xref: /openssl/doc/man3/SSL_get_value_uint.pod (revision b317583f) 
1=pod
2
3=head1 NAME
4
5SSL_get_value_uint, SSL_set_value_uint, SSL_get_generic_value_uint,
6SSL_set_generic_value_uint, SSL_get_feature_request_uint,
7SSL_set_feature_request_uint, SSL_get_feature_peer_request_uint,
8SSL_get_feature_negotiated_uint, SSL_get_quic_stream_bidi_local_avail,
9SSL_get_quic_stream_bidi_remote_avail, SSL_get_quic_stream_uni_local_avail,
10SSL_get_quic_stream_uni_remote_avail, SSL_VALUE_CLASS_GENERIC,
11SSL_VALUE_CLASS_FEATURE_REQUEST, SSL_VALUE_CLASS_FEATURE_PEER_REQUEST,
12SSL_VALUE_CLASS_FEATURE_NEGOTIATED, SSL_VALUE_QUIC_STREAM_BIDI_LOCAL_AVAIL,
13SSL_VALUE_QUIC_STREAM_BIDI_REMOTE_AVAIL, SSL_VALUE_QUIC_STREAM_UNI_LOCAL_AVAIL,
14SSL_VALUE_QUIC_STREAM_UNI_REMOTE_AVAIL, SSL_VALUE_QUIC_IDLE_TIMEOUT,
15SSL_VALUE_EVENT_HANDLING_MODE,
16SSL_VALUE_EVENT_HANDLING_MODE_INHERIT,
17SSL_VALUE_EVENT_HANDLING_MODE_EXPLICIT,
18SSL_VALUE_EVENT_HANDLING_MODE_IMPLICIT,
19SSL_get_event_handling_mode,
20SSL_set_event_handling_mode,
21SSL_VALUE_STREAM_WRITE_BUF_SIZE,
22SSL_get_stream_write_buf_size,
23SSL_VALUE_STREAM_WRITE_BUF_USED,
24SSL_get_stream_write_buf_used,
25SSL_VALUE_STREAM_WRITE_BUF_AVAIL,
26SSL_get_stream_write_buf_avail -
27manage negotiable features and configuration values for a SSL object
28
29=head1 SYNOPSIS
30
31 #include <openssl/ssl.h>
32
33 int SSL_get_value_uint(SSL *ssl, uint32_t class_, uint32_t id,
34                        uint64_t *value);
35 int SSL_set_value_uint(SSL *ssl, uint32_t class_, uint32_t id,
36                        uint64_t value);
37
38 #define SSL_VALUE_CLASS_GENERIC
39 #define SSL_VALUE_CLASS_FEATURE_REQUEST
40 #define SSL_VALUE_CLASS_FEATURE_PEER_REQUEST
41 #define SSL_VALUE_CLASS_FEATURE_NEGOTIATED
42
43 #define SSL_VALUE_QUIC_STREAM_BIDI_LOCAL_AVAIL
44 #define SSL_VALUE_QUIC_STREAM_BIDI_REMOTE_AVAIL
45 #define SSL_VALUE_QUIC_STREAM_UNI_LOCAL_AVAIL
46 #define SSL_VALUE_QUIC_STREAM_UNI_REMOTE_AVAIL
47 #define SSL_VALUE_QUIC_IDLE_TIMEOUT
48
49 #define SSL_VALUE_EVENT_HANDLING_MODE
50 #define SSL_VALUE_EVENT_HANDLING_MODE_INHERIT
51 #define SSL_VALUE_EVENT_HANDLING_MODE_EXPLICIT
52 #define SSL_VALUE_EVENT_HANDLING_MODE_IMPLICIT
53
54 #define SSL_VALUE_STREAM_WRITE_BUF_SIZE
55 #define SSL_VALUE_STREAM_WRITE_BUF_USED
56 #define SSL_VALUE_STREAM_WRITE_BUF_AVAIL
57
58The following convenience macros can also be used:
59
60 int SSL_get_generic_value_uint(SSL *ssl, uint32_t id, uint64_t *value);
61 int SSL_set_generic_value_uint(SSL *ssl, uint32_t id, uint64_t value);
62
63 int SSL_get_feature_request_uint(SSL *ssl, uint32_t id, uint64_t *value);
64 int SSL_set_feature_request_uint(SSL *ssl, uint32_t id, uint64_t value);
65
66 int SSL_get_feature_peer_request_uint(SSL *ssl, uint32_t id, uint64_t *value);
67 int SSL_get_feature_negotiated_uint(SSL *ssl, uint32_t id, uint64_t *value);
68
69 int SSL_get_quic_stream_bidi_local_avail(SSL *ssl, uint64_t *value);
70 int SSL_get_quic_stream_bidi_remote_avail(SSL *ssl, uint64_t *value);
71 int SSL_get_quic_stream_uni_local_avail(SSL *ssl, uint64_t *value);
72 int SSL_get_quic_stream_uni_remote_avail(SSL *ssl, uint64_t *value);
73
74 int SSL_get_event_handling_mode(SSL *ssl, uint64_t *value);
75 int SSL_set_event_handling_mode(SSL *ssl, uint64_t value);
76
77 int SSL_get_stream_write_buf_size(SSL *ssl, uint64_t *value);
