Merge pull request #397 from goxiaoy/fix-admin-proxy

fix admin proxy

main.go

@@ -7,15 +7,18 @@
 package main
 
 import (
+	"bytes"
+	"compress/gzip"
 	"embed"
 	"fmt"
+	"io"
 	"io/fs"
-	"io/ioutil"
 	"net/http"
 	"net/http/httputil"
 	"net/url"
 	"os"
 	"os/signal"
+	"strconv"
 	"strings"
 	"syscall"
 
@@ -64,17 +67,13 @@ func addAdmin(app *gin.Engine, conf *config.Type) {
 		router = app.Group(conf.AdminBasePath)
 	}
 	if err == nil {
-		cont, err := ioutil.ReadAll(index)
+		cont, err := io.ReadAll(index)
 		logger.FatalIfError(err)
 		_ = index.Close()
-		sfile := string(cont)
+		cont = bytesTryReplaceIndex(cont, conf)
 
-		//replace base path
-		sfile = strings.Replace(sfile, "\"assets/", "\""+conf.AdminBasePath+"/assets/", -1)
-		sfile = strings.Replace(sfile, "PUBLIC-PATH-VARIABLE", conf.AdminBasePath, -1)
 		renderIndex := func(c *gin.Context) {
-			c.Header("content-type", "text/html;charset=utf-8")
-			c.String(200, sfile)
+			c.Data(200, "text/html; charset=utf-8", cont)
 		}
 		router.StaticFS("/assets", http.FS(getSub(dist, "assets")))
 		router.GET("/admin/*name", renderIndex)
@@ -84,9 +83,9 @@ func addAdmin(app *gin.Engine, conf *config.Type) {
 		})
 		logger.Infof("admin is served from dir 'admin/dist/'")
 	} else {
-		router.GET("/", proxyAdmin)
-		router.GET("/assets/*name", proxyAdmin)
-		router.GET("/admin/*name", proxyAdmin)
+		router.GET("/", proxyAdmin(conf))
+		router.GET("/assets/*name", proxyAdmin(conf))
+		router.GET("/admin/*name", proxyAdmin(conf))
 		lang := os.Getenv("LANG")
 		if strings.HasPrefix(lang, "zh_CN") {
 			target = "cn-admin.dtm.pub"
@@ -98,20 +97,79 @@ func addAdmin(app *gin.Engine, conf *config.Type) {
 	logger.Infof("admin is running at: http://localhost:%d%s", conf.HTTPPort, conf.AdminBasePath)
 }
 
-func proxyAdmin(c *gin.Context) {
+func proxyAdmin(conf *config.Type) func(c *gin.Context) {
+	return func(c *gin.Context) {
+		u := &url.URL{}
+		u.Scheme = "http"
+		u.Host = target
+		proxy := httputil.NewSingleHostReverseProxy(u)
+		originalDirector := proxy.Director
+		proxy.Director = func(r *http.Request) {
+			originalDirector(r)
+			p := strings.TrimPrefix(r.URL.Path, conf.AdminBasePath)
+			rp := strings.TrimPrefix(r.URL.RawPath, conf.AdminBasePath)
+			r.URL.Path = p
+			r.URL.RawPath = rp
+		}
+		proxy.Transport = &transport{RoundTripper: http.DefaultTransport, conf: conf}
+		proxy.ErrorHandler = func(rw http.ResponseWriter, req *http.Request, err error) {
+			logger.Warnf("http: proxy error: %v", err)
+			ret := fmt.Sprintf("http proxy error %v", err)
+			_, _ = rw.Write([]byte(ret))
+		}
+		logger.Debugf("proxy admin to %s", target)
+		c.Request.Host = target
+		proxy.ServeHTTP(c.Writer, c.Request)
+	}
 
-	u := &url.URL{}
-	u.Scheme = "http"
-	u.Host = target
-	proxy := httputil.NewSingleHostReverseProxy(u)
+}
 
-	proxy.ErrorHandler = func(rw http.ResponseWriter, req *http.Request, err error) {
-		logger.Warnf("http: proxy error: %v", err)
-		ret := fmt.Sprintf("http proxy error %v", err)
-		_, _ = rw.Write([]byte(ret))
-	}
-	logger.Debugf("proxy admin to %s", target)
-	c.Request.Host = target
-	proxy.ServeHTTP(c.Writer, c.Request)
+// bytesTryReplaceIndex replace index.html base path
+func bytesTryReplaceIndex(source []byte, conf *config.Type) []byte {
+	source = bytes.Replace(source, []byte("\"assets/"), []byte("\""+conf.AdminBasePath+"/assets/"), -1)
+	source = bytes.Replace(source, []byte("PUBLIC-PATH-VARIABLE"), []byte(conf.AdminBasePath), -1)
+	return source
+}
 
+type transport struct {
+	http.RoundTripper
+	conf *config.Type
+}
+
+func (t *transport) RoundTrip(req *http.Request) (resp *http.Response, err error) {
+	resp, err = t.RoundTripper.RoundTrip(req)
+	if err != nil {
+		return nil, err
+	}
+	//modify html only
+	if !strings.Contains(resp.Header.Get("Content-Type"), "text/html") {
+		return resp, err
+	}
+	var reader io.ReadCloser
+	switch resp.Header.Get("Content-Encoding") {
+	case "gzip":
+		reader, err = gzip.NewReader(resp.Body)
+		defer func() {
+			if tmpErr := reader.Close(); err == nil && tmpErr != nil {
+				err = tmpErr
+			}
+		}()
+	default:
+		reader = resp.Body
+	}
+	delete(resp.Header, "Content-Encoding")
+	b, err := io.ReadAll(reader)
+	if err != nil {
+		return nil, err
+	}
+	err = resp.Body.Close()
+	if err != nil {
+		return nil, err
+	}
+	b = bytesTryReplaceIndex(b, t.conf)
+	body := io.NopCloser(bytes.NewReader(b))
+	resp.Body = body
+	resp.ContentLength = int64(len(b))
+	resp.Header.Set("Content-Length", strconv.Itoa(len(b)))
+	return resp, nil
 }