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23 .TH CURLINFO_TLS_SSL_PTR 3 "23 Feb 2016" "libcurl 7.48.0" "curl_easy_getinfo options"
25 CURLINFO_TLS_SESSION, CURLINFO_TLS_SSL_PTR \- get TLS session info
28 #include <curl/curl.h>
30 CURLcode curl_easy_getinfo(CURL *handle, CURLINFO_TLS_SSL_PTR,
31 struct curl_tlssessioninfo **session);
33 /* if you need compatibility with libcurl < 7.48.0 use
34 CURLINFO_TLS_SESSION instead: */
36 CURLcode curl_easy_getinfo(CURL *handle, CURLINFO_TLS_SESSION,
37 struct curl_tlssessioninfo **session);
39 Pass a pointer to a 'struct curl_tlssessioninfo *'. The pointer will be
40 initialized to refer to a 'struct curl_tlssessioninfo *' that will contain an
41 enum indicating the SSL library used for the handshake and a pointer to the
42 respective internal TLS session structure of this underlying SSL library.
44 This option may be useful for example to extract certificate information in a
45 format convenient for further processing, such as manual validation. Refer to
46 the \fBLIMITATIONS\fP section.
49 struct curl_tlssessioninfo {
50 curl_sslbackend backend;
55 The \fIbackend\fP struct member is one of the defines in the CURLSSLBACKEND_*
56 series: CURLSSLBACKEND_NONE (when built without TLS support),
57 CURLSSLBACKEND_AXTLS, CURLSSLBACKEND_CYASSL, CURLSSLBACKEND_DARWINSSL,
58 CURLSSLBACKEND_GNUTLS, CURLSSLBACKEND_GSKIT, CURLSSLBACKEND_MBEDTLS,
59 CURLSSLBACKEND_NSS, CURLSSLBACKEND_OPENSSL, CURLSSLBACKEND_POLARSSL or
60 CURLSSLBACKEND_SCHANNEL. (Note that the OpenSSL forks are all reported as just
63 The \fIinternals\fP struct member will point to a TLS library specific pointer
64 for the active ("in use") SSL connection, with the following underlying types:
73 CURLINFO_TLS_SESSION: SSL_CTX *
75 CURLINFO_TLS_SSL_PTR: SSL *
77 Since 7.48.0 the \fIinternals\fP member can point to these other SSL backends
86 .IP "Secure Channel (WinSSL)"
88 .IP "Secure Transport (DarwinSSL)"
90 .IP "WolfSSL (formerly CyaSSL)"
94 If the \fIinternals\fP pointer is NULL then either the SSL backend is not
95 supported, an SSL session has not yet been established or the connection is no
96 longer associated with the easy handle (eg curl_easy_perform has returned).
98 \fBThis option has some limitations that could make it unsafe when it comes to
99 the manual verification of certificates.\fP
101 This option only retrieves the first in-use SSL session pointer for your easy
102 handle, however your easy handle may have more than one in-use SSL session if
103 using FTP over SSL. That is because the FTP protocol has a control channel and
104 a data channel and one or both may be over SSL. \fBCurrently there is no way to
105 retrieve a second in-use SSL session associated with an easy handle.\fP
107 This option has not been thoroughly tested with plaintext protocols that can be
108 upgraded/downgraded to/from SSL: FTP, SMTP, POP3, IMAP when used with
109 \fICURLOPT_USE_SSL(3)\fP. Though you will be able to retrieve the SSL pointer,
110 it's possible that before you can do that \fBdata (including auth) may have
111 already been sent over a connection after it was upgraded.\fP
113 Renegotiation. If unsafe renegotiation or renegotiation in a way that the
114 certificate is allowed to change is allowed by your SSL library this may occur
115 and the certificate may change, and \fBdata may continue to be sent or received
116 after renegotiation but before you are able to get the (possibly) changed SSL
117 pointer,\fP with the (possibly) changed certificate information.
119 If you are using OpenSSL or wolfSSL then \fICURLOPT_SSL_CTX_FUNCTION(3)\fP can
120 be used to set a certificate verification callback in the CTX. That is safer
121 than using this option to poll for certificate changes and doesn't suffer from
122 any of the problems above. There is currently no way in libcurl to set a
123 verification callback for the other SSL backends.
125 How are you using this option? Are you affected by any of these limitations?
126 Please let us know by making a comment at
127 https://github.com/curl/curl/issues/685
135 This option supersedes \fICURLINFO_TLS_SESSION(3)\fP which was added in 7.34.0.
136 This option is exactly the same as that option except in the case of OpenSSL.
138 Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.
140 .BR curl_easy_getinfo "(3), " curl_easy_setopt "(3), "
141 .BR CURLINFO_TLS_SESSION "(3), "