ssluse.c

   be used as the identity. Otherwise, the (most specific) Common Name
   field in the Subject field of the certificate MUST be used. Although
   the use of the Common Name is existing practice, it is deprecated and
   Certification Authorities are encouraged to use the dNSName instead.

   Matching is performed using the matching rules specified by
   [RFC2459].  If more than one identity of a given type is present in
   the certificate (e.g., more than one dNSName name, a match in any one
   of the set is considered acceptable.) Names may contain the wildcard
   character * which is considered to match any single domain name
   component or component fragment. E.g., *.a.com matches foo.a.com but
   not bar.foo.a.com. f*.com matches foo.com but not bar.com.

   In some cases, the URI is specified as an IP address rather than a
   hostname. In this case, the iPAddress subjectAltName must be present
   in the certificate and must exactly match the IP in the URI.

*/
static CURLcode verifyhost(struct connectdata *conn,
                           X509 *server_cert)
{
  bool matched = FALSE; /* no alternative match yet */
  int target = GEN_DNS; /* target type, GEN_DNS or GEN_IPADD */
  int addrlen = 0;
  struct SessionHandle *data = conn->data;
  STACK_OF(GENERAL_NAME) *altnames;
#ifdef ENABLE_IPV6
  struct in6_addr addr;
#else
  struct in_addr addr;
#endif
  CURLcode res = CURLE_OK;

#ifdef ENABLE_IPV6
  if(conn->bits.ipv6_ip &&
     Curl_inet_pton(AF_INET6, conn->host.name, &addr)) {
    target = GEN_IPADD;
    addrlen = sizeof(struct in6_addr);
  }
  else
#endif
    if(Curl_inet_pton(AF_INET, conn->host.name, &addr)) {
      target = GEN_IPADD;
      addrlen = sizeof(struct in_addr);
    }

  /* get a "list" of alternative names */
  altnames = X509_get_ext_d2i(server_cert, NID_subject_alt_name, NULL, NULL);

  if(altnames) {
    int numalts;
    int i;

    /* get amount of alternatives, RFC2459 claims there MUST be at least
       one, but we don't depend on it... */
    numalts = sk_GENERAL_NAME_num(altnames);

    /* loop through all alternatives while none has matched */
    for (i=0; (i<numalts) && !matched; i++) {
      /* get a handle to alternative name number i */
      const GENERAL_NAME *check = sk_GENERAL_NAME_value(altnames, i);

      /* only check alternatives of the same type the target is */
      if(check->type == target) {
        /* get data and length */
        const char *altptr = (char *)ASN1_STRING_data(check->d.ia5);
        int altlen;

        switch(target) {
        case GEN_DNS: /* name/pattern comparison */
          /* The OpenSSL man page explicitly says: "In general it cannot be
             assumed that the data returned by ASN1_STRING_data() is null
             terminated or does not contain embedded nulls." But also that
             "The actual format of the data will depend on the actual string
             type itself: for example for and IA5String the data will be ASCII"

             Gisle researched the OpenSSL sources:
             "I checked the 0.9.6 and 0.9.8 sources before my patch and
             it always 0-terminates an IA5String."
          */
          if(cert_hostcheck(altptr, conn->host.name))
            matched = TRUE;
          break;

        case GEN_IPADD: /* IP address comparison */
          /* compare alternative IP address if the data chunk is the same size
             our server IP address is */
          altlen = ASN1_STRING_length(check->d.ia5);
          if((altlen == addrlen) && !memcmp(altptr, &addr, altlen))
            matched = TRUE;
          break;
        }
      }
    }
    GENERAL_NAMES_free(altnames);
  }

  if(matched)
    /* an alternative name matched the server hostname */
    infof(data, "\t subjectAltName: %s matched\n", conn->host.dispname);
  else {
    /* we have to look to the last occurence of a commonName in the
       distinguished one to get the most significant one. */
    int j,i=-1 ;

/* The following is done because of a bug in 0.9.6b */

    unsigned char *nulstr = (unsigned char *)"";
    unsigned char *peer_CN = nulstr;

    X509_NAME *name = X509_get_subject_name(server_cert) ;
    if(name)
      while((j=X509_NAME_get_index_by_NID(name,NID_commonName,i))>=0)
        i=j;

    /* we have the name entry and we will now convert this to a string
       that we can use for comparison. Doing this we support BMPstring,
       UTF8 etc. */

    if(i>=0) {
      ASN1_STRING *tmp = X509_NAME_ENTRY_get_data(X509_NAME_get_entry(name,i));

