<p class="level0">Pass a pointer to your callback function, which should match the prototype shown above.
<p class="level0">This callback function gets called by libcurl just before the initialization of an SSL connection after having processed all other SSL related options to give a last chance to an application to modify the behaviour of the SSL initialization. The <span Class="emphasis">ssl_ctx</span> parameter is actually a pointer to the SSL library's <span Class="emphasis">SSL_CTX</span>. If an error is returned from the callback no attempt to establish a connection is made and the perform operation will return the callback's error code. Set the <span Class="emphasis">userptr</span> argument with the <a Class="emphasis" href="./CURLOPT_SSL_CTX_DATA.html">CURLOPT_SSL_CTX_DATA</a> option.
<p class="level0">This function will get called on all new connections made to a server, during the SSL negotiation. The SSL_CTX pointer will be a new one every time.
-<p class="level0">To use this properly, a non-trivial amount of knowledge of your SSL library is necessary. For example, you can use this function to call library-specific callbacks to add additional validation code for certificates, and even to change the actual URI of a HTTPS request
(example used in the lib509 test case). See also the example section for a replacement of the key, certificate and trust file settings. <a name="DEFAULT"></a><h2 class="nroffsh">DEFAULT</h2>
+<p class="level0">To use this properly, a non-trivial amount of knowledge of your SSL library is necessary. For example, you can use this function to call library-specific callbacks to add additional validation code for certificates, and even to change the actual URI of a HTTPS request. <a name="DEFAULT"></a><h2 class="nroffsh">DEFAULT</h2>
<p class="level0">NULL <a name="PROTOCOLS"></a><h2 class="nroffsh">PROTOCOLS</h2>
-<p class="level0">All TLS based protocols: HTTPS, FTPS, IMAPS, POP3, SMTPS etc. <a name="EXAMPLE"></a><h2 class="nroffsh">EXAMPLE</h2>
-<p class="level0">TODO <a name="AVAILABILITY"></a><h2 class="nroffsh">AVAILABILITY</h2>
+<p class="level0">All TLS based protocols: HTTPS, FTPS, IMAPS, POP3S, SMTPS etc. <a name="EXAMPLE"></a><h2 class="nroffsh">EXAMPLE</h2>
+<p class="level0"><pre class="level0">
+/* OpenSSL specific */
+
+#include <openssl/ssl.h>
+#include <curl/curl.h>
+#include <stdio.h>
+
+static CURLcode sslctx_function(CURL *curl, void *sslctx, void *parm)
+{
+ X509_STORE *store;
+ X509 *cert=NULL;
+ BIO *bio;
+ char *mypem = /* example CA cert PEM - shortened */
+ "-----BEGIN CERTIFICATE-----n"
+ "MIIHPTCCBSWgAwIBAgIBADANBgkqhkiG9w0BAQQFADB5MRAwDgYDVQQKEwdSb290n"
+ "IENBMR4wHAYDVQQLExVodHRwOi8vd3d3LmNhY2VydC5vcmcxIjAgBgNVBAMTGUNBn"
+ "IENlcnQgU2lnbmluZyBBdXRob3JpdHkxITAfBgkqhkiG9w0BCQEWEnN1cHBvcnRAn"
+ "Y2FjZXJ0Lm9yZzAeFw0wMzAzMzAxMjI5NDlaFw0zMzAzMjkxMjI5NDlaMHkxEDAOn"
+ "GCSNe9FINSkYQKyTYOGWhlC0elnYjyELn8+CkcY7v2vcB5G5l1YjqrZslMZIBjzkn"
+ "zk6q5PYvCdxTby78dOs6Y5nCpqyJvKeyRKANihDjbPIky/qbn3BHLt4Ui9SyIAmWn"
+ "omTxJBzcoTWcFbLUvFUufQb1nA5V9FrWk9p2rSVzTMVDn"\
+ "-----END CERTIFICATE-----n";
+ /* get a BIO */
+ bio=BIO_new_mem_buf(mypem, -1);
+ /* use it to read the PEM formatted certificate from memory into an X509
+ * structure that SSL can use
+ */
+ PEM_read_bio_X509(bio, &cert, 0, NULL);
+ if(cert == NULL)
+ printf("PEM_read_bio_X509 failed...n");
+
+ /* get a pointer to the X509 certificate store (which may be empty!) */
+ store=SSL_CTX_get_cert_store((SSL_CTX *)sslctx);
+
+ /* add our certificate to this store */
+ if(X509_STORE_add_cert(store, cert)==0)
+ printf("error adding certificaten");
+
+ /* decrease reference counts */
+ X509_free(cert);
+ BIO_free(bio);
+
+ /* all set to go */
+ return CURLE_OK;
+}
+
+int main(void)
+{
+ CURL * ch;
+ CURLcode rv;
+
+ rv=curl_global_init(CURL_GLOBAL_ALL);
+ ch=curl_easy_init();
+ rv=curl_easy_setopt(ch, CURLOPT_SSLCERTTYPE, "PEM");
+ rv=curl_easy_setopt(ch, CURLOPT_SSL_VERIFYPEER, 1L);
+ rv=curl_easy_setopt(ch, CURLOPT_URL, "https://www.example.com/");
+
+ /* Retrieve page using cacerts' certificate -> will succeed
+ * load the certificate by installing a function doing the nescessary
+ * "modifications" to the SSL CONTEXT just before link init
+ */
+ rv=curl_easy_setopt(ch, CURLOPT_SSL_CTX_FUNCTION, *sslctx_function);
+ rv=curl_easy_perform(ch);
+ if(rv==CURLE_OK)
+ printf("*** transfer succeeded ***n");
+ else
+ printf("*** transfer failed ***n");
+
+ curl_easy_cleanup(ch);
+ curl_global_cleanup();
+ return rv;
+}
+</pre>
+
+<p class="level0"><a name="AVAILABILITY"></a><h2 class="nroffsh">AVAILABILITY</h2>
<p class="level0">Added in 7.11.0 for OpenSSL. Added in 7.42.0 for wolfSSL/CyaSSL. Other SSL backends not supported. <a name="RETURN"></a><h2 class="nroffsh">RETURN VALUE</h2>
<p class="level0">Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not. <a name="SEE"></a><h2 class="nroffsh">SEE ALSO</h2>
-<p class="level0"><a Class="manpage" href="./CURLOPT_SSL_CTX_DATA.html">CURLOPT_SSL_CTX_DATA</a>, <a Class="manpage" href="./CURLOPT_SSL_VERIFYPEER.html">CURLOPT_SSL_VERIFYPEER</a>
, <span Class="manpage"> </span> <p class="roffit">
+<p class="level0"><a Class="manpage" href="./CURLOPT_SSL_CTX_DATA.html">CURLOPT_SSL_CTX_DATA</a>, <a Class="manpage" href="./CURLOPT_SSL_VERIFYPEER.html">CURLOPT_SSL_VERIFYPEER</a><p class="roffit">
This HTML page was made with <a href="http://daniel.haxx.se/projects/roffit/">roffit</a>.
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