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erlang
3542-Verify-DNS-reply.patch
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File 3542-Verify-DNS-reply.patch of Package erlang
From 0fdcb294d94f6d8443a4d3d7095cd524f8b128ec Mon Sep 17 00:00:00 2001 From: Raimo Niskanen <raimo@erlang.org> Date: Thu, 15 Apr 2021 14:00:22 +0200 Subject: [PATCH 2/8] Verify DNS reply --- lib/kernel/src/inet_res.erl | 103 +++++++++++++++++++++++------------- 1 file changed, 66 insertions(+), 37 deletions(-) diff --git a/lib/kernel/src/inet_res.erl b/lib/kernel/src/inet_res.erl index 4e71944492..1b6344f372 100644 --- a/lib/kernel/src/inet_res.erl +++ b/lib/kernel/src/inet_res.erl @@ -382,7 +382,7 @@ gethostbyaddr_tm(_,_) -> {error, formerr}. %% 2. the list of alternative name servers %% res_gethostbyaddr(Addr, IP, Timer) -> - case res_query(Addr, in, ptr, [], Timer) of + case res_query(Addr, in, ?S_PTR, [], Timer) of {ok, Rec} -> inet_db:res_gethostbyaddr(IP, Rec); {error,{qfmterror,_}} -> {error,einval}; @@ -649,6 +649,7 @@ make_query(Dname, Class, Type, Opts) -> make_query(Dname, Class, Type, Options, Edns) -> Id = inet_db:res_option(next_id), Recurse = Options#options.recurse, + RD = Recurse =:= 1 orelse Recurse =:= true, % (0 | 1 | true | false) ARList = case Edns of false -> []; _ -> @@ -656,17 +657,18 @@ make_query(Dname, Class, Type, Options, Edns) -> [#dns_rr_opt{udp_payload_size=PSz, version=Edns}] end, - Msg = #dns_rec{header=#dns_header{id=Id, + Msg = #dns_rec{header=#dns_header{id=Id, + qr=false, opcode='query', - rd=Recurse, + rd=RD, rcode=?NOERROR}, - qdlist=[#dns_query{domain=Dname, - type=Type, - class=Class}], + qdlist=[#dns_query{domain=Dname, + type=Type, + class=Class}], arlist=ARList}, ?verbose(Options#options.verbose, "Query: ~p~n", [dns_msg(Msg)]), Buffer = inet_dns:encode(Msg), - {Id, Buffer}. + {Msg, Buffer}. %% -------------------------------------------------------------------------- %% socket helpers @@ -820,13 +822,13 @@ query_nss_edns( #q{options = #options{ udp_payload_size = PSz}=Options, - edns = {Id,Buffer}}=Q, + edns = EDNSQuery}=Q, [NsSpec|NSs], Timer, Retry, I, S_0, Reason, RetryNSs) -> %% {IP,Port} = NS = servfail_retry_wait(NsSpec), {S,Result} = query_ns( - S_0, Id, Buffer, IP, Port, Timer, Retry, I, Options, PSz), + S_0, EDNSQuery, IP, Port, Timer, Retry, I, Options, PSz), case Result of {error,{E,_}} when E =:= qfmterror; @@ -848,19 +850,21 @@ query_nss_edns( end. query_nss_dns( - #q{dns = Qdns}=Q_0, + #q{dns = DNSQuery_0}=Q_0, [NsSpec|NSs], Timer, Retry, I, S_0, Reason, RetryNSs) -> %% {IP,Port} = NS = servfail_retry_wait(NsSpec), #q{options = Options, - dns = {Id,Buffer}}=Q = + dns = DNSQuery}=Q = if - is_function(Qdns, 0) -> Q_0#q{dns=Qdns()}; - true -> Q_0 + is_function(DNSQuery_0, 0) -> + Q_0#q{dns=DNSQuery_0()}; + true -> + Q_0 end, {S,Result} = query_ns( - S_0, Id, Buffer, IP, Port, Timer, Retry, I, Options, ?PACKETSZ), + S_0, DNSQuery, IP, Port, Timer, Retry, I, Options, ?PACKETSZ), query_nss_result( Q, NSs, Timer, Retry, I, S, Reason, RetryNSs, NS, Result). @@ -952,14 +956,14 @@ query_retries_error(#q{options=#options{nxdomain_reply=NxReply}}, S, Reason) -> end. -query_ns(S0, Id, Buffer, IP, Port, Timer, Retry, I, +query_ns(S0, {Msg, Buffer}, IP, Port, Timer, Retry, I, #options{timeout=Tm,usevc=UseVC,verbose=Verbose}, PSz) -> case UseVC orelse iolist_size(Buffer) > PSz of true -> TcpTimeout = inet:timeout(Tm*5, Timer), {S0, - query_tcp(TcpTimeout, Id, Buffer, IP, Port, Verbose)}; + query_tcp(TcpTimeout, Msg, Buffer, IP, Port, Verbose)}; false -> case udp_open(S0, IP) of {ok,S} -> @@ -967,13 +971,13 @@ query_ns(S0, Id, Buffer, IP, Port, Timer, Retry, I, inet:timeout( (Tm * (1 bsl I)) div Retry, Timer), case