aboutsummaryrefslogtreecommitdiffstats
path: root/plugins/mod_dialback.lua
blob: e47d63ed9cb38f6e4d2fd28f1d50649a3d7508b7 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
-- Prosody IM
-- Copyright (C) 2008-2010 Matthew Wild
-- Copyright (C) 2008-2010 Waqas Hussain
-- 
-- This project is MIT/X11 licensed. Please see the
-- COPYING file in the source package for more information.
--

local format = string.format;

local hosts = _G.hosts;
local s2s_make_authenticated = require "core.s2smanager".make_authenticated;

local log = module._log;

local st = require "util.stanza";
local sha256_hash = require "util.hashes".sha256;
local nameprep = require "util.encodings".stringprep.nameprep;

local xmlns_stream = "http://etherx.jabber.org/streams";

local dialback_requests = setmetatable({}, { __mode = 'v' });

function generate_dialback(id, to, from)
	return sha256_hash(id..to..from..hosts[from].dialback_secret, true);
end

function initiate_dialback(session)
	-- generate dialback key
	session.dialback_key = generate_dialback(session.streamid, session.to_host, session.from_host);
	session.sends2s(format("<db:result from='%s' to='%s'>%s</db:result>", session.from_host, session.to_host, session.dialback_key));
	session.log("info", "sent dialback key on outgoing s2s stream");
end

function verify_dialback(id, to, from, key)
	return key == generate_dialback(id, to, from);
end

module:hook("stanza/jabber:server:dialback:verify", function(event)
	local origin, stanza = event.origin, event.stanza;
	
	if origin.type == "s2sin_unauthed" or origin.type == "s2sin" then
		-- We are being asked to verify the key, to ensure it was generated by us
		origin.log("debug", "verifying that dialback key is ours...");
		local attr = stanza.attr;
		-- COMPAT: Grr, ejabberd breaks this one too?? it is black and white in XEP-220 example 34
		--if attr.from ~= origin.to_host then error("invalid-from"); end
		local type;
		if verify_dialback(attr.id, attr.from, attr.to, stanza[1]) then
			type = "valid"
		else
			type = "invalid"
			origin.log("warn", "Asked to verify a dialback key that was incorrect. An imposter is claiming to be %s?", attr.to);
		end
		origin.log("debug", "verified dialback key... it is %s", type);
		origin.sends2s(st.stanza("db:verify", { from = attr.to, to = attr.from, id = attr.id, type = type }):text(stanza[1]));
		return true;
	end
end);

module:hook("stanza/jabber:server:dialback:result", function(event)
	local origin, stanza = event.origin, event.stanza;
	
	if origin.type == "s2sin_unauthed" or origin.type == "s2sin" then
		-- he wants to be identified through dialback
		-- We need to check the key with the Authoritative server
		local attr = stanza.attr;
		local to, from = nameprep(attr.to), nameprep(attr.from);
		
		if not hosts[to] then
			-- Not a host that we serve
			origin.log("info", "%s tried to connect to %s, which we don't serve", from, to);
			origin:close("host-unknown");
			return true;
		elseif not from then
			origin:close("improper-addressing");
		end
		
		origin.hosts[from] = { dialback_key = stanza[1] };
		
		dialback_requests[from.."/"..origin.streamid] = origin;
		
		-- COMPAT: ejabberd, gmail and perhaps others do not always set 'to' and 'from'
		-- on streams. We fill in the session's to/from here instead.
		if not origin.from_host then
			origin.from_host = from;
		end
		if not origin.to_host then
			origin.to_host = nameprep(attr.to);
		end

		origin.log("debug", "asking %s if key %s belongs to them", from, stanza[1]);
		module:fire_event("route/remote", {
			from_host = to, to_host = from;
			stanza = st.stanza("db:verify", { from = to, to = from, id = origin.streamid }):text(stanza[1]);
		});
		return true;
	end
end);

module:hook("stanza/jabber:server:dialback:verify", function(event)
	local origin, stanza = event.origin, event.stanza;
	
	if origin.type == "s2sout_unauthed" or origin.type == "s2sout" then
		local attr = stanza.attr;
		local dialback_verifying = dialback_requests[attr.from.."/"..(attr.id or "")];
		module:log("debug", tostring(dialback_verifying).." "..attr.from.." "..origin.to_host);
		if dialback_verifying and attr.from == origin.to_host then
			local valid;
			if attr.type == "valid" then
				s2s_make_authenticated(dialback_verifying, attr.from);
				valid = "valid";
			else
				-- Warn the original connection that is was not verified successfully
				log("warn", "authoritative server for "..(attr.from or "(unknown)").." denied the key");
				valid = "invalid";
			end
			if not dialback_verifying.sends2s then
				log("warn", "Incoming s2s session %s was closed in the meantime, so we can't notify it of the db result", tostring(dialback_verifying):match("%w+$"));
			else
				dialback_verifying.sends2s(
						st.stanza("db:result", { from = attr.to, to = attr.from, id = attr.id, type = valid })
								:text(dialback_verifying.hosts[attr.from].dialback_key));
			end
			dialback_requests[attr.from.."/"..(attr.id or "")] = nil;
		end
		return true;
	end
end);

module:hook("stanza/jabber:server:dialback:result", function(event)
	local origin, stanza = event.origin, event.stanza;
	
	if origin.type == "s2sout_unauthed" or origin.type == "s2sout" then
		-- Remote server is telling us whether we passed dialback
		
		local attr = stanza.attr;
		if not hosts[attr.to] then
			origin:close("host-unknown");
			return true;
		elseif hosts[attr.to].s2sout[attr.from] ~= origin then
			-- This isn't right
			origin:close("invalid-id");
			return true;
		end
		if stanza.attr.type == "valid" then
			s2s_make_authenticated(origin, attr.from);
		else
			origin:close("not-authorized", "dialback authentication failed");
		end
		return true;
	end
end);

module:hook_stanza("urn:ietf:params:xml:ns:xmpp-sasl", "failure", function (origin, stanza)
	if origin.external_auth == "failed" then
		module:log("debug", "SASL EXTERNAL failed, falling back to dialback");
		initiate_dialback(origin);
		return true;
	end
end, 100);

module:hook_stanza(xmlns_stream, "features", function (origin, stanza)
	if not origin.external_auth or origin.external_auth == "failed" then
		module:log("debug", "Initiating dialback...");
		initiate_dialback(origin);
		return true;
	end
end, 100);

module:hook("s2s-authenticate-legacy", function (event)
	module:log("debug", "Initiating dialback...");
	initiate_dialback(event.origin);
	return true;
end, 100);

-- Offer dialback to incoming hosts
module:hook("s2s-stream-features", function (data)
	data.features:tag("dialback", { xmlns='urn:xmpp:features:dialback' }):up();
end);