SSL_CTX_set_mode, SSL_set_mode, SSL_CTX_get_mode, SSL_get_mode - manipulate
SSL engine mode
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);
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.
The following mode changes are available:
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
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
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
behaves like non-blocking
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, 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
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.
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
SSL_set_mode() return the
new mode bitmask after adding mode.
SSL_get_mode() return the
ssl(3), SSL_read(3), SSL_write(3)
SSL_MODE_AUTO_RETRY as been added in OpenSSL 0.9.6.
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