Do not request a client certificate as the default for SSL.

runtime/bin/secure_socket.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "bin/secure_socket.h"
 
 #include <errno.h>
 #include <fcntl.h>
 #include <sys/stat.h>
 #include <stdio.h>
@@ skipping 854 matching lines @@
   if (context == NULL) {
     DART_CHECK_VALID(Dart_ThrowException(DartUtils::NewDartArgumentError(
         "Default SecurityContext not implemented, context cannot be null.")));
   }
 
   ssl_ = SSL_new(context);
   SSL_set_bio(ssl_, ssl_side, ssl_side);
   SSL_set_mode(ssl_, SSL_MODE_AUTO_RETRY);  // TODO(whesse): Is this right?
   SSL_set_ex_data(ssl_, filter_ssl_index, this);
 
-  if (!is_server_) {
+  if (is_server_) {
+    // Do not request a client certificate.
+    // TODO(24069): Allow server to request a client certificate, when desired.
+    SSL_set_verify(ssl_, SSL_VERIFY_NONE, NULL);
+  } else {
     SetAlpnProtocolList(protocols_handle, ssl_, NULL, false);
     // Sets the hostname in the certificate-checking object, so it is checked
     // against the certificate presented by the server.
     X509_VERIFY_PARAM* certificate_checking_parameters_ = SSL_get0_param(ssl_);
     hostname_ = strdup(hostname);
     X509_VERIFY_PARAM_set_hostflags(certificate_checking_parameters_, 0);
     X509_VERIFY_PARAM_set1_host(certificate_checking_parameters_,
                                 hostname_, 0);
     // TODO(24186) free hostname_ if it is not freed when SSL is destroyed.
     // otherwise, make it a local variable, not a instance field.
   }
+  // Make the connection:
   if (is_server_) {
     status = SSL_accept(ssl_);
     if (SSL_LOG_STATUS) Log::Print("SSL_accept status: %d\n", status);
     if (status != 1) {
       // TODO(whesse): expect a needs-data error here.  Handle other errors.
       error = SSL_get_error(ssl_, status);
       if (SSL_LOG_STATUS) Log::Print("SSL_accept error: %d\n", error);
     }
   } else {
     status = SSL_connect(ssl_);
@@ skipping 201 matching lines @@
     } else {
       if (SSL_LOG_DATA) Log::Print(
           "WriteEncrypted  BIO_read wrote %d bytes\n", bytes_processed);
     }
   }
   return bytes_processed;
 }
 
 }  // namespace bin
 }  // namespace dart