RFR: 8209137: Add ability to bind to specific local address to HTTP client

[Daniel Fuchs]

On Fri, 3 Dec 2021 06:15:31 GMT, Jaikiran Pai <jpai at openjdk.org> wrote:

> This change proposes to implement the enhancement noted in https://bugs.openjdk.java.net/browse/JDK-8209137.
> 
> The change introduces a new API to allow applications to build a `java.net.http.HTTPClient` configured with a specific local address that will be used while creating `Socket`(s) for connections.

Generally it would be good if the test did not make any assumption on the presence - or absence - of either IPv4 or IPv6 on the tested machine.
The IPSupport test library class has methods that allows a test to inquire whether IPv6 or IPv4 are available - I would recommend using them to figure out which test cases can be tested on the machine the test runs on.

test/jdk/java/net/httpclient/HttpClientLocalAddrTest.java line 74:

> 72: 
> 73:     @BeforeClass
> 74:     public static void beforeClass() throws Exception {

For HttpClient tests - unless they are specific to HTTP/1.1 I'd recommend making the test class implement HttpServerAdapters and test will all versions of the protocol (http, https, http/2, and https/2).
An example can be found in e.g. `test/jdk/java/net/httpclient/CancelRequestTest.java`

test/jdk/java/net/httpclient/HttpClientLocalAddrTest.java line 205:

> 203:             // anyAddress
> 204:             if (Boolean.getBoolean("java.net.preferIPv6Addresses")) {
> 205:                 // ipv6 wildcard

::1 is the ipv6 loopback - not the ipv6 wildcard

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PR: https://git.openjdk.java.net/jdk/pull/6690