Commit a0f3eaf2 authored by Jay Satiro's avatar Jay Satiro
Browse files

examples/cacertinmem: ignore cert-already-exists error 

- Ignore X509_R_CERT_ALREADY_IN_HASH_TABLE errors in the CTX callback
  since it's possible the cert may have already been loaded by libcurl.

- Remove the EXAMPLE code in the CURLOPT_SSL_CTX_FUNCTION.3 doc.
  Instead have it direct the reader to this cacertinmem.c example.

- Fix the CA certificate to use the right CA for example.com, Digicert.

Bug: https://curl.haxx.se/mail/lib-2017-12/0057.html
Reported-by: Thomas van Hesteren

Closes https://github.com/curl/curl/pull/2182
parent 859ac360

docs/examples/cacertinmem.c

+90 −53
Original line number Diff line number Diff line
@@ -24,85 +24,103 @@ 
 * </DESC>

 */



#include <openssl/err.h>

#include <openssl/ssl.h>

#include <curl/curl.h>

#include <stdio.h>



size_t writefunction(void *ptr, size_t size, size_t nmemb, void *stream)

{

  fwrite(ptr, size, nmemb, stream);

  fwrite(ptr, size, nmemb, (FILE *)stream);

  return (nmemb*size);

}



static CURLcode sslctx_function(CURL *curl, void *sslctx, void *parm)

{

  X509_STORE *store;

  CURLcode rv = CURLE_ABORTED_BY_CALLBACK;

  X509_STORE *store = NULL;

  X509 *cert = NULL;

  BIO *bio;

