1SSL_get_error(3) OpenSSL SSL_get_error(3)
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6 SSL_get_error - obtain result code for TLS/SSL I/O operation
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9 #include <openssl/ssl.h>
10 int SSL_get_error(const SSL *ssl, int ret);
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14 SSL_get_error() returns a result code (suitable for the C "switch"
15 statement) for a preceding call to SSL_connect(), SSL_accept(),
16 SSL_do_handshake(), SSL_read(), SSL_peek(), or SSL_write() on ssl. The
17 value returned by that TLS/SSL I/O function must be passed to
18 SSL_get_error() in parameter ret.
19 In addition to ssl and ret, SSL_get_error() inspects the current
21 thread's OpenSSL error queue. Thus, SSL_get_error() must be used in
22 the same thread that performed the TLS/SSL I/O operation, and no other
23 OpenSSL function calls should appear in between. The current thread's
24 error queue must be empty before the TLS/SSL I/O operation is
25 attempted, or SSL_get_error() will not work reliably.
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28 The following return values can currently occur:
29 SSL_ERROR_NONE
31 The TLS/SSL I/O operation completed. This result code is returned
32 if and only if ret > 0.
33 SSL_ERROR_ZERO_RETURN
35 The TLS/SSL connection has been closed. If the protocol version is
36 SSL 3.0 or higher, this result code is returned only if a closure
37 alert has occurred in the protocol, i.e. if the connection has been
38 closed cleanly. Note that in this case SSL_ERROR_ZERO_RETURN does
39 not necessarily indicate that the underlying transport has been
40 closed.
41 SSL_ERROR_WANT_READ, SSL_ERROR_WANT_WRITE
43 The operation did not complete; the same TLS/SSL I/O function
44 should be called again later. If, by then, the underlying BIO has
45 data available for reading (if the result code is
46 SSL_ERROR_WANT_READ) or allows writing data (SSL_ERROR_WANT_WRITE),
47 then some TLS/SSL protocol progress will take place, i.e. at least
48 part of an TLS/SSL record will be read or written. Note that the
49 retry may again lead to a SSL_ERROR_WANT_READ or
50 SSL_ERROR_WANT_WRITE condition. There is no fixed upper limit for
51 the number of iterations that may be necessary until progress
52 becomes visible at application protocol level.
53 For socket BIOs (e.g. when SSL_set_fd() was used), select() or
55 poll() on the underlying socket can be used to find out when the
56 TLS/SSL I/O function should be retried.
57 Caveat: Any TLS/SSL I/O function can lead to either of
59 SSL_ERROR_WANT_READ and SSL_ERROR_WANT_WRITE. In particular,
60 SSL_read() or SSL_peek() may want to write data and SSL_write() may
61 want to read data. This is mainly because TLS/SSL handshakes may
62 occur at any time during the protocol (initiated by either the
63 client or the server); SSL_read(), SSL_peek(), and SSL_write() will
64 handle any pending handshakes.
65 SSL_ERROR_WANT_CONNECT, SSL_ERROR_WANT_ACCEPT
67 The operation did not complete; the same TLS/SSL I/O function
68 should be called again later. The underlying BIO was not connected
69 yet to the peer and the call would block in connect()/accept(). The
70 SSL function should be called again when the connection is
71 established. These messages can only appear with a BIO_s_connect()
72 or BIO_s_accept() BIO, respectively. In order to find out, when
73 the connection has been successfully established, on many platforms
74 select() or poll() for writing on the socket file descriptor can be
75 used.
76 SSL_ERROR_WANT_X509_LOOKUP
78 The operation did not complete because an application callback set
79 by SSL_CTX_set_client_cert_cb() has asked to be called again. The
80 TLS/SSL I/O function should be called again later. Details depend
81 on the application.
82 SSL_ERROR_SYSCALL
84 Some non-recoverable I/O error occurred. The OpenSSL error queue
85 may contain more information on the error. For socket I/O on Unix
86 systems, consult errno for details.
87 SSL_ERROR_SSL
89 A failure in the SSL library occurred, usually a protocol error.
90 The OpenSSL error queue contains more information on the error.
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93 ssl(3), err(3)
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96 SSL_get_error() was added in SSLeay 0.8.
971.0.2o 2020-08-01 SSL_get_error(3)