util.jid: Fix special escaping of '\' per XEP-0106
From XEP-0106 §2. Requirements:
> in certain circumstances, the escaping character itself ("\") might
> also be escaped
Later in §4.2 Address Transformation Algorithm it is stated that the
backslash would only be escaped if it forms an escape sequence. Thus
'\foo' is unaltered but '\20' must be escaped into '\5c20'.
Thanks to lovetox and jonas’ for brining up.
--- a/util/jid.lua Fri Aug 28 18:43:37 2020 +0200
+++ b/util/jid.lua Fri Aug 28 18:44:02 2020 +0200
@@ -22,7 +22,11 @@
["@"] = "\\40"; ["\\"] = "\\5c";
};
local unescapes = {};
-for k,v in pairs(escapes) do unescapes[v] = k; end
+local backslash_escapes = {};
+for k,v in pairs(escapes) do
+ unescapes[v] = k;
+ backslash_escapes[v] = v:gsub("\\", escapes)
+end
local _ENV = nil;
-- luacheck: std none
@@ -107,7 +111,7 @@
return (select(3, split(jid)));
end
-local function escape(s) return s and (s:gsub(".", escapes)); end
+local function escape(s) return s and (s:gsub("\\%x%x", backslash_escapes):gsub("[\"&'/:<>@ ]", escapes)); end
local function unescape(s) return s and (s:gsub("\\%x%x", unescapes)); end
return {