github.com/hxx258456/ccgo@v0.0.5-0.20230213014102-48b35f46f66f/handlers/canonical.go (about)

     1  package handlers
     2  
     3  import (
     4  	"net/url"
     5  	"strings"
     6  
     7  	http "github.com/hxx258456/ccgo/gmhttp"
     8  )
     9  
    10  type canonical struct {
    11  	h      http.Handler
    12  	domain string
    13  	code   int
    14  }
    15  
    16  // CanonicalHost is HTTP middleware that re-directs requests to the canonical
    17  // domain. It accepts a domain and a status code (e.g. 301 or 302) and
    18  // re-directs clients to this domain. The existing request path is maintained.
    19  //
    20  // Note: If the provided domain is considered invalid by url.Parse or otherwise
    21  // returns an empty scheme or host, clients are not re-directed.
    22  //
    23  // Example:
    24  //
    25  //  r := mux.NewRouter()
    26  //  canonical := handlers.CanonicalHost("http://www.gorillatoolkit.org", 302)
    27  //  r.HandleFunc("/route", YourHandler)
    28  //
    29  //  log.Fatal(http.ListenAndServe(":7000", canonical(r)))
    30  //
    31  func CanonicalHost(domain string, code int) func(h http.Handler) http.Handler {
    32  	fn := func(h http.Handler) http.Handler {
    33  		return canonical{h, domain, code}
    34  	}
    35  
    36  	return fn
    37  }
    38  
    39  func (c canonical) ServeHTTP(w http.ResponseWriter, r *http.Request) {
    40  	dest, err := url.Parse(c.domain)
    41  	if err != nil {
    42  		// Call the next handler if the provided domain fails to parse.
    43  		c.h.ServeHTTP(w, r)
    44  		return
    45  	}
    46  
    47  	if dest.Scheme == "" || dest.Host == "" {
    48  		// Call the next handler if the scheme or host are empty.
    49  		// Note that url.Parse won't fail on in this case.
    50  		c.h.ServeHTTP(w, r)
    51  		return
    52  	}
    53  
    54  	if !strings.EqualFold(cleanHost(r.Host), dest.Host) {
    55  		// Re-build the destination URL
    56  		dest := dest.Scheme + "://" + dest.Host + r.URL.Path
    57  		if r.URL.RawQuery != "" {
    58  			dest += "?" + r.URL.RawQuery
    59  		}
    60  		http.Redirect(w, r, dest, c.code)
    61  		return
    62  	}
    63  
    64  	c.h.ServeHTTP(w, r)
    65  }
    66  
    67  // cleanHost cleans invalid Host headers by stripping anything after '/' or ' '.
    68  // This is backported from Go 1.5 (in response to issue #11206) and attempts to
    69  // mitigate malformed Host headers that do not match the format in RFC7230.
    70  func cleanHost(in string) string {
    71  	if i := strings.IndexAny(in, " /"); i != -1 {
    72  		return in[:i]
    73  	}
    74  	return in
    75  }