header_get_value() field concat bug - anybody relying on this?

[Sam Roberts]

Bon soir,

In the process of getting the smtp mailer_t working (not leaking
bcc values, among other things) I've run into a problem Alain and
I discussed a long while back.

If multiple fields with a given value exist in a message
header, header_get_value() concatenates all the values and
returns them. This is never right.

RFC822 says:

  This specification permits multiple  occurrences  of  most
  fields.   Except  as  noted,  their  interpretation is not
  specified here, and their use is discouraged.

A few fields, such as received:, do have defined meanings for
multiple occurences, but are not parseable when all concatenated
together.

Multiple to: fields are arguably meaningless, so possibly a bug in the
message writer. However, like most (all?) structured fields, concatenating
two fields results in syntactically invalid fields:

to: address@hidden
to: address@hidden

header_get_value() gives me:

"address@hidden address@hidden"

This is an invalid address list.

Possible fixes:

1 - return the first field

  If you want fields like Received: you will be using
  header_get_field_value() looking at each one.

2 - add an index to header_get_value()
  
  so you ask for the 1st "received" field, or the 2nd, etc.

  this would have the nice side effect of allowing the replacement of
  header_get_value() and header_get_field_value() with a single function:

  header_get_value(header_t,
      const char *name, size_t index,
      char *value, size_t insz, size_t* outsz)

  a name of 0 could mean "any name", identical to the current
  header_get_field_value().

3 - make header_get_value() return an array of pointers to the values

===

I want to do 1 now, and 2 when I have the time (there are other things
to fix first).

Before I commit it, is imap, or something, relying on this odd
concatenation side-effect?

Salut,
Sam

-- 
Sam Roberts <address@hidden> (Vivez sans temps mort!)