78 int SSL_get_stream_write_buf_avail(SSL *ssl, uint64_t *value);
79 int SSL_get_stream_write_buf_used(SSL *ssl, uint64_t *value);
80
81=head1 DESCRIPTION
82
83SSL_get_value_uint() and SSL_set_value_uint() provide access to configurable
84parameters for a given SSL object. Amongst other things, they are used to
85provide control over the feature negotiation process during establishment of a
86connection, and access to statistics about that connection.
87
88SSL_get_value_uint() and SSL_set_value_uint() get and set configurable values
89within a given value class. The value classes are enumerated by
90B<SSL_VALUE_CLASS> and are as follows:
91
92=over 4
93
94=item B<SSL_VALUE_CLASS_GENERIC>
95
96Values in this class do not participate in the feature negotiation process. They
97may represent connection parameters which do not participate in explicit
98negotiation or provide connection statistics. Values in this class might be
99read-write or read-only.
100
101You can access values in this class using the convenience macros
102SSL_get_generic_value_uint() and SSL_set_generic_value_uint() for brevity.
103
104=item B<SSL_VALUE_CLASS_FEATURE_REQUEST>
105
106Values in this class are read-write, and represent what the local party is
107requesting during feature negotiation. Such a request will not necessarily be
108honoured; see B<SSL_VALUE_CLASS_FEATURE_NEGOTIATED>.
109
110A value in this class may become read-only in certain circumstances; for
111example, after a connection has been established, for a value which cannot be
112renegotiated after connection establishment. Setting a value in this class after
113connection establishment represents a request for online renegotiation of the
114specified feature.
115
116You can access values in this class using the convenience macros
117SSL_get_feature_request_uint() and SSL_set_feature_request_uint() for brevity.
118
119=item B<SSL_VALUE_CLASS_FEATURE_PEER_REQUEST>
120
121Values in this value class are read-only, and represent what was requested by a
122peer during feature negotiation. Such a request has not necessarily been
123honoured; see B<SSL_VALUE_CLASS_FEATURE_NEGOTIATED>.
124
125You can access values in this class using the convenience macro
126SSL_get_feature_peer_request_uint() for brevity.
127
128=item B<SSL_VALUE_CLASS_FEATURE_NEGOTIATED>
129
130Values in this value class are read-only, and represent the value which was
131actually negotiated based on both local and peer input during feature
132negotiation. This is the effective value in actual use.
133
134Attempting to read a value in this class will generally fail if the feature
135negotiation process has not yet completed and the value is therefore currently
136unknown, unless the nature of the feature in question causes a provisional value
137to be used prior to completion of feature negotiation, in which case that value
138may be returned. If an online (post-handshake) renegotiation of a feature is
139in progress, retrieving the negotiated value will continue to retrieve the
140previous negotiated value until that process is completed. See the documentation
141of specific values for full details of its behaviour.
142
143You can access values in this class using the convenience macro
144SSL_get_feature_negotiated_uint() for brevity.
