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

caddy_test.go

@@ -16,6 +16,7 @@ package caddy
 
 import (
 	"fmt"
+	"log"
 	"reflect"
 	"sync"
 	"testing"
@@ -103,13 +104,20 @@ func TestCaddyRestartCallbacks(t *testing.T) {
 			return nil
 		})
 
-		c.instance.Restart(CaddyfileInput{Contents: []byte(""), ServerTypeName: serverName})
+		_, err := c.instance.Restart(CaddyfileInput{Contents: []byte(""), ServerTypeName: serverName})
+		if err != nil {
+			log.Printf("[ERROR] Restart failed: %v", err)
+		}
 
 		if !reflect.DeepEqual(calls, test.expectedCalls) {
 			t.Errorf("Test %d: Callbacks expected: %v, got: %v", i, test.expectedCalls, calls)
 		}
 
-		c.instance.Stop()
+		err = c.instance.Stop()
+		if err != nil {
+			log.Printf("[ERROR] Stop failed: %v", err)
+		}
+
 		c.instance.Wait()
 	}
 

caddyfile/lexer_test.go

@@ -15,6 +15,7 @@
 package caddyfile
 
 import (
+	"log"
 	"strings"
 	"testing"
 )
@@ -158,7 +159,9 @@ func TestLexer(t *testing.T) {
 
 func tokenize(input string) (tokens []Token) {
 	l := lexer{}
-	l.load(strings.NewReader(input))
+	if err := l.load(strings.NewReader(input)); err != nil {
+		log.Printf("[ERROR] load failed: %v", err)
+	}
 	for l.next() {
 		tokens = append(tokens, l.token)
 	}

caddyhttp/basicauth/basicauth.go

@@ -26,6 +26,7 @@ import (
 	"crypto/subtle"
 	"fmt"
 	"io"
+	"log"
 	"net/http"
 	"os"
 	"path/filepath"
@@ -193,11 +194,15 @@ func PlainMatcher(passw string) PasswordMatcher {
 	// compare hashes of equal length instead of actual password
 	// to avoid leaking password length
 	passwHash := sha1.New()
-	passwHash.Write([]byte(passw))
+	if _, err := passwHash.Write([]byte(passw)); err != nil {
+		log.Printf("[ERROR] unable to write password hash: %v", err)
+	}
 	passwSum := passwHash.Sum(nil)
 	return func(pw string) bool {
 		pwHash := sha1.New()
-		pwHash.Write([]byte(pw))
+		if _, err := pwHash.Write([]byte(pw)); err != nil {
+			log.Printf("[ERROR] unable to write password hash: %v", err)
+		}
 		pwSum := pwHash.Sum(nil)
 		return subtle.ConstantTimeCompare([]byte(pwSum), []byte(passwSum)) == 1
 	}

caddyhttp/browse/browse.go

@@ -59,34 +59,34 @@ type Config struct {
 
 // A Listing is the context used to fill out a template.
 type Listing struct {
-	// The name of the directory (the last element of the path)
+	// The name of the directory (the last element of the path).
 	Name string
 
-	// The full path of the request
+	// The full path of the request.
 	Path string
 
-	// Whether the parent directory is browsable
+	// Whether the parent directory is browse-able.
 	CanGoUp bool
 
-	// The items (files and folders) in the path
+	// The items (files and folders) in the path.
 	Items []FileInfo
 
-	// The number of directories in the listing
+	// The number of directories in the listing.
 	NumDirs int
 
-	// The number of files (items that aren't directories) in the listing
+	// The number of files (items that aren't directories) in the listing.
 	NumFiles int
 
-	// Which sorting order is used
+	// Which sorting order is used.
 	Sort string
 
-	// And which order
+	// And which order.
 	Order string
 
-	// If ≠0 then Items have been limited to that many elements
+	// If ≠0 then Items have been limited to that many elements.
 	ItemsLimitedTo int
 
-	// Optional custom variables for use in browse templates
+	// Optional custom variables for use in browse templates.
 	User interface{}
 
 	httpserver.Context
@@ -244,7 +244,7 @@ func (l Listing) applySort() {
 
 func directoryListing(files []os.FileInfo, canGoUp bool, urlPath string, config *Config) (Listing, bool) {
 	var (
-		fileinfos           []FileInfo
+		fileInfos           []FileInfo
 		dirCount, fileCount int
 		hasIndexFile        bool
 	)
@@ -272,14 +272,14 @@ func directoryListing(files []os.FileInfo, canGoUp bool, urlPath string, config
 			continue
 		}
 
-		url := url.URL{Path: "./" + name} // prepend with "./" to fix paths with ':' in the name
+		u := url.URL{Path: "./" + name} // prepend with "./" to fix paths with ':' in the name
 
-		fileinfos = append(fileinfos, FileInfo{
+		fileInfos = append(fileInfos, FileInfo{
 			IsDir:     isDir,
 			IsSymlink: isSymlink(f),
 			Name:      f.Name(),
 			Size:      f.Size(),
-			URL:       url.String(),
+			URL:       u.String(),
 			ModTime:   f.ModTime().UTC(),
 			Mode:      f.Mode(),
 		})
@@ -289,7 +289,7 @@ func directoryListing(files []os.FileInfo, canGoUp bool, urlPath string, config
 		Name:     path.Base(urlPath),
 		Path:     urlPath,
 		CanGoUp:  canGoUp,
-		Items:    fileinfos,
+		Items:    fileInfos,
 		NumDirs:  dirCount,
 		NumFiles: fileCount,
 	}, hasIndexFile
@@ -504,7 +504,7 @@ func (b Browse) ServeListing(w http.ResponseWriter, r *http.Request, requestedFi
 
 	}
 
-	buf.WriteTo(w)
+	_, _ = buf.WriteTo(w)
 
 	return http.StatusOK, nil
 }

caddyhttp/fastcgi/fastcgi_test.go

@@ -16,6 +16,7 @@ package fastcgi
 
 import (
 	"context"
+	"log"
 	"net"
 	"net/http"
 	"net/http/fcgi"
@@ -39,11 +40,20 @@ func TestServeHTTP(t *testing.T) {
 	if err != nil {
 		t.Fatalf("Unable to create listener for test: %v", err)
 	}
-	defer listener.Close()
-	go fcgi.Serve(listener, http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		w.Header().Set("Content-Length", bodyLenStr)
-		w.Write([]byte(body))
-	}))
+	defer func() { _ = listener.Close() }()
+
+	go func() {
+		err := fcgi.Serve(listener, http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			w.Header().Set("Content-Length", bodyLenStr)
+			_, err := w.Write([]byte(body))
+			if err != nil {
+				log.Printf("[ERROR] unable to write header: %v", err)
+			}
+		}))
+		if err != nil {
+			log.Printf("[ERROR] unable to start server: %v", err)
+		}
+	}()
 
 	handler := Handler{
 		Next:  nil,
@@ -147,7 +157,7 @@ func TestBuildEnv(t *testing.T) {
 		SplitPath:  ".php",
 		IndexFiles: []string{"index.php"},
 	}
-	url, err := url.Parse("http://localhost:2015/fgci_test.php?test=foobar")
+	u, err := url.Parse("http://localhost:2015/fgci_test.php?test=foobar")
 	if err != nil {
 		t.Error("Unexpected error:", err.Error())
 	}
@@ -155,7 +165,7 @@ func TestBuildEnv(t *testing.T) {
 	var newReq = func() *http.Request {
 		r := http.Request{
 			Method:     "GET",
-			URL:        url,
+			URL:        u,
 			Proto:      "HTTP/1.1",
 			ProtoMajor: 1,
 			ProtoMinor: 1,
@@ -274,7 +284,7 @@ func TestReadTimeout(t *testing.T) {
 		if err != nil {
 			t.Fatalf("Test %d: Unable to create listener for test: %v", i, err)
 		}
-		defer listener.Close()
+		defer func() { _ = listener.Close() }()
 
 		handler := Handler{
 			Next: nil,
@@ -293,11 +303,16 @@ func TestReadTimeout(t *testing.T) {
 		w := httptest.NewRecorder()
 
 		wg.Add(1)
-		go fcgi.Serve(listener, http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-			time.Sleep(test.sleep)
-			w.WriteHeader(http.StatusOK)
-			wg.Done()
-		}))
+		go func() {
+			err := fcgi.Serve(listener, http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+				time.Sleep(test.sleep)
+				w.WriteHeader(http.StatusOK)
+				wg.Done()
+			}))
+			if err != nil {
+				log.Printf("[ERROR] unable to start server: %v", err)
+			}
+		}()
 
 		got, err := handler.ServeHTTP(w, r)
 		if test.shouldErr {
@@ -334,7 +349,7 @@ func TestSendTimeout(t *testing.T) {
 		if err != nil {
 			t.Fatalf("Test %d: Unable to create listener for test: %v", i, err)
 		}
-		defer listener.Close()
+		defer func() { _ = listener.Close() }()
 
 		handler := Handler{
 			Next: nil,
@@ -352,9 +367,14 @@ func TestSendTimeout(t *testing.T) {
 		}
 		w := httptest.NewRecorder()
 
