[
https://issues.apache.org/jira/browse/SSHD-1147?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Alex D updated SSHD-1147:
-------------------------
Description:
Some propretory SFTP servers support a so-called "one time download" policy
also known as Extractability Count.
Current implementation of the input stream based read ofile operation
org.apache.sshd.client.subsystem.sftp.SftpClient::read(String path) uses
org.apache.sshd.client.subsystem.sftp.impl.SftpInputStreamAsync
which performs 2 operations in its constructor:
1) Open remote file (SftpClient::open)
2) Calculate remote file size using file's handle obtained in 1)
As a result the following error is produced on attempt to download a file from
IBMs SFTP:
SFTP error (SSH_FX_FAILURE): The message [remote file path] is not extractable!
IBM specifically states that it's not their problem at all, and they are not
going to fix it.
According to their flow described here:
https://www.ibm.com/support/pages/node/1121475?lang=en
"Any attempt from client to issue other SFTP operations like SSH_FXP_STAT
(reading attributes) makes server to validate extractability_count > 0.
If found 0, download would be reported as "not extractable".
Most likely it's possible to use SftpClient::openRemoteFileChannel and work
with the obtained FileChannel manually without any additional requests to stat
remote file size.
Though it would be a cumbersome approach, as reading remote file in chunks not
knowing its size in this case will be far from optimal.
was:
Some propretory SFTP servers support a so-called "one time download" policy
also known as Extractability Count.
Current implementation of the input stream based read ofile operation
[org|eclipse-javadoc:%E2%98%82=nt-common/%5C/home%5C/ghost%5C/.m2%5C/repository%5C/org%5C/apache%5C/sshd%5C/sshd-sftp%5C/2.5.1%5C/sshd-sftp-2.5.1.jar=/maven.pomderived=/true=/=/maven.pomderived=/true=/=/maven.groupId=/org.apache.sshd=/=/maven.artifactId=/sshd-sftp=/=/maven.version=/2.5.1=/=/maven.scope=/compile=/%3Corg]{color:#000000}.{color}[apache|eclipse-javadoc:%E2%98%82=nt-common/%5C/home%5C/ghost%5C/.m2%5C/repository%5C/org%5C/apache%5C/sshd%5C/sshd-sftp%5C/2.5.1%5C/sshd-sftp-2.5.1.jar=/maven.pomderived=/true=/=/maven.pomderived=/true=/=/maven.groupId=/org.apache.sshd=/=/maven.artifactId=/sshd-sftp=/=/maven.version=/2.5.1=/=/maven.scope=/compile=/%3Corg.apache]{color:#000000}.{color}[sshd|eclipse-javadoc:%E2%98%82=nt-common/%5C/home%5C/ghost%5C/.m2%5C/repository%5C/org%5C/apache%5C/sshd%5C/sshd-sftp%5C/2.5.1%5C/sshd-sftp-2.5.1.jar=/maven.pomderived=/true=/=/maven.pomderived=/true=/=/maven.groupId=/org.apache.sshd=/=/maven.artifactId=/sshd-sftp=/=/maven.version=/2.5.1=/=/maven.scope=/compile=/%3Corg.apache.sshd]{color:#000000}.{color}[client|eclipse-javadoc:%E2%98%82=nt-common/%5C/home%5C/ghost%5C/.m2%5C/repository%5C/org%5C/apache%5C/sshd%5C/sshd-sftp%5C/2.5.1%5C/sshd-sftp-2.5.1.jar=/maven.pomderived=/true=/=/maven.pomderived=/true=/=/maven.groupId=/org.apache.sshd=/=/maven.artifactId=/sshd-sftp=/=/maven.version=/2.5.1=/=/maven.scope=/compile=/%3Corg.apache.sshd.client]{color:#000000}.