Koji Kawamura created NIFI-4040:
-----------------------------------
Summary: ListSFTP fails to retrieve user home directory for
certain user accounts
Key: NIFI-4040
URL: https://issues.apache.org/jira/browse/NIFI-4040
Project: Apache NiFi
Issue Type: Bug
Components: Extensions
Reporter: Koji Kawamura
Assignee: Koji Kawamura
For some reason, when ListSFTP tries to get users home directory using
com.jcraft.jsch.ChannelSftp.getHome() method, it fails with following error
with certain user accounts:
{code}
2017-04-05 11:33:37,645 ERROR [Timer-Driven Process Thread-20]
o.a.nifi.processors.standard.ListSFTP
java.io.IOException: Failed to obtain connection to remote host due to 2: File
not found
at
org.apache.nifi.processors.standard.util.SFTPTransfer.getChannel(SFTPTransfer.java:447)
...
Caused by: com.jcraft.jsch.SftpException: File not found
at com.jcraft.jsch.ChannelSftp.throwStatusError(ChannelSftp.java:2873)
~[jsch-0.1.54.jar:na]
at com.jcraft.jsch.ChannelSftp._realpath(ChannelSftp.java:2367)
~[jsch-0.1.54.jar:na]
at com.jcraft.jsch.ChannelSftp.getHome(ChannelSftp.java:2437)
~[jsch-0.1.54.jar:na]
at
org.apache.nifi.processors.standard.util.SFTPTransfer.getChannel(SFTPTransfer.java:443)
~[nifi-standard-processors-1.1.0.2.1.1.0-2.jar:1.1.0.2.1.1.0-2]
{code}
This happens when the library sends SSH_FXP_REALPATH(16) with an empty string.
Server returned SSH_FXP_STATUS(101). According [SSH File Transfer
Protocol|https://tools.ietf.org/id/draft-ietf-secsh-filexfer-13.txt]
specification, 101 means:
{quote}
The server MUST respond with SSH_FXP_STATUS(SSH_FX_OP_UNSUPPORTED) if it
receives a packet it does not recognize.
{quote}
So, it indicates that client library sends a request packet that the server
didn't understand. Since this error happens with certain user account, based on
their home directly, there might be a combination that causes this issue.
Although those user accounts fail with getHome method, they can list files if
we don't call getHome(). (Confirmed by commenting out the getHome call)
The home directory is used to address a relative 'Remote Path' to a full path
by PutSFTP and PutFTP. The fullpath is only used for 'Transit URI' for their
SEND provenance event.
Summary:
* There is no way to alter getHome method behavior from NiFi code base
* Without getHome those user accounts can list the problematic FTP server
* The value retrieved by getHome is only used for provenance event and it works
without it
>From above observations, I propose to wrap getHome call with try/catch clause,
>and if it fails just log some message then continue.
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