GabriRuflex commented on issue #275:
URL: https://github.com/apache/mina-sshd/issues/275#issuecomment-1325329363
Hi Tomas and thanks for your support!
> What does the _remote_ device run?
SSH 2.0, unfortunately no more details :(
> Three points:
>
> 1. The exception occurs after having received an error reply from the
server in response to the `sftp.open()` call. So even if this particular
exception is fixed, your problem will not be solved.
I tried also to mount the remote filesystem but it's still not working (only
in that specific device)
```
...
SftpFileSystemProvider provider = new SftpFileSystemProvider(client);
try (FileSystem fs = provider.newFileSystem(session)) {
Path remotePath = fs.getPath(remotefilepath);
try {
Files.copy(localfileStream, remotePath,
StandardCopyOption.REPLACE_EXISTING);
} catch (IOException e) {}
}
...
```
```
org.apache.sshd.common.util.buffer.BufferException: Underflow: requested=4,
available=0
at
deployment.test.ear//org.apache.sshd.common.util.buffer.Buffer.ensureAvailable(Buffer.java:635)
at
deployment.test.ear//org.apache.sshd.common.util.buffer.Buffer.getUInt(Buffer.java:281)
at
deployment.test.ear//org.apache.sshd.common.util.buffer.Buffer.getInt(Buffer.java:277)
at
deployment.test.ear//org.apache.sshd.common.util.buffer.ByteArrayBuffer.getString(ByteArrayBuffer.java:240)
at
deployment.test.ear//org.apache.sshd.common.util.buffer.Buffer.getString(Buffer.java:309)
at
deployment.test.ear//org.apache.sshd.sftp.client.impl.AbstractSftpClient.checkAttributesResponse(AbstractSftpClient.java:298)
at
deployment.test.ear//org.apache.sshd.sftp.client.impl.AbstractSftpClient.checkAttributes(AbstractSftpClient.java:283)
at
deployment.test.ear//org.apache.sshd.sftp.client.impl.AbstractSftpClient.stat(AbstractSftpClient.java:997)
at
deployment.test.ear//org.apache.sshd.sftp.client.fs.SftpFileSystem$Wrapper.stat(SftpFileSystem.java:412)
at
deployment.test.ear//org.apache.sshd.sftp.client.fs.SftpFileSystemProvider.resolveRemoteFileAttributes(SftpFileSystemProvider.java:981)
at
deployment.test.ear//org.apache.sshd.sftp.client.fs.SftpFileSystemProvider.lambda$readRemoteAttributes$0(SftpFileSystemProvider.java:969)
at
deployment.test.ear//org.apache.sshd.sftp.client.impl.SftpPathImpl.withAttributeCache(SftpPathImpl.java:120)
at
deployment.test.ear//org.apache.sshd.sftp.client.impl.SftpPathImpl.withAttributeCache(SftpPathImpl.java:140)
at
deployment.test.ear//org.apache.sshd.sftp.client.fs.SftpFileSystemProvider.readRemoteAttributes(SftpFileSystemProvider.java:969)
at
deployment.test.ear//org.apache.sshd.sftp.client.impl.AbstractSftpFileAttributeView.readRemoteAttributes(AbstractSftpFileAttributeView.java:71)
at
deployment.test.ear//org.apache.sshd.sftp.client.fs.SftpPosixFileAttributeView.readAttributes(SftpPosixFileAttributeView.java:52)
at
deployment.test.ear//org.apache.sshd.sftp.client.fs.SftpPosixFileAttributeView.readAttributes(SftpPosixFileAttributeView.java:40)
at
deployment.test.ear//org.apache.sshd.sftp.client.fs.SftpFileSystemProvider.checkAccess(SftpFileSystemProvider.java:826)
at
deployment.test.ear//org.apache.sshd.sftp.client.fs.SftpFileSystemProvider.delete(SftpFileSystemProvider.java:581)
at
java.base/java.nio.file.spi.FileSystemProvider.deleteIfExists(FileSystemProvider.java:787)
at java.base/java.nio.file.Files.deleteIfExists(Files.java:1181)
at java.base/java.nio.file.Files.copy(Files.java:3055)
at
deployment.test.ear//com.test.UploadFile.upload(UploadFile.java:109)
```
> 2. The `BufferException: Underflow: requested=4, available=0` [at that
point](https://github.com/apache/mina-sshd/blob/45fd3a4a84c453a5e053cce624f63465844deb07/sshd-sftp/src/main/java/org/apache/sshd/sftp/client/impl/AbstractSftpClient.java#L248)
indicates that the server sent no error message or language tag in the error
status reply. I can't find any information that would say these were
optional... but Apache MINA sshd could perhaps be lenient and consider them so.
I can login to that device via CLI using `ssh` or `sftp` tools. Also other
java libraries can do that.
> 3. The failing code has been touched last 8 years ago, so the problem
is certainly not new in 2.9.2. I wonder why this problem never was reported
before? Probably the remote device runs a very old version of SFTP. [Prior to
SFTP version
3](https://datatracker.ietf.org/doc/html/draft-ietf-secsh-filexfer-09#section-12.4),
the SSH_FXP_STATUS reply indeed didn't have the error message and language tag
fields.
I'm trying to migrate from another java library (which is working properly)
to Apache MINA sshd so I don't know if this issue is new or it a regression
related to the latest version
On the old library I just added a try catch to ignore the SSH_FXP_STATUS
error and go ahead with the execution.
The current SFTP version is 3
```
sftp> version
SFTP protocol version 3
```
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