SSL_clear.3ossl 4.3 KB

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  57. .IX Title "SSL_CLEAR 3ossl"
  58. .TH SSL_CLEAR 3ossl 2025-01-17 3.4.0 OpenSSL
  59. .\" For nroff, turn off justification. Always turn off hyphenation; it makes
  60. .\" way too many mistakes in technical documents.
  61. .if n .ad l
  62. .nh
  63. .SH NAME
  64. SSL_clear \- reset SSL object to allow another connection
  65. .SH SYNOPSIS
  66. .IX Header "SYNOPSIS"
  67. .Vb 1
  68. \& #include <openssl/ssl.h>
  69. \&
  70. \& int SSL_clear(SSL *ssl);
  71. .Ve
  72. .SH DESCRIPTION
  73. .IX Header "DESCRIPTION"
  74. Reset \fBssl\fR to allow another connection. All settings (method, ciphers,
  75. BIOs) are kept.
  76. .SH NOTES
  77. .IX Header "NOTES"
  78. SSL_clear is used to prepare an SSL object for a new connection. While all
  79. settings are kept, a side effect is the handling of the current SSL session.
  80. If a session is still \fBopen\fR, it is considered bad and will be removed
  81. from the session cache, as required by RFC2246. A session is considered open,
  82. if \fBSSL_shutdown\fR\|(3) was not called for the connection
  83. or at least \fBSSL_set_shutdown\fR\|(3) was used to
  84. set the SSL_SENT_SHUTDOWN state.
  85. .PP
  86. If a session was closed cleanly, the session object will be kept and all
  87. settings corresponding. This explicitly means, that e.g. the special method
  88. used during the session will be kept for the next handshake. So if the
  89. session was a TLSv1 session, a SSL client object will use a TLSv1 client
  90. method for the next handshake and a SSL server object will use a TLSv1
  91. server method, even if TLS_*_methods were chosen on startup. This
  92. will might lead to connection failures (see \fBSSL_new\fR\|(3))
  93. for a description of the method's properties.
  94. .PP
  95. This function is not supported on QUIC SSL objects and returns failure if called
  96. on such an object.
  97. .SH WARNINGS
  98. .IX Header "WARNINGS"
  99. \&\fBSSL_clear()\fR resets the SSL object to allow for another connection. The
  100. reset operation however keeps several settings of the last sessions
  101. (some of these settings were made automatically during the last
  102. handshake). It only makes sense for a new connection with the exact
  103. same peer that shares these settings, and may fail if that peer
  104. changes its settings between connections. Use the sequence
  105. \&\fBSSL_get_session\fR\|(3);
  106. \&\fBSSL_new\fR\|(3);
  107. \&\fBSSL_set_session\fR\|(3);
  108. \&\fBSSL_free\fR\|(3)
  109. instead to avoid such failures
  110. (or simply \fBSSL_free\fR\|(3); \fBSSL_new\fR\|(3)
  111. if session reuse is not desired).
  112. .SH "RETURN VALUES"
  113. .IX Header "RETURN VALUES"
  114. The following return values can occur:
  115. .IP 0 4
  116. The \fBSSL_clear()\fR operation could not be performed. Check the error stack to
  117. find out the reason.
  118. .IP 1 4
  119. .IX Item "1"
  120. The \fBSSL_clear()\fR operation was successful.
  121. .PP
  122. \&\fBSSL_new\fR\|(3), \fBSSL_free\fR\|(3),
  123. \&\fBSSL_shutdown\fR\|(3), \fBSSL_set_shutdown\fR\|(3),
  124. \&\fBSSL_CTX_set_options\fR\|(3), \fBssl\fR\|(7),
  125. \&\fBSSL_CTX_set_client_cert_cb\fR\|(3)
  126. .SH COPYRIGHT
  127. .IX Header "COPYRIGHT"
  128. Copyright 2000\-2023 The OpenSSL Project Authors. All Rights Reserved.
  129. .PP
  130. Licensed under the Apache License 2.0 (the "License"). You may not use
  131. this file except in compliance with the License. You can obtain a copy
  132. in the file LICENSE in the source distribution or at
  133. <https://www.openssl.org/source/license.html>.