Please review this PR to use modern APIs and language features to simplify
`equals` and `hashCode` in security area.
I understand that security area is sensitive and a non-expert, such as myself,
should tread carefully; so below are my notes to assist the review.
* Unlike `hashCode`, non-secure `equals` implementations are typically
short-circuit. But because of "timing attacks", we seem to have specialized
implementations, such as `java.security.MessageDigest.isEqual(byte[], byte[])`
and a more general `sun.security.util.ByteArrays.isEqual(byte[], int, int,
byte[], int, int)`. So while reviewing this PR, take an opportunity to audit
the affected `equals` implementations: perhaps some of them need to become
secure, not modern. I have no domain knowledge to tell those cases apart, I
only note that those cases exist.
* This PR sacrifices compatibility for pragmatism: it changes some `hashCode`
implementations to produce different values than before to allow more
utilization of methods from `Objects` and `Arrays`. To my mind, those changes
are **benign**. If you disagree, I'd be happy to discuss that and/or retract
the concerning part of the change.
* BitArray could be a topic of its own, but I'll do my best to be concise.
* Truth to be told, BitArray's `equals` and `hashCode` are not used
anywhere in source, and `equals` is only used in one test. For that reason, I
refrained from reimplementing internals of `BitArray` using more general
`java.util.BitSet`: too much effort and risk for almost nothing.
* Speaking of `BitSet`-powered `BitArray`. Such an implementation is not
for the faint of heart: there's too much impedance mismatch between data
structures that those classes use to store bits. That said, for the sake of
testing that it is possible and that I understand the `BitArray` correctly, I
actually implemented it using `BitSet`. While that implementation is **NOT**
part of this PR, you can have a look at it
[here](https://cr.openjdk.org/~prappo/8311170/BitArray.java).
* One suggestion to consider is to change this somewhat arcane piece in
java.security.UnresolvedPermission.equals:
// check certs
if (this.certs == null && that.certs != null ||
this.certs != null && that.certs == null ||
this.certs != null &&
this.certs.length != that.certs.length) {
return false;
}
int i,j;
boolean match;
for (i = 0; this.certs != null && i < this.certs.length; i++) {
match = false;
for (j = 0; j < that.certs.length; j++) {
if (this.certs[i].equals(that.certs[j])) {
match = true;
break;
}
}
if (!match) return false;
}
for (i = 0; that.certs != null && i < that.certs.length; i++) {
match = false;
for (j = 0; j < this.certs.length; j++) {
if (that.certs[i].equals(this.certs[j])) {
match = true;
break;
}
}
if (!match) return false;
}
return true;
to this:
// check certs
if (this.certs == null && that.certs != null ||
this.certs != null && that.certs == null)
return false;
if (this.certs == null) {
assert that.certs == null;
return false;
}
return Set.of(this.certs).equals(Set.of(that.certs));
-------------
Commit messages:
- Initial commit
Changes: https://git.openjdk.org/jdk/pull/14738/files
Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=14738&range=00
Issue: https://bugs.openjdk.org/browse/JDK-8311170
Stats: 127 lines in 6 files changed: 16 ins; 73 del; 38 mod
Patch: https://git.openjdk.org/jdk/pull/14738.diff
Fetch: git fetch https://git.openjdk.org/jdk.git pull/14738/head:pull/14738
PR: https://git.openjdk.org/jdk/pull/14738
