aboutsummaryrefslogtreecommitdiffstats
path: root/lib/kernel/src/inet_res.erl
diff options
context:
space:
mode:
Diffstat (limited to 'lib/kernel/src/inet_res.erl')
-rw-r--r--lib/kernel/src/inet_res.erl203
1 files changed, 118 insertions, 85 deletions
diff --git a/lib/kernel/src/inet_res.erl b/lib/kernel/src/inet_res.erl
index de0f23bf24..93563c6011 100644
--- a/lib/kernel/src/inet_res.erl
+++ b/lib/kernel/src/inet_res.erl
@@ -1,7 +1,7 @@
%%
%% %CopyrightBegin%
%%
-%% Copyright Ericsson AB 1997-2010. All Rights Reserved.
+%% Copyright Ericsson AB 1997-2011. All Rights Reserved.
%%
%% The contents of this file are subject to the Erlang Public License,
%% Version 1.1, (the "License"); you may not use this file except in
@@ -539,27 +539,41 @@ udp_send(#sock{inet=I}, {A,B,C,D}=IP, Port, Buffer)
when ?ip(A,B,C,D), ?port(Port) ->
gen_udp:send(I, IP, Port, Buffer).
-udp_recv(#sock{inet6=I}, {A,B,C,D,E,F,G,H}=IP, Port, Timeout)
+udp_recv(#sock{inet6=I}, {A,B,C,D,E,F,G,H}=IP, Port, Timeout, Decode)
when ?ip6(A,B,C,D,E,F,G,H), ?port(Port) ->
- do_udp_recv(fun(T) -> gen_udp:recv(I, 0, T) end, IP, Port, Timeout);
-udp_recv(#sock{inet=I}, {A,B,C,D}=IP, Port, Timeout)
+ do_udp_recv(I, IP, Port, Timeout, Decode, erlang:now(), Timeout);
+udp_recv(#sock{inet=I}, {A,B,C,D}=IP, Port, Timeout, Decode)
when ?ip(A,B,C,D), ?port(Port) ->
- do_udp_recv(fun(T) -> gen_udp:recv(I, 0, T) end, IP, Port, Timeout).
-
-do_udp_recv(Recv, IP, Port, Timeout) ->
- do_udp_recv(Recv, IP, Port, Timeout,
- if Timeout =/= 0 -> erlang:now(); true -> undefined end).
-
-do_udp_recv(Recv, IP, Port, Timeout, Then) ->
- case Recv(Timeout) of
- {ok,{IP,Port,Answer}} ->
- {ok,Answer,erlang:max(0, Timeout - now_ms(erlang:now(), Then))};
- {ok,_} when Timeout =:= 0 ->
- {error,timeout};
- {ok,_} ->
- Now = erlang:now(),
- T = erlang:max(0, Timeout - now_ms(Now, Then)),
- do_udp_recv(Recv, IP, Port, T, Now);
+ do_udp_recv(I, IP, Port, Timeout, Decode, erlang:now(), Timeout).
+
+do_udp_recv(_I, _IP, _Port, 0, _Decode, _Start, _T) ->
+ timeout;
+do_udp_recv(I, IP, Port, Timeout, Decode, Start, T) ->
+ case gen_udp:recv(I, 0, T) of
+ {ok,Reply} ->
+ case Decode(Reply) of
+ false when T =:= 0 ->
+ %% This is a compromize between the hard way i.e
+ %% in the clause below if NewT becomes 0 bailout
+ %% immediately and risk that the right reply lies
+ %% ahead after some bad id replies, and the
+ %% forgiving way i.e go on with Timeout 0 until
+ %% the right reply comes or no reply (timeout)
+ %% which opens for a DOS attack by a malicious
+ %% DNS server flooding with bad id replies causing
+ %% an infinite loop here.
+ %%
+ %% Timeout is used as a sanity limit counter
+ %% just to put an end to the loop.
+ NewTimeout = erlang:max(0, Timeout - 50),
+ do_udp_recv(I, IP, Port, NewTimeout, Decode, Start, T);
+ false ->
+ Now = erlang:now(),
+ NewT = erlang:max(0, Timeout - now_ms(Now, Start)),
+ do_udp_recv(I, IP, Port, Timeout, Decode, Start, NewT);
+ Result ->
+ Result
+ end;
Error -> Error
end.
@@ -580,6 +594,17 @@ udp_close(#sock{inet=I,inet6=I6}) ->
%% end
%% end
%%
+%% But that man page also says dig always use num_servers = 1.
