File 5771-Implement-DNS-LOC-record-RFC-1876.patch of Package erlang

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File 5771-Implement-DNS-LOC-record-RFC-1876.patch of Package erlang (Revision f08c7ff65135b092146ca407088fbaae)

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From 73810a2c13bd3abd2a7e096ce84ac48d6cbb0b81 Mon Sep 17 00:00:00 2001
From: Raimo Niskanen <raimo@erlang.org>
Date: Sat, 4 Mar 2023 12:21:38 +0100
Subject: [PATCH] Implement DNS LOC record (RFC 1876)

The record data Erlang representation is chosen to
be similar to the Master File Format described in RFC section 3,
i.e latitude and longitude in degrees, and altitude, size and precision
in meters; all as floating point values.

Encoding also supports integers with latitude and longitude
in thounsands of an arc second, and alitude, size and precision
in centimeters, as the RDATA format in RFC section 2.

Encoding of size and precision encodes the smallest encoding
value not less than the input value; e.g 100 encodes as 100,
4711 encodes as 5000, and 90001 encodes as 100000.
---
 lib/kernel/src/inet_dns.erl                   | 91 ++++++++++++++++++-
 lib/kernel/src/inet_dns.hrl                   |  6 +-
 lib/kernel/test/inet_res_SUITE.erl            |  5 +-
 .../inet_res_SUITE_data/otptest/otptest.zone  |  3 +
 4 files changed, 102 insertions(+), 3 deletions(-)

diff --git a/lib/kernel/src/inet_dns.erl b/lib/kernel/src/inet_dns.erl
index c236dfd0d6..7867c55501 100644
--- a/lib/kernel/src/inet_dns.erl
+++ b/lib/kernel/src/inet_dns.erl
@@ -49,6 +49,7 @@
 	 make_dns_query/2, make_dns_query/3]).
 -include("inet_dns_record_adts.hrl").
 
+
 %% Function merge of #dns_rr{} and #dns_rr_opt{}
 %%
 
@@ -112,6 +113,10 @@ lists_member(H, [H|_]) -> true;
 lists_member(H, [_|T]) -> lists_member(H, T).
 
 
+-define(in_range(Low, X, High), ((Low =< (X)) andalso ((X) =< High))).
+-define(is_decimal(X), (?in_range(0, (X), 9))).
+
+
 %% must match a clause in inet_res:query_nss_e?dns
 -define(DECODE_ERROR, formerr).
 
