net/mail: ReadMessage fails with messages that have an empty body

[hbbio]

What version of Go are you using (go version)?

1.10

Does this issue reproduce with the latest release?

Yes

What operating system and processor architecture are you using (go env)?

Could do, but not relevant

What did you do?

Parsing emails from Apple Mail with net/mail.ReadMessage fails with EOF. Indeed some emails (typically: Calendar invites) have no body. This might violate the spec, but still is common.

What did you expect to see?

As described in #15632, ReadMessage should accept a missing body.

What did you see instead?

Returns error EOF.

[bradfitz]

Again, like in #15632, we need more information.

Where/how do you get such emails? How does this arise?

[hbbio]

Here is a sample message, this being the full message (some parts redacted). As I said, this is a calendar invitation sent from Exchange which contains strictly no body.

BEGIN:VCALENDAR
METHOD:PUBLISH
PRODID:Microsoft Exchange Server 2010
VERSION:2.0
BEGIN:VTIMEZONE
TZID:Romance Standard Time
BEGIN:STANDARD
DTSTART:16010101T030000
TZOFFSETFROM:+0200
TZOFFSETTO:+0100
RRULE:FREQ=YEARLY;INTERVAL=1;BYDAY=-1SU;BYMONTH=10
END:STANDARD
BEGIN:DAYLIGHT
DTSTART:16010101T020000
TZOFFSETFROM:+0100
TZOFFSETTO:+0200
RRULE:FREQ=YEARLY;INTERVAL=1;BYDAY=-1SU;BYMONTH=3
END:DAYLIGHT
END:VTIMEZONE
BEGIN:VEVENT
ORGANIZER;CN=Henri Binsztok:MAILTO:(redacted)
SUMMARY;LANGUAGE=en-US:(redacted)
DTSTART;TZID=Romance Standard Time:20161103T093000
DTEND;TZID=Romance Standard Time:20161103T100000
UID:040000008200E00074C5B7101A82E00800000000412CFA04FE25D201000000000000000
 01000000036A5936C5FB86A4394645DFA5DB4A769
CLASS:PUBLIC
PRIORITY:5
DTSTAMP:20161014T093334Z
TRANSP:OPAQUE
STATUS:CANCELLED
SEQUENCE:0
LOCATION;LANGUAGE=en-US:
X-MICROSOFT-CDO-APPT-SEQUENCE:0
X-MICROSOFT-CDO-OWNERAPPTID:2114613569
X-MICROSOFT-CDO-BUSYSTATUS:FREE
X-MICROSOFT-CDO-INTENDEDSTATUS:BUSY
X-MICROSOFT-CDO-ALLDAYEVENT:FALSE
X-MICROSOFT-CDO-IMPORTANCE:1
X-MICROSOFT-CDO-INSTTYPE:0
X-MICROSOFT-DISALLOW-COUNTER:FALSE
BEGIN:VALARM
DESCRIPTION:REMINDER
TRIGGER;RELATED=START:-PT15M
ACTION:DISPLAY
END:VALARM
END:VEVENT
END:VCALENDAR

Edit: I scanned all my mailboxes, and these calendar messages are the only instances where EOF happens.

[bradfitz]

That's not an email MIME message.