diff --git a/Readme.md b/Readme.md
index a006b28..45d45a7 100644
--- a/Readme.md
+++ b/Readme.md
@@ -11,8 +11,8 @@ and [IETF DNS-over-HTTPS (RFC 8484)](https://www.rfc-editor.org/rfc/rfc8484.txt)
 
 ## Installing
 ### From Source
-- Install [Go](https://golang.org), at least version 1.13. The newer the better.
-> Note for Debian/Ubuntu users: You need to set `$GOROOT` if you could not get your new version of Go selected by the Makefile.)
+- Install [Go](https://golang.org), at least version 1.13. The newer, the better.
+> Note for Debian/Ubuntu users: You need to set `$GOROOT` if you could not get your new version of Go selected by the Makefile.
 
 - First create an empty directory, used for `$GOPATH`:
 ```bash
@@ -88,7 +88,7 @@ The following is a typical DNS-over-HTTPS architecture:
     |  doh-client  +--+ Content Delivery Network +--+ (Apache, Nginx, Caddy) |
     +--------------+  +--------------------------+  +------------------------+
 
-Although DNS-over-HTTPS can work alone, a HTTP service muxer would be useful as
+Although DNS-over-HTTPS can work alone, an HTTP service muxer would be useful as
 you can host DNS-over-HTTPS along with other HTTPS services.
 
 HTTP/2 with at least TLS v1.3 is recommended. OCSP stapling must be enabled,
@@ -275,7 +275,7 @@ services:
 
 ### Example configuration: DNS-over-TLS
 
-There is no native [DNS-over-TLS](https://en.wikipedia.org/wiki/DNS_over_TLS) support but you can easily add it via nginx:
+There is no native [DNS-over-TLS](https://en.wikipedia.org/wiki/DNS_over_TLS) support, but you can easily add it via nginx:
 ```
 stream {
     server {
@@ -294,7 +294,7 @@ this approach does not need a stand-alone daemon to provide the DoT service.
 ## DNSSEC
 
 DNS-over-HTTPS is compatible with DNSSEC, and requests DNSSEC signatures by
-default. However signature validation is not built-in. It is highly recommended
+default. However, signature validation is not built-in. It is highly recommended
 that you install `unbound` or `bind` and pass results for them to validate DNS
 records. An instance of [Pi Hole](https://pi-hole.net) could also be used to validate DNS signatures as well as provide other capabilities.
 
diff --git a/doh-client/client.go b/doh-client/client.go
index df43561..e306d2e 100644
--- a/doh-client/client.go
+++ b/doh-client/client.go
@@ -38,39 +38,40 @@ import (
 	"sync"
 	"time"
 
-	"github.com/m13253/dns-over-https/v2/doh-client/config"
-	"github.com/m13253/dns-over-https/v2/doh-client/selector"
-	jsondns "github.com/m13253/dns-over-https/v2/json-dns"
 	"github.com/miekg/dns"
 	"golang.org/x/net/http2"
 	"golang.org/x/net/idna"
+
+	"github.com/m13253/dns-over-https/v2/doh-client/config"
+	"github.com/m13253/dns-over-https/v2/doh-client/selector"
+	jsondns "github.com/m13253/dns-over-https/v2/json-dns"
 )
 
 type Client struct {
-	conf                 *config.Config
-	bootstrap            []string
-	passthrough          []string
-	udpClient            *dns.Client
-	tcpClient            *dns.Client
-	udpServers           []*dns.Server
-	tcpServers           []*dns.Server
-	bootstrapResolver    *net.Resolver
+	httpClientLastCreate time.Time
 	cookieJar            http.CookieJar
+	selector             selector.Selector
 	httpClientMux        *sync.RWMutex
+	tcpClient            *dns.Client
+	bootstrapResolver    *net.Resolver
+	udpClient            *dns.Client
+	conf                 *config.Config
 	httpTransport        *http.Transport
 	httpClient           *http.Client
-	httpClientLastCreate time.Time
-	selector             selector.Selector
+	udpServers           []*dns.Server
+	tcpServers           []*dns.Server
+	passthrough          []string
+	bootstrap            []string
 }
 
 type DNSRequest struct {
+	err               error
 	response          *http.Response
 	reply             *dns.Msg
-	udpSize           uint16
-	ednsClientAddress net.IP
-	ednsClientNetmask uint8
 	currentUpstream   string
-	err               error
+	ednsClientAddress net.IP
+	udpSize           uint16
+	ednsClientNetmask uint8
 }
 
 func NewClient(conf *config.Config) (c *Client, err error) {
@@ -427,7 +428,7 @@ func (c *Client) handlerFunc(w dns.ResponseWriter, r *dns.Msg, isTCP bool) {
 
