From 71a9b231e3cf38a4fa7d7c881e7296634f6128d9 Mon Sep 17 00:00:00 2001
From: LowEel <e.fusi@reply.de@users.noreply.github.com>
Date: Fri, 30 Jul 2021 23:20:49 +0200
Subject: [PATCH] Protected map, better check for RCPT

---
 backend.go |  9 ++++++++-
 go.mod     |  5 +----
 go.sum     |  4 ----
 handler.go | 23 +++++++++++++++++++++++
 session.go | 10 +++-------
 5 files changed, 35 insertions(+), 16 deletions(-)

diff --git a/backend.go b/backend.go
index 81bb271..a04e742 100644
--- a/backend.go
+++ b/backend.go
@@ -5,6 +5,7 @@ import (
 	"log"
 	"os"
 	"strings"
+	"sync"
 )
 
 // The Backend implements SMTP server methods.
@@ -17,6 +18,8 @@ type Backend struct {
 
 var SmtpBackend *Backend
 
+var mutex = &sync.Mutex{}
+
 // Load Valid Recipients
 func (bkd *Backend) LoadValidRecipients() error {
 	bkd.MaxRecipients = 0
@@ -41,9 +44,13 @@ func (bkd *Backend) LoadValidRecipients() error {
 
 }
 
-// Checks if Mail is a valid recipient
+// Checks if Mail is a valid local recipient
 func (bkd *Backend) CheckValidRcpt(to string) bool {
 
+	defer mutex.Unlock()
+
+	mutex.Lock()
+
 	_, isValid := bkd.ValidRecipientsMap[to]
 
 	return isValid
diff --git a/go.mod b/go.mod
index e169c16..9f52936 100644
--- a/go.mod
+++ b/go.mod
@@ -2,7 +2,4 @@ module zangtumb
 
 go 1.13
 
-require (
-	github.com/amalfra/maildir v0.0.7
-	github.com/emersion/go-smtp v0.12.1 // indirect
-)
+require github.com/amalfra/maildir v0.0.7
diff --git a/go.sum b/go.sum
index 2020e77..d61835a 100644
--- a/go.sum
+++ b/go.sum
@@ -1,6 +1,2 @@
 github.com/amalfra/maildir v0.0.7 h1:quK6vVGmjqP1zbeo9g7jtx37htGoYrKKlSpcDcplD04=
 github.com/amalfra/maildir v0.0.7/go.mod h1:+ynYowCpUHTWebUhg3Sb6Jp2dq+SUSWLTSLIf7Vy+ak=
-github.com/emersion/go-sasl v0.0.0-20190817083125-240c8404624e h1:ba7YsgX5OV8FjGi5ZWml8Jng6oBrJAb3ahqWMJ5Ce8Q=
-github.com/emersion/go-sasl v0.0.0-20190817083125-240c8404624e/go.mod h1:G/dpzLu16WtQpBfQ/z3LYiYJn3ZhKSGWn83fyoyQe/k=
-github.com/emersion/go-smtp v0.12.1 h1:1R8BDqrR2HhlGwgFYcOi+BVTvK1bMjAB65QcVpJ5sNA=
-github.com/emersion/go-smtp v0.12.1/go.mod h1:SD9V/xa4ndMw77lR3Mf7htkp8RBNYuPh9UeuBs9tpUQ=
diff --git a/handler.go b/handler.go
index 44a8835..d0ba17b 100644
--- a/handler.go
+++ b/handler.go
@@ -4,8 +4,14 @@ import (
 	"bytes"
 	"log"
 	"net"
+    "time"
 )
 
+func init() {
+	ZangSmtpServer.HandlerRcpt = handlerRcpt
+}
+
+
 func mailHandler(origin net.Addr, from string, to []string, data []byte) {
 	SmtpSession := new(Session)
 
@@ -28,3 +34,20 @@ func mailHandler(origin net.Addr, from string, to []string, data []byte) {
 	}
 
 }
+
+
+func handlerRcpt(remoteAddr net.Addr, from string, to string) bool {
+
+	log.Println("CHECK #2 Rcpt to:", to)
+	if !SmtpBackend.CheckValidRcpt(to) {
+		log.Printf("%s [ %s -> $s ] %s BAD!!!!", "YU NO MAIL!!! WE NU RELAY!!! ", from, to, remoteAddr.String() )
+		time.Sleep(10 * time.Second)
+		return false
+	}else{
+		log.Printf("%s [ %s -> $s ] %s GOOD!!!!", "WE DO!!!", from, to, remoteAddr.String() )
+	}
+
+	return true
+
+
+}
\ No newline at end of file
diff --git a/session.go b/session.go
index c5215c5..7087fc1 100644
--- a/session.go
+++ b/session.go
@@ -1,13 +1,13 @@
 package main
 
 import (
-	"errors"
+	
 	"fmt"
 	"io"
 	"io/ioutil"
 	"log"
 	"strings"
-	"time"
+	
 
 	"github.com/amalfra/maildir"
 )
@@ -22,11 +22,7 @@ type Session struct {
 }
 
 func (s *Session) Rcpt(to string) error {
-	log.Println("Rcpt to:", to)
-	if !SmtpBackend.CheckValidRcpt(to) {
-		time.Sleep(10 * time.Second)
-		return errors.New("YU NO MAIL!!! WE NU RELAY")
-	}
+	log.Println("CHECK #1 Rcpt to:", to)
 	s.RcptTo = to
 	if strings.Contains(to, "@") {
 		rcptArray := strings.Split(to, "@")