{color}[subsystem|eclipse-javadoc:%E2%98%82=nt-common/%5C/home%5C/ghost%5C/.m2%5C/repository%5C/org%5C/apache%5C/sshd%5C/sshd-sftp%5C/2.5.1%5C/sshd-sftp-2.5.1.jar=/maven.pomderived=/true=/=/maven.pomderived=/true=/=/maven.groupId=/org.apache.sshd=/=/maven.artifactId=/sshd-sftp=/=/maven.version=/2.5.1=/=/maven.scope=/compile=/%3Corg.apache.sshd.client.subsystem]{color:#000000}.{color}[sftp|eclipse-javadoc:%E2%98%82=nt-common/%5C/home%5C/ghost%5C/.m2%5C/repository%5C/org%5C/apache%5C/sshd%5C/sshd-sftp%5C/2.5.1%5C/sshd-sftp-2.5.1.jar=/maven.pomderived=/true=/=/maven.pomderived=/true=/=/maven.groupId=/org.apache.sshd=/=/maven.artifactId=/sshd-sftp=/=/maven.version=/2.5.1=/=/maven.scope=/compile=/%3Corg.apache.sshd.client.subsystem.sftp]{color:#000000}.SftpClient{color}::read(String
path) uses
[org|eclipse-javadoc:%E2%98%82=nt-common/%5C/home%5C/ghost%5C/.m2%5C/repository%5C/org%5C/apache%5C/sshd%5C/sshd-sftp%5C/2.5.1%5C/sshd-sftp-2.5.1.jar=/maven.pomderived=/true=/=/maven.pomderived=/true=/=/maven.groupId=/org.apache.sshd=/=/maven.artifactId=/sshd-sftp=/=/maven.version=/2.5.1=/=/maven.scope=/compile=/%3Corg]{color:#000000}.{color}[apache|eclipse-javadoc:%E2%98%82=nt-common/%5C/home%5C/ghost%5C/.m2%5C/repository%5C/org%5C/apache%5C/sshd%5C/sshd-sftp%5C/2.5.1%5C/sshd-sftp-2.5.1.jar=/maven.pomderived=/true=/=/maven.pomderived=/true=/=/maven.groupId=/org.apache.sshd=/=/maven.artifactId=/sshd-sftp=/=/maven.version=/2.5.1=/=/maven.scope=/compile=/%3Corg.apache]{color:#000000}.{color}[sshd|eclipse-javadoc:%E2%98%82=nt-common/%5C/home%5C/ghost%5C/.m2%5C/repository%5C/org%5C/apache%5C/sshd%5C/sshd-sftp%5C/2.5.1%5C/sshd-sftp-2.5.1.jar=/maven.pomderived=/true=/=/maven.pomderived=/true=/=/maven.groupId=/org.apache.sshd=/=/maven.artifactId=/sshd-sftp=/=/maven.version=/2.5.1=/=/maven.scope=/compile=/%3Corg.apache.sshd]{color:#000000}.{color}[client|eclipse-javadoc:%E2%98%82=nt-common/%5C/home%5C/ghost%5C/.m2%5C/repository%5C/org%5C/apache%5C/sshd%5C/sshd-sftp%5C/2.5.1%5C/sshd-sftp-2.5.1.jar=/maven.pomderived=/true=/=/maven.pomderived=/true=/=/maven.groupId=/org.apache.sshd=/=/maven.artifactId=/sshd-sftp=/=/maven.version=/2.5.1=/=/maven.scope=/compile=/%3Corg.apache.sshd.client]{color:#000000}.{color}[subsystem|eclipse-javadoc:%E2%98%82=nt-common/%5C/home%5C/ghost%5C/.m2%5C/repository%5C/org%5C/apache%5C/sshd%5C/sshd-sftp%5C/2.5.1%5C/sshd-sftp-2.5.1.jar=/maven.pomderived=/true=/=/maven.pomderived=/true=/=/maven.groupId=/org.apache.sshd=/=/maven.artifactId=/sshd-sftp=/=/maven.version=/2.5.1=/=/maven.scope=/compile=/%3Corg.apache.sshd.client.subsystem]{color:#000000}.{color}[sftp|eclipse-javadoc:%E2%98%82=nt-common/%5C/home%5C/ghost%5C/.m2%5C/repository%5C/org%5C/apache%5C/sshd%5C/sshd-sftp%5C/2.5.1%5C/sshd-sftp-2.5.1.jar=/maven.pomderived=/true=/=/maven.pomderived=/true=/=/maven.groupId=/org.apache.sshd=/=/maven.artifactId=/sshd-sftp=/=/maven.version=/2.5.1=/=/maven.scope=/compile=/%3Corg.apache.sshd.client.subsystem.sftp]{color:#000000}.{color}[impl|eclipse-javadoc:%E2%98%82=nt-common/%5C/home%5C/ghost%5C/.m2%5C/repository%5C/org%5C/apache%5C/sshd%5C/sshd-sftp%5C/2.5.1%5C/sshd-sftp-2.5.1.jar=/maven.pomderived=/true=/=/maven.pomderived=/true=/=/maven.groupId=/org.apache.sshd=/=/maven.artifactId=/sshd-sftp=/=/maven.version=/2.5.1=/=/maven.scope=/compile=/%3Corg.apache.sshd.client.subsystem.sftp.impl]{color:#000000}.{color}[SftpInputStreamAsync|eclipse-javadoc:%E2%98%82=nt-common/%5C/home%5C/ghost%5C/.m2%5C/repository%5C/org%5C/apache%5C/sshd%5C/sshd-sftp%5C/2.5.1%5C/sshd-sftp-2.5.1.jar=/maven.pomderived=/true=/=/maven.pomderived=/true=/=/maven.groupId=/org.apache.sshd=/=/maven.artifactId=/sshd-sftp=/=/maven.version=/2.5.1=/=/maven.scope=/compile=/%3Corg.apache.sshd.client.subsystem.sftp.impl(SftpInputStreamAsync.class%E2%98%83SftpInputStreamAsync]
