package middleware import ( "bufio" "compress/gzip" "io" "io/ioutil" "net" "net/http" "strings" "sync" "github.com/labstack/echo/v4" ) type ( // GzipConfig defines the config for Gzip middleware. GzipConfig struct { // Skipper defines a function to skip middleware. Skipper Skipper // Gzip compression level. // Optional. Default value -1. Level int `yaml:"level"` } gzipResponseWriter struct { io.Writer http.ResponseWriter wroteBody bool } ) const ( gzipScheme = "gzip" ) var ( // DefaultGzipConfig is the default Gzip middleware config. DefaultGzipConfig = GzipConfig{ Skipper: DefaultSkipper, Level: -1, } ) // Gzip returns a middleware which compresses HTTP response using gzip compression // scheme. func Gzip() echo.MiddlewareFunc { return GzipWithConfig(DefaultGzipConfig) } // GzipWithConfig return Gzip middleware with config. // See: `Gzip()`. func GzipWithConfig(config GzipConfig) echo.MiddlewareFunc { // Defaults if config.Skipper == nil { config.Skipper = DefaultGzipConfig.Skipper } if config.Level == 0 { config.Level = DefaultGzipConfig.Level } pool := gzipCompressPool(config) return func(next echo.HandlerFunc) echo.HandlerFunc { return func(c echo.Context) error { if config.Skipper(c) { return next(c) } res := c.Response() res.Header().Add(echo.HeaderVary, echo.HeaderAcceptEncoding) if strings.Contains(c.Request().Header.Get(echo.HeaderAcceptEncoding), gzipScheme) { res.Header().Set(echo.HeaderContentEncoding, gzipScheme) // Issue #806 i := pool.Get() w, ok := i.(*gzip.Writer) if !ok { return echo.NewHTTPError(http.StatusInternalServerError, i.(error).Error()) } rw := res.Writer w.Reset(rw) grw := &gzipResponseWriter{Writer: w, ResponseWriter: rw} defer func() { if !grw.wroteBody { if res.Header().Get(echo.HeaderContentEncoding) == gzipScheme { res.Header().Del(echo.HeaderContentEncoding) } // We have to reset response to it's pristine state when // nothing is written to body or error is returned. // See issue #424, #407. res.Writer = rw w.Reset(ioutil.Discard) } w.Close() pool.Put(w) }() res.Writer = grw } return next(c) } } } func (w *gzipResponseWriter) WriteHeader(code int) { w.Header().Del(echo.HeaderContentLength) // Issue #444 w.ResponseWriter.WriteHeader(code) } func (w *gzipResponseWriter) Write(b []byte) (int, error) { if w.Header().Get(echo.HeaderContentType) == "" { w.Header().Set(echo.HeaderContentType, http.DetectContentType(b)) } w.wroteBody = true return w.Writer.Write(b) } func (w *gzipResponseWriter) Flush() { w.Writer.(*gzip.Writer).Flush() if flusher, ok := w.ResponseWriter.(http.Flusher); ok { flusher.Flush() } } func (w *gzipResponseWriter) Hijack() (net.Conn, *bufio.ReadWriter, error) { return w.ResponseWriter.(http.Hijacker).Hijack() } func (w *gzipResponseWriter) Push(target string, opts *http.PushOptions) error { if p, ok := w.ResponseWriter.(http.Pusher); ok { return p.Push(target, opts) } return http.ErrNotSupported } func gzipCompressPool(config GzipConfig) sync.Pool { return sync.Pool{ New: func() interface{} { w, err := gzip.NewWriterLevel(ioutil.Discard, config.Level) if err != nil { return err } return w }, } }