      /* In OpenSSL 0.9.7d and earlier, ASN1_STRING_to_UTF8 fails if the input
         is already UTF-8 encoded. We check for this case and copy the raw
         string manually to avoid the problem. This code can be made
         conditional in the future when OpenSSL has been fixed. Work-around
         brought by Alexis S. L. Carvalho. */
      if(tmp && ASN1_STRING_type(tmp) == V_ASN1_UTF8STRING) {
        j = ASN1_STRING_length(tmp);
        if(j >= 0) {
          peer_CN = OPENSSL_malloc(j+1);
          if(peer_CN) {
            memcpy(peer_CN, ASN1_STRING_data(tmp), j);
            peer_CN[j] = '\0';
          }
        }
      }
      else /* not a UTF8 name */
        j = ASN1_STRING_to_UTF8(&peer_CN, tmp);
    }

    if(peer_CN == nulstr)
       peer_CN = NULL;
#ifdef CURL_DOES_CONVERSIONS
    else {
      /* convert peer_CN from UTF8 */
      size_t rc;
      rc = Curl_convert_from_utf8(data, peer_CN, strlen(peer_CN));
      /* Curl_convert_from_utf8 calls failf if unsuccessful */
      if(rc != CURLE_OK) {
        OPENSSL_free(peer_CN);
        return rc;
      }
    }
#endif /* CURL_DOES_CONVERSIONS */

    if(!peer_CN) {
      failf(data,
            "SSL: unable to obtain common name from peer certificate");
      return CURLE_PEER_FAILED_VERIFICATION;
    }
    else if(!cert_hostcheck((const char *)peer_CN, conn->host.name)) {
      if(data->set.ssl.verifyhost > 1) {
        failf(data, "SSL: certificate subject name '%s' does not match "
              "target host name '%s'", peer_CN, conn->host.dispname);
        res = CURLE_PEER_FAILED_VERIFICATION;
      }
      else
        infof(data, "\t common name: %s (does not match '%s')\n",
              peer_CN, conn->host.dispname);
    }
    else {
      infof(data, "\t common name: %s (matched)\n", peer_CN);
    }
    if(peer_CN)
      OPENSSL_free(peer_CN);
  }
  return res;
}
#endif /* USE_SSLEAY */

/* The SSL_CTRL_SET_MSG_CALLBACK doesn't exist in ancient OpenSSL versions
   and thus this cannot be done there. */
#ifdef SSL_CTRL_SET_MSG_CALLBACK

static const char *ssl_msg_type(int ssl_ver, int msg)
{
  if(ssl_ver == SSL2_VERSION_MAJOR) {
    switch (msg) {
      case SSL2_MT_ERROR:
        return "Error";
      case SSL2_MT_CLIENT_HELLO:
        return "Client hello";
      case SSL2_MT_CLIENT_MASTER_KEY:
        return "Client key";
      case SSL2_MT_CLIENT_FINISHED:
        return "Client finished";
      case SSL2_MT_SERVER_HELLO:
        return "Server hello";
      case SSL2_MT_SERVER_VERIFY:
        return "Server verify";
      case SSL2_MT_SERVER_FINISHED:
        return "Server finished";
      case SSL2_MT_REQUEST_CERTIFICATE:
        return "Request CERT";
      case SSL2_MT_CLIENT_CERTIFICATE:
        return "Client CERT";
    }
  }
  else if(ssl_ver == SSL3_VERSION_MAJOR) {
    switch (msg) {
      case SSL3_MT_HELLO_REQUEST:
        return "Hello request";
      case SSL3_MT_CLIENT_HELLO:
        return "Client hello";
      case SSL3_MT_SERVER_HELLO:
        return "Server hello";
      case SSL3_MT_CERTIFICATE:
        return "CERT";
      case SSL3_MT_SERVER_KEY_EXCHANGE:
        return "Server key exchange";
      case SSL3_MT_CLIENT_KEY_EXCHANGE:
        return "Client key exchange";
      case SSL3_MT_CERTIFICATE_REQUEST:
        return "Request CERT";
      case SSL3_MT_SERVER_DONE:
        return "Server finished";
      case SSL3_MT_CERTIFICATE_VERIFY:
        return "CERT verify";
      case SSL3_MT_FINISHED:
        return "Finished";
    }
  }
  return "Unknown";
}

static const char *tls_rt_type(int type)
{
  return (
    type == SSL3_RT_CHANGE_CIPHER_SPEC ? "TLS change cipher, " :
    type == SSL3_RT_ALERT              ? "TLS alert, "         :
    type == SSL3_RT_HANDSHAKE          ? "TLS handshake, "     :
    type == SSL3_RT_APPLICATION_DATA   ? "TLS app data, "      :
                                         "TLS Unknown, ");
}


