fix lint warnings (issue 2541) (#2551)

* Lint: fix some errcheck #2541

* Lint: fix passing structcheck #2541

* Lint: update fix structcheck #2541

* Lint: fix errcheck for basicauth, browse, fastcgi_test #2541

* Lint: fix errcheck for browse, fastcgi_test, fcgiclient, fcgiclient_test #2541

* Lint: fix errcheck for responsefilter_test, fcgilient_test #2541

* Lint: fix errcheck for header_test #2541

* Lint: update errcheck for fcgiclient_test #2541

* Lint: fix errcheck for server, header_test, fastcgi_test, https_test, recorder_test #2541

* Lint: fix errcheck for tplcontext, vhosttrie_test, internal_test, handler_test #2541

* Lint: fix errcheck for log_test, markdown mholt#2541

* Lint: fix errcheck for policy, body_test, proxy_test #2541

* Lint: fix errcheck for on multiple packages #2541

- reverseproxy
- reverseproxy_test
- upstream
- upstream_test
- body_test

* Lint: fix errcheck in multiple packages mholt#2541
- handler_test
- redirect_test
- requestid_test
- rewrite_test
- fileserver_test

* Lint: fix errcheck in multiple packages mholt#2541

- websocket
- setup
- collection
- redirect_test
- templates_test

* Lint: fix errcheck in logger test #2541

run goimports against #2551
- lexer_test
- log_test
- markdown

* Update caddyhttp/httpserver/logger_test.go

Co-Authored-By: Inconnu08 <taufiqrx8@gmail.com>

* Update log_test.go

* Lint: fix scope in logger_test #2541

* remove redundant err check in logger_test #2541

* fix alias in logger_test #2541

* fix import for format #2541

* refactor variable names and error check #2541

caddyhttp/httpserver/https_test.go

@@ -16,6 +16,7 @@ package httpserver
 
 import (
 	"fmt"
+	"log"
 	"net"
 	"net/http"
 	"net/http/httptest"
@@ -180,7 +181,9 @@ func TestEnableAutoHTTPS(t *testing.T) {
 		{}, // not managed - no changes!
 	}
 
-	enableAutoHTTPS(configs, false)
+	if err := enableAutoHTTPS(configs, false); err != nil {
+		log.Println("[ERROR]  enableAutoHTTPS failed: ", err)
+	}
 
 	if !configs[0].TLS.Enabled {
 		t.Errorf("Expected config 0 to have TLS.Enabled == true, but it was false")

caddyhttp/httpserver/logger_test.go

@@ -20,6 +20,7 @@ import (
 	"bytes"
 	"fmt"
 	"io/ioutil"
+	"log"
 	"os"
 	"path/filepath"
 	"strings"
@@ -179,9 +180,13 @@ func bootServer(location string, ch chan format.LogParts) (*syslog.Server, error
 
 	switch address.network {
 	case "tcp":
-		server.ListenTCP(address.address)
+		if err := server.ListenTCP(address.address); err != nil {
+			log.Println("[ERROR] server failed to listen on TCP address: ", err)
+		}
 	case "udp":
-		server.ListenUDP(address.address)
+		if err := server.ListenUDP(address.address); err != nil {
+			log.Println("[ERROR] server failed to listen on UDP address: ", err)
+		}
 	}
 
 	server.SetHandler(syslog.NewChannelHandler(ch))

caddyhttp/httpserver/recorder_test.go

@@ -44,7 +44,7 @@ func TestWrite(t *testing.T) {
 	responseTestString := "test"
 	recordRequest := NewResponseRecorder(w)
 	buf := []byte(responseTestString)
-	recordRequest.Write(buf)
+	_, _ = recordRequest.Write(buf)
 	if recordRequest.size != len(buf) {
 		t.Fatalf("Expected the bytes written counter to be %d, but instead found %d\n", len(buf), recordRequest.size)
 	}

caddyhttp/httpserver/server.go

@@ -234,7 +234,9 @@ func makeHTTPServerWithTimeouts(addr string, group []*SiteConfig) *http.Server {
 
