Angular 13 sending application/octet-stream MIME type for unknown files

[acalvo]

🐞 Bug report

Command (mark with an x)

• new
• build
• serve
• test
• e2e
• generate
• add
• update
• lint
• extract-i18n
• run
• config
• help
• version
• doc

Is this a regression?

Yes, the previous version in which this bug was not present was: 12.x

Description

Until now, a file without extension was served by Angular in dev mode (ng serve) with the ; charset=UTF8 Content-Type header, which enabled the MIME type sniffing making the browser treat it correctly. With Angular 13 the header changed to application/octet-stream which made the browser try to download it.

We set the appropriate headers to file in production, but this can't be done in the dev server as long as I know, so we relied in MIME type sniffing for dev mode until now.

🔬 Minimal Reproduction

Create any asset without extension (for example a simple html file without extension), run ng serve and navigate to that URL. In Angular12 it'll be displayed, in Angular13 the browser will ask to download it.

🔥 Exception or Error

🌍 Your Environment

Angular CLI: 13.0.1
Node: 14.17.1
Package Manager: npm 7.24.1
OS: darwin x64

Angular: 13.0.0
... animations, cdk, common, compiler, compiler-cli, core, forms
... language-service, localize, material, platform-browser
... platform-browser-dynamic, router, service-worker

Package                         Version
---------------------------------------------------------
@angular-devkit/architect       0.1202.7
@angular-devkit/build-angular   13.0.1
@angular-devkit/core            12.2.7
@angular-devkit/schematics      13.0.1
@angular/cli                    13.0.1
@schematics/angular             13.0.1
rxjs                            6.6.7
typescript                      4.4.4

Anything else relevant?

[alan-agius4]

Hi @acalvo,

Using application/octet-stream in this case seems to be the correct behaviour for files without extensions, especially considering the webpack-dev-server uses Express engine under the hood. Related test in webpack-dev-middleware.

This also aligns with the spec found in https://tools.ietf.org/html/rfc2045

Any entity with an unrecognized Content-Transfer-Encoding must be treated as if it has a Content-Type of "application/octet-stream", regardless of what the Content-Type header field actually says.

Files without extensions are also handled different from one server engine to another, there is a good comparison here. I therefore don't recommand using a file without extension.

[alan-agius4]

Closing as this seems to be working as design by Express engine.

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