+%%
+%% Our man page says: timeout/retry, then double for next retry, i.e
+%% for i = 0 to retry - 1
+%% foreach nameserver
+%% send query
+%% wait((time * (2**i)) / retry)
+%% end
+%% end
+%%
+%% And that is what the code seems to do, now fixed, hopefully...
do_query(_Q, [], _Timer) ->
{error,nxdomain};
@@ -589,19 +614,16 @@ do_query(#q{options=#options{retry=Retry}}=Q, NSs, Timer) ->
query_retries(_Q, _NSs, _Timer, Retry, Retry, S) ->
udp_close(S),
{error,timeout};
+query_retries(_Q, [], _Timer, _Retry, _I, S) ->
+ udp_close(S),
+ {error,timeout};
query_retries(Q, NSs, Timer, Retry, I, S0) ->
- Num = length(NSs),
- if Num =:= 0 ->
- udp_close(S0),
- {error,timeout};
- true ->
- case query_nss(Q, NSs, Timer, Retry, I, S0, []) of
- {S,{noanswer,ErrNSs}} -> %% remove unreachable nameservers
- query_retries(Q, NSs--ErrNSs, Timer, Retry, I+1, S);
- {S,Result} ->
- udp_close(S),
- Result
- end
+ case query_nss(Q, NSs, Timer, Retry, I, S0, []) of
+ {S,{noanswer,ErrNSs}} -> %% remove unreachable nameservers
+ query_retries(Q, NSs--ErrNSs, Timer, Retry, I+1, S);
+ {S,Result} ->
+ udp_close(S),
+ Result
end.
query_nss(_Q, [], _Timer, _Retry, _I, S, ErrNSs) ->
@@ -611,13 +633,13 @@ query_nss(#q{edns=undefined}=Q, NSs, Timer, Retry, I, S, ErrNSs) ->
query_nss(Q, NSs, Timer, Retry, I, S, ErrNSs) ->
query_nss_edns(Q, NSs, Timer, Retry, I, S, ErrNSs).
-query_nss_edns(#q{options=#options{udp_payload_size=PSz}=Options,
- edns={Id,Buffer}}=Q,
- [{IP,Port}=NS|NSs]=NSs0, Timer, Retry, I, S0, ErrNSs) ->
- {S,Res}=Reply = query_ns(S0, Id, Buffer, IP, Port, Timer,
- Retry, I, Options, PSz),
+query_nss_edns(
+ #q{options=#options{udp_payload_size=PSz}=Options,edns={Id,Buffer}}=Q,
+ [{IP,Port}=NS|NSs]=NSs0, Timer, Retry, I, S0, ErrNSs) ->
+ {S,Res}=Reply =
+ query_ns(S0, Id, Buffer, IP, Port, Timer, Retry, I, Options, PSz),
case Res of
- timeout -> {S,{error,timeout}};
+ timeout -> {S,{error,timeout}}; % Bailout timeout
{ok,_} -> Reply;
{error,{nxdomain,_}} -> Reply;
{error,{E,_}} when E =:= qfmterror; E =:= notimp; E =:= servfail;
@@ -629,17 +651,19 @@ query_nss_edns(#q{options=#options{udp_payload_size=PSz}=Options,
query_nss(Q, NSs, Timer, Retry, I, S, ErrNSs)
end.
-query_nss_dns(#q{dns=Qdns}=Q0, [{IP,Port}=NS|NSs],
- Timer, Retry, I, S0, ErrNSs) ->
+query_nss_dns(
+ #q{dns=Qdns}=Q0,
+ [{IP,Port}=NS|NSs], Timer, Retry, I, S0, ErrNSs) ->
#q{options=Options,dns={Id,Buffer}}=Q =
if
is_function(Qdns, 0) -> Q0#q{dns=Qdns()};
true -> Q0
end,
- {S,Res}=Reply = query_ns(S0, Id, Buffer, IP, Port, Timer,
- Retry, I, Options, ?PACKETSZ),
+ {S,Res}=Reply =
+ query_ns(
+ S0, Id, Buffer, IP, Port, Timer, Retry, I, Options, ?PACKETSZ),
case Res of
- timeout -> {S,{error,timeout}};
+ timeout -> {S,{error,timeout}}; % Bailout timeout
{ok,_} -> Reply;
{error,{E,_}} when E =:= nxdomain; E =:= qfmterror -> Reply;
{error,E} when E =:= fmt; E =:= enetunreach; E =:= econnrefused ->
@@ -653,48 +677,66 @@ query_ns(S0, Id, Buffer, IP, Port, Timer, Retry, I,
PSz) ->
case UseVC orelse iolist_size(Buffer) > PSz of
true ->
- {S0,query_tcp(Tm, Id, Buffer, IP, Port, Timer, Verbose)};
+ TcpTimeout = inet:timeout(Tm*5, Timer),
+ {S0,query_tcp(TcpTimeout, Id, Buffer, IP, Port, Verbose)};
false ->
case udp_open(S0, IP) of
{ok,S} ->
- {S,case query_udp(S, Id, Buffer, IP, Port, Timer,
- Retry, I, Tm, Verbose) of
- {ok,#dns_rec{header=H}} when H#dns_header.tc ->
- query_tcp(Tm, Id, Buffer,
- IP, Port, Timer, Verbose);
- Reply -> Reply
- end};
+ Timeout =
+ inet:timeout( (Tm * (1 bsl I)) div Retry, Timer),
+ {S,
+ case query_udp(
+ S, Id, Buffer, IP, Port, Timeout, Verbose) of
+ {ok,#dns_rec{header=H}} when H#dns_header.tc ->
+ TcpTimeout = inet:timeout(Tm*5, Timer),
+ query_tcp(
+ TcpTimeout, Id, Buffer, IP, Port, Verbose);
+ Reply -> Reply
+ end};
Error ->
{S0,Error}
end
end.
