From 9b345b965cce8f79aa31b6a8989ff466c84b6798 Mon Sep 17 00:00:00 2001 From: Philip K 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