/*
 * Our callback from the SSL/TLS layers.
 */
static void ssl_tls_trace(int direction, int ssl_ver, int content_type,
                          const void *buf, size_t len, const SSL *ssl,
                          struct connectdata *conn)
{
  struct SessionHandle *data;
  const char *msg_name, *tls_rt_name;
  char ssl_buf[1024];
  int  ver, msg_type, txt_len;

  if(!conn || !conn->data || !conn->data->set.fdebug ||
      (direction != 0 && direction != 1))
    return;

  data = conn->data;
  ssl_ver >>= 8;
  ver = (ssl_ver == SSL2_VERSION_MAJOR ? '2' :
         ssl_ver == SSL3_VERSION_MAJOR ? '3' : '?');

  /* SSLv2 doesn't seem to have TLS record-type headers, so OpenSSL
   * always pass-up content-type as 0. But the interesting message-type
   * is at 'buf[0]'.
   */
  if(ssl_ver == SSL3_VERSION_MAJOR && content_type != 0)
    tls_rt_name = tls_rt_type(content_type);
  else
    tls_rt_name = "";

  msg_type = *(char*)buf;
  msg_name = ssl_msg_type(ssl_ver, msg_type);

  txt_len = snprintf(ssl_buf, sizeof(ssl_buf), "SSLv%c, %s%s (%d):\n",
                     ver, tls_rt_name, msg_name, msg_type);
  Curl_debug(data, CURLINFO_TEXT, ssl_buf, (size_t)txt_len, NULL);

  Curl_debug(data, (direction == 1) ? CURLINFO_SSL_DATA_OUT :
             CURLINFO_SSL_DATA_IN, (char *)buf, len, NULL);
  (void) ssl;
}
#endif

#ifdef USE_SSLEAY
/* ====================================================== */

static CURLcode
ossl_connect_step1(struct connectdata *conn,
                   int sockindex)
{
  CURLcode retcode = CURLE_OK;

  struct SessionHandle *data = conn->data;
  SSL_METHOD_QUAL SSL_METHOD *req_method=NULL;
  void *ssl_sessionid=NULL;
  X509_LOOKUP *lookup=NULL;
  curl_socket_t sockfd = conn->sock[sockindex];
  struct ssl_connect_data *connssl = &conn->ssl[sockindex];
#ifdef SSL_CTRL_SET_TLSEXT_HOSTNAME
#ifdef ENABLE_IPV6
  struct in6_addr addr;
#else
  struct in_addr addr;
#endif
#endif

  DEBUGASSERT(ssl_connect_1 == connssl->connecting_state);

  /* Make funny stuff to get random input */
  Curl_ossl_seed(data);

  /* check to see if we've been told to use an explicit SSL/TLS version */
  switch(data->set.ssl.version) {
  default:
  case CURL_SSLVERSION_DEFAULT:
    /* we try to figure out version */
    req_method = SSLv23_client_method();
    break;
  case CURL_SSLVERSION_TLSv1:
    req_method = TLSv1_client_method();
    break;
  case CURL_SSLVERSION_SSLv2:
    req_method = SSLv2_client_method();
    break;
  case CURL_SSLVERSION_SSLv3:
    req_method = SSLv3_client_method();
    break;
  }

  if(connssl->ctx)
    SSL_CTX_free(connssl->ctx);
  connssl->ctx = SSL_CTX_new(req_method);

  if(!connssl->ctx) {
    failf(data, "SSL: couldn't create a context!");
    return CURLE_OUT_OF_MEMORY;
  }

#ifdef SSL_CTRL_SET_MSG_CALLBACK
  if(data->set.fdebug && data->set.verbose) {
    /* the SSL trace callback is only used for verbose logging so we only
       inform about failures of setting it */
    if(!SSL_CTX_callback_ctrl(connssl->ctx, SSL_CTRL_SET_MSG_CALLBACK,
                               (void (*)(void))ssl_tls_trace)) {
      infof(data, "SSL: couldn't set callback!\n");
    }
    else if(!SSL_CTX_ctrl(connssl->ctx, SSL_CTRL_SET_MSG_CALLBACK_ARG, 0,
                           conn)) {
      infof(data, "SSL: couldn't set callback argument!\n");
    }
  }
#endif

  /* OpenSSL contains code to work-around lots of bugs and flaws in various
     SSL-implementations. SSL_CTX_set_options() is used to enabled those
     work-arounds. The man page for this option states that SSL_OP_ALL enables
     all the work-arounds and that "It is usually safe to use SSL_OP_ALL to
     enable the bug workaround options if compatibility with somewhat broken
     implementations is desired."

