portainer/portainer

package file

import (
    "net/http"
    "strings"

    "github.com/gorilla/handlers"
)

// Handler represents an HTTP API handler for managing static files.
type Handler struct {
    http.Handler
    wasInstanceDisabled func() bool
}

// NewHandler creates a handler to serve static files.
func NewHandler(assetPublicPath string, wasInstanceDisabled func() bool) *Handler {
    h := &Handler{
        Handler: handlers.CompressHandler(
            http.FileServer(http.Dir(assetPublicPath)),
        ),
        wasInstanceDisabled: wasInstanceDisabled,
    }

    return h
}

func isHTML(acceptContent []string) bool {
    for _, accept := range acceptContent {
        if strings.Contains(accept, "text/html") {
            return true
        }
    }
    return false
}

func (handler *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
    if handler.wasInstanceDisabled() {
        if r.RequestURI == "/" || r.RequestURI == "/index.html" {
            http.Redirect(w, r, "/timeout.html", http.StatusTemporaryRedirect)
            return
        }
    } else {
        if strings.HasPrefix(r.RequestURI, "/timeout.html") {
            http.Redirect(w, r, "/", http.StatusTemporaryRedirect)
            return
        }
    }

    if !isHTML(r.Header["Accept"]) {
        w.Header().Set("Cache-Control", "max-age=31536000")
    } else {
        w.Header().Set("Cache-Control", "no-cache, no-store, must-revalidate")
    }

    w.Header().Add("X-XSS-Protection", "1; mode=block")
    w.Header().Add("X-Content-Type-Options", "nosniff")
    handler.Handler.ServeHTTP(w, r)
}