File 0366-Rewrite-cname-lookups.patch of Package erlang
From 8dd980a138c201e7ee2b099c3bbda7f470c2986a Mon Sep 17 00:00:00 2001
From: Raimo Niskanen <raimo@erlang.org>
Date: Fri, 18 Jun 2021 18:35:03 +0200
Subject: [PATCH 6/8] Rewrite cname lookups
---
lib/kernel/src/inet_db.erl | 284 +++++++++++++++---------------------
lib/kernel/src/inet_res.erl | 167 ++++++++++++---------
2 files changed, 211 insertions(+), 240 deletions(-)
diff --git a/lib/kernel/src/inet_db.erl b/lib/kernel/src/inet_db.erl
index 0a749030ef..4644bea344 100644
--- a/lib/kernel/src/inet_db.erl
+++ b/lib/kernel/src/inet_db.erl
@@ -67,8 +67,8 @@
-export([res_option/1, res_option/2, res_check_option/2]).
-export([socks_option/1]).
-export([getbyname/2, get_searchlist/0]).
--export([gethostbyaddr/1]).
--export([res_gethostbyaddr/2,res_hostent_by_domain/3]).
+-export([gethostbyaddr/2]).
+-export([res_gethostbyaddr/3,res_hostent_by_domain/3]).
-export([res_update_conf/0, res_update_hosts/0]).
%% inet help functions
-export([tolower/1, eq_domains/2]).
@@ -651,6 +651,34 @@ get_searchlist() ->
end.
+%%
+%% hostent_by_domain (cache version)
+%%
+hostent_by_domain(Domain, Type) ->
+ ?dbg("hostent_by_domain: ~p~n", [Domain]),
+ case resolve_cnames(stripdot(Domain), Type, fun lookup_cache_data/2) of
+ {error, _} = Error ->
+ Error;
+ {D, Addrs, Aliases} ->
+ {ok, make_hostent(D, Addrs, Aliases, Type)}
+ end.
+
+%%
+%% hostent_by_domain (newly resolved version)
+%% match data field directly and cache RRs.
+%%
+res_hostent_by_domain(Domain, Type, Rec) ->
+ RRs = res_filter_rrs(Type, Rec#dns_rec.anlist),
+ ?dbg("res_hostent_by_domain: ~p - ~p~n", [Domain, RRs]),
+ LookupFun = res_lookup_fun(RRs),
+ case resolve_cnames(stripdot(Domain), Type, LookupFun) of
+ {error, _} = Error ->
+ Error;
+ {D, Addrs, Aliases} ->
+ res_cache_answer(RRs),
+ {ok, make_hostent(D, Addrs, Aliases, Type)}
+ end.
+
make_hostent(Name, Addrs, Aliases, ?S_A) ->
#hostent {
h_name = Name,
@@ -677,181 +705,117 @@ make_hostent(Name, Datas, Aliases, Type) ->
h_aliases = Aliases
}.
-hostent_by_domain(Domain, Type) ->
- ?dbg("hostent_by_domain: ~p~n", [Domain]),
- hostent_by_domain(stripdot(Domain), [], [], Type).
-
-hostent_by_domain(Domain, Aliases, LAliases, Type) ->
- case lookup_type(Domain, Type) of
- [] ->
- case lookup_cname(Domain) of
- [] ->
- {error, nxdomain};
- [CName | _] ->
- LDomain = tolower(Domain),
- case lists:member(CName, [LDomain | LAliases]) of
- true ->
- {error, nxdomain};
- false ->
- hostent_by_domain(CName, [Domain | Aliases],
- [LDomain | LAliases], Type)
- end
- end;
- Addrs ->
- {ok, make_hostent(Domain, Addrs, Aliases, Type)}
- end.
-%% lookup canonical name
-lookup_cname(Domain) ->
- lookup_type(Domain, ?S_CNAME).
-%% lookup address record
-lookup_type(Domain, Type) ->
- [R#dns_rr.data || R <- lookup_rr(Domain, in, Type) ].
-
-%% lookup resource record
-lookup_rr(Domain, Class, Type) ->
- match_rr(dns_rr_match(tolower(Domain), Class, Type)).
