Mercurial > prosody-modules
view mod_inject_ecaps2/mod_inject_ecaps2.lua @ 4651:8231774f5bfd
mod_cloud_notify_encrypted: Ensure body substring remains valid UTF-8
The `body:sub()` call risks splitting the string in the middle of a
multi-byte UTF-8 sequence. This should have been caught by util.stanza
validation, but that would have caused some havoc, at the very least causing
the notification to not be sent.
There have been no reports of this happening. Likely because this module
isn't widely deployed among users with languages that use many longer UTF-8
sequences.
The util.encodings.utf8.valid() function is O(n) where only the last
sequence really needs to be checked, but it's in C and expected to be fast.
author | Kim Alvefur <zash@zash.se> |
---|---|
date | Sun, 22 Aug 2021 13:22:59 +0200 |
parents | ce946d9d982e |
children |
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module:depends("cache_c2s_caps"); local st = require "util.stanza"; local hashes = require "util.hashes"; local base64 = require "util.encodings".base64; local t_insert, t_sort, t_concat = table.insert, table.sort, table.concat; local algorithms = module:get_option_set("ecaps2_hashes", { "sha-256", "sha-512" }); -- TODO: Add all of the other hashes supported. local algorithm_map = { ["sha-256"] = hashes.sha256; ["sha-512"] = hashes.sha512; }; -- TODO: move that to util.caps maybe. local function calculate_hash(disco_info) local identities, features, extensions = {}, {}, {}; for _, tag in ipairs(disco_info) do if tag.name == "identity" then t_insert(identities, ((tag.attr.category or "").."\31".. (tag.attr.type or "").."\31".. (tag.attr["xml:lang"] or "").."\31".. (tag.attr.name or "").."\31\30")); elseif tag.name == "feature" then t_insert(features, (tag.attr.var or "").."\31"); elseif tag.name == "x" and tag.attr.xmlns == "jabber:x:data" then local form = {}; for _, field in ipairs(tag.tags) do if field.name == "field" and field.attr.xmlns == "jabber:x:data" and field.attr.var then local values = {}; for _, value in ipairs(field.tags) do if value.name == "value" and value.attr.xmlns == "jabber:x:data" then value = #value.tags == 0 and value:get_text(); if value then t_insert(values, value.."\31"); end end end t_sort(values); if #values > 0 then t_insert(form, field.attr.var.."\31"..t_concat(values, "\31").."\31\30"); else t_insert(form, field.attr.var.."\31\30"); end end end t_sort(form); form = t_concat(form, "\29").."\29"; t_insert(extensions, form); else return nil, "Unknown element in disco#info"; end end t_sort(identities); t_sort(features); t_sort(extensions); if #identities > 0 then identities = t_concat(identities, "\28").."\28"; else identities = "\28"; end if #features > 0 then features = t_concat(features).."\28"; else features = "\28"; end if #extensions > 0 then extensions = t_concat(extensions, "\28").."\28"; else extensions = "\28"; end return features..identities..extensions; end local function caps_handler(event) local origin = event.origin; if origin.presence == nil or origin.presence:get_child("c", "urn:xmpp:caps") then return; end local disco_info = origin.caps_cache; if disco_info == nil then return; end local extension_string, err = calculate_hash(disco_info); if extension_string == nil then module:log("warn", "Failed to calculate ecaps2 hash: %s", err) return; end local ecaps2 = st.stanza("c", { xmlns = "urn:xmpp:caps" }); for algo in algorithms do local func = algorithm_map[algo]; if func ~= nil then local hash = base64.encode(func(extension_string)); ecaps2:tag("hash", { xmlns = "urn:xmpp:hashes:2"; algo = algo }) :text(hash) :up(); end end module:log("debug", "Injected ecaps2 element in presence"); origin.presence:add_child(ecaps2); end module:hook("c2s-capabilities-changed", caps_handler);