Nm BIO_get_new_index ,
.Nm BIO_meth_new ,
.Nm BIO_meth_free ,
.Nm BIO_meth_get_write ,
.Nm BIO_meth_set_write ,
.Nm BIO_meth_get_read ,
.Nm BIO_meth_set_read ,
.Nm BIO_meth_get_puts ,
.Nm BIO_meth_set_puts ,
.Nm BIO_meth_get_gets ,
.Nm BIO_meth_set_gets ,
.Nm BIO_meth_get_ctrl ,
.Nm BIO_meth_set_ctrl ,
.Nm BIO_meth_get_create ,
.Nm BIO_meth_set_create ,
.Nm BIO_meth_get_destroy ,
.Nm BIO_meth_set_destroy ,
.Nm BIO_meth_get_callback_ctrl ,
.Nm BIO_meth_set_callback_ctrl
.Nd manipulate BIO_METHOD structures
.Sh SYNOPSIS
.In openssl/bio.h
.Ft int
.Fn BIO_get_new_index void
.Ft BIO_METHOD *
.Fo BIO_meth_new
.Fa "int type"
.Fa "const char *name"
.Fc
.Ft void
.Fo BIO_meth_free
.Fa "BIO_METHOD *biom"
.Fc
.Ft int
.Fn "(*BIO_meth_get_write(const BIO_METHOD *biom))" "BIO *" "const char *" int
.Ft int
.Fo BIO_meth_set_write
.Fa "BIO_METHOD *biom"
.Fa "int (*write)(BIO *, const char *, int)"
.Fc
.Ft int
.Fn "(*BIO_meth_get_read(const BIO_METHOD *biom))" "BIO *" "char *" int
.Ft int
.Fo BIO_meth_set_read
.Fa "BIO_METHOD *biom"
.Fa "int (*read)(BIO *, char *, int)"
.Fc
.Ft int
.Fn "(*BIO_meth_get_puts(const BIO_METHOD *biom))" "BIO *" "const char *"
.Ft int
.Fo BIO_meth_set_puts
.Fa "BIO_METHOD *biom"
.Fa "int (*puts)(BIO *, const char *)"
.Fc
.Ft int
.Fn "(*BIO_meth_get_gets(const BIO_METHOD *biom))" "BIO *" "char *" int
.Ft int
.Fo BIO_meth_set_gets
.Fa "BIO_METHOD *biom"
.Fa "int (*gets)(BIO *, char *, int)"
.Fc
.Ft long
.Fn "(*BIO_meth_get_ctrl(const BIO_METHOD *biom))" "BIO *" int long "void *"
.Ft int
.Fo BIO_meth_set_ctrl
.Fa "BIO_METHOD *biom"
.Fa "long (*ctrl)(BIO *, int, long, void *)"
.Fc
.Ft int
.Fn "(*BIO_meth_get_create(const BIO_METHOD *biom))" "BIO *"
.Ft int
.Fo BIO_meth_set_create
.Fa "BIO_METHOD *biom"
.Fa "int (*create)(BIO *)"
.Fc
.Ft int
.Fn "(*BIO_meth_get_destroy(const BIO_METHOD *biom))" "BIO *"
.Ft int
.Fo BIO_meth_set_destroy
.Fa "BIO_METHOD *biom"
.Fa "int (*destroy)(BIO *)"
.Fc
.Ft long
.Fo "(*BIO_meth_get_callback_ctrl(const BIO_METHOD *biom))"
.Fa "BIO *"
.Fa int
.Fa "BIO_info_cb *"
.Fc
.Ft int
.Fo BIO_meth_set_callback_ctrl
.Fa "BIO_METHOD *biom"
.Fa "long (*callback_ctrl)(BIO *, int, BIO_info_cb *)"
.Fc
.Sh DESCRIPTION
The
.Vt BIO_METHOD
structure stores function pointers implementing a
.Vt BIO
type.
See
.Xr BIO_new 3
for more information about
.Vt BIO
objects.
.Pp
.Fn BIO_meth_new
creates a new
.Vt BIO_METHOD
structure.
It requires a unique integer
.Fa type ;
use
.Fn BIO_get_new_index
to get the value for
.Fa type .
Currently, the user can only create up to 127 different BIO types, and
.Fa type
is limited to the range 129\(en255.
The
.Fa name
pointer is stored in the structure and will not be freed by
.Fn BIO_meth_free .
