added golangci-linting, refactor, simplified error msgs and fixed some error handling

internal/net/http/loadbalancer/loadbalancer.go

@@ -10,8 +10,8 @@ import (
 	E "github.com/yusing/go-proxy/internal/error"
 )
 
-// TODO: stats of each server
-// TODO: support weighted mode
+// TODO: stats of each server.
+// TODO: support weighted mode.
 type (
 	impl interface {
 		ServeHTTP(srvs servers, rw http.ResponseWriter, r *http.Request)

internal/net/http/middleware/custom_error_page.go

@@ -2,14 +2,14 @@ package middleware
 
 import (
 	"bytes"
-	"fmt"
 	"io"
 	"net/http"
 	"path/filepath"
+	"strconv"
 	"strings"
 
 	"github.com/sirupsen/logrus"
-	"github.com/yusing/go-proxy/internal/api/v1/error_page"
+	"github.com/yusing/go-proxy/internal/api/v1/errorpage"
 	gphttp "github.com/yusing/go-proxy/internal/net/http"
 )
 
@@ -23,14 +23,15 @@ var CustomErrorPage = &Middleware{
 		// only handles non-success status code and html/plain content type
 		contentType := gphttp.GetContentType(resp.Header)
 		if !gphttp.IsSuccess(resp.StatusCode) && (contentType.IsHTML() || contentType.IsPlainText()) {
-			errorPage, ok := error_page.GetErrorPageByStatus(resp.StatusCode)
+			errorPage, ok := errorpage.GetErrorPageByStatus(resp.StatusCode)
 			if ok {
 				errPageLogger.Debugf("error page for status %d loaded", resp.StatusCode)
+				/* trunk-ignore(golangci-lint/errcheck) */
 				io.Copy(io.Discard, resp.Body) // drain the original body
 				resp.Body.Close()
 				resp.Body = io.NopCloser(bytes.NewReader(errorPage))
 				resp.ContentLength = int64(len(errorPage))
-				resp.Header.Set("Content-Length", fmt.Sprint(len(errorPage)))
+				resp.Header.Set("Content-Length", strconv.Itoa(len(errorPage)))
 				resp.Header.Set("Content-Type", "text/html; charset=utf-8")
 			} else {
 				errPageLogger.Errorf("unable to load error page for status %d", resp.StatusCode)
@@ -48,25 +49,27 @@ func ServeStaticErrorPageFile(w http.ResponseWriter, r *http.Request) bool {
 	}
 	if strings.HasPrefix(path, gphttp.StaticFilePathPrefix) {
 		filename := path[len(gphttp.StaticFilePathPrefix):]
-		file, ok := error_page.GetStaticFile(filename)
+		file, ok := errorpage.GetStaticFile(filename)
 		if !ok {
 			errPageLogger.Errorf("unable to load resource %s", filename)
 			return false
-		} else {
-			ext := filepath.Ext(filename)
-			switch ext {
-			case ".html":
-				w.Header().Set("Content-Type", "text/html; charset=utf-8")
-			case ".js":
-				w.Header().Set("Content-Type", "application/javascript; charset=utf-8")
-			case ".css":
-				w.Header().Set("Content-Type", "text/css; charset=utf-8")
-			default:
-				errPageLogger.Errorf("unexpected file type %q for %s", ext, filename)
-			}
-			w.Write(file)
-			return true
 		}
+		ext := filepath.Ext(filename)
+		switch ext {
+		case ".html":
+			w.Header().Set("Content-Type", "text/html; charset=utf-8")
+		case ".js":
+			w.Header().Set("Content-Type", "application/javascript; charset=utf-8")
+		case ".css":
+			w.Header().Set("Content-Type", "text/css; charset=utf-8")
+		default:
+			errPageLogger.Errorf("unexpected file type %q for %s", ext, filename)
+		}
+		if _, err := w.Write(file); err != nil {
+			errPageLogger.WithError(err).Errorf("unable to write resource %s", filename)
+			http.Error(w, "Error page failure", http.StatusInternalServerError)
+		}
+		return true
 	}
 	return false
 }

internal/net/http/middleware/middleware_builder.go

@@ -30,7 +30,7 @@ func BuildMiddlewaresFromYAML(data []byte) (middlewares map[string]*Middleware,
 	}
 	middlewares = make(map[string]*Middleware)
 	for name, defs := range rawMap {
-		chainErr := E.NewBuilder(name)
+		chainErr := E.NewBuilder("%s", name)
 		chain := make([]*Middleware, 0, len(defs))
 		for i, def := range defs {
 			if def["use"] == nil || def["use"] == "" {
@@ -64,7 +64,7 @@ func BuildMiddlewaresFromYAML(data []byte) (middlewares map[string]*Middleware,
 	return
 }
 
-// TODO: check conflict or duplicates
+// TODO: check conflict or duplicates.
 func BuildMiddlewareFromChain(name string, chain []*Middleware) *Middleware {
 	m := &Middleware{name: name, children: chain}
 

internal/net/http/middleware/oauth2.go

@@ -92,18 +92,18 @@ func userIsAuthenticated(r *http.Request) bool {
 	return true
 }
 
