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bug#40354: [PATCH] Fix Libravatar federation handling
From: |
Philip K. |
Subject: |
bug#40354: [PATCH] Fix Libravatar federation handling |
Date: |
Tue, 18 Aug 2020 20:53:37 +0200 |
Lars Ingebrigtsen <larsi@gnus.org> writes:
> Lars Ingebrigtsen <larsi@gnus.org> writes:
>
>> Philip K <philip@warpmail.net> writes:
>>
>>> Previous implementation didn't correctly handle the result of
>>> dns-query, and didn't implement the necessary record selection
>>> algorithm as specified on the wiki (https://wiki.libravatar.org/api/,
>>> "Federated servers").
>>>
>>> * lisp/image/gravatar.el (gravatar--service-libravatar): Fix
>>> libravatar image host resolver algorithm.
>>
>> Looks good to me, although this didn't apply either, since the code has
>> been rewritten to be asynchronous. Could you re-spin this patch, too,
>> and I'll get it applied...
>
> Philip, have you had time to look at this?
The patch below should implement the fixes from bug#40354. I found a
libravatar user here[0], and could test it by evaluating
(gravatar--service-libravatar "who@zerokspot.com" #'message)
or
(gravatar--service-libravatar "who@gnu.org" #'message)
as an example for a domain that doesn't use libravatar. Both work as
expected, and don't lag.
[0]: https://zerokspot.com/weblog/2020/05/26/avatars-without-gravatar/
--
Philip K.
>From 9b345b965cce8f79aa31b6a8989ff466c84b6798 Mon Sep 17 00:00:00 2001
From: Philip K <philipk@posteo.net>
Date: Tue, 18 Aug 2020 20:50:07 +0200
Subject: [PATCH] Fix Libravatar federation handling
Previous implementation didn't correctly handle the result of
dns-query, and didn't implement the necessary record selection
algorithm as specified on the wiki (https://wiki.libravatar.org/api/,
"Federated servers").
* lisp/image/gravatar.el (gravatar--service-libravatar): Implement
correct algorithm
---
lisp/image/gravatar.el | 49 ++++++++++++++++++++++++++++++++++++------
1 file changed, 42 insertions(+), 7 deletions(-)
diff --git a/lisp/image/gravatar.el b/lisp/image/gravatar.el
index e917033562..cca737656c 100644
--- a/lisp/image/gravatar.el
+++ b/lisp/image/gravatar.el
@@ -158,18 +158,53 @@ gravatar--service-libravatar
(setq func
(lambda (result)
(cond
- (result
- (funcall callback (format "%s://%s/avatar"
- (cdar records) result)))
- ((> (length records) 1)
- (pop records)
+ ((and result ;there is a result
+ (let* ((data (mapcar (lambda (record)
+ (dns-get 'data (cdr record)))
+ (dns-get 'answers result)))
+ (priorities (mapcar (lambda (r) (dns-get
'priority r))
+ data))
+ (max-priority (if priorities
+ (apply #'max priorities)
+ 0))
+ (sum 0) top)
+ ;; Attempt to find all records with the same maximal
+ ;; priority, and calculate the sum of their weights.
+ (dolist (ent data)
+ (when (= max-priority (dns-get 'priority ent))
+ (setq sum (+ sum (dns-get 'weight ent)))
+ (push ent top)))
+ ;; In case there is more than one maximal priority
+ ;; record, choose one at random, while taking the
+ ;; individual record weights into consideration.
+ (catch 'done
+ (dolist (ent top)
+ (when (and (or (= 0 sum)
+ (<= 0 (random sum) (dns-get
'weight ent)))
+ ;; Ensure that port and domain data are
+ ;; valid. In case non of the results
+ ;; were valid, `catch' will evaluate to
+ ;; nil, and the next cond clause will
be
+ ;; tested.
+ (<= 1 (dns-get 'port ent) 65535)
+ (string-match-p "\\`[-.0-9A-Za-z]+\\'"
+ (dns-get 'target ent)))
+ (funcall callback
+ (url-normalize-url (format
"%s://%s:%s/avatar"
+ (cdar
records)
+ (dns-get
'target ent)
+ (dns-get
'port ent))))
+ (throw 'done t))
+ (setq sum (- sum (dns-get 'weight ent))))))))
+ ((setq records (cdr records)) ;in case there are at least two
methods
(dns-query-asynchronous
(concat (caar records) "._tcp." domain)
func 'SRV))
- (t
+ (t ;fallback
(funcall callback "https://seccdn.libravatar.org/avatar")))))
(dns-query-asynchronous
- (concat (caar records) "._tcp." domain) func 'SRV)))))
+ (concat (caar records) "._tcp." domain)
+ func 'SRV t)))))
(defun gravatar-hash (mail-address)
"Return the Gravatar hash for MAIL-ADDRESS."
--
2.26.2