About authentication

[jurivrljicak]

Hello,

I don't understand why sometimes I am asked to authenticate and sometimes I am not.
Can I disable this functionality?

If I choose to enable it, I am not very clear how to use it either.

I put this file in place.

~/.sane/pass
This file contains lines of the form
user:password:resource

...where the password is the default pass for a particular device? (I can't find that on the manual)

thanks a lot

java.io.IOException: Authorization failed - the password provider is unable to provide a password for the resource [
     at au.com.southsky.jfreesane.SaneSession.authorize(SaneSession.java:351)
     at au.com.southsky.jfreesane.SaneSession.openDevice(SaneSession.java:195)
     at au.com.southsky.jfreesane.SaneDevice.open(SaneDevice.java:77)
     at com.xxx.service.image.manager.sane.jsane.JSaneDeviceImpl$2.doWithRetry(JSaneDeviceImpl.java:248)
     at com.xxx.service.image.manager.sane.jsane.JSaneDeviceImpl$2.doWithRetry(JSaneDeviceImpl.java:1)
     at org.springframework.retry.support.RetryTemplate.doExecute(RetryTemplate.java:329)
     at org.springframework.retry.support.RetryTemplate.execute(RetryTemplate.java:209)
     at com.xxx.service.image.manager.sane.jsane.JSaneDeviceImpl.openDevice(JSaneDeviceImpl.java:243)

[sjamesr]

Are any of your resources password-protected? What does /etc/sane.d/saned.users contain?

The format of the password file is <user>:<password>:<resource>, see man saned(2):

       /etc/sane.d/saned.users
              If this file contains lines of the form

              user:password:backend

              access to the listed backends is restricted. A backend may be listed multiple times for different user/password combinations. The server uses MD5 hashing if supported by the
              client.

[jurivrljicak]

I am sorry I don't follow from before. How do I set up a password?
thanks

[sjamesr]

You have to look at the SANE server configuration to see if any of the resources (i.e. scanners) are password protected. Does your server have a /etc/sane.d/saned.users file?

[jurivrljicak]

no it does'nt.

But why don't I get a consistent behavior in here?

SaneDeviceHandle openDevice(SaneDevice device) throws IOException, SaneException {

    [...code..]

    SaneWord handle = inputStream.readWord();
    String resource = inputStream.readString();

    if (!resource.isEmpty()) {
      authorize(resource);
      status = inputStream.readWord();
      handle = inputStream.readWord();
      resource = inputStream.readString();
      if (status.integerValue() != 0) {
        throw new SaneException(SaneStatus.fromWireValue(status.integerValue()));
      }
    }

    return new SaneDeviceHandle(status, handle, resource);
  }

[sjamesr]

Can you send me the code that you're using to call into JFreeSane? Are you saying you have no passwords configured on any of your scanners, yet JFreeSane is still trying to authenticate? If so, perhaps you could capture a packet dump of an interaction between JFreeSane and SANE, e.g.

tcpdump port 6566 -w /tmp/out.pcap
<run jfreesane>

and send me the resulting out.pcap.

[jurivrljicak]

Ok I'll try that and I'll be back, thank you.

Are you saying you have no passwords configured on any of your scanners, yet JFreeSane is still trying to authenticate?

Yes.

In the meantime this is what I have:

INFO: KODAK/i900/sheetfed scanner
Jan 30, 2021 9:40:57 AM com.xxx.service.image.manager.sane.jsane.JSaneDeviceImpl$3 onError
SEVERE: Error trying operation: Connect to Jsane device, occ=1, excep= au.com.southsky.jfreesane.SaneException:STATUS_INVAL
Jan 30, 2021 9:41:12 AM com.xxx.service.image.manager.sane.jsane.JSaneDeviceImpl$3 onError
SEVERE: Error trying operation: Connect to Jsane device, occ=2, excep= java.io.IOException:Authorization failed - the password provider is unable to provide a password for the resource [

The resource is '[' and I don't know what that means. In the case where it works the resource is '' (empty). I guess that is what I want.

[sjamesr]

Yeah it definitely looks like something is going wrong in the stream, most likely a bug in jfreesane somewhere. Hopefully I'll be able to track it down with a pcap dump. Thanks for reporting it.

…

On Sun, Feb 7, 2021 at 7:23 AM jurivrljicak ***@***.***> wrote: Ok I'll try that and I'll be back, thank you. In the meantime this is what I have: INFO: KODAK/i900/sheetfed scanner Jan 30, 2021 9:40:57 AM com.xxx.service.image.manager.sane.jsane.JSaneDeviceImpl$3 onError SEVERE: Error trying operation: Connect to Jsane device, occ=1, excep= au.com.southsky.jfreesane.SaneException:STATUS_INVAL Jan 30, 2021 9:41:12 AM com.aws.service.image.manager.sane.jsane.JSaneDeviceImpl$3 onError SEVERE: Error trying operation: Connect to Jsane device, occ=2, excep= java.io.IOException:Authorization failed - the password provider is unable to provide a password for the resource [ The resource is '[' and I don't know what that means. In the case where it works the resource is '' (empty). I guess that is what I want. — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#104 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ABDNGAZKIMZPHGI462R34B3S52V6DANCNFSM4WXQ6QCA> .

[jurivrljicak]

Ok great I'll try to get to into that condition. It's kind of random or somehow related to when things get idle for some time.
Thanks!

[jurivrljicak]

I made a capture with Wireshark for my virtual machine interface to capture something. With the command you mentioned I got nothing for that port (I am using that default port).

Got the error and reran the code

Here it is what I got , let me know if its of any use.

authenticationJfreeSane.pcapng.zip

[jurivrljicak]

Here is another, thanks

out.pcap.zip

[jurivrljicak]

I haven't found a solution yet but I have a hint.

Before the authentication error I get a INVAL status. Looks like the connection gets into that state for some reason (not sure what reason). If I close and open the cover of my kodak things go back to normal. I have to emulate that manual procedure in the code as a workaround....I guess.

[sjamesr]

I didn't find any SANE traffic in either of the packet dumps you sent me. Can you share the code that uses jfreesane?

Do you call listDevices() and get back an empty list at any point? If so, that was fixed by #101 and you might want to try jfreesane built from HEAD.

[jurivrljicak]

Well, that fix made no difference.

My workaround when I get into that state (INVAL) is to restart the saned deamon from the app and things get back to work.

Ok, thx for your time.
Cheers