Crash on response 'Link" header parsing

[ivailop]

If a response 'Link' header not exactly formatted as:

Link: < uri-reference >; rel="value";

parsing it (as done at https://github.com/lostisland/sawyer/blob/master/lib/sawyer/response.rb#L52) results in a crash:

NoMethodError: undefined method `captures' for nil:NilClass
.../vendor/bundle/ruby/2.6.0/gems/sawyer-0.8.2/lib/sawyer/response.rb:52:in `block in process_rels'
.../vendor/bundle/ruby/2.6.0/gems/sawyer-0.8.2/lib/sawyer/response.rb:51:in `map'
.../vendor/bundle/ruby/2.6.0/gems/sawyer-0.8.2/lib/sawyer/response.rb:51:in `process_rels'
.../vendor/bundle/ruby/2.6.0/gems/sawyer-0.8.2/lib/sawyer/response.rb:20:in `initialize'
.../vendor/bundle/ruby/2.6.0/gems/sawyer-0.8.2/lib/sawyer/agent.rb:107:in `new'
.../vendor/bundle/ruby/2.6.0/gems/sawyer-0.8.2/lib/sawyer/agent.rb:107:in `call'
.../vendor/bundle/ruby/2.6.0/gems/octokit-4.19.0/lib/octokit/connection.rb:156:in `request'
.../vendor/bundle/ruby/2.6.0/gems/octokit-4.19.0/lib/octokit/connection.rb:28:in `post'
.../vendor/bundle/ruby/2.6.0/gems/octokit-4.19.0/lib/octokit/client/users.rb:57:in `exchange_code_for_token'

By specification (see https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Link) the generic format is:

Link: < uri-reference >; param1=value1; param2="value2"

where:

• the rel param is not required to be 1st
• the value is not required to be quoted

In fact recent change in GitHub's API the returned header is like:

link: "<https://github.githubassets.com/assets/chunk-frameworks-aaac5e7e.js>; integrity=sha512-qqxefjEZzhP8x0ed+F3sDEdSogyDs+0ThK6EYXtqye9PJ26t5C996Q9EuRBr+296TAbc1rimsOSeZjZXJac1cA==; rel=preload; crossorigin=anonymous; as=script,<https://github.githubassets.com/assets/chunk-vendor-6594a208.js>; integrity=sha512-ZZSiCHJ85gkTIyggKfuBXsl3a7e+GPhw6iUguJ6eki2dXkGnOFBpQlUUG+gcTSJzgE8ii1cYyM7aLYXZeSeDbA==; rel=preload; crossorigin=anonymous; as=script,<https://github.githubassets.com/assets/behaviors-bf28db4d.js>; integrity=sha512-vyjbTdEGTiemoiT41KyVSh3+NxJv285wa1qlccyGrTsQsAAvhBSUrT0t1LZbJVEfccSTx+zLAyTekiljOX2wKA==; rel=preload; crossorigin=anonymous; as=script,<https://github.githubassets.com/assets/environment-f0adafbf.js>; integrity=sha512-8K2vvwbW+6H27Nad5ydg8PA2/aMD/LKq+EiK9s0U0hhVZxCI2tWBsYk9beAtisRw2j+Or5k2/F+6dk02nmj/PA==; rel=preload; crossorigin=anonymous; as=script"

Notice:

• there is integrity before rel
• rel is not quoted
• there is no space after a , (comma)

[filipesperandio]

Had the same problem early this week with Sawyer within Octokit.