CA-406403: Do not return HTTP 500 when Accept header can't be parsed

[psafont]

/update_rrds returned a 500 HTTP code in some cases where the accept header was
invalid. Now these cases are treated in the same way as a lack of Accept
header.

[edwintorok]

I was checking whether an existing library could do this, all I could find was:
https://ocaml.org/p/httpaf_caged/latest/doc/Httpaf_caged/Accept/index.html
https://ocaml.org/p/dream-accept/latest

But they each depend on their own http libraries (httpaf and dream-message), and not the common http library.

[gangj]

I was checking whether an existing library could do this, all I could find was: https://ocaml.org/p/httpaf_caged/latest/doc/Httpaf_caged/Accept/index.html https://ocaml.org/p/dream-accept/latest

But they each depend on their own http libraries (httpaf and dream-message), and not the common http library.

Just a question, why didn't we use one of these http libraries, is it because there was no available library then? Thank you!

[psafont]

Just a question, why didn't we use one of these http libraries, is it because there was no available library then?

before 2012 OCaml didn't have a common repository of libraries (opam). So some may have existed, but the normal way of working was for everybody to build its own stack of libraries.

[lindig]

I this implementing the spec or deals with the cases we support? The spec has a lot of details that would require a parser.

[psafont]

The changes in the parser have brought a lot of uneeded attention, as the parsing wasn't being changed, only how the errors were transmitted. I've changed the PR to only document the existing parser and change how it's handled by the /update_rrds HTTP endpoint

[psafont]

Without the patch:

$ curl -k -sS -H "Accept: Garbage" -D - "https://xs-box/rrd_updates?session_id=OpaqueRef:634ef2ae-9599-f26d-1709-ef5ace1ce6fb&cf=AVERAGE&start=1738774514&host=true" -o /dev/null
HTTP/1.1 500 Internal Error
content-length: 277
content-type: text/html
connection: close
cache-control: no-cache, no-store

with the patch:

$ curl -k -sS -H "Accept: Garbage" -D - "https://xs-box/rrd_updates?session_id=OpaqueRef:067f4032-67a5-b6ec-ed73-450206054271&cf=AVERAGE&start=1738774514&host=true" -o /dev/null
HTTP/1.1 200 OK
Connection: keep-alive
Content-Length: 10816
Cache-Control: no-cache, no-store
content-type: text/xml
Access-Control-Allow-Origin: *
Access-Control-Allow-Headers: X-Requested-With