@@ -360,6 +365,7 @@ decode_type(Type) ->
 	?T_MX -> ?S_MX;
 	?T_TXT -> ?S_TXT;
 	?T_AAAA -> ?S_AAAA;
+	?T_LOC -> ?S_LOC;
 	?T_SRV -> ?S_SRV;
 	?T_NAPTR -> ?S_NAPTR;
 	?T_OPT -> ?S_OPT;
@@ -401,6 +407,7 @@ encode_type(Type) ->
 	?S_MX -> ?T_MX;
 	?S_TXT -> ?T_TXT;
 	?S_AAAA -> ?T_AAAA;
+	?S_LOC -> ?T_LOC;
 	?S_SRV -> ?T_SRV;
 	?S_NAPTR -> ?T_NAPTR;
 	?S_OPT -> ?T_OPT;
@@ -539,6 +546,21 @@ decode_data(Data, ?S_MX, Buffer) ->
        Data,
        <<Prio:16,Dom/binary>>,
        {Prio,decode_domain(Dom, Buffer)});
+decode_data(Data, ?S_LOC, _) ->
+    ?MATCH_ELSE_DECODE_ERROR(
+       Data,
+       <<Version:8, SizeBase:4, SizeExp:4,
+         HorizPreBase:4, HorizPreExp:4, VertPreBase:4, VertPreExp:4,
+         Latitude:32, Longitude:32, Altitude:32>>,
+       ((Version =:= 0) andalso
+        ?is_decimal(SizeBase) andalso ?is_decimal(SizeExp) andalso
+        ?is_decimal(HorizPreBase) andalso ?is_decimal(HorizPreExp) andalso
+        ?is_decimal(VertPreBase) andalso ?is_decimal(VertPreExp)),
+       {{decode_loc_angle(Latitude), decode_loc_angle(Longitude)},
+        decode_loc_altitude(Altitude),
+        decode_loc_size(SizeBase, SizeExp),
+        {decode_loc_size(HorizPreBase, HorizPreExp),
+         decode_loc_size(VertPreBase, VertPreExp)}});
 decode_data(Data, ?S_SRV, Buffer) ->
     ?MATCH_ELSE_DECODE_ERROR(
        Data,
@@ -735,6 +757,25 @@ encode_data(Comp, Pos, ?S_MINFO, Data) ->
 encode_data(Comp, Pos, ?S_MX, Data) ->
     {Pref,Exch} = Data,
     encode_name(<<Pref:16>>, Comp, Pos+2, Exch);
+encode_data(Comp, _, ?S_LOC, Data) ->
+    %% Similar to the Master File Format in section 3 of RFC 1876
+    case Data of
+        {{Latitude, Longitude}, Altitude, Size, {HorizPre, VertPre}} ->
+            ok;
+        {{Latitude, Longitude}, Altitude, Size} ->
+            HorizPre = 10_000_00, VertPre = 10_00,
+            ok;
+        {{Latitude, Longitude}, Altitude} ->
+            Size = 1_00, HorizPre = 10_000_00, VertPre = 10_00,
+            ok
+    end,
+    Version = 0,
+    {<<Version:8, (encode_loc_size(Size))/binary,
+       (encode_loc_size(HorizPre))/binary, (encode_loc_size(VertPre))/binary,
+       (encode_loc_angle(Latitude)):32,
+       (encode_loc_angle(Longitude)):32,
+       (encode_loc_altitude(Altitude)):32>>,
+     Comp};
 encode_data(Comp, Pos, ?S_SRV, Data) ->
     {Prio,Weight,Port,Target} = Data,
     encode_name(<<Prio:16,Weight:16,Port:16>>, Comp, Pos+(2+2+2), Target);
@@ -854,3 +895,51 @@ encode_labels(Bin, Comp0, Pos, [L|Ls]=Labels)
 	    %% Name compression - point to already encoded name
 	    {<<Bin/binary,3:2,Ptr:14>>,Comp0}
     end.
+
+
+decode_loc_angle(X) ->
+    (X - 16#8000_0000) / 3600_000.
+
+encode_loc_angle(X) when is_float(X) ->
+    %% Degrees (1/360 of a turn)
+    encode_loc_angle(round(X * 3600_000));
+encode_loc_angle(X)
+  when is_integer(X), -16#8000_0000 =< X, X =< 16#7FFF_FFFF ->
+    %% 1/1000:s of arc second
+    X + 16#8000_0000.  % Zero is encoded as 2^31
+
+
+decode_loc_altitude(X) ->
+    (X - 100_000_00) / 100.
+
+encode_loc_altitude(X) when is_float(X) ->
+    %% Meters
+    encode_loc_altitude(round(X * 100));
+encode_loc_altitude(X)
+  when is_integer(X), -100_000_00 =< X, X =< 16#FFFF_FFFF - 100_000_00 ->