 	// https://developers.cloudflare.com/1.1.1.1/dns-over-https/request-structure/ says
 	// returns code will be 200 / 400 / 413 / 415 / 504, some server will return 503, so
-	// I think if status code is 5xx, upstream must has some problems
+	// I think if status code is 5xx, upstream must have some problems
 	/*if req.response.StatusCode/100 == 5 {
 		c.selector.ReportUpstreamStatus(upstream, selector.Medium)
 	}*/
diff --git a/doh-client/google.go b/doh-client/google.go
index f298ca3..90b75df 100644
--- a/doh-client/google.go
+++ b/doh-client/google.go
@@ -34,9 +34,10 @@ import (
 	"strconv"
 	"strings"
 
+	"github.com/miekg/dns"
+
 	"github.com/m13253/dns-over-https/v2/doh-client/selector"
 	jsondns "github.com/m13253/dns-over-https/v2/json-dns"
-	"github.com/miekg/dns"
 )
 
 func (c *Client) generateRequestGoogle(ctx context.Context, w dns.ResponseWriter, r *dns.Msg, isTCP bool, upstream *selector.Upstream) *DNSRequest {
@@ -77,7 +78,7 @@ func (c *Client) generateRequestGoogle(ctx context.Context, w dns.ResponseWriter
 		requestURL += fmt.Sprintf("&edns_client_subnet=%s/%d", ednsClientAddress.String(), ednsClientNetmask)
 	}
 
-	req, err := http.NewRequest(http.MethodGet, requestURL, nil)
+	req, err := http.NewRequest(http.MethodGet, requestURL, http.NoBody)
 	if err != nil {
 		log.Println(err)
 		reply := jsondns.PrepareReply(r)
diff --git a/doh-client/ietf.go b/doh-client/ietf.go
index bf9545c..69ccbe4 100644
--- a/doh-client/ietf.go
+++ b/doh-client/ietf.go
@@ -35,9 +35,10 @@ import (
 	"strings"
 	"time"
 
+	"github.com/miekg/dns"
+
 	"github.com/m13253/dns-over-https/v2/doh-client/selector"
 	jsondns "github.com/m13253/dns-over-https/v2/json-dns"
-	"github.com/miekg/dns"
 )
 
 func (c *Client) generateRequestIETF(ctx context.Context, w dns.ResponseWriter, r *dns.Msg, isTCP bool, upstream *selector.Upstream) *DNSRequest {
@@ -104,7 +105,7 @@ func (c *Client) generateRequestIETF(ctx context.Context, w dns.ResponseWriter,
 
 	var req *http.Request
 	if len(requestURL) < 2048 {
-		req, err = http.NewRequest(http.MethodGet, requestURL, nil)
+		req, err = http.NewRequest(http.MethodGet, requestURL, http.NoBody)
 		if err != nil {
 			log.Println(err)
 			reply := jsondns.PrepareReply(r)
diff --git a/doh-client/main.go b/doh-client/main.go
index ec8a569..0123c46 100644
--- a/doh-client/main.go
+++ b/doh-client/main.go
@@ -26,7 +26,6 @@ package main
 import (
 	"flag"
 	"fmt"
-	"io"
 	"log"
 	"os"
 	"runtime"
@@ -37,7 +36,7 @@ import (
 
 func checkPIDFile(pidFile string) (bool, error) {
 retry:
-	f, err := os.OpenFile(pidFile, os.O_WRONLY|os.O_CREATE|os.O_EXCL, 0666)
+	f, err := os.OpenFile(pidFile, os.O_WRONLY|os.O_CREATE|os.O_EXCL, 0o666)
 	if os.IsExist(err) {
 		pidStr, err := os.ReadFile(pidFile)
 		if err != nil {
@@ -63,7 +62,7 @@ retry:
 		return false, err
 	}
 	defer f.Close()
-	_, err = io.WriteString(f, strconv.FormatInt(int64(os.Getpid()), 10))
+	_, err = f.WriteString(strconv.FormatInt(int64(os.Getpid()), 10))
 	if err != nil {
 		return false, err
 	}
diff --git a/doh-client/selector/lvsWRRSelector.go b/doh-client/selector/lvsWRRSelector.go
index 0abe5a0..940bbd9 100644
--- a/doh-client/selector/lvsWRRSelector.go
+++ b/doh-client/selector/lvsWRRSelector.go
@@ -80,7 +80,7 @@ func (ls *LVSWRRSelector) StartEvaluate() {
 						acceptType = "application/dns-message"
 					}
 