  */
  SSL_CTX_set_options(connssl->ctx, SSL_OP_ALL);

  /* disable SSLv2 in the default case (i.e. allow SSLv3 and TLSv1) */
  if(data->set.ssl.version == CURL_SSLVERSION_DEFAULT)
    SSL_CTX_set_options(connssl->ctx, SSL_OP_NO_SSLv2);

#if 0
  /*
   * Not sure it's needed to tell SSL_connect() that socket is
   * non-blocking. It doesn't seem to care, but just return with
   * SSL_ERROR_WANT_x.
   */
  if(data->state.used_interface == Curl_if_multi)
    SSL_CTX_ctrl(connssl->ctx, BIO_C_SET_NBIO, 1, NULL);
#endif

  if(data->set.str[STRING_CERT]) {
    if(!cert_stuff(conn,
                   connssl->ctx,
                   data->set.str[STRING_CERT],
                   data->set.str[STRING_CERT_TYPE],
                   data->set.str[STRING_KEY],
                   data->set.str[STRING_KEY_TYPE])) {
      /* failf() is already done in cert_stuff() */
      return CURLE_SSL_CERTPROBLEM;
    }
  }

  if(data->set.str[STRING_SSL_CIPHER_LIST]) {
    if(!SSL_CTX_set_cipher_list(connssl->ctx,
                                data->set.str[STRING_SSL_CIPHER_LIST])) {
      failf(data, "failed setting cipher list");
      return CURLE_SSL_CIPHER;
    }
  }

  if(data->set.str[STRING_SSL_CAFILE] || data->set.str[STRING_SSL_CAPATH]) {
    /* tell SSL where to find CA certificates that are used to verify
       the servers certificate. */
    if(!SSL_CTX_load_verify_locations(connssl->ctx,
                                       data->set.str[STRING_SSL_CAFILE],
                                       data->set.str[STRING_SSL_CAPATH])) {
      if(data->set.ssl.verifypeer) {
        /* Fail if we insist on successfully verifying the server. */
        failf(data,"error setting certificate verify locations:\n"
              "  CAfile: %s\n  CApath: %s\n",
              data->set.str[STRING_SSL_CAFILE]?
              data->set.str[STRING_SSL_CAFILE]: "none",
              data->set.str[STRING_SSL_CAPATH]?
              data->set.str[STRING_SSL_CAPATH] : "none");
        return CURLE_SSL_CACERT_BADFILE;
      }
      else {
        /* Just continue with a warning if no strict  certificate verification
           is required. */
        infof(data, "error setting certificate verify locations,"
              " continuing anyway:\n");
      }
    }
    else {
      /* Everything is fine. */
      infof(data, "successfully set certificate verify locations:\n");
    }
    infof(data,
          "  CAfile: %s\n"
          "  CApath: %s\n",
          data->set.str[STRING_SSL_CAFILE] ? data->set.str[STRING_SSL_CAFILE]:
          "none",
          data->set.str[STRING_SSL_CAPATH] ? data->set.str[STRING_SSL_CAPATH]:
          "none");
  }

  if (data->set.str[STRING_SSL_CRLFILE]) {
    /* tell SSL where to find CRL file that is used to check certificate
     * revocation */
    lookup=X509_STORE_add_lookup(connssl->ctx->cert_store,X509_LOOKUP_file());
    if ( !lookup ||
         (X509_load_crl_file(lookup,data->set.str[STRING_SSL_CRLFILE],
			     X509_FILETYPE_PEM)!=1) ) {
      failf(data,"error loading CRL file :\n"
            "  CRLfile: %s\n",
            data->set.str[STRING_SSL_CRLFILE]?
            data->set.str[STRING_SSL_CRLFILE]: "none");
      return CURLE_SSL_CRL_BADFILE;
    }
    else {
      /* Everything is fine. */
      infof(data, "successfully load CRL file:\n");
      X509_STORE_set_flags(connssl->ctx->cert_store,
			   X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL);
    }
    infof(data,
          "  CRLfile: %s\n", data->set.str[STRING_SSL_CRLFILE] ?
	  data->set.str[STRING_SSL_CRLFILE]: "none");
  }

  /* SSL always tries to verify the peer, this only says whether it should
   * fail to connect if the verification fails, or if it should continue
   * anyway. In the latter case the result of the verification is checked with
   * SSL_get_verify_result() below. */
  SSL_CTX_set_verify(connssl->ctx,
                     data->set.ssl.verifypeer?SSL_VERIFY_PEER:SSL_VERIFY_NONE,
                     cert_verify_callback);

