InetAddress.getByName（“ 127.0.0.1。”）在Linux中引发错误，但在Windows中未引发

Question

I am expecting UnknownHostException when I call InetAddress.getByname("127.0.0.1.") due to extra dot in the end.

But it is not happening in windows, where as in Linux it is throwing error as expected.

Answer 1

This is a tricky one. I don't have an answer (yet), but here is what I have found.

UPDATE - I misread the code. Based on your comment there is a native method involved, and that means platform specific code.

I checked out the OpenJDK 8 code and took a look at the native method implementations:

jdk8u/jdk/src/{windows,solaris}/native/java/net/Inet4AddressImpl.c

The two versions of the code are very different, but in both cases, an attempt would be made to resolve a malformed IP address using the host C libraries. The difference in behaviour presumably lies in the C libraries. But you can check this all for yourself by looking at the relevant version of the OpenJDK codebase.

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Either way, the simple solution is probably to just fix the bad IP address. (I suppose, you could implement your own Java-side DNS service provider that specifically checked for malformed IP addresses before doing the DNS lookup, but it probably isn't worth the effort.)