-		go fcgi.Serve(listener, http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-			w.WriteHeader(http.StatusOK)
-		}))
+		go func() {
+			err := fcgi.Serve(listener, http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+				w.WriteHeader(http.StatusOK)
+			}))
+			if err != nil {
+				log.Printf("[ERROR] unable to start server: %v", err)
+			}
+		}()
 
 		got, err := handler.ServeHTTP(w, r)
 		if test.shouldErr {

caddyhttp/fastcgi/fcgiclient.go

@@ -175,15 +175,13 @@ func (rec *record) read(r io.Reader) (buf []byte, err error) {
 // FCGIClient implements a FastCGI client, which is a standard for
 // interfacing external applications with Web servers.
 type FCGIClient struct {
-	mutex       sync.Mutex
-	rwc         io.ReadWriteCloser
-	h           header
-	buf         bytes.Buffer
-	stderr      bytes.Buffer
-	keepAlive   bool
-	reqID       uint16
-	readTimeout time.Duration
-	sendTimeout time.Duration
+	mutex     sync.Mutex
+	rwc       io.ReadWriteCloser
+	h         header
+	buf       bytes.Buffer
+	stderr    bytes.Buffer
+	keepAlive bool
+	reqID     uint16
 }
 
 // DialWithDialerContext connects to the fcgi responder at the specified network address, using custom net.Dialer
@@ -397,7 +395,7 @@ func (c *FCGIClient) Do(p map[string]string, req io.Reader) (r io.Reader, err er
 
 	body := newWriter(c, Stdin)
 	if req != nil {
-		io.Copy(body, req)
+		_, _ = io.Copy(body, req)
 	}
 	body.Close()
 

caddyhttp/fastcgi/fcgiclient_test.go

@@ -59,7 +59,9 @@ type FastCGIServer struct{}
 
 func (s FastCGIServer) ServeHTTP(resp http.ResponseWriter, req *http.Request) {
 
-	req.ParseMultipartForm(100000000)
+	if err := req.ParseMultipartForm(100000000); err != nil {
+		log.Printf("[ERROR] failed to parse: %v", err)
+	}
 
 	stat := "PASSED"
 	fmt.Fprintln(resp, "-")
@@ -68,15 +70,15 @@ func (s FastCGIServer) ServeHTTP(resp http.ResponseWriter, req *http.Request) {
 		length := 0
 		for k0, v0 := range req.Form {
 			h := md5.New()
-			io.WriteString(h, v0[0])
-			md5 := fmt.Sprintf("%x", h.Sum(nil))
+			_, _ = io.WriteString(h, v0[0])
+			_md5 := fmt.Sprintf("%x", h.Sum(nil))
 
 			length += len(k0)
 			length += len(v0[0])
 
-			// echo error when key != md5(val)
-			if md5 != k0 {
-				fmt.Fprintln(resp, "server:err ", md5, k0)
+			// echo error when key != _md5(val)
+			if _md5 != k0 {
+				fmt.Fprintln(resp, "server:err ", _md5, k0)
 				stat = "FAILED"
 			}
 		}
@@ -197,8 +199,12 @@ func generateRandFile(size int) (p string, m string) {
 	for i := 0; i < size/16; i++ {
 		buf := make([]byte, 16)
 		binary.PutVarint(buf, rand.Int63())
-		fo.Write(buf)
-		h.Write(buf)
+		if _, err := fo.Write(buf); err != nil {
+			log.Printf("[ERROR] failed to write buffer: %v\n", err)
+		}
+		if _, err := h.Write(buf); err != nil {
+			log.Printf("[ERROR] failed to write buffer: %v\n", err)
+		}
 	}
 	m = fmt.Sprintf("%x", h.Sum(nil))
 	return
@@ -214,12 +220,13 @@ func DisabledTest(t *testing.T) {
 	go func() {
 		listener, err := net.Listen("tcp", ipPort)
 		if err != nil {
-			// handle error
 			log.Println("listener creation failed: ", err)
 		}
 
 		srv := new(FastCGIServer)
-		fcgi.Serve(listener, srv)
+		if err := fcgi.Serve(listener, srv); err != nil {
+			log.Print("[ERROR] failed to start server: ", err)
+		}
 	}()
 
 	time.Sleep(1 * time.Second)
@@ -244,7 +251,7 @@ func DisabledTest(t *testing.T) {
 	for i := 0x00; i < 0xff; i++ {
 		v0 := strings.Repeat(string(i), 256)
 		h := md5.New()
-		io.WriteString(h, v0)
+		_, _ = io.WriteString(h, v0)
 		k0 := fmt.Sprintf("%x", h.Sum(nil))
 		data += k0 + "=" + url.QueryEscape(v0) + "&"
 	}
@@ -261,7 +268,7 @@ func DisabledTest(t *testing.T) {
 	for i := 0x00; i < 0xff; i++ {
 		v0 := strings.Repeat(string(i), 4096)
 		h := md5.New()
-		io.WriteString(h, v0)
+		_, _ = io.WriteString(h, v0)
 		k0 := fmt.Sprintf("%x", h.Sum(nil))
 		p1[k0] = v0
 	}
@@ -285,6 +292,10 @@ func DisabledTest(t *testing.T) {
 	delete(f0, "m0")
 	sendFcgi(1, fcgiParams, nil, nil, f0)
 
-	os.Remove(path0)
-	os.Remove(path1)
+	if err := os.Remove(path0); err != nil {
+		log.Println("[ERROR] failed to remove path: ", err)
+	}
+	if err := os.Remove(path1); err != nil {
+		log.Println("[ERROR] failed to remove path: ", err)
+	}
 }

caddyhttp/gzip/responsefilter_test.go

@@ -17,6 +17,7 @@ package gzip
 import (
 	"compress/gzip"
 	"fmt"
+	"log"
 	"net/http"
 	"net/http/httptest"
 	"testing"
@@ -77,7 +78,9 @@ func TestResponseFilterWriter(t *testing.T) {
 	for i, ts := range tests {
 		server.Next = httpserver.HandlerFunc(func(w http.ResponseWriter, r *http.Request) (int, error) {
 			w.Header().Set("Content-Length", fmt.Sprint(len(ts.body)))
-			w.Write([]byte(ts.body))
+			if _, err := w.Write([]byte(ts.body)); err != nil {
+				log.Println("[ERROR] failed to write response: ", err)
+			}
 			return 200, nil
 		})
 
@@ -86,7 +89,9 @@ func TestResponseFilterWriter(t *testing.T) {
 
 		w := httptest.NewRecorder()
 
-		server.ServeHTTP(w, r)
+		if _, err := server.ServeHTTP(w, r); err != nil {
+			log.Println("[ERROR] unable to serve a gzipped response: ", err)
+		}
 
 		resp := w.Body.String()
 
@@ -109,7 +114,9 @@ func TestResponseGzippedOutput(t *testing.T) {
 
 	server.Next = httpserver.HandlerFunc(func(w http.ResponseWriter, r *http.Request) (int, error) {
 		w.Header().Set("Content-Encoding", "gzip")
-		w.Write([]byte("gzipped"))
+		if _, err := w.Write([]byte("gzipped")); err != nil {
+			log.Println("[ERROR] failed to write response: ", err)
+		}
 		return 200, nil
 	})
 
@@ -117,7 +124,9 @@ func TestResponseGzippedOutput(t *testing.T) {
 	r.Header.Set("Accept-Encoding", "gzip")
 
 	w := httptest.NewRecorder()
-	server.ServeHTTP(w, r)
+	if _, err := server.ServeHTTP(w, r); err != nil {
+		log.Println("[ERROR] unable to serve a gzipped response: ", err)
+	}
 	resp := w.Body.String()
 
 	if resp != "gzipped" {

caddyhttp/header/header_test.go

@@ -16,6 +16,7 @@ package header
 
 import (
 	"fmt"
+	"log"
 	"net/http"
 	"net/http/httptest"
 	"os"
@@ -69,7 +70,9 @@ func TestHeader(t *testing.T) {
 		// preset header
 		rec.Header().Set("Server", "Caddy")
 
-		he.ServeHTTP(rec, req)
+		if _, err := he.ServeHTTP(rec, req); err != nil {
+			log.Println("[ERROR] ServeHTTP failed: ", err)
+		}
 
 		if got := rec.Header().Get(test.name); got != test.value {
 			t.Errorf("Test %d: Expected %s header to be %q but was %q",
@@ -81,7 +84,9 @@ func TestHeader(t *testing.T) {
 func TestMultipleHeaders(t *testing.T) {
 	he := Headers{
 		Next: httpserver.HandlerFunc(func(w http.ResponseWriter, r *http.Request) (int, error) {
-			fmt.Fprint(w, "This is a test")
+			if _, err := fmt.Fprint(w, "This is a test"); err != nil {
+				log.Println("[ERROR] Fprint failed: ", err)
+			}
 			return 0, nil
 		}),
 		Rules: []Rule{
@@ -97,7 +102,9 @@ func TestMultipleHeaders(t *testing.T) {
 	}
 
 	rec := httptest.NewRecorder()
-	he.ServeHTTP(rec, req)
+	if _, err := he.ServeHTTP(rec, req); err != nil {
+		log.Println("[ERROR] ServeHTTP failed: ", err)
+	}
 
 	desiredHeaders := []string{"</css/main.css>; rel=preload", "</images/image.png>; rel=preload"}
 	actualHeaders := rec.HeaderMap[http.CanonicalHeaderKey("Link")]

