From 7b6be951250bc748d4e498e34e206e849d7d6a13 Mon Sep 17 00:00:00 2001
From: Aivars Sterns <asterns@onairent.live>
Date: Wed, 29 Oct 2025 11:50:30 +0200
Subject: [PATCH] feat: add alias file support

---
 aliases.go    | 52 +++++++++++++++++++++++++++++++++++++++++++++++++++
 config.go     | 17 +++++++++++++++++
 main.go       | 11 +++++++++++
 smtp.go       |  2 +-
 smtprelay.ini | 10 +++++++---
 5 files changed, 88 insertions(+), 4 deletions(-)
 create mode 100644 aliases.go

diff --git a/aliases.go b/aliases.go
new file mode 100644
index 0000000..7ff27ae
--- /dev/null
+++ b/aliases.go
@@ -0,0 +1,52 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"strings"
+)
+
+type AliasMap map[string]string
+
+func AliasLoadFile(file string) (AliasMap, error) {
+	aliasMap := make(AliasMap)
+	count := 0
+	log.Info().
+		Str("file", file).
+		Msg("Loading aliases file")
+
+	f, err := os.Open(file)
+	if err != nil {
+		log.Fatal().
+			Str("file", file).
+			Err(err).
+			Msg("cannot load aliases file")
+	}
+	defer f.Close()
+
+	scanner := bufio.NewScanner(f)
+	for scanner.Scan() {
+		line := strings.TrimSpace(scanner.Text())
+		if line == "" {
+			continue
+		}
+
+		parts := strings.Fields(line)
+		if len(parts) >= 2 {
+			aliasMap[parts[0]] = parts[1]
+			count++
+		}
+	}
+	log.Info().
+		Str("file", file).
+		Msg(fmt.Sprintf("Loaded %d aliases from file", count))
+
+	if err := scanner.Err(); err != nil {
+		log.Fatal().
+			Str("file", file).
+			Err(err).
+			Msg("cannot load aliases file")
+	}
+	return aliasMap, nil
+}
diff --git a/config.go b/config.go
index ac0ddb1..4c0e65e 100644
--- a/config.go
+++ b/config.go
@@ -42,6 +42,7 @@ var (
 	allowedSenderStr = flagset.String("allowed_sender", "", "Regular expression for valid FROM EMail addresses")
 	allowedRecipStr  = flagset.String("allowed_recipients", "", "Regular expression for valid TO EMail addresses")
 	allowedUsers     = flagset.String("allowed_users", "", "Path to file with valid users/passwords")
+	aliasesFile      = flagset.String("aliases_file", "", "Path to aliases file")
 	command          = flagset.String("command", "", "Path to pipe command")
 	remotesStr       = flagset.String("remotes", "", "Outgoing SMTP servers")
 	strictSender     = flagset.Bool("strict_sender", false, "Use only SMTP servers with Sender matches to From")
@@ -59,12 +60,27 @@ var (
 	allowedSender     *regexp.Regexp
 	allowedRecipients *regexp.Regexp
 	remotes           = []*Remote{}
+	aliasesList       = AliasMap{}
 )
 
 func localAuthRequired() bool {
 	return *allowedUsers != ""
 }
 
+func setupAliases() {
+	if *aliasesFile != "" {
+		aliases := make(AliasMap)
+		aliases, err := AliasLoadFile(*aliasesFile)
+		if err != nil {
+			log.Fatal().
+				Str("file", *aliasesFile).
+				Err(err).
+				Msg("cannot load aliases file")
+		}
+		aliasesList = aliases
+	}
+}
+
 func setupAllowedNetworks() {
 	for _, netstr := range splitstr(*allowedNetsStr, ' ') {
 		baseIP, allowedNet, err := net.ParseCIDR(netstr)
@@ -240,6 +256,7 @@ func ConfigLoad() {
 
 	setupAllowedNetworks()
 	setupAllowedPatterns()
+	setupAliases()
 	setupRemotes()
 	setupListeners()
 	setupTimeouts()
diff --git a/main.go b/main.go
index aa4e306..0d8735a 100644
--- a/main.go
+++ b/main.go
@@ -159,6 +159,17 @@ func mailHandler(peer smtpd.Peer, env smtpd.Envelope) error {
 		peerIP = addr.IP.String()
 	}
 
+	// Check for aliases
+	for i, recipient := range env.Recipients {
+		if alias, exists := aliasesList[recipient]; exists {
+			env.Recipients[i] = alias
+			log.Info().
+				Str("original_recipient", recipient).
+				Str("aliased_recipient", alias).
+				Msg("Recipient address aliased")
+		}
+	}
+
 	logger := log.With().
 		Str("from", env.Sender).
 		Strs("to", env.Recipients).
diff --git a/smtp.go b/smtp.go
index 628e124..bee2bf1 100644
--- a/smtp.go
+++ b/smtp.go
@@ -200,7 +200,7 @@ func (c *Client) Auth(a smtp.Auth) error {
 		return err
 	}
 	encoding := base64.StdEncoding
-	mech, resp, err := a.Start(&smtp.ServerInfo{c.serverName, c.tls, c.auth})
+	mech, resp, err := a.Start(&smtp.ServerInfo{Name: c.serverName, TLS: c.tls, Auth: c.auth})
 	if err != nil {
 		c.Quit()
 		return err
diff --git a/smtprelay.ini b/smtprelay.ini
index a7183ee..93187ff 100644
--- a/smtprelay.ini
+++ b/smtprelay.ini
@@ -8,10 +8,13 @@
 ;logfile = 
 
 ; Log format: default, plain (no timestamp), json
-;log_format = default
+log_format = default
 
 ; Log level: panic, fatal, error, warn, info, debug, trace
-;log_level = info
+log_level = info
+
+; path to alias file
+aliases_file = aliases.txt
 
 ; Hostname for this SMTP server
 ;hostname = localhost.localdomain
@@ -21,7 +24,8 @@
 
 ; Listen on the following addresses for incoming
 ; unencrypted connections.
-;listen = 127.0.0.1:25 [::1]:25
+listen = 127.0.0.1:8025 
+#[::1]:25
 
 ; STARTTLS and TLS are also supported but need a
 ; SSL certificate and key.