%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 1997-2016. All Rights Reserved.
%%
%% Licensed under the Apache License, Version 2.0 (the "License");
%% you may not use this file except in compliance with the License.
%% You may obtain a copy of the License at
%%
%% http://www.apache.org/licenses/LICENSE-2.0
%%
%% Unless required by applicable law or agreed to in writing, software
%% distributed under the License is distributed on an "AS IS" BASIS,
%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
%% See the License for the specific language governing permissions and
%% limitations under the License.
%%
%% %CopyrightEnd%
%%
%% RFC 1035, 2671, 2782, 2915.
%%
-module(inet_res).
%-compile(export_all).
-export([gethostbyname/1, gethostbyname/2, gethostbyname/3,
gethostbyname_tm/3]).
-export([gethostbyaddr/1, gethostbyaddr/2,
gethostbyaddr_tm/2]).
-export([getbyname/2, getbyname/3,
getbyname_tm/3]).
-export([resolve/3, resolve/4, resolve/5]).
-export([lookup/3, lookup/4, lookup/5]).
-export([dns_msg/1]).
-export([nslookup/3, nslookup/4]).
-export([nnslookup/4, nnslookup/5]).
-include_lib("kernel/include/inet.hrl").
-include("inet_res.hrl").
-include("inet_dns.hrl").
-include("inet_int.hrl").
-define(verbose(Cond, Format, Args),
case begin Cond end of
true -> io:format(begin Format end, begin Args end);
false -> ok
end).
-type res_option() ::
{alt_nameservers, [nameserver()]}
| {edns, 0 | false}
| {inet6, boolean()}
| {nameservers, [nameserver()]}
| {recurse, boolean()}
| {retry, integer()}
| {timeout, integer()}
| {udp_payload_size, integer()}
| {usevc, boolean()}.
-type nameserver() :: {inet:ip_address(), Port :: 1..65535}.
-type res_error() :: formerr | qfmterror | servfail | nxdomain |
notimp | refused | badvers | timeout.
-type dns_name() :: string().
-type rr_type() :: a | aaaa | cname | gid | hinfo | ns | mb | md | mg | mf
| minfo | mx | naptr | null | ptr | soa | spf | srv | txt
| uid | uinfo | unspec | wks.
-type dns_class() :: in | chaos | hs | any.
-type dns_msg() :: term().
-type dns_data() ::
dns_name()
| inet:ip4_address()
| inet:ip6_address()
| {MName :: dns_name(),
RName :: dns_name(),
Serial :: integer(),
Refresh :: integer(),
Retry :: integer(),
Expiry :: integer(),
Minimum :: integer()}
| {inet:ip4_address(), Proto :: integer(), BitMap :: binary()}
| {CpuString :: string(), OsString :: string()}
| {RM :: dns_name(), EM :: dns_name()}
| {Prio :: integer(), dns_name()}
| {Prio :: integer(),Weight :: integer(),Port :: integer(),dns_name()}
| {Order :: integer(),Preference :: integer(),Flags :: string(),
Services :: string(),Regexp :: string(), dns_name()}
| [string()]
| binary().
%% --------------------------------------------------------------------------
%% resolve:
%%
%% Nameserver query
%%
-spec resolve(Name, Class, Type) -> {ok, dns_msg()} | Error when
Name :: dns_name() | inet:ip_address(),
Class :: dns_class(),
Type :: rr_type(),
Error :: {error, Reason} | {error,{Reason,dns_msg()}},
Reason :: inet:posix() | res_error().
resolve(Name, Class, Type) ->
resolve(Name, Class, Type, [], infinity).
-spec resolve(Name, Class, Type, Opts) ->
{ok, dns_msg()} | Error when
Name :: dns_name() | inet:ip_address(),
Class :: dns_class(),
Type :: rr_type(),
Opts :: [Opt],
Opt :: res_option() | verbose | atom(),
Error :: {error, Reason} | {error,{Reason,dns_msg()}},
Reason :: inet:posix() | res_error().
resolve(Name, Class, Type, Opts) ->
resolve(Name, Class, Type, Opts, infinity).