145
146=back
147
148=head1 CONFIGURABLE VALUES FOR QUIC OBJECTS
149
150The following configurable values are supported for QUIC SSL objects. Whether a
151value is supported for a QUIC connection SSL object or a QUIC stream SSL object
152is indicated in the heading for each value. Values supported for QUIC stream SSL
153objects are also supported on QUIC connection SSL objects if they have a default
154stream attached.
155
156SSL_get_value() does not cause internal event processing to occur unless the
157documentation for a specific value specifies otherwise.
158
159=over 4
160
161=item B<SSL_VALUE_QUIC_IDLE_TIMEOUT> (connection object)
162
163Negotiated feature value. This configures the desired QUIC idle timeout in
164milliseconds, where 0 represents a lack of an idle timeout. This feature can
165only be configured prior to connection establishment and cannot be subsequently
166changed.
167
168This release of OpenSSL uses a default value of 30 seconds. This default value
169may change between releases of OpenSSL.
170
171=item B<SSL_VALUE_QUIC_STREAM_BIDI_LOCAL_AVAIL> (connection object)
172
173Generic read-only statistical value. The number of bidirectional,
174locally-initiated streams available to be created (but not yet created). For
175example, a value of 100 would mean that L<SSL_new_stream(3)> could be called 100
176times to create 100 bidirectional streams before L<SSL_new_stream(3)> would
177block or fail due to backpressure.
178
179Can be queried using the convenience macro
180SSL_get_quic_stream_bidi_local_avail().
181
182=item B<SSL_VALUE_QUIC_STREAM_UNI_LOCAL_AVAIL> (connection object)
183
184As above, but provides the number of unidirectional, locally-initiated streams
185available to be created (but not yet created).
186
187Can be queried using the convenience macro
188SSL_get_quic_stream_uni_local_avail().
189
190=item B<SSL_VALUE_QUIC_STREAM_BIDI_REMOTE_AVAIL> (connection object)
191
192As above, but provides the number of bidirectional, remotely-initiated streams
193available to be created (but not yet created) by the peer. This represents the
194number of streams the local endpoint has authorised the peer to create in terms
195of QUIC stream creation flow control.
196
197Can be queried using the convenience macro
198SSL_get_quic_stream_bidi_remote_avail().
199
200=item B<SSL_VALUE_QUIC_STREAM_UNI_REMOTE_AVAIL> (connection object)
201
202As above, but provides the number of unidirectional, remotely-initiated streams
203available to be created (but not yet created).
204
205Can be queried using the convenience macro
206SSL_get_quic_stream_uni_remote_avail().
207
208=item B<SSL_VALUE_EVENT_HANDLING_MODE> (connection or stream object)
209
210Generic value. This is an integer value which takes one of the following values,
211and determines the event handling mode in use:
212
213=over 4
214
215=item B<SSL_VALUE_EVENT_HANDLING_MODE_INHERIT>
216
217When set, the event handling mode used is inherited from the value set on the
218parent connection (for a stream), or, for a connection, defaults to the implicit
219event handling model.
220
221When a new connection is created, or a new stream is created or accepted, it
222defaults to this setting.
223
224=item B<SSL_VALUE_EVENT_HANDLING_MODE_IMPLICIT> (Implicit event handling)
225
226If set to this value, the implicit event handling model is used. Under this
227model, QUIC objects will automatically perform background event processing
228(equivalent to a call to L<SSL_handle_events(3)>) when calls to I/O functions
229such as L<SSL_read_ex(3)> or L<SSL_write_ex(3)> are made on a QUIC SSL object.
230This helps to maintain the health of the QUIC connection and ensures that
231incoming datagrams and timeout events are processed.
232
233=item B<SSL_VALUE_EVENT_HANDLING_MODE_EXPLICIT> (Explicit event handling)
234
235If set to this value, the explicit event handling model is used. Under this
236model, B<nonblocking> calls to I/O functions such as L<SSL_read_ex(3)> or
237L<SSL_write_ex(3)> do not result in the automatic processing of QUIC events. Any
238new incoming network traffic is not handled; no new outgoing network traffic is
239generated, and pending timeout events are not processed. This allows an
240application to obtain greater control over the circumstances in which QUIC event
241processing occurs. If this event handling model is used, it is the application's
242responsibility to call L<SSL_handle_events(3)> as and when called for by the
243QUIC implementation; see the L<SSL_get_rpoll_descriptor(3)> man page for more
244information.
