So far we plan support for RFC822 and plan for RFC1522. with RFC1522 non ASCII
characters will be encoded.

@section Init/Destroy
The header should be initiliaze before any use.

@deftypefun int header_init (header_t *@var{hdr}, const char *@var{blurb}, size_t @var{len}, int @var{flag})
Initialize a @var{hdr} to a supported type.  If @var{blurb} is not NULL, it is
parsed. @var{Flag} can be set to RFC8222 or RFC1522 so far onlyr rfc822  is
supported.

@defmac MU_HDR_RFC822
Supports rfc 822, header style.
@end defmac

@defmac MU_HDR_RFC1522
Supports rfc 1522, encoding policy.
@end defmac

@end deftypefun

@deftypefun void header_destroy (header_t *@var{hdr})
The ressources allocate for @var{hdr} are freed.
@end deftypefun

@deftypefun int header_set_value (header_t @var{hdr}, const char *@var{fn}, const char *@var{fv}, size_t n, int @var{replace})
Set the field-name @var{fn} to field-value @var{fv} of size @var{n} in
@var{hdr}.  If @var{replace} is non-zero the initial value is replace, if zero
it is append.

Some basic macros is already provided for rfc822.

@defmac MU_HDR_UNIX_FROM
            "From "
@end defmac
@defmac MU_HDR_RETURN_PATH
          "Return-Path"
@end defmac
@defmac MU_HDR_RECEIVED
             "Received"
@end defmac
@defmac MU_HDR_DATE
                  "Date"
@end defmac
@defmac MU_HDR_FROM
                  "From"
@end defmac
@defmac MU_HDR_RESENT_FROM
           "Resent-From"
@end defmac
@defmac MU_HDR_SUBJECT
               "Subject"
@end defmac
@defmac MU_HDR_SENDER
                "Sender"
@end defmac
@defmac MU_HDR_RESENT_SENDER
         "Resent-SENDER"
@end defmac
@defmac MU_HDR_TO
                    "To"
@end defmac
@defmac MU_HDR_RESENT_TO
            "Resent-To"
@end defmac
@defmac MU_HDR_CC
                    "Cc"
@end defmac
@defmac MU_HDR_RESENT_CC
            "Resent-Cc"
@end defmac
@defmac MU_HDR_BCC
                   "Bcc"
@end defmac
@defmac MU_HDR_RESENT_BCC
            "Resent-Bcc"
@end defmac
@defmac MU_HDR_REPLY_TO
              "Reply-To"
@end defmac
@defmac MU_HDR_RESENT_REPLY_TO
       "Resent-Reply-To"
@end defmac
@defmac MU_HDR_MESSAGE_ID
            "Message-ID"
@end defmac
@defmac MU_HDR_RESENT_MESSAGE_ID
     "Resent-Message-ID"
@end defmac
@defmac MU_HDR_IN_REPLY_TO
           "In-Reply-To"
@end defmac
@defmac MU_HDR_ENCRYPTED
             "Encrypted"
@end defmac
@defmac MU_HDR_PRECEDENCE
            "Precedence"
@end defmac
@defmac MU_HDR_STATUS
                "Status"
@end defmac
@defmac MU_HDR_CONTENT_LENGTH
        "Content-Length"
@end defmac
@defmac MU_HDR_CONTENT_TYPE
          "Content-Type"
@end defmac
@defmac MU_HDR_MIME_VERSION
          "MIME-Version"
@end defmac

@end deftypefun

@deftypefun int header_get_value (header_t @var{hdr}, const char *fn, char *fv, size_t len, size_t *n)
Value of field-name @var{fn} is return in buffer @var{fv} of size @var{len}.
The number of bytes written is put in @var{n}.
@end deftypefun

@deftypefun int header_get_mvalue (header_t @var{hdr}, const char *fn, char **fv, size_t *n)
Value of field-name @var{fn} is return in allocated buffer @var{fn} from
@code{malloc(3)}. The number of bytes written is put in @var{n}.
@end deftypefun

@deftypefun int header_gvalue (const char *@var{blurb}, size_t @var{bl}, const char *@var{fn}, char *@var{fv}, size_t @var{len}, size_t *@var{n})
Field-name @var{fn} is extract form @var{blurb} of size @var{bl} and put in
buffer @var{fv} of size @var{len}.
The number of bytes written is put in @var{n}.
@end deftypefun

@deftypefun int header_gmvalue (const char *@var{blurb}, size_t @var{bl}, const char *@var{fn}, char **@var{fv}, size_t *@var{nv})
Field-name @var{fn} is extract form @var{blurb} of size @var{bl} and put in
@code{malloc(3)}ted buffer @var{fv}.  The number of bytes written is put in
@var{n}.
@end deftypefun

@section Headers Regex
@cindex Headers Regex

Using regular expression ?