[ipv6] RFR: 8223737: HostsFileNameService doesn't handle IPv6 literal addresses correctly
mark sheppard
macanaoire at hotmail.com
Tue May 14 11:14:06 UTC 2019
Hi Chris,
yes understood, thanks for that ... all good :+1 ... just wanted to highlight how the current mechanism worked
and
that on a Windows lapper there is a potential anomaly with the standard platform names service with the reverse lookup scenario.
regards
Mark
________________________________
From: Chris Hegarty <chris.hegarty at oracle.com>
Sent: Tuesday 14 May 2019 09:15
To: mark sheppard
Cc: Arthur Eubanks; OpenJDK Network Dev list
Subject: Re: [ipv6] RFR: 8223737: HostsFileNameService doesn't handle IPv6 literal addresses correctly
Mark,
The comparison by String was a reasonable choice when this mechanism was
added. What is being proposed here expands the functionality so that
logically equivalent IPv6 literals can be used without the need for
additional entries.
I did the following testing on my Linux box, Ubuntu 16.04, and it shows,
at least on this Linux flavour, that the platform name service operates
in a similar way to that of the change that is being proposed here.
$ cat /etc/*release*
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=16.04
DISTRIB_CODENAME=xenial
DISTRIB_DESCRIPTION="Ubuntu 16.04.5 LTS"
NAME="Ubuntu"
VERSION="16.04.5 LTS (Xenial Xerus)"
ID=ubuntu
ID_LIKE=debian
PRETTY_NAME="Ubuntu 16.04.5 LTS"
VERSION_ID="16.04"
HOME_URL="http://www.ubuntu.com/"
SUPPORT_URL="http://help.ubuntu.com/"
BUG_REPORT_URL="http://bugs.launchpad.net/ubuntu/"
VERSION_CODENAME=xenial
UBUNTU_CODENAME=xenial
$ uname -a
Linux chhegar 4.15.0-39-generic #42~16.04.1-Ubuntu SMP Wed Oct 24 17:09:54 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux
$
$
$ cat /etc/hosts
::3 xxyyzz
::1 localhost
::1 chhegar
# The following lines are desirable for IPv6 capable hosts
::1 ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters
$ ~/binaries/jdk-12/bin/jshell
| Welcome to JShell -- Version 12
| For an introduction type: /help intro
jshell> InetAddress.getByName("::3").getHostName()
$1 ==> "xxyyzz"
jshell> InetAddress.getByName("0:0:0:0:0:0:0:3").getHostName()
$2 ==> "xxyyzz"
jshell> InetAddress.getByName("0000:0000:0000:0000:0000:0000:0000:0003").getHostName()
$3 ==> "xxyyzz"
On 14 May 2019, at 00:52, mark sheppard <macanaoire at hotmail.com<mailto:macanaoire at hotmail.com>> wrote:
Hi Arthur, Chris,
just a note in passing, as you are well set on the changes, which is all good -- needs must, as they say.
The current implementation is an emulation of the gethostbyname and gethostbyaddr lookup on /etc/hosts.
The reverse lookup issue is also solved by adding an additional entry in the hosts file
0:0:0:0:0:0:0:1 ip6-localhost ip6-loopback. Your reverse lookup will pass.
$ /cygdrive/c/Development/jdk-installs/jdk-12/bin/java InternalNameServiceWithHostsFileTest
############################ InetAddress == ip6-localhost/0:0:0:0:0:0:0:1
retrieved address == [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1] equal to expected address == [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1]
testReverseLookup: host addr ::1 : expected host name ip6-localhost
testReverseLookup: host addr 0:0:0:0:0:0:0:1 : expected host name ip6-localhost
testReverseLookup: host addr 0000:0000:0000:0000:0000:0000:0000:0001 : expected host name ip6-localhost
That was the design -- the hosts file would contain whatever set of mapping are required for a particular context.
So the string comparison was sufficient.
IF your reverse lookup tests are run against the PlatformFormNameService,
which is the fall through to the native OS calls gethostbyname, getaddrinfo etc.
then you get the same set of failure afaik.
on windows using jdk12 test output shown below
so you could say there is some degree of consistent behaviour between the two services!!