which performs 2 operations in its constructor:
1) Open remote file (SftpClient::open)
2) Calculate remote file size using file's handle obtained in 1)
As a result the following error is produced on attempt to download a file from
IBMs SFTP:
SFTP error (SSH_FX_FAILURE): The message [remote file path] is not extractable!
IBM specifically states that it's not their problem at all, and they are not
going to fix it.
According to their flow described here:
[https://www.ibm.com/support/pages/node/1121475?lang=en]
"Any attempt from client to issue other SFTP operations like SSH_FXP_STAT
(reading attributes) makes server to validate extractability_count > 0.
If found 0, download would be reported as "not extractable".
Most likely it's possible to use SftpClient::openRemoteFileChannel and work
with the obtained FileChannel manually without any additional requests to stat
remote file size (not yet verified/confirmed).
Though it would be a cumbersome approach, as reading remote file in chunks not
knowing its size in this case will be far from optimal.
> SftpClient is not able to download file from proprietory SFTP servers (IBM)
> with a one time download policy
> -----------------------------------------------------------------------------------------------------------
>
> Key: SSHD-1147
> URL: https://issues.apache.org/jira/browse/SSHD-1147
> Project: MINA SSHD
> Issue Type: Wish
> Affects Versions: 2.5.1
> Reporter: Alex D
> Priority: Major
>
> Some propretory SFTP servers support a so-called "one time download" policy
> also known as Extractability Count.
> Current implementation of the input stream based read ofile operation
> org.apache.sshd.client.subsystem.sftp.SftpClient::read(String path) uses
> org.apache.sshd.client.subsystem.sftp.impl.SftpInputStreamAsync
> which performs 2 operations in its constructor:
> 1) Open remote file (SftpClient::open)
> 2) Calculate remote file size using file's handle obtained in 1)
> As a result the following error is produced on attempt to download a file
> from IBMs SFTP:
> SFTP error (SSH_FX_FAILURE): The message [remote file path] is not
> extractable!
> IBM specifically states that it's not their problem at all, and they are not
> going to fix it.
> According to their flow described here:
> https://www.ibm.com/support/pages/node/1121475?lang=en
> "Any attempt from client to issue other SFTP operations like SSH_FXP_STAT
> (reading attributes) makes server to validate extractability_count > 0.
> If found 0, download would be reported as "not extractable".
> Most likely it's possible to use SftpClient::openRemoteFileChannel and work
> with the obtained FileChannel manually without any additional requests to
> stat remote file size.
> Though it would be a cumbersome approach, as reading remote file in chunks
> not knowing its size in this case will be far from optimal.
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