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Add support for user specified forwarding
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Preliminary (untested): users can specify the destination IP/port for
the tunnel in the domain name.
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@msantos
msantos committed Jul 16, 2010
1 parent cb4d1be commit d98cad3
Showing 1 changed file with 99 additions and 12 deletions.
111 changes: 99 additions & 12 deletions src/seds.erl
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Original file line number Diff line number Diff line change
Expand Up @@ -42,6 +42,9 @@
terminate/2, code_change/3]).

-record(state, {
acf = false, % allow client forwarding
acl = [], % forward IP blacklist

f, % forwarders map
s, % socket
d = [], % domains
Expand Down Expand Up @@ -96,12 +99,11 @@ handle_cast(_Msg, State) ->

% DNS request from client
handle_info({udp, Socket, IP, Port, Data}, #state{
s = Socket,
d = Domains
s = Socket
} = State) ->
ok = inet:setopts(Socket, [{active, once}]),

case decode(Data, Domains) of
case decode(Data, State) of
false ->
{noreply, State};
{#dns_rec{} = Rec, #seds{} = Query} ->
Expand Down Expand Up @@ -172,13 +174,54 @@ session(#seds{
end,
{lists:nth(F, Map), Id}.

forward({_IP, _Port} = Forward) ->
{forward, Forward};
forward(Id) when is_integer(Id) ->
<<_Opt:8, Forward:8, SessionId:16>> = <<Id:32>>,
{{session, Forward}, SessionId}.


% mfz.wiztb.onsgmcq.40966-0.id-372571.u.192.168.100.101-2222.x.example.com
% B64._Nonce-Sum.id-SessionId.u.IP1.IP2.IP3.IP4-Port.x.Domain
decode({domain, {a, [Base64Nonce, Sum, "id", SessionId, "u",
IP1, IP2, IP3, IP4, Port, "x"|Domain]}},
#state{d = Domains, acf = true, acl = ACL}) ->
true = check_dn(Domain, Domains),
true = check_acl({IP1,IP2,IP3,IP4}, ACL),

B64 = string:tokens(Base64Nonce, "."),
Forward = forward({{IP1,IP2,IP3,IP4},Port}),

#seds{
type = up,
forward = Forward,
id = SessionId,
data = lists:flatten(lists:sublist(B64, length(B64)-1)),
sum = list_to_integer(Sum),
domain = Domain
};
decode({domain, {a, [Base64Nonce, Sum, "id", SessionId, "u",
IP1, IP2, IP3, IP4, "x"|Domain]}},
#state{d = Domains, acf = true, acl = ACL}) ->
true = check_dn(Domain, Domains),
true = check_acl({IP1,IP2,IP3,IP4}, ACL),

B64 = string:tokens(Base64Nonce, "."),
Forward = forward({{IP1,IP2,IP3,IP4}, 22}),

#seds{
type = up,
forward = Forward,
id = SessionId,
data = lists:flatten(lists:sublist(B64, length(B64)-1)),
sum = list_to_integer(Sum),
domain = Domain
};

% mfz.wiztb.onsgmcq.40966-0.id-372571.up.p.example.com
% B64._Nonce-Sum.id-SessionId.up.Domain
decode({domain, {a, [Base64Nonce, Sum, "id", SessionId, "up"|Domain]}}, Domains) ->
decode({domain, {a, [Base64Nonce, Sum, "id", SessionId, "up"|Domain]}},
#state{d = Domains}) ->
true = check_dn(Domain, Domains),

B64 = string:tokens(Base64Nonce, "."),
Expand All @@ -193,9 +236,46 @@ decode({domain, {a, [Base64Nonce, Sum, "id", SessionId, "up"|Domain]}}, Domains)
domain = Domain
};

% 0-29941.id-10498.d.192.168.100.101.s.p.example.com
% Sum-Nonce.id-SessionId.d.IP1.IP2.IP3.IP4.Domain
%
% 0-29941.id-10498.d.192.168.100.101-2222.x.p.example.com
% Sum-Nonce.id-SessionId.d.IP1.IP2.IP3.IP4-Port.x.Domain
decode({domain, {_Type, [Sum, _Nonce, "id", SessionId, "d",
IP1, IP2, IP3, IP4, Port, "x"|Domain]}},
#state{d = Domains, acf = true, acl = ACL}) ->
true = check_dn(Domain, Domains),
true = check_acl({IP1,IP2,IP3,IP4}, ACL),

Forward = forward({{IP1,IP2,IP3,IP4},Port}),

#seds{
type = down,
forward = Forward,
id = SessionId,
sum = list_to_sum(Sum),
domain = Domain
};
decode({domain, {_Type, [Sum, _Nonce, "id", SessionId, "d",
IP1, IP2, IP3, IP4, "x"|Domain]}},
#state{d = Domains, acf = true, acl = ACL}) ->
true = check_dn(Domain, Domains),
true = check_acl({IP1,IP2,IP3,IP4}, ACL),

Forward = forward({{IP1,IP2,IP3,IP4}, 22}),

#seds{
type = down,
forward = Forward,
id = SessionId,
sum = list_to_sum(Sum),
domain = Domain
};

% 0-29941.id-10498.down.s.p.example.com
% Sum-Nonce.id-SessionId.down.Domain
decode({domain, {_Type, [Sum, _Nonce, "id", SessionId, "down"|Domain]}}, Domains) ->
decode({domain, {_Type, [Sum, _Nonce, "id", SessionId, "down"|Domain]}},
#state{d = Domains}) ->
true = check_dn(Domain, Domains),

{Forward, Id} = forward(list_to_integer(SessionId)),
Expand All @@ -204,7 +284,7 @@ decode({domain, {_Type, [Sum, _Nonce, "id", SessionId, "down"|Domain]}}, Domains
type = down,
forward = Forward,
id = Id,
sum = list_to_integer(lists:reverse(tl(lists:reverse(Sum)))),
sum = list_to_sum(Sum),
domain = Domain
};

Expand All @@ -219,15 +299,15 @@ decode({dns_rec, #dns_rec{
class = in
}|_]
}
}, Domains) ->
}, State) ->
{Prefix, Session} = lists:split(string:chr(Query, $-), Query),
decode({domain, {Type, [Prefix|string:tokens(Session, ".-")]}}, Domains);
decode({domain, {Type, [Prefix|string:tokens(Session, ".-")]}}, State);

decode({binary, Data}, Domains) ->
decode({binary, Data}, State) ->
{ok, Query} = inet_dns:decode(Data),
{Query, decode({dns_rec, Query}, Domains)};
decode(Data, Domains) ->
try decode({binary, Data}, Domains) of
{Query, decode({dns_rec, Query}, State)};
decode(Data, State) ->
try decode({binary, Data}, State) of
Query ->
Query
catch
Expand All @@ -243,6 +323,13 @@ decode(Data, Domains) ->
check_dn(Domain, Domains) ->
[ N || N <- Domains, lists:suffix(N, Domain) ] /= [].

check_acl({IP1,IP2,IP3,IP4}, ACL) ->
[ N || N <- ACL, lists:prefix(N, [IP1,IP2,IP3,IP4]) ] == [].

% Remove the trailing dash and convert to an integer
list_to_sum(N) when is_list(N) ->
list_to_integer(lists:reverse(tl(lists:reverse(N)))).

config(Key, Cfg) ->
{ok, Map} = file:consult(privpath(Cfg)),
proplists:get_value(Key, Map).
Expand Down

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