add some validation for emails

Dockerfile

@@ -14,5 +14,5 @@ COPY --from=builder /build/smallweb /usr/local/bin/smallweb
 ENV SMALLWEB_DIR=/smallweb
 VOLUME ["$SMALLWEB_DIR"]
 
-EXPOSE 7777
-ENTRYPOINT ["/usr/local/bin/smallweb", "up", "--cron", "--addr", "0.0.0.0:7777"]
+EXPOSE 7777 2222 2525
+ENTRYPOINT ["/usr/local/bin/smallweb", "up", "--cron", "--http-addr", "0.0.0.0:7777", "--ssh-addr", "0.0.0.0:2222", "--smtp-addr", ":2525"]

cmd/up.go

@@ -1,6 +1,7 @@
 package cmd
 
 import (
+	"bytes"
 	"context"
 	"crypto/tls"
 	"errors"
@@ -10,6 +11,7 @@ import (
 	"log/slog"
 	"net"
 	"net/http"
+	"net/mail"
 	"os"
 	"os/exec"
 	"os/signal"
@@ -26,7 +28,7 @@ import (
 	"github.com/charmbracelet/keygen"
 	"github.com/charmbracelet/ssh"
 	"github.com/creack/pty"
-	"github.com/mhale/smtpd"
+	"github.com/emersion/go-smtp"
 	"github.com/pkg/sftp"
 	"github.com/pomdtr/smallweb/app"
 	"github.com/pomdtr/smallweb/watcher"
@@ -303,36 +305,25 @@ func NewCmdUp() *cobra.Command {
 			if flags.smtpAddr != "" {
 				fmt.Fprintf(os.Stderr, "Starting SMTP server on %s...\n", flags.smtpAddr)
 
-				handler := func(remoteAddr net.Addr, from string, to []string, data []byte) error {
-					for _, recipient := range to {
-						parts := strings.SplitN(recipient, "@", 2)
-						appname, domain := parts[0], parts[1]
-						if domain != k.String("domain") {
-							continue
-						}
+				server := smtp.NewServer(smtp.BackendFunc(func(c *smtp.Conn) (smtp.Session, error) {
+					return &SmtpSession{
+						conn: c,
+					}, nil
+				}))
 
-						a, err := app.LoadApp(appname, k.String("dir"), k.String("domain"), slices.Contains(k.Strings("adminApps"), appname))
-						if err != nil {
-							if errors.Is(err, app.ErrAppNotFound) {
-								continue
-							}
+				server.Addr = flags.smtpAddr
+				server.Domain = k.String("domain")
 
-							return fmt.Errorf("failed to load app: %v", err)
-						}
-
-						wk := worker.NewWorker(a)
-						if err := wk.SendEmail(context.Background(), strings.NewReader(string(data))); err != nil {
-							return fmt.Errorf("failed to send email: %v", err)
-						}
+				if flags.cert != "" && flags.key != "" {
+					cert, err := tls.LoadX509KeyPair(flags.cert, flags.key)
+					if err != nil {
+						return fmt.Errorf("failed to load cert: %v", err)
 					}
 
-					return nil
-				}
-
-				if flags.cert != "" && flags.key != "" {
-					go smtpd.ListenAndServeTLS(flags.smtpAddr, flags.cert, flags.key, handler, "Smallweb", k.String("domain"))
+					server.TLSConfig = &tls.Config{Certificates: []tls.Certificate{cert}}
+					go server.ListenAndServeTLS()
 				} else {
-					go smtpd.ListenAndServe(flags.smtpAddr, handler, "Smallweb", k.String("domain"))
+					go server.ListenAndServe()
 				}
 			}
 
