Add support for HEAD and fix OPTIONS HTTP method

httpbin/handlers_test.go

@@ -192,6 +192,27 @@ func TestGet(t *testing.T) {
 	}
 }
 
+func TestHEAD(t *testing.T) {
+	r, _ := http.NewRequest("HEAD", "/", nil)
+	w := httptest.NewRecorder()
+	handler.ServeHTTP(w, r)
+
+	assertStatusCode(t, w, 200)
+	assertBodyEquals(t, w, "")
+
+	contentLengthStr := w.HeaderMap.Get("Content-Length")
+	if contentLengthStr == "" {
+		t.Fatalf("missing Content-Length header in response")
+	}
+	contentLength, err := strconv.Atoi(contentLengthStr)
+	if err != nil {
+		t.Fatalf("error converting Content-Lengh %v to integer: %s", contentLengthStr, err)
+	}
+	if contentLength <= 0 {
+		t.Fatalf("Content-Lengh %v should be greater than 0", contentLengthStr)
+	}
+}
+
 func TestCORS(t *testing.T) {
 	t.Run("CORS/no_request_origin", func(t *testing.T) {
 		r, _ := http.NewRequest("GET", "/get", nil)
@@ -213,13 +234,15 @@ func TestCORS(t *testing.T) {
 		w := httptest.NewRecorder()
 		handler.ServeHTTP(w, r)
 
+		assertStatusCode(t, w, 200)
+
 		var headerTests = []struct {
 			key      string
 			expected string
 		}{
 			{"Access-Control-Allow-Origin", "*"},
 			{"Access-Control-Allow-Credentials", "true"},
-			{"Access-Control-Allow-Methods", "GET, POST, PUT, DELETE, PATCH, OPTIONS"},
+			{"Access-Control-Allow-Methods", "GET, POST, HEAD, PUT, DELETE, PATCH, OPTIONS"},
 			{"Access-Control-Max-Age", "3600"},
 			{"Access-Control-Allow-Headers", ""},
 		}
@@ -234,6 +257,8 @@ func TestCORS(t *testing.T) {
 		w := httptest.NewRecorder()
 		handler.ServeHTTP(w, r)
 
+		assertStatusCode(t, w, 200)
+
 		var headerTests = []struct {
 			key      string
 			expected string

httpbin/helpers.go

@@ -27,6 +27,16 @@ func getRequestHeaders(r *http.Request) http.Header {
 	return h
 }
 
+// Copies all headers from src to dst
+// From https://golang.org/src/net/http/httputil/reverseproxy.go#L109
+func copyHeader(dst, src http.Header) {
+	for k, vv := range src {
+		for _, v := range vv {
+			dst.Add(k, v)
+		}
+	}
+}
+
 func getOrigin(r *http.Request) string {
 	origin := r.Header.Get("X-Forwarded-For")
 	if origin == "" {

httpbin/httpbin.go

@@ -175,6 +175,7 @@ func (h *HTTPBin) Handler() http.Handler {
 	handler = mux
 	handler = limitRequestSize(h.options.MaxMemory, handler)
 	handler = logger(handler)
+	handler = optionsAndHead(handler)
 	handler = cors(handler)
 	return handler
 }

httpbin/middleware.go

@@ -4,9 +4,33 @@ import (
 	"fmt"
 	"log"
 	"net/http"
+	"net/http/httptest"
 	"time"
 )
 
+func optionsAndHead(h http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		switch r.Method {
+		case "OPTIONS":
+			w.Header().Set("Access-Control-Allow-Methods", "GET, POST, HEAD, PUT, DELETE, PATCH, OPTIONS")
+			w.Header().Set("Access-Control-Max-Age", "3600")
+			if r.Header.Get("Access-Control-Request-Headers") != "" {
+				w.Header().Set("Access-Control-Allow-Headers", r.Header.Get("Access-Control-Request-Headers"))
+			}
+			w.WriteHeader(200)
+		case "HEAD":
+			rwRec := httptest.NewRecorder()
+			r.Method = "GET"
+			h.ServeHTTP(rwRec, r)
+
+			copyHeader(w.Header(), rwRec.Header())
+			w.WriteHeader(rwRec.Code)
+		default:
+			h.ServeHTTP(w, r)
+		}
+	})
+}
+
 func cors(h http.Handler) http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		origin := r.Header.Get("Origin")
@@ -17,13 +41,6 @@ func cors(h http.Handler) http.Handler {
 		respHeader.Set("Access-Control-Allow-Origin", origin)
 		respHeader.Set("Access-Control-Allow-Credentials", "true")
 
-		if r.Method == "OPTIONS" {
-			respHeader.Set("Access-Control-Allow-Methods", "GET, POST, PUT, DELETE, PATCH, OPTIONS")
-			respHeader.Set("Access-Control-Max-Age", "3600")
-			if r.Header.Get("Access-Control-Request-Headers") != "" {
-				respHeader.Set("Access-Control-Allow-Headers", r.Header.Get("Access-Control-Request-Headers"))
-			}
-		}
 		h.ServeHTTP(w, r)
 	})
 }