-spec resolve(Name, Class, Type, Opts, Timeout) ->
{ok, dns_msg()} | Error when
Name :: dns_name() | inet:ip_address(),
Class :: dns_class(),
Type :: rr_type(),
Opts :: [Opt],
Opt :: res_option() | verbose | atom(),
Timeout :: timeout(),
Error :: {error, Reason} | {error,{Reason,dns_msg()}},
Reason :: inet:posix() | res_error().
resolve(Name, Class, Type, Opts, Timeout) ->
case nsdname(Name) of
{ok, Nm} ->
Timer = inet:start_timer(Timeout),
Res = res_query(Nm, Class, Type, Opts, Timer),
_ = inet:stop_timer(Timer),
Res;
Error ->
Error
end.
%% --------------------------------------------------------------------------
%% lookup:
%%
%% Convenience wrapper to resolve/3,4,5 that filters out all answer data
%% fields of the class and type asked for.
-spec lookup(Name, Class, Type) -> [dns_data()] when
Name :: dns_name() | inet:ip_address(),
Class :: dns_class(),
Type :: rr_type().
lookup(Name, Class, Type) ->
lookup(Name, Class, Type, []).
-spec lookup(Name, Class, Type, Opts) -> [dns_data()] when
Name :: dns_name() | inet:ip_address(),
Class :: dns_class(),
Type :: rr_type(),
Opts :: [res_option() | verbose].
lookup(Name, Class, Type, Opts) ->
lookup(Name, Class, Type, Opts, infinity).
-spec lookup(Name, Class, Type, Opts, Timeout) -> [dns_data()] when
Name :: dns_name() | inet:ip_address(),
Class :: dns_class(),
Type :: rr_type(),
Opts :: [res_option() | verbose],
Timeout :: timeout().
lookup(Name, Class, Type, Opts, Timeout) ->
lookup_filter(resolve(Name, Class, Type, Opts, Timeout),
Class, Type).
lookup_filter({ok,#dns_rec{anlist=Answers}}, Class, Type) ->
[A#dns_rr.data || A <- Answers,
Class =:= any orelse A#dns_rr.class =:= Class,
Type =:= any orelse A#dns_rr.type =:= Type];
lookup_filter({error,_}, _, _) -> [].
%% --------------------------------------------------------------------------
%% nslookup:
%%
%% Do a general nameserver lookup
%%
%% Perform nslookup on standard config !!
%%
%% To be deprecated
-spec nslookup(Name, Class, Type) -> {ok, dns_msg()} | {error, Reason} when
Name :: dns_name() | inet:ip_address(),
Class :: dns_class(),
Type :: rr_type(),
Reason :: inet:posix() | res_error().
nslookup(Name, Class, Type) ->
do_nslookup(Name, Class, Type, [], infinity).
-spec nslookup(Name, Class, Type, Timeout) ->
{ok, dns_msg()} | {error, Reason} when
Name :: dns_name() | inet:ip_address(),
Class :: dns_class(),
Type :: rr_type(),
Timeout :: timeout(),
Reason :: inet:posix() | res_error();
(Name, Class, Type, Nameservers) ->
{ok, dns_msg()} | {error, Reason} when
Name :: dns_name() | inet:ip_address(),
Class :: dns_class(),
Type :: rr_type(),
Nameservers :: [nameserver()],
Reason :: inet:posix() | res_error().
nslookup(Name, Class, Type, Timeout) when is_integer(Timeout), Timeout >= 0 ->
do_nslookup(Name, Class, Type, [], Timeout);
nslookup(Name, Class, Type, NSs) -> % For backwards compatibility
nnslookup(Name, Class, Type, NSs). % with OTP R6B only
-spec nnslookup(Name, Class, Type, Nameservers) ->
{ok, dns_msg()} | {error, Reason} when
Name :: dns_name() | inet:ip_address(),
Class :: dns_class(),
Type :: rr_type(),
Nameservers :: [nameserver()],
Reason :: inet:posix().
nnslookup(Name, Class, Type, NSs) ->
nnslookup(Name, Class, Type, NSs, infinity).
