fix: match request media types case-insensitively

bind.go

@@ -61,6 +61,7 @@ func BindQueryParams(c *Context, target any) error {
 }
 
 // BindBody binds request body contents to bindable object
+// The Content-Type media type is matched case-insensitively.
 // NB: then binding forms take note that this implementation uses standard library form parsing
 // which parses form data from BOTH URL and BODY if content type is not MIMEMultipartForm
 // See non-MIMEMultipartForm: https://golang.org/pkg/net/http/#Request.ParseForm
@@ -71,9 +72,9 @@ func BindBody(c *Context, target any) (err error) {
 		return
 	}
 
-	// mediatype is found like `mime.ParseMediaType()` does it
+	// Like mime.ParseMediaType, normalize the media type without changing its parameters.
 	base, _, _ := strings.Cut(req.Header.Get(HeaderContentType), ";")
-	mediatype := strings.TrimSpace(base)
+	mediatype := strings.ToLower(strings.TrimSpace(base))
 
 	switch mediatype {
 	case MIMEApplicationJSON:

bind_test.go

@@ -208,6 +208,49 @@ func TestBindJSON(t *testing.T) {
 	testBindError(t, strings.NewReader(userJSONInvalidType), MIMEApplicationJSON, &json.UnmarshalTypeError{})
 }
 
+func TestBindBodyMediaTypeCaseInsensitive(t *testing.T) {
+	body := new(bytes.Buffer)
+	mw := multipart.NewWriter(body)
+	if !assert.NoError(t, mw.SetBoundary("CaseSensitiveBoundary")) {
+		return
+	}
+	assert.NoError(t, mw.WriteField("id", "1"))
+	assert.NoError(t, mw.WriteField("name", "Jon Snow"))
+	assert.NoError(t, mw.Close())
+
+	for _, tc := range []struct {
+		contentType string
+		body        string
+	}{
+		{"Application/JSON; Charset=UTF-8", userJSON},
+		{"APPLICATION/XML", userXML},
+		{"Text/XML; charset=UTF-8", userXML},
+		{"Application/X-Www-Form-Urlencoded", userForm},
+		{"Multipart/Form-Data; boundary=CaseSensitiveBoundary", body.String()},
+	} {
+		t.Run(tc.contentType, func(t *testing.T) {
+			req := httptest.NewRequest(http.MethodPost, "/", strings.NewReader(tc.body))
+			req.Header.Set(HeaderContentType, tc.contentType)
+			c := New().NewContext(req, httptest.NewRecorder())
+			var target user
+
+			if assert.NoError(t, BindBody(c, &target)) {
+				assert.Equal(t, user{ID: 1, Name: "Jon Snow"}, target)
+			}
+			assert.Equal(t, tc.contentType, req.Header.Get(HeaderContentType))
+		})
+	}
+
+	t.Run("unsupported media type", func(t *testing.T) {
+		req := httptest.NewRequest(http.MethodPost, "/", strings.NewReader(userJSON))
+		req.Header.Set(HeaderContentType, "Application/JSON-Invalid")
+		c := New().NewContext(req, httptest.NewRecorder())
+		var target user
+
+		assert.Equal(t, &HTTPError{Code: http.StatusUnsupportedMediaType}, BindBody(c, &target))
+	})
+}
+
 func TestBindXML(t *testing.T) {
 	testBindOkay(t, strings.NewReader(userXML), nil, MIMEApplicationXML)
 	testBindOkay(t, strings.NewReader(userXML), dummyQuery, MIMEApplicationXML)

context.go

@@ -409,7 +409,8 @@ func (c *Context) FormValueOr(name, defaultValue string) string {
 
 // FormValues returns the form field values as `url.Values`.
 func (c *Context) FormValues() (url.Values, error) {
-	if strings.HasPrefix(c.request.Header.Get(HeaderContentType), MIMEMultipartForm) {
+	base, _, _ := strings.Cut(c.request.Header.Get(HeaderContentType), ";")
+	if strings.EqualFold(strings.TrimSpace(base), MIMEMultipartForm) {
 		if err := c.request.ParseMultipartForm(c.formParseMaxMemory); err != nil {
 			return nil, err
 		}

context_test.go

@@ -816,6 +816,34 @@ func TestContextFormValue(t *testing.T) {
 	assert.Error(t, err)
 }
 
+func TestContextFormValuesMediaTypeCaseInsensitive(t *testing.T) {
+	body := new(bytes.Buffer)
+	mw := multipart.NewWriter(body)
+	if !assert.NoError(t, mw.SetBoundary("CaseSensitiveBoundary")) {
+		return
+	}
+	assert.NoError(t, mw.WriteField("name", "Jon Snow"))
+	assert.NoError(t, mw.Close())
+
+	for _, contentType := range []string{
+		"multipart/form-data; boundary=CaseSensitiveBoundary",
+		"Multipart/Form-Data; boundary=CaseSensitiveBoundary",
+		"MULTIPART/FORM-DATA; boundary=CaseSensitiveBoundary",
+	} {
+		t.Run(contentType, func(t *testing.T) {
+			req := httptest.NewRequest(http.MethodPost, "/?query=value", bytes.NewReader(body.Bytes()))
+			req.Header.Set(HeaderContentType, contentType)
+			c := New().NewContext(req, nil)
+
+			values, err := c.FormValues()
+			if assert.NoError(t, err) {
+				assert.Equal(t, url.Values{"name": {"Jon Snow"}, "query": {"value"}}, values)
+			}
+			assert.Equal(t, contentType, req.Header.Get(HeaderContentType))
+		})
+	}
+}
+
 func TestContext_QueryParams(t *testing.T) {
 	var testCases = []struct {
 		expect   url.Values