host_serve_mux.go

package tigertonic

import (
	"log"
	"net/http"
	"strings"
)

// HostServeMux is an HTTP request multiplexer that implements http.Handler
// with an API similar to http.ServeMux.  It is only sensitive to the hostname
// and doesn't even look at the rest of the request.
type HostServeMux map[string]http.Handler

// NewHostServeMux makes a new HostServeMux.
func NewHostServeMux() HostServeMux {
	return make(HostServeMux)
}

// Handle registers an http.Handler for the given hostname.
func (mux HostServeMux) Handle(hostname string, handler http.Handler) {
	log.Printf("handling %s\n", hostname)
	mux[hostname] = handler
}

// HandleFunc registers a handler function for the given hostname.
func (mux HostServeMux) HandleFunc(hostname string, handler func(http.ResponseWriter, *http.Request)) {
	mux.Handle(hostname, http.HandlerFunc(handler))
}

// Handler returns the handler to use for the given HTTP request.
func (mux HostServeMux) Handler(r *http.Request) (http.Handler, string) {
	host := stripPortFromHost(r.Host)
	if handler, ok := mux[host]; ok {
		return handler, r.Host
	}
	host = stripPortFromHost(r.URL.Host)
	if handler, ok := mux[host]; ok {
		return handler, r.URL.Host
	}
	return NotFoundHandler{}, ""
}

// ServeHTTP routes an HTTP request to the http.Handler registered for the
// requested hostname.  It responds 404 if the hostname is not registered.
func (mux HostServeMux) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	handler, _ := mux.Handler(r)
	handler.ServeHTTP(w, r)
}

// Given that we know that the port in the URL was correct, otherwise we
// wouldn't be hitting the service, we can strip the port and use it to locate
// the hostname in the hostname map.
func stripPortFromHost(host string) string {
	if colon := strings.LastIndex(host, ":"); colon >= 0 {
		host = host[:colon]
	}
	return host
}