-spec nnslookup(Name, Class, Type, Nameservers, Timeout) ->
{ok, dns_msg()} | {error, Reason} when
Name :: dns_name() | inet:ip_address(),
Class :: dns_class(),
Type :: rr_type(),
Timeout :: timeout(),
Nameservers :: [nameserver()],
Reason :: inet:posix().
nnslookup(Name, Class, Type, NSs, Timeout) ->
do_nslookup(Name, Class, Type, [{nameservers,NSs}], Timeout).
do_nslookup(Name, Class, Type, Opts, Timeout) ->
case resolve(Name, Class, Type, Opts, Timeout) of
{error,{qfmterror,_}} -> {error,einval};
{error,{Reason,_}} -> {error,Reason};
Result -> Result
end.
%% --------------------------------------------------------------------------
%% options record
%%
-record(options, { % These must be sorted!
alt_nameservers,edns,inet6,nameservers,recurse,
retry,timeout,udp_payload_size,usevc,
verbose}). % this is a local option, not in inet_db
%%
%% Opts when is_list(Opts) -> #options{}
make_options(Opts0) ->
Opts = [if is_atom(Opt) ->
case atom_to_list(Opt) of
"no"++X -> {list_to_atom(X),false};
_ -> {Opt,true}
end;
true -> Opt
end || Opt <- Opts0],
%% If the caller gives the nameservers option, the inet_db
%% alt_nameservers option should be regarded as empty, i.e
%% use only the nameservers the caller supplies.
SortedOpts =
lists:ukeysort(1,
case lists:keymember(nameservers, 1, Opts) of
true ->
case lists:keymember(alt_nameservers, 1, Opts) of
false ->
[{alt_nameservers,[]}|Opts];
true ->
Opts
end;
false ->
Opts
end),
SortedNames = record_info(fields, options),
inet_db:res_update_conf(),
list_to_tuple([options|make_options(SortedOpts, SortedNames)]).
make_options([_|_]=Opts0, []=Names0) ->
erlang:error(badarg, [Opts0,Names0]);
make_options([], []) -> [];
make_options([{verbose,Val}|Opts]=Opts0, [verbose|Names]=Names0) ->
if is_boolean(Val) ->
[Val|make_options(Opts, Names)];
true ->
erlang:error(badarg, [Opts0,Names0])
end;
make_options([{Opt,Val}|Opts]=Opts0, [Opt|Names]=Names0) ->
case inet_db:res_check_option(Opt, Val) of
true ->
[Val|make_options(Opts, Names)];
false ->
erlang:error(badarg, [Opts0,Names0])
end;
make_options(Opts, [verbose|Names]) ->
[false|make_options(Opts, Names)];
make_options(Opts, [Name|Names]) ->
[inet_db:res_option(Name)|make_options(Opts, Names)].
%% --------------------------------------------------------------------------
%%
%% gethostbyaddr(ip_address()) => {ok, hostent()} | {error, Reason}
%%
%% where ip_address() is {A,B,C,D} ipv4 address
%% | {A,B,C,D,E,F,G,H} ipv6 address
%% | string versions of the above
%% | atom version
%%
%% --------------------------------------------------------------------------
-spec gethostbyaddr(Address) -> {ok, Hostent} | {error, Reason} when
Address :: inet:ip_address(),
Hostent :: inet:hostent(),
Reason :: inet:posix() | res_error().
gethostbyaddr(IP) -> gethostbyaddr_tm(IP,false).
