[mail.de] I/O error when acessing WebDAV file

[Tobl1248]

Problem scope

• I'm sure that this is a DAVx⁵ problem.

App version

• I'm using the latest available DAVx⁵ version.

Android version and device/firmware type

Android 14, Samsung SM-S918B/DS (Galaxy S23Ultra)

Steps to reproduce

1. Create WebDAV Access to mail.de -> okay
2. Navigate to a file -> okay
3. Share file (e.g. file manager -> error 'read failed', E-Mail -> expected content displayed with error symbol)

Actual result

Error message

Expected result

Share file without error.

Further info

• Same error comes when trying to access a file by using Keepass2Android or Material Files
• CalDAV is working fine

[rfc2822]

+1 Could reproduce it with our new mail.de test account (thanks @euuurgh).

Whenever DAVx5 requests a segment of a file, mail.de responds with 412:

--> GET https://speicher.mail.de/Online-Speicher/Dateieingang/kakaoparty.jpg h2
If-Match: "67f4ce74-66157"
Accept: image/jpeg, */*;q=0.8
Range: bytes=0-418134
User-Agent: DAVx5/4.4.8-ose (dav4jvm; okhttp/4.12.0) Android/15
Accept-Language: en-US, en;q=0.7, *;q=0.5
Accept-Encoding: br,gzip
Authorization: Basic xxx
Host: speicher.mail.de
Connection: Keep-Alive
--> END GET
<-- 412 https://speicher.mail.de/Online-Speicher/Dateieingang/kakaoparty.jpg (96ms)
server: nginx
date: Tue, 08 Apr 2025 07:23:25 GMT
content-type: application/xml; charset=utf-8
content-length: 312
etag: "cf91e545888fa08ae5cb94bfb1377412"
<-- END HTTP
Couldn't read from WebDAV resource
java.util.concurrent.ExecutionException: at.bitfire.dav4jvm.exception.PreconditionFailedException: HTTP 412 
	at com.google.common.util.concurrent.AbstractFuture.getDoneValue(AbstractFuture.java:292)
	at com.google.common.util.concurrent.AbstractFutureState.blockingGet(AbstractFutureState.java:231)
	at com.google.common.util.concurrent.Platform.get(Platform.java:54)
	at com.google.common.util.concurrent.AbstractFuture.get(AbstractFuture.java:253)
	at com.google.common.util.concurrent.AbstractFuture$TrustedFuture.get(AbstractFuture.java:96)
	at com.google.common.util.concurrent.Uninterruptibles.getUninterruptibly(Uninterruptibles.java:252)
	at com.google.common.cache.LocalCache$Segment.getAndRecordStats(LocalCache.java:2248)
…
Caused by: at.bitfire.dav4jvm.exception.PreconditionFailedException: HTTP 412 
	at at.bitfire.dav4jvm.DavResource.checkStatus(DavResource.kt:646)
	at at.bitfire.dav4jvm.DavResource.checkStatus(DavResource.kt:624)
	at at.bitfire.dav4jvm.DavResource.getRange(DavResource.kt:404)
	at at.bitfire.davdroid.webdav.RandomAccessCallback$PageLoader$load$job$1.invokeSuspend$lambda$1(RandomAccessCallback.kt:203)
	at at.bitfire.davdroid.webdav.RandomAccessCallback$PageLoader$load$job$1.$r8$lambda$dnHSGQG-OAPkzEM2ChSXsplrZok(Unknown Source:0)
	at at.bitfire.davdroid.webdav.RandomAccessCallback$PageLoader$load$job$1$$ExternalSyntheticLambda1.invoke(D8$$SyntheticClass:0)
	at kotlinx.coroutines.InterruptibleKt.runInterruptibleInExpectedContext(Interruptible.kt:48)
…
NowIdle triggers DefaultTransition from DefaultState(transferring) to [DefaultState(idle)]
Exiting DefaultState(transferring)
Parent DefaultState(active) entering child DefaultState(idle)
android.system.ErrnoException: onRead failed: EIO (I/O error)
	at at.bitfire.davdroid.webdav.RandomAccessCallback.toErrNoException(RandomAccessCallback.kt:147)
	at at.bitfire.davdroid.webdav.RandomAccessCallback.onRead(RandomAccessCallback.kt:124)
	at at.bitfire.davdroid.webdav.RandomAccessCallbackWrapper.onRead$lambda$2(RandomAccessCallbackWrapper.kt:177)
…
Caused by: java.util.concurrent.ExecutionException: at.bitfire.dav4jvm.exception.PreconditionFailedException: HTTP 412 
	at com.google.common.util.concurrent.AbstractFuture.getDoneValue(AbstractFuture.java:292)
	at com.google.common.util.concurrent.AbstractFutureState.blockingGet(AbstractFutureState.java:231)
	at com.google.common.util.concurrent.Platform.get(Platform.java:54)
	at com.google.common.util.concurrent.AbstractFuture.get(AbstractFuture.java:253)
	at com.google.common.util.concurrent.AbstractFuture$TrustedFuture.get(AbstractFuture.java:96)
	at com.google.common.util.concurrent.Uninterruptibles.getUninterruptibly(Uninterruptibles.java:252)
	at com.google.common.cache.LocalCache$Segment.getAndRecordStats(LocalCache.java:2248)
	at com.google.common.cache.LocalCache$Segment.loadSync(LocalCache.java:2216)
…

[rfc2822]

mail.de responds with 412 when sending If-Match: <etag of the file>:

$ curl -Ivu xxx:xxx https://speicher.mail.de/Online-Speicher/Dateieingang/kakaoparty.jpg
…
< etag: "67f4ce74-66157"
etag: "67f4ce74-66157"
< accept-ranges: bytes
accept-ranges: bytes

So the server supports range requests and the file has an ETag of 67f4ce74-66157.

