Take as self request if URL path seem like getting PAC.

pac.go

@@ -197,9 +197,10 @@ func initPAC() {
 	}()
 }
 
-func sendPAC(c *clientConn) {
-	if _, err := c.Write(genPAC(c)); err != nil {
-		debug.Println("Error sending PAC file")
-		return
+func sendPAC(c *clientConn) error {
+	_, err := c.Write(genPAC(c))
+	if err != nil {
+		debug.Printf("cli(%s) error sending PAC:", c.RemoteAddr(), err)
 	}
+	return err
 }

proxy.go

@@ -215,6 +215,12 @@ func isSelfRequest(r *Request) bool {
 	}
 	// Maxthon sometimes sends requests without host in request line,
 	// in that case, get host information from Host header.
+	// But if client PAC setting is using cow server's DNS name, we can't
+	// decide if the request is for cow itself (need reverse lookup).
+	// So if request path seems like getting PAC, simply return true.
+	if r.URL.Path == "/pac" || strings.HasPrefix(r.URL.Path, "/pac?") {
+		return true
+	}
 	r.URL.ParseHostPort(r.Header.Host)
 	if selfListenAddr[r.URL.Host] {
 		return true
@@ -229,7 +235,8 @@ func (c *clientConn) serveSelfURL(r *Request) (err error) {
 	}
 	if r.URL.Path == "/pac" || strings.HasPrefix(r.URL.Path, "/pac?") {
 		sendPAC(c)
-		// Send non nil error to close client connection.
+		// PAC header contains connection close, send non nil error to close
+		// client connection.
 		return errPageSent
 	}
 end: