Requesting binaries with invalid Accept headers should 406, not 500

[dmitrizagidulin]

Reported by @timbl:

If you request a non-rdf resource (say a PDF file) with an accept header like Accept:image/*;q=0.9, application/rdf+xml, application/xhtml+xml, text/xml;q=0.2, application/xml;q=0.2, text/html;q=0.3, text/plain;q=0.1, text/n3;q=1.0, application/x-turtle;q=1, text/turtle;q=1, the server will try to convert it from PDF to RDF, and fail with a 500 error.
Should instead return a 406 Unacceptable.

• something like application/ld+json,application/json,/;q=0.1 ??

On Fri., 9 Sep. 2016, 12:03 am Dmitri Zagidulin, notifications@github.com
wrote:

Reported by @timbl https://github.com/timbl:

If you request a non-rdf resource (say a PDF file) with an accept header
like Accept:image/*;q=0.9, application/rdf+xml, application/xhtml+xml,
text/xml;q=0.2, application/xml;q=0.2, text/html;q=0.3, text/plain;q=0.1,
text/n3;q=1.0, application/x-turtle;q=1, text/turtle;q=1, the server will
try to convert it from PDF to RDF, and fail with a 500 error.
Should instead return a 406 Unacceptable.

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[dmitrizagidulin]

@mediaprophet not sure I understand - explain more?

The original note didn't include json-ld.

On Fri., 9 Sep. 2016, 12:12 am Dmitri Zagidulin, notifications@github.com
wrote:

@mediaprophet https://github.com/mediaprophet not sure I understand -
explain more?

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[dmitrizagidulin]

@mediaprophet thanks!

[timbl]

A way to fix the original request was with with say /; q=1 in other words "if all else fails give me what you got " ... Then you will never get 406 error -- but you might get a massive file you can't do anything with. But that's not the point of this bug

[gklyne]

I'm getting this problem with a newly installed solid server attempting to access root path:

$ curl -v -H "accept: text/turtle" https://localhost:8443/
*   Trying ::1...
* Connected to localhost (::1) port 8443 (#0)
* TLS 1.2 connection using TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256
* Server certificate: localhost
> GET / HTTP/1.1
> Host: localhost:8443
> User-Agent: curl/7.43.0
> accept: text/turtle
>
< HTTP/1.1 500 Internal Server Error
< X-Powered-By: solid-server
< Vary: Accept, Authorization, Origin
< Access-Control-Allow-Credentials: true
< Access-Control-Expose-Headers: Authorization, User, Location, Link, Vary, Last-Modified, ETag, Accept-Patch, Accept-Post, Updates-Via, Allow, WAC-Allow, Content-Length, WWW-Authenticate
< Allow: OPTIONS, HEAD, GET, PATCH, POST, PUT, DELETE
< Link: <.acl>; rel="acl", <.meta>; rel="describedBy", <http://www.w3.org/ns/ldp#Resource>; rel="type"
< WAC-Allow: user="read",public="read"
< MS-Author-Via: SPARQL
< Updates-Via: wss://localhost:8443
< Content-Type: text/plain; charset=utf-8
< Content-Length: 38
< ETag: W/"26-QBI7EYtDt6zJzGYxyvtGCQrnW5Q"
< Date: Wed, 20 Feb 2019 10:48:49 GMT
< Connection: keep-alive
<
Error translating between RDF formats
* Connection #0 to host localhost left intact

(I would argue that any 500 response is a bug. In this case, it's a bit hostile for developers who are new to working with solid-server - not so good DX?)

I can't see a Github option to reopen this

In case it helps, here's the server log:

  solid:get / on localhost +0ms
  solid:handlers GET -- Reading /Users/graham/solid/data/index.html +1ms
[xmldom error]	entity not found:–
@#[line:8,col:3]
[xmldom error]	entity not found:–
@#[line:17,col:27]
  solid:get error translating: / text/html -> text/turtle -- 500 RDFaProcessor.trim is not a function +2ms
  solid:server Error page because of: { [HTTPError: Error translating between RDF formats]
  name: 'HTTPError',
  message: 'Error translating between RDF formats',
  status: 500 } +0ms

[gklyne]

I'm encountering a similar problem for which I have isolated a test case.

Test code is at https://github.com/oerc-music/meld-cli-tools/blob/master/spike/solid-create-read-text-resource.js

Overall:

1. create text/plain resource using POST
2. retrieve resource using GET with Accept: text/turtle

I would expect 406 response.

Server responds with 500

  response:
   { status: 500,
     statusText: 'Internal Server Error',
  : 

Server log shows:

  solid:get /public/9264b7b0-test.txt on localhost +0ms
  solid:handlers GET -- Reading /Users/graham/solid/data/public/9264b7b0-test.txt +0ms
  solid:get error translating: /public/9264b7b0-test.txt text/plain -> text/turtle -- 500 Don't know how to parse text/plain yet +1ms
  solid:server Error page because of: { [HTTPError: Error translating between RDF formats]
  name: 'HTTPError',
  message: 'Error translating between RDF formats',
  status: 500 } +0ms

Server version is:

Solid server (5.0.0-beta.7) running on https://localhost:8443/

[kjetilk]

OK, interesting! We have a bug open for the translation problem in #1120 , but this seems to be deeper too.

[gklyne]

yeah, #1120 looks similar to me. Not sure about the "deeper" bit. Hopefully the stand-alone test code can help (it depends on having axios installed, and needs to be edited with a valid bearer token).