-
-%%
-%% hostent_by_domain (newly resolved version)
-%% match data field directly and cache RRs.
-%%
-res_hostent_by_domain(Domain, Type, Rec) ->
- RRs =
- [RR#dns_rr{bm = tolower(N)} ||
- #dns_rr{
- domain = N,
- class = in,
- type = T} = RR <- Rec#dns_rec.anlist,
- T =:= Type orelse T =:= ?S_CNAME],
- res_cache_answer(RRs),
- ?dbg("res_hostent_by_domain: ~p - ~p~n", [Domain, RRs]),
- Domain_1 = stripdot(Domain),
- res_hostent_by_domain(Domain_1, tolower(Domain_1), [], [], Type, RRs).
-
-res_hostent_by_domain(Domain, LcDomain, Aliases, LcAliases, Type, RRs) ->
- case res_lookup_type(LcDomain, Type, RRs) of
- [] ->
- case res_lookup_type(LcDomain, ?S_CNAME, RRs) of
- [] ->
- {error, nxdomain};
- [CName | _] ->
- LcCName = tolower(CName),
- case lists:member(LcCName, [LcDomain | LcAliases]) of
- true ->
- %% CNAME loop
- {error, nxdomain};
- false ->
- res_hostent_by_domain(
- CName, LcCName,
- [Domain | Aliases], [LcDomain | LcAliases],
- Type, RRs)
- end
- end;
- Addrs ->
- {ok, make_hostent(Domain, Addrs, Aliases, Type)}
+res_filter_rrs(Type, RRs) ->
+ [RR#dns_rr{bm = tolower(N)} ||
+ #dns_rr{
+ domain = N,
+ class = in,
+ type = T} = RR <- RRs,
+ T =:= Type orelse T =:= ?S_CNAME].
+
+res_lookup_fun(RRs) ->
+ fun (LcDomain, Type) ->
+ [Data
+ || #dns_rr{bm = LcD, type = T, data = Data}
+ <- RRs,
+ LcD =:= LcDomain,
+ T =:= Type]
end.
-%% newly resolved lookup address record
-res_lookup_type(LcDomain, Type, RRs) ->
- [R#dns_rr.data || R <- RRs,
- R#dns_rr.bm =:= LcDomain,
- R#dns_rr.type =:= Type].
-%%
-%% gethostbyaddr (cache version)
-%% match data field directly
-%%
-gethostbyaddr(IP) ->
- case dnip(IP) of
- {ok, {IP1, HType, HLen, DnIP}} ->
- gethostbyaddr(IP1, HType, HLen, DnIP, []);
- Error -> Error
- end.
+resolve_cnames(Domain, Type, LookupFun) ->
+ resolve_cnames(Domain, Type, LookupFun, tolower(Domain), [], []).
-gethostbyaddr(IP, HType, HLen, DnIP, DnIPs) ->
- MatchPtrRR = dns_rr_match(DnIP, in, ptr),
- case match_rr(MatchPtrRR) of
+resolve_cnames(Domain, Type, LookupFun, LcDomain, Aliases, LcAliases) ->
+ case LookupFun(LcDomain, Type) of
[] ->
- case lookup_cname(DnIP) of
- [#dns_rr{data = DnIP_1} | _] ->
- DnIPs_1 = [DnIP | DnIPs],
- %% CNAME loop protection
- case lists:member(DnIP_1, DnIPs_1) of
+ case LookupFun(LcDomain, ?S_CNAME) of
+ [] ->
+ %% Did not find neither Type nor CNAME record
+ {error, nxdomain};
+ [CName] ->
+ LcCname = tolower(CName),
+ case lists:member(LcCname, [LcDomain | LcAliases]) of
true ->
+ %% CNAME loop
{error, nxdomain};
false ->
- gethostbyaddr(IP, HType, HLen, DnIP_1, DnIPs_1)
+ %% Repeat with the (more) canonical domain name
+ resolve_cnames(
+ CName, Type, LookupFun, LcCname,
+ [Domain | Aliases], [LcDomain, LcAliases])
end;
- CNames when is_list(CNames) ->
+ [_ | _] = _CNames ->
+ ?dbg("resolve_cnames duplicate cnames=~p~n", [_CNames]),
{error, nxdomain}
end;
- RRs when is_list(RRs) ->
- ent_gethostbyaddr(RRs, IP, HType, HLen)
+ [_ | _] = Results ->
+ {Domain, Results, Aliases}
+ end.
