[sane-devel] Canon I-Sensys MF4780w "push mode" scanning

[Alexander Lyashuk]

One more thing to add, maybe WSD will be an easier option.

It's possible to enable WSD support for this scanner.

In that case, I also can scan in "Remote scanner" mode through the
sane-airscan backend.
I can also start scanning to the windows machines from the scanner through
WSD (when I select "Scan" -> "Computer", all windows machines in my local
network appear, even ones without Canon drivers, unlike it was with
MFNP-only mode).

However, when I do `scanimage --device-name=airscan:w0:mf4780w -A`
similarly to what I attempted with MFNP mode, no new lines appear in the
list of destinations.
Also `scanimage -A` doesn't show the state of buttons in this case.


On Sun, Aug 15, 2021 at 11:43 AM Alexander Lyashuk <mooskagh at gmail.com>
wrote:

> Hi sane-devel,
>
> I have a Canon i-Sensys MF4780w network scanner/printer.
>
> It has two ways to start scanning:
> - "Remote scanner" / "pull mode", when you enable that mode on the device
> and then continue on the computer.
> - "Computer" / "push mode", where you select the destination and initiate
> scanning from the scanner itself.
>
> My scanner works well in "Remote scanner" mode (through the pixma backend,
> I've added "mfnp://10.162.0.7" to pixma.conf).
> I'd like to be able to initiate the scans from the scanner (in
> "Computer"/push mode) though, so that I can set up a headless server which
> will upload documents to Google Drive.
>
> So far I failed to set it up that way, and I wonder whether there is any
> hope.
>
> When I select "Scan" -> "Computer" on my scanner,
> - First I have to select the destination.
> - Then I select the mode (Color/BnW/Custom1/Custom2).
>
> I checked what Windows does to appear in the list of destinations, and it
> seems that it sends an MFNP message to the scanner every 5 seconds and so.
>
> I tried to do the same from Linux by calling `scanimage -A` in the loop.
> When I did that, a selectable extra empty line indeed appeared in the list
> of destinations on the scanner. I checked the messages from Windows and
> Linux in network sniffer and it appears that Windows sends the hostname in
> ASCII format, while on Linux it's UTF-16, that's the likely reason why the
> scanner cannot display the destination name properly.
> I wouldn't mind having an empty line as a hostname though as long as it
> would work.
>
> When I select "Scan" -> "Computer" -> "empty line" -> "Custom 1" (or
> BnW/Custom2/Color), both --button-1 and --button-2 still show value [0] in
> `scanimage -A`, so I cannot find any way to know I should start scanning.
>
> I also tried to use scanbd, but it appears not to be able to find the
> scanner at all:
>
> [root]# SANE_CONFIG_DIR=/usr/local/etc/scanbd/ ./scanbd -f -d7
> ./scanbd: reading config file /usr/local/etc/scanbd/scanbd.conf
> ./scanbd: debug on: level: 7
> ./scanbd: dropping privs to uid root
> ./scanbd: dropping privs to gid scanner
> ./scanbd: drop privileges to gid: 96
> ./scanbd: Running as effective gid 96
> ./scanbd: drop privileges to uid: 0
> ./scanbd: Running as effective uid 0
> ./scanbd: dbus_init
> ./scanbd: dbus match type='signal',interface='org.freedesktop.Hal.Manager'
> ./scanbd: SANE_CONFIG_DIR=/usr/local/etc/scanbd/
> ./scanbd: sane version 1.0
> ./scanbd: Scanning for local-only devices
> ./scanbd: start_sane_threads
> ./scanbd: no devices, not starting any polling thread
> ./scanbd: start dbus thread
> ./scanbd: Not Primary Owner (-1)
> ./scanbd: Name Error (Connection ":1.219" is not allowed to own the
> service "de.kmux.scanbd.server" due to security policies in the
> configuration file)
> ./scanbd: udev init
> ./scanbd: get udev monitor
> ./scanbd: udev fd is non-blocking, now setting to blocking mode
> ./scanbd: start udev thread
> ./scanbd: udev thread started
>
> Note the string "Scanning for local-only devices", does it mean it doesn't
> attempt to scan network devices?
>
> Any suggestions on what to try next would be very appreciated.
>
> Thanks!
>
>
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