SSL_CTX_set_mode(3) OpenSSL SSL_CTX_set_mode(3) NNAAMMEE SSL_CTX_set_mode, SSL_set_mode, SSL_CTX_get_mode, SSL_get_mode - manip- ulate SSL engine mode SSYYNNOOPPSSIISS #include 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); DDEESSCCRRIIPPTTIIOONN _S_S_L___C_T_X___s_e_t___m_o_d_e_(_) adds the mode set via bitmask in mmooddee to ccttxx. Options already set before are not cleared. _S_S_L___s_e_t___m_o_d_e_(_) adds the mode set via bitmask in mmooddee to ssssll. Options already set before are not cleared. _S_S_L___C_T_X___g_e_t___m_o_d_e_(_) returns the mode set for ccttxx. _S_S_L___g_e_t___m_o_d_e_(_) returns the mode set for ssssll. NNOOTTEESS 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), _S_S_L___w_r_i_t_e_(_) will only report success once the com- plete chunk was written. Once _S_S_L___w_r_i_t_e_(_) returns with r, r bytes have been successfully written and the next call to _S_S_L___w_r_i_t_e_(_) must only send the n-r bytes left, imitating the behaviour of _w_r_i_t_e_(_). SSL_MODE_ACCEPT_MOVING_WRITE_BUFFER Make it possible to retry _S_S_L___w_r_i_t_e_(_) with changed buffer location (the buffer contents must stay the same). This is not the default to avoid the misconception that non-blocking _S_S_L___w_r_i_t_e_(_) behaves like non-blocking _w_r_i_t_e_(_). SSL_MODE_AUTO_RETRY Never bother the application with retries if the transport is blocking. If a renegotiation take place during normal operation, a _S_S_L___r_e_a_d(3) or _S_S_L___w_r_i_t_e(3) would return with -1 and indicate the need to retry with SSL_ERROR_WANT_READ. In a non-blocking environ- ment 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 suc- cess report. The flag SSL_MODE_AUTO_RETRY will cause read/write operations to only return after the handshake and successful com- pletion. 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. RREETTUURRNN VVAALLUUEESS _S_S_L___C_T_X___s_e_t___m_o_d_e_(_) and _S_S_L___s_e_t___m_o_d_e_(_) return the new mode bitmask after adding mmooddee. _S_S_L___C_T_X___g_e_t___m_o_d_e_(_) and _S_S_L___g_e_t___m_o_d_e_(_) return the current bitmask. SSEEEE AALLSSOO _s_s_l(3), _S_S_L___r_e_a_d(3), _S_S_L___w_r_i_t_e(3) HHIISSTTOORRYY SSL_MODE_AUTO_RETRY as been added in OpenSSL 0.9.6. 1.0.1u 2016-09-22 SSL_CTX_set_mode(3)