test: Add smtp-send utility

Small program to simulate external SMTP send to Bridge.

.golangci.yml

@@ -36,6 +36,14 @@ issues:
         - gosec
         - goconst
         - dogsled
+    - path: utils/smtp-send
+      linters:
+        - dupl
+        - gochecknoglobals
+        - gochecknoinits
+        - gosec
+        - goconst
+        - dogsled
 
 linters-settings:
   godox:

utils/smtp-send/main.go

@@ -0,0 +1,91 @@
+// Copyright (c) 2023 Proton AG
+//
+// This file is part of Proton Mail Bridge.
+//
+// Proton Mail Bridge is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Proton Mail Bridge is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Proton Mail Bridge.  If not, see <https://www.gnu.org/licenses/>.
+
+package main
+
+import (
+	"bytes"
+	"crypto/tls"
+	"flag"
+	"fmt"
+	"os"
+
+	"github.com/emersion/go-sasl"
+	"github.com/emersion/go-smtp"
+)
+
+var (
+	serverURL    = flag.String("server", "127.0.0.1:1025", "SMTP server address:port")
+	userName     = flag.String("user-name", "user", "SMTP user name")
+	userPassword = flag.String("user-pwd", "password", "SMTP user password")
+	toAddr       = flag.String("toAddr", "", "Address toAddr whom toAddr send the message")
+)
+
+func main() {
+	flag.Parse()
+	flag.Usage = func() {
+		fmt.Printf("Usage %v [options] file0 ... fileN\n", os.Args[0])
+		fmt.Printf("\nOptions:\n")
+		flag.PrintDefaults()
+	}
+
+	if len(*toAddr) == 0 {
+		panic(fmt.Errorf("to flag can't be empty"))
+	}
+
+	args := flag.Args()
+	if len(args) == 0 {
+		flag.Usage()
+		return
+	}
+
+	smtpClient, err := smtp.Dial(*serverURL)
+	if err != nil {
+		panic(fmt.Errorf("failed to connect to server: %w", err))
+	}
+	defer func() { _ = smtpClient.Close() }()
+
+	// Upgrade to TLS.
+	if err := smtpClient.StartTLS(&tls.Config{InsecureSkipVerify: true}); err != nil {
+		panic(fmt.Errorf("failed to starttls: %w", err))
+	}
+
+	// Authorize with SASL PLAIN.
+	if err := smtpClient.Auth(sasl.NewPlainClient(
+		*userName,
+		*userName,
+		*userPassword,
+	)); err != nil {
+		panic(fmt.Errorf("failed to login: %w", err))
+	}
+
+	for idx, v := range args {
+		fileData, err := os.ReadFile(v)
+		if err != nil {
+			panic(fmt.Errorf("failed to read file:%v - %w", v, err))
+		}
+
+		// Send the message.
+		if err := smtpClient.SendMail(
+			*userName,
+			[]string{*toAddr},
+			bytes.NewReader(fileData),
+		); err != nil {
+			panic(fmt.Errorf("failed to send msg %v: %w", idx, err))
+		}
+	}
+}