/usr/man/cat.3/SSL_get_mode.3
SSL_CTX_set_mode(3) OpenSSL SSL_CTX_set_mode(3)
NAME
SSL_CTX_set_mode, SSL_set_mode, SSL_CTX_get_mode,
SSL_get_mode - manipulate SSL engine mode
SYNOPSIS
#include <openssl/ssl.h>
long SSL_CTX_set_mode(SSL_CTX *ctx, long mode);
long SSL_set_mode(SSL *ssl, long mode);
long SSL_CTX_get_mode(SSL_CTX *ctx);
long SSL_get_mode(SSL *ssl);
DESCRIPTION
SSL_CTX_set_mode() adds the mode set via bitmask in mode to
ctx. Options already set before are not cleared.
SSL_set_mode() adds the mode set via bitmask in mode to ssl.
Options already set before are not cleared.
SSL_CTX_get_mode() returns the mode set for ctx.
SSL_get_mode() returns the mode set for ssl.
NOTES
The following mode changes are available:
SSL_MODE_ENABLE_PARTIAL_WRITE
Allow SSL_write(..., n) to return r with 0 < r < n (i.e.
report success when just a single record has been
written). When not set (the default), SSL_write() will
only report success once the complete chunk was written.
Once SSL_write() returns with r, r bytes have been
successfully written and the next call to SSL_write()
must only send the n-r bytes left, imitating the
behaviour of write().
SSL_MODE_ACCEPT_MOVING_WRITE_BUFFER
Make it possible to retry SSL_write() with changed
buffer location (the buffer contents must stay the
same). This is not the default to avoid the
misconception that non-blocking SSL_write() behaves like
non-blocking write().
SSL_MODE_AUTO_RETRY
Never bother the application with retries if the
transport is blocking. If a renegotiation take place
during normal operation, a SSL_read(3) or SSL_write(3)
would return with -1 and indicate the need to retry with
SSL_ERROR_WANT_READ. In a non-blocking environment
applications must be prepared to handle incomplete
read/write operations. In a blocking environment,
1.0.2t Last change: 2019-09-10 1
SSL_CTX_set_mode(3) OpenSSL SSL_CTX_set_mode(3)
applications are not always prepared to deal with
read/write operations returning without success report.
The flag SSL_MODE_AUTO_RETRY will cause read/write
operations to only return after the handshake and
successful completion.
SSL_MODE_RELEASE_BUFFERS
When we no longer need a read buffer or a write buffer
for a given SSL, then release the memory we were using
to hold it. Released memory is either appended to a
list of unused RAM chunks on the SSL_CTX, or simply
freed if the list of unused chunks would become longer
than SSL_CTX->freelist_max_len, which defaults to 32.
Using this flag can save around 34k per idle SSL
connection. This flag has no effect on SSL v2
connections, or on DTLS connections.
SSL_MODE_SEND_FALLBACK_SCSV
Send TLS_FALLBACK_SCSV in the ClientHello. To be set
only by applications that reconnect with a downgraded
protocol version; see draft-ietf-tls-downgrade-scsv-00
for details.
DO NOT ENABLE THIS if your application attempts a normal
handshake. Only use this in explicit fallback retries,
following the guidance in
draft-ietf-tls-downgrade-scsv-00.
RETURN VALUES
SSL_CTX_set_mode() and SSL_set_mode() return the new mode
bitmask after adding mode.
SSL_CTX_get_mode() and SSL_get_mode() return the current
bitmask.
SEE ALSO
ssl(3), SSL_read(3), SSL_write(3)
HISTORY
SSL_MODE_AUTO_RETRY as been added in OpenSSL 0.9.6.
1.0.2t Last change: 2019-09-10 2
See also SSL_CTX_get_mode(3)
See also SSL_CTX_set_mode(3)
See also SSL_set_mode(3)
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