libssl/man/SSL_get_ciphers.3

.\" $OpenBSD: SSL_get_ciphers.3,v 1.11 2020/09/16 07:25:15 schwarze Exp $
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.\" The original file was written by Lutz Jaenicke <jaenicke@openssl.org>,
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.\" Kazuki Yamaguchi <k@rhe.jp>, and Benjamin Kaduk <bkaduk@akamai.com>.
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.Dd $Mdocdate: September 16 2020 $
.Dt SSL_GET_CIPHERS 3
.Os
.Sh NAME
.Nm SSL_get_ciphers ,
.Nm SSL_CTX_get_ciphers ,
.Nm SSL_get1_supported_ciphers ,
.Nm SSL_get_client_ciphers ,
.Nm SSL_get_cipher_list
.Nd get lists of available SSL_CIPHERs
.Sh SYNOPSIS
.In openssl/ssl.h
.Ft STACK_OF(SSL_CIPHER) *
.Fn SSL_get_ciphers "const SSL *ssl"
.Ft STACK_OF(SSL_CIPHER) *
.Fn SSL_CTX_get_ciphers "const SSL_CTX *ctx"
.Ft STACK_OF(SSL_CIPHER) *
.Fn SSL_get1_supported_ciphers "SSL *ssl"
.Ft STACK_OF(SSL_CIPHER) *
.Fn SSL_get_client_ciphers "const SSL *ssl"
.Ft const char *
.Fn SSL_get_cipher_list "const SSL *ssl" "int priority"
.Sh DESCRIPTION
.Fn SSL_get_ciphers
returns the stack of available
.Vt SSL_CIPHER Ns s
for
.Fa ssl ,
sorted by preference.
.Pp
.Fn SSL_CTX_get_ciphers
returns the stack of available
.Vt SSL_CIPHER Ns s
for
.Fa ctx .
.Pp
.Fn SSL_get1_supported_ciphers
returns a stack of enabled
.Vt SSL_CIPHER Ns s
for
.Fa ssl
as it would be sent in a ClientHello, sorted by preference.
The list depends on settings like the cipher list, the supported
protocol versions, the security level, and the enabled signature
algorithms.
The list of ciphers that would be sent in a ClientHello can differ
from the list of ciphers that would be acceptable when acting as a
server.
For example,
additional ciphers may be usable by a server if there is a gap in the
list of supported protocols, and some ciphers may not be usable by a
server if there is not a suitable certificate configured.
.Pp
.Fn SSL_get_client_ciphers
returns the stack of available
.Vt SSL_CIPHER Ns s
matching the list received from the client on
.Fa ssl .
.Pp
The details of the ciphers obtained by
.Fn SSL_get_ciphers ,
.Fn SSL_CTX_get_ciphers ,
.Fn SSL_get1_supported_ciphers ,
and
.Fn SSL_get_client_ciphers
can be obtained using the
.Xr SSL_CIPHER_get_name 3
family of functions.
.Pp
.Fn SSL_get_cipher_list
is deprecated \(em use
.Fn SSL_get_ciphers
instead \(em and badly misnamed; it does not return a list
but the name of one element of the return value of
.Fn SSL_get_ciphers ,
with the index given by the
.Fa priority
argument.
Passing 0 selects the cipher with the highest priority.
To iterate over all available ciphers in decreasing priority,
repeatedly increment the argument by 1 until
.Dv NULL
is returned.
.Sh RETURN VALUES
.Fn SSL_get_ciphers
returns an internal pointer to a list of ciphers or
.Dv NULL
if
.Fa ssl
is
.Dv NULL
or if no ciphers are available.
The returned pointer may not only become invalid when
.Fa ssl
is destroyed or when
.Xr SSL_set_cipher_list 3
is called on it, but also when the
.Vt SSL_CTX
object in use by
.Fa ssl
at the time of the call is freed or when
.Xr SSL_CTX_set_cipher_list 3
is called on that context object.
.Pp
.Fn SSL_CTX_get_ciphers
returns an internal pointer to a list of ciphers or
.Dv NULL
if
.Fa ctx
is
.Dv NULL
or if no ciphers are available.
The returned pointer becomes invalid when
.Fa ctx
is destroyed or when
.Xr SSL_CTX_set_cipher_list 3
is called on it.
.Pp
.Fn SSL_get1_supported_ciphers
returns a newly allocated list of ciphers or
.Dv NULL
if
.Fa ssl
is
.Dv NULL ,
if no ciphers are available, or if an error occurs.
When the returned pointer is no longer needed, the caller is
responsible for freeing it using
.Fn sk_SSL_CIPHER_free .
.Pp
.Fn SSL_get_client_ciphers
returns an internal pointer to a list of ciphers or
.Dv NULL
if
.Fa ssl
is
.Dv NULL ,
has no active session,
or is not operating in server mode.
The returned pointer becomes invalid when the
.Vt SSL_SESSION
object is destroyed, even if the
.Fa ssl
object remains valid.
It may also become invalid in other circumstances,
for example when processing a new ClientHello.
.Pp
.Fn SSL_get_cipher_list
returns an internal pointer to a string or
.Dv NULL
if
.Fa ssl
is
.Dv NULL ,
if no ciphers are available, or if
.Fa priority
is greater than or equal to the number of available ciphers.
.Sh SEE ALSO
.Xr ssl 3 ,
.Xr SSL_CIPHER_get_name 3 ,
.Xr SSL_CTX_set_cipher_list 3
.Sh HISTORY
.Fn SSL_get_cipher_list
first appeared in SSLeay 0.5.2.
.Fn SSL_get_ciphers
first appeared in SSLeay 0.8.0.
Both functions have been available since
.Ox 2.4 .
.Pp
.Fn SSL_CTX_get_ciphers
first appeared in OpenSSL 1.1.0 and has been available since
.Ox 6.3 .
.Pp
.Fn SSL_get1_supported_ciphers
and
.Fn SSL_get_client_ciphers
first appeared in OpenSSL 1.1.0 and has been available since
.Ox 6.5 .