From da2cc385dbfd887a5476317df538a41508aad0a2 Mon Sep 17 00:00:00 2001
From: Volodymyr Dorokhov <volodymyr@cloudflare.com>
Date: Thu, 28 Jan 2021 11:12:14 +0000
Subject: [PATCH] Fix body nil checking in NewRequest

NewRequest accepts interface{} as body argument
but doesn't check it on nil properly. It should
check that not only variable is nil, but also pointer
value is nil. Otherwise it constructs different
Request objects for the same parameters. Tests are
added.
---
 client.go      |  9 +++++++++
 client_test.go | 18 ++++++++++++++++++
 2 files changed, 27 insertions(+)

diff --git a/client.go b/client.go
index 79dc931..4332060 100644
--- a/client.go
+++ b/client.go
@@ -34,6 +34,7 @@ import (
 	"net/http"
 	"net/url"
 	"os"
+	"reflect"
 	"regexp"
 	"strconv"
 	"strings"
@@ -154,6 +155,10 @@ func getBodyReaderAndContentLength(rawBody interface{}) (ReaderFunc, int64, erro
 	var bodyReader ReaderFunc
 	var contentLength int64
 
+	if isNil(rawBody) {
+		return bodyReader, contentLength, nil
+	}
+
 	switch body := rawBody.(type) {
 	// If they gave us a function already, great! Use it.
 	case ReaderFunc:
@@ -772,3 +777,7 @@ func (c *Client) StandardClient() *http.Client {
 		Transport: &RoundTripper{Client: c},
 	}
 }
+
+func isNil(v interface{}) bool {
+	return v == nil || ((reflect.ValueOf(v).Kind() == reflect.Ptr || reflect.ValueOf(v).Kind() == reflect.Slice) && reflect.ValueOf(v).IsNil())
+}
diff --git a/client_test.go b/client_test.go
index b8a3d9d..df63726 100644
--- a/client_test.go
+++ b/client_test.go
@@ -842,3 +842,21 @@ func TestClient_StandardClient(t *testing.T) {
 		t.Fatalf("expected %v, got %v", client, v)
 	}
 }
+
+func Test_NewRequest(t *testing.T) {
+	req, err := NewRequest("GET", "localhost:1234", nil)
+	if err != nil {
+		t.Fatalf("failed to create a request: %s", err)
+	}
+
+	var b []byte
+	b = nil
+	r, err := NewRequest("GET", "localhost:1234", b)
+	if err != nil {
+		t.Fatalf("failed to create a request: %s", err)
+	}
+
+	if req.body != nil || r.body != nil {
+		t.Fatalf("expected nil body for both requests, got:%v %v", req.body, r.body)
+	}
+}