refactor(api): create a new structure for the Go api (#94)

* refactor(api): create a new structure for the Go api

* refactor(api): update the way keyFile parameter is managed

api/handler.go

@@ -0,0 +1,78 @@
+package main
+
+import (
+	"log"
+	"net/http"
+	"net/http/httputil"
+	"net/url"
+	"os"
+)
+
+// newHandler creates a new http.Handler with CSRF protection
+func newHandler(dir string, d string, e string, c Config, tlsFlags TLSFlags) http.Handler {
+	var (
+		mux         = http.NewServeMux()
+		fileHandler = http.FileServer(http.Dir(dir))
+	)
+
+	u, perr := url.Parse(e)
+	if perr != nil {
+		log.Fatal(perr)
+	}
+
+	handler := newAPIHandler(u, tlsFlags)
+	CSRFHandler := newCSRFHandler(d)
+
+	mux.Handle("/dockerapi/", http.StripPrefix("/dockerapi", handler))
+	mux.Handle("/", fileHandler)
+	mux.HandleFunc("/config", func(w http.ResponseWriter, r *http.Request) {
+		configurationHandler(w, r, c)
+	})
+	return CSRFHandler(newCSRFWrapper(mux))
+}
+
+// newAPIHandler initializes a new http.Handler based on the URL scheme
+func newAPIHandler(u *url.URL, tlsFlags TLSFlags) http.Handler {
+	var handler http.Handler
+	if u.Scheme == "tcp" {
+		if tlsFlags.tls {
+			handler = newTCPHandlerWithTLS(u, tlsFlags)
+		} else {
+			handler = newTCPHandler(u)
+		}
+	} else if u.Scheme == "unix" {
+		socketPath := u.Path
+		if _, err := os.Stat(socketPath); err != nil {
+			if os.IsNotExist(err) {
+				log.Fatalf("Unix socket %s does not exist", socketPath)
+			}
+			log.Fatal(err)
+		}
+		handler = newUnixHandler(socketPath)
+	} else {
+		log.Fatalf("Bad Docker enpoint: %s. Only unix:// and tcp:// are supported.", u)
+	}
+	return handler
+}
+
+// newUnixHandler initializes a new UnixHandler
+func newUnixHandler(e string) http.Handler {
+	return &unixHandler{e}
+}
+
+// newTCPHandler initializes a HTTP reverse proxy
+func newTCPHandler(u *url.URL) http.Handler {
+	u.Scheme = "http"
+	return httputil.NewSingleHostReverseProxy(u)
+}
+
+// newTCPHandlerWithL initializes a HTTPS reverse proxy with a TLS configuration
+func newTCPHandlerWithTLS(u *url.URL, tlsFlags TLSFlags) http.Handler {
+	u.Scheme = "https"
+	var tlsConfig = newTLSConfig(tlsFlags)
+	proxy := httputil.NewSingleHostReverseProxy(u)
+	proxy.Transport = &http.Transport{
+		TLSClientConfig: tlsConfig,
+	}
+	return proxy
+}