docs: Add catch-all recipient configuration to README

.gitignore

@@ -31,3 +31,4 @@ dist/
 
 # smtp2shoutrrr
 config.toml
+.aider*

Containerfile

@@ -1,3 +1,5 @@
+# This file is used directly by the goreleaser build
+# It is used to build the final container image
 FROM scratch
 COPY /smtp2shoutrrr /usr/bin/smtp2shoutrrr
 ENTRYPOINT ["/usr/bin/smtp2shoutrrr"]

Makefile

@@ -12,7 +12,6 @@ CGO_ENABLED := 0
 BUILDS_PATH := ./dist
 FROM_MAKEFILE := y
 
-CONTAINER_RUNTIME := podman
 CONTAINERFILE_NAME := Containerfile
 CONTAINER_ALPINE_VERSION := 3.20
 CONTAINER_SOURCE_URL := "https://git.nakama.town/fmartingr/${PROJECT_NAME}"
@@ -31,7 +30,6 @@ export TEST_OPTIONS
 export TEST_TIMEOUT
 export BUILDS_PATH
 
-export CONTAINER_RUNTIME
 export CONTAINERFILE_NAME
 export CONTAINER_ALPINE_VERSION
 export CONTAINER_SOURCE_URL

README.md

@@ -24,6 +24,11 @@ Addresses = ["some@email.com"]
 Target = "ntfy://ntfy.sh/my-ntfy-topic?tags=thing"
 
