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https://issues.apache.org/jira/browse/SSHD-1215?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17423821#comment-17423821
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Roberto Deandrea commented on SSHD-1215:
----------------------------------------
Hi Thomas, implementing a junit test is a little bit tricky and requires time
because there are 3 parties involved, an SFTP client and two SFTP servers.
Anyway I made a little change to Apache SSHD code and it seems work fine
without EVIDENT bad effects.
We modified in +org.apache.sshd.sftp.server.FileHandle.java+ class the
following method :
_public void append(byte[] data, int doff, int length) throws IOException {_
_SeekableByteChannel channel = getFileChannel();_
_write(data, doff, length, *channel.size())*;_
_}_
with the following one:
_public void append(byte[] data, int doff, int length) throws IOException {_
_SeekableByteChannel channel = getFileChannel();_
_*long offset;*_
*_if(channel.size() > 0) {_*
*_offset = channel.size();_*
*_} else {_*
*_offset = channel.position();_*
*_}_*
*_write(data, doff, length, offset);_*
_}_
As I said, when WinSCP writea a *NEW* file to Apache SSHD server, it is opening
*ALWAYS* the file in *APPEND* mode (not in WRITE mode which should be the
defualt for a new file).
In this case *channel.size() is ALWAYS 0* because the file is *NEW*, and this
causes the +issue+ I reported, because SftpRemotePathChannel.write()/doWrite()
writes every chunk of file at offset 0!!!
I changed the code to handle this LIMIT CASE, i.e. appending to a new file
whose size is obviously 0.
If you append data on existing file whose size() is > 0, the code is working as
before.
What do you think about this code change ?
Is it correct according to you and can be reported in a next release of Apache
SSHD ?
Thanks in advance for your support
Roberto
> WinsCP transfer failure to Apache SSHD Server
> ---------------------------------------------
>
> Key: SSHD-1215
> URL: https://issues.apache.org/jira/browse/SSHD-1215
> Project: MINA SSHD
> Issue Type: Bug
> Affects Versions: 2.6.0
> Reporter: Roberto Deandrea
> Priority: Blocker
> Attachments: logs.zip
>
>
> Hi
> I have a failure transferring small files from a WinSCP SFTP client version
> 5.19.2 to a front-end Apache SSHD Server 2.6.0.
> The front-end Apache SSHD server is configured with a Filesystem built upon
> SFTPFileSystemProvider to proxy files to an Apache SSHD back-end server.
> WinSCP SFTP transfer files successfully directly to back-end Apache SSHD
> Server.
> I traced the SFTP file transfer on the front-end server and back-end server
> and it seems that something get wrong in the remote FileSystem set on the
> front-end server.
> From traces it seems that the first chunk of file is received correctly by
> the back-end server, but something is wrong on the second chuck of file
> transmitted.
> -------------------------------------------------------------------------------------------------------------------------
> First SSH_FXP_WRITE chunk received from front-end server :
> [16/09/21 09:18:26:364 CEST] 00000175 id=00000000
> org.apache.sshd.sftp.server.AbstractSftpSubsystemHelper 1 process
> process(ServerSessionImpl[allfuser1@/172.18.202.33:55400])[length=32757,
> type=SSH_FXP_WRITE, id=19718] processing
> [16/09/21 09:18:26:364 CEST] 00000175 id=00000000
> org.apache.sshd.sftp.server.SftpSubsystem 3 doWrite
> doWrite(ServerSessionImpl[allfuser1@/172.18.202.33:55400])[id=19718]
> *SSH_FXP_WRITE
> (handle=de6fcf635cb34b0e6d3d56643b7539a3[[/upload/rsa.key|https://issues.apache.org/upload/rsa.key]],
> offset=0, data=byte[32704])*
> First SSH_FXP_WRITE chunk sent by front-end SFTP client to back.end-server :