-query_udp(S, Id, Buffer, IP, Port, Timer, Retry, I, Tm, Verbose) ->
- Timeout = inet:timeout( (Tm * (1 bsl I)) div Retry, Timer),
+query_udp(_S, _Id, _Buffer, _IP, _Port, 0, Verbose) ->
+ timeout;
+query_udp(S, Id, Buffer, IP, Port, Timeout, Verbose) ->
?verbose(Verbose, "Try UDP server : ~p:~p (timeout=~w)\n",
- [IP, Port, Timeout]),
- udp_connect(S, IP, Port),
- udp_send(S, IP, Port, Buffer),
- query_udp_recv(S, IP, Port, Id, Timeout, Verbose).
-
-query_udp_recv(S, IP, Port, Id, Timeout, Verbose) ->
- case udp_recv(S, IP, Port, Timeout) of
- {ok,Answer,T} ->
- case decode_answer(Answer, Id, Verbose) of
- {error, badid} ->
- query_udp_recv(S, IP, Port, Id, T, Verbose);
- Reply -> Reply
+ [IP,Port,Timeout]),
+ case
+ case udp_connect(S, IP, Port) of
+ ok ->
+ udp_send(S, IP, Port, Buffer);
+ E1 ->
+ E1 end of
+ ok ->
+ Decode =
+ fun ({RecIP,RecPort,Answer})
+ when RecIP =:= IP, RecPort =:= Port ->
+ case decode_answer(Answer, Id, Verbose) of
+ {error,badid} ->
+ false;
+ Reply ->
+ Reply
+ end;
+ ({_,_,_}) ->
+ false
+ end,
+ case udp_recv(S, IP, Port, Timeout, Decode) of
+ {ok,_}=Result ->
+ Result;
+ E2 ->
+ ?verbose(Verbose, "UDP server error: ~p\n", [E2]),
+ E2
end;
- {error, timeout} when Timeout =:= 0 ->
- ?verbose(Verbose, "UDP server timeout\n", []),
- timeout;
- Error ->
- ?verbose(Verbose, "UDP server error: ~p\n", [Error]),
- Error
+ E3 ->
+ ?verbose(Verbose, "UDP send failed: ~p\n", [E3]),
+ {error,econnrefused}
end.
-query_tcp(Tm, Id, Buffer, IP, Port, Timer, Verbose) ->
- Timeout = inet:timeout(Tm*5, Timer),
+query_tcp(0, _Id, _Buffer, _IP, _Port, Verbose) ->
+ timeout;
+query_tcp(Timeout, Id, Buffer, IP, Port, Verbose) ->
?verbose(Verbose, "Try TCP server : ~p:~p (timeout=~w)\n",
[IP, Port, Timeout]),
Family = case IP of
@@ -716,19 +758,10 @@ query_tcp(Tm, Id, Buffer, IP, Port, Timer, Verbose) ->
end;
Error ->
gen_tcp:close(S),
- case Error of
- {error, timeout} when Timeout =:= 0 ->
- ?verbose(Verbose, "TCP server recv timeout\n", []),
- timeout;
- _ ->
- ?verbose(Verbose, "TCP server recv error: ~p\n",
- [Error]),
- Error
- end
+ ?verbose(Verbose, "TCP server recv error: ~p\n",
+ [Error]),
+ Error
end;
- {error, timeout} when Timeout =:= 0 ->
- ?verbose(Verbose, "TCP server connect timeout\n", []),
- timeout;
Error ->
?verbose(Verbose, "TCP server error: ~p\n", [Error]),
Error
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-14 17:19:33 +0000