 # Note: Repeat [[Recipients]] as needed
+
+# Optional: Configure a catch-all recipient for unmatched email addresses
+[CatchAll]
+# Shoutrrr service to forward unmatched emails to
+Target = "ntfy://ntfy.sh/catch-all-topic?tags=unmatched"
 ```
 
 ### From releases

backend.go

@@ -0,0 +1,142 @@
+package smtp2shoutrrr
+
+import (
+	"fmt"
+	"io"
+	"log/slog"
+	"net/mail"
+	"net/url"
+	"slices"
+	"strings"
+
+	"github.com/containrrr/shoutrrr"
+	"github.com/emersion/go-sasl"
+	"github.com/emersion/go-smtp"
+)
+
+type Backend struct {
+	config *Config
+}
+
+func (bkd *Backend) sendNotification(recipient ConfigRecipient, email ReceivedEmail) error {
+	if recipient.Target == "" {
+		slog.Warn("no target provided for recipient", slog.String("recipient", strings.Join(recipient.Addresses, ",")))
+		return nil
+	}
+
+	urlParams := url.Values{
+		"title": {email.Msg.Header.Get("Subject")},
+	}
+
+	destinationURL := recipient.GetTargetURL()
+	destinationURL.RawQuery = urlParams.Encode()
+
+	body, err := email.Body()
+	if err != nil {
+		slog.Error("Error getting email body", slog.String("err", err.Error()))
+		return fmt.Errorf("failed to get email body: %w", err)
+	}
+
+	if err := shoutrrr.Send(destinationURL.String(), body); err != nil {
+		slog.Error("Error sending message", slog.String("err", err.Error()))
+		return fmt.Errorf("failed to send notification: %w", err)
+	}
+
+	return nil
+}
+
+func (bkd *Backend) NewSession(c *smtp.Conn) (smtp.Session, error) {
+	return &Session{
+		forwarderFunc: bkd.forwardEmail,
+		config:        bkd.config,
+	}, nil
+}
+
+func (bkd *Backend) forwardEmail(email ReceivedEmail) error {
+	slog.Info("forwading message", slog.String("to", strings.Join(email.Recipients, ",")))
+
+	// Try to match configured recipients first
+	matched := false
+	for _, r := range bkd.config.Recipients {
+		for _, a := range email.Recipients {
+			if slices.Contains(r.Addresses, a) {
+				if err := bkd.sendNotification(r, email); err != nil {
+					return err
+				}
+				matched = true
+				break
+			}
+		}
+		if matched {
+			break
+		}
+	}
+
+	// If no recipient matched and catch-all is configured, use it
+	if !matched && bkd.config.CatchAll != nil {
+		slog.Info("using catch-all recipient for unmatched email")
+		if err := bkd.sendNotification(*bkd.config.CatchAll, email); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+type Session struct {
+	addresses []string
+	body      string
+
+	config *Config
+
+	forwarderFunc func(ReceivedEmail) error
+}
+
+func (s *Session) AuthMechanisms() []string {
+	return []string{sasl.Plain}
+}
+
+func (s *Session) Auth(mech string) (sasl.Server, error) {
+	return sasl.NewPlainServer(func(identity, username, password string) error {
+		if username != s.config.Username && password != s.config.Password {
+			return fmt.Errorf("invalid credentials")
+		}
+		return nil
+	}), nil
+}
+
+func (s *Session) Mail(from string, opts *smtp.MailOptions) error {
+	slog.Debug("Mail from", slog.String("from", from))
+	return nil
+}
+
+func (s *Session) Rcpt(to string, opts *smtp.RcptOptions) error {
+	slog.Debug("Rcpt to", slog.String("to", to))
+	s.addresses = append(s.addresses, to)
+	return nil
+}
+
+func (s *Session) Data(r io.Reader) error {
+	msg, err := mail.ReadMessage(r)
+	if err != nil {
+		slog.Error("Error reading data", slog.String("err", err.Error()))
+		return fmt.Errorf("Error reading data: %w", err)
+	}
+
+	slog.Info("Received email", slog.String("destination", strings.Join(s.addresses, ",")))
+
+	if err := s.forwarderFunc(ReceivedEmail{
+		Recipients: s.addresses,
+		Msg:        msg,
+	}); err != nil {
+		slog.Error("Error forwarding email", slog.String("err", err.Error()))
+	}
+
+	return nil
+}
+
+func (s *Session) Reset() {}
+
+func (s *Session) Logout() error {
+	return nil
+}

cmd/smtp2shoutrrr/main.go

@@ -1,236 +1,16 @@
 package main
 
 import (
-	"bytes"
 	"context"
-	"fmt"
-	"io"
-	"log"
 	"log/slog"
-	"mime"
-	"mime/multipart"
-	"net/mail"
-	"net/url"
 	"os"
-	"slices"
-	"strings"
-	"time"
 
 	"git.nakama.town/fmartingr/gotoolkit/encoding"
 	"git.nakama.town/fmartingr/gotoolkit/model"
 	"git.nakama.town/fmartingr/gotoolkit/service"
-	"github.com/containrrr/shoutrrr"
-	"github.com/emersion/go-sasl"
-	"github.com/emersion/go-smtp"
-
 	"git.nakama.town/fmartingr/smtp2shoutrrr"
