Manpages - CURLOPT_SSL_CTX_DATA.3

CURLOPT_SSL_CTX_DATA - pointer passed to ssl_ctx callback

#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SSL_CTX_DATA, void *pointer);

Data pointer to pass to the ssl context callback set by the option CURLOPT_SSL_CTX_FUNCTION(3), this is the pointer you will get as third parameter.

NULL

All TLS based protocols: HTTPS, FTPS, IMAPS, POP3S, SMTPS etc.

  /* 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 = parm;
    /* 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 certificate\n");

    /* decrease reference counts */
    X509_free(cert);
    BIO_free(bio);

    /* all set to go */
    return CURLE_OK;
  }

  int main(void)
  {
    CURL * ch;
    CURLcode rv;
    char *mypem = /* example CA cert PEM - shortened */
      "-----BEGIN CERTIFICATE-----\n"
      "MIIHPTCCBSWgAwIBAgIBADANBgkqhkiG9w0BAQQFADB5MRAwDgYDVQQKEwdSb290\n"
      "IENBMR4wHAYDVQQLExVodHRwOi8vd3d3LmNhY2VydC5vcmcxIjAgBgNVBAMTGUNB\n"
      "IENlcnQgU2lnbmluZyBBdXRob3JpdHkxITAfBgkqhkiG9w0BCQEWEnN1cHBvcnRA\n"
      "Y2FjZXJ0Lm9yZzAeFw0wMzAzMzAxMjI5NDlaFw0zMzAzMjkxMjI5NDlaMHkxEDAO\n"
      "GCSNe9FINSkYQKyTYOGWhlC0elnYjyELn8+CkcY7v2vcB5G5l1YjqrZslMZIBjzk\n"
      "zk6q5PYvCdxTby78dOs6Y5nCpqyJvKeyRKANihDjbPIky/qbn3BHLt4Ui9SyIAmW\n"
      "omTxJBzcoTWcFbLUvFUufQb1nA5V9FrWk9p2rSVzTMVD\n"
      "-----END CERTIFICATE-----\n";

    curl_global_init(CURL_GLOBAL_ALL);
    ch = curl_easy_init();

    curl_easy_setopt(ch, CURLOPT_SSLCERTTYPE, "PEM");
    curl_easy_setopt(ch, CURLOPT_SSL_VERIFYPEER, 1L);
    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 necessary
     * "modifications" to the SSL CONTEXT just before link init
     */
    curl_easy_setopt(ch, CURLOPT_SSL_CTX_FUNCTION, *sslctx_function);
    curl_easy_setopt(ch, CURLOPT_SSL_CTX_DATA, mypem);
    rv = curl_easy_perform(ch);
    if(!rv)
      printf("*** transfer succeeded ***\n");
    else
      printf("*** transfer failed ***\n");

    curl_easy_cleanup(ch);
    curl_global_cleanup();
    return rv;
  }

Added in 7.11.0 for OpenSSL, in 7.42.0 for wolfSSL and in 7.54.0 for mbedTLS. Other SSL backends are not supported.

CURLE_OK if supported; or an error such as:

CURLE_NOT_BUILT_IN - Not supported by the SSL backend

CURLE_UNKNOWN_OPTION

*CURLOPT_SSL_CTX_FUNCTION*(3), *CURLOPT_SSLVERSION*(3),