  char *mypem = /* www.cacert.org */

    "-----BEGIN CERTIFICATE-----\n"\

    "MIIHPTCCBSWgAwIBAgIBADANBgkqhkiG9w0BAQQFADB5MRAwDgYDVQQKEwdSb290\n"\

    "IENBMR4wHAYDVQQLExVodHRwOi8vd3d3LmNhY2VydC5vcmcxIjAgBgNVBAMTGUNB\n"\

    "IENlcnQgU2lnbmluZyBBdXRob3JpdHkxITAfBgkqhkiG9w0BCQEWEnN1cHBvcnRA\n"\

    "Y2FjZXJ0Lm9yZzAeFw0wMzAzMzAxMjI5NDlaFw0zMzAzMjkxMjI5NDlaMHkxEDAO\n"\

    "BgNVBAoTB1Jvb3QgQ0ExHjAcBgNVBAsTFWh0dHA6Ly93d3cuY2FjZXJ0Lm9yZzEi\n"\

    "MCAGA1UEAxMZQ0EgQ2VydCBTaWduaW5nIEF1dGhvcml0eTEhMB8GCSqGSIb3DQEJ\n"\

    "ARYSc3VwcG9ydEBjYWNlcnQub3JnMIICIjANBgkqhkiG9w0BAQEFAAOCAg8AMIIC\n"\

    "CgKCAgEAziLA4kZ97DYoB1CW8qAzQIxL8TtmPzHlawI229Z89vGIj053NgVBlfkJ\n"\

    "8BLPRoZzYLdufujAWGSuzbCtRRcMY/pnCujW0r8+55jE8Ez64AO7NV1sId6eINm6\n"\

    "zWYyN3L69wj1x81YyY7nDl7qPv4coRQKFWyGhFtkZip6qUtTefWIonvuLwphK42y\n"\

    "fk1WpRPs6tqSnqxEQR5YYGUFZvjARL3LlPdCfgv3ZWiYUQXw8wWRBB0bF4LsyFe7\n"\

    "w2t6iPGwcswlWyCR7BYCEo8y6RcYSNDHBS4CMEK4JZwFaz+qOqfrU0j36NK2B5jc\n"\

    "G8Y0f3/JHIJ6BVgrCFvzOKKrF11myZjXnhCLotLddJr3cQxyYN/Nb5gznZY0dj4k\n"\

    "epKwDpUeb+agRThHqtdB7Uq3EvbXG4OKDy7YCbZZ16oE/9KTfWgu3YtLq1i6L43q\n"\

    "laegw1SJpfvbi1EinbLDvhG+LJGGi5Z4rSDTii8aP8bQUWWHIbEZAWV/RRyH9XzQ\n"\

    "QUxPKZgh/TMfdQwEUfoZd9vUFBzugcMd9Zi3aQaRIt0AUMyBMawSB3s42mhb5ivU\n"\

    "fslfrejrckzzAeVLIL+aplfKkQABi6F1ITe1Yw1nPkZPcCBnzsXWWdsC4PDSy826\n"\

    "YreQQejdIOQpvGQpQsgi3Hia/0PsmBsJUUtaWsJx8cTLc6nloQsCAwEAAaOCAc4w\n"\

    "ggHKMB0GA1UdDgQWBBQWtTIb1Mfz4OaO873SsDrusjkY0TCBowYDVR0jBIGbMIGY\n"\

    "gBQWtTIb1Mfz4OaO873SsDrusjkY0aF9pHsweTEQMA4GA1UEChMHUm9vdCBDQTEe\n"\

    "MBwGA1UECxMVaHR0cDovL3d3dy5jYWNlcnQub3JnMSIwIAYDVQQDExlDQSBDZXJ0\n"\

    "IFNpZ25pbmcgQXV0aG9yaXR5MSEwHwYJKoZIhvcNAQkBFhJzdXBwb3J0QGNhY2Vy\n"\

    "dC5vcmeCAQAwDwYDVR0TAQH/BAUwAwEB/zAyBgNVHR8EKzApMCegJaAjhiFodHRw\n"\

    "czovL3d3dy5jYWNlcnQub3JnL3Jldm9rZS5jcmwwMAYJYIZIAYb4QgEEBCMWIWh0\n"\

    "dHBzOi8vd3d3LmNhY2VydC5vcmcvcmV2b2tlLmNybDA0BglghkgBhvhCAQgEJxYl\n"\

    "aHR0cDovL3d3dy5jYWNlcnQub3JnL2luZGV4LnBocD9pZD0xMDBWBglghkgBhvhC\n"\

    "AQ0ESRZHVG8gZ2V0IHlvdXIgb3duIGNlcnRpZmljYXRlIGZvciBGUkVFIGhlYWQg\n"\

    "b3ZlciB0byBodHRwOi8vd3d3LmNhY2VydC5vcmcwDQYJKoZIhvcNAQEEBQADggIB\n"\

    "ACjH7pyCArpcgBLKNQodgW+JapnM8mgPf6fhjViVPr3yBsOQWqy1YPaZQwGjiHCc\n"\

    "nWKdpIevZ1gNMDY75q1I08t0AoZxPuIrA2jxNGJARjtT6ij0rPtmlVOKTV39O9lg\n"\

    "18p5aTuxZZKmxoGCXJzN600BiqXfEVWqFcofN8CCmHBh22p8lqOOLlQ+TyGpkO/c\n"\

    "gr/c6EWtTZBzCDyUZbAEmXZ/4rzCahWqlwQ3JNgelE5tDlG+1sSPypZt90Pf6DBl\n"\

    "Jzt7u0NDY8RD97LsaMzhGY4i+5jhe1o+ATc7iwiwovOVThrLm82asduycPAtStvY\n"\

    "sONvRUgzEv/+PDIqVPfE94rwiCPCR/5kenHA0R6mY7AHfqQv0wGP3J8rtsYIqQ+T\n"\

    "SCX8Ev2fQtzzxD72V7DX3WnRBnc0CkvSyqD/HMaMyRa+xMwyN2hzXwj7UfdJUzYF\n"\

    "CpUCTPJ5GhD22Dp1nPMd8aINcGeGG7MW9S/lpOt5hvk9C8JzC6WZrG/8Z7jlLwum\n"\

    "GCSNe9FINSkYQKyTYOGWhlC0elnYjyELn8+CkcY7v2vcB5G5l1YjqrZslMZIBjzk\n"\

    "zk6q5PYvCdxTby78dOs6Y5nCpqyJvKeyRKANihDjbPIky/qbn3BHLt4Ui9SyIAmW\n"\

    "omTxJBzcoTWcFbLUvFUufQb1nA5V9FrWk9p2rSVzTMVD\n"\

  BIO *bio = NULL;

  char *mypem =

    /* CA for example.com. CN = DigiCert High Assurance EV Root CA */

    "-----BEGIN CERTIFICATE-----\n"

    "MIIDxTCCAq2gAwIBAgIQAqxcJmoLQJuPC3nyrkYldzANBgkqhkiG9w0BAQUFADBs\n"

    "MQswCQYDVQQGEwJVUzEVMBMGA1UEChMMRGlnaUNlcnQgSW5jMRkwFwYDVQQLExB3\n"

    "d3cuZGlnaWNlcnQuY29tMSswKQYDVQQDEyJEaWdpQ2VydCBIaWdoIEFzc3VyYW5j\n"

    "ZSBFViBSb290IENBMB4XDTA2MTExMDAwMDAwMFoXDTMxMTExMDAwMDAwMFowbDEL\n"

    "MAkGA1UEBhMCVVMxFTATBgNVBAoTDERpZ2lDZXJ0IEluYzEZMBcGA1UECxMQd3d3\n"

    "LmRpZ2ljZXJ0LmNvbTErMCkGA1UEAxMiRGlnaUNlcnQgSGlnaCBBc3N1cmFuY2Ug\n"

    "RVYgUm9vdCBDQTCCASIwDQYJKoZIhvcNAQEBBQADggEPADCCAQoCggEBAMbM5XPm\n"

    "+9S75S0tMqbf5YE/yc0lSbZxKsPVlDRnogocsF9ppkCxxLeyj9CYpKlBWTrT3JTW\n"

    "PNt0OKRKzE0lgvdKpVMSOO7zSW1xkX5jtqumX8OkhPhPYlG++MXs2ziS4wblCJEM\n"

    "xChBVfvLWokVfnHoNb9Ncgk9vjo4UFt3MRuNs8ckRZqnrG0AFFoEt7oT61EKmEFB\n"

    "Ik5lYYeBQVCmeVyJ3hlKV9Uu5l0cUyx+mM0aBhakaHPQNAQTXKFx01p8VdteZOE3\n"

    "hzBWBOURtCmAEvF5OYiiAhF8J2a3iLd48soKqDirCmTCv2ZdlYTBoSUeh10aUAsg\n"

    "EsxBu24LUTi4S8sCAwEAAaNjMGEwDgYDVR0PAQH/BAQDAgGGMA8GA1UdEwEB/wQF\n"

    "MAMBAf8wHQYDVR0OBBYEFLE+w2kD+L9HAdSYJhoIAu9jZCvDMB8GA1UdIwQYMBaA\n"

    "FLE+w2kD+L9HAdSYJhoIAu9jZCvDMA0GCSqGSIb3DQEBBQUAA4IBAQAcGgaX3Nec\n"

    "nzyIZgYIVyHbIUf4KmeqvxgydkAQV8GK83rZEWWONfqe/EW1ntlMMUu4kehDLI6z\n"

    "eM7b41N5cdblIZQB2lWHmiRk9opmzN6cN82oNLFpmyPInngiK3BD41VHMWEZ71jF\n"

    "hS9OMPagMRYjyOfiZRYzy78aG6A9+MpeizGLYAiJLQwGXFK3xPkKmNEVX58Svnw2\n"

    "Yzi9RKR/5CYrCsSXaQ3pjOLAEFe4yHYSkVXySGnYvCoCWw9E1CAx2/S6cCZdkGCe\n"

    "vEsXCS+0yx5DaMkHJ8HSXPfqIbloEpw8nL+e/IBcm2PN7EeqJSdnoDfzAIJ9VNep\n"

    "+OkuE6N36B9K\n"

    "-----END CERTIFICATE-----\n";



  /* clear the current thread's OpenSSL error queue */

  ERR_clear_error();



  /* get a BIO */

  bio = BIO_new_mem_buf(mypem, -1);

  if(!bio)

    goto err;



  /* 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");

  if(!PEM_read_bio_X509(bio, &cert, 0, NULL))

    goto err;



  /* get a pointer to the X509 certificate store (which may be empty!) */

  store = SSL_CTX_get_cert_store((SSL_CTX *)sslctx);

  if(!store)

    goto err;



  /* add our certificate to this store */

  if(X509_STORE_add_cert(store, cert) == 0)

    printf("error adding certificate\n");

  if(!X509_STORE_add_cert(store, cert)) {

    unsigned long error = ERR_peek_last_error();



    /* Ignore error X509_R_CERT_ALREADY_IN_HASH_TABLE which means the

     * certificate is already in the store. That could happen if

     * libcurl already loaded the certificate from a ca cert bundle

     * set at libcurl build-time or runtime.