-spec gethostbyaddr(Address, Timeout) -> {ok, Hostent} | {error, Reason} when
Address :: inet:ip_address(),
Timeout :: timeout(),
Hostent :: inet:hostent(),
Reason :: inet:posix() | res_error().
gethostbyaddr(IP,Timeout) ->
Timer = inet:start_timer(Timeout),
Res = gethostbyaddr_tm(IP,Timer),
_ = inet:stop_timer(Timer),
Res.
gethostbyaddr_tm({A,B,C,D} = IP, Timer) when ?ip(A,B,C,D) ->
inet_db:res_update_conf(),
case inet_db:gethostbyaddr(IP) of
{ok, HEnt} -> {ok, HEnt};
_ -> res_gethostbyaddr(dn_in_addr_arpa(A,B,C,D), IP, Timer)
end;
%% ipv4 only ipv6 address
gethostbyaddr_tm({0,0,0,0,0,16#ffff,G,H},Timer) when is_integer(G+H) ->
gethostbyaddr_tm({G div 256, G rem 256, H div 256, H rem 256},Timer);
gethostbyaddr_tm({A,B,C,D,E,F,G,H} = IP, Timer) when ?ip6(A,B,C,D,E,F,G,H) ->
inet_db:res_update_conf(),
case inet_db:gethostbyaddr(IP) of
{ok, HEnt} -> {ok, HEnt};
_ -> res_gethostbyaddr(dn_ip6_int(A,B,C,D,E,F,G,H), IP, Timer)
end;
gethostbyaddr_tm(Addr,Timer) when is_list(Addr) ->
case inet_parse:address(Addr) of
{ok, IP} -> gethostbyaddr_tm(IP,Timer);
_Error -> {error, formerr}
end;
gethostbyaddr_tm(Addr,Timer) when is_atom(Addr) ->
gethostbyaddr_tm(atom_to_list(Addr),Timer);
gethostbyaddr_tm(_,_) -> {error, formerr}.
%%
%% Send the gethostbyaddr query to:
%% 1. the list of normal names servers
%% 2. the list of alternative name servers
%%
res_gethostbyaddr(Addr, IP, Timer) ->
case res_query(Addr, in, ptr, [], Timer) of
{ok, Rec} ->
inet_db:res_gethostbyaddr(IP, Rec);
{error,{qfmterror,_}} -> {error,einval};
{error,{Reason,_}} -> {error,Reason};
Error ->
Error
end.
%% --------------------------------------------------------------------------
%%
%% gethostbyname(domain_name()[,family [,Timer])
%% => {ok, hostent()} | {error, Reason}
%%
%% where domain_name() is domain string or atom
%%
%% Caches the answer.
%% --------------------------------------------------------------------------
-spec gethostbyname(Name) -> {ok, Hostent} | {error, Reason} when
Name :: dns_name(),
Hostent :: inet:hostent(),
Reason :: inet:posix() | res_error().
gethostbyname(Name) ->
case inet_db:res_option(inet6) of
true ->
gethostbyname_tm(Name, inet6, false);
false ->
gethostbyname_tm(Name, inet, false)
end.
-spec gethostbyname(Name, Family) -> {ok, Hostent} | {error, Reason} when
Name :: dns_name(),
Hostent :: inet:hostent(),
Family :: inet:address_family(),
Reason :: inet:posix() | res_error().
gethostbyname(Name,Family) ->
gethostbyname_tm(Name,Family,false).
-spec gethostbyname(Name, Family, Timeout) ->
{ok, Hostent} | {error, Reason} when
Name :: dns_name(),
Hostent :: inet:hostent(),
Timeout :: timeout(),
Family :: inet:address_family(),
Reason :: inet:posix() | res_error().
gethostbyname(Name,Family,Timeout) ->
Timer = inet:start_timer(Timeout),
Res = gethostbyname_tm(Name,Family,Timer),
_ = inet:stop_timer(Timer),
Res.
gethostbyname_tm(Name,inet,Timer) ->
getbyname_tm(Name,?S_A,Timer);
gethostbyname_tm(Name,inet6,Timer) ->
case getbyname_tm(Name,?S_AAAA,Timer) of
{ok,HEnt} -> {ok,HEnt};
{error,nxdomain} ->
case getbyname_tm(Name, ?S_A,Timer) of
{ok, HEnt} ->
%% rewrite to a ipv4 only ipv6 address
{ok,
HEnt#hostent {
h_addrtype = inet6,
h_length = 16,
h_addr_list =
lists:map(
fun({A,B,C,D}) ->
{0,0,0,0,0,16#ffff,A*256+B,C*256+D}
end, HEnt#hostent.h_addr_list)
}};
Error ->
Error
end;
Error ->
Error
end;
gethostbyname_tm(_Name, _Family, _Timer) ->
{error, einval}.
