SSL_do_handshake(3)
- NetBSD Manual Pages
SSL_do_handshake(3) OpenSSL SSL_do_handshake(3)
NAME
SSL_do_handshake - perform a TLS/SSL handshake
LIBRARY
libcrypto, -lcrypto
SYNOPSIS
#include <openssl/ssl.h>
int SSL_do_handshake(SSL *ssl);
DESCRIPTION
SSL_do_handshake() will wait for a SSL/TLS handshake to
take place. If the connection is in client mode, the hand-
shake will be started. The handshake routines may have to
be explicitly set in advance using either SSL_set_connect_state(3)
or SSL_set_accept_state(3).
NOTES
The behaviour of SSL_do_handshake() depends on the under-
lying BIO.
If the underlying BIO is blocking, SSL_do_handshake() will
only return once the handshake has been finished or an
error occurred, except for SGC (Server Gated Cryptogra-
phy). For SGC, SSL_do_handshake() may return with -1, but
SSL_get_error() will yield SSL_ERROR_WANT_READ/WRITE and
SSL_do_handshake() should be called again.
If the underlying BIO is non-blocking, SSL_do_handshake()
will also return when the underlying BIO could not satisfy
the needs of SSL_do_handshake() to continue the handshake.
In this case a call to SSL_get_error() with the return
value of SSL_do_handshake() 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_do_handshake(). The action depends on
the underlying BIO. When using a non-blocking socket,
nothing is to be done, but select() 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:
1 The TLS/SSL handshake was successfully completed, a
TLS/SSL connection has been established.
0 The TLS/SSL handshake was not successful but was shut
down controlled and by the specifications of the
TLS/SSL protocol. Call SSL_get_error() with the return
value ret to find out the reason.
2002-08-05 0.9.6g 1
SSL_do_handshake(3) OpenSSL SSL_do_handshake(3)
<0 The TLS/SSL handshake was not successful because a
fatal error occurred either at the protocol level or a
connection failure occurred. The shutdown was not
clean. It can also occur of action is need to continue
the operation for non-blocking BIOs. Call
SSL_get_error() with the return value ret to find out
the reason.
SEE ALSO
SSL_get_error(3), SSL_connect(3), SSL_accept(3), ssl(3),
openssl_bio(3), SSL_set_connect_state(3)
2002-08-05 0.9.6g 2
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