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'",

caddyhttp/internalsrv/internal_test.go

@@ -16,6 +16,7 @@ package internalsrv
 
 import (
 	"fmt"
+	"log"
 	"net/http"
 	"net/http/httptest"
 	"testing"
@@ -126,7 +127,9 @@ func internalTestHandlerFunc(w http.ResponseWriter, r *http.Request) (int, error
 		w.WriteHeader(http.StatusOK)
 		w.Header().Set("Content-Type", contentTypeOctetStream)
 		w.Header().Set("Content-Length", strconv.Itoa(len(internalProtectedData)))
-		w.Write([]byte(internalProtectedData))
+		if _, err := w.Write([]byte(internalProtectedData)); err != nil {
+			log.Println("[ERROR] failed to write bytes: ", err)
+		}
 		return 0, nil
 	}
 

caddyhttp/limits/handler_test.go

@@ -16,6 +16,7 @@ package limits
 
 import (
 	"io/ioutil"
+	"log"
 	"net/http"
 	"net/http/httptest"
 	"strings"
@@ -39,7 +40,9 @@ func TestBodySizeLimit(t *testing.T) {
 	}
 
 	r := httptest.NewRequest("GET", "/", strings.NewReader(expectContent+expectContent))
-	l.ServeHTTP(httptest.NewRecorder(), r)
+	if _, err := l.ServeHTTP(httptest.NewRecorder(), r); err != nil {
+		log.Println("[ERROR] failed to serve HTTP: ", err)
+	}
 	if got := string(gotContent); got != expectContent {
 		t.Errorf("expected content[%s], got[%s]", expectContent, got)
 	}

caddyhttp/log/log_test.go

@@ -17,6 +17,7 @@ package log
 import (
 	"bytes"
 	"io/ioutil"
+	"log"
 	"net/http"
 	"net/http/httptest"
 	"strings"
@@ -89,7 +90,9 @@ func TestLogRequestBody(t *testing.T) {
 		}},
 		Next: httpserver.HandlerFunc(func(w http.ResponseWriter, r *http.Request) (int, error) {
 			// drain up body
-			ioutil.ReadAll(r.Body)
+			if _, err := ioutil.ReadAll(r.Body); err != nil {
+				log.Println("[ERROR] failed to read request body: ", err)
+			}
 			return 0, nil
 		}),
 	}
@@ -153,7 +156,9 @@ func TestMultiEntries(t *testing.T) {
 		}},
 		Next: httpserver.HandlerFunc(func(w http.ResponseWriter, r *http.Request) (int, error) {
 			// drain up body
-			ioutil.ReadAll(r.Body)
+			if _, err := ioutil.ReadAll(r.Body); err != nil {
+				log.Println("[ERROR] failed to read request body: ", err)
+			}
 			return 0, nil
 		}),
 	}

caddyhttp/markdown/markdown.go

@@ -17,6 +17,7 @@
 package markdown
 
 import (
+	"log"
 	"net/http"
 	"os"
 	"path"
@@ -168,7 +169,9 @@ func (md Markdown) ServeHTTP(w http.ResponseWriter, r *http.Request) (int, error
 	w.Header().Set("Content-Length", strconv.Itoa(len(html)))
 	httpserver.SetLastModifiedHeader(w, lastModTime)
 	if r.Method == http.MethodGet {
-		w.Write(html)
+		if _, err := w.Write(html); err != nil {
+			log.Println("[ERROR] failed to write html response: ", err)
+		}
 	}
 	return http.StatusOK, nil
 }

caddyhttp/proxy/body_test.go

@@ -18,6 +18,7 @@ import (
 	"bytes"
 	"io"
 	"io/ioutil"
+	"log"
 	"net/http"
 	"net/http/httptest"
 	"testing"
@@ -25,13 +26,15 @@ import (
 
 func TestBodyRetry(t *testing.T) {
 	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		io.Copy(w, r.Body)
-		r.Body.Close()
+		if _, err := io.Copy(w, r.Body); err != nil {
+			log.Println("[ERROR] failed to copy response body: ", err)
+		}
+		_ = r.Body.Close()
 	}))
 	defer ts.Close()
 
-	testcase := "test content"
-	req, err := http.NewRequest(http.MethodPost, ts.URL, bytes.NewBufferString(testcase))
+	testCase := "test content"
+	req, err := http.NewRequest(http.MethodPost, ts.URL, bytes.NewBufferString(testCase))
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -47,12 +50,16 @@ func TestBodyRetry(t *testing.T) {
 	// simulate fail request
 	host := req.URL.Host
 	req.URL.Host = "example.com"
-	body.rewind()
+	if err := body.rewind(); err != nil {
+		log.Println("[ERROR] failed re-read bufferedBody: ", err)
+	}
 	_, _ = http.DefaultTransport.RoundTrip(req)
 
 	// retry request
 	req.URL.Host = host
-	body.rewind()
+	if err := body.rewind(); err != nil {
+		log.Println("[ERROR] failed re-read bufferedBody: ", err)
+	}
 	resp, err := http.DefaultTransport.RoundTrip(req)
 	if err != nil {
 		t.Fatal(err)
@@ -61,13 +68,15 @@ func TestBodyRetry(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	resp.Body.Close()
-	if string(result) != testcase {
-		t.Fatalf("result = %s, want %s", result, testcase)
+	_ = resp.Body.Close()
+	if string(result) != testCase {
+		t.Fatalf("result = %s, want %s", result, testCase)
 	}
 
 	// try one more time for body reuse
-	body.rewind()
+	if err := body.rewind(); err != nil {
+		log.Println("[ERROR] failed re-read bufferedBody: ", err)
+	}
 	resp, err = http.DefaultTransport.RoundTrip(req)
 	if err != nil {
 		t.Fatal(err)
@@ -76,8 +85,8 @@ func TestBodyRetry(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	resp.Body.Close()
-	if string(result) != testcase {
-		t.Fatalf("result = %s, want %s", result, testcase)
+	_ = resp.Body.Close()
+	if string(result) != testCase {
+		t.Fatalf("result = %s, want %s", result, testCase)
 	}
 }

caddyhttp/proxy/policy.go

@@ -16,6 +16,7 @@ package proxy
 
 import (
 	"hash/fnv"
+	"log"
 	"math"
 	"math/rand"
 	"net"
@@ -139,7 +140,9 @@ func hostByHashing(pool HostPool, s string) *UpstreamHost {
 // hash calculates a hash based on string s
 func hash(s string) uint32 {
 	h := fnv.New32a()
-	h.Write([]byte(s))
+	if _, err := h.Write([]byte(s)); err != nil {
+		log.Println("[ERROR] failed to write bytes: ", err)
+	}
 	return h.Sum32()
 }
 

caddyhttp/proxy/proxy_test.go

@@ -97,7 +97,9 @@ func TestReverseProxy(t *testing.T) {
 	requestReceived := false
 	backend := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		// read the body (even if it's empty) to make Go parse trailers
-		io.Copy(ioutil.Discard, r.Body)
+		if _, err := io.Copy(ioutil.Discard, r.Body); err != nil {
+			log.Println("[ERROR] failed to copy bytes: ", err)
+		}
 
 		verifyHeadersTrailers(r.Header, r.Trailer)
 		requestReceived = true
@@ -113,7 +115,9 @@ func TestReverseProxy(t *testing.T) {
 		}
 
 		w.WriteHeader(http.StatusOK)
-		w.Write([]byte("Hello, client"))
+		if _, err := w.Write([]byte("Hello, client")); err != nil {
+			log.Println("[ERROR] failed to write response: ", err)
+		}
 
 		// Set trailers.
 		shallowCopyTrailers(w.Header(), testTrailers, true)
@@ -149,7 +153,9 @@ func TestReverseProxy(t *testing.T) {
 	}
 
 	w := httptest.NewRecorder()
-	p.ServeHTTP(w, r)
+	if _, err := p.ServeHTTP(w, r); err != nil {
+		log.Println("[ERROR] failed to serve HTTP: ", err)
+	}
 	res := w.Result()
 
 	if !requestReceived {
@@ -165,7 +171,9 @@ func TestReverseProxy(t *testing.T) {
 	})
 	rr.Replacer = httpserver.NewReplacer(r, rr, "-")
 
-	p.ServeHTTP(rr, r)
+	if _, err := p.ServeHTTP(rr, r); err != nil {
+		log.Println("[ERROR] failed to serve HTTP: ", err)
+	}
 
 	if got, want := rr.Replacer.Replace("{upstream}"), backend.URL; got != want {
 		t.Errorf("Expected custom placeholder {upstream} to be set (%s), but it wasn't; got: %s", want, got)
@@ -196,7 +204,9 @@ func TestReverseProxyInsecureSkipVerify(t *testing.T) {
 	backend := newTLSServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		requestReceived = true
 		requestWasHTTP2 = r.ProtoAtLeast(2, 0)
-		w.Write([]byte("Hello, client"))
+		if _, err := w.Write([]byte("Hello, client")); err != nil {
+			log.Println("[ERROR] failed to write response: ", err)
+		}
 	}))
 	defer backend.Close()
 