%% --------------------------------------------------------------------------
%%
%% getbyname(domain_name(), Type) => {ok, hostent()} | {error, Reason}
%%
%% where domain_name() is domain string and Type is ?S_A, ?S_MX ...
%%
%% Caches the answer.
%% --------------------------------------------------------------------------
-spec getbyname(Name, Type) -> {ok, Hostent} | {error, Reason} when
Name :: dns_name(),
Type :: rr_type(),
Hostent :: inet:hostent(),
Reason :: inet:posix() | res_error().
getbyname(Name, Type) ->
getbyname_tm(Name,Type,false).
-spec getbyname(Name, Type, Timeout) -> {ok, Hostent} | {error, Reason} when
Name :: dns_name(),
Type :: rr_type(),
Timeout :: timeout(),
Hostent :: inet:hostent(),
Reason :: inet:posix() | res_error().
getbyname(Name, Type, Timeout) ->
Timer = inet:start_timer(Timeout),
Res = getbyname_tm(Name, Type, Timer),
_ = inet:stop_timer(Timer),
Res.
getbyname_tm(Name, Type, Timer) when is_list(Name) ->
case type_p(Type) of
true ->
case inet_parse:visible_string(Name) of
false -> {error, formerr};
true ->
inet_db:res_update_conf(),
case inet_db:getbyname(Name, Type) of
{ok, HEnt} -> {ok, HEnt};
_ -> res_getbyname(Name, Type, Timer)
end
end;
false ->
{error, formerr}
end;
getbyname_tm(Name,Type,Timer) when is_atom(Name) ->
getbyname_tm(atom_to_list(Name), Type,Timer);
getbyname_tm(_, _, _) -> {error, formerr}.
type_p(Type) ->
lists:member(Type, [?S_A, ?S_AAAA, ?S_MX, ?S_NS,
?S_MD, ?S_MF, ?S_CNAME, ?S_SOA,
?S_MB, ?S_MG, ?S_MR, ?S_NULL,
?S_WKS, ?S_HINFO, ?S_TXT, ?S_SRV, ?S_NAPTR, ?S_SPF,
?S_UINFO, ?S_UID, ?S_GID]).
%% This function and inet_db:getbyname/2 must look up names
%% in the same manner, but not from the same places.
%%
%% Assuming search path, i.e return value from inet_db:get_searchlist()
%% to be ["dom1", "dom2"]:
%%
%% Old behaviour (not this code but the previous version):
%% * For Name = "foo"
%% Name = "foo." try "foo.dom1", "foo.dom2" at normal nameservers
%% * For Name = "foo.bar"
%% Name = "foo.bar." try "foo.bar" at normal then alt. nameservers
%% then try "foo.bar.dom1", "foo.bar.dom2"
%% at normal nameservers
%%
%% New behaviour (this code), honoring the old behaviour but
%% doing better for absolute names:
%% * For Name = "foo" try "foo.dom1", "foo.dom2" at normal nameservers
%% * For Name = "foo.bar" try "foo.bar" at normal then alt. nameservers
%% then try "foo.bar.dom1", "foo.bar.dom2"
%% at normal nameservers
%% * For Name = "foo." try "foo" at normal then alt. nameservers
%% * For Name = "foo.bar." try "foo.bar" at normal then alt. nameservers
%%
%%
%% FIXME This is probably how it should be done:
%% Common behaviour (Solaris resolver) is:
%% * For Name = "foo." try "foo"
%% * For Name = "foo.bar." try "foo.bar"
%% * For Name = "foo" try "foo.dom1", "foo.dom2", "foo"
%% * For Name = "foo.bar" try "foo.bar.dom1", "foo.bar.dom2", "foo.bar"
%% That is to try Name as it is as a last resort if it is not absolute.