     */

    if(ERR_GET_LIB(error) != ERR_LIB_X509 ||

       ERR_GET_REASON(error) != X509_R_CERT_ALREADY_IN_HASH_TABLE)

      goto err;



    ERR_clear_error();

  }



  rv = CURLE_OK;



err:

  if(rv != CURLE_OK) {

    char errbuf[256];

    unsigned long error = ERR_peek_last_error();



    fprintf(stderr, "error adding certificate\n");

    if(error) {

      ERR_error_string_n(error, errbuf, sizeof errbuf);

      fprintf(stderr, "%s\n", errbuf);

    }

  }



  /* decrease reference counts */

  X509_free(cert);

  BIO_free(bio);

  ERR_clear_error();



  /* all set to go */

  return CURLE_OK;

  return rv;

}



int main(void)
@@ -124,7 +142,15 @@ int main(void) 
  rv = curl_easy_setopt(ch, CURLOPT_SSL_VERIFYPEER, 1L);

  rv = curl_easy_setopt(ch, CURLOPT_URL, "https://www.example.com/");



  /* first try: retrieve page without cacerts' certificate -> will fail

  /* turn off the default CA locations (optional)

   * otherwise libcurl will load CA certificates from the locations that

   * were detected/specified at build-time

   */

  rv = curl_easy_setopt(ch, CURLOPT_CAINFO, NULL);

  rv = curl_easy_setopt(ch, CURLOPT_CAPATH, NULL);



  /* first try: retrieve page without ca certificates -> should fail

   * unless libcurl was built --with-ca-fallback enabled at build-time

   */

  rv = curl_easy_perform(ch);

  if(rv == CURLE_OK)
@@ -132,6 +158,17 @@ int main(void) 
  else

    printf("*** transfer failed ***\n");



  /* use a fresh connection (optional)

   * this option seriously impacts performance of multiple transfers but

   * it is necessary order to demonstrate this example. recall that the

   * ssl ctx callback is only called _before_ an SSL connection is

   * established, therefore it will not affect existing verified SSL

   * connections already in the connection cache associated with this

   * handle. normally you would set the ssl ctx function before making

   * any transfers, and not use this option.

   */

  rv = curl_easy_setopt(ch, CURLOPT_FRESH_CONNECT, 1L);



  /* second try: 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

docs/libcurl/opts/CURLOPT_SSL_CTX_FUNCTION.3

+2 −72
Original line number Diff line number Diff line
@@ -62,79 +62,9 @@ NULL 
.SH PROTOCOLS

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

.SH EXAMPLE

.nf

/* 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"

    "MIIHPTCCBSWgAwIBAgIBADANBgkqhkiG9w0BAQQFADB5MRAwDgYDVQQKEwdSb290\\n"

    "IENBMR4wHAYDVQQLExVodHRwOi8vd3d3LmNhY2VydC5vcmcxIjAgBgNVBAMTGUNB\\n"

    "IENlcnQgU2lnbmluZyBBdXRob3JpdHkxITAfBgkqhkiG9w0BCQEWEnN1cHBvcnRA\\n"

    "Y2FjZXJ0Lm9yZzAeFw0wMzAzMzAxMjI5NDlaFw0zMzAzMjkxMjI5NDlaMHkxEDAO\\n"

    "GCSNe9FINSkYQKyTYOGWhlC0elnYjyELn8+CkcY7v2vcB5G5l1YjqrZslMZIBjzk\\n"

    "zk6q5PYvCdxTby78dOs6Y5nCpqyJvKeyRKANihDjbPIky/qbn3BHLt4Ui9SyIAmW\\n"

    "omTxJBzcoTWcFbLUvFUufQb1nA5V9FrWk9p2rSVzTMVD\\n"

    "-----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 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;



  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 necessary

   * "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");

See cacertinmem.c in docs/examples directory for usage example.



  curl_easy_cleanup(ch);

  curl_global_cleanup();

  return rv;

}

.fi

https://curl.haxx.se/libcurl/c/cacertinmem.html

.SH AVAILABILITY

Added in 7.11.0 for OpenSSL. Added in 7.42.0 for wolfSSL/CyaSSL. Added in

7.54.0 for mbedTLS. Other SSL backends not supported.