@@ -500,3 +491,121 @@ func (me *Handler) GetWorker(appname, rootDir, domain string) (*worker.Worker, e
 	me.workers[appname] = wk
 	return wk, nil
 }
+
+type SmtpSession struct {
+	conn       *smtp.Conn
+	sender     string
+	recipients []string
+}
+
+func (s *SmtpSession) Reset() {
+	s.sender = ""
+	s.recipients = nil
+}
+
+func (s *SmtpSession) Mail(from string, opts *smtp.MailOptions) error {
+	s.sender = from
+
+	parts := strings.Split(from, "@")
+	if len(parts) != 2 {
+		return fmt.Errorf("invalid email format: %s", from)
+	}
+	senderDomain := parts[1]
+
+	clientAddr := s.conn.Conn().RemoteAddr().String()
+	clientIp, _, err := net.SplitHostPort(clientAddr)
+	if err != nil {
+		return fmt.Errorf("failed to parse client IP: %w", err)
+	}
+
+	// if client is localhost, allow
+	if clientIp == "::1" {
+		return nil
+	}
+
+	// Check A/AAAA records for the sender domain
+	domainIps, err := net.LookupIP(senderDomain)
+	if err == nil {
+		for _, ip := range domainIps {
+			if ip.String() == clientIp {
+				return nil
+			}
+		}
+	}
+
+	// Check MX records and resolve their IPs
+	mxRecords, err := net.LookupMX(senderDomain)
+	if err == nil {
+		for _, mx := range mxRecords {
+			mxIps, err := net.LookupIP(mx.Host)
+			if err != nil {
+				continue
+			}
+			for _, ip := range mxIps {
+				if ip.String() == clientIp {
+					return nil
+				}
+			}
+		}
+	}
+
+	return fmt.Errorf("invalid sender domain: %s", senderDomain)
+}
+func (s *SmtpSession) Rcpt(to string, opts *smtp.RcptOptions) error {
+	parts := strings.Split(to, "@")
+	if parts[1] != k.String("domain") {
+		return fmt.Errorf("invalid sender domain: %s", parts[1])
+	}
+
+	s.recipients = append(s.recipients, to)
+	return nil
+}
+
+func (s *SmtpSession) Data(r io.Reader) error {
+	data, err := io.ReadAll(r)
+	if err != nil {
+		return fmt.Errorf("failed to read data: %w", err)
+	}
+
+	msg, err := mail.ReadMessage(bytes.NewReader(data))
+	if err != nil {
+		return fmt.Errorf("failed to read message: %w", err)
+	}
+
+	from := msg.Header.Get("From")
+	if fromAddr, err := mail.ParseAddress(from); err != nil || fromAddr.Address != s.sender {
+		return fmt.Errorf("invalid sender: %s", s.sender)
+	}
+
+	toAddrs, err := msg.Header.AddressList("To")
+	if err != nil {
+		return fmt.Errorf("failed to parse To header: %w", err)
+	}
+
+	for _, recipient := range s.recipients {
+		if !slices.ContainsFunc(toAddrs, func(toAddr *mail.Address) bool {
+			return recipient == toAddr.Address
+		}) {
+			return fmt.Errorf("invalid recipient: %s", recipient)
+		}
+
+		parts := strings.Split(recipient, "@")
+		if parts[1] != k.String("domain") {
+			return fmt.Errorf("invalid recipient domain: %s", parts[1])
+		}
+
+		a, err := app.LoadApp(parts[0], k.String("dir"), k.String("domain"), slices.Contains(k.Strings("adminApps"), parts[0]))
+		if err != nil {
+			return fmt.Errorf("failed to load app: %w", err)
+		}
+
+		wk := worker.NewWorker(a)
+		wk.SendEmail(context.Background(), bytes.NewReader(data))
+	}
+
+	return nil
+}
+
+func (s *SmtpSession) Logout() error {
+	return nil
+}

docker-compose.yml

@@ -4,5 +4,6 @@ services:
     ports:
       - 7777:7777
       - 2222:2222
+      - 2525:2525
     volumes:
       - ./examples:/smallweb

