[jira] [Created] (SSHD-1288) Infinite loop in org.apache.sshd.sftp.client.impl.SftpInputStreamAsync#doRead

["Ivan Fiorentini (Jira)" <ji...@apache.org>]

Ivan Fiorentini created SSHD-1288:
-------------------------------------

             Summary: Infinite loop in org.apache.sshd.sftp.client.impl.SftpInputStreamAsync#doRead
                 Key: SSHD-1288
                 URL: https://issues.apache.org/jira/browse/SSHD-1288
             Project: MINA SSHD
          Issue Type: Bug
    Affects Versions: 2.8.0
            Reporter: Ivan Fiorentini
         Attachments: image-2022-08-05-17-08-55-698.png

I reported an  infinite loop  in org.apache.sshd.sftp.client.impl.SftpInputStreamAsync#doRead:

and after the production of a thread and system dump the  point in execution was:


{code:java}
private long doRead(long max, BufferConsumer consumer) throws IOException {
    long orgOffset = clientOffset;
    while (max > 0) {
        if (hasNoData()) {
            if (eofIndicator) {
                break;
            }
            if (!pendingReads.isEmpty()) {
                fillData();
            }
            if (!eofIndicator) {
                sendRequests(); <- (do not send any request ! it does nothing !)
            }
        } else {
            int nb = (int) Math.min(max, buffer.available());
            consumer.consume(new ByteArrayBuffer(buffer.array(), buffer.rpos(), nb));
            buffer.rpos(buffer.rpos() + nb);
            clientOffset += nb;
            max -= nb;
        }
    }
    return clientOffset - orgOffset;
}
{code}
 
In the system dump it seems the size of file to receive  is obtained before to start the transfer... this size is 82.132.992 bytes; but during the receipt of the data it seems (at the time of the dump) that 82.156.760 was successfully received... *_this could happen if , during the file receipt, at the remote site the file is written (expanded) with more data._*

... but when the size of the received data is greater than the original it seems an infinite loop could happen in the org.apache.sshd.sftp.client.impl.SftpInputStreamAsync#doRead when the sendRequests() is invoked to obtain more data (or receive the end of file);

In the sendRequest():
{code:java}
while (pendingReads.size() < Math.max(1, windowSize / bufferSize)
       && (fileSize <= 0 || requestOffset < fileSize + bufferSize)) {
       
       ... do the send request to obtain more data (or to receive the end of file)      
        requestOffset += bufferSize;
        }
{code}
 ... the condition *requestOffset < fileSize + bufferSize* 
is not satisfied if the *requestOffset* >= *fileSize + bufferSize*
preventing the code from sending a request to receive more data (and/or obtain the end of file) and causing the infinite loop.

The values of the above variables at time of the dump was:
!image-2022-08-05-17-08-55-698.png!


... so that "{*}(fileSize <= 0 || requestOffset < fileSize + bufferSize)"{*} is {color:#de350b}*FALSE*{color}

To reproduce the problem:
 # create the remote file to receive (1Mb size)
 # create SftpClient sftp = DefaultSftpClientFactory.NSTANCE.createSftpClient(clientSession)
 # create InputStream is = sftp.read(file, 32768) end read the inputstrem 4kb at time
 # stop at the end of while loop block in org.apache.sshd.sftp.client.impl.SftpInputStreamAsync#sendRequests
when the requestOffset > fileSize
 # expand the remote file size to 2Mb
 # remove the stop at point 4 and continue
 # {color:#ffbdad}the code enter into an infinite loop{color}



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