5 SSL_CTX_set_mode, SSL_set_mode, SSL_CTX_get_mode, SSL_get_mode - manipulate SSL engine mode
9 #include <openssl/ssl.h>
11 long SSL_CTX_set_mode(SSL_CTX *ctx, long mode);
12 long SSL_set_mode(SSL *ssl, long mode);
14 long SSL_CTX_get_mode(SSL_CTX *ctx);
15 long SSL_get_mode(SSL *ssl);
19 SSL_CTX_set_mode() adds the mode set via bitmask in B<mode> to B<ctx>.
20 Options already set before are not cleared.
22 SSL_set_mode() adds the mode set via bitmask in B<mode> to B<ssl>.
23 Options already set before are not cleared.
25 SSL_CTX_get_mode() returns the mode set for B<ctx>.
27 SSL_get_mode() returns the mode set for B<ssl>.
31 The following mode changes are available:
35 =item SSL_MODE_ENABLE_PARTIAL_WRITE
37 Allow SSL_write_ex(..., n, &r) to return with 0 < r < n (i.e. report success
38 when just a single record has been written). This works in a similar way for
39 SSL_write(). When not set (the default), SSL_write_ex() or SSL_write() will only
40 report success once the complete chunk was written. Once SSL_write_ex() or
41 SSL_write() returns successful, B<r> bytes have been written and the next call
42 to SSL_write_ex() or SSL_write() must only send the n-r bytes left, imitating
43 the behaviour of write().
45 =item SSL_MODE_ACCEPT_MOVING_WRITE_BUFFER
47 Make it possible to retry SSL_write_ex() or SSL_write() with changed buffer
48 location (the buffer contents must stay the same). This is not the default to
49 avoid the misconception that non-blocking SSL_write() behaves like
52 =item SSL_MODE_AUTO_RETRY
54 Never bother the application with retries if the transport is blocking.
55 If a renegotiation take place during normal operation, a
56 L<SSL_read_ex(3)>, L<SSL_read(3)>, L<SSL_write_ex(3)> or L<SSL_write(3)> would
57 return with a failure and indicate the need to retry with SSL_ERROR_WANT_READ.
58 In a non-blocking environment applications must be prepared to handle
59 incomplete read/write operations.
60 In a blocking environment, applications are not always prepared to
61 deal with read/write operations returning without success report. The
62 flag SSL_MODE_AUTO_RETRY will cause read/write operations to only
63 return after the handshake and successful completion.
65 =item SSL_MODE_RELEASE_BUFFERS
67 When we no longer need a read buffer or a write buffer for a given SSL,
68 then release the memory we were using to hold it.
70 save around 34k per idle SSL connection.
71 This flag has no effect on SSL v2 connections, or on DTLS connections.
73 =item SSL_MODE_SEND_FALLBACK_SCSV
75 Send TLS_FALLBACK_SCSV in the ClientHello.
76 To be set only by applications that reconnect with a downgraded protocol
77 version; see draft-ietf-tls-downgrade-scsv-00 for details.
79 DO NOT ENABLE THIS if your application attempts a normal handshake.
80 Only use this in explicit fallback retries, following the guidance
81 in draft-ietf-tls-downgrade-scsv-00.
85 Enable asynchronous processing. TLS I/O operations may indicate a retry with
86 SSL_ERROR_WANT_ASYNC with this mode set if an asynchronous capable engine is
87 used to perform cryptographic operations. See L<SSL_get_error(3)>.
93 SSL_CTX_set_mode() and SSL_set_mode() return the new mode bitmask
96 SSL_CTX_get_mode() and SSL_get_mode() return the current bitmask.
100 L<ssl(7)>, L<SSL_read_ex(3)>, L<SSL_read(3)>, L<SSL_write_ex(3)> or
101 L<SSL_write(3)>, L<SSL_get_error(3)>
105 SSL_MODE_ASYNC was first added to OpenSSL 1.1.0.
109 Copyright 2001-2016 The OpenSSL Project Authors. All Rights Reserved.
111 Licensed under the OpenSSL license (the "License"). You may not use
112 this file except in compliance with the License. You can obtain a copy
113 in the file LICENSE in the source distribution or at
114 L<https://www.openssl.org/source/license.html>.