RFR: 8376031: HttpsURLConnection.getServerCertificates() throws "java.lang.IllegalStateException: connection not yet open" for the HEAD method

[Jaikiran Pai]

On Thu, 29 Jan 2026 15:32:50 GMT, Daniel Fuchs <dfuchs at openjdk.org> wrote:

> The issue here is that `HttpURLConnection` is automatically disconnected (`HttpClient` is set to `null`, `connected` is set to `false`) when a response with no response body bytes is received. This happens before a fake empty body input stream is returned to the user. That behaviour also occurs with any method for which `content-length: 0` is returned (GET, POST, custom, anything), and with any status code (204, 304) for which there is no body.
> 
> In this case, the proposed fix is to store the `SSLSession` in the `AbstractDelegateHttpsURLConnection` subclass until such a time where `disconnect()` is explicitely closed. Information pertaining to SSL, such as server certificates, can be extracted from the saved `SSLSession`.

test/jdk/sun/net/www/protocol/https/HttpsURLConnection/GetServerCertificates.java line 229:

> 227:     // HTTP Server
> 228:     HttpServer startHttpServer() throws IOException {
> 229:         InetAddress localhost = InetAddress.getLocalHost();

I am guessing that the use of localhost instead of loopback is an oversight?

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PR Review Comment: https://git.openjdk.org/jdk/pull/29489#discussion_r2751122453