+
+
+%%
+%% gethostbyaddr (cache version)
+%% match data field directly
+%%
+gethostbyaddr(Domain, IP) ->
+ ?dbg("gethostbyaddr: ~p~n", [IP]),
+ case resolve_cnames(Domain, ?S_PTR, fun lookup_cache_data/2) of
+ {error, _} = Error ->
+ Error;
+ {_D, Domains, _Aliases} ->
+ ent_gethostbyaddr(Domains, IP)
end.
%%
%% res_gethostbyaddr (newly resolved version)
%% match data field directly and cache RRs.
%%
-res_gethostbyaddr(IP, Rec) ->
- {ok, {IP1, HType, HLen}} = dnt(IP),
- RRs =
- [RR#dns_rr{bm = tolower(N)} ||
- #dns_rr{
- domain = N,
- class = in,
- type = T} = RR <- Rec#dns_rec.anlist,
- T =:= ?S_PTR orelse T =:= ?S_CNAME],
- res_cache_answer(RRs),
- case [RR || #dns_rr{type = ?S_PTR} = RR <- RRs] of
- [] ->
- {error, nxdomain};
- PtrRRs ->
- ent_gethostbyaddr(PtrRRs, IP1, HType, HLen)
+res_gethostbyaddr(Name, IP, Rec) ->
+ RRs = res_filter_rrs(?S_PTR, Rec#dns_rec.anlist),
+ ?dbg("res_gethostbyaddr: ~p - ~p~n", [IP, RRs]),
+ LookupFun = res_lookup_fun(RRs),
+ case resolve_cnames(Name, ?S_PTR, LookupFun) of
+ {error, _} = Error ->
+ Error;
+ {_D, Domains, _Aliases} ->
+ case ent_gethostbyaddr(Domains, IP) of
+ {ok, _HEnt} = Result ->
+ res_cache_answer(RRs),
+ Result;
+ {error, _} = Error ->
+ Error
+ end
end.
-ent_gethostbyaddr([RR|RRs], IP, AddrType, Length) ->
- %% debug
- if RRs =/= [] ->
- ?dbg("gethostbyaddr found extra=~p~n", [RRs]);
- true -> ok
- end,
- Domain = RR#dns_rr.data,
+ent_gethostbyaddr([Domain], IP) ->
+ {IP_1, AddrType, Length} = norm_ip(IP),
H =
#hostent{
h_name = Domain,
- %% Since a PTR record should point to
- %% the canonical name, this Domain should
- %% have no CNAME record, so is this really reasonable?
- h_aliases = lookup_cname(Domain),
- h_addr_list = [IP],
+ h_aliases = [],
+ h_addr_list = [IP_1],
h_addrtype = AddrType,
h_length = Length },
- {ok, H}.
+ {ok, H};
+ent_gethostbyaddr([_ | _] = _Domains, _IP) ->
+ ?dbg("gethostbyaddr duplicate domains=~p~n", [_Domains]),
+ {error, nxdomain}.
-
-dnip(IP) ->
- case dnt(IP) of
- {ok,{IP1 = {A,B,C,D}, inet, HLen}} ->
- {ok,{IP1, inet, HLen, dn_in_addr_arpa(A,B,C,D)}};
- {ok,{IP1 = {A,B,C,D,E,F,G,H}, inet6, HLen}} ->
- {ok,{IP1, inet6, HLen, dn_ip6_int(A,B,C,D,E,F,G,H)}};
- _ ->
- {error, formerr}
- end.
+%% Normalize an IPv4-compatible IPv6 address
+%% into a plain IPv4 address
+%%
+norm_ip(IP) when tuple_size(IP) =:= 4 ->
+ {IP, inet, 4};
+norm_ip({0,0,0,0,0,16#ffff,G,H}) ->
+ A = G bsr 8, B = G band 16#ff, C = H bsr 8, D = H band 16#ff,
+ {{A,B,C,D}, inet, 4};
+norm_ip(IP) when tuple_size(IP) =:= 8 ->
+ {IP, inet6, 16}.
