flathttp/middleware: add content length check with test

flathttp/middleware.go

@@ -0,0 +1,32 @@
+package flathttp
+
+import (
+	"net/http"
+	"strconv"
+)
+
+type Middleware struct {
+	MinContentLength int64 // inclusive
+	MaxContentLength int64 // inclusive
+
+	Accepts []string // content types that are accepted
+}
+
+func (m *Middleware) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	if r.ContentLength <= m.MinContentLength || r.ContentLength >= m.MaxContentLength {
+		tmpl := `{"error": "content length is not acceptable", "given": [[GIVEN]], "min": [[MIN]], "max": [[MAX]]}`
+
+		w.Header().Set("Content-Type", "application/json")
+		w.Header().Set("X-Content-Type-Options", "nosniff")
+		w.WriteHeader(http.StatusBadRequest)
+
+		w.Write(
+			T(tmpl, F{
+				"GIVEN": strconv.FormatInt(r.ContentLength, 10),
+				"MIN":   strconv.FormatInt(m.MinContentLength, 10),
+				"MAX":   strconv.FormatInt(m.MaxContentLength, 10),
+			}),
+		)
+		return
+	}
+}

flathttp/middleware_test.go

@@ -0,0 +1,32 @@
+package flathttp
+
+import (
+	"bytes"
+	"github.com/stretchr/testify/require"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+)
+
+func TestContentLength(t *testing.T) {
+	cases := []struct {
+		given, min, max int64
+		err             bool
+	}{
+		{given: 10, min: 10, max: 100, err: true},
+		{given: 100, min: 10, max: 100, err: true},
+		{given: 11, min: 10, max: 100},
+		{given: 99, min: 10, max: 100},
+	}
+
+	for _, test := range cases {
+		m := &Middleware{MinContentLength: test.min, MaxContentLength: test.max}
+
+		w := httptest.NewRecorder()
+		r := httptest.NewRequest("GET", "/", bytes.NewReader(make([]byte, test.given)))
+		m.ServeHTTP(w, r)
+
+		check := (test.err && w.Code == http.StatusBadRequest) || (!test.err && w.Code == http.StatusOK)
+		require.True(t, check)
+	}
+}

flathttp/server.go

@@ -19,7 +19,7 @@ type Server struct {
 
 	lns  map[string]net.Listener // all listeners
 	wg   sync.WaitGroup          // all served goroutines
-	lm   sync.Mutex              // lifecycle mutex\
+	lm   sync.Mutex              // lifecycle mutex
 	em   sync.Mutex              // errors mutex
 	errs []string                // errors
 }
@@ -83,13 +83,12 @@ func (s *Server) start() error {
 
 	for _, a := range addrs {
 		err := s.listen(a)
-		if err == nil {
-			continue
-		}
-		if errors.Is(err, ErrAlreadyListening) {
-			continue
+		if err != nil {
+			if errors.Is(err, ErrAlreadyListening) {
+				continue
+			}
+			return err
 		}
-		return err
 	}
 
 	return nil

flathttp/utils.go

@@ -0,0 +1,23 @@
+package flathttp
+
+import (
+	"github.com/valyala/fasttemplate"
+	"reflect"
+	"unsafe"
+)
+
+type F map[string]interface{}
+
+func T(tmpl string, fields F) []byte {
+	return B(fasttemplate.ExecuteString(tmpl, "[[", "]]", fields))
+}
+
+func B(s string) []byte {
+	sh := (*reflect.StringHeader)(unsafe.Pointer(&s))
+	bh := reflect.SliceHeader{
+		Data: sh.Data,
+		Len:  sh.Len,
+		Cap:  sh.Len,
+	}
+	return *(*[]byte)(unsafe.Pointer(&bh))
+}

go.mod

@@ -3,8 +3,11 @@ module github.com/lithdew/flatend
 go 1.14
 
 require (
+	github.com/davecgh/go-spew v1.1.0
 	github.com/stretchr/testify v1.4.0
 	github.com/tidwall/gjson v1.6.0 // indirect
+	github.com/tidwall/sjson v1.1.1
+	github.com/valyala/fasttemplate v1.1.0
 	go.uber.org/goleak v1.0.0
 	golang.org/x/lint v0.0.0-20200302205851-738671d3881b // indirect
 	golang.org/x/tools v0.0.0-20200522201501-cb1345f3a375 // indirect

go.sum

@@ -14,6 +14,14 @@ github.com/tidwall/match v1.0.1 h1:PnKP62LPNxHKTwvHHZZzdOAOCtsJTjo6dZLCwpKm5xc=
 github.com/tidwall/match v1.0.1/go.mod h1:LujAq0jyVjBy028G1WhWfIzbpQfMO8bBZ6Tyb0+pL9E=
 github.com/tidwall/pretty v1.0.0 h1:HsD+QiTn7sK6flMKIvNmpqz1qrpP3Ps6jOKIKMooyg4=
 github.com/tidwall/pretty v1.0.0/go.mod h1:XNkn88O1ChpSDQmQeStsy+sBenx6DDtFZJxhVysOjyk=
+github.com/tidwall/pretty v1.0.1 h1:WE4RBSZ1x6McVVC8S/Md+Qse8YUv6HRObAx6ke00NY8=
+github.com/tidwall/pretty v1.0.1/go.mod h1:XNkn88O1ChpSDQmQeStsy+sBenx6DDtFZJxhVysOjyk=
+github.com/tidwall/sjson v1.1.1 h1:7h1vk049Jnd5EH9NyzNiEuwYW4b5qgreBbqRC19AS3U=
+github.com/tidwall/sjson v1.1.1/go.mod h1:yvVuSnpEQv5cYIrO+AT6kw4QVfd5SDZoGIS7/5+fZFs=
+github.com/valyala/bytebufferpool v1.0.0 h1:GqA5TC/0021Y/b9FG4Oi9Mr3q7XYx6KllzawFIhcdPw=
+github.com/valyala/bytebufferpool v1.0.0/go.mod h1:6bBcMArwyJ5K/AmCkWv1jt77kVWyCJ6HpOuEn7z0Csc=
+github.com/valyala/fasttemplate v1.1.0 h1:RZqt0yGBsps8NGvLSGW804QQqCUYYLsaOjTVHy1Ocw4=
+github.com/valyala/fasttemplate v1.1.0/go.mod h1:UQGH1tvbgY+Nz5t2n7tXsz52dQxojPUpymEIMZ47gx8=
 github.com/yuin/goldmark v1.1.27/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=
 go.uber.org/goleak v1.0.0 h1:qsup4IcBdlmsnGfqyLl4Ntn3C2XCCuKAE7DwHpScyUo=
 go.uber.org/goleak v1.0.0/go.mod h1:8a7PlsEVH3e/a/GLqe5IIrQx6GzcnRmZEufDUTk4A7A=