Remove all leading and trailing whitespace

accept.go

+//go:build !js
 // +build !js
 
 package websocket
@@ -185,6 +186,8 @@ func verifyClientRequest(w http.ResponseWriter, r *http.Request) (errCode int, _
 	}
 
 	websocketSecKey := r.Header.Get("Sec-WebSocket-Key")
+	// The RFC states to remove any leading or trailing whitespace.
+	websocketSecKey = strings.TrimSpace(websocketSecKey)
 	if websocketSecKey == "" {
 		return http.StatusBadRequest, errors.New("WebSocket protocol violation: missing Sec-WebSocket-Key")
 	}

accept_test.go

+//go:build !js
 // +build !js
 
 package websocket
@@ -229,6 +230,16 @@ func Test_verifyClientHandshake(t *testing.T) {
 			},
 			success: true,
 		},
+		{
+			name: "successSecKeyExtraSpace",
+			h: map[string]string{
+				"Connection":            "keep-alive, Upgrade",
+				"Upgrade":               "websocket",
+				"Sec-WebSocket-Version": "13",
+				"Sec-WebSocket-Key":     "   " + xrand.Base64(16) + "  ",
+			},
+			success: true,
+		},
 	}
 
 	for _, tc := range testCases {