Use IndexByte instead of Split to reduce memory allocation and improve performance

Author: yonbiaoxiao

context.go

@@ -276,7 +276,12 @@ func (c *context) RealIP() string {
 	}
 	// Fall back to legacy behavior
 	if ip := c.request.Header.Get(HeaderXForwardedFor); ip != "" {
-		return strings.Split(ip, ", ")[0]
+		i := strings.IndexAny(ip, ", ")
+		if i > 0 {
+			return ip[:i]
+		} else {
+			return ip
+		}
 	}
 	if ip := c.request.Header.Get(HeaderXRealIP); ip != "" {
 		return ip

context_test.go

@@ -871,3 +871,12 @@ func TestContext_RealIP(t *testing.T) {
 		testify.Equal(t, tt.s, tt.c.RealIP())
 	}
 }
+
+func BenchmarkRealIPForHeaderXForwardFor(b *testing.B) {
+	c := context{request: &http.Request{
+		Header: http.Header{HeaderXForwardedFor: []string{"127.0.0.1, 127.0.1.1, "}},
+	}}
+	for i := 0; i < b.N; i++ {
+		c.RealIP()
+	}
+}