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https://issues.apache.org/jira/browse/HADOOP-12345?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15353974#comment-15353974
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Andrew Wang commented on HADOOP-12345:
--------------------------------------
Looked at the PR. Can we add a test for the length % 4 == 0 case? I think the
current code is not quite right:
{code}
+ int padding = 0;
+ // we do not need compute padding if the hostname is already a multiple of
4
+ if (mHostName.getBytes(Charsets.UTF_8).length != 0) {
+ padding = 4 - (mHostName.getBytes(Charsets.UTF_8).length % 4);
+ }
{code}
I think you meant to check that the len % 4 != 0. I think it'd be even better
though if we just {{%4}} the padding one more time, saves the if statement.
Also we only need that comment about the padding once, can delete the second
one.
> Credential length in CredentialsSys.java incorrect
> --------------------------------------------------
>
> Key: HADOOP-12345
> URL: https://issues.apache.org/jira/browse/HADOOP-12345
> Project: Hadoop Common
> Issue Type: Bug
> Components: nfs
> Affects Versions: 2.6.0, 2.7.0
> Reporter: Pradeep Nayak Udupi Kadbet
> Priority: Critical
> Attachments: HADOOP-12345.patch
>
>
> Hi -
> There is a bug in the way hadoop-nfs sets the credential length in
> "Credentials" field of the NFS RPC packet when using AUTH_SYS
> In CredentialsSys.java, when we are writing the creds in to XDR object, we
> set the length as follows:
> // mStamp + mHostName.length + mHostName + mUID + mGID + mAuxGIDs.count
> 96 mCredentialsLength = 20 + mHostName.getBytes().length;
> (20 corresponds to 4 bytes for mStamp, 4 bytes for mUID, 4 bytes for mGID, 4
> bytes for length field of hostname, 4 bytes for number of aux 4 gids) and
> this is okay.
> However when we add the length of the hostname to this, we are not adding the
> extra padded bytes for the hostname (If the length is not a multiple of 4)
> and thus when the NFS server reads the packet, it returns GARBAGE_ARGS
> because it doesn't read the uid field when it is expected to read. I can
> reproduce this issue constantly on machines where the hostname length is not
> a multiple of 4.
> A possible fix is to do something this:
> int pad = mHostName.getBytes().length % 4;
> // mStamp + mHostName.length + mHostName + mUID + mGID + mAuxGIDs.count
> mCredentialsLength = 20 + mHostName.getBytes().length + pad;
> I would be happy to submit the patch but I need some help to commit into
> mainline. I haven't committed into Hadoop yet.
> Cheers!
> Pradeep
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