Allow to adjust TLS configuration

Needed when the SMTP server is obsolete.

config/config.go

@@ -1,9 +1,12 @@
 package config
 
 import (
+	"crypto/tls"
+
 	"github.com/spf13/afero"
 	"github.com/spf13/viper"
 
+	"errors"
 	"fmt"
 	"runtime"
 	"strings"
@@ -58,6 +61,27 @@ type SMTPConfig struct {
 	URL  string
 	User string
 	Pass string
+	TLS  TLSConfig
+}
+
+type TLSConfig struct {
+	InsecureSkipVerify bool
+	MinVersion         string
+}
+
+func (t TLSConfig) GetMinVersion() (uint16, error) {
+	switch t.MinVersion {
+	case "1.0":
+		return tls.VersionTLS10, nil
+	case "1.1":
+		return tls.VersionTLS11, nil
+	case "1.2":
+		return tls.VersionTLS12, nil
+	case "1.3":
+		return tls.VersionTLS13, nil
+	default:
+		return 0, errors.New("Invalid TLS version")
+	}
 }
 
 // Initial blank config
@@ -115,6 +139,8 @@ func newViperConfig(fs afero.Fs) *viper.Viper {
 	v.SetDefault("smtp.url", "")
 	v.SetDefault("smtp.user", "")
 	v.SetDefault("smtp.pass", "")
+	v.SetDefault("smtp.tls.InsecureSkipVerify", false)
+	v.SetDefault("smtp.tls.MinVersion", "1.2")
 	v.SetDefault("dryRun", false)
 
 	// Defaults (Dirs)

config/config_test.go

@@ -0,0 +1,57 @@
+package config
+
+import (
+	"crypto/tls"
+	"path/filepath"
+	"testing"
+
+	"github.com/spf13/afero"
+)
+
+func TestDefaultConfig(t *testing.T) {
+	cfg := NewConfig(afero.NewMemMapFs())
+
+	// Write and load fake configuration
+	cPath, _ := filepath.Abs("./config.toml")
+	afero.WriteFile(cfg.AppFs, cPath, []byte(""), 0644)
+	if err := LoadConfigTo(cfg); err != nil {
+		panic(err)
+	}
+
+	version, err := cfg.ConfigFile.SMTP.TLS.GetMinVersion()
+	if err != nil {
+		t.Error(err)
+	}
+	if version != tls.VersionTLS12 {
+		t.Errorf("Invalid version: expected %d got %d", tls.VersionTLS12, version)
+	}
+	if cfg.ConfigFile.SMTP.TLS.InsecureSkipVerify {
+		t.Error("InsecureSkipVerify should be false")
+	}
+}
+
+func TestTLSConfig(t *testing.T) {
+	cfg := NewConfig(afero.NewMemMapFs())
+
+	// Write and load fake configuration
+	cPath, _ := filepath.Abs("./config.toml")
+	afero.WriteFile(cfg.AppFs, cPath, []byte(`
+[smtp.tls]
+InsecureSkipVerify = true
+MinVersion = "1.0"
+	`), 0644)
+	if err := LoadConfigTo(cfg); err != nil {
+		panic(err)
+	}
+
+	version, err := cfg.ConfigFile.SMTP.TLS.GetMinVersion()
+	if err != nil {
+		t.Error(err)
+	}
+	if version != tls.VersionTLS10 {
+		t.Errorf("Invalid version: expected %d got %d", tls.VersionTLS12, version)
+	}
+	if !cfg.ConfigFile.SMTP.TLS.InsecureSkipVerify {
+		t.Error("InsecureSkipVerify should be true")
+	}
+}

mail/sender.go

@@ -1,6 +1,8 @@
 package mail
 
 import (
+	"crypto/tls"
+
 	"github.com/cenkalti/backoff/v4"
 	"github.com/go-gomail/gomail"
 	"github.com/rykov/paperboy/config"
@@ -236,6 +238,15 @@ func smtpDialer(cfg *config.SMTPConfig) (*gomail.Dialer, error) {
 	// Initialize the dialer
 	d := gomail.NewDialer(surl.Hostname(), port, user, pass)
 	d.SSL = (surl.Scheme == "smtps")
+	// insecure TLSConfig
+	tlsMinVersion, err := cfg.TLS.GetMinVersion()
+	if err != nil {
+		return nil, err
+	}
+	d.TLSConfig = &tls.Config{
+		InsecureSkipVerify: cfg.TLS.InsecureSkipVerify,
+		MinVersion:         tlsMinVersion,
+	}
 	return d, nil
 }