 )
 
-type ReceivedEmail struct {
-	Recipients []string
-	Msg        *mail.Message
-	body       string
-}
-
-func (re *ReceivedEmail) Body() (string, error) {
-	if re.body == "" {
-		// Get the Content-Type header
-		contentType := re.Msg.Header.Get("Content-Type")
-
-		if contentType == "" {
-			body, err := io.ReadAll(re.Msg.Body)
-			if err != nil {
-				return "", fmt.Errorf("failed to read email body: %w", err)
-			}
-			re.body = string(body)
-		} else {
-			mediaType, params, err := mime.ParseMediaType(contentType)
-			if err != nil {
-				log.Fatalf("Failed to parse Content-Type: %v", err)
-			}
-
-			if strings.HasPrefix(mediaType, "multipart/alternative") {
-				// Parse the multipart message
-				mr := multipart.NewReader(re.Msg.Body, params["boundary"])
-				for {
-					part, err := mr.NextPart()
-					if err != nil {
-						break // End of parts
-					}
-					defer part.Close()
-
-					// Print part headers
-					fmt.Printf("Part Content-Type: %s\n", part.Header.Get("Content-Type"))
-
-					// Set body if this is the text/plain part
-					if strings.HasPrefix(part.Header.Get("Content-Type"), "text/plain") {
-						// Read the part's body
-						body := new(bytes.Buffer)
-						_, err = body.ReadFrom(part)
-						if err != nil {
-							slog.Error("Failed to read part body", slog.String("err", err.Error()))
-							return "", fmt.Errorf("failed to read part body: %w", err)
-						}
-
-						re.body = body.String()
-						break
-					}
-				}
-			}
-		}
-	}
-
-	return re.body, nil
-}
-
-var _ model.Server = (*smtpServer)(nil)
-
-type smtpServer struct {
-	backend *smtp.Server
-	config  smtp2shoutrrr.Config
-}
-
-func (s *smtpServer) IsEnabled() bool {
-	return true
-}
-
-func (s *smtpServer) Start(_ context.Context) error {
-	slog.Info("Started SMTP server", slog.String("addr", s.backend.Addr))
-	return s.backend.ListenAndServe()
-}
-
-func (s *smtpServer) Stop(ctx context.Context) error {
-	slog.Info("Stopping SMTP server")
-	return s.backend.Shutdown(ctx)
-}
-
-func NewSMTPServer(config *smtp2shoutrrr.Config) model.Server {
-	be := &Backend{
-		config: config,
-	}
-
-	smtpBackend := smtp.NewServer(be)
-	smtpBackend.Addr = fmt.Sprintf(":%d", config.Port)
-	// smtpBackend.Domain = "localhost"
-	smtpBackend.WriteTimeout = 10 * time.Second
-	smtpBackend.ReadTimeout = 10 * time.Second
-	smtpBackend.MaxMessageBytes = 1024 * 1024
-	smtpBackend.MaxRecipients = 50
-	smtpBackend.AllowInsecureAuth = true
-
-	return &smtpServer{
-		backend: smtpBackend,
-	}
-}
-
-// The Backend implements SMTP server methods.
-type Backend struct {
-	config *smtp2shoutrrr.Config
-}
-
-// NewSession is called after client greeting (EHLO, HELO).
-func (bkd *Backend) NewSession(c *smtp.Conn) (smtp.Session, error) {
-	return &Session{
-		forwarderFunc: bkd.forwardEmail,
-		config:        bkd.config,
-	}, nil
-}
-
-func (bkd *Backend) forwardEmail(email ReceivedEmail) error {
-	slog.Info("forwading message", slog.String("to", strings.Join(email.Recipients, ",")))
-
-	for _, r := range bkd.config.Recipients {
-		for _, a := range email.Recipients {
-			if slices.Contains(r.Addresses, a) {
-				urlParams := url.Values{
-					"title": {email.Msg.Header.Get("Subject")},
-				}
-
-				destinationURL := r.GetTargetURL()
-				destinationURL.RawQuery = urlParams.Encode()
-
-				body, err := email.Body()
-				if err != nil {
-					slog.Error("Error getting email body", slog.String("err", err.Error()))
-					continue
-				}
-
-				if err := shoutrrr.Send(destinationURL.String(), body); err != nil {
-					slog.Error("Error sending message", slog.String("err", err.Error()))
-					continue
-				}
-
-				// Already sent via this configuration, go to the next
-				break
-			}
-		}
-	}
-
-	return nil
-}
-
-// A Session is returned after successful login.
-type Session struct {
-	addresses []string
-	body      string
-
-	config *smtp2shoutrrr.Config
-
-	forwarderFunc func(ReceivedEmail) error
-}
-
-// AuthMechanisms returns a slice of available auth mechanisms; only PLAIN is
-// supported in this example.
-func (s *Session) AuthMechanisms() []string {
-	return []string{sasl.Plain}
-}
-
-// Auth is the handler for supported authenticators.
-func (s *Session) Auth(mech string) (sasl.Server, error) {
