Manageable UnexpectedEncodingException

src/Message/AbstractPart.php

@@ -277,6 +277,10 @@ final public function getPartNumber(): string
     final public function getDecodedContent(): string
     {
         if (null === $this->decodedContent) {
+            if (self::ENCODING_UNKNOWN === $this->getEncoding()) {
+                throw new UnexpectedEncodingException('Cannot decode a content with an uknown encoding');
+            }
+
             $content = $this->getContent();
             if (self::ENCODING_BASE64 === $this->getEncoding()) {
                 $content = \base64_decode($content);
@@ -322,11 +326,8 @@ private function parseStructure(\stdClass $structure)
     {
         $this->type = $this->typesMap[$structure->type] ?? self::TYPE_UNKNOWN;
 
-        if (!isset($this->encodingsMap[$structure->encoding])) {
-            throw new UnexpectedEncodingException(\sprintf('Cannot decode "%s"', $structure->encoding));
-        }
-
-        $this->encoding = $this->encodingsMap[$structure->encoding];
+        // In our context, \ENCOTHER is as useful as an uknown encoding
+        $this->encoding = $this->encodingsMap[$structure->encoding] ?? self::ENCODING_UNKNOWN;
         $this->subtype = $structure->subtype;
 
         foreach (['disposition', 'bytes', 'description'] as $optional) {

src/Message/PartInterface.php

@@ -25,6 +25,7 @@ interface PartInterface extends \RecursiveIterator
     const ENCODING_BINARY = 'binary';
     const ENCODING_BASE64 = 'base64';
     const ENCODING_QUOTED_PRINTABLE = 'quoted-printable';
+    const ENCODING_UNKNOWN = 'unknown';
 
     const SUBTYPE_PLAIN = 'PLAIN';
     const SUBTYPE_HTML = 'HTML';

tests/MessageTest.php

@@ -6,10 +6,12 @@
 
 use Ddeboer\Imap\Exception\InvalidDateHeaderException;
 use Ddeboer\Imap\Exception\MessageDoesNotExistException;
+use Ddeboer\Imap\Exception\UnexpectedEncodingException;
 use Ddeboer\Imap\Exception\UnsupportedCharsetException;
 use Ddeboer\Imap\Message;
 use Ddeboer\Imap\Message\EmailAddress;
 use Ddeboer\Imap\Message\Parameters;
+use Ddeboer\Imap\Message\PartInterface;
 use Ddeboer\Imap\Message\Transcoder;
 use Ddeboer\Imap\MessageIterator;
 use Ddeboer\Imap\Search;
@@ -837,6 +839,28 @@ public function testNoMessageId()
         $this->assertNull($message->getId());
     }
 
+    public function testUnknownEncodingIsManageable()
+    {
+        $this->mailbox->addMessage($this->getFixture('unknown_encoding'));
+
+        $message = $this->mailbox->getMessage(1);
+
+        $parts = [];
+        foreach ($message->getParts() as $part) {
+            $parts[$part->getSubtype()] = $part;
+        }
+
+        $this->assertArrayHasKey(PartInterface::SUBTYPE_PLAIN, $parts);
+
+        $plain = $parts[PartInterface::SUBTYPE_PLAIN];
+
+        $this->assertSame(PartInterface::ENCODING_UNKNOWN, $plain->getEncoding());
+
+        $this->expectException(UnexpectedEncodingException::class);
+
+        $plain->getDecodedContent();
+    }
+
     private function resetAttachmentCharset(Message $message)
     {
         // Mimic GMAIL behaviour that correctly doesn't report charset

tests/fixtures/unknown_encoding.eml

@@ -0,0 +1,24 @@
+From: [email protected]
+To: [email protected]
+Date: Wed, 27 Sep 2017 12:48:51 +0200
+Subject: test
+Content-Type: multipart/alternative;
+	boundary="----=_NextPart_000_0081_01D32C91.033E7020"
+
+This is a multipart message in MIME format.
+
+------=_NextPart_000_0081_01D32C91.033E7020
+Content-Type: text/plain;
+	charset=
+Content-Transfer-Encoding: foobar
+
+MyPlain
+
+------=_NextPart_000_0081_01D32C91.033E7020
+Content-Type: text/html;
+	charset=""
+Content-Transfer-Encoding: quoted-printable
+
+MyHtml
+------=_NextPart_000_0081_01D32C91.033E7020--
+