-dnt(IP = {A,B,C,D}) when ?ip(A,B,C,D) ->
- {ok, {IP, inet, 4}};
-dnt({0,0,0,0,0,16#ffff,G,H}) when is_integer(G+H) ->
- A = G div 256, B = G rem 256, C = H div 256, D = H rem 256,
- {ok, {{A,B,C,D}, inet, 4}};
-dnt(IP = {A,B,C,D,E,F,G,H}) when ?ip6(A,B,C,D,E,F,G,H) ->
- {ok, {IP, inet6, 16}};
-dnt(_) ->
- {error, formerr}.
%%
%% Register socket Modules
@@ -1758,6 +1722,11 @@ dns_rr_match(LcDomain, Class, Type, Data) ->
cnt = '_', tm = '_', ttl = '_', bm = LcDomain, func = '_'}.
+lookup_cache_data(LcDomain, Type) ->
+ [Data
+ || #dns_rr{data = Data}
+ <- match_rr(dns_rr_match(LcDomain, in, Type))].
+
%% We are simultaneously updating the table from all clients
%% and the server, so we might get duplicate recource records
%% in the table, i.e identical domain, class, type and data.
@@ -1892,25 +1861,6 @@ eq_domains(As, Bs) when is_list(As), is_list(Bs) ->
false.
-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.int".
-
-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".
-
-dnib(X) ->
- [hex(X), $., hex(X bsr 4), $., hex(X bsr 8), $., hex(X bsr 12), $.].
-
-hex(X) ->
- X4 = (X band 16#f),
- if X4 < 10 -> X4 + $0;
- true -> (X4-10) + $a
- end.
-
%% Strip trailing dot, do not produce garbage unless necessary.
%%
stripdot(Name) ->
diff --git a/lib/kernel/src/inet_res.erl b/lib/kernel/src/inet_res.erl
index e238cfd2a1..f5ab7e6a23 100644
--- a/lib/kernel/src/inet_res.erl
+++ b/lib/kernel/src/inet_res.erl
@@ -355,40 +355,37 @@ gethostbyaddr(IP,Timeout) ->
_ = 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;
-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) ->
+gethostbyaddr_tm(Addr, Timer) when is_atom(Addr) ->
+ gethostbyaddr_tm(atom_to_list(Addr), Timer);
+gethostbyaddr_tm(Addr, Timer) when is_list(Addr) ->
case inet_parse:address(Addr) of
- {ok, IP} -> gethostbyaddr_tm(IP,Timer);
+ {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, ?S_PTR, [], Timer) of
- {ok, Rec} ->
- inet_db:res_gethostbyaddr(IP, Rec);
- {error,{qfmterror,_}} -> {error,einval};
- {error,{Reason,_}} -> {error,Reason};
- Error ->
- Error
+gethostbyaddr_tm(IP, Timer) ->
+ case dn_ip(IP) of
+ {error, _} = Error ->
+ Error;
+ Name ->
+ %% Try cached first
+ inet_db:res_update_conf(),
+ case inet_db:gethostbyaddr(Name, IP) of
+ {ok, _HEnt} = Result ->
+ Result;
+ {error, nxdomain} ->
+ %% Do a resolver lookup
+ case res_query(Name, in, ?S_PTR, [], Timer) of
+ {ok, Rec} ->
+ %% Process and cache DNS Record
+ inet_db:res_gethostbyaddr(Name, IP, Rec);
+ {error,{qfmterror,_}} ->
+ {error,einval};
+ {error,{Reason,_}} ->
+ {error,Reason};
+ Error ->
+ Error
+ end
+ end
end.