%%
res_getbyname(Name, Type, Timer) ->
{EmbeddedDots, TrailingDot} = inet_parse:dots(Name),
Dot = if TrailingDot -> ""; true -> "." end,
if TrailingDot ->
res_getby_query(Name, Type, Timer);
EmbeddedDots =:= 0 ->
res_getby_search(Name, Dot,
inet_db:get_searchlist(),
nxdomain, Type, Timer);
true ->
case res_getby_query(Name, Type, Timer) of
{error,_Reason}=Error ->
res_getby_search(Name, Dot,
inet_db:get_searchlist(),
Error, Type, Timer);
Other -> Other
end
end.
res_getby_search(Name, Dot, [Dom | Ds], _Reason, Type, Timer) ->
case res_getby_query(Name++Dot++Dom, Type, Timer,
inet_db:res_option(nameservers)) of
{ok, HEnt} -> {ok, HEnt};
{error, NewReason} ->
res_getby_search(Name, Dot, Ds, NewReason, Type, Timer)
end;
res_getby_search(_Name, _, [], Reason,_,_) ->
{error, Reason}.
res_getby_query(Name, Type, Timer) ->
case res_query(Name, in, Type, [], Timer) of
{ok, Rec} ->
inet_db:res_hostent_by_domain(Name, Type, Rec);
{error,{qfmterror,_}} -> {error,einval};
{error,{Reason,_}} -> {error,Reason};
Error -> Error
end.
res_getby_query(Name, Type, Timer, NSs) ->
case res_query(Name, in, Type, [], Timer, NSs) of
{ok, Rec} ->
inet_db:res_hostent_by_domain(Name, Type, Rec);
{error,{qfmterror,_}} -> {error,einval};
{error,{Reason,_}} -> {error,Reason};
Error -> Error
end.
%% --------------------------------------------------------------------------
%% query record
%%
-record(q, {options,edns,dns}).
%% Query first nameservers list then alt_nameservers list
res_query(Name, Class, Type, Opts, Timer) ->
#q{options=#options{nameservers=NSs}}=Q =
make_query(Name, Class, Type, Opts),
case do_query(Q, NSs, Timer) of
{error,nxdomain}=Error ->
res_query_alt(Q, Error, Timer);
{error,{nxdomain,_}}=Error ->
res_query_alt(Q, Error, Timer);
{ok,#dns_rec{anlist=[]}}=Reply ->
res_query_alt(Q, Reply, Timer);
Reply -> Reply
end.
%% Query just the argument nameservers list
res_query(Name, Class, Type, Opts, Timer, NSs) ->
Q = make_query(Name, Class, Type, Opts),
do_query(Q, NSs, Timer).
res_query_alt(#q{options=#options{alt_nameservers=NSs}}=Q, Reply, Timer) ->
case NSs of
[] -> Reply;
_ ->
do_query(Q, NSs, Timer)
end.
make_query(Dname, Class, Type, Opts) ->
Options = make_options(Opts),
case Options#options.edns of
false ->
#q{options=Options,
edns=undefined,
dns=make_query(Dname, Class, Type, Options, false)};
Edns ->
#q{options=Options,
edns=make_query(Dname, Class, Type, Options, Edns),
dns=fun () ->
make_query(Dname, Class, Type, Options, false)
end}
end.
%% XXX smarter would be to always construct both queries,
%% but make the EDNS query point into the DNS query binary.
%% It is only the header ARList length that need to be changed,
%% and the OPT record appended.
make_query(Dname, Class, Type, Options, Edns) ->
Id = inet_db:res_option(next_id),
Recurse = Options#options.recurse,
ARList = case Edns of
false -> [];
_ ->
PSz = Options#options.udp_payload_size,
[#dns_rr_opt{udp_payload_size=PSz,
version=Edns}]
end,
Msg = #dns_rec{header=#dns_header{id=Id,
opcode='query',
rd=Recurse,
rcode=?NOERROR},
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}.