-	return sasl.NewPlainServer(func(identity, username, password string) error {
-		if username != s.config.Username && password != s.config.Password {
-			return fmt.Errorf("invalid credentials")
-		}
-		return nil
-	}), nil
-}
-
-func (s *Session) Mail(from string, opts *smtp.MailOptions) error {
-	slog.Debug("Mail from", slog.String("from", from))
-	return nil
-}
-
-func (s *Session) Rcpt(to string, opts *smtp.RcptOptions) error {
-	slog.Debug("Rcpt to", slog.String("to", to))
-	s.addresses = append(s.addresses, to)
-	return nil
-}
-
-func (s *Session) Data(r io.Reader) error {
-	msg, err := mail.ReadMessage(r)
-	if err != nil {
-		slog.Error("Error reading data", slog.String("err", err.Error()))
-		return fmt.Errorf("Error reading data: %w", err)
-	}
-
-	slog.Info("Received email", slog.String("destination", strings.Join(s.addresses, ",")))
-
-	if err := s.forwarderFunc(ReceivedEmail{
-		Recipients: s.addresses,
-		Msg:        msg,
-	}); err != nil {
-		slog.Error("Error forwarding email", slog.String("err", err.Error()))
-	}
-
-	return nil
-}
-
-func (s *Session) Reset() {}
-
-func (s *Session) Logout() error {
-	return nil
-}
-
 func main() {
 	var config *smtp2shoutrrr.Config
 	configPath := "config.toml"
@@ -252,7 +32,7 @@ func main() {
 	slog.Info("config loaded", slog.Int("recipients", len(config.Recipients)))
 
 	ctx := context.Background()
-	smtpServer := NewSMTPServer(config)
+	smtpServer := smtp2shoutrrr.NewSMTPServer(config)
 
 	svc, err := service.NewService([]model.Server{
 		smtpServer,

config.go

@@ -10,6 +10,7 @@ type Config struct {
 	Username   string
 	Password   string
 	Recipients []ConfigRecipient
+	CatchAll   *ConfigRecipient
 }
 
 func (c *Config) SetDefaults() {

email.go

@@ -0,0 +1,65 @@
+package smtp2shoutrrr
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"log"
+	"log/slog"
+	"mime"
+	"mime/multipart"
+	"net/mail"
+	"strings"
+)
+
+type ReceivedEmail struct {
+	Recipients []string
+	Msg        *mail.Message
+	body       string
+}
+
+func (re *ReceivedEmail) Body() (string, error) {
+	if re.body == "" {
+		contentType := re.Msg.Header.Get("Content-Type")
+
+		if contentType == "" {
+			body, err := io.ReadAll(re.Msg.Body)
+			if err != nil {
+				return "", fmt.Errorf("failed to read email body: %w", err)
+			}
+			re.body = string(body)
+		} else {
+			mediaType, params, err := mime.ParseMediaType(contentType)
+			if err != nil {
+				log.Fatalf("Failed to parse Content-Type: %v", err)
+			}
+
+			if strings.HasPrefix(mediaType, "multipart/alternative") {
+				mr := multipart.NewReader(re.Msg.Body, params["boundary"])
+				for {
+					part, err := mr.NextPart()
+					if err != nil {
+						break
+					}
+					defer part.Close()
+
+					fmt.Printf("Part Content-Type: %s\n", part.Header.Get("Content-Type"))
+
+					if strings.HasPrefix(part.Header.Get("Content-Type"), "text/plain") {
+						body := new(bytes.Buffer)
+						_, err = body.ReadFrom(part)
+						if err != nil {
+							slog.Error("Failed to read part body", slog.String("err", err.Error()))
+							return "", fmt.Errorf("failed to read part body: %w", err)
+						}
+
+						re.body = body.String()
+						break
+					}
+				}
+			}
+		}
+	}
+
+	return re.body, nil
+}

server.go

@@ -0,0 +1,50 @@
+package smtp2shoutrrr
+
+import (
+	"context"
+	"fmt"
+	"log/slog"
+	"time"
+
+	"git.nakama.town/fmartingr/gotoolkit/model"
+	"github.com/emersion/go-smtp"
+)
+
+var _ model.Server = (*smtpServer)(nil)
+
+type smtpServer struct {
+	backend *smtp.Server
+	config  Config
+}
+
+func (s *smtpServer) IsEnabled() bool {
+	return true
+}
+
+func (s *smtpServer) Start(_ context.Context) error {
+	slog.Info("Started SMTP server", slog.String("addr", s.backend.Addr))
+	return s.backend.ListenAndServe()
+}
+
+func (s *smtpServer) Stop(ctx context.Context) error {
+	slog.Info("Stopping SMTP server")
+	return s.backend.Shutdown(ctx)
+}
+
+func NewSMTPServer(config *Config) model.Server {
+	be := &Backend{
+		config: config,
+	}
+
+	smtpBackend := smtp.NewServer(be)
+	smtpBackend.Addr = fmt.Sprintf(":%d", config.Port)
+	smtpBackend.WriteTimeout = 10 * time.Second
+	smtpBackend.ReadTimeout = 10 * time.Second
+	smtpBackend.MaxMessageBytes = 1024 * 1024
+	smtpBackend.MaxRecipients = 50
+	smtpBackend.AllowInsecureAuth = true
+
+	return &smtpServer{
+		backend: smtpBackend,
+	}
+}