@@ -210,7 +220,9 @@ func TestReverseProxyInsecureSkipVerify(t *testing.T) {
 	r := httptest.NewRequest("GET", "/", nil)
 	w := httptest.NewRecorder()
 
-	p.ServeHTTP(w, r)
+	if _, err := p.ServeHTTP(w, r); err != nil {
+		log.Println("[ERROR] failed to serve HTTP: ", err)
+	}
 
 	if !requestReceived {
 		t.Error("Even with insecure HTTPS, expected backend to receive request, but it didn't")
@@ -306,7 +318,9 @@ func TestReverseProxyTimeout(t *testing.T) {
 	w := httptest.NewRecorder()
 
 	start := time.Now()
-	p.ServeHTTP(w, r)
+	if _, err := p.ServeHTTP(w, r); err != nil {
+		log.Println("[ERROR] failed to serve HTTP: ", err)
+	}
 	took := time.Since(start)
 
 	if took > timeout+errorMargin {
@@ -342,7 +356,9 @@ func TestWebSocketReverseProxyNonHijackerPanic(t *testing.T) {
 	}
 
 	nonHijacker := httptest.NewRecorder()
-	p.ServeHTTP(nonHijacker, r)
+	if _, err := p.ServeHTTP(nonHijacker, r); err != nil {
+		log.Println("[ERROR] failed to serve HTTP: ", err)
+	}
 }
 
 func TestWebSocketReverseProxyBackendShutDown(t *testing.T) {
@@ -360,7 +376,9 @@ func TestWebSocketReverseProxyBackendShutDown(t *testing.T) {
 	// Get proxy to use for the test
 	p := newWebSocketTestProxy(backend.URL, false, 30*time.Second)
 	backendProxy := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		p.ServeHTTP(w, r)
+		if _, err := p.ServeHTTP(w, r); err != nil {
+			log.Println("[ERROR] failed to serve HTTP: ", err)
+		}
 	}))
 	defer backendProxy.Close()
 
@@ -404,7 +422,9 @@ func TestWebSocketReverseProxyServeHTTPHandler(t *testing.T) {
 	w := &recorderHijacker{httptest.NewRecorder(), new(fakeConn)}
 
 	// Booya! Do the test.
-	p.ServeHTTP(w, r)
+	if _, err := p.ServeHTTP(w, r); err != nil {
+		log.Println("[ERROR] failed to serve HTTP: ", err)
+	}
 
 	// Make sure the backend accepted the WS connection.
 	// Mostly interested in the Upgrade and Connection response headers
@@ -429,7 +449,9 @@ func TestWebSocketReverseProxyFromWSClient(t *testing.T) {
 	// Echo server allows us to test that socket bytes are properly
 	// being proxied.
 	wsEcho := httptest.NewServer(websocket.Handler(func(ws *websocket.Conn) {
-		io.Copy(ws, ws)
+		if _, err := io.Copy(ws, ws); err != nil {
+			log.Println("[ERROR] failed to copy: ", err)
+		}
 	}))
 	defer wsEcho.Close()
 
@@ -441,13 +463,15 @@ func TestWebSocketReverseProxyFromWSClient(t *testing.T) {
 	// WS client will connect to this test server, not
 	// the echo client directly.
 	echoProxy := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		p.ServeHTTP(w, r)
+		if _, err := p.ServeHTTP(w, r); err != nil {
+			log.Println("[ERROR] failed to serve HTTP: ", err)
+		}
 	}))
 	defer echoProxy.Close()
 
 	// Set up WebSocket client
-	url := strings.Replace(echoProxy.URL, "http://", "ws://", 1)
-	ws, err := websocket.Dial(url, "", echoProxy.URL)
+	u := strings.Replace(echoProxy.URL, "http://", "ws://", 1)
+	ws, err := websocket.Dial(u, "", echoProxy.URL)
 
 	if err != nil {
 		t.Fatal(err)
@@ -475,20 +499,24 @@ func TestWebSocketReverseProxyFromWSClient(t *testing.T) {
 
 func TestWebSocketReverseProxyFromWSSClient(t *testing.T) {
 	wsEcho := newTLSServer(websocket.Handler(func(ws *websocket.Conn) {
-		io.Copy(ws, ws)
+		if _, err := io.Copy(ws, ws); err != nil {
+			log.Println("[ERROR] failed to copy: ", err)
+		}
 	}))
 	defer wsEcho.Close()
 
 	p := newWebSocketTestProxy(wsEcho.URL, true, 30*time.Second)
 
 	echoProxy := newTLSServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		p.ServeHTTP(w, r)
+		if _, err := p.ServeHTTP(w, r); err != nil {
+			log.Println("[ERROR] failed to serve HTTP: ", err)
+		}
 	}))
 	defer echoProxy.Close()
 
 	// Set up WebSocket client
-	url := strings.Replace(echoProxy.URL, "https://", "wss://", 1)
-	wsCfg, err := websocket.NewConfig(url, echoProxy.URL)
+	u := strings.Replace(echoProxy.URL, "https://", "wss://", 1)
+	wsCfg, err := websocket.NewConfig(u, echoProxy.URL)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -558,7 +586,9 @@ func TestUnixSocketProxy(t *testing.T) {
 	p := newWebSocketTestProxy(url, false, 30*time.Second)
 
 	echoProxy := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		p.ServeHTTP(w, r)
+		if _, err := p.ServeHTTP(w, r); err != nil {
+			log.Println("[ERROR] failed to serve HTTP: ", err)
+		}
 	}))
 	defer echoProxy.Close()
 
@@ -599,14 +629,14 @@ func GetSocketProxy(messageFormat string, prefix string) (*Proxy, *httptest.Serv
 
 	dir, err := ioutil.TempDir("", "caddy_proxytest")
 	if err != nil {
-		return nil, nil, dir, fmt.Errorf("Failed to make temp dir to contain unix socket. %v", err)
+		return nil, nil, dir, fmt.Errorf("failed to make temp dir to contain unix socket. %v", err)
 	}
 	socketPath := filepath.Join(dir, "test_socket")
 
 	ln, err := net.Listen("unix", socketPath)
 	if err != nil {
 		os.RemoveAll(dir)
-		return nil, nil, dir, fmt.Errorf("Unable to listen: %v", err)
+		return nil, nil, dir, fmt.Errorf("unable to listen: %v", err)
 	}
 	ts.Listener = ln
 
@@ -619,7 +649,9 @@ func GetSocketProxy(messageFormat string, prefix string) (*Proxy, *httptest.Serv
 
 func GetTestServerMessage(p *Proxy, ts *httptest.Server, path string) (string, error) {
 	echoProxy := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		p.ServeHTTP(w, r)
+		if _, err := p.ServeHTTP(w, r); err != nil {
+			log.Println("[ERROR] failed to serve HTTP: ", err)
+		}
 	}))
 
 	// *httptest.Server is passed so it can be `defer`red properly
@@ -628,13 +660,13 @@ func GetTestServerMessage(p *Proxy, ts *httptest.Server, path string) (string, e
 
 	res, err := http.Get(echoProxy.URL + path)
 	if err != nil {
-		return "", fmt.Errorf("Unable to GET: %v", err)
+		return "", fmt.Errorf("unable to GET: %v", err)
 	}
 
 	greeting, err := ioutil.ReadAll(res.Body)
 	res.Body.Close()
 	if err != nil {
-		return "", fmt.Errorf("Unable to read body: %v", err)
+		return "", fmt.Errorf("unable to read body: %v", err)
 	}
 
 	return fmt.Sprintf("%s", greeting), nil
@@ -707,7 +739,9 @@ func TestUpstreamHeadersUpdate(t *testing.T) {
 	var actualHeaders http.Header
 	var actualHost string
 	backend := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		w.Write([]byte("Hello, client"))
+		if _, err := w.Write([]byte("Hello, client")); err != nil {
+			log.Println("[ERROR] failed to write response: ", err)
+		}
 		actualHeaders = r.Header
 		actualHost = r.Host
 	}))
@@ -752,7 +786,9 @@ func TestUpstreamHeadersUpdate(t *testing.T) {
 	r.Header.Add("Regex-Me", "I was originally this")
 	r.Header.Add("Regexreplace-Me", "The host is bad")
 
-	p.ServeHTTP(w, r)
+	if _, err := p.ServeHTTP(w, r); err != nil {
+		log.Println("[ERROR] failed to serve HTTP: ", err)
+	}
 
 	replacer := httpserver.NewReplacer(r, nil, "")
 
@@ -790,7 +826,9 @@ func TestDownstreamHeadersUpdate(t *testing.T) {
 		w.Header().Add("Overwrite-Me", "Overwrite-Value")
 		w.Header().Add("Regex-Me", "I was originally this")
 		w.Header().Add("Regexreplace-Me", "The host is bad")
-		w.Write([]byte("Hello, client"))
+		if _, err := w.Write([]byte("Hello, client")); err != nil {
+			log.Println("[ERROR] failed to write response: ", err)
+		}
 	}))
 	defer backend.Close()
 
@@ -822,7 +860,9 @@ func TestDownstreamHeadersUpdate(t *testing.T) {
 	// set a predefined overwritten header
 	w.Header().Set("Overwrite-Me", "Initial")
 
-	p.ServeHTTP(w, r)
+	if _, err := p.ServeHTTP(w, r); err != nil {
+		log.Println("[ERROR] failed to serve HTTP: ", err)
+	}
 
 	replacer := httpserver.NewReplacer(r, nil, "")
 	actualHeaders := w.Header()
@@ -880,7 +920,9 @@ func TestMultiReverseProxyFromClient(t *testing.T) {
 
 	// This is a full end-end test, so the proxy handler.
 	proxy := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		p.ServeHTTP(w, r)
+		if _, err := p.ServeHTTP(w, r); err != nil {
+			log.Println("[ERROR] failed to serve HTTP: ", err)
+		}
 	}))
 	defer proxy.Close()
 
@@ -936,7 +978,9 @@ func TestHostSimpleProxyNoHeaderForward(t *testing.T) {
 	var requestHost string
 	backend := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		requestHost = r.Host
-		w.Write([]byte("Hello, client"))
+		if _, err := w.Write([]byte("Hello, client")); err != nil {
+			log.Println("[ERROR] failed to write response: ", err)
+		}
 	}))
 	defer backend.Close()
 
@@ -951,7 +995,9 @@ func TestHostSimpleProxyNoHeaderForward(t *testing.T) {
 
 	w := httptest.NewRecorder()
 
-	p.ServeHTTP(w, r)
+	if _, err := p.ServeHTTP(w, r); err != nil {
+		log.Println("[ERROR] failed to serve HTTP: ", err)
+	}
 
 	if !strings.Contains(backend.URL, "//") {
 		t.Fatalf("The URL of the backend server doesn't contains //: %s", backend.URL)
@@ -1015,7 +1061,9 @@ func testReverseProxyTransparentHeaders(t *testing.T, remoteAddr, forwardedForHe
 	w := httptest.NewRecorder()
 
 	// Act
-	p.ServeHTTP(w, r)
+	if _, err := p.ServeHTTP(w, r); err != nil {
+		log.Println("[ERROR] failed to serve HTTP: ", err)
+	}
 
 	// Assert
 	if got := actualHeaders["X-Forwarded-For"]; !reflect.DeepEqual(got, expected) {
@@ -1028,7 +1076,9 @@ func TestHostHeaderReplacedUsingForward(t *testing.T) {
 	var requestHost string
 	backend := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		requestHost = r.Host
-		w.Write([]byte("Hello, client"))
+		if _, err := w.Write([]byte("Hello, client")); err != nil {
+			log.Println("[ERROR] failed to write response: ", err)
+		}
 	}))
 	defer backend.Close()
 
@@ -1046,7 +1096,9 @@ func TestHostHeaderReplacedUsingForward(t *testing.T) {
 
 	w := httptest.NewRecorder()
 
-	p.ServeHTTP(w, r)
+	if _, err := p.ServeHTTP(w, r); err != nil {
+		log.Println("[ERROR] failed to serve HTTP: ", err)
+	}
 
 	if proxyHostHeader != requestHost {
 		t.Fatalf("Expected %s as a Host header got %s\n", proxyHostHeader, requestHost)
@@ -1077,11 +1129,17 @@ func basicAuthTestcase(t *testing.T, upstreamUser, clientUser *url.Userinfo) {
 		u, p, ok := r.BasicAuth()
 
 		if ok {
-			w.Write([]byte(u))
+			if _, err := w.Write([]byte(u)); err != nil {
+				log.Println("[ERROR] failed to write bytes: ", err)
+			}
 		}
 		if ok && p != "" {
-			w.Write([]byte(":"))
-			w.Write([]byte(p))
+			if _, err := w.Write([]byte(":")); err != nil {
+				log.Println("[ERROR] failed to write bytes: ", err)
+			}
+			if _, err := w.Write([]byte(p)); err != nil {
+				log.Println("[ERROR] failed to write bytes: ", err)
+			}
 		}
 	}))
 	defer backend.Close()
@@ -1107,7 +1165,9 @@ func basicAuthTestcase(t *testing.T, upstreamUser, clientUser *url.Userinfo) {
 	}
 	w := httptest.NewRecorder()
 
-	p.ServeHTTP(w, r)
+	if _, err := p.ServeHTTP(w, r); err != nil {
+		log.Println("[ERROR] failed to serve HTTP: ", err)
+	}
 
 	if w.Code != 200 {
 		t.Fatalf("Invalid response code: %d", w.Code)
@@ -1243,7 +1303,9 @@ func TestReverseProxyRetry(t *testing.T) {
 
 	// set up proxy
 	backend := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		io.Copy(w, r.Body)
+		if _, err := io.Copy(w, r.Body); err != nil {
+			log.Println("[ERROR] failed to copy: ", err)
+		}
 		r.Body.Close()
 	}))
 	defer backend.Close()
@@ -1275,8 +1337,8 @@ func TestReverseProxyRetry(t *testing.T) {
 	}))
 	defer middle.Close()
 
-	testcase := "test content"
-	r, err := http.NewRequest("POST", middle.URL, bytes.NewBufferString(testcase))
+	testCase := "test content"
+	r, err := http.NewRequest("POST", middle.URL, bytes.NewBufferString(testCase))
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -1289,8 +1351,8 @@ func TestReverseProxyRetry(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	if string(b) != testcase {
-		t.Fatalf("string(b) = %s, want %s", string(b), testcase)
+	if string(b) != testCase {
+		t.Fatalf("string(b) = %s, want %s", string(b), testCase)
 	}
 }
 
@@ -1300,7 +1362,10 @@ func TestReverseProxyLargeBody(t *testing.T) {
 
 	// set up proxy
 	backend := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		io.Copy(ioutil.Discard, r.Body)
+		if _, err := io.Copy(ioutil.Discard, r.Body); err != nil {
+			log.Println("[ERROR] failed to copy: ", err)
+		}
+
 		r.Body.Close()
 	}))
 	defer backend.Close()
@@ -1329,8 +1394,8 @@ func TestReverseProxyLargeBody(t *testing.T) {
 
 	// We want to see how much memory the proxy module requires for this request.
 	// So lets record the mem stats before we start it.
-	begMemstats := &runtime.MemStats{}
-	runtime.ReadMemStats(begMemstats)
+	begMemStats := &runtime.MemStats{}
+	runtime.ReadMemStats(begMemStats)
 
 	r, err := http.NewRequest("POST", middle.URL, &noopReader{len: bodySize})
 	if err != nil {
@@ -1347,7 +1412,7 @@ func TestReverseProxyLargeBody(t *testing.T) {
 	runtime.ReadMemStats(endMemstats)
 
 	// ...to calculate the total amount of allocated memory during the request.
-	totalAlloc := endMemstats.TotalAlloc - begMemstats.TotalAlloc
+	totalAlloc := endMemstats.TotalAlloc - begMemStats.TotalAlloc
 
 	// If that's as much as the size of the body itself it's a serious sign that the
 	// request was not "streamed" to the upstream without buffering it first.
@@ -1369,7 +1434,9 @@ func TestCancelRequest(t *testing.T) {
 		}
 
 		w.WriteHeader(http.StatusOK)
-		w.Write([]byte("Hello, client"))
+		if _, err := w.Write([]byte("Hello, client")); err != nil {
+			log.Println("[ERROR] failed to write response: ", err)
+		}
 	}))
 	defer backend.Close()
 
@@ -1502,11 +1569,10 @@ func newPrefixedWebSocketTestProxy(backendAddr string, prefix string) *Proxy {
 }
 
 type fakeWsUpstream struct {
-	name          string
-	without       string
-	insecure      bool
-	timeout       time.Duration
-	fallbackDelay time.Duration
+	name     string
+	without  string
+	insecure bool
+	timeout  time.Duration
 }
 
 func (u *fakeWsUpstream) From() string {
@@ -1574,7 +1640,9 @@ var _ httpserver.HTTPInterfaces = testResponseRecorder{}
 
 func BenchmarkProxy(b *testing.B) {
 	backend := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		w.Write([]byte("Hello, client"))
+		if _, err := w.Write([]byte("Hello, client")); err != nil {
+			log.Println("[ERROR] failed to write response: ", err)
+		}
 	}))
 	defer backend.Close()
 
@@ -1602,7 +1670,9 @@ func BenchmarkProxy(b *testing.B) {
 			b.Fatalf("Failed to create request: %v", err)
 		}
 		b.StartTimer()
-		p.ServeHTTP(w, r)
+		if _, err := p.ServeHTTP(w, r); err != nil {
+			log.Println("[ERROR] failed to serve HTTP: ", err)
+		}
 	}
 }
 