  /* give application a chance to interfere with SSL set up. */
  if(data->set.ssl.fsslctx) {
    retcode = (*data->set.ssl.fsslctx)(data, connssl->ctx,
                                       data->set.ssl.fsslctxp);
    if(retcode) {
      failf(data,"error signaled by ssl ctx callback");
      return retcode;
    }
  }

  /* Lets make an SSL structure */
  if(connssl->handle)
    SSL_free(connssl->handle);
  connssl->handle = SSL_new(connssl->ctx);
  if(!connssl->handle) {
    failf(data, "SSL: couldn't create a context (handle)!");
    return CURLE_OUT_OF_MEMORY;
  }
  SSL_set_connect_state(connssl->handle);

  connssl->server_cert = 0x0;

#ifdef SSL_CTRL_SET_TLSEXT_HOSTNAME
  if ((0 == Curl_inet_pton(AF_INET, conn->host.name, &addr)) &&
#ifdef ENABLE_IPV6
      (0 == Curl_inet_pton(AF_INET6, conn->host.name, &addr)) &&
#endif
      !SSL_set_tlsext_host_name(connssl->handle, conn->host.name))
    infof(data, "WARNING: failed to configure server name indication (SNI) "
          "TLS extension\n");
#endif

  /* Check if there's a cached ID we can/should use here! */
  if(!Curl_ssl_getsessionid(conn, &ssl_sessionid, NULL)) {
    /* we got a session id, use it! */
    if(!SSL_set_session(connssl->handle, ssl_sessionid)) {
      failf(data, "SSL: SSL_set_session failed: %s",
            ERR_error_string(ERR_get_error(),NULL));
      return CURLE_SSL_CONNECT_ERROR;
    }
    /* Informational message */
    infof (data, "SSL re-using session ID\n");
  }

  /* pass the raw socket into the SSL layers */
  if(!SSL_set_fd(connssl->handle, sockfd)) {
     failf(data, "SSL: SSL_set_fd failed: %s",
           ERR_error_string(ERR_get_error(),NULL));
     return CURLE_SSL_CONNECT_ERROR;
  }

  connssl->connecting_state = ssl_connect_2;
  return CURLE_OK;
}

static CURLcode
ossl_connect_step2(struct connectdata *conn, int sockindex)
{
  struct SessionHandle *data = conn->data;
  int err;
  struct ssl_connect_data *connssl = &conn->ssl[sockindex];

  DEBUGASSERT(ssl_connect_2 == connssl->connecting_state
             || ssl_connect_2_reading == connssl->connecting_state
             || ssl_connect_2_writing == connssl->connecting_state);

  err = SSL_connect(connssl->handle);

  /* 1  is fine
     0  is "not successful but was shut down controlled"
     <0 is "handshake was not successful, because a fatal error occurred" */
  if(1 != err) {
    int detail = SSL_get_error(connssl->handle, err);

    if(SSL_ERROR_WANT_READ == detail) {
      connssl->connecting_state = ssl_connect_2_reading;
      return CURLE_OK;
    }
    else if(SSL_ERROR_WANT_WRITE == detail) {
      connssl->connecting_state = ssl_connect_2_writing;
      return CURLE_OK;
    }
    else {
      /* untreated error */
      unsigned long errdetail;
      char error_buffer[256]; /* OpenSSL documents that this must be at least
                                 256 bytes long. */
      CURLcode rc;
      const char *cert_problem = NULL;

      connssl->connecting_state = ssl_connect_2; /* the connection failed,
                                                    we're not waiting for
                                                    anything else. */

      errdetail = ERR_get_error(); /* Gets the earliest error code from the
                                      thread's error queue and removes the
                                      entry. */

      switch(errdetail) {
      case 0x1407E086:
        /* 1407E086:
           SSL routines:
           SSL2_SET_CERTIFICATE:
           certificate verify failed */
        /* fall-through */
      case 0x14090086:
        /* 14090086:
           SSL routines:
           SSL3_GET_SERVER_CERTIFICATE:
           certificate verify failed */
        cert_problem = "SSL certificate problem, verify that the CA cert is"
          " OK. Details:\n";
        rc = CURLE_SSL_CACERT;
        break;
      default:
        rc = CURLE_SSL_CONNECT_ERROR;
        break;
      }

