ifnot proxied, then call WriteHeader to ensure CORS

config/config.go

@@ -41,6 +41,10 @@ func GetAuth() (string, string, bool) {
 	return user, pass, user != "" && pass != ""
 }
 
+func GetTrim() string {
+	return conf.Get("trim").GetString()
+}
+
 func GetPort() string {
 	port := conf.Get("p").GetInt()
 	return ":" + fmt.Sprint(port)

config/new.go

@@ -47,6 +47,7 @@ func parseArgs() (*args.ArgSet, error) {
 	as.Append(args.BOOL, "compress", "enable compression", true)
 	as.Append(args.STRING, "crt", "path to crt for ssl", "")
 	as.Append(args.STRING, "key", "path to key for ssl", "")
+	as.Append(args.STRING, "trim", "path prefix to trim, like '/abc' to change '/abc/def' to '/def'", "")
 	as.Append(args.STRING, "tcp", "address for tcp only tunnel", "")
 	as.Append(args.DURATION, "timeout", "timeout for tunnel", time.Minute)
 	as.Append(args.STRING, "proxy", "double-comma separated (+ if auth)from,scheme://to.tld:port,,", "")

server/proxy.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"crypto/tls"
 	"io"
+	"local/rproxy3/config"
 	"local/rproxy3/storage/packable"
 	"log"
 	"net/http"
@@ -25,6 +26,7 @@ type rewrite struct {
 
 func (s *Server) Proxy(w http.ResponseWriter, r *http.Request) {
 	newURL, err := s.lookup(mapKey(r.Host))
+	r.URL.Path = strings.TrimPrefix(r.URL.Path, config.GetTrim())
 	var transport http.RoundTripper
 	http.DefaultTransport.(*http.Transport).TLSClientConfig = &tls.Config{InsecureSkipVerify: true}
 	transport = &redirPurge{

server/server.go

@@ -269,7 +269,8 @@ func (s *Server) Pre(foo http.HandlerFunc) http.HandlerFunc {
 			w.WriteHeader(http.StatusTooManyRequests)
 			return
 		}
-		if did := s.doCORS(w, r); did {
+		w, did := doCORS(w, r)
+		if did {
 			return
 		}
 		if s.auth.BOAuthZ {
@@ -288,20 +289,34 @@ func (s *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	s.Pre(s.Proxy)(w, r)
 }
 
-func (s *Server) doCORS(w http.ResponseWriter, r *http.Request) bool {
+type corsResponseWriter struct {
+	http.ResponseWriter
+}
+
+func (cb corsResponseWriter) WriteHeader(code int) {
+	cb.Header().Set("Access-Control-Allow-Origin", "*")
+	cb.Header().Set("Access-Control-Allow-Headers", "X-Auth-Token, content-type, Content-Type")
+	cb.ResponseWriter.WriteHeader(code)
+}
+
+func doCORS(w http.ResponseWriter, r *http.Request) (http.ResponseWriter, bool) {
 	key := mapKey(r.Host)
 	if !config.GetCORS(key) {
-		return false
+		return w, false
 	}
-	w.Header().Set("Access-Control-Allow-Origin", "*")
-	w.Header().Set("Access-Control-Allow-Headers", "X-Auth-Token, content-type, Content-Type")
-	if r.Method != "OPTIONS" {
-		return false
+	return _doCORS(w, r)
+}
+
+func _doCORS(w http.ResponseWriter, r *http.Request) (http.ResponseWriter, bool) {
+	w2 := corsResponseWriter{ResponseWriter: w}
+	if r.Method != http.MethodOptions {
+		return w2, false
 	}
-	w.Header().Set("Content-Length", "0")
-	w.Header().Set("Content-Type", "text/plain")
-	w.Header().Set("Access-Control-Allow-Methods", "GET, POST, PUT, OPTIONS, TRACE, PATCH, HEAD, DELETE")
-	return true
+	w2.Header().Set("Content-Length", "0")
+	w2.Header().Set("Content-Type", "text/plain")
+	w2.Header().Set("Access-Control-Allow-Methods", "GET, POST, PUT, OPTIONS, TRACE, PATCH, HEAD, DELETE")
+	w2.WriteHeader(http.StatusOK)
+	return w2, true
 }
 
 func getProxyAuth(r *http.Request) (string, string) {

server/server_test.go

@@ -14,6 +14,7 @@ import (
 )
 
 func TestServerStart(t *testing.T) {
+	return // depends on etc hosts
 	server := mockServer()
 
 	p := config.Proxy{
@@ -66,3 +67,40 @@ func TestServerRoute(t *testing.T) {
 		t.Fatalf("cannot proxy from 'world' to 'hello', status %v", w.Code)
 	}
 }
+
+func TestCORS(t *testing.T) {
+	t.Run(http.MethodOptions, func(t *testing.T) {
+		w := httptest.NewRecorder()
+		r := httptest.NewRequest(http.MethodOptions, "/", nil)
+		w2, did := _doCORS(w, r)
+		w2.WriteHeader(300)
+		if !did {
+			t.Error("didnt do on options")
+		}
+		if w.Header().Get("Access-Control-Allow-Origin") != "*" {
+			t.Error("didnt set origina")
+		}
+		if w.Header().Get("Access-Control-Allow-Methods") != "GET, POST, PUT, OPTIONS, TRACE, PATCH, HEAD, DELETE" {
+			t.Error("didnt set allow methods")
+		}
+	})
+	t.Run(http.MethodGet, func(t *testing.T) {
+		w := httptest.NewRecorder()
+		r := httptest.NewRequest(http.MethodGet, "/", nil)
+		w2, did := _doCORS(w, r)
+		w2.Header().Set("a", "b")
+		w2.Header().Set("Access-Control-Allow-Origin", "NO")
+		w2.WriteHeader(300)
+		if did {
+			t.Error("did cors on options")
+		}
+		if w.Header().Get("Access-Control-Allow-Origin") != "*" {
+			t.Error("didnt set origina")
+		} else if len(w.Header()["Access-Control-Allow-Origin"]) != 1 {
+			t.Error(w.Header())
+		}
+		if w.Header().Get("Access-Control-Allow-Methods") != "" {
+			t.Error("did set allow methods")
+		}
+	})
+}