Part of RFC 822 ignored by email module

[Martin Gregorie]

On Thu, 20 Jan 2011 12:55:44 -0500, Bob Kline wrote:

> On 1/20/2011 12:23 PM, Carl Banks wrote:
>> On Jan 20, 7:08 am, Bob Kline<bkl... at rksystems.com>  wrote:
>>> I just noticed that the following passage in RFC 822:
>>>
>>>           The process of moving  from  this  folded   multiple-line
>>>           representation  of a header field to its single line
>>>           represen- tation is called "unfolding".  Unfolding  is 
>>>           accomplished  by regarding   CRLF   immediately  followed 
>>>           by  a  LWSP-char  as equivalent to the LWSP-char.
>>>
>>> is not being honored by the email module.  The following two
>>> invocations of message_from_string() should return the same value, but
>>> that's not what happens:
>>>
>>>   >>>  import email
>>>   >>>  email.message_from_string("Subject: blah").get('SUBJECT')
>>> 'blah'
>>>   >>>  email.message_from_string("Subject:\n blah").get('SUBJECT')
>>> ' blah'
>>>
>>> Note the space in front of the second value returned, but missing from
>>> the first.  Can someone convince me that this is not a bug?
>> That's correct, according to my reading of RFC 822 (I doubt it's
>> changed so I didn't bother to look up what the latest RFC on that
>> subject is.)
>>
>> The RFC says that in a folded line the whitespace on the following line
>> is considered a part of the line.
> 
> Thanks for responding.  I think your interpretation of the RFC is the
> same is mine.  What I'm saying is that by not returning the same value
> in the two cases above the module is not "regarding CRLF immediately
> followed by a LWSP-char as equivalent to the LWSP-char."
>
That's only a problem if your code cares about the composition of the 
whitespace and this, IMO is incorrect behaviour. When the separator 
between syntactic elements in a header is 'whitespace' it should not 
matter what combination of newlines, tabs and spaces make up the 
whitespace element. 


-- 
martin@   | Martin Gregorie
gregorie. | Essex, UK
org       |