%% --------------------------------------------------------------------------
@@ -479,12 +476,17 @@ 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};
+ false ->
+ {error, formerr};
true ->
+ %% Try cached first
inet_db:res_update_conf(),
case inet_db:getbyname(Name, Type) of
- {ok, HEnt} -> {ok, HEnt};
- _ -> res_getbyname(Name, Type, Timer)
+ {ok, HEnt} ->
+ {ok, HEnt};
+ _ ->
+ %% Do a resolver lookup
+ res_getbyname(Name, Type, Timer)
end
end;
false ->
@@ -577,6 +579,7 @@ res_getby_search(_Name, [], Reason,_,_) ->
res_getby_query(Name, Type, Timer) ->
case res_query(Name, in, Type, [], Timer) of
{ok, Rec} ->
+ %% Process and cache DNS Record
inet_db:res_hostent_by_domain(Name, Type, Rec);
{error,{qfmterror,_}} -> {error,einval};
{error,{Reason,_}} -> {error,Reason};
@@ -586,6 +589,7 @@ res_getby_query(Name, Type, Timer) ->
res_getby_query(Name, Type, Timer, NSs) ->
case res_query(Name, in, Type, [], Timer, NSs) of
{ok, Rec} ->
+ %% Process and cache DNS Record
inet_db:res_hostent_by_domain(Name, Type, Rec);
{error,{qfmterror,_}} -> {error,einval};
{error,{Reason,_}} -> {error,Reason};
@@ -1128,59 +1132,76 @@ decode_answer_noerror(
%% 1. "a.b.c" =>
%% "a.b.c"
%% 2. "1.2.3.4" =>
-%% "4.3.2.1.IN-ADDR.ARPA"
+%% "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"
+%% "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.
+%% 6. Atom -> Recurse(String(Atom))
+%% 7. Term => {error, formerr}
%%
-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_atom(Name) ->
+ nsdname(atom_to_list(Name));
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, IP} ->
+ dn_ip(IP);
_ ->
{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, []).
+nsdname(IP) ->
+ dn_ip(IP).
+
+%% Return the domain name for a PTR lookup of
+%% the argument IP address
%%
-dnib(0, [], Acc) -> Acc;
-dnib(0, [C|Cs], Acc) ->
- dnib(0, Cs, [C,$.|Acc]);
-dnib(N, Cs, Acc) ->
- dnib(N-1, Cs, [$0,$.|Acc]).
+dn_ip({A,B,C,D}) when ?ip(A,B,C,D) ->
+ dn_ipv4([A,B,C,D], "in-addr.arpa");
+dn_ip({A,B,C,D,E,F,G,H}) when ?ip6(A,B,C,D,E,F,G,H) ->
+ dn_ipv6([A,B,C,D,E,F,G,H], "ip6.arpa");
+dn_ip(_) ->
+ {error, formerr}.
+
+dn_ipv4([], Dn) ->
+ Dn;
+dn_ipv4([A | As], Dn_0) when is_integer(A), A =< 255 ->
+ Dn = [$. | Dn_0],
+ if
+ A < 10 ->
+ dn_ipv4(As, dn_dec(A, Dn));
+ A < 100 ->
+ dn_ipv4(As, dn_dec(A div 10, dn_dec(A rem 10, Dn)));
+ true ->
+ B = A rem 100,
+ dn_ipv4(
+ As,
+ dn_dec(A div 100, dn_dec(B div 10, dn_dec(B rem 10, Dn))))
+ end.
+
+dn_ipv6([], Dn) ->
+ Dn;
+dn_ipv6([W | Ws], Dn) when is_integer(W), W =< 16#ffff ->
+ D = W band 16#f, W_1 = W bsr 4,
+ C = W_1 band 16#f, W_2 = W_1 bsr 4,
+ B = W_2 band 16#f,
+ A = W_2 bsr 4,
+ dn_ipv6(Ws, dn_hex(D, dn_hex(C, dn_hex(B, dn_hex(A, Dn))))).
+
+-compile({inline, [dn_dec/2, dn_hex/2]}).
+dn_dec(N, Tail) when is_integer(N) ->
+ [N + $0 | Tail].
+
+dn_hex(N, Tail) when is_integer(N) ->
+ if
+ N < 10 ->
+ [N + $0, $. | Tail];
+ true ->
+ [(N - 10) + $a, $. | Tail]
+end.
--
2.31.1
