Validate http requests based on openapi spec

openapi.go

type ValidationInterceptor struct {
	router http.Handler
	val    routers.Router
}

func (s *ValidationInterceptor) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	route, pathParams, err := s.val.FindRoute(r)
	if err != nil {
		log.Printf("no route: %v", err)
		w.WriteHeader(http.StatusNotFound)
		return
	}

	requestValidationInput := &openapi3filter.RequestValidationInput{
		Request:    r,
		PathParams: pathParams,
		Route:      route,
	}

	err = openapi3filter.ValidateRequest(r.Context(), requestValidationInput)
	if err != nil {
		log.Printf("invalid request: %v", err)
		w.WriteHeader(http.StatusBadRequest)
		return
	}

	var (
		statusCode = 200
		body       = new(bytes.Buffer)
	)

	wrapped := httpsnoop.Wrap(w, httpsnoop.Hooks{
		WriteHeader: func(whf httpsnoop.WriteHeaderFunc) httpsnoop.WriteHeaderFunc {
			return func(code int) {
				statusCode = code
			}
		},
		Write: func(wf httpsnoop.WriteFunc) httpsnoop.WriteFunc {
			return func(b []byte) (int, error) {
				return body.Write(b)
			}
		},
	})

	s.router.ServeHTTP(wrapped, r)

	responseValidationInput := &openapi3filter.ResponseValidationInput{
		RequestValidationInput: requestValidationInput,
		Status:                 statusCode,
		Header:                 w.Header(),
	}

	responseValidationInput.SetBodyBytes(body.Bytes())

	err = openapi3filter.ValidateResponse(r.Context(), responseValidationInput)
	if err != nil {
		log.Printf("invalid response: %v", err)
		w.WriteHeader(http.StatusInternalServerError)
		return
	}

	w.WriteHeader(statusCode)
	io.Copy(w, body)

}