fix(sirv): a request with range headers appends Content-Length, Conte…

[imtiazmangerah]

A request with Range headers present will result in the headers object being modified for all subsequent requests.

To reproduce:

curl -X GET  http://localhost:5000/pnggrad16rgb.png  -H 'Cache-Control: no-cache'

{
  'Content-Length': 3974,
  'Content-Type': 'image/png',
  'Last-Modified': 'Fri, 31 Jul 2020 04:30:09 GMT'
}

curl -X GET http://localhost:5000/pnggrad16rgb.png -H 'Cache-Control: no-cache' -H 'Range: bytes=0-499'

{
  'Content-Length': 500,
  'Content-Type': 'image/png',
  'Last-Modified': 'Fri, 31 Jul 2020 04:30:09 GMT',
  'Content-Range': 'bytes 0-499/3974',
  'Accept-Ranges': 'bytes'
}

curl -X GET  http://localhost:5000/pnggrad16rgb.png  -H 'Cache-Control: no-cache'

{
  'Content-Length': 500,
  'Content-Type': 'image/png',
  'Last-Modified': 'Fri, 31 Jul 2020 04:30:09 GMT',
  'Content-Range': 'bytes 0-499/3974',
  'Accept-Ranges': 'bytes'
}

Image used for above test:

[codecov-commenter]

Codecov Report

Merging #75 into master will not change coverage. The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #75   +/-   ##
=======================================
  Coverage   98.50%   98.50%           
=======================================
  Files           2        2           
  Lines          67       67           
=======================================
  Hits           66       66           
  Misses          1        1           

---

Continue to review full report at Codecov.

Legend - Click here to learn more Δ = absolute <relative> (impact), ø = not affected, ? = missing data Powered by Codecov. Last update f8ea6a8...f500c6c. Read the comment docs.

[lukeed]

Thanks! Do you think you could add test(s) for this? Could be able to do the same thing you've illustrated with curl but with any of the current assets/fixtures.

[imtiazmangerah]

@lukeed I think the test suite will have to include a few more cases which will fail even with the fix, example:

bytes=0-499, -500

[x,y] would be parsed incorrectly, yet that is a valid header for bytes.

Is it the intention of sirv to have full support for range requests?

[lukeed]

Let's worry about the other Range values separately. That's easy to address, but this PR should focus on the mutable headers reference you identified

[imtiazmangerah]

@lukeed gave the tests a go, first commit of tests passed, cleaned up the tests to avoid repetition and now checks failed. I cant spot what would cause that, any hints?