1SSL_GET_ERROR(3ossl) OpenSSL SSL_GET_ERROR(3ossl)
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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_ex(), SSL_read(), SSL_peek_ex(),
17 SSL_peek(), SSL_shutdown(), SSL_write_ex() or SSL_write() on ssl. The
18 value returned by that TLS/SSL I/O function must be passed to
19 SSL_get_error() in parameter ret.
20 In addition to ssl and ret, SSL_get_error() inspects the current
22 thread's OpenSSL error queue. Thus, SSL_get_error() must be used in
23 the same thread that performed the TLS/SSL I/O operation, and no other
24 OpenSSL function calls should appear in between. The current thread's
25 error queue must be empty before the TLS/SSL I/O operation is
26 attempted, or SSL_get_error() will not work reliably.
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29 Some TLS implementations do not send a close_notify alert on shutdown.
30 On an unexpected EOF, versions before OpenSSL 3.0 returned
32 SSL_ERROR_SYSCALL, nothing was added to the error stack, and errno was
33 0. Since OpenSSL 3.0 the returned error is SSL_ERROR_SSL with a
34 meaningful error on the error stack.
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37 The following return values can currently occur:
38 SSL_ERROR_NONE
40 The TLS/SSL I/O operation completed. This result code is returned
41 if and only if ret > 0.
42 SSL_ERROR_ZERO_RETURN
44 The TLS/SSL peer has closed the connection for writing by sending
45 the close_notify alert. No more data can be read. Note that
46 SSL_ERROR_ZERO_RETURN does not necessarily indicate that the
47 underlying transport has been closed.
48 This error can also appear when the option
50 SSL_OP_IGNORE_UNEXPECTED_EOF is set. See SSL_CTX_set_options(3) for
51 more details.
52 SSL_ERROR_WANT_READ, SSL_ERROR_WANT_WRITE
54 The operation did not complete and can be retried later.
55 SSL_ERROR_WANT_READ is returned when the last operation was a read
57 operation from a nonblocking BIO. It means that not enough data
58 was available at this time to complete the operation. If at a
59 later time the underlying BIO has data available for reading the
60 same function can be called again.
61 SSL_read() and SSL_read_ex() can also set SSL_ERROR_WANT_READ when
63 there is still unprocessed data available at either the SSL or the
64 BIO layer, even for a blocking BIO. See SSL_read(3) for more
65 information.
66 SSL_ERROR_WANT_WRITE is returned when the last operation was a
68 write to a nonblocking BIO and it was unable to sent all data to
69 the BIO. When the BIO is writable again, the same function can be
70 called again.
71 Note that the retry may again lead to an SSL_ERROR_WANT_READ or
73 SSL_ERROR_WANT_WRITE condition. There is no fixed upper limit for
74 the number of iterations that may be necessary until progress
75 becomes visible at application protocol level.
76 It is safe to call SSL_read() or SSL_read_ex() when more data is
78 available even when the call that set this error was an SSL_write()
79 or SSL_write_ex(). However, if the call was an SSL_write() or
80 SSL_write_ex(), it should be called again to continue sending the
81 application data. If you get SSL_ERROR_WANT_WRITE from SSL_write()
82 or SSL_write_ex() then you should not do any other operation that
83 could trigger IO other than to repeat the previous SSL_write()
84 call.
85 For socket BIOs (e.g. when SSL_set_fd() was used), select() or
87 poll() on the underlying socket can be used to find out when the
88 TLS/SSL I/O function should be retried.
89 Caveat: Any TLS/SSL I/O function can lead to either of
91 SSL_ERROR_WANT_READ and SSL_ERROR_WANT_WRITE. In particular,
92 SSL_read_ex(), SSL_read(), SSL_peek_ex(), or SSL_peek() may want to
93 write data and SSL_write() or SSL_write_ex() may want to read data.
94 This is mainly because TLS/SSL handshakes may occur at any time
95 during the protocol (initiated by either the client or the server);
96 SSL_read_ex(), SSL_read(), SSL_peek_ex(), SSL_peek(),
97 SSL_write_ex(), and SSL_write() will handle any pending handshakes.
98 SSL_ERROR_WANT_CONNECT, SSL_ERROR_WANT_ACCEPT
100 The operation did not complete; the same TLS/SSL I/O function
101 should be called again later. The underlying BIO was not connected
102 yet to the peer and the call would block in connect()/accept(). The
103 SSL function should be called again when the connection is
104 established. These messages can only appear with a BIO_s_connect()
105 or BIO_s_accept() BIO, respectively. In order to find out, when
106 the connection has been successfully established, on many platforms
107 select() or poll() for writing on the socket file descriptor can be
108 used.
109 SSL_ERROR_WANT_X509_LOOKUP
111 The operation did not complete because an application callback set
112 by SSL_CTX_set_client_cert_cb() has asked to be called again. The
113 TLS/SSL I/O function should be called again later. Details depend
114 on the application.
115 SSL_ERROR_WANT_ASYNC
117 The operation did not complete because an asynchronous engine is
118 still processing data. This will only occur if the mode has been
119 set to SSL_MODE_ASYNC using SSL_CTX_set_mode(3) or SSL_set_mode(3)
120 and an asynchronous capable engine is being used. An application
121 can determine whether the engine has completed its processing using
122 select() or poll() on the asynchronous wait file descriptor. This
123 file descriptor is available by calling SSL_get_all_async_fds(3) or
124 SSL_get_changed_async_fds(3). The TLS/SSL I/O function should be
125 called again later. The function must be called from the same
126 thread that the original call was made from.
127 SSL_ERROR_WANT_ASYNC_JOB
129 The asynchronous job could not be started because there were no
130 async jobs available in the pool (see ASYNC_init_thread(3)). This
131 will only occur if the mode has been set to SSL_MODE_ASYNC using
132 SSL_CTX_set_mode(3) or SSL_set_mode(3) and a maximum limit has been
133 set on the async job pool through a call to ASYNC_init_thread(3).
134 The application should retry the operation after a currently
135 executing asynchronous operation for the current thread has
136 completed.
137 SSL_ERROR_WANT_CLIENT_HELLO_CB
139 The operation did not complete because an application callback set
140 by SSL_CTX_set_client_hello_cb() has asked to be called again. The
141 TLS/SSL I/O function should be called again later. Details depend
142 on the application.
143 SSL_ERROR_SYSCALL
145 Some non-recoverable, fatal I/O error occurred. The OpenSSL error
146 queue may contain more information on the error. For socket I/O on
147 Unix systems, consult errno for details. If this error occurs then
148 no further I/O operations should be performed on the connection and
149 SSL_shutdown() must not be called.
150 This value can also be returned for other errors, check the error
152 queue for details.
153 SSL_ERROR_SSL
155 A non-recoverable, fatal error in the SSL library occurred, usually
156 a protocol error. The OpenSSL error queue contains more
157 information on the error. If this error occurs then no further I/O
158 operations should be performed on the connection and SSL_shutdown()
159 must not be called.
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162 ssl(7)
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165 The SSL_ERROR_WANT_ASYNC error code was added in OpenSSL 1.1.0. The
166 SSL_ERROR_WANT_CLIENT_HELLO_CB error code was added in OpenSSL 1.1.1.
167
169 Copyright 2000-2021 The OpenSSL Project Authors. All Rights Reserved.
170 Licensed under the Apache License 2.0 (the "License"). You may not use
172 this file except in compliance with the License. You can obtain a copy
173 in the file LICENSE in the source distribution or at
174 <https://www.openssl.org/source/license.html>.
1753.0.9 2023-07-27 SSL_GET_ERROR(3ossl)