      /* detail is already set to the SSL error above */

      /* If we e.g. use SSLv2 request-method and the server doesn't like us
       * (RST connection etc.), OpenSSL gives no explanation whatsoever and
       * the SO_ERROR is also lost.
       */
      if(CURLE_SSL_CONNECT_ERROR == rc && errdetail == 0) {
        failf(data, "Unknown SSL protocol error in connection to %s:%d ",
              conn->host.name, conn->port);
        return rc;
      }
      /* Could be a CERT problem */

      SSL_strerror(errdetail, error_buffer, sizeof(error_buffer));
      failf(data, "%s%s", cert_problem ? cert_problem : "", error_buffer);
      return rc;
    }
  }
  else {
    /* we have been connected fine, we're not waiting for anything else. */
    connssl->connecting_state = ssl_connect_3;

    /* Informational message */
    infof (data, "SSL connection using %s\n",
           SSL_get_cipher(connssl->handle));

    return CURLE_OK;
  }
}

/*
 * Get the server cert, verify it and show it etc, only call failf() if the
 * 'strict' argument is TRUE as otherwise all this is for informational
 * purposes only!
 *
 * We check certificates to authenticate the server; otherwise we risk
 * man-in-the-middle attack.
 */
static CURLcode servercert(struct connectdata *conn,
                           struct ssl_connect_data *connssl,
                           bool strict)
{
  CURLcode retcode = CURLE_OK;
  char *str;
  long lerr;
  ASN1_TIME *certdate;
  struct SessionHandle *data = conn->data;
  X509 *issuer;
  FILE *fp;

  connssl->server_cert = SSL_get_peer_certificate(connssl->handle);
  if(!connssl->server_cert) {
    if(strict)
      failf(data, "SSL: couldn't get peer certificate!");
    return CURLE_PEER_FAILED_VERIFICATION;
  }
  infof (data, "Server certificate:\n");

  str = X509_NAME_oneline(X509_get_subject_name(connssl->server_cert),
                          NULL, 0);
  if(!str) {
    if(strict)
      failf(data, "SSL: couldn't get X509-subject!");
    X509_free(connssl->server_cert);
    connssl->server_cert = NULL;
    return CURLE_SSL_CONNECT_ERROR;
  }
  infof(data, "\t subject: %s\n", str);
  CRYPTO_free(str);

  certdate = X509_get_notBefore(connssl->server_cert);
  asn1_output(conn, "\t start date: ", certdate);

  certdate = X509_get_notAfter(connssl->server_cert);
  asn1_output(conn, "\t expire date: ", certdate);

  if(data->set.ssl.verifyhost) {
    retcode = verifyhost(conn, connssl->server_cert);
    if(retcode) {
      X509_free(connssl->server_cert);
      connssl->server_cert = NULL;
      return retcode;
    }
  }

  str = X509_NAME_oneline(X509_get_issuer_name(connssl->server_cert),
                          NULL, 0);
  if(!str) {
    if(strict)
      failf(data, "SSL: couldn't get X509-issuer name!");
    retcode = CURLE_SSL_CONNECT_ERROR;
  }
  else {
    infof(data, "\t issuer: %s\n", str);
    CRYPTO_free(str);

    /* We could do all sorts of certificate verification stuff here before
       deallocating the certificate. */

    /* e.g. match issuer name with provided issuer certificate */
    if (data->set.str[STRING_SSL_ISSUERCERT]) {
      if (! (fp=fopen(data->set.str[STRING_SSL_ISSUERCERT],"r"))) {
        if (strict)
	  failf(data, "SSL: Unable to open issuer cert (%s)\n",
		data->set.str[STRING_SSL_ISSUERCERT]);
	X509_free(connssl->server_cert);
	connssl->server_cert = NULL;
	return CURLE_SSL_ISSUER_ERROR;
      }
      issuer = PEM_read_X509(fp,NULL,ZERO_NULL,NULL);
      if (!issuer) {
        if (strict)
	  failf(data, "SSL: Unable to read issuer cert (%s)\n",
		data->set.str[STRING_SSL_ISSUERCERT]);
	X509_free(connssl->server_cert);
	X509_free(issuer);
	fclose(fp);
	return CURLE_SSL_ISSUER_ERROR;
      }
      fclose(fp);
      if (X509_check_issued(issuer,connssl->server_cert) != X509_V_OK) {
        if (strict)
	  failf(data, "SSL: Certificate issuer check failed (%s)\n",
		data->set.str[STRING_SSL_ISSUERCERT]);
	X509_free(connssl->server_cert);
	X509_free(issuer);
	connssl->server_cert = NULL;
        return CURLE_SSL_ISSUER_ERROR;
      }
      infof(data, "\t SSL certificate issuer check ok (%s)\n",
	    data->set.str[STRING_SSL_ISSUERCERT]);
      X509_free(issuer);
    }

