byte to string unsafe conversion in fasthttpadaptor ConvertRequest method (#1375)

* add byte to string unsafe conversion to fasthttpadaptor ConvertRequest method()

* add nosec comment line

* Update fasthttpadaptor/request.go

Co-authored-by: Erik Dubbelboer <erik@dubbelboer.com>

* move unsafe package import next to std packages

* fix lint error in test

Co-authored-by: Erik Dubbelboer <erik@dubbelboer.com>

2 files changed, 42 insertions, 5 deletions

diff --git a/fasthttpadaptor/request.go b/fasthttpadaptor/request.go
index 3f499f8..cc2684b 100644
--- a/fasthttpadaptor/request.go
+++ b/fasthttpadaptor/request.go
@@ -5,28 +5,32 @@ import (
 	"io"
 	"net/http"
 	"net/url"
+	"unsafe"
 
 	"github.com/valyala/fasthttp"
 )
 
 // ConvertRequest convert a fasthttp.Request to an http.Request
 // forServer should be set to true when the http.Request is going to passed to a http.Handler.
+//
+// The http.Request must not be used after the fasthttp handler has returned!
+// Memory in use by the http.Request will be reused after your handler has returned!
 func ConvertRequest(ctx *fasthttp.RequestCtx, r *http.Request, forServer bool) error {
 	body := ctx.PostBody()
-	strRequestURI := string(ctx.RequestURI())
+	strRequestURI := b2s(ctx.RequestURI())
 
 	rURL, err := url.ParseRequestURI(strRequestURI)
 	if err != nil {
 		return err
 	}
 
-	r.Method = string(ctx.Method())
+	r.Method = b2s(ctx.Method())
 	r.Proto = "HTTP/1.1"
 	r.ProtoMajor = 1
 	r.ProtoMinor = 1
 	r.ContentLength = int64(len(body))
 	r.RemoteAddr = ctx.RemoteAddr().String()
-	r.Host = string(ctx.Host())
+	r.Host = b2s(ctx.Host())
 	r.TLS = ctx.TLSConnectionState()
 	r.Body = io.NopCloser(bytes.NewReader(body))
 	r.URL = rURL
@@ -44,8 +48,8 @@ func ConvertRequest(ctx *fasthttp.RequestCtx, r *http.Request, forServer bool) e
 	}
 
 	ctx.Request.Header.VisitAll(func(k, v []byte) {
-		sk := string(k)
-		sv := string(v)
+		sk := b2s(k)
+		sv := b2s(v)
 
 		switch sk {
 		case "Transfer-Encoding":
@@ -57,3 +61,8 @@ func ConvertRequest(ctx *fasthttp.RequestCtx, r *http.Request, forServer bool) e
 
 	return nil
 }
+
+func b2s(b []byte) string {
+	/* #nosec G103 */
+	return *(*string)(unsafe.Pointer(&b))
+}
diff --git a/fasthttpadaptor/request_test.go b/fasthttpadaptor/request_test.go
new file mode 100644
index 0000000..3b6ba54
--- /dev/null
+++ b/fasthttpadaptor/request_test.go
@@ -0,0 +1,28 @@
+package fasthttpadaptor
+
+import (
+	"github.com/valyala/fasthttp"
+	"net/http"
+	"testing"
+)
+
+func BenchmarkConvertRequest(b *testing.B) {
+	var httpReq http.Request
+
+	ctx := &fasthttp.RequestCtx{
+		Request: fasthttp.Request{
+			Header:        fasthttp.RequestHeader{},
+			UseHostHeader: false,
+		},
+	}
+	ctx.Request.Header.SetMethod("GET")
+	ctx.Request.Header.Set("x", "test")
+	ctx.Request.Header.Set("y", "test")
+	ctx.Request.SetRequestURI("/test")
+	ctx.Request.SetHost("test")
+	b.ResetTimer()
+
+	for i := 0; i < b.N; i++ {
+		_ = ConvertRequest(ctx, &httpReq, true)
+	}
+}