examples/inbox/email.eml

@@ -1,5 +1,5 @@
 Subject: Ceci est un test
-From: [email protected]
+From: "Myself" <me@localhost>
 To: [email protected]
 Content-Type: text/plain; charset=utf-8
 

examples/inbox/run.sh

@@ -1,6 +1,6 @@
 #!/bin/sh
 
-curl smtp://localhost:2525 \
-  --mail-from '[email protected]' \
+curl -v smtp://localhost:2525 \
+  --mail-from 'me@localhost' \
   --mail-rcpt '[email protected]' \
   --upload-file email.eml

go.mod

@@ -23,15 +23,15 @@ require (
 require (
 	github.com/caddyserver/certmagic v0.21.4
 	github.com/carapace-sh/carapace v1.5.0
+	github.com/charmbracelet/keygen v0.5.1
 	github.com/charmbracelet/ssh v0.0.0-20241211182756-4fe22b0f1b7c
 	github.com/creack/pty v1.1.21
+	github.com/emersion/go-smtp v0.21.3
 	github.com/fsnotify/fsnotify v1.8.0
 	github.com/getsops/sops/v3 v3.9.1
 	github.com/google/shlex v0.0.0-20191202100458-e7afc7fbc510
-	github.com/google/uuid v1.6.0
 	github.com/knadh/koanf/providers/confmap v0.1.0
 	github.com/knadh/koanf/providers/posflag v0.1.0
-	github.com/mhale/smtpd v0.8.3
 	github.com/pkg/sftp v1.13.7
 	github.com/robfig/cron/v3 v3.0.1
 	golang.org/x/crypto v0.31.0
@@ -83,7 +83,6 @@ require (
 	github.com/caddyserver/zerossl v0.1.3 // indirect
 	github.com/carapace-sh/carapace-shlex v1.0.1 // indirect
 	github.com/cenkalti/backoff/v4 v4.3.0 // indirect
-	github.com/charmbracelet/keygen v0.5.1 // indirect
 	github.com/charmbracelet/lipgloss v0.13.0 // indirect
 	github.com/charmbracelet/x/ansi v0.2.3 // indirect
 	github.com/charmbracelet/x/conpty v0.1.0 // indirect
@@ -94,6 +93,7 @@ require (
 	github.com/cpuguy83/go-md2man/v2 v2.0.5 // indirect
 	github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc // indirect
 	github.com/dlclark/regexp2 v1.11.0 // indirect
+	github.com/emersion/go-sasl v0.0.0-20200509203442-7bfe0ed36a21 // indirect
 	github.com/fatih/color v1.17.0 // indirect
 	github.com/felixge/httpsnoop v1.0.4 // indirect
 	github.com/getsops/gopgagent v0.0.0-20240527072608-0c14999532fe // indirect
@@ -106,6 +106,7 @@ require (
 	github.com/golang/protobuf v1.5.4 // indirect
 	github.com/google/go-cmp v0.6.0 // indirect
 	github.com/google/s2a-go v0.1.8 // indirect
+	github.com/google/uuid v1.6.0 // indirect
 	github.com/googleapis/enterprise-certificate-proxy v0.3.4 // indirect
 	github.com/googleapis/gax-go/v2 v2.13.0 // indirect
 	github.com/gorilla/css v1.0.1 // indirect

