From ddffe0b7bfb1f124bfaf35386535194195fefa8e Mon Sep 17 00:00:00 2001
From: Robert Sesek <rsesek@bluestatic.org>
Date: Fri, 11 Nov 2022 14:17:55 -0500
Subject: [PATCH] Implement address blocking on the server.

---
 config.go    |  5 +++--
 smtp.go      | 19 ++++++++++++++++---
 smtp_test.go |  6 ++++++
 3 files changed, 25 insertions(+), 5 deletions(-)

diff --git a/config.go b/config.go
index c5f24ca..961d2cb 100644
--- a/config.go
+++ b/config.go
@@ -35,8 +35,9 @@ type Server struct {
 	// Location to store the mail messages.
 	MaildropPath string
 
-	// Blacklisted addresses that should not accept mail.
-	BlacklistedAddresses []string
+	// Addresses that should not accept mail. This should include the @domain
+	// component.
+	BlockedAddresses []string
 }
 
 func (c Config) GetTLSConfig() (*tls.Config, error) {
diff --git a/smtp.go b/smtp.go
index 4173d9b..c22728e 100644
--- a/smtp.go
+++ b/smtp.go
@@ -102,9 +102,15 @@ func (server *smtpServer) TLSConfig() *tls.Config {
 }
 
 func (server *smtpServer) VerifyAddress(addr mail.Address) smtp.ReplyLine {
-	if server.maildropForAddress(addr) == "" {
+	s := server.configForAddress(addr)
+	if s == nil {
 		return smtp.ReplyBadMailbox
 	}
+	for _, blocked := range s.BlockedAddresses {
+		if blocked == addr.Address {
+			return smtp.ReplyMailboxUnallowed
+		}
+	}
 	return smtp.ReplyOK
 }
 
@@ -150,14 +156,21 @@ func (server *smtpServer) DeliverMessage(en smtp.Envelope) *smtp.ReplyLine {
 	return nil
 }
 
-func (server *smtpServer) maildropForAddress(addr mail.Address) string {
+func (server *smtpServer) configForAddress(addr mail.Address) *Server {
 	domain := smtp.DomainForAddress(addr)
 	for _, s := range server.config.Servers {
 		if domain == s.Domain {
-			return s.MaildropPath
+			return &s
 		}
 	}
+	return nil
+}
 
+func (server *smtpServer) maildropForAddress(addr mail.Address) string {
+	s := server.configForAddress(addr)
+	if s != nil {
+		return s.MaildropPath
+	}
 	return ""
 }
 
diff --git a/smtp_test.go b/smtp_test.go
index ba8c254..b589c69 100644
--- a/smtp_test.go
+++ b/smtp_test.go
@@ -36,6 +36,9 @@ func TestVerifyAddress(t *testing.T) {
 				{
 					Domain:       "example.com",
 					MaildropPath: dir,
+					BlockedAddresses: []string{
+						"blocked@example.com",
+					},
 				},
 			},
 		},
@@ -57,6 +60,9 @@ func TestVerifyAddress(t *testing.T) {
 	if s.VerifyAddress(mail.Address{Address: "unknown"}) == smtp.ReplyOK {
 		t.Errorf("Invalid mailbox reports to be valid")
 	}
+	if s.VerifyAddress(mail.Address{Address: "blocked@example.com"}) == smtp.ReplyOK {
+		t.Errorf("Blocked mailbox reports to be valid")
+	}
 }
 
 func TestMessageDelivery(t *testing.T) {
-- 
2.22.5