@@ -1684,7 +1754,9 @@ func TestQuic(t *testing.T) {
 			return
 		}
 		handler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-			w.Write([]byte(content))
+			if _, err := w.Write([]byte(content)); err != nil {
+				log.Println("[ERROR] failed to write bytes: ", err)
+			}
 			w.WriteHeader(200)
 		})
 		err = h2quic.ListenAndServeQUIC(

caddyhttp/proxy/reverseproxy.go

@@ -31,6 +31,7 @@ import (
 	"crypto/x509"
 	"fmt"
 	"io"
+	"log"
 	"net"
 	"net/http"
 	"net/url"
@@ -69,7 +70,9 @@ func pooledIoCopy(dst io.Writer, src io.Reader) {
 	// Due to that we extend buf's length to its capacity here and
 	// ensure it's always non-zero.
 	bufCap := cap(buf)
-	io.CopyBuffer(dst, src, buf[0:bufCap:bufCap])
+	if _, err := io.CopyBuffer(dst, src, buf[0:bufCap:bufCap]); err != nil {
+		log.Println("[ERROR] failed to copy buffer: ", err)
+	}
 }
 
 // onExitFlushLoop is a callback set by tests to detect the state of the
@@ -132,12 +135,12 @@ func (rp *ReverseProxy) srvDialerFunc(locator string, timeout time.Duration) fun
 }
 
 func singleJoiningSlash(a, b string) string {
-	aslash := strings.HasSuffix(a, "/")
-	bslash := strings.HasPrefix(b, "/")
+	aSlash := strings.HasSuffix(a, "/")
+	bSlash := strings.HasPrefix(b, "/")
 	switch {
-	case aslash && bslash:
+	case aSlash && bSlash:
 		return a + b[1:]
-	case !aslash && !bslash && b != "":
+	case !aSlash && !bSlash && b != "":
 		return a + "/" + b
 	}
 	return a + b
@@ -275,7 +278,9 @@ func NewSingleHostReverseProxy(target *url.URL, without string, keepalive int, t
 			transport.MaxIdleConnsPerHost = keepalive
 		}
 		if httpserver.HTTP2 {
-			http2.ConfigureTransport(transport)
+			if err := http2.ConfigureTransport(transport); err != nil {
+				log.Println("[ERROR] failed to configure transport to use HTTP/2: ", err)
+			}
 		}
 		rp.Transport = transport
 	} else {
@@ -284,7 +289,9 @@ func NewSingleHostReverseProxy(target *url.URL, without string, keepalive int, t
 			Dial:  rp.dialer.Dial,
 		}
 		if httpserver.HTTP2 {
-			http2.ConfigureTransport(transport)
+			if err := http2.ConfigureTransport(transport); err != nil {
+				log.Println("[ERROR] failed to configure transport to use HTTP/2: ", err)
+			}
 		}
 		rp.Transport = transport
 	}
@@ -394,7 +401,9 @@ func (rp *ReverseProxy) ServeHTTP(rw http.ResponseWriter, outreq *http.Request,
 			if err != nil {
 				return err
 			}
-			outreq.Write(backendConn)
+			if err := outreq.Write(backendConn); err != nil {
+				log.Println("[ERROR] failed to write: ", err)
+			}
 		}
 		defer backendConn.Close()
 
@@ -416,7 +425,9 @@ func (rp *ReverseProxy) ServeHTTP(rw http.ResponseWriter, outreq *http.Request,
 				if err != nil {
 					return err
 				}
-				backendConn.Write(rbuf)
+				if _, err := backendConn.Write(rbuf); err != nil {
+					log.Println("[ERROR] failed to write data to connection: ", err)
+				}
 			}
 		}
 		go func() {
@@ -434,7 +445,7 @@ func (rp *ReverseProxy) ServeHTTP(rw http.ResponseWriter, outreq *http.Request,
 		bodyOpen := true
 		closeBody := func() {
 			if bodyOpen {
-				res.Body.Close()
+				_ = res.Body.Close()
 				bodyOpen = false
 			}
 		}
@@ -681,7 +692,7 @@ func getTransportDialTLS(t *http.Transport) func(network, addr string) (net.Conn
 			errc <- err
 		}()
 		if err := <-errc; err != nil {
-			plainConn.Close()
+			_ = plainConn.Close()
 			return nil, err
 		}
 		if !tlsClientConfig.InsecureSkipVerify {
@@ -690,7 +701,7 @@ func getTransportDialTLS(t *http.Transport) func(network, addr string) (net.Conn
 				hostname = stripPort(addr)
 			}
 			if err := tlsConn.VerifyHostname(hostname); err != nil {
-				plainConn.Close()
+				_ = plainConn.Close()
 				return nil, err
 			}
 		}

caddyhttp/proxy/reverseproxy_test.go

@@ -15,6 +15,7 @@
 package proxy
 
 import (
+	"log"
 	"net"
 	"net/http"
 	"net/http/httptest"
@@ -39,10 +40,14 @@ func setupTLSServer() {
 		func(w http.ResponseWriter, r *http.Request) {
 			if r.URL.Path == "/test-path" {
 				w.WriteHeader(expectedStatus)
-				w.Write([]byte(expectedResponse))
+				if _, err := w.Write([]byte(expectedResponse)); err != nil {
+					log.Println("[ERROR] failed to write bytes: ", err)
+				}
 			} else {
 				w.WriteHeader(404)
-				w.Write([]byte("Not found"))
+				if _, err := w.Write([]byte("Not found")); err != nil {
+					log.Println("[ERROR] failed to write bytes: ", err)
+				}
 			}
 		}))
 }
@@ -52,10 +57,14 @@ func setupTest() {
 		func(w http.ResponseWriter, r *http.Request) {
 			if r.URL.Path == "/test-path" {
 				w.WriteHeader(expectedStatus)
-				w.Write([]byte(expectedResponse))
+				if _, err := w.Write([]byte(expectedResponse)); err != nil {
+					log.Println("[ERROR] failed to write bytes: ", err)
+				}
 			} else {
 				w.WriteHeader(404)
-				w.Write([]byte("Not found"))
+				if _, err := w.Write([]byte("Not found")); err != nil {
+					log.Println("[ERROR] failed to write bytes: ", err)
+				}
 			}
 		}))
 }

caddyhttp/proxy/upstream.go

@@ -21,6 +21,7 @@ import (
 	"fmt"
 	"io"
 	"io/ioutil"
+	"log"
 	"net"
 	"net/http"
 	"net/textproto"
@@ -632,8 +633,10 @@ func (u *staticUpstream) healthCheck() {
 					return true
 				}
 				defer func() {
-					io.Copy(ioutil.Discard, r.Body)
-					r.Body.Close()
+					if _, err := io.Copy(ioutil.Discard, r.Body); err != nil {
+						log.Println("[ERROR] failed to copy: ", err)
+					}
+					_ = r.Body.Close()
 				}()
 				if r.StatusCode < 200 || r.StatusCode >= 400 {
 					return true

caddyhttp/proxy/upstream_test.go

@@ -18,6 +18,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"log"
 	"net"
 	"net/http"
 	"net/http/httptest"
@@ -249,7 +250,9 @@ func TestParseBlockHealthCheck(t *testing.T) {
 		u := staticUpstream{}
 		c := caddyfile.NewDispenser("Testfile", strings.NewReader(test.config))
 		for c.Next() {
-			parseBlock(&c, &u, false)
+			if err := parseBlock(&c, &u, false); err != nil {
+				log.Println("[ERROR] failed to parse block: ", err)
+			}
 		}
 		if u.HealthCheck.Interval.String() != test.interval {
 			t.Errorf(
@@ -300,7 +303,7 @@ func TestStop(t *testing.T) {
 			// Set up proxy.
 			var counter int64
 			backend := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-				r.Body.Close()
+				_ = r.Body.Close()
 				atomic.AddInt64(&counter, 1)
 			}))
 
@@ -522,7 +525,7 @@ func TestHealthCheckPort(t *testing.T) {
 	var counter int64
 
 	healthCounter := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		r.Body.Close()
+		_ = r.Body.Close()
 		atomic.AddInt64(&counter, 1)
 	}))
 
@@ -592,8 +595,8 @@ func TestHealthCheckPort(t *testing.T) {
 
 func TestHealthCheckContentString(t *testing.T) {
 	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		fmt.Fprintf(w, "blablabla good blablabla")
-		r.Body.Close()
+		_, _ = fmt.Fprintf(w, "blablabla good blablabla")
+		_ = r.Body.Close()
 	}))
 	_, port, err := net.SplitHostPort(server.Listener.Addr().String())
 	if err != nil {
@@ -638,7 +641,9 @@ func TestHealthCheckContentString(t *testing.T) {
 				}
 				t.Errorf("Health check bad response")
 			}
-			upstream.Stop()
+			if err := upstream.Stop(); err != nil {
+				log.Println("[ERROR] failed to stop upstream: ", err)
+			}
 		}
 	}
 }

caddyhttp/push/handler_test.go

@@ -17,6 +17,7 @@ package push
 import (
 	"errors"
 	"io/ioutil"
+	"log"
 	"net/http"
 	"net/http/httptest"
 	"os"
@@ -67,7 +68,9 @@ func TestMiddlewareWillPushResources(t *testing.T) {
 	pushingWriter := &MockedPusher{ResponseWriter: writer}
 
 	// when
-	middleware.ServeHTTP(pushingWriter, request)
+	if _, err := middleware.ServeHTTP(pushingWriter, request); err != nil {
+		log.Println("[ERROR] failed to serve HTTP: ", err)
+	}
 
 	// then
 	expectedPushedResources := map[string]*http.PushOptions{
@@ -111,7 +114,9 @@ func TestMiddlewareWillPushResourcesWithMergedHeaders(t *testing.T) {
 	pushingWriter := &MockedPusher{ResponseWriter: writer}
 
