So I have this situation: I try to download an image from somedomain.com using HTTPS. The domain is probably misconfigured, but unfortunately I can't change that. What exactly is happening:
When I browse to https://somedomain.com/animage.jpg I get a valid certificate issued for somedomain.com, which is perfect. But when I call the same site using it's IP address, say https://123.123.123.123 - I get a (also valid) certificate for *.hostingcompany.com - the certificate of the hosting company.
Now, I try to download the contents of the file using Java's HttpsUrlConnection, nothing special:
var urlConnection = new URL(imageUrl).openConnection();
((HttpURLConnection) urlConnection).getResponseCode();
(I want to first check the response code, but it's not important here.)
This code runs inside a Spring Boot App and is run on request. It works fine for the first request since booting the app. Each subsequent request fails with java.security.cert.CertificateException: No subject alternative DNS name matching somedomain.com found. It's because on each subsequent request the SSL Handshake is sent to the IP, not hostname, and get's the hosting company's certificate.
I was trying to find different settings for the SSL classes, but to no avail. I know there is a workaround where I could supply my own HostnameVerifier which could just return true, but that won't be secure, so I don't want to do that.
Did anyone encounter such problem? Maybe I'm searching in the wrong places? Maybe it's something with DNSes? I will appreciate any help.
Turns out it is a bug in Java 11.01. It is fixed since 11.02. After switching to 11.03. the behaviour I described above is gone. Each request gets a proper certificate.
Here are the details of the bug: https://bugs.openjdk.java.net/browse/JDK-8211806