+    %% Centimeters above a base level 100_000 m below
+    %% the GPS reference spheroid [DoD WGS-1984]
+    X + 100_000_00.
+
+
+decode_loc_size(Base, Exponent) ->
+    round(Base * math:pow(10, Exponent)) / 100.
+
+%% Return the smallest encoded value >= X;
+%% a bit like ceil(X) of encoded values
+%%
+encode_loc_size(X) when is_float(X) ->
+    %% Meters
+    encode_loc_size(round(X * 100));
+encode_loc_size(0) ->
+    0;
+encode_loc_size(X)
+  when is_integer(X), 0 =< X, X =< 9000_000_000 ->
+    %% Centimeters, to be encoded as Digit * 10^Exponent
+    %% with both Digit and Exponent in 0..9,
+    %% limiting the range to 0..9e9
+    %%
+    Exponent = floor(math:log10((X - 0.05) / 0.9)),
+    Multiplier = round(math:pow(10, Exponent)),
+    Base = (X + Multiplier - 1) div Multiplier,
+    <<Base:4, Exponent:4>>.
diff --git a/lib/kernel/src/inet_dns.hrl b/lib/kernel/src/inet_dns.hrl
index 5288c570b2..52b38b9ad1 100644
--- a/lib/kernel/src/inet_dns.hrl
+++ b/lib/kernel/src/inet_dns.hrl
@@ -72,6 +72,8 @@
 -define(T_MX,		15).		%% mail routing information
 -define(T_TXT,		16).		%% text strings
 -define(T_AAAA,         28).            %% ipv6 address
+%% LOC (RFC 1876)
+-define(T_LOC,          29).            %% location information
 %% SRV (RFC 2052)
 -define(T_SRV,          33).            %% services
 %% NAPTR (RFC 2915)
@@ -114,6 +116,8 @@
 -define(S_MX,		mx).		%% mail routing information
 -define(S_TXT,		txt).		%% text strings
 -define(S_AAAA,         aaaa).          %% ipv6 address
+%% LOC (RFC 1876)
+-define(S_LOC,          loc).           %% location information
 %% SRV (RFC 2052)
 -define(S_SRV,          srv).           %% services
 %% NAPTR (RFC 2915)
diff --git a/lib/kernel/test/inet_res_SUITE.erl b/lib/kernel/test/inet_res_SUITE.erl
index 5adce7156e..ac147551f2 100644
--- a/lib/kernel/test/inet_res_SUITE.erl
+++ b/lib/kernel/test/inet_res_SUITE.erl
@@ -886,6 +886,9 @@ resolve(Config) when is_list(Config) ->
 	 {ptr,"c.1.0.0.0.0.f.7."++RDomain6,[{ptr,Name}],undefined},
 	 {hinfo,Name,[{hinfo,{"BEAM","Erlang/OTP"}}],undefined},
 	 {mx,RDomain4,[{mx,{10,"mx."++Domain}}],undefined},
+         {loc,"loc."++Name,
+          [{loc,{{42.0625,13.125},17.0,100.0,{10000.0,10.0}}}],
+          undefined},
 	 {srv,"_srv._tcp."++Name,[{srv,{10,3,4711,Name}}],undefined},
 	 {naptr,"naptr."++Name,
 	  [{naptr,{10,5,"s","http","","_srv._tcp."++Name}}],
diff --git a/lib/kernel/test/inet_res_SUITE_data/otptest/otptest.zone b/lib/kernel/test/inet_res_SUITE_data/otptest/otptest.zone
index 9e4a3513f8..98b195fd97 100644
--- a/lib/kernel/test/inet_res_SUITE_data/otptest/otptest.zone
+++ b/lib/kernel/test/inet_res_SUITE_data/otptest/otptest.zone
@@ -42,6 +42,9 @@ wks.resolve	IN WKS		127.0.0.28 TCP ( telnet smtp )
 resolve		IN HINFO	"BEAM" "Erlang/OTP"
 ns.resolve	IN NS		resolve
 mx.resolve	IN MX	10	resolve
+;; The LOC latitude and longitude is chosen to have an exact
+;; decimal degrees floating point representation
+loc.resolve     IN LOC          42 3 45 N 13 7 30 E 17m 100m 10000m 10m
 _srv._tcp.resolve IN SRV	10 3 4711 resolve
 naptr.resolve	IN NAPTR	10 5 "S" "HTTP" "" _srv._tcp.resolve
 txt.resolve	IN TXT		"Hej " "du " "glade "
-- 
2.35.3

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