RFR JDK-8239595/JDK-8239594 : ssl context version is not respected/jdk.tls.client.protocols is not respected

[Chris Hegarty]

Thank you Xuelei, this very helpful.

Sorry, but I am going to ask just a few more clarifying questions to make sure that we’re on the same page.

> On 27 Mar 2020, at 16:23, Xuelei Fan <xuelei.fan at oracle.com> wrote:
> 
> On 3/27/2020 5:52 AM, Chris Hegarty wrote:
>> Xuelei,
>> Before commenting further on the interaction of the HTTP Client with various contorted configurations, I would like to get a better understanding of the `jdk.tls.client.protocols` property.
>> Is there a specification or other documentation describing `jdk.tls.client.protocols` ?
> See the jdk.tls.client.protocols line in table 'Table 8-3 System Properties and Customized Items" in JSSE Reference Guides:
> 
> "https://docs.oracle.com/en/java/javase/14/security/java-secure-socket-extension-jsse-reference-guide.html#GUID-A41282C3-19A3-400A-A40F-86F4DA22ABA9
> 
> For your quick reference, I copied the note here:
> 
> ---------------
> Customized Item:
> Default handshaking protocols for TLS/DTLS clients.
> 
> Notes:
> To enable specific SunJSSE protocols on the client, specify them in a comma-separated list within quotation marks; all other supported protocols are not enabled on the client

“supported” here means protocols that are supported by the provider, and may be used within a specific context. This translates, for the default SSLContext, to the API call getSupportedSSLParameters().getProtocols(), right? 

getSupportedSSLParameters().getProtocols() returns a superset of getDefaultSSLParameters().getProtocols(). Conversely, getDefaultSSLParameters().getProtocols() is a strict subset of getSupportedSSLParameters().getProtocols(), right?

The `jdk.tls.client.protocols` property has no affect on getSupportedSSLParameters().getProtocols()  only getDefaultSSLParameters().getProtocols(), right? In which case, getDefaultSSLParameters().getProtocols() returns the value of  `jdk.tls.client.protocols`.

> For example,
> 
>    If jdk.tls.client.protocols="TLSv1,TLSv1.1", then the default protocol settings on the client for TLSv1 and TLSv1.1 are enabled, while SSLv3, TLSv1.2, TLSv1.3, and SSLv2Hello are not enabled
> 
>    If jdk.tls.client.protocols="DTLSv1.2" , then the protocol setting on the client for DTLS1.2 is enabled, while DTLS1.0 is not enabled
> ---------------

Seems that the term “client” here is referring to client-initiated exchanges, rather than any specific technology.

The assumption, which is reasonable, is that “clients” will use the default context. Again, this is reasonable default out-of-the-box behavior.

>> It is my understanding that the property only affects the *default* protocol’s ( not the supported protocols ) of the *default* context. That is, the context returned by `SSLContext.getInstance("Default”)`,
> It is correct that the property impact the default SSLContext only.  The default SSLContext instance could get from:
>    SSLContext.getInstance("Default");
>    SSLContext.getInstance("TLS");
>    SSLContext.getInstance("DTLS”);

Thanks for this clarification.

> 
>> and the protocol values returned by the following invocation on that context `getDefaultSSLParameters().getProtocols()`. Is this correct? If not, what does it do?
> Yes.

Thanks,
-Chris.