[bug] Host matching not work without scheme?

[pierreneter]

Describe the bug

About: Matching Routes - Host

https://github.com/gorilla/mux#matching-routes

The docs:

r := mux.NewRouter()
// Only matches if domain is "www.example.com".
r.Host("www.example.com") // this
// Matches a dynamic subdomain.
r.Host("{subdomain:[a-z]+}.example.com")

It will not work if the host is passed in without a scheme.

Versions

Go version: go version go1.13.4 darwin/amd64
package version: github.com/gorilla/mux v1.7.3

Steps to Reproduce / Code Snippets

This not work:

func main() {
	r := mux.NewRouter()
	r.Host("localhost:8080")
	r.Handle("/", http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Write([]byte("ok"))
	}))
	http.ListenAndServe(":8080", r)
}

This work:

func main() {
	r := mux.NewRouter()
	r.Host("http://localhost:8080")
	r.Handle("/", http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Write([]byte("ok"))
	}))
	http.ListenAndServe(":8080", r)
}

Expected behavior

Work without scheme

[76creates]

also to add:
when you match host like r.Host("localhost:8080") it acts as a inverse, allowing all but that host
when you match like r.Host("http://localhost:8080") it allows all hosts regardless

I found it only working as expected when you chain .Host(...) to the r.Handle(...)

[elithrar]

The examples in the docs may be a little confusing.

If you say r.Host without attaching a Route, you've created a matcher without a subsequent handler to call - which is why you see it "not allowing" that host.

You should either:

s := r.Host("sub.example.com").Subrouter()
s.HandleFunc("/", yourHandler)

... or use .PathPrefix to match all requests to that host. Calling r.Host on its own will effectively blackhole the matches.

[fharding1]

I've seen a few issues from people confused by this behavior, and I think it's just the nature of the builder pattern mux uses. It makes sense, it's just not very intuitive to people new to mux. It could help to add a sentence to the Matching Routes section of the README that says something along the lines of: "Matchers without attached handlers will still match routes, however they will 404, even taking priority over routes with handlers (if added first)." with maybe an example similar to @pierreneter 's.

[elithrar]

Agree. I think a new “How does mux Match Routes?” section in the README / doc.go is warranted.

…

On Fri, Nov 29, 2019 at 7:45 PM Franklin Harding ***@***.***> wrote: I've seen a few issues from people confused by this behavior, and I think it's just the nature of the builder pattern mux uses. It makes sense, it's just not very intuitive to people new to mux. It could help to add a sentence to the Matching Routes section of the README that says something along the lines of: "Matchers without attached handlers will still match routes, however they will 404, even taking priority over routes with handlers (if added first)." with maybe an example similar to @pierreneter <https://github.com/pierreneter> 's. — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#530?email_source=notifications&email_token=AAAEQ4BW2FW6WW2DJW7JBYLQWHOTZA5CNFSM4JIR5PPKYY3PNVWWK3TUL52HS4DFVREXG43VMVBW63LNMVXHJKTDN5WW2ZLOORPWSZGOEFPYVIA#issuecomment-559909536>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAAEQ4DXJUNWZWCP5QMH4R3QWHOTZANCNFSM4JIR5PPA> .

[teraflik]

I think #474 should resolve this.

[stale]

This issue has been automatically marked as stale because it hasn't seen a recent update. It'll be automatically closed in a few days.