From 1063e5b6eca536af07040ba929e872c3fc256444 Mon Sep 17 00:00:00 2001
From: Simon Ser <contact@emersion.fr>
Date: Thu, 18 Jan 2024 16:21:43 +0000
Subject: [PATCH] email: make PGP private key optional

Services other than meta.sr.ht don't really have a use for the
private PGP key.

Add a CanPGPSign method so that meta.sr.ht can emit a warning or
error when the PGP key is missing.
---
 email/worker.go | 61 ++++++++++++++++++++++++++++++-------------------
 1 file changed, 38 insertions(+), 23 deletions(-)

diff --git a/email/worker.go b/email/worker.go
index 0123fc0b985a08b01daf6d7f1cfcbec18e64dcc3..bb74a0ca183a5ac628111802e4d122287cc176b4 100644
--- a/email/worker.go
+++ b/email/worker.go
@@ -134,9 +134,13 @@ func EnqueueStd(ctx context.Context, header mail.Header,
 				strings.Join(rcpts, ", "), err.Error())
 		}
 
-		cleartext, err = prepareSigned(header, &buf, queue.entity)
-		if err != nil {
-			log.Fatalf("Signing mail failed: %v", err)
+		if queue.entity != nil {
+			cleartext, err = prepareSigned(header, &buf, queue.entity)
+			if err != nil {
+				log.Fatalf("Signing mail failed: %v", err)
+			}
+		} else {
+			cleartext = nopWriteCloser{&buf}
 		}
 	}
 	defer cleartext.Close()
@@ -157,6 +161,14 @@ func EnqueueStd(ctx context.Context, header mail.Header,
 	return queue.Enqueue(NewTask(&buf, rcpts))
 }
 
+type nopWriteCloser struct {
+	io.Writer
+}
+
+func (nopWriteCloser) Close() error {
+	return nil
+}
+
 type Queue struct {
 	*work.Queue
 	smtpFrom     *mail.Address
@@ -164,6 +176,11 @@ type Queue struct {
 	entity       *openpgp.Entity
 }
 
+// CanPGPSign checks whether emails sent via the queue are signed via OpenPGP.
+func (q *Queue) CanPGPSign() bool {
+	return q.entity != nil
+}
+
 // Creates a new email processing queue.
 func NewQueue(conf ini.File) *Queue {
 	smtpFrom, ok := conf.Get("mail", "smtp-from")
@@ -187,27 +204,25 @@ func NewQueue(conf ini.File) *Queue {
 		Address: ownerEmail,
 	}
 
-	privKeyPath, ok := conf.Get("mail", "pgp-privkey")
-	if !ok {
-		panic("Expected [mail]pgp-privkey in config")
-	}
-
-	privKeyFile, err := os.Open(privKeyPath)
-	if err != nil {
-		panic(fmt.Errorf("Failed to open [mail]pgp-privkey: %v", err))
-	}
-	defer privKeyFile.Close()
+	var entity *openpgp.Entity
+	if privKeyPath, ok := conf.Get("mail", "pgp-privkey"); ok {
+		privKeyFile, err := os.Open(privKeyPath)
+		if err != nil {
+			panic(fmt.Errorf("Failed to open [mail]pgp-privkey: %v", err))
+		}
+		defer privKeyFile.Close()
 
-	keyring, err := openpgp.ReadArmoredKeyRing(privKeyFile)
-	if err != nil {
-		panic(fmt.Errorf("Failed to read PGP key ring from [mail]pgp-privkey: %v", err))
-	}
-	if len(keyring) != 1 {
-		panic("Expected [mail]pgp-privkey to contain one key")
-	}
-	entity := keyring[0]
-	if entity.PrivateKey == nil || entity.PrivateKey.Encrypted {
-		panic("Failed to load [mail]pgp-privkey for email signature")
+		keyring, err := openpgp.ReadArmoredKeyRing(privKeyFile)
+		if err != nil {
+			panic(fmt.Errorf("Failed to read PGP key ring from [mail]pgp-privkey: %v", err))
+		}
+		if len(keyring) != 1 {
+			panic("Expected [mail]pgp-privkey to contain one key")
+		}
+		entity = keyring[0]
+		if entity.PrivateKey == nil || entity.PrivateKey.Encrypted {
+			panic("Failed to load [mail]pgp-privkey for email signature")
+		}
 	}
 
 	return &Queue{