-func exchangeCodeForToken(code string, opts *oAuth2Opts, requestUri string) (string, error) {
+func exchangeCodeForToken(code string, opts *oAuth2Opts, requestURI string) (string, error) {
 	// Prepare the request body
 	data := url.Values{
 		"client_id":     {opts.ClientID},
 		"client_secret": {opts.ClientSecret},
 		"code":          {code},
 		"grant_type":    {"authorization_code"},
-		"redirect_uri":  {requestUri},
+		"redirect_uri":  {requestURI},
 	}
 	resp, err := http.PostForm(opts.TokenURL, data)
 	if err != nil {
-		return "", fmt.Errorf("failed to request token: %v", err)
+		return "", fmt.Errorf("failed to request token: %w", err)
 	}
 	defer resp.Body.Close()
 	if resp.StatusCode != http.StatusOK {
@@ -114,7 +114,7 @@ func exchangeCodeForToken(code string, opts *oAuth2Opts, requestUri string) (str
 		AccessToken string `json:"access_token"`
 	}
 	if err := json.NewDecoder(resp.Body).Decode(&tokenResp); err != nil {
-		return "", fmt.Errorf("failed to decode token response: %v", err)
+		return "", fmt.Errorf("failed to decode token response: %w", err)
 	}
 	return tokenResp.AccessToken, nil
 }

internal/net/http/middleware/test_utils.go

@@ -74,7 +74,7 @@ type testArgs struct {
 
 func newMiddlewareTest(middleware *Middleware, args *testArgs) (*TestResult, E.NestedError) {
 	var body io.Reader
-	var rr = new(requestRecorder)
+	var rr requestRecorder
 	var proxyURL *url.URL
 	var requestTarget string
 	var err error
@@ -87,11 +87,14 @@ func newMiddlewareTest(middleware *Middleware, args *testArgs) (*TestResult, E.N
 		body = bytes.NewReader(args.body)
 	}
 
-	if args.scheme == "" || args.scheme == "http" {
+	switch args.scheme {
+	case "":
+		fallthrough
+	case "http":
 		requestTarget = "http://" + testHost
-	} else if args.scheme == "https" {
+	case "https":
 		requestTarget = "https://" + testHost
-	} else {
+	default:
 		panic("typo?")
 	}
 
@@ -111,7 +114,7 @@ func newMiddlewareTest(middleware *Middleware, args *testArgs) (*TestResult, E.N
 	} else {
 		proxyURL, _ = url.Parse("https://" + testHost) // dummy url, no actual effect
 	}
-	rp := gphttp.NewReverseProxy(types.NewURL(proxyURL), rr)
+	rp := gphttp.NewReverseProxy(types.NewURL(proxyURL), &rr)
 	mid, setOptErr := middleware.WithOptionsClone(args.middlewareOpt)
 	if setOptErr != nil {
 		return nil, setOptErr

internal/net/http/reverse_proxy_mod.go

@@ -24,10 +24,9 @@ import (
 	"sync"
 
 	"github.com/sirupsen/logrus"
-	"golang.org/x/net/http/httpguts"
-
 	"github.com/yusing/go-proxy/internal/net/types"
 	U "github.com/yusing/go-proxy/internal/utils"
+	"golang.org/x/net/http/httpguts"
 )
 
 // A ProxyRequest contains a request to be rewritten by a [ReverseProxy].
@@ -222,6 +221,7 @@ func (p *ReverseProxy) serveHTTP(rw http.ResponseWriter, req *http.Request) {
 	transport := p.Transport
 
 	ctx := req.Context()
+	/* trunk-ignore(golangci-lint/revive) */
 	if ctx.Done() != nil {
 		// CloseNotifier predates context.Context, and has been
 		// entirely superseded by it. If the request contains
@@ -460,7 +460,7 @@ func (p *ReverseProxy) handleUpgradeResponse(rw http.ResponseWriter, req *http.R
 
 	backConn, ok := res.Body.(io.ReadWriteCloser)
 	if !ok {
-		p.errorHandler(rw, req, fmt.Errorf("internal error: 101 switching protocols response with non-writable body"), true)
+		p.errorHandler(rw, req, errors.New("internal error: 101 switching protocols response with non-writable body"), true)
 		return
 	}
 
@@ -494,21 +494,24 @@ func (p *ReverseProxy) handleUpgradeResponse(rw http.ResponseWriter, req *http.R
 	res.Header = rw.Header()
 	res.Body = nil // so res.Write only writes the headers; we have res.Body in backConn above
 	if err := res.Write(brw); err != nil {
+		/* trunk-ignore(golangci-lint/errorlint) */
 		p.errorHandler(rw, req, fmt.Errorf("response write: %s", err), true)
 		return
 	}
 	if err := brw.Flush(); err != nil {
+		/* trunk-ignore(golangci-lint/errorlint) */
 		p.errorHandler(rw, req, fmt.Errorf("response flush: %s", err), true)
 		return
 	}
 
 	bdp := U.NewBidirectionalPipe(req.Context(), conn, backConn)
+	/* trunk-ignore(golangci-lint/errcheck) */
 	bdp.Start()
 }
 
 func IsPrint(s string) bool {
-	for i := 0; i < len(s); i++ {
-		if s[i] < ' ' || s[i] > '~' {
+	for _, r := range s {
+		if r < ' ' || r > '~' {
 			return false
 		}
 	}