fix: handling attachment when it is the only part of the message

REUSE.toml

@@ -96,7 +96,7 @@ SPDX-FileCopyrightText = "2022 Nextcloud GmbH and Nextcloud contributors"
 SPDX-License-Identifier = "AGPL-3.0-or-later"
 
 [[annotations]]
-path = ["src/tests/data/user@imap.localhost.chain.p12", "src/tests/data/user@imap.localhost.crt", "src/tests/data/user@imap.localhost.key", "src/tests/data/user@imap.localhost.p12", "tests/data/smime-certs/cn-only@imap.localhost.crt", "tests/data/smime-certs/cn-only@imap.localhost.key", "tests/data/smime-certs/imap.localhost.ca.crt", "tests/data/smime-certs/domain.tld.ca.crt", "tests/data/smime-certs/user@domain.tld.crt", "tests/data/smime-certs/user@domain.tld.key", "tests/data/smime-certs/user@imap.localhost.crt", "tests/data/smime-certs/user@imap.localhost.key", "tests/data/decrypted-message-body.txt", "tests/data/decrypted-signed-opaque-message-body.txt", "tests/data/encrypted-message.txt", "tests/data/encrypted-signed-opaque-message.txt", "tests/data/sieve-vacation-cleaned.sieve", "tests/data/sieve-vacation-off.sieve", "tests/data/sieve-vacation-on-no-end-date.sieve", "tests/data/sieve-vacation-on-no-tz.sieve", "tests/data/sieve-vacation-on-special-chars-message.sieve", "tests/data/sieve-vacation-on-special-chars-subject.sieve", "tests/data/sieve-vacation-on-subject-placeholder.sieve", "tests/data/sieve-vacation-on.sieve", "tests/data/signed-message.txt", "tests/data/signed-opaque-message.txt"]
+path = ["src/tests/data/user@imap.localhost.chain.p12", "src/tests/data/user@imap.localhost.crt", "src/tests/data/user@imap.localhost.key", "src/tests/data/user@imap.localhost.p12", "tests/data/smime-certs/cn-only@imap.localhost.crt", "tests/data/smime-certs/cn-only@imap.localhost.key", "tests/data/smime-certs/imap.localhost.ca.crt", "tests/data/smime-certs/domain.tld.ca.crt", "tests/data/smime-certs/user@domain.tld.crt", "tests/data/smime-certs/user@domain.tld.key", "tests/data/smime-certs/user@imap.localhost.crt", "tests/data/smime-certs/user@imap.localhost.key", "tests/data/decrypted-message-body.txt", "tests/data/decrypted-signed-opaque-message-body.txt", "tests/data/encrypted-message.txt", "tests/data/encrypted-signed-opaque-message.txt", "tests/data/nobody-message.txt", "tests/data/sieve-vacation-cleaned.sieve", "tests/data/sieve-vacation-off.sieve", "tests/data/sieve-vacation-on-no-end-date.sieve", "tests/data/sieve-vacation-on-no-tz.sieve", "tests/data/sieve-vacation-on-special-chars-message.sieve", "tests/data/sieve-vacation-on-special-chars-subject.sieve", "tests/data/sieve-vacation-on-subject-placeholder.sieve", "tests/data/sieve-vacation-on.sieve", "tests/data/signed-message.txt", "tests/data/signed-opaque-message.txt"]
 precedence = "aggregate"
 SPDX-FileCopyrightText = "2023 Nextcloud GmbH and Nextcloud contributors"
 SPDX-License-Identifier = "AGPL-3.0-or-later"

lib/IMAP/ImapMessageFetcher.php

@@ -217,6 +217,8 @@ public function fetchMessage(?Horde_Imap_Client_Data_Fetch $fetch = null): IMAPM
 				$bodyPartId = $structure->findBody();
 				if (!is_null($bodyPartId)) {
 					$this->getPart($structure[$bodyPartId], $bodyPartId, $isEncrypted || $isSigned);
+				} else {
+					$this->getPart($structure, '1', $isEncrypted || $isSigned);
 				}
 			}
 		} elseif (is_null($fetch)) {

tests/Integration/IMAP/ImapMessageFetcherIntegrationTest.php

@@ -231,4 +231,25 @@ public function testFetchMessageWithOpaqueSignedMessage(): void {
 		$this->assertTrue($message->isSigned());
 		$this->assertTrue($message->isSignatureValid());
 	}
+
+	public function testFetchMessageWithoutBody(): void {
+		$mimeMessage = file_get_contents(__DIR__ . '/../../data/nobody-message.txt');
+		$uid = $this->saveMimeMessage('INBOX', $mimeMessage);
+		$fetcher = $this->fetcherFactory
+			->build(
+				$uid,
+				'INBOX',
+				$this->getTestClient(),
+				$this->account->getUserId()
+			)
+			->withBody(true);
+
+		$message = $fetcher->fetchMessage();
+
+		$this->assertFalse($message->isEncrypted());
+		$this->assertCount(1, $message->attachments);
+		$attachment = $message->attachments[0];
+		$this->assertEquals('attach.zip', $attachment['fileName']);
+		$this->assertSame('application/zip', $attachment['mime']);
+	}
 }

tests/data/nobody-message.txt

@@ -0,0 +1,24 @@
+Return-Path: <debug@imap.localhost>
+Delivered-To: user@imap.localhost
+Received: from 0531f16fe281
+	by 0531f16fe281 (Dovecot) with LMTP id doHuJnh71GVlNwEAcWVang
+	for <user@imap.localhost>; Fri, 3 Jul 2026 00:35:01 +0000
+Received: from anton.vpn (unknown [172.17.0.1])
+	by 0531f16fe281 (Postfix) with ESMTP id 636C81E56
+	for <user@imap.localhost>; Fri, 3 Jul 2026 00:35:01 +0000 (UTC)
+From: debug@imap.localhost
+To: user@imap.localhost
+Cc:
+Subject: Just a file
+Message-ID: <20240220101506.Horde.UpbNuMMPVearQMy_n71Hu7U@anton.vpn>
+User-Agent: Horde Application Framework 5
+Date: Fri, 3 Jul 2026 00:35:01 +0000
+Content-Type: application/zip; name=attach.zip
+MIME-Version: 1.0
+Content-Disposition: attachment; filename=attach.zip
+Content-Transfer-Encoding: base64
+
+UEsDBAoAAAAAAC8E41wWNZYxBgAAAAYAAAAJABwAaGVsbG8udHh0VVQJAAM650ZqTedGanV4CwAB
+BOgDAAAE6AMAAEhlbGxvClBLAQIeAwoAAAAAAC8E41wWNZYxBgAAAAYAAAAJABgAAAAAAAEAAAC0
+gQAAAABoZWxsby50eHRVVAUAAzrnRmp1eAsAAQToAwAABOgDAABQSwUGAAAAAAEAAQBPAAAASQAA
+AAAA