go.sum

@@ -163,6 +163,10 @@ github.com/docker/go-connections v0.5.0 h1:USnMq7hx7gwdVZq1L49hLXaFtUdTADjXGp+uj
 github.com/docker/go-connections v0.5.0/go.mod h1:ov60Kzw0kKElRwhNs9UlUHAE/F9Fe6GLaXnqyDdmEXc=
 github.com/docker/go-units v0.5.0 h1:69rxXcBk27SvSaaxTtLh/8llcHD8vYHT7WSdRZ/jvr4=
 github.com/docker/go-units v0.5.0/go.mod h1:fgPhTUdO+D/Jk86RDLlptpiXQzgHJF7gydDDbaIK4Dk=
+github.com/emersion/go-sasl v0.0.0-20200509203442-7bfe0ed36a21 h1:OJyUGMJTzHTd1XQp98QTaHernxMYzRaOasRir9hUlFQ=
+github.com/emersion/go-sasl v0.0.0-20200509203442-7bfe0ed36a21/go.mod h1:iL2twTeMvZnrg54ZoPDNfJaJaqy0xIQFuBdrLsmspwQ=
+github.com/emersion/go-smtp v0.21.3 h1:7uVwagE8iPYE48WhNsng3RRpCUpFvNl39JGNSIyGVMY=
+github.com/emersion/go-smtp v0.21.3/go.mod h1:qm27SGYgoIPRot6ubfQ/GpiPy/g3PaZAVRxiO/sDUgQ=
 github.com/envoyproxy/go-control-plane v0.9.0/go.mod h1:YTl/9mNaCwkRvm6d1a2C3ymFceY/DCBVvsKhRF0iEA4=
 github.com/envoyproxy/go-control-plane v0.9.1-0.20191026205805-5f8ba28d4473/go.mod h1:YTl/9mNaCwkRvm6d1a2C3ymFceY/DCBVvsKhRF0iEA4=
 github.com/envoyproxy/go-control-plane v0.9.4/go.mod h1:6rpuAdCZL397s3pYoYcLgu1mIlRU8Am5FuJP05cCM98=
@@ -300,8 +304,6 @@ github.com/mattn/go-isatty v0.0.20/go.mod h1:W+V8PltTTMOvKvAeJH7IuucS94S2C6jfK/D
 github.com/mattn/go-runewidth v0.0.12/go.mod h1:RAqKPSqVFrSLVXbA8x7dzmKdmGzieGRCM46jaSJTDAk=
 github.com/mattn/go-runewidth v0.0.16 h1:E5ScNMtiwvlvB5paMFdw9p4kSQzbXFikJ5SQO6TULQc=
 github.com/mattn/go-runewidth v0.0.16/go.mod h1:Jdepj2loyihRzMpdS35Xk/zdY8IAYHsh153qUoGf23w=
-github.com/mhale/smtpd v0.8.3 h1:8j8YNXajksoSLZja3HdwvYVZPuJSqAxFsib3adzRRt8=
-github.com/mhale/smtpd v0.8.3/go.mod h1:MQl+y2hwIEQCXtNhe5+55n0GZOjSmeqORDIXbqUL3x4=
 github.com/mholt/acmez/v2 v2.0.3 h1:CgDBlEwg3QBp6s45tPQmFIBrkRIkBT4rW4orMM6p4sw=
 github.com/mholt/acmez/v2 v2.0.3/go.mod h1:pQ1ysaDeGrIMvJ9dfJMk5kJNkn7L2sb3UhyrX6Q91cw=
 github.com/microcosm-cc/bluemonday v1.0.27 h1:MpEUotklkwCSLeH+Qdx1VJgNqLlpY2KXwXFM08ygZfk=

worker/worker.go

@@ -508,7 +508,7 @@ func (me *Worker) Command(ctx context.Context, args ...string) (*exec.Cmd, error
 	return command, nil
 }
 
-func (me *Worker) SendEmail(ctx context.Context, message io.Reader) error {
+func (me *Worker) SendEmail(ctx context.Context, data io.Reader) error {
 	deno, err := DenoExecutable()
 	if err != nil {
 		return fmt.Errorf("could not find deno executable")
@@ -541,7 +541,7 @@ func (me *Worker) SendEmail(ctx context.Context, message io.Reader) error {
 
 	go func() {
 		defer stdin.Close()
-		io.Copy(stdin, message)
+		io.Copy(stdin, data)
 	}()
 
 	return command.Run()