Adding sync.Pool to Decompress middleware

Fixing a http.Request.Body leak on the decompress middleware that were
not properly Close
Removing the defer on the call to gzip.Reader, because that reader is
already exausted after the call to io.Copy

Author: pafuent

middleware/compress.go

@@ -59,7 +59,7 @@ func GzipWithConfig(config GzipConfig) echo.MiddlewareFunc {
 		config.Level = DefaultGzipConfig.Level
 	}
 
-	pool := gzipPool(config)
+	pool := gzipCompressPool(config)
 
 	return func(next echo.HandlerFunc) echo.HandlerFunc {
 		return func(c echo.Context) error {
@@ -133,7 +133,7 @@ func (w *gzipResponseWriter) Push(target string, opts *http.PushOptions) error {
 	return http.ErrNotSupported
 }
 
-func gzipPool(config GzipConfig) sync.Pool {
+func gzipCompressPool(config GzipConfig) sync.Pool {
 	return sync.Pool{
 		New: func() interface{} {
 			w, err := gzip.NewWriterLevel(ioutil.Discard, config.Level)

middleware/decompress.go

@@ -3,9 +3,12 @@ package middleware
 import (
 	"bytes"
 	"compress/gzip"
-	"github.com/labstack/echo/v4"
 	"io"
 	"io/ioutil"
+	"net/http"
+	"sync"
+
+	"github.com/labstack/echo/v4"
 )
 
 type (
@@ -32,27 +35,63 @@ func Decompress() echo.MiddlewareFunc {
 //DecompressWithConfig decompresses request body based if content encoding type is set to "gzip" with config
 func DecompressWithConfig(config DecompressConfig) echo.MiddlewareFunc {
 	return func(next echo.HandlerFunc) echo.HandlerFunc {
+		pool := gzipDecompressPool()
 		return func(c echo.Context) error {
 			if config.Skipper(c) {
 				return next(c)
 			}
 			switch c.Request().Header.Get(echo.HeaderContentEncoding) {
 			case GZIPEncoding:
-				gr, err := gzip.NewReader(c.Request().Body)
-				if err != nil {
+				b := c.Request().Body
+
+				i := pool.Get()
+				gr, ok := i.(*gzip.Reader)
+				if !ok {
+					return echo.NewHTTPError(http.StatusInternalServerError, i.(error).Error())
+				}
+
+				if err := gr.Reset(b); err != nil {
+					pool.Put(gr)
 					if err == io.EOF { //ignore if body is empty
 						return next(c)
 					}
 					return err
 				}
-				defer gr.Close()
 				var buf bytes.Buffer
 				io.Copy(&buf, gr)
+
+				gr.Close()
+				pool.Put(gr)
+
+				b.Close() // http.Request.Body is closed by the Server, but because we are replacing it, it must be closed here
+
 				r := ioutil.NopCloser(&buf)
-				defer r.Close()
 				c.Request().Body = r
 			}
 			return next(c)
 		}
 	}
 }
+
+func gzipDecompressPool() sync.Pool {
+	return sync.Pool{
+		New: func() interface{} {
+			// create with an empty reader (but with GZIP header)
+			w, err := gzip.NewWriterLevel(ioutil.Discard, gzip.BestSpeed)
+			if err != nil {
+				return err
+			}
+
+			b := new(bytes.Buffer)
+			w.Reset(b)
+			w.Flush()
+			w.Close()
+
+			r, err := gzip.NewReader(bytes.NewReader(b.Bytes()))
+			if err != nil {
+				return err
+			}
+			return r
+		},
+	}
+}