-					req, err := http.NewRequest(http.MethodGet, upstreamURL, nil)
+					req, err := http.NewRequest(http.MethodGet, upstreamURL, http.NoBody)
 					if err != nil {
 						/*log.Println("upstream:", upstreamURL, "type:", typeMap[upstream.Type], "check failed:", err)
 						continue*/
diff --git a/doh-client/selector/nginxWRRSelector.go b/doh-client/selector/nginxWRRSelector.go
index a535a28..fafb5b6 100644
--- a/doh-client/selector/nginxWRRSelector.go
+++ b/doh-client/selector/nginxWRRSelector.go
@@ -73,7 +73,7 @@ func (ws *NginxWRRSelector) StartEvaluate() {
 						acceptType = "application/dns-message"
 					}
 
-					req, err := http.NewRequest(http.MethodGet, upstreamURL, nil)
+					req, err := http.NewRequest(http.MethodGet, upstreamURL, http.NoBody)
 					if err != nil {
 						/*log.Println("upstream:", upstreamURL, "type:", typeMap[upstream.Type], "check failed:", err)
 						continue*/
@@ -110,7 +110,7 @@ func (ws *NginxWRRSelector) StartEvaluate() {
 	}()
 }
 
-// nginx wrr like
+// nginx wrr like.
 func (ws *NginxWRRSelector) Get() *Upstream {
 	var (
 		total             int32
diff --git a/doh-client/selector/randomSelector.go b/doh-client/selector/randomSelector.go
index cd2880c..8a3ca7b 100644
--- a/doh-client/selector/randomSelector.go
+++ b/doh-client/selector/randomSelector.go
@@ -7,7 +7,7 @@ import (
 )
 
 func init() {
-	rand.Seed(time.Now().UnixNano())
+	rand.NewSource(time.Now().UnixNano())
 }
 
 type RandomSelector struct {
diff --git a/doh-server/config.go b/doh-server/config.go
index 8fb6c76..767069b 100644
--- a/doh-server/config.go
+++ b/doh-server/config.go
@@ -31,21 +31,21 @@ import (
 )
 
 type config struct {
-	Listen              []string `toml:"listen"`
+	TLSClientAuthCA     string   `toml:"tls_client_auth_ca"`
 	LocalAddr           string   `toml:"local_addr"`
 	Cert                string   `toml:"cert"`
 	Key                 string   `toml:"key"`
 	Path                string   `toml:"path"`
+	DebugHTTPHeaders    []string `toml:"debug_http_headers"`
+	Listen              []string `toml:"listen"`
 	Upstream            []string `toml:"upstream"`
 	Timeout             uint     `toml:"timeout"`
 	Tries               uint     `toml:"tries"`
 	Verbose             bool     `toml:"verbose"`
-	DebugHTTPHeaders    []string `toml:"debug_http_headers"`
 	LogGuessedIP        bool     `toml:"log_guessed_client_ip"`
 	ECSAllowNonGlobalIP bool     `toml:"ecs_allow_non_global_ip"`
 	ECSUsePreciseIP     bool     `toml:"ecs_use_precise_ip"`
 	TLSClientAuth       bool     `toml:"tls_client_auth"`
-	TLSClientAuthCA     string   `toml:"tls_client_auth_ca"`
 }
 
 func loadConfig(path string) (*config, error) {
diff --git a/doh-server/server.go b/doh-server/server.go
index 35b26c2..8efd584 100644
--- a/doh-server/server.go
+++ b/doh-server/server.go
@@ -53,11 +53,11 @@ type Server struct {
 type DNSRequest struct {
 	request         *dns.Msg
 	response        *dns.Msg
-	transactionID   uint16
 	currentUpstream string
-	isTailored      bool
-	errcode         int
 	errtext         string
+	errcode         int
+	transactionID   uint16
+	isTailored      bool
 }
 
 func NewServer(conf *config) (*Server, error) {
@@ -285,7 +285,7 @@ func (s *Server) handlerFunc(w http.ResponseWriter, r *http.Request) {
 
 func (s *Server) findClientIP(r *http.Request) net.IP {
 	noEcs := r.URL.Query().Get("no_ecs")
-	if strings.ToLower(noEcs) == "true" {
+	if strings.EqualFold(noEcs, "true") {
 		return nil
 	}