 	// when
-	middleware.ServeHTTP(pushingWriter, request)
+	if _, err := middleware.ServeHTTP(pushingWriter, request); err != nil {
+		log.Println("[ERROR] failed to serve HTTP: ", err)
+	}
 
 	// then
 	expectedPushedResources := map[string]*http.PushOptions{
@@ -156,7 +161,9 @@ func TestMiddlewareShouldntDoRecursivePush(t *testing.T) {
 	pushingWriter := &MockedPusher{ResponseWriter: writer}
 
 	// when
-	middleware.ServeHTTP(pushingWriter, request)
+	if _, err := middleware.ServeHTTP(pushingWriter, request); err != nil {
+		log.Println("[ERROR] failed to serve HTTP: ", err)
+	}
 
 	// then
 	if len(pushingWriter.pushed) > 0 {
@@ -190,7 +197,9 @@ func TestMiddlewareShouldStopPushingOnError(t *testing.T) {
 	pushingWriter := &MockedPusher{ResponseWriter: writer, returnedError: errors.New("Cannot push right now")}
 
 	// when
-	middleware.ServeHTTP(pushingWriter, request)
+	if _, err := middleware.ServeHTTP(pushingWriter, request); err != nil {
+		log.Println("[ERROR] failed to serve HTTP: ", err)
+	}
 
 	// then
 	expectedPushedResources := map[string]*http.PushOptions{
@@ -406,7 +415,7 @@ func TestMiddlewareShouldPushIndexFile(t *testing.T) {
 
 	pushingWriter := &MockedPusher{
 		ResponseWriter: httptest.NewRecorder(),
-		returnedError:  errors.New("Cannot push right now"),
+		returnedError:  errors.New("cannot push right now"),
 	}
 
 	// when
@@ -461,7 +470,7 @@ func TestMiddlewareShouldNotPushIndexFileWhenNotARule(t *testing.T) {
 
 	pushingWriter := &MockedPusher{
 		ResponseWriter: httptest.NewRecorder(),
-		returnedError:  errors.New("Cannot push right now"),
+		returnedError:  errors.New("cannot push right now"),
 	}
 
 	// when

caddyhttp/redirect/redirect_test.go

@@ -19,6 +19,7 @@ import (
 	"context"
 	"crypto/tls"
 	"io/ioutil"
+	"log"
 	"net/http"
 	"net/http/httptest"
 	"strings"
@@ -84,7 +85,9 @@ func TestRedirect(t *testing.T) {
 		}
 
 		rec := httptest.NewRecorder()
-		re.ServeHTTP(rec, req)
+		if _, err := re.ServeHTTP(rec, req); err != nil {
+			log.Println("[ERROR] failed to serve HTTP: ", err)
+		}
 
 		if rec.Header().Get("Location") != test.expectedLocation {
 			t.Errorf("Test %d: Expected Location header to be %q but was %q",
@@ -117,7 +120,9 @@ func TestParametersRedirect(t *testing.T) {
 	req = req.WithContext(ctx)
 
 	rec := httptest.NewRecorder()
-	re.ServeHTTP(rec, req)
+	if _, err := re.ServeHTTP(rec, req); err != nil {
+		log.Println("[ERROR] failed to serve HTTP: ", err)
+	}
 
 	if got, want := rec.Header().Get("Location"), "http://example.com/a?b=c"; got != want {
 		t.Fatalf("Test 1: expected location header %s but was %s", want, got)
@@ -136,7 +141,9 @@ func TestParametersRedirect(t *testing.T) {
 	ctx = context.WithValue(req.Context(), httpserver.OriginalURLCtxKey, *req.URL)
 	req = req.WithContext(ctx)
 
-	re.ServeHTTP(rec, req)
+	if _, err := re.ServeHTTP(rec, req); err != nil {
+		log.Println("[ERROR] failed to serve HTTP: ", err)
+	}
 
 	if got, want := rec.Header().Get("Location"), "http://example.com/a/d?b=c&e=f"; got != want {
 		t.Fatalf("Test 2: expected location header %s but was %s", want, got)
@@ -158,7 +165,9 @@ func TestMetaRedirect(t *testing.T) {
 		}
 
 		rec := httptest.NewRecorder()
-		re.ServeHTTP(rec, req)
+		if _, err := re.ServeHTTP(rec, req); err != nil {
+			log.Println("[ERROR] failed to serve HTTP: ", err)
+		}
 
 		body, err := ioutil.ReadAll(rec.Body)
 		if err != nil {

caddyhttp/requestid/requestid_test.go

@@ -15,6 +15,7 @@
 package requestid
 
 import (
+	"log"
 	"net/http"
 	"net/http/httptest"
 	"testing"
@@ -39,7 +40,9 @@ func TestRequestIDHandler(t *testing.T) {
 	}
 	rec := httptest.NewRecorder()
 
-	handler.ServeHTTP(rec, req)
+	if _, err := handler.ServeHTTP(rec, req); err != nil {
+		log.Println("[ERROR] failed to serve HTTP: ", err)
+	}
 }
 
 func TestRequestIDFromHeader(t *testing.T) {
@@ -63,5 +66,7 @@ func TestRequestIDFromHeader(t *testing.T) {
 	req.Header.Set(headerName, headerValue)
 	rec := httptest.NewRecorder()
 
-	handler.ServeHTTP(rec, req)
+	if _, err := handler.ServeHTTP(rec, req); err != nil {
+		log.Println("[ERROR] failed to serve HTTP: ", err)
+	}
 }

caddyhttp/rewrite/rewrite_test.go

@@ -17,6 +17,7 @@ package rewrite
 import (
 	"context"
 	"fmt"
+	"log"
 	"net/http"
 	"net/http/httptest"
 	"strings"
@@ -123,7 +124,9 @@ func TestRewrite(t *testing.T) {
 		req = req.WithContext(ctx)
 
 		rec := httptest.NewRecorder()
-		rw.ServeHTTP(rec, req)
+		if _, err := rw.ServeHTTP(rec, req); err != nil {
+			log.Println("[ERROR] failed to serve HTTP: ", err)
+		}
 
 		if got, want := rec.Body.String(), test.expectedTo; got != want {
 			t.Errorf("Test %d: Expected URL to be '%s' but was '%s'", i, want, got)
@@ -162,7 +165,9 @@ func TestWordpress(t *testing.T) {
 		req = req.WithContext(ctx)
 
 		rec := httptest.NewRecorder()
-		rw.ServeHTTP(rec, req)
+		if _, err := rw.ServeHTTP(rec, req); err != nil {
+			log.Println("[ERROR] failed to serve HTTP: ", err)
+		}
 
 		if got, want := rec.Body.String(), test.expectedTo; got != want {
 			t.Errorf("Test %d: Expected URL to be '%s' but was '%s'", i, want, got)
@@ -171,6 +176,6 @@ func TestWordpress(t *testing.T) {
 }
 
 func urlPrinter(w http.ResponseWriter, r *http.Request) (int, error) {
-	fmt.Fprint(w, r.URL.String())
+	_, _ = fmt.Fprint(w, r.URL.String())
 	return 0, nil
 }

caddyhttp/staticfiles/fileserver_test.go

@@ -18,6 +18,7 @@ import (
 	"context"
 	"errors"
 	"io/ioutil"
+	"log"
 	"net/http"
 	"net/http/httptest"
 	"os"
@@ -35,7 +36,7 @@ func TestServeHTTP(t *testing.T) {
 	tmpWebRootDir := beforeServeHTTPTest(t)
 	defer afterServeHTTPTest(t, tmpWebRootDir)
 
-	fileserver := FileServer{
+	fileServer := FileServer{
 		Root:       http.Dir(filepath.Join(tmpWebRootDir, webrootName)),
 		Hide:       []string{"dir/hidden.html"},
 		IndexPages: DefaultIndexPages,
@@ -288,7 +289,7 @@ func TestServeHTTP(t *testing.T) {
 		}
 
 		// perform the test
-		status, err := fileserver.ServeHTTP(responseRecorder, request)
+		status, err := fileServer.ServeHTTP(responseRecorder, request)
 		etag := responseRecorder.Header().Get("Etag")
 		body := responseRecorder.Body.String()
 		vary := responseRecorder.Header().Get("Vary")
@@ -357,7 +358,9 @@ func beforeServeHTTPTest(t *testing.T) string {
 		parentDir := filepath.Dir(absFile)
 		_, err = os.Stat(parentDir)
 		if err != nil {
-			os.MkdirAll(parentDir, os.ModePerm)
+			if err := os.MkdirAll(parentDir, os.ModePerm); err != nil {
+				log.Println("[ERROR] MkdirAll failed: ", err)
+			}
 		}
 
 		// now create the test files
@@ -371,7 +374,7 @@ func beforeServeHTTPTest(t *testing.T) string {
 		if err != nil {
 			t.Fatalf("Failed to write to %s. Error was: %v", absFile, err)
 		}
-		f.Close()
+		_ = f.Close()
 
