Added ability to filter out non-GET requests

Author: valyala

doc.go

@@ -21,6 +21,7 @@ Fasthttp provides the following features:
         * Maximum request body size.
         * Maximum request execution time.
         * Maximum keep-alive connection lifetime.
+        * Early filtering out non-GET requests.
 
     * A lot of additional useful info is exposed to request handler:
 

http.go

@@ -42,14 +42,14 @@ type Response struct {
 	// Copying Header by value is forbidden. Use pointer to Header instead.
 	Header ResponseHeader
 
+	// Response.Read() skips reading body if set to true.
+	// Use it for HEAD requests.
+	SkipBody bool
+
 	body []byte
 	w    responseBodyWriter
 
 	bodyStream io.Reader
-
-	// If set to true, Response.Read() skips reading body.
-	// Use it for HEAD requests.
-	SkipBody bool
 }
 
 // SetRequestURI sets RequestURI.
@@ -307,6 +307,8 @@ func (req *Request) Read(r *bufio.Reader) error {
 
 const defaultMaxInMemoryFileSize = 16 * 1024 * 1024
 
+var errGetOnly = errors.New("non-GET request received")
+
 // ReadLimitBody reads request from the given r, limiting the body size.
 //
 // If maxBodySize > 0 and the body size exceeds maxBodySize,
@@ -316,11 +318,18 @@ const defaultMaxInMemoryFileSize = 16 * 1024 * 1024
 // reading multipart/form-data request in order to delete temporarily
 // uploaded files.
 func (req *Request) ReadLimitBody(r *bufio.Reader, maxBodySize int) error {
+	return req.readLimitBody(r, maxBodySize, false)
+}
+
+func (req *Request) readLimitBody(r *bufio.Reader, maxBodySize int, getOnly bool) error {
 	req.clearSkipHeader()
 	err := req.Header.Read(r)
 	if err != nil {
 		return err
 	}
+	if getOnly && !req.Header.IsGet() {
+		return errGetOnly
+	}
 
 	if req.Header.IsPost() || req.Header.IsPut() {
 		contentLength := req.Header.ContentLength()

server.go

@@ -163,6 +163,15 @@ type Server struct {
 	// Aggressive memory usage reduction is disabled by default.
 	ReduceMemoryUsage bool
 
+	// Rejects all non-GET requests if set to true.
+	//
+	// This option is useful as anti-DoS protection for servers
+	// accepting only GET requests. When set the request size is limited
+	// by ReadBufferSize.
+	//
+	// Server accepts all the requests by default.
+	GetOnly bool
+
 	// Logger, which is used by RequestCtx.Logger().
 	//
 	// By default standard logger from log package is used.
@@ -869,7 +878,7 @@ func (s *Server) serveConn(c net.Conn) error {
 			if br == nil {
 				br = acquireReader(ctx)
 			}
-			err = ctx.Request.ReadLimitBody(br, s.MaxRequestBodySize)
+			err = ctx.Request.readLimitBody(br, s.MaxRequestBodySize, s.GetOnly)
 			if br.Buffered() == 0 || err != nil {
 				releaseReader(s, br)
 				br = nil

server_test.go

@@ -126,6 +126,44 @@ func TestTimeoutHandlerSuccess(t *testing.T) {
 	verifyResponse(t, br, StatusOK, "aaa/bbb", "real response")
 }
 
+func TestServerGetOnly(t *testing.T) {
+	h := func(ctx *RequestCtx) {
+		if !ctx.IsGet() {
+			t.Fatalf("non-get request: %q", ctx.Method())
+		}
+		ctx.Success("foo/bar", []byte("success"))
+	}
+	s := &Server{
+		Handler: h,
+		GetOnly: true,
+	}
+
+	rw := &readWriter{}
+	rw.r.WriteString("POST /foo HTTP/1.1\r\nHost: google.com\r\nContent-Length: 5\r\nContent-Type: aaa\r\n\r\n12345")
+
+	ch := make(chan error)
+	go func() {
+		ch <- s.ServeConn(rw)
+	}()
+
+	select {
+	case err := <-ch:
+		if err == nil {
+			t.Fatalf("expecting error")
+		}
+		if err != errGetOnly {
+			t.Fatalf("Unexpected error from serveConn: %s. Expecting %s", err, errGetOnly)
+		}
+	case <-time.After(100 * time.Millisecond):
+		t.Fatalf("timeout")
+	}
+
+	resp := rw.w.Bytes()
+	if len(resp) > 0 {
+		t.Fatalf("unexpected response %q. Expecting zero", resp)
+	}
+}
+
 func TestTimeoutHandlerTimeout(t *testing.T) {
 	h := func(ctx *RequestCtx) {
 		time.Sleep(time.Second)