%% --------------------------------------------------------------------------
%% socket helpers
%%
-record(sock, {inet=undefined, inet6=undefined}).
udp_open(#sock{inet6=I}=S, {A,B,C,D,E,F,G,H}) when ?ip6(A,B,C,D,E,F,G,H) ->
case I of
undefined ->
case gen_udp:open(0, [{active,false},binary,inet6]) of
{ok,J} ->
{ok,S#sock{inet6=J}};
Error ->
Error
end;
_ ->
{ok,S}
end;
udp_open(#sock{inet=I}=S, {A,B,C,D}) when ?ip(A,B,C,D) ->
case I of
undefined ->
case gen_udp:open(0, [{active,false},binary,inet]) of
{ok,J} ->
{ok,S#sock{inet=J}};
Error ->
Error
end;
_ ->
{ok,S}
end.
udp_connect(#sock{inet6=I}, {A,B,C,D,E,F,G,H}=IP, Port)
when ?ip6(A,B,C,D,E,F,G,H), ?port(Port) ->
gen_udp:connect(I, IP, Port);
udp_connect(#sock{inet=I}, {A,B,C,D}=IP, Port)
when ?ip(A,B,C,D) ->
gen_udp:connect(I, IP, Port).
udp_send(#sock{inet6=I}, {A,B,C,D,E,F,G,H}=IP, Port, Buffer)
when ?ip6(A,B,C,D,E,F,G,H), ?port(Port) ->
gen_udp:send(I, IP, Port, Buffer);
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, Decode)
when ?ip6(A,B,C,D,E,F,G,H), ?port(Port) ->
do_udp_recv(I, IP, Port, Timeout, Decode, time_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(I, IP, Port, Timeout, Decode, time_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 = time_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.
udp_close(#sock{inet=I,inet6=I6}) ->
if I =/= undefined -> gen_udp:close(I); true -> ok end,
if I6 =/= undefined -> gen_udp:close(I6); true -> ok end,
ok.
%%
%% Send a query to the nameserver and return a reply
%% We first use socket server then we add the udp version
%%
%% Algorithm: (from manual page for dig)
%% for i = 0 to retry - 1
%% for j = 1 to num_servers
%% send_query
%% wait((time * (2**i)) / num_servers)
%% 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};
do_query(#q{options=#options{retry=Retry}}=Q, NSs, Timer) ->
query_retries(Q, NSs, Timer, Retry, 0, #sock{}).
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) ->
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) ->
{S,{noanswer,ErrNSs}};
query_nss(#q{edns=undefined}=Q, NSs, Timer, Retry, I, S, ErrNSs) ->
query_nss_dns(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),
case Res of
timeout -> {S,{error,timeout}}; % Bailout timeout
{ok,_} -> Reply;
{error,{nxdomain,_}} -> Reply;
{error,{E,_}} when E =:= qfmterror; E =:= notimp; E =:= servfail;
E =:= badvers ->
query_nss_dns(Q, NSs0, Timer, Retry, I, S, ErrNSs);
{error,E} when E =:= fmt; E =:= enetunreach; E =:= econnrefused ->
query_nss(Q, NSs, Timer, Retry, I, S, [NS|ErrNSs]);
_Error ->
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) ->
#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),
case Res of
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 ->
query_nss(Q, NSs, Timer, Retry, I, S, [NS|ErrNSs]);
_Error ->
query_nss(Q, NSs, Timer, Retry, I, S, ErrNSs)
end.
query_ns(S0, Id, 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)};
false ->
case udp_open(S0, IP) of
{ok,S} ->
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, 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]),
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;
E3 ->
?verbose(Verbose, "UDP send failed: ~p\n", [E3]),
{error,econnrefused}
end.