regards
Mark
msheppard at MARKS-LAPTOP /cygdrive/c/Users/msheppard/eclipse-workspace/JDK-Tests
$ /cygdrive/c/Development/jdk-installs/jdk-12/bin/java -Djava.net.preferIPv6Addresses=true PlatformNameServiceTest
############################ InetAddress == localhost/0:0:0:0:0:0:0:1
retrieved address == [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1] equal to expected address == [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1]
testReverseLookup: host addr ::1 : expected host name localhost
Exception in thread "main" java.lang.RuntimeException: reverse lookup of "::1" is "0:0:0:0:0:0:0:1", should be "localhost"
at PlatformNameServiceTest.testReverseLookup(PlatformNameServiceTest.java:64)
at PlatformNameServiceTest.main(PlatformNameServiceTest.java:25)
msheppard at MARKS-LAPTOP /cygdrive/c/Users/msheppard/eclipse-workspace/JDK-Tests
$ /cygdrive/c/Development/jdk-installs/jdk-12/bin/java -Djava.net.preferIPv6Addresses=true PlatformNameServiceTest
############################ InetAddress == localhost/0:0:0:0:0:0:0:1
retrieved address == [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1] equal to expected address == [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1]
testReverseLookup: host addr 0:0:0:0:0:0:0:1 : expected host name localhost
Exception in thread "main" java.lang.RuntimeException: reverse lookup of "0:0:0:0:0:0:0:1" is "0:0:0:0:0:0:0:1", should be "localhost"
at PlatformNameServiceTest.testReverseLookup(PlatformNameServiceTest.java:64)
at PlatformNameServiceTest.main(PlatformNameServiceTest.java:26)
msheppard at MARKS-LAPTOP /cygdrive/c/Users/msheppard/eclipse-workspace/JDK-Tests
$ /cygdrive/c/Development/jdk-installs/jdk-12/bin/java -Djava.net.preferIPv6Addresses=true PlatformNameServiceTest
############################ InetAddress == localhost/0:0:0:0:0:0:0:1
retrieved address == [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1] equal to expected address == [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1]
testReverseLookup: host addr 0000:0000:0000:0000:0000:0000:0000:0001 : expected host name localhost
Exception in thread "main" java.lang.RuntimeException: reverse lookup of "0000:0000:0000:0000:0000:0000:0000:0001" is "0:0:0:0:0:0:0:1", should be "localhost"
at PlatformNameServiceTest.testReverseLookup(PlatformNameServiceTest.java:64)
at PlatformNameServiceTest.main(PlatformNameServiceTest.java:27)
________________________________
From: net-dev <net-dev-bounces at openjdk.java.net<mailto:net-dev-bounces at openjdk.java.net>> on behalf of Arthur Eubanks <aeubanks at google.com<mailto:aeubanks at google.com>>
Sent: Monday 13 May 2019 17:59
To: Chris Hegarty
Cc: OpenJDK Network Dev list
Subject: Re: [ipv6] RFR: 8223737: HostsFileNameService doesn't handle IPv6 literal addresses correctly
From: Chris Hegarty <chris.hegarty at oracle.com<mailto:chris.hegarty at oracle.com>>
Date: Mon, May 13, 2019 at 9:33 AM
To: Arthur Eubanks, OpenJDK Network Dev list
Arthur,
On 11/05/2019 01:17, Arthur Eubanks wrote:
> Bug: https://bugs.openjdk.java.net/browse/JDK-8223737
> Webrev: http://cr.openjdk.java.net/~aeubanks/8223737/webrev.00/index.html
>
> HostsFileNameService doesn't handle IPv6 literal addresses correctly.
> For example, ::1 and 0:0:0:0:0:0:0:1 should yield the same output.
>
> Rather than comparing address strings, compare the address byte arrays.
Comparison of byte arrays is much better. The changes look good.
Trivially, can I ask you to please include a number of other reverse
lookup's to fill out the test a little. Here's what I came up with:
testReverseLookup("10.2.3.4", "testHost.testDomain");
// ::1 and 0:0:0:0:0:0:0:1 should map to ip6-localhost
testReverseLookup("::1", "ip6-localhost");
testReverseLookup("0:0:0:0:0:0:0:1", "ip6-localhost");
testReverseLookup("0000:0000:0000:0000:0000:0000:0000:0001","ip6-localhost");
testReverseLookup("fe00::0", "ip6-localnet");
testReverseLookup("fe00:0:0:0:0:0:0:0", "ip6-localnet");
testReverseLookup("fe00:0000:0000:0000:0000:0000:0000:0000",
"ip6-localnet");
testReverseLookup("fe80::1", "link-local-host");
testReverseLookup("fe80:000:0:00:0:000:00:1", "link-local-host");
testReverseLookup("fe80:0000:0000:0000:0000:0000:0000:0001",
"link-local-host");
Thanks,
-Chris.
Added the extra reverse lookups.
I also noticed that the test is catching UnknownHostException and not rethrowing it, so I removed the try/catch.
Updated webrev: http://cr.openjdk.java.net/~aeubanks/8223737/webrev.01/index.html
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