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
|
local adns = require "net.adns";
local inet_pton = require "util.net".pton;
local inet_ntop = require "util.net".ntop;
local idna_to_ascii = require "util.encodings".idna.to_ascii;
local promise = require "util.promise";
local t_move = require "util.table".move;
local methods = {};
local resolver_mt = { __index = methods };
-- FIXME RFC 6724
local function do_dns_lookup(self, dns_resolver, record_type, name, allow_insecure)
return promise.new(function (resolve, reject)
local ipv = (record_type == "A" and "4") or (record_type == "AAAA" and "6") or nil;
if ipv and self.extra["use_ipv"..ipv] == false then
return reject(("IPv%s disabled - %s lookup skipped"):format(ipv, record_type));
elseif record_type == "TLSA" and self.extra.use_dane ~= true then
return reject("DANE disabled - TLSA lookup skipped");
end
dns_resolver:lookup(function (answer, err)
if not answer then
return reject(err);
elseif answer.bogus then
return reject(("Validation error in %s lookup"):format(record_type));
elseif not (answer.secure or allow_insecure) then
return reject(("Insecure response in %s lookup"):format(record_type));
elseif answer.status and #answer == 0 then
return reject(("%s in %s lookup"):format(answer.status, record_type));
end
local targets = { secure = answer.secure };
for _, record in ipairs(answer) do
if ipv then
table.insert(targets, { self.conn_type..ipv, record[record_type:lower()], self.port, self.extra });
else
table.insert(targets, record[record_type:lower()]);
end
end
return resolve(targets);
end, name, record_type, "IN");
end);
end
local function merge_targets(ipv4_targets, ipv6_targets)
local result = { secure = ipv4_targets.secure and ipv6_targets.secure };
local common_length = math.min(#ipv4_targets, #ipv6_targets);
for i = 1, common_length do
table.insert(result, ipv6_targets[i]);
table.insert(result, ipv4_targets[i]);
end
if common_length < #ipv4_targets then
t_move(ipv4_targets, common_length+1, #ipv4_targets, common_length+1, result);
elseif common_length < #ipv6_targets then
t_move(ipv6_targets, common_length+1, #ipv6_targets, common_length+1, result);
end
return result;
end
-- Find the next target to connect to, and
-- pass it to cb()
function methods:next(cb)
if self.targets then
if #self.targets == 0 then
cb(nil);
return;
end
local next_target = table.remove(self.targets, 1);
cb(next_target[1], next_target[2], next_target[3], next_target[4], not not self.targets[1]);
return;
end
if not self.hostname then
self.last_error = "hostname failed IDNA";
cb(nil);
return;
end
-- Resolve DNS to target list
local dns_resolver = adns.resolver();
local dns_lookups = {
ipv4 = do_dns_lookup(self, dns_resolver, "A", self.hostname, true);
ipv6 = do_dns_lookup(self, dns_resolver, "AAAA", self.hostname, true);
tlsa = do_dns_lookup(self, dns_resolver, "TLSA", ("_%d._%s.%s"):format(self.port, self.conn_type, self.hostname));
};
promise.all_settled(dns_lookups):next(function (dns_results)
-- Combine targets, assign to self.targets, self:next(cb)
local have_ipv4 = dns_results.ipv4.status == "fulfilled";
local have_ipv6 = dns_results.ipv6.status == "fulfilled";
if have_ipv4 and have_ipv6 then
self.targets = merge_targets(dns_results.ipv4.value, dns_results.ipv6.value);
elseif have_ipv4 then
self.targets = dns_results.ipv4.value;
elseif have_ipv6 then
self.targets = dns_results.ipv6.value;
else
self.targets = {};
end
if self.extra and self.extra.use_dane then
if self.targets.secure and dns_results.tlsa.status == "fulfilled" then
self.extra.tlsa = dns_results.tlsa.value;
self.extra.dane_hostname = self.hostname;
else
self.extra.tlsa = nil;
self.extra.dane_hostname = nil;
end
elseif self.extra and self.extra.srv_secure then
self.extra.secure_hostname = self.hostname;
end
self:next(cb);
end):catch(function (err)
self.last_error = err;
self.targets = {};
end);
end
local function new(hostname, port, conn_type, extra)
local ascii_host = idna_to_ascii(hostname);
local targets = nil;
conn_type = conn_type or "tcp";
local is_ip = inet_pton(hostname);
if not is_ip and hostname:sub(1,1) == '[' then
is_ip = inet_pton(hostname:sub(2,-2));
end
if is_ip then
hostname = inet_ntop(is_ip);
if #is_ip == 16 then
targets = { { conn_type.."6", hostname, port, extra } };
elseif #is_ip == 4 then
targets = { { conn_type.."4", hostname, port, extra } };
end
end
return setmetatable({
hostname = ascii_host;
port = port;
conn_type = conn_type;
extra = extra or {};
targets = targets;
}, resolver_mt);
end
return {
new = new;
};
|