When requesting the file with If-Match:

$ curl -vH 'If-Match: "67f4ce74-66157"' -u xxx:xxx https://speicher.mail.de/Online-Speicher/Dateieingang/kakaoparty.jpg
…
> GET /Online-Speicher/Dateieingang/kakaoparty.jpg HTTP/2
> Host: speicher.mail.de
> Authorization: Basic XXX
> User-Agent: curl/8.9.1
> Accept: */*
> If-Match: "67f4ce74-66157"
…
< HTTP/2 412
< server: nginx
< date: Tue, 08 Apr 2025 08:08:12 GMT
< content-type: application/xml; charset=utf-8
< content-length: 312
< etag: "cf91e545888fa08ae5cb94bfb1377412"
<
<?xml version="1.0" encoding="utf-8"?>
<d:error xmlns:d="DAV:" xmlns:s="http://sabredav.org/ns">
  <s:exception>Sabre\DAV\Exception\PreconditionFailed</s:exception>
  <s:message>An If-Match header was specified, but none of the specified the ETags matched.</s:message>
  <s:header>If-Match</s:header>
</d:error>

As I understand it, this is wrong. Instead, the file should just be returned.

Same for a ranged request:

$ curl -vr 0-500 -H 'If-Match: "67f4ce74-66157"' -u 'xxx:xxx' https://speicher.mail.de/Online-Speicher/Dateieingang/kakaoparty.jpg
…
> GET /Online-Speicher/Dateieingang/kakaoparty.jpg HTTP/2
> Host: speicher.mail.de
> Authorization: Basic XXX
> Range: bytes=0-500
> User-Agent: curl/8.9.1
> Accept: */*
> If-Match: "67f4ce74-66157"
…
< HTTP/2 412
< server: nginx
< date: Tue, 08 Apr 2025 08:09:01 GMT
< content-type: application/xml; charset=utf-8
< content-length: 312
< etag: "cf91e545888fa08ae5cb94bfb1377412"
<
<?xml version="1.0" encoding="utf-8"?>
<d:error xmlns:d="DAV:" xmlns:s="http://sabredav.org/ns">
  <s:exception>Sabre\DAV\Exception\PreconditionFailed</s:exception>
  <s:message>An If-Match header was specified, but none of the specified the ETags matched.</s:message>
  <s:header>If-Match</s:header>
</d:error>

Only when a range request with If-Range instead of If-Match is used, the request is fulfilled:

$ curl -vr 0-500 -H 'If-Range: "x67f4ce74-66157"' -u 'xxx:xxx' https://speicher.mail.de/Online-Speicher/Dateieingang/kakaoparty.jpg --output response-body.bin
…
> GET /Online-Speicher/Dateieingang/kakaoparty.jpg HTTP/2
> Host: speicher.mail.de
> Authorization: Basic xxx
> Range: bytes=0-500
> User-Agent: curl/8.9.1
> Accept: */*
> If-Range: "x67f4ce74-66157"
…
< HTTP/2 200
< server: nginx
< date: Tue, 08 Apr 2025 08:11:41 GMT
< content-type: image/jpeg
< content-length: 418135
< last-modified: Tue, 08 Apr 2025 07:21:24 GMT
< etag: "67f4ce74-66157"
< accept-ranges: bytes
…
$ du --bytes response-body.bin
501

From my understanding, this is not expected behavior. If-Range adds a second check and fallback to If-Match, which is not desired in our case. If-Match however MUST work, and in my test it didn't even work with a normal non-ranged request.

Can you please verify that and/or report it to mail.de with link to this discussion?

Will re-open if there's an indication that this is a DAVx5 problem.

[PHPGangsta]

Hello,

I'm working for mail.de.

We can confirm this is not a bug in DAVx5, it's an issue on our side. We are using a reverse-proxy, and this reverse-proxy has a different ETag calculation algorithm than the WebDAV application, which leads to the problem you see. We quickly tried a hotfix in a test environment and it works, but it does not scale in the live environment. We will work on this issue to solve it.

[rfc2822]

Thanks for the quick follow-up and information!

[Tobl1248]

Hello all,thank you very much for your support!BRThomas  -------- Ursprüngliche Nachricht --------Von: Michael Kliewe ***@***.***> Datum: 10.04.25 18:08 (GMT+01:00) An: bitfireAT/davx5-ose ***@***.***> Cc: Tobl1248 ***@***.***>, Author ***@***.***> Betreff: Re: [bitfireAT/davx5-ose] [mail.de] I/O error when acessing WebDAV file (Issue #1365) Hello, I'm working for mail.de. We can confirm this is not a bug in DAVx5, it's an issue on our side. We are using a reverse-proxy, and this reverse-proxy has a different ETag calculation algorithm than the WebDAV application, which leads to the problem you see. We quickly tried a hotfix in a test environment and it works, but it does not scale in the live environment. We will work on this issue to solve it.—Reply to this email directly, view it on GitHub, or unsubscribe.You are receiving this because you authored the thread.Message ID: ***@***.***> PHPGangsta left a comment (bitfireAT/davx5-ose#1365) Hello, I'm working for mail.de. We can confirm this is not a bug in DAVx5, it's an issue on our side. We are using a reverse-proxy, and this reverse-proxy has a different ETag calculation algorithm than the WebDAV application, which leads to the problem you see. We quickly tried a hotfix in a test environment and it works, but it does not scale in the live environment. We will work on this issue to solve it. —Reply to this email directly, view it on GitHub, or unsubscribe.You are receiving this because you authored the thread.Message ID: ***@***.***>