    lerr = data->set.ssl.certverifyresult=
      SSL_get_verify_result(connssl->handle);
    if(data->set.ssl.certverifyresult != X509_V_OK) {
      if(data->set.ssl.verifypeer) {
        /* We probably never reach this, because SSL_connect() will fail
           and we return earlyer if verifypeer is set? */
        if(strict)
          failf(data, "SSL certificate verify result: %s (%ld)",
                X509_verify_cert_error_string(lerr), lerr);
        retcode = CURLE_PEER_FAILED_VERIFICATION;
      }
      else
        infof(data, "\t SSL certificate verify result: %s (%ld),"
              " continuing anyway.\n",
              X509_verify_cert_error_string(lerr), lerr);
    }
    else
      infof(data, "\t SSL certificate verify ok.\n");
  }

  X509_free(connssl->server_cert);
  connssl->server_cert = NULL;
  connssl->connecting_state = ssl_connect_done;

  return retcode;
}


static CURLcode
ossl_connect_step3(struct connectdata *conn,
                   int sockindex)
{
  CURLcode retcode = CURLE_OK;
  void *ssl_sessionid=NULL;
  struct SessionHandle *data = conn->data;
  struct ssl_connect_data *connssl = &conn->ssl[sockindex];

  DEBUGASSERT(ssl_connect_3 == connssl->connecting_state);

  if(Curl_ssl_getsessionid(conn, &ssl_sessionid, NULL)) {
    /* Since this is not a cached session ID, then we want to stach this one
       in the cache! */
    SSL_SESSION *our_ssl_sessionid;
#ifdef HAVE_SSL_GET1_SESSION
    our_ssl_sessionid = SSL_get1_session(connssl->handle);

    /* SSL_get1_session() will increment the reference
       count and the session will stay in memory until explicitly freed with
       SSL_SESSION_free(3), regardless of its state.
       This function was introduced in openssl 0.9.5a. */
#else
    our_ssl_sessionid = SSL_get_session(connssl->handle);

    /* if SSL_get1_session() is unavailable, use SSL_get_session().
       This is an inferior option because the session can be flushed
       at any time by openssl. It is included only so curl compiles
       under versions of openssl < 0.9.5a.

       WARNING: How curl behaves if it's session is flushed is
       untested.
    */
#endif
    retcode = Curl_ssl_addsessionid(conn, our_ssl_sessionid,
                                    0 /* unknown size */);
    if(retcode) {
      failf(data, "failed to store ssl session");
      return retcode;
    }
  }


  /*
   * We check certificates to authenticate the server; otherwise we risk
   * man-in-the-middle attack; NEVERTHELESS, if we're told explicitly not to
   * verify the peer ignore faults and failures from the server cert
   * operations.
   */

  if(!data->set.ssl.verifypeer)
    (void)servercert(conn, connssl, FALSE);
  else
    retcode = servercert(conn, connssl, TRUE);

  if(CURLE_OK == retcode)
    connssl->connecting_state = ssl_connect_done;
  return retcode;
}

static CURLcode
ossl_connect_common(struct connectdata *conn,
                    int sockindex,
                    bool nonblocking,
                    bool *done)
{
  CURLcode retcode;
  struct SessionHandle *data = conn->data;
  struct ssl_connect_data *connssl = &conn->ssl[sockindex];
  curl_socket_t sockfd = conn->sock[sockindex];
  long timeout_ms;

  if(ssl_connect_1==connssl->connecting_state) {
    /* Find out how much more time we're allowed */
    timeout_ms = Curl_timeleft(conn, NULL, TRUE);

    if(timeout_ms < 0) {
      /* no need to continue if time already is up */
      failf(data, "SSL connection timeout");
      return CURLE_OPERATION_TIMEDOUT;
    }
    retcode = ossl_connect_step1(conn, sockindex);
    if(retcode)
      return retcode;
  }

  timeout_ms = 0;
  while(ssl_connect_2 == connssl->connecting_state ||
        ssl_connect_2_reading == connssl->connecting_state ||
        ssl_connect_2_writing == connssl->connecting_state) {

    /* check allowed time left */
    timeout_ms = Curl_timeleft(conn, NULL, TRUE);

    if(timeout_ms < 0) {
      /* no need to continue if time already is up */
      failf(data, "SSL connection timeout");
      return CURLE_OPERATION_TIMEDOUT;
    }

