dav: Fix handling of chunked WebDAV upload

[jplitza]

When $data is null (which can happen when $request->getBodyAsStream() returns null), the Exceptions says "copied bytes: 0, expected filesize: 0", which sounds more like success... So treat it as such!

This regression (it worked in Nextcloud 14) was probably introduced by commit 93de637

The setup resulting in this situation was a Canon iR-ADV C5030 uploading its scans via WebDAV to an SFTP external storage. Here is the error that resulted in an HTTP Error 500 being returned:

Nextcloud log (data/nextcloud.log)

Nextcloud log

{
"reqId": "AQ84OEsk9APcLfSPb4tu",
"level": 4,
"time": "2019-01-28T12:36:20+00:00",
"remoteAddr": "<redacted>",
"user": "<redacted>",
"app": "webdav",
"method": "PUT",
"url": "/remote.php/webdav/<redacted>",
"message": {
"Exception": "Sabre\\DAV\\Exception",
"Message": "Error while copying file to target location (copied bytes: 0, expected filesize: 0 )",
"Code": 0,
"Trace": [
{
"file": "/var/www/vhosts/<redacted>/httpdocs/apps/dav/lib/Connector/Sabre/Directory.php",
"line": 156,
"function": "put",
"class": "OCA\\DAV\\Connector\\Sabre\\File",
"type": "->",
"args": [
null
]
},
{
"file": "/var/www/vhosts/<redacted>/httpdocs/3rdparty/sabre/dav/lib/DAV/Server.php",
"line": 1096,
"function": "createFile",
"class": "OCA\\DAV\\Connector\\Sabre\\Directory",
"type": "->",
"args": [
"20190128125733.pdf",
null
]
},
{
"file": "/var/www/vhosts/<redacted>/httpdocs/3rdparty/sabre/dav/lib/DAV/CorePlugin.php",
"line": 525,
"function": "createFile",
"class": "Sabre\\DAV\\Server",
"type": "->",
"args": [
"NAS/20190128125733.pdf",
null,
null
]
},
{
"function": "httpPut",
"class": "Sabre\\DAV\\CorePlugin",
"type": "->",
"args": [
{
"absoluteUrl": "https://<redacted>:443/remote.php/webdav/<redacted>",
"__class__": "Sabre\\HTTP\\Request"
},
{
"__class__": "Sabre\\HTTP\\Response"
}
]
},
{
"file": "/var/www/vhosts/<redacted>/httpdocs/3rdparty/sabre/event/lib/EventEmitterTrait.php",
"line": 105,
"function": "call_user_func_array",
"args": [
[
{
"__class__": "Sabre\\DAV\\CorePlugin"
},
"httpPut"
],
[
{
"absoluteUrl": "https://<redacted>:443/remote.php/webdav/<redacted>",
"__class__": "Sabre\\HTTP\\Request"
},
{
"__class__": "Sabre\\HTTP\\Response"
}
]
]
},
{
"file": "/var/www/vhosts/<redacted>/httpdocs/3rdparty/sabre/dav/lib/DAV/Server.php",
"line": 479,
"function": "emit",
"class": "Sabre\\Event\\EventEmitter",
"type": "->",
"args": [
"method:PUT",
[
{
"absoluteUrl": "https://<redacted>:443/remote.php/webdav/<redacted>",
"__class__": "Sabre\\HTTP\\Request"
},
{
"__class__": "Sabre\\HTTP\\Response"
}
]
]
},
{
"file": "/var/www/vhosts/<redacted>/httpdocs/3rdparty/sabre/dav/lib/DAV/Server.php",
"line": 254,
"function": "invokeMethod",
"class": "Sabre\\DAV\\Server",
"type": "->",
"args": [
{
"absoluteUrl": "https://<redacted>:443/remote.php/webdav/<redacted>",
"__class__": "Sabre\\HTTP\\Request"
},
{
"__class__": "Sabre\\HTTP\\Response"
}
]
},
{
"file": "/var/www/vhosts/<redacted>/httpdocs/apps/dav/appinfo/v1/webdav.php",
"line": 80,
"function": "exec",
"class": "Sabre\\DAV\\Server",
"type": "->",
"args": []
},
{
"file": "/var/www/vhosts/<redacted>/httpdocs/remote.php",
"line": 163,
"args": [
"/var/www/vhosts/<redacted>/httpdocs/apps/dav/appinfo/v1/webdav.php"
],
"function": "require_once"
}
],
"File": "/var/www/vhosts/<redacted>/httpdocs/apps/dav/lib/Connector/Sabre/File.php",
"Line": 191,
"CustomMessage": "--"
},
"userAgent": "UniversalSend_WebDAV/1.0",
"version": "15.0.2.0"
}

[MorrisJobke]

When $data is null (which can happen when $request->getBodyAsStream() returns null), the Exceptions says "copied bytes: 0, expected filesize: 0", which sounds more like success... So treat it as such!

Just to summarize:

this can be triggered by uploading an empty file?

