Fix token quoting with UTF-8 attributes

References #1191

CHANGELOG.rdoc

@@ -12,6 +12,7 @@ Performance:
 
 Bugs:
 * Fix transfer encoding when message encoding is blank. (jakubonty, saks)
+* Fix UTF-8 attachment filename quoting. (ahorek)
 
 
 == Version 2.7.0 (2017-10-31)

lib/mail/utilities.rb

@@ -45,7 +45,17 @@ def token_safe?( str )
     # If the string supplied has TOKEN unsafe characters in it, will return the string quoted
     # in double quotes, otherwise returns the string unmodified
     def quote_token( str )
-      token_safe?( str ) ? str : dquote(str)
+      if str.respond_to?(:force_encoding)
+        original_encoding = str.encoding
+        ascii_str = str.dup.force_encoding('ASCII-8BIT')
+        if token_safe?( ascii_str )
+          str
+        else
+          dquote(ascii_str).force_encoding(original_encoding)
+        end
+      else
+        token_safe?( str ) ? str : dquote(str)
+      end
     end
 
     # Wraps supplied string in double quotes and applies \-escaping as necessary,

spec/fixtures/emails/attachment_emails/attachment_nonascii_filename.eml

@@ -0,0 +1,28 @@
+Mime-Version: 1.0 (Apple Message framework v730)
+Content-Type: multipart/mixed; boundary=Apple-Mail-13-196941151
+Message-Id: <9169D984-4E0B-45EF-82D4-8F5E53AD7012@example.com>
+From: foo@example.com
+Subject: testing
+Date: Mon, 6 Jun 2005 22:21:22 +0200
+To: blah@example.com
+
+
+--Apple-Mail-13-196941151
+Content-Transfer-Encoding: quoted-printable
+Content-Type: text/plain;
+	charset=ISO-8859-1;
+	delsp=yes;
+	format=flowed
+
+This is the first part.
+
+--Apple-Mail-13-196941151
+Content-Type: text/plain; name=ciële.txt
+Content-Transfer-Encoding: 7bit
+Content-Disposition: attachment;
+	filename=ciële.txt
+
+Hi there.
+
+--Apple-Mail-13-196941151--
+

spec/mail/attachments_list_spec.rb

@@ -266,6 +266,12 @@ def check_decoded(actual, expected)
       expect(mail.attachments.first.filename).to eq "This is a test.txt"
     end
 
+    it "should decode an attachment without ascii compatible filename" do
+      mail = read_fixture('emails/attachment_emails/attachment_nonascii_filename.eml')
+      expect(mail.attachments.length).to eq 1
+      expect(mail.attachments.first.filename).to eq "ciële.txt"
+    end
+
     it "should find attachments inside parts with content-type message/rfc822" do
       mail = read_fixture('emails/attachment_emails/attachment_message_rfc822.eml')
       expect(mail.attachments.length).to eq 1