Go: x/net/webdav: fails on broken links

Created on 27 Jun 2016 · 3Comments · Source: golang/go

When trying to list a directory that contains a broken link I get a non informative error:

$ cadaver webdav://localhost:5555/api/v1/content                                                                                                                                         
dav:/api/v1/content/> ls etc
Listing collection `/api/v1/content/etc/': failed:
XML parse error at line 1: junk after document element

This is what I get from the webdav server:

2016/06/27 14:52:42 http: multiple response.WriteHeader calls

The error comes from file.go [1] where it calls stat on the broken link file but I think that maybe it should be handled in webdav.go walkFn [2].

I am not sure myself what should be printed / returned but I would expect to get the full directory listing (ie webdav shouldn't crush on this in my opinion) with this link marked a broken somehow .

[1] https://github.com/golang/net/blob/master/webdav/file.go#L779
[2] https://github.com/golang/net/blob/master/webdav/webdav.go#L527

/cc @simon3z

Source

enoodle

Most helpful comment

I just encounter this issue to. I fixed it locally by just returning nil when getting an error here https://github.com/golang/net/blob/master/webdav/webdav.go#L557.

I tested the same use case with Apache implementation and in the case of a broken symblink, it is silently discarded.

I don't know if it is a good enough solution but today's behavior is incorrect too.
Here is a wireshark trace of the faulty response

Host: 10.21.59.204
Depth: 1
Content-Type: application/xml
Apply-To-Redirect-Ref: T
Accept-Encoding: gzip, deflate
User-Agent: gvfs/1.28.2
Accept-Language: en-us, en;q=0.9
Connection: Keep-Alive
Content-Length: 235

<?xml version="1.0" encoding="utf-8" ?>
 <D:propfind xmlns:D="DAV:">
  <D:prop>
<D:creationdate/>
<D:displayname/>
<D:getcontentlength/>
<D:getcontenttype/>
<D:getetag/>
<D:getlastmodified/>
<D:resourcetype/>
  </D:prop>
 </D:propfind>HTTP/1.1 207 status code 207
Content-Type: text/xml; charset=utf-8
Date: Wed, 15 Mar 2017 09:00:40 GMT
Content-Length: 610

<?xml version="1.0" encoding="UTF-8"?><D:multistatus xmlns:D="DAV:"><D:response><D:href>/dav</D:href><D:propstat><D:prop><D:displayname></D:displayname><D:getlastmodified>Wed, 15 Mar 2017 08:59:55 GMT</D:getlastmodified><D:resourcetype><D:collection xmlns:D="DAV:"/></D:resourcetype></D:prop><D:status>HTTP/1.1 200 OK</D:status></D:propstat><D:propstat><D:prop><D:creationdate></D:creationdate><D:getcontentlength></D:getcontentlength><D:getcontenttype></D:getcontenttype><D:getetag></D:getetag></D:prop><D:status>HTTP/1.1 404 Not Found</D:status></D:propstat></D:response></D:multistatus>Internal Server Error

In the Webdav Spec it is said that

In the case of allprop and propname, if a principal does not have the
right to know whether a particular property exists then the property
should be silently excluded from the response.

I don't know if this apply in our use case

skritchz on 15 Mar 2017

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