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
{A,B,C,D} when ?ip(A,B,C,D) -> inet;
{A,B,C,D,E,F,G,H} when ?ip6(A,B,C,D,E,F,G,H) -> inet6
end,
try gen_tcp:connect(IP, Port,
[{active,false},{packet,2},binary,Family],
Timeout) of
{ok, S} ->
case gen_tcp:send(S, Buffer) of
ok ->
case gen_tcp:recv(S, 0, Timeout) of
{ok, Answer} ->
gen_tcp:close(S),
case decode_answer(Answer, Id, Verbose) of
{ok, _} = OK -> OK;
{error, badid} -> {error, servfail};
Error -> Error
end;
Error ->
gen_tcp:close(S),
?verbose(Verbose, "TCP server recv error: ~p\n",
[Error]),
Error
end;
Error ->
gen_tcp:close(S),
?verbose(Verbose, "TCP server send error: ~p\n",
[Error]),
Error
end;
Error ->
?verbose(Verbose, "TCP server error: ~p\n", [Error]),
Error
catch
_:_ -> {error, einval}
end.
decode_answer(Answer, Id, Verbose) ->
case inet_dns:decode(Answer) of
{ok, Msg} ->
?verbose(Verbose, "Got reply: ~p~n", [dns_msg(Msg)]),
E = case lists:keyfind(dns_rr_opt, 1, Msg#dns_rec.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;
?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}}
end;
Error ->
?verbose(Verbose, "Got reply: ~p~n", [Error]),
Error
end.
%%
%% Transform domain name or address
%% 1. "a.b.c" =>
%% "a.b.c"
%% 2. "1.2.3.4" =>
%% "4.3.2.1.IN-ADDR.ARPA"
%% 3. "4321:0:1:2:3:4:567:89ab" =>
%% "b.a.9.8.7.6.5.0.4.0.0.0.3.0.0.0.2.0.0.0.1.0.0.0.0.0.0.1.2.3.4.IP6.ARPA"
%% 4. {1,2,3,4} => as 2.
%% 5. {1,2,3,4,5,6,7,8} => as 3.
%%
nsdname({A,B,C,D}) ->
{ok, dn_in_addr_arpa(A,B,C,D)};
nsdname({A,B,C,D,E,F,G,H}) ->
{ok, dn_ip6_int(A,B,C,D,E,F,G,H)};
nsdname(Name) when is_list(Name) ->
case inet_parse:visible_string(Name) of
true ->
case inet_parse:address(Name) of
{ok, Addr} ->
nsdname(Addr);
_ ->
{ok, Name}
end;
_ -> {error, formerr}
end;
nsdname(Name) when is_atom(Name) ->
nsdname(atom_to_list(Name));
nsdname(_) -> {error, formerr}.
dn_in_addr_arpa(A,B,C,D) ->
integer_to_list(D) ++
("." ++ integer_to_list(C) ++
("." ++ integer_to_list(B) ++
("." ++ integer_to_list(A) ++ ".IN-ADDR.ARPA"))).
dn_ip6_int(A,B,C,D,E,F,G,H) ->
dnib(H) ++
(dnib(G) ++
(dnib(F) ++
(dnib(E) ++
(dnib(D) ++
(dnib(C) ++
(dnib(B) ++
(dnib(A) ++ "IP6.ARPA"))))))).
-compile({inline, [dnib/1, dnib/3]}).
dnib(X) ->
L = erlang:integer_to_list(X, 16),
dnib(4-length(L), L, []).
%%
dnib(0, [], Acc) -> Acc;
dnib(0, [C|Cs], Acc) ->
dnib(0, Cs, [C,$.|Acc]);
dnib(N, Cs, Acc) ->
dnib(N-1, Cs, [$0,$.|Acc]).
dns_msg([]) -> [];
dns_msg([{Field,Msg}|Fields]) ->
[{Field,dns_msg(Msg)}|dns_msg(Fields)];
dns_msg([Msg|Msgs]) ->
[dns_msg(Msg)|dns_msg(Msgs)];
dns_msg(Msg) ->
case inet_dns:record_type(Msg) of
undefined -> Msg;
Type ->
Fields = inet_dns:Type(Msg),
{Type,dns_msg(Fields)}
end.
-compile({inline, [now_ms/2]}).
now_ms(Int1, Int0) ->
Int1 - Int0.
-compile({inline, [time_now/0]}).
time_now() ->
erlang:monotonic_time(1000).