 func (s *Server) wrapWithSvcHeaders(previousHandler http.Handler) http.HandlerFunc {
 	return func(w http.ResponseWriter, r *http.Request) {
-		s.quicServer.SetQuicHeaders(w.Header())
+		if err := s.quicServer.SetQuicHeaders(w.Header()); err != nil {
+			log.Println("[Error] failed to set proper headers for QUIC: ", err)
+		}
 		previousHandler.ServeHTTP(w, r)
 	}
 }
@@ -243,7 +245,7 @@ func (s *Server) wrapWithSvcHeaders(previousHandler http.Handler) http.HandlerFu
 // used to serve requests.
 func (s *Server) Listen() (net.Listener, error) {
 	if s.Server == nil {
-		return nil, fmt.Errorf("Server field is nil")
+		return nil, fmt.Errorf("server field is nil")
 	}
 
 	ln, err := net.Listen("tcp", s.Server.Addr)
@@ -324,7 +326,9 @@ func (s *Server) Serve(ln net.Listener) error {
 
 	defer func() {
 		if s.quicServer != nil {
-			s.quicServer.Close()
+			if err := s.quicServer.Close(); err != nil {
+				log.Println("[ERROR] failed to close QUIC server: ", err)
+			}
 		}
 	}()
 
@@ -555,8 +559,12 @@ func (ln tcpKeepAliveListener) Accept() (c net.Conn, err error) {
 	if err != nil {
 		return
 	}
-	tc.SetKeepAlive(true)
-	tc.SetKeepAlivePeriod(3 * time.Minute)
+	if err = tc.SetKeepAlive(true); err != nil {
+		return
+	}
+	if err = tc.SetKeepAlivePeriod(3 * time.Minute); err != nil {
+		return
+	}
 	return tc, nil
 }
 
@@ -594,7 +602,9 @@ func WriteTextResponse(w http.ResponseWriter, status int, body string) {
 	w.Header().Set("Content-Type", "text/plain; charset=utf-8")
 	w.Header().Set("X-Content-Type-Options", "nosniff")
 	w.WriteHeader(status)
-	w.Write([]byte(body))
+	if _, err := w.Write([]byte(body)); err != nil {
+		log.Println("[Error] failed to write body: ", err)
+	}
 }
 
 // SafePath joins siteRoot and reqPath and converts it to a path that can

caddyhttp/httpserver/tplcontext.go

@@ -19,6 +19,7 @@ import (
 	"crypto/rand"
 	"fmt"
 	"io/ioutil"
+	"log"
 	mathrand "math/rand"
 	"net"
 	"net/http"
@@ -420,7 +421,9 @@ func (c Context) RandomString(minLen, maxLen int) string {
 	// secureRandomBytes returns a number of bytes using crypto/rand.
 	secureRandomBytes := func(numBytes int) []byte {
 		randomBytes := make([]byte, numBytes)
-		rand.Read(randomBytes)
+		if _, err := rand.Read(randomBytes); err != nil {
+			log.Println("[ERROR] failed to read bytes: ", err)
+		}
 		return randomBytes
 	}
 

caddyhttp/httpserver/vhosttrie_test.go

@@ -15,6 +15,7 @@
 package httpserver
 
 import (
+	"log"
 	"net/http"
 	"net/http/httptest"
 	"testing"
@@ -103,7 +104,9 @@ func populateTestTrie(trie *vhostTrie, keys []string) {
 		func(key string) {
 			site := &SiteConfig{
 				middlewareChain: HandlerFunc(func(w http.ResponseWriter, r *http.Request) (int, error) {
-					w.Write([]byte(key))
+					if _, err := w.Write([]byte(key)); err != nil {
+						log.Println("[ERROR] failed to write bytes: ", err)
+					}
 					return 0, nil
 				}),
 			}
@@ -139,7 +142,9 @@ func assertTestTrie(t *testing.T, trie *vhostTrie, tests []vhostTrieTest, hasWil
 
 		// And it must be the correct value
 		resp := httptest.NewRecorder()
-		site.middlewareChain.ServeHTTP(resp, nil)
+		if _, err := site.middlewareChain.ServeHTTP(resp, nil); err != nil {
+			log.Println("[ERROR] failed to serve HTTP: ", err)
+		}
 		actualHandlerKey := resp.Body.String()
 		if actualHandlerKey != test.expectedKey {
 			t.Errorf("Test %d: Expected match '%s' but matched '%s'",