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
|
-module(munge).
-include("rep_literals.hrl").
-export([v1_handshake/2, v2_handshake/2, v3_handshake/2]).
-export([versions/1,real_to_spoofed/2, maybe_spoofed_to_real/2]).
versions(B) ->
Host = lists:takewhile(fun (X) -> X /= 0 end, binary_to_list(B)),
Skip = length(Host) + 1,
case B of
%%
%% version negotiation proposal
%%
<<_H:Skip/binary, Vmin:32/big, Vmax:32/big,
_Pad/binary>> ->
{Host, [Vmin, Vmax]};
%%
%% version confirmation
%%
<<_H:Skip/binary, V:32/big, _Pad/binary>> ->
{Host, V};
%%
%% legacy V1 handshake, with no extra version info
%%
_ ->
Host
end.
%%% Map might be Me (a tuple) or Config (a list of tuples)
%%%
v1_handshake(Msg, Map) ->
{?HANDSHAKE, ControlLength, RecLength, Control, Rec} = Msg,
<<Version:32/native, Port:16/native, _:16, Prio:32/big>> = Control,
NewPort = real_to_spoofed(Port, Map),
NewControl = <<Version:32/native, NewPort:16/native, 0:16, Prio:32/big>>,
NewMsg = {?HANDSHAKE, ControlLength, RecLength, NewControl, Rec},
{Port, NewMsg}.
v2_handshake(Msg, Map) ->
{?HANDSHAKE, ControlLength, RecLength, Control, Rec} = Msg,
<<Port:16/big, Prio:32/big>> = Control,
NewPort = real_to_spoofed(Port, Map),
NewControl = <<NewPort:16/big, Prio:32/big>>,
NewMsg = {?HANDSHAKE, ControlLength, RecLength, NewControl, Rec},
{Port, NewMsg}.
v3_handshake(Msg, Map) ->
{?HANDSHAKE, ControlLength, RecLength, Control, Rec} = Msg,
<<Port:16/big, Prio:32/big, Flags:32/big>> = Control,
NewPort = real_to_spoofed(Port, Map),
NewControl = <<NewPort:16/big, Prio:32/big, Flags:32/big>>,
NewMsg = {?HANDSHAKE, ControlLength, RecLength, NewControl, Rec},
{Port, NewMsg}.
%%% rcv handshake: real_to_spoofed(Config)
%%% send handshake: real_to_spoofed(Me)
%%%
%%% rcv NEWCLIENT: real_to_spoofed(Him)
%%% send NEWCLIENT: real_to_spoofed(Me)
%%%
%%% rcv NEWSITE: maybe_spoofed_to_real(Me)
%%% snd NEWSITE: maybe_spoofed_to_real(Him)
maybe_spoofed_to_real(Spoofed, {Spoofed,Real}) ->
Real;
maybe_spoofed_to_real(X, _) ->
X.
real_to_spoofed(Real, {Spoofed, Real}) ->
Spoofed;
real_to_spoofed(Real, Config) when is_list(Config) ->
{value, {Spoofed, _Real}} = lists:keysearch(Real, 2, Config),
Spoofed.
|