query_udp( - S, Id, Buffer, IP, Port, UdpTimeout, Verbose) + S, Msg, Buffer, IP, Port, UdpTimeout, Verbose) of {ok,#dns_rec{header=H}} when H#dns_header.tc -> TcpTimeout = inet:timeout(Tm*5, Timer), {S, query_tcp( - TcpTimeout, Id, Buffer, IP, Port, Verbose)}; + TcpTimeout, Msg, Buffer, IP, Port, Verbose)}; {error, econnrefused} = Err -> ok = udp_close(S), {#sock{}, Err}; @@ -984,9 +988,9 @@ query_ns(S0, Id, Buffer, IP, Port, Timer, Retry, I, end end. -query_udp(_S, _Id, _Buffer, _IP, _Port, 0, _Verbose) -> +query_udp(_S, _Msg, _Buffer, _IP, _Port, 0, _Verbose) -> timeout; -query_udp(S, Id, Buffer, IP, Port, Timeout, Verbose) -> +query_udp(S, Msg, Buffer, IP, Port, Timeout, Verbose) -> ?verbose(Verbose, "Try UDP server : ~p:~p (timeout=~w)\n", [IP,Port,Timeout]), case @@ -999,7 +1003,7 @@ query_udp(S, Id, Buffer, IP, Port, Timeout, Verbose) -> Decode = fun ({RecIP,RecPort,Answer}) when RecIP =:= IP, RecPort =:= Port -> - case decode_answer(Answer, Id, Verbose) of + case decode_answer(Answer, Msg, Verbose) of {error,badid} -> false; Reply -> @@ -1020,9 +1024,9 @@ query_udp(S, Id, Buffer, IP, Port, Timeout, Verbose) -> {error,econnrefused} end. -query_tcp(0, _Id, _Buffer, _IP, _Port, _Verbose) -> +query_tcp(0, _Msg, _Buffer, _IP, _Port, _Verbose) -> timeout; -query_tcp(Timeout, Id, Buffer, IP, Port, Verbose) -> +query_tcp(Timeout, Msg, Buffer, IP, Port, Verbose) -> ?verbose(Verbose, "Try TCP server : ~p:~p (timeout=~w)\n", [IP, Port, Timeout]), Family = case IP of @@ -1038,7 +1042,7 @@ query_tcp(Timeout, Id, Buffer, IP, Port, Verbose) -> case gen_tcp:recv(S, 0, Timeout) of {ok, Answer} -> gen_tcp:close(S), - case decode_answer(Answer, Id, Verbose) of + case decode_answer(Answer, Msg, Verbose) of {ok, _} = OK -> OK; {error, badid} -> {error, servfail}; Error -> Error @@ -1062,38 +1066,63 @@ query_tcp(Timeout, Id, Buffer, IP, Port, Verbose) -> _:_ -> {error, einval} end. -decode_answer(Answer, Id, Verbose) -> +decode_answer(Answer, Q_Msg, Verbose) -> case inet_dns:decode(Answer) of - {ok, Msg} -> + {ok, #dns_rec{header = H, arlist = ARList} = Msg} -> ?verbose(Verbose, "Got reply: ~p~n", [dns_msg(Msg)]), - E = case lists:keyfind(dns_rr_opt, 1, Msg#dns_rec.arlist) of + E = case lists:keyfind(dns_rr_opt, 1, ARList) of false -> 0; #dns_rr_opt{ext_rcode=ExtRCode} -> ExtRCode end, - H = Msg#dns_rec.header, RCode = (E bsl 4) bor H#dns_header.rcode, case RCode of - ?NOERROR -> - if H#dns_header.id =/= Id -> - {error,badid}; - length(Msg#dns_rec.qdlist) =/= 1 -> - {error,{noquery,Msg}}; - true -> - {ok, Msg} - end; + ?NOERROR -> decode_answer_noerror(Q_Msg, Msg, H); ?FORMERR -> {error,{qfmterror,Msg}}; ?SERVFAIL -> {error,{servfail,Msg}}; ?NXDOMAIN -> {error,{nxdomain,Msg}}; ?NOTIMP -> {error,{notimp,Msg}}; ?REFUSED -> {error,{refused,Msg}}; ?BADVERS -> {error,{badvers,Msg}}; - _ -> {error,{unknown,Msg}} + _ -> {error,{unknown,Msg}} end; {error, formerr} = Error -> ?verbose(Verbose, "Got reply: decode format error~n", []), Error end. +decode_answer_noerror( + #dns_rec{header = Q_H, qdlist = [Q_RR]}, + #dns_rec{qdlist = QDList} = Msg, + H) -> + %% Validate the reply + if + H#dns_header.id =/= Q_H#dns_header.id -> + {error,badid}; + H#dns_header.qr =/= true; + H#dns_header.opcode =/= Q_H#dns_header.opcode; + H#dns_header.rd =/= Q_H#dns_header.rd -> + {error,{unknown,Msg}}; + true -> + case QDList of + [RR] -> + case + (RR#dns_query.class =:= Q_RR#dns_query.class) + andalso + (RR#dns_query.type =:= Q_RR#dns_query.type) + andalso + (inet_db:tolower(RR#dns_query.domain) =:= + inet_db:tolower(Q_RR#dns_query.domain)) + of + true -> + {ok, Msg}; + false -> + {error,{noquery,Msg}} + end; + _ when is_list(QDList) -> + {error,{noquery,Msg}} + end + end. + %% %% Transform domain name or address %% 1. "a.b.c" => -- 2.31.1
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