    /* if ssl is expecting something, check if it's available. */
    if(connssl->connecting_state == ssl_connect_2_reading
        || connssl->connecting_state == ssl_connect_2_writing) {

      int writefd = ssl_connect_2_writing==
        connssl->connecting_state?sockfd:CURL_SOCKET_BAD;
      int readfd = ssl_connect_2_reading==
        connssl->connecting_state?sockfd:CURL_SOCKET_BAD;

      while(1) {
        int what = Curl_socket_ready(readfd, writefd,
                                     nonblocking?0:(int)timeout_ms);
        if(what > 0)
          /* readable or writable, go loop in the outer loop */
          break;
        else if(0 == what) {
          if(nonblocking) {
            *done = FALSE;
            return CURLE_OK;
          }
          else {
            /* timeout */
            failf(data, "SSL connection timeout");
            return CURLE_OPERATION_TIMEDOUT;
          }
        }
        else {
          /* anything that gets here is fatally bad */
          failf(data, "select/poll on SSL socket, errno: %d", SOCKERRNO);
          return CURLE_SSL_CONNECT_ERROR;
        }
      } /* while()-loop for the select() */
    }

    /* get the timeout from step2 to avoid computing it twice. */
    retcode = ossl_connect_step2(conn, sockindex);
    if(retcode)
      return retcode;

  } /* repeat step2 until all transactions are done. */


  if(ssl_connect_3==connssl->connecting_state) {
    retcode = ossl_connect_step3(conn, sockindex);
    if(retcode)
      return retcode;
  }

  if(ssl_connect_done==connssl->connecting_state) {
    connssl->state = ssl_connection_complete;
    *done = TRUE;
  }
  else
    *done = FALSE;

  /* Reset our connect state machine */
  connssl->connecting_state = ssl_connect_1;

  return CURLE_OK;
}

CURLcode
Curl_ossl_connect_nonblocking(struct connectdata *conn,
                              int sockindex,
                              bool *done)
{
  return ossl_connect_common(conn, sockindex, TRUE, done);
}

CURLcode
Curl_ossl_connect(struct connectdata *conn,
                  int sockindex)
{
  CURLcode retcode;
  bool done = FALSE;

  retcode = ossl_connect_common(conn, sockindex, FALSE, &done);
  if(retcode)
    return retcode;

  DEBUGASSERT(done);

  return CURLE_OK;
}

bool Curl_ossl_data_pending(const struct connectdata *conn,
                            int connindex)
{
  if(conn->ssl[connindex].handle)
    /* SSL is in use */
    return (bool)(0 != SSL_pending(conn->ssl[connindex].handle));
  else
    return FALSE;
}

/* return number of sent (non-SSL) bytes */
ssize_t Curl_ossl_send(struct connectdata *conn,
                       int sockindex,
                       const void *mem,
                       size_t len)
{
  /* SSL_write() is said to return 'int' while write() and send() returns
     'size_t' */
  int err;
  char error_buffer[120]; /* OpenSSL documents that this must be at least 120
                             bytes long. */
  unsigned long sslerror;
  int rc = SSL_write(conn->ssl[sockindex].handle, mem, (int)len);

  if(rc < 0) {
    err = SSL_get_error(conn->ssl[sockindex].handle, rc);

    switch(err) {
    case SSL_ERROR_WANT_READ:
    case SSL_ERROR_WANT_WRITE:
      /* The operation did not complete; the same TLS/SSL I/O function
         should be called again later. This is basicly an EWOULDBLOCK
         equivalent. */
      return 0;
    case SSL_ERROR_SYSCALL:
      failf(conn->data, "SSL_write() returned SYSCALL, errno = %d",
            SOCKERRNO);
      return -1;
    case SSL_ERROR_SSL:
      /*  A failure in the SSL library occurred, usually a protocol error.
          The OpenSSL error queue contains more information on the error. */
      sslerror = ERR_get_error();
      failf(conn->data, "SSL_write() error: %s",
            ERR_error_string(sslerror, error_buffer));
      return -1;
    }
    /* a true error */
    failf(conn->data, "SSL_write() return error %d", err);
    return -1;
  }
  return (ssize_t)rc; /* number of bytes */
}

/*
 * If the read would block we return -1 and set 'wouldblock' to TRUE.
 * Otherwise we return the amount of data read. Other errors should return -1
 * and set 'wouldblock' to FALSE.
 */
ssize_t Curl_ossl_recv(struct connectdata *conn, /* connection data */
                       int num,                  /* socketindex */
                       char *buf,                /* store read data here */
                       size_t buffersize,        /* max amount to read */