SSL_CONNECT(3) BSD Library Functions Manual SSL_CONNECT(3)NAMESSL_connect — initiate the TLS/SSL handshake with a TLS/SSL server
SYNOPSIS
#include <openssl/ssl.h>
int
SSL_connect(SSL *ssl);
DESCRIPTIONSSL_connect() initiates the TLS/SSL handshake with a server. The commu‐
nication channel must already have been set and assigned to the ssl by
setting an underlying BIO.
NOTES
The behaviour of SSL_connect() depends on the underlying BIO.
If the underlying BIO is blocking, SSL_connect() will only return once
the handshake has been finished or an error occurred.
If the underlying BIO is non-blocking, SSL_connect() will also return
when the underlying BIO could not satisfy the needs of SSL_connect() to
continue the handshake, indicating the problem with the return value −1.
In this case a call to SSL_get_error(3) with the return value of
SSL_connect() will yield SSL_ERROR_WANT_READ or SSL_ERROR_WANT_WRITE.
The calling process then must repeat the call after taking appropriate
action to satisfy the needs of SSL_connect(). The action depends on the
underlying BIO. When using a non-blocking socket, nothing is to be done,
but select(2) can be used to check for the required condition. When
using a buffering BIO, like a BIO pair, data must be written into or
retrieved out of the BIO before being able to continue.
RETURN VALUES
The following return values can occur:
0 The TLS/SSL handshake was not successful but was shut down con‐
trolled and by the specifications of the TLS/SSL protocol. Call
SSL_get_error(3) with the return value ret to find out the rea‐
son.
1 The TLS/SSL handshake was successfully completed, and a TLS/SSL
connection has been established.
<0 The TLS/SSL handshake was not successful, because either a fatal
error occurred at the protocol level or a connection failure
occurred. The shutdown was not clean. It can also occur if
action is needed to continue the operation for non-blocking BIOs.
Call SSL_get_error(3) with the return value ret to find out the
reason.
SEE ALSObio(3), ssl(3), SSL_accept(3), SSL_CTX_new(3), SSL_do_handshake(3),
SSL_get_error(3), SSL_set_connect_state(3), SSL_shutdown(3)BSD April 20, 2024 BSD