245
246Selecting this model does not affect the operation of blocking I/O calls, which
247will continue to use the implicit event handling model. Therefore, applications
248using this model will generally want to disable blocking operation using
249L<SSL_set_blocking_mode(3)>.
250
251=back
252
253Can be configured using the convenience macros SSL_get_event_handling_mode() and
254SSL_set_event_handling_mode().
255
256A call to SSL_set_value_uint() which causes this value to switch back to the
257implicit event handling model does not in itself cause implicit event handling
258to occur; such handling will occur on the next I/O API call. Equally, a call to
259SSL_set_value_uint() which causes this value to switch to the explicit event
260handling model will not cause event handling to occur before making that
261transition.
262
263This value controls whether implicit event handling occurs when making an I/O
264API call on the SSL object it is set on. However, event processing is not
265confined to state which relates to only that object. For example, if you
266configure explicit event handling on QUIC stream SSL object "A" and configure
267implicit event handling on QUIC stream SSL object "B", a call to an I/O function
268on "B" may result in state changes to "A". In other words, if event handling
269does happen as a result of an API call to an object related to a connection,
270processing of background events (for example, received QUIC network traffic) may
271also affect the state of any other object related to a connection.
272
273=item B<SSL_VALUE_STREAM_WRITE_BUF_SIZE> (stream object)
274
275Generic read-only statistical value. The size of the write buffer allocated to
276hold data written to a stream with L<SSL_write_ex(3)> until it is transmitted
277and subsequently acknowledged by the peer. This value may change at any time, as
278buffer sizes are optimised in response to network conditions to optimise
279throughput.
280
281Can be queried using the convenience macro SSL_get_stream_write_buf_size().
282
283=item B<SSL_VALUE_STREAM_WRITE_BUF_USED> (stream object)
284
285Generic read-only statistical value. The number of bytes currently consumed
286in the write buffer which have yet to be acknowledged by the peer. Successful
287calls to L<SSL_write_ex(3)> which accept data cause this number to increase.
288This number will then decrease as data is acknowledged by the peer.
289
290Can be queried using the convenience macro SSL_get_stream_write_buf_used().
291
292=item B<SSL_VALUE_STREAM_WRITE_BUF_AVAIL> (stream object)
293
294Generic read-only statistical value. The number of bytes available in the write
295buffer which have yet to be consumed by calls to L<SSL_write_ex(3)>. Successful
296calls to L<SSL_write_ex(3)> which accept data cause this number to decrease.
297This number will increase as data is acknowledged by the peer. It may also
298change if the buffer is resized automatically to optimise throughput.
299
300Can be queried using the convenience macro SSL_get_stream_write_buf_avail().
301
302=back
303
304No configurable values are currently defined for non-QUIC SSL objects.
305
306=head1 RETURN VALUES
307
308Returns 1 on success or 0 on failure. This function can fail for a number of
309reasons:
310
311=over 4
312
313=item
314
315An argument is invalid (e.g. NULL pointer or invalid class).
316
317=item
318
319The given value is not supported by the SSL object on which it was called.
320
321=item
322
323The given operation (get or set) is not supported by the specified
324configurable value.
325
326=item
327
328You are trying to modify the given value and the value is not modifiable at this
329time.
330
331=back
332
333=head1 SEE ALSO
334
335L<SSL_ctrl(3)>, L<SSL_get_accept_stream_queue_len(3)>,
336L<SSL_get_stream_read_state(3)>, L<SSL_get_stream_write_state(3)>,
337L<SSL_get_stream_read_error_code(3)>, L<SSL_get_stream_write_error_code(3)>,
338L<SSL_set_default_stream_mode(3)>, L<SSL_set_incoming_stream_policy(3)>
339
340=head1 HISTORY
341
342These functions were added in OpenSSL 3.3.
343
344=head1 COPYRIGHT
345
346Copyright 2002-2024 The OpenSSL Project Authors. All Rights Reserved.
347
348Licensed under the Apache License 2.0 (the "License").  You may not use
349this file except in compliance with the License.  You can obtain a copy
350in the file LICENSE in the source distribution or at
351L<https://www.openssl.org/source/license.html>.
352
353=cut
354