Brandon,
The fix looks good to me. Thanks for contributing it.
- Michael.
On 15/12/11 23:14, Brandon Passanisi wrote:
Hello net-dev. I was wondering if somebody could review the
proposed fix for the following bug:
Bug URL: http://monaco.sfbay.sun.com/detail.jsf?cr=7078386
Webrev : http://cr.openjdk.java.net/~michaelm/7078386/webrev.1/
The bug is caused by an incorrect format string used in the fscanf
call within enumIPv6Interfaces of
jdk/src/solaris/native/java/net/NetworkInterface.c, which
specifies a two-digit hex number for the network interface index
value. It has been shown that network interface index values can
be more than 255, thus requiring the need to obtain more than two
digits. I eventually searched through the following linux kernel
source file:
linux-source-2.6.32/net/ipv6/addrconf.c
... and it appears the interface index value is being written and
an integer within the function inet6_fill_ifinfo in the following
block of code starting on line 3785:
if (dev->ifindex != dev->iflink)
NLA_PUT_U32(skb, IFLA_LINK, dev->iflink);
iflink is defined in linux-source-2.6.32/include/linux/netdevice.h
as an int on line 742:
/* Interface index. Unique device identifier */
int ifindex;
int iflink;
Because of this and because an integer is 32 bits, it appears that
updating the format string to use %08x for the interface index
value seems most correct.
I have tested out this fix successfully in the following ways:
1. I ran the IBM-supplied test programs tapadd and
Scope to create over 255 address in order to test an interface
index value of at least three digits. (These programs will be
added to the bug report if not present at this time.) The
tapadd program is a C test requiring root access that uses
tun/tap to create over 255 interfaces. Scope is a java program
that does a NetworkInterface.getByName() on a known interface
with an index over 255.
2. I modified the Scope program to additionally test all created
interfaces, not just one interface with an index value over
255. (The original Scope test program just checks a single
interface.) This is important to show there aren't regressions.
3. I created another test program using a script to run 'ip'
commands to create over 255 interfaces. This script runs in a
loop using the commands "sudo ip tunnel add..." and "sudo ip -6
addr add..." to add the interfaces. Then, I used the Scope
program to verify the created interfaces.
I wasn't able to create a script that would create a really huge
amount of interfaces because using numbers like 65536 or higher in
my script caused my Ubuntu linux to hang. So, I'm not quite sure
how to truly test large interface index values like 65536 or more.
Thanks.
--
Brandon Passanisi | Principle Member of
Technical Staff
 Oracle is committed
to developing practices and products that help protect the
environment
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