SSL_get_error 3 2005-04-23 0.9.9-dev OpenSSL
NAME
SSL_get_error - obtain result code for TLS/SSL I/O operation
LIBRARY
libcrypto, -lcrypto
SYNOPSIS
#include
int SSL_get_error(const SSL *ssl, int ret);
DESCRIPTION
_S_S_L___g_e_t___e_r_r_o_r_(_) returns a result code (suitable for the C "switch"
statement) for a preceding call to _S_S_L___c_o_n_n_e_c_t_(_), _S_S_L___a_c_c_e_p_t_(_), _S_S_L___d_o___h_a_n_d_s_h_a_k_e_(_),
_S_S_L___r_e_a_d_(_), _S_S_L___p_e_e_k_(_), or _S_S_L___w_r_i_t_e_(_) on ssssll. The value returned by
that TLS/SSL I/O function must be passed to _S_S_L___g_e_t___e_r_r_o_r_(_) in parameter
rreett.
In addition to ssssll and rreett, _S_S_L___g_e_t___e_r_r_o_r_(_) inspects the
current thread's OpenSSL error queue. Thus, _S_S_L___g_e_t___e_r_r_o_r_(_) must be
used in the same thread that performed the TLS/SSL I/O operation, and no
other OpenSSL function calls should appear in between. The current
thread's error queue must be empty before the TLS/SSL I/O operation is
attempted, or _S_S_L___g_e_t___e_r_r_o_r_(_) will not work reliably.
RETURN VALUES
The following return values can currently occur:
-
SSL_ERROR_NONE
The TLS/SSL I/O operation completed. This result code is returned
-
if and only if rreett >> 00.
-
SSL_ERROR_ZERO_RETURN
The TLS/SSL connection has been closed. If the protocol version is SSL 3.0
-
or TLS 1.0, this result code is returned only if a closure
alert has occurred in the protocol, i.e. if the connection has been
closed cleanly. Note that in this case SSSSLL__EERRRROORR__ZZEERROO__RREETTUURRNN
does not necessarily indicate that the underlying transport
has been closed.
-
SSL_ERROR_WANT_READ, SSL_ERROR_WANT_WRITE
The operation did not complete; the same TLS/SSL I/O function should be
-
called again later. If, by then, the underlying BBIIOO has data
available for reading (if the result code is SSSSLL__EERRRROORR__WWAANNTT__RREEAADD)
or allows writing data (SSSSLL__EERRRROORR__WWAANNTT__WWRRIITTEE), then some TLS/SSL
protocol progress will take place, i.e. at least part of an TLS/SSL
record will be read or written. Note that the retry may again lead to
a SSSSLL__EERRRROORR__WWAANNTT__RREEAADD or SSSSLL__EERRRROORR__WWAANNTT__WWRRIITTEE condition.
There is no fixed upper limit for the number of iterations that
may be necessary until progress becomes visible at application
protocol level.
For socket BBIIOOs (e.g. when _S_S_L___s_e_t___f_d_(_) was used), _s_e_l_e_c_t_(_) or
_p_o_l_l_(_) on the underlying socket can be used to find out when the
TLS/SSL I/O function should be retried.
Caveat: Any TLS/SSL I/O function can lead to either of
SSSSLL__EERRRROORR__WWAANNTT__RREEAADD and SSSSLL__EERRRROORR__WWAANNTT__WWRRIITTEE. In particular,
_S_S_L___r_e_a_d_(_) or _S_S_L___p_e_e_k_(_) may want to write data and _S_S_L___w_r_i_t_e_(_) may want
to read data. This is mainly because TLS/SSL handshakes may occur at any
time during the protocol (initiated by either the client or the server);
_S_S_L___r_e_a_d_(_), _S_S_L___p_e_e_k_(_), and _S_S_L___w_r_i_t_e_(_) will handle any pending handshakes.
-
SSL_ERROR_WANT_CONNECT, SSL_ERROR_WANT_ACCEPT
The operation did not complete; the same TLS/SSL I/O function should be
-
called again later. The underlying BIO was not connected yet to the peer
and the call would block in _c_o_n_n_e_c_t_(_)/_a_c_c_e_p_t_(_). The SSL function should be
called again when the connection is established. These messages can only
appear with a _B_I_O___s___c_o_n_n_e_c_t_(_) or _B_I_O___s___a_c_c_e_p_t_(_) BIO, respectively.
In order to find out, when the connection has been successfully established,
on many platforms _s_e_l_e_c_t_(_) or _p_o_l_l_(_) for writing on the socket file descriptor
can be used.
-
SSL_ERROR_WANT_X509_LOOKUP
The operation did not complete because an application callback set by
-
_S_S_L___C_T_X___s_e_t___c_l_i_e_n_t___c_e_r_t___c_b_(_) has asked to be called again.
The TLS/SSL I/O function should be called again later.
Details depend on the application.
-
SSL_ERROR_SYSCALL
Some I/O error occurred. The OpenSSL error queue may contain more
-
information on the error. If the error queue is empty
(i.e. _E_R_R___g_e_t___e_r_r_o_r_(_) returns 0), rreett can be used to find out more
about the error: If rreett ==== 00, an EOF was observed that violates
the protocol. If rreett ==== --11, the underlying BBIIOO reported an
I/O error (for socket I/O on Unix systems, consult eerrrrnnoo for details).
-
SSL_ERROR_SSL
A failure in the SSL library occurred, usually a protocol error. The
-
OpenSSL error queue contains more information on the error.
SEE ALSO
_s_s_l(3), _o_p_e_n_s_s_l___e_r_r(3)
HISTORY
_S_S_L___g_e_t___e_r_r_o_r_(_) was added in SSLeay 0.8.