> [16/09/21 09:18:26:913 CEST] 00000175 id=00000000
> org.apache.sshd.sftp.client.impl.DefaultSftpClient 3 send
> send(SftpChannelSubsystem[id=0,
> recipient=0]-ClientSessionImpl[DMZ/172.18.202.33/allfuser1@/10.6.6.22:6471][sftp])
> cmd=SSH_FXP_WRITE, len=32752, id=139
> [16/09/21 09:18:27:010 CEST] 00000175 id=00000000
> org.apache.sshd.sftp.client.impl.AbstractSftpClient 3 checkResponseStatus
> checkResponseStatus(SftpChannelSubsystem[id=0,
> recipient=0]-ClientSessionImpl[DMZ/172.18.202.33/allfuser1@/10.6.6.22:6471][sftp])[id=139]
> cmd=SSH_FXP_WRITE status=SSH_FX_OK lang= msg=
>
> First SSH_FXP_WRITE chunk received succesfully from back-end server :
> [16/09/21 09:18:27:007 CEST] 00005c15 id=00000000
> org.apache.sshd.sftp.server.SftpSubsystem 3 doWrite
> doWrite(ServerSessionImpl[DMZ/172.18.202.33/allfuser1@/10.6.6.22:34445])[id=139]
> *SSH_FXP_WRITE
> (handle=c88cfd55dd514ccdd0428571191f5ea1[[/upload/rsa.key|https://issues.apache.org/upload/rsa.key]],
> offset=0, data=byte[32704])*
> [16/09/21 09:18:27:545 CEST] 00005c15 id=00000000
> org.apache.sshd.sftp.server.AbstractSftpSubsystemHelper 1 process
> process(ServerSessionImpl[DMZ/172.18.202.33/allfuser1@/10.6.6.22:34445])[length=32757,
>
> -----------------------------------------------------------------------------------------------------
> Second SSH_FXP_WRITE chunk received from front-end server:
> [16/09/21 09:18:27:012 CEST] 00000175 id=00000000
> org.apache.sshd.sftp.server.AbstractSftpSubsystemHelper 1 process
> process(ServerSessionImpl[allfuser1@/172.18.202.33:55400])[length=32757,
> type=SSH_FXP_WRITE, id=19974] processing
> [16/09/21 09:18:27:013 CEST] 00000175 id=00000000
> org.apache.sshd.sftp.server.SftpSubsystem 3 doWrite
> doWrite(ServerSessionImpl[allfuser1@/172.18.202.33:55400])[id=19974]
> *SSH_FXP_WRITE
> (handle=de6fcf635cb34b0e6d3d56643b7539a3[[/upload/rsa.key|https://issues.apache.org/upload/rsa.key]],
> offset=32704, data=byte[32704])*
>
> Second SSH_FXP_WRITE chunk sent by front-end SFTP client to back-end server:
> [16/09/21 09:18:27:473 CEST] 00000175 id=00000000
> org.apache.sshd.sftp.client.impl.DefaultSftpClient 3 send
> send(SftpChannelSubsystem[id=0,
> recipient=0]-ClientSessionImpl[DMZ/172.18.202.33/allfuser1@/10.6.6.22:6471][sftp])
> cmd=SSH_FXP_WRITE, len=32752, *id=141*
>
> Second SSH_FXP_WRITE chunk received from back-end server:
> type=SSH_FXP_WRITE, *id=141*] processing
> [16/09/21 09:18:27:545 CEST] 00005c15 id=00000000
> org.apache.sshd.sftp.server.SftpSubsystem 3 doWrite
> doWrite(ServerSessionImpl[DMZ/172.18.202.33/allfuser1@/10.6.6.22:34445])[*id=141*]
> SSH_FXP_WRITE
> (handle=c88cfd55dd514ccdd0428571191f5ea1[[/upload/rsa.key|https://issues.apache.org/upload/rsa.key]],
> *offset=0, data=byte[32704*])
> Now the back-end server complains about this data. The back-end server is
> expecting a chunk of data at offset=32704 and not offset = 0.
> java.io.IOException:
> position([/upload/rsa.key|https://issues.apache.org/upload/rsa.key]) *illegal
> file channel position, expected frsPosition: 32704, found: 0*
> This is a blocking error and causes the connection closing of the parts
> involved.
> ----------------------------------------------------------------------------------------------------------------------
> Full traces are attached to this jira.
>
> Questions and considerations.
> # Is this a known problem and is fixed in the latest release of Apache SSHD?
> # If this is a new problem can you suggest me how to fix it, or better
> troubleshoot it
> # Let me know if you need further info for troubleshooting
>
> Thanks in advance for your support
>
> Kind Regards
> Roberto Deandrea
>
>
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