Tcl Library Source Code

Hello,

currently experienced, that an eMail had for one message part a Content-ID like "abc$def$ghi@jklmnop".

Using ::mime::getheader on that message part returned:

    % set header [::mime::getheader ::mime::3-2]
    Content-ID {{<002401c71848_6fba22d0$a500a8c0@dittc48ca0f6af>}}
    % dict get $header Content-ID
    {<002401c71848_6fba22d0$a500a8c0@dittc48ca0f6af>}
    % ::mime::getheader ::mime::3-2 Content-ID
    {<002401c71848_6fba22d0$a500a8c0@dittc48ca0f6af>}

I expected to get a once-braced value, but not a twice-braced value.

I used the mime package v1.5 from the tcllib 1.9 in tcl/tk 8.4.13 and 8.5a4.

IMHO this is a misbehaviour, a bug.

Thanks,

Martin Lemburg

As of [5006be5e6a3d2ccd] ::mime::getheader returns a dictionary of headers, where keys may be redundant. This eliminates the list behaviour described in this ticket. By the same token, when a key is provided, a list of matching headers is still returned. This variety of behaviours should be enough to satisfy both needs while remaining sufficiently convenient to use.

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There are many headers that are only supposed to appear once, and many that may appear multiple times. There's no easy way to provide a list of all headers that should only appear once and all headers that may appear multiple times. Now that you know why it happens, why not simply take [lindex ... 0] of any header that your code expects to appear only once? Or, alternately, check that the list length is indeed only 1, and provide an error message if you are given a malformed message?

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I do still think, that this is a bug!

The Content-Id inside a "header" of a message part must be a real identifier!
There is only one Content-Id per message part, or the message is mal formed!

So the Content-ID should not be a list.

I think from my own experience, that there is some addition quoting/bracing because of the "$" inside the Content-ID.
If this is needed during parsing the message part ... ok.
But returning the additionally braced value is ... not ok and unexpected, because of the intention of this value, the Content-ID.

Good morning from Berlin/Germany,

Marti

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I don't believe this is a bug. Headers are allowed to be repeated, such as for "Received" headers. Putting "Received" in a list and other headers not in a list would require the mime package and the user to know every possible header, and it would require everyone knowing that a header that appears only once might in other messages appear multiple times. If you expect only one instance of a header in your message, just access the zero'th element of the list returned.