 		// and set the last modified time
 		err = os.Chtimes(absFile, fixedTime, fixedTime)
@@ -511,7 +514,7 @@ func TestServeHTTPFailingStat(t *testing.T) {
 
 	for i, test := range tests {
 		// initialize a file server. The FileSystem will not fail, but calls to the Stat method of the returned File object will
-		fileserver := FileServer{Root: failingFS{err: nil, fileImpl: failingFile{err: test.statErr}}}
+		fileServer := FileServer{Root: failingFS{err: nil, fileImpl: failingFile{err: test.statErr}}}
 
 		// prepare the request and response
 		request, err := http.NewRequest("GET", "https://foo/", nil)
@@ -520,7 +523,7 @@ func TestServeHTTPFailingStat(t *testing.T) {
 		}
 		responseRecorder := httptest.NewRecorder()
 
-		status, actualErr := fileserver.ServeHTTP(responseRecorder, request)
+		status, actualErr := fileServer.ServeHTTP(responseRecorder, request)
 
 		// check the status
 		if status != test.expectedStatus {

caddyhttp/templates/templates_test.go

@@ -17,6 +17,7 @@ package templates
 import (
 	"bytes"
 	"context"
+	"log"
 	"net/http"
 	"net/http/httptest"
 	"sync"
@@ -127,7 +128,9 @@ func TestTemplates(t *testing.T) {
 
 			rec := httptest.NewRecorder()
 
-			c.tpl.ServeHTTP(rec, req)
+			if _, err := c.tpl.ServeHTTP(rec, req); err != nil {
+				log.Println("[ERROR] failed to serve HTTP: ", err)
+			}
 
 			if rec.Code != c.respCode {
 				t.Fatalf("Test: Wrong response code: %d, should be %d", rec.Code, c.respCode)

caddyhttp/websocket/websocket.go

@@ -21,6 +21,7 @@ import (
 	"bufio"
 	"bytes"
 	"io"
+	"log"
 	"net"
 	"net/http"
 	"os"
@@ -80,9 +81,9 @@ type (
 
 // ServeHTTP converts the HTTP request to a WebSocket connection and serves it up.
 func (ws WebSocket) ServeHTTP(w http.ResponseWriter, r *http.Request) (int, error) {
-	for _, sockconfig := range ws.Sockets {
-		if httpserver.Path(r.URL.Path).Matches(sockconfig.Path) {
-			return serveWS(w, r, &sockconfig)
+	for _, sockConfig := range ws.Sockets {
+		if httpserver.Path(r.URL.Path).Matches(sockConfig.Path) {
+			return serveWS(w, r, &sockConfig)
 		}
 	}
 
@@ -135,7 +136,7 @@ func serveWS(w http.ResponseWriter, r *http.Request, config *Config) (int, error
 	go pumpStdout(conn, stdout, done)
 	pumpStdin(conn, stdin)
 
-	stdin.Close() // close stdin to end the process
+	_ = stdin.Close() // close stdin to end the process
 
 	if err := cmd.Process.Signal(os.Interrupt); err != nil { // signal an interrupt to kill the process
 		return http.StatusInternalServerError, err
@@ -155,7 +156,9 @@ func serveWS(w http.ResponseWriter, r *http.Request, config *Config) (int, error
 	// status for an "exited" process is greater
 	// than 0, but isn't really an error per se.
 	// just going to ignore it for now.
-	cmd.Wait()
+	if err := cmd.Wait(); err != nil {
+		log.Println("[ERROR] failed to release resources: ", err)
+	}
 
 	return 0, nil
 }
@@ -221,8 +224,15 @@ func pumpStdin(conn *websocket.Conn, stdin io.WriteCloser) {
 	// Setup our connection's websocket ping/pong handlers from our const values.
 	defer conn.Close()
 	conn.SetReadLimit(maxMessageSize)
-	conn.SetReadDeadline(time.Now().Add(pongWait))
-	conn.SetPongHandler(func(string) error { conn.SetReadDeadline(time.Now().Add(pongWait)); return nil })
+	if err := conn.SetReadDeadline(time.Now().Add(pongWait)); err != nil {
+		log.Println("[ERROR] failed to set read deadline: ", err)
+	}
+	conn.SetPongHandler(func(string) error {
+		if err := conn.SetReadDeadline(time.Now().Add(pongWait)); err != nil {
+			log.Println("[ERROR] failed to set read deadline: ", err)
+		}
+		return nil
+	})
 	for {
 		_, message, err := conn.ReadMessage()
 		if err != nil {
@@ -240,19 +250,24 @@ func pumpStdin(conn *websocket.Conn, stdin io.WriteCloser) {
 func pumpStdout(conn *websocket.Conn, stdout io.Reader, done chan struct{}) {
 	go pinger(conn, done)
 	defer func() {
-		conn.Close()
+		_ = conn.Close()
 		close(done) // make sure to close the pinger when we are done.
 	}()
 
 	s := bufio.NewScanner(stdout)
 	for s.Scan() {
-		conn.SetWriteDeadline(time.Now().Add(writeWait))
+		if err := conn.SetWriteDeadline(time.Now().Add(writeWait)); err != nil {
+			log.Println("[ERROR] failed to set write deadline: ", err)
+		}
 		if err := conn.WriteMessage(websocket.TextMessage, bytes.TrimSpace(s.Bytes())); err != nil {
 			break
 		}
 	}
 	if s.Err() != nil {
-		conn.WriteControl(websocket.CloseMessage, websocket.FormatCloseMessage(websocket.CloseGoingAway, s.Err().Error()), time.Time{})
+		err := conn.WriteControl(websocket.CloseMessage, websocket.FormatCloseMessage(websocket.CloseGoingAway, s.Err().Error()), time.Time{})
+		if err != nil {
+			log.Println("[ERROR] WriteControl failed: ", err)
+		}
 	}
 }
 
@@ -265,7 +280,10 @@ func pinger(conn *websocket.Conn, done chan struct{}) {
 		select {
 		case <-ticker.C:
 			if err := conn.WriteControl(websocket.PingMessage, []byte{}, time.Now().Add(writeWait)); err != nil {
-				conn.WriteControl(websocket.CloseMessage, websocket.FormatCloseMessage(websocket.CloseGoingAway, err.Error()), time.Time{})
+				err := conn.WriteControl(websocket.CloseMessage, websocket.FormatCloseMessage(websocket.CloseGoingAway, err.Error()), time.Time{})
+				if err != nil {
+					log.Println("[ERROR] WriteControl failed: ", err)
+				}
 				return
 			}
 		case <-done:

caddytls/setup.go

@@ -36,7 +36,9 @@ import (
 func init() {
 	// opt-in TLS 1.3 for Go1.12
 	// TODO: remove this line when Go1.13 is released.
-	os.Setenv("GODEBUG", os.Getenv("GODEBUG")+",tls13=1")
+	if err := os.Setenv("GODEBUG", os.Getenv("GODEBUG")+",tls13=1"); err != nil {
+		log.Println("[ERROR] failed to set environment variable: ", err)
+	}
 
 	caddy.RegisterPlugin("tls", caddy.Plugin{Action: setupTLS})
 
@@ -409,26 +411,34 @@ func loadCertsInDir(cfg *Config, c *caddy.Controller, dir string) error {
 
 				if derBlock.Type == "CERTIFICATE" {
 					// Re-encode certificate as PEM, appending to certificate chain
-					pem.Encode(certBuilder, derBlock)
+					if err := pem.Encode(certBuilder, derBlock); err != nil {
+						log.Println("[ERROR] failed to write PEM encoding: ", err)
+					}
 				} else if derBlock.Type == "EC PARAMETERS" {
 					// EC keys generated from openssl can be composed of two blocks:
 					// parameters and key (parameter block should come first)
 					if !foundKey {
 						// Encode parameters
-						pem.Encode(keyBuilder, derBlock)
+						if err := pem.Encode(keyBuilder, derBlock); err != nil {
+							log.Println("[ERROR] failed to write PEM encoding: ", err)
+						}
 
 						// Key must immediately follow
 						derBlock, bundle = pem.Decode(bundle)
 						if derBlock == nil || derBlock.Type != "EC PRIVATE KEY" {
 							return c.Errf("%s: expected elliptic private key to immediately follow EC parameters", path)
 						}
-						pem.Encode(keyBuilder, derBlock)
+						if err := pem.Encode(keyBuilder, derBlock); err != nil {
+							log.Println("[ERROR] failed to write PEM encoding: ", err)
+						}
 						foundKey = true
 					}
 				} else if derBlock.Type == "PRIVATE KEY" || strings.HasSuffix(derBlock.Type, " PRIVATE KEY") {
 					// RSA key
 					if !foundKey {
-						pem.Encode(keyBuilder, derBlock)
+						if err := pem.Encode(keyBuilder, derBlock); err != nil {
+							log.Println("[ERROR] failed to write PEM encoding: ", err)
+						}
 						foundKey = true
 					}
 				} else {

telemetry/collection.go

@@ -283,7 +283,10 @@ func atomicAdd(key string, amount int) {
 // Do not use this for cryptographic purposes.
 func FastHash(input []byte) string {
 	h := fnv.New32a()
-	h.Write(input)
+	if _, err := h.Write(input); err != nil {
+		log.Println("[ERROR] failed to write bytes: ", err)
+	}
+
 	return fmt.Sprintf("%x", h.Sum32())
 }