podman
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1package handlers2
3import (4"net/http"5"net/url"6"strings"7)
8
9type canonical struct {10h http.Handler11domain string12code int13}
14
15// CanonicalHost is HTTP middleware that re-directs requests to the canonical
16// domain. It accepts a domain and a status code (e.g. 301 or 302) and
17// re-directs clients to this domain. The existing request path is maintained.
18//
19// Note: If the provided domain is considered invalid by url.Parse or otherwise
20// returns an empty scheme or host, clients are not re-directed.
21//
22// Example:
23//
24// r := mux.NewRouter()
25// canonical := handlers.CanonicalHost("http://www.gorillatoolkit.org", 302)
26// r.HandleFunc("/route", YourHandler)
27//
28// log.Fatal(http.ListenAndServe(":7000", canonical(r)))
29func CanonicalHost(domain string, code int) func(h http.Handler) http.Handler {30fn := func(h http.Handler) http.Handler {31return canonical{h, domain, code}32}33
34return fn35}
36
37func (c canonical) ServeHTTP(w http.ResponseWriter, r *http.Request) {38dest, err := url.Parse(c.domain)39if err != nil {40// Call the next handler if the provided domain fails to parse.41c.h.ServeHTTP(w, r)42return43}44
45if dest.Scheme == "" || dest.Host == "" {46// Call the next handler if the scheme or host are empty.47// Note that url.Parse won't fail on in this case.48c.h.ServeHTTP(w, r)49return50}51
52if !strings.EqualFold(cleanHost(r.Host), dest.Host) {53// Re-build the destination URL54dest := dest.Scheme + "://" + dest.Host + r.URL.Path55if r.URL.RawQuery != "" {56dest += "?" + r.URL.RawQuery57}58http.Redirect(w, r, dest, c.code)59return60}61
62c.h.ServeHTTP(w, r)63}
64
65// cleanHost cleans invalid Host headers by stripping anything after '/' or ' '.
66// This is backported from Go 1.5 (in response to issue #11206) and attempts to
67// mitigate malformed Host headers that do not match the format in RFC7230.
68func cleanHost(in string) string {69if i := strings.IndexAny(in, " /"); i != -1 {70return in[:i]71}72return in73}
74