Forbid logins on the SMTP-STARTTLS port

Also, introduce the outline of a framework to handle message sending
differently to message receipt.

internal/smtp/receiver.go

@@ -0,0 +1,20 @@
+package smtp
+
+import (
+	"fmt"
+	"io"
+)
+
+type Receiver struct{}
+
+func (r *Receiver) Name() string {
+	return "smtp-starttls"
+}
+
+// It seems odd to have a Receiver called Send, but what we're looking for is an
+// attempt from an arbitrary source to send an email to known accounts.
+//
+// We might want to clean this interface
+func (r *Receiver) Send(from string, to []string, reader io.Reader) error {
+	return fmt.Errorf("Not yet implemented")
+}

internal/smtp/sender.go

@@ -0,0 +1,21 @@
+package smtp
+
+import (
+	"fmt"
+	"io"
+)
+
+type Sender struct{}
+
+func (s *Sender) Name() string {
+	return "submission-starttls"
+}
+
+// We're looking for the email to be from a logged-in account, to anywhere
+// on the internet - including locally!
+//
+// Should we handle local delivery differently to remote delivery, or connect
+// to ourselves, i.e., from submission, to smtp?
+func (s *Sender) Send(from string, to []string, reader io.Reader) error {
+	return fmt.Errorf("Not yet implemented")
+}

internal/smtp/server.go

@@ -29,10 +29,11 @@ func NewServer(cancel context.CancelFunc, datastore store.Interface, submission
 	out.server.TLSConfig = datastore.TLSConfig()
 
 	if submission {
-		out.name = "submission"
+		out.handler = &Sender{}
 		out.server.Addr = ":587"
+		out.allowLogin = true // Only allow login on submission ports
 	} else {
-		out.name = "SMTP"
+		out.handler = &Receiver{}
 		out.server.Addr = ":25"
 	}
 
@@ -40,10 +41,12 @@ func NewServer(cancel context.CancelFunc, datastore store.Interface, submission
 }
 
 type concrete struct {
-	name   string
+	name       string
-	cancel context.CancelFunc
+	cancel     context.CancelFunc
-	store  store.Interface
+	store      store.Interface
-	server *smtp.Server
+	server     *smtp.Server
+	handler    Handler
+	allowLogin bool
 
 	// Session IDs
 	sid uint64
@@ -61,6 +64,10 @@ func (c *concrete) Run() {
 
 // backend implementation for go-smtp
 func (c *concrete) Login(user, pass string) (smtp.User, error) {
+	if !c.allowLogin {
+		return nil, fmt.Errorf("Login is disabled")
+	}
+
 	account, err := c.store.FindAccountWithPassword(user, pass)
 	if err != nil {
 		// Lo the real error, but don't show it to the end user
@@ -69,9 +76,9 @@ func (c *concrete) Login(user, pass string) (smtp.User, error) {
 	}
 
 	session := &Session{
-		ID:          atomic.AddUint64(&c.sid, uint64(1)),
+		ID:      atomic.AddUint64(&c.sid, uint64(1)),
-		Account:     account,
+		Account: account,
-		ServiceName: c.name,
+		Handler: c.handler,
 	}
 
 	log.Printf("Beginning %s session %d for %s", c.name, session.ID, user)

internal/smtp/session.go

@@ -1,7 +1,7 @@
 package smtp
 
 import (
-	"fmt"
+	"bytes"
 	"io"
 	"io/ioutil"
 	"log"
@@ -9,26 +9,33 @@ import (
 	"ur.gs/crockery/internal/store"
 )
 
+type Handler interface {
+	Name() string
+	Send(from string, to []string, r io.Reader) error
+}
+
 // type Session implements the User interface for emersion/go-smtp
 type Session struct {
-	ID          uint64
+	ID      uint64
-	Account     *store.Account
+	Account *store.Account
-	ServiceName string
+	Handler Handler
 }
 
 func (s *Session) Send(from string, to []string, r io.Reader) error {
+	// FIXME: TODO: don't keep this lot forever, it's for debugging purposes
 	data, err := ioutil.ReadAll(r)
 	if err != nil {
 		return err
 	}
 
-	log.Printf("%s session %d for %s: from=%s, to=%s, r=<<EOF\n%s\nEOF", s.ServiceName, s.ID, s.Account.Username, from, to, string(data))
+	log.Printf("%s session %d for %s: from=%s, to=%s, r=<<EOF\n%s\nEOF", s.Handler.Name(), s.ID, s.Account.Username, from, to, string(data))
 
-	return fmt.Errorf("Not yet implemented")
+	memR := bytes.NewReader(data)
+	return s.Handler.Send(from, to, memR)
 }
 
 func (s *Session) Logout() error {
-	log.Printf("Ending %s session %d for %s", s.ServiceName, s.ID, s.Account.Username)
+	log.Printf("Ending %s session %d for %s", s.Handler.Name(), s.ID, s.Account.Username)
 
 	return nil
 }