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
|
defmodule Irc.STS do
@moduledoc """
# STS Store.
When a connection encounters a STS policy, it signals it using `witness/4`. The store will consider the policy valid indefinitely as long as
any connection are still alive for that host/port pair. Once all connections or the system stops, the latest policy expiration date will be computed.
By default, the store is not persistent. If you wish to enable persistance, set the `:irc, :sts_cache_file` app environment.
"""
@ets __MODULE__.ETS
# tuple {{host,port}, tls_port, period, until | true, at}
@doc "Lookup a STS entry"
@spec lookup(host :: String.t(), port :: Integer.t()) :: {enabled :: boolean, port :: Integer.t()}
def lookup(host,port) do
with \
[{_, port, period, until}] <- :ets.lookup(@ets, {host,port}),
true <- verify_validity(period, until)
do
{true, port}
else
[] -> {false, port}
false ->
GenServer.cast(__MODULE__, {:expired, {host,port}})
{false, port}
end
end
@doc """
Signal a STS policy.
The STS cache will consider the policy as infinitely valid as long as the calling PID is alive,
or signal a new `witness/4`.
"""
def witness(host, port, sts_port, period) do
GenServer.call(__MODULE__, {:witness, host, port, sts_port, period, self()})
end
@doc """
Revoke a STS policy. This is the same as calling `witness/4` with sts_port = nil and period = nil.
"""
def revoke(host, port) do
GenServer.call(__MODULE__, {:witness, {host,port,nil,nil,self()}})
end
@doc "Returns all entries in the STS store"
def all() do
fold = fn(el, acc) -> [el | acc] end
:ets.foldl(fold, @ets, [])
end
def start_link() do
GenServer.start_link(__MODULE__, [], [name: __MODULE__])
end
def init(_) do
ets = :ets.new(@ets, [:named_table, :protected])
cache_file = Application.get_env(:irc, :sts_cache_file)
dets = if cache_file do
{:ok, dets} = :dets.open_file(cache_file)
true = :ets.from_dets(ets, dets)
end
{:ok, %{ets: ets, dets: dets, map: %{}}}
end
def handle_continue(nil, state) do
{:noreply, state}
end
def handle_continue(_, state = %{dets: nil}) do
{:noreply, state}
end
def handle_continue({:write, entry}, state = %{dets: dets}) do
:ok = :dets.insert(dets, entry)
:ok = :dets.sync(dets)
{:noreply, state}
end
def handle_continue({:remove, key}, state = %{dets: dets}) do
:ok = :dets.delete(dets, key)
:ok = :dets.sync(dets)
{:noreply, state}
end
# Duration 0 -- Policy is removed
def handle_call({:witness, host, port, _tls_port, period, pid}, from, state) when period in ["0", 0, nil] do
state = remove({host,port}, state)
{:reply, :ok, state, {:handle_continue, {:remove, {host,port}}}}
end
# Witnessed policy.
# As long as caller PID is alive, consider the policy always valid
def handle_call({:witness, host, port, tls_port, period, pid}, _, state) do
entry = {{host,port}, tls_port, period, true}
:ets.insert(@ets, entry)
mon = Process.monitor(pid)
state = %{state | map: Map.put(state.map, pid, {mon,{host,port}})}
{:reply, :ok, state, {:handle_continue, {:write, entry}}}
end
# Caller side encountered an expired policy, check and remove it.
def handle_cast({:expired, key}, state) do
{state, continue} = case :ets.lookup(@ets, key) do
[{_, _, period, until}] ->
if !verify_validity(period, until) do
{remove(key, state), {:remove, key}}
else
{state, nil}
end
[] -> {state, nil}
end
{:noreply, state, {:handle_continue, continue}}
end
# A connection disconnected
def handle_info({:DOWN, _, :process, pid, _}, state) do
key = Map.get(state.map, pid)
others = Enum.filter(state.map, fn({p, {_,k}}) -> k == key && p != pid end)
state = %{state | map: Map.delete(state.map, pid)}
if key && Enum.empty?(others) do
case :ets.lookup(@ets, key) do
[{key, tls_port, period, until}] ->
until = DateTime.utc_now() |> DateTime.add(period)
entry = {key, tls_port, period, until}
:ets.insert(@ets, entry)
{:noreply, state, {:handle_continue, {:write, entry}}}
[] ->
{:noreply, state}
end
else
{:noreply, state}
end
end
# Calculate expiration periods from time of shutdown.
def terminate(_, state) do
if state.dets do
fold = fn
({key, _tls_port, period, true}, acc) ->
until = DateTime.utc_now() |> DateTime.add(period)
[{key, until} | acc]
(_, acc) -> acc
end
for {key, until} <- :ets.foldl(fold, [], @ets) do
:ets.update_element(@ets, key, {4, until})
end
:ets.to_dets(@ets, state.dets)
:dets.close(state.dets)
end
:ok
end
# Remove an entry from ETS, demonitor related PIDs, and remove from map.
defp remove(key, state) do
:ets.delete(@ets, key)
pids = Enum.filter(state.map, fn({p, {mon,k}}) -> k == key end) |> Enum.map(fn({p, {mon,_}}) -> {p,mon} end)
for {_,mon} <- pids, do: Process.demonitor(mon, [:flush])
map = Enum.reduce(pids, state.map, fn({p,_}, map) -> Map.delete(map, p) end)
%{state | map: map}
end
defp verify_validity(_, true) do
true
end
defp verify_validity(_period, until) do
DateTime.utc_now() >= until
end
end
|