[jplitza]

@MorrisJobke No. The PDF uploaded by the scanner definitely isn't empty, and on the other hand uploading an empty TXT via gvfs didn't trigger the bug. I guess the scanner just starts with an empty body in the first request of a chunked transfer.

[ariselseng]

This fixes it for me. I triggered the bug by running touch to create an empty file and make the nextcloud desktop client sync it. I get http 500 without this fix.

[ariselseng]

this can be triggered by uploading an empty file?

@MorrisJobke You are right. I triggered this bug by syncing an empty file with the desktop client.

[MorrisJobke]

Code makes sense 👍

[MorrisJobke]

Status of 15220: failure

• TESTS=acceptance, TESTS-ACCEPTANCE=app-comments
  • cancelled
• TESTS=acceptance, TESTS-ACCEPTANCE=app-files-tags
  • tests/acceptance/features/app-files-tags.feature:70

Show full log

 Scenario: remove tags using the dropdown in the details view # /drone/src/github.com/nextcloud/server/tests/acceptance/features/app-files-tags.feature:70
Given I am logged in as the admin # LoginPageContext::iAmLoggedInAsTheAdmin()
And I visit the settings page # SettingsMenuContext::iVisitTheSettingsPage()
And I open the "Workflow" section # AppNavigationContext::iOpenTheSection()
And I see that the button to select tags is shown # SettingsContext::iSeeThatTheButtonToSelectTagsIsShown()
And I create the tag "tag1" in the settings # SettingsContext::iCreateTheTagInTheSettings()
And I create the tag "tag2" in the settings # SettingsContext::iCreateTheTagInTheSettings()
And I create the tag "tag3" in the settings # SettingsContext::iCreateTheTagInTheSettings()
And I create the tag "tag4" in the settings # SettingsContext::iCreateTheTagInTheSettings()
And I see that the dropdown for tags in the settings eventually contains the tag "tag1" # SettingsContext::iSeeThatTheDropdownForTagsInTheSettingsEventuallyContainsTheTag()
And I see that the dropdown for tags in the settings eventually contains the tag "tag2" # SettingsContext::iSeeThatTheDropdownForTagsInTheSettingsEventuallyContainsTheTag()
And I see that the dropdown for tags in the settings eventually contains the tag "tag3" # SettingsContext::iSeeThatTheDropdownForTagsInTheSettingsEventuallyContainsTheTag()
And I see that the dropdown for tags in the settings eventually contains the tag "tag4" # SettingsContext::iSeeThatTheDropdownForTagsInTheSettingsEventuallyContainsTheTag()
And I log out # SettingsMenuContext::iLogOut()
And I am logged in # LoginPageContext::iAmLoggedIn()
And I open the details view for "welcome.txt" # FileListContext::iOpenTheDetailsViewFor()
And I open the input field for tags in the details view # FilesAppContext::iOpenTheInputFieldForTagsInTheDetailsView()
And I check the tag "tag2" in the dropdown for tags in the details view # FilesAppContext::iCheckTheTagInTheDropdownForTagsInTheDetailsView()
And I check the tag "tag4" in the dropdown for tags in the details view # FilesAppContext::iCheckTheTagInTheDropdownForTagsInTheDetailsView()
And I check the tag "tag3" in the dropdown for tags in the details view # FilesAppContext::iCheckTheTagInTheDropdownForTagsInTheDetailsView()
When I uncheck the tag "tag2" in the dropdown for tags in the details view # FilesAppContext::iUncheckTheTagInTheDropdownForTagsInTheDetailsView()
And I uncheck the tag "tag4" in the dropdown for tags in the details view # FilesAppContext::iUncheckTheTagInTheDropdownForTagsInTheDetailsView()
Then I see that the tag "tag2" in the dropdown for tags in the details view is not checked # FilesAppContext::iSeeThatTheTagInTheDropdownForTagsInTheDetailsViewIsNotChecked()
And I see that the tag "tag4" in the dropdown for tags in the details view is not checked # FilesAppContext::iSeeThatTheTagInTheDropdownForTagsInTheDetailsViewIsNotChecked()
And I see that the tag "tag3" in the dropdown for tags in the details view is checked # FilesAppContext::iSeeThatTheTagInTheDropdownForTagsInTheDetailsViewIsChecked()
And I see that the input field for tags in the details view does not contain the tag "tag2" # FilesAppContext::iSeeThatTheInputFieldForTagsInTheDetailsViewDoesNotContainTheTag()
Failed asserting that false is true.
And I see that the input field for tags in the details view does not contain the tag "tag4" # FilesAppContext::iSeeThatTheInputFieldForTagsInTheDetailsViewDoesNotContainTheTag()
And I see that the input field for tags in the details view contains the tag "tag3" # FilesAppContext::iSeeThatTheInputFieldForTagsInTheDetailsViewContainsTheTag()

[MorrisJobke]

Failure is unrelated.

[MorrisJobke]

/backport to stable15

[backportbot-nextcloud]

backport to stable15 in #14517