[plt-scheme] Mailto Not Working in Help Desk (see PR 6241)

The Help Desk has a neat feature that when it shows doc.txt file, it scans
them for ftp and http urls and e-mail addresses and displays them as links.
Unfortunately, the e-mail links don't work correctly - they prepend '///' on
the front of the e-mail address.  Unfortunately, because of the way Outlook
works - I'm sure it's a feature - it isn't easy (or possible?) to get rid of
this in the address line in Outlook 2003.  I came across it when I was
submitting my packages to PLaneT and tried to follow the link and it didn't
work.  (And I then klutzed up typing it and it took even longer.)

 

This bug has apparently been around for a while since Problem Report 6241
dated May 2, 2003 deals with it in Version 204 and it's still open.  The PR
is assigned to Robby Findler.

 

It turns out that the problem is in the way urls are parsed into an internal
format and then turned back into strings.  There is no special parser for
mailto: urls and for some reason the general url->string function for these
generic urls adds the three slashes.

 

The following fix to the url->string function in the url-unit.ss file in the
net collection corrects the problem, but needs to be verified.

 

      (define url->string

        (lambda (url)

          (let ((scheme (url-scheme url))

                (user (url-user url))

                (host (url-host url))

                (port (url-port url))

                (path (url-path url))

                (query (url-query url))

                (fragment (url-fragment url)))

            (cond

             ((and scheme (string=? scheme "file"))

              (string-append "file:" 

                       (url->file-path url)

                             (or (and (not fragment) "")

                                 (string-append "#" fragment))))

;;; added ---v

             ((and scheme (string=? scheme "mailto"))

              (string-append "mailto:"

                             (car path)))

;;; ---------^

             (else

              (let ((sa string-append))

                (sa (if scheme (sa scheme "://") "")

                    (if user (sa (uri-encode user) "@") "")

                    (if host host "")

                    (if port (sa ":" (number->string port)) "")

                                        ; There used to be a "/" here, but
that causes an

                                        ; extra leading slash -- wonder why
it ever worked!

                    (combine-path-strings path)

                    ;(if query (sa "?" (uri-encode query)) "")

                    (if (null? query) "" (sa "?"  (alist->form-urlencoded
query)))

                    (if fragment (sa "#" (uri-encode fragment)) ""))))))))

 

This fixes the particular problem with mailto: urls in the help desk.  I
can't see that it would break anything else.

 

This fix is based on how the parser actually parses mailto: urls - with
url-scheme = "mailto" and url-path = ("<the address>").  One could debate
that there should be code in the parser to handle mailto: urls, but there
isn't.

 

Doug

 

M. Douglas Williams, Ph.D.

Sr. Scientist

Science Applications International Corporation

4B Inverness Drive East, Suite 210

Englewood, CO  80112

office: (303) 217-4421

cell: (303) 229-0315

m.douglas.williams at saic.com <mailto:m.douglas.williams at saic.com> 

 

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