1 files changed, 16 insertions, 0 deletions
diff --git a/ext/openssl/lib/openssl/ssl.rb b/ext/openssl/lib/openssl/ssl.rb
index e1b557cd68..ed33f27f1d 100644
--- a/ext/openssl/lib/openssl/ssl.rb
+++ b/ext/openssl/lib/openssl/ssl.rb
@@ -252,6 +252,14 @@ module OpenSSL
       # This method MUST be called after calling #connect to ensure that the
       # hostname of a remote peer has been verified.
       def post_connection_check(hostname)
+        if peer_cert.nil?
+          msg = "Peer verification enabled, but no certificate received."
+          if using_anon_cipher?
+            msg += " Anonymous cipher suite #{cipher[0]} was negotiated. Anonymous suites must be disabled to use peer verification."
+          end
+          raise SSLError, msg
+        end
+
         unless OpenSSL::SSL.verify_certificate_identity(peer_cert, hostname)
           raise SSLError, "hostname \"#{hostname}\" does not match the server certificate"
         end
@@ -263,6 +271,14 @@ module OpenSSL
       rescue SSL::Session::SessionError
         nil
       end
+
+      private
+
+      def using_anon_cipher?
+        ctx = OpenSSL::SSL::SSLContext.new
+        ctx.ciphers = "aNULL"
+        ctx.ciphers.include?(cipher)
+      end
     end
 
     ##