Subject: bug#70312: [PATCH v2] Avoid unnecessary escaping in url-build-query-string

From: Philip Kaludercic <[email-masked]>
Date: Sun, 19 May 2024 11:18:47 +0000

Dagfinn Ilmari Mannsåker <[email-masked]> writes:

> Hi again,
>
> I realised I'd forgotten to add tests, and that made me realise that
> url-query-allowed-chars is not correct for this, since that also
> contains '=', '&', and ';'. So here's an updated patch, which creates a
> new url-query-key-value-allowed-chars constant, which is
> url-query-allowed-chars minus the aforementioned three chars, and adds
> tests covering that, for both keys and values.

This patch breaks a script I have that authenticates via HTTP.
Apparently it doesn't escape enough now:

(url-build-query-string '((var "\"$%&')+:;<>?@]^{|}")))
"var=%22$%%26')+:%3B%3C%3E?@%5D%5E%7B%7C%7D"

whereas it used to be:

(url-build-query-string '((var "\"$%&')+:;<>?@]^{|}")))
"var=%22%24%25%26%27%29%2B%3A%3B%3C%3E%3F%40%5D%5E%7B%7C%7D"

If it is true, that it just unnecessarily escapes too much (and this is
not a problem), then I'd suggest reverting the patch as the easiest
solution to avoid breakage in the long term.

>
> - ilmari
>
>>>From 89db0a1226d8d7cca1846e9c737d4a67c971ec75 Mon Sep 17 00:00:00 2001
> From: =?UTF-8?q?Dagfinn=20Ilmari=20Manns=C3=A5ker?= <[email-masked]>
> Date: Tue, 9 Apr 2024 15:02:45 +0100
> Subject: [PATCH v2] Avoid unnecessary escaping in url-build-query-string
>
> * lisp/url/url-util.el (url-build-query-string):
> Create a new url-query-key-value-allowed-chars constant and pass that to
> url-hexify-string to avoid unnecessarily escaping characters that don't
> need to be escaped in query string keys and values.
> * test/lisp/url/url-util-tests.el (url-util-tests):
> Add test cases.
> ---
>  lisp/url/url-util.el            | 12 +++++++++++-
>  test/lisp/url/url-util-tests.el |  6 +++++-
>  2 files changed, 16 insertions(+), 2 deletions(-)
>
> diff --git a/lisp/url/url-util.el b/lisp/url/url-util.el
> index 5f45b98c7a5..f063efe18a6 100644
> --- a/lisp/url/url-util.el
> +++ b/lisp/url/url-util.el
> @@ -268,7 +268,8 @@ url-build-query-string
>     (lambda (key-vals)
>       (let ((escaped
>              (mapcar (lambda (sym)
> -                      (url-hexify-string (format "%s" sym))) key-vals)))
> +                      (url-hexify-string (format "%s" sym) url-query-key-value-allowed-chars))
> +                    key-vals)))
>         (mapconcat (lambda (val)
>                      (let ((vprint (format "%s" val))
>                            (eprint (format "%s" (car escaped))))
> @@ -410,6 +411,15 @@ url-query-allowed-chars
>    "Allowed-character byte mask for the query segment of a URI.
>  These characters are specified in RFC 3986, Appendix A.")
>  
> +(defconst url-query-key-value-allowed-chars
> +  (let ((vec (copy-sequence url-query-allowed-chars)))
> +    (aset vec ?= nil)
> +    (aset vec ?& nil)
> +    (aset vec ?\; nil)
> +    vec)
> +  "Allowed-charcter byte mask for keys and values in the query segment of a URI.
> +url-query-allowed-chars minus '=', '&', and ';'.")
> +
>  ;;;###autoload
>  (defun url-encode-url (url)
>    "Return a properly URI-encoded version of URL.
> diff --git a/test/lisp/url/url-util-tests.el b/test/lisp/url/url-util-tests.el
> index 133aa0ffd88..c6246d69a2a 100644
> --- a/test/lisp/url/url-util-tests.el
> +++ b/test/lisp/url/url-util-tests.el
> @@ -32,7 +32,11 @@ url-util-tests
>             ("key1=val1;key2=val2;key3=val1;key3=val2;key4;key5"
>              ((key1 "val1") (key2 val2) (key3 val1 val2) ("key4") (key5 "")) t)
>             ("key1=val1;key2=val2;key3=val1;key3=val2;key4=;key5="
> -            ((key1 val1) (key2 val2) ("key3" val1 val2) (key4) (key5 "")) t t)))
> +            ((key1 val1) (key2 val2) ("key3" val1 val2) (key4) (key5 "")) t t)
> +           ("key1=val/slash;key2=val%3Bsemi;key3=val%26amp;key4=val%3Deq"
> +            ((key1 "val/slash") (key2 "val;semi") (key3 "val&amp") (key4 "val=eq")) t)
> +           ("key%3Deq=val1;key%3Bsemi=val2;key%26amp=val3"
> +            (("key=eq" val1) ("key;semi" val2) ("key&amp" val3)) t)))
>          test)
>      (while tests
>        (setq test (car tests)

-- 
	Philip Kaludercic on icterid