.Pp
The standard BIO types are listed in
.In openssl/bio.h .
Some examples include
.Dv BIO_TYPE_BUFFER
and
.Dv BIO_TYPE_CIPHER .
The
.Fa type
of filter BIOs should have the
.Dv BIO_TYPE_FILTER
bit set.
Source/sink BIOs should have the
.Dv BIO_TYPE_SOURCE_SINK
bit set.
File descriptor based BIOs (e.g. socket, fd, connect, accept etc.\&)
should additionally have the
.Dv BIO_TYPE_DESCRIPTOR
bit set.
See
.Xr BIO_find_type 3
for more information.
.Pp
.Fn BIO_meth_free
is an alias for
.Xr free 3 .
.Pp
.Fn BIO_meth_get_write ,
.Fn BIO_meth_set_write ,
.Fn BIO_meth_get_read ,
and
.Fn BIO_meth_set_read
get and set the functions
.Fa write
and
.Fa read
used for writing and reading arbitrary length data to and from the
.Vt BIO .
These functions are called from
.Xr BIO_write 3
and
.Xr BIO_read 3 ,
respectively.
The parameters and return values of
.Fa write
and
.Fa read
have the same meaning as for
.Xr BIO_write 3
and
.Xr BIO_read 3 .
.Pp
.Fn BIO_meth_get_puts
and
.Fn BIO_meth_set_puts
get and set the function
.Fa puts
used for writing a NUL-terminated string to the
.Vt BIO .
This function is called from
.Xr BIO_puts 3 .
The parameters and the return value of
.Fa puts
have the same meaning as for
.Xr BIO_puts 3 .
.Pp
.Fn BIO_meth_get_gets
and
.Fn BIO_meth_set_gets
get and set the function
.Fa gets
used for reading a line of data from the
.Vt BIO .
This function is called from
.Xr BIO_gets 3 .
The parameters and the return value of
.Fa gets
have the same meaning as for
.Xr BIO_gets 3 .
.Pp
.Fn BIO_meth_get_ctrl
and
.Fn BIO_meth_set_ctrl
get and set the function
.Fa ctrl
used for processing control messages in the
.Vt BIO .
This function is called from
.Xr BIO_ctrl 3 .
The parameters and return value of
.Fa ctrl
have the same meaning as for
.Xr BIO_ctrl 3 .
.Pp
.Fn BIO_meth_get_create
and
.Fn BIO_meth_set_create
get and set a function
.Fa create
used while initializing a new instance of the
.Vt BIO .
This function is called from
.Xr BIO_new 3 .
The
.Xr BIO_new 3
function allocates the memory for the new
.Vt BIO ,
and a pointer to this newly allocated structure is passed
as the parameter to
.Fa create .
.Pp
.Fn BIO_meth_get_destroy
and
.Fn BIO_meth_set_destroy
get and set a function
.Fa destroy
used while destroying an instance of a
.Vt BIO .
This function is called from
.Xr BIO_free 3 .
A pointer to the
.Vt BIO
to be destroyed is passed as the parameter.
The
.Fa destroy
function is intended to perform clean-up specific to the
.Vt BIO
.Fa type .
The memory for the
.Vt BIO
itself must not be freed by this function.
.Pp
.Fn BIO_meth_get_callback_ctrl
and
.Fn BIO_meth_set_callback_ctrl
get and set the function
.Fa callback_ctrl
used for processing callback control messages in the
.Vt BIO .
This function is called from
.Xr BIO_callback_ctrl 3 .
The parameters and return value of
.Fa callback_ctrl
have the same meaning as for
.Xr BIO_callback_ctrl 3 .
.Sh RETURN VALUES
.Fn BIO_get_new_index
returns the new BIO type value or \-1 if an error occurs.
.Pp
.Fn BIO_meth_new
returns the new
.Vt BIO_METHOD
structure or
.Dv NULL
if an error occurs.
.Pp
The
.Fn BIO_meth_set_*
functions return 1 on success or 0 on error.
Currently, they cannot fail.
.Pp
The
.Fn BIO_meth_get_*
functions return function pointers.
.Sh SEE ALSO
.Xr BIO_ctrl 3 ,
.Xr BIO_find_type 3 ,
.Xr BIO_new 3 ,
.Xr BIO_read 3
.Sh HISTORY
These functions first appeared in OpenSSL 1.1.0
and have been available since
.Ox 6.3 .