File 0300-Change-inet_parse-visible_string-1-to-allow-empty-st.patch of Package erlang

From 4f7049382757e6804e317b883547ce6b346816e6 Mon Sep 17 00:00:00 2001
From: Raimo Niskanen <raimo@erlang.org>
Date: Mon, 3 Apr 2023 16:35:33 +0200
Subject: [PATCH 1/4] Change inet_parse:visible_string/1 to allow empty string

---
 lib/kernel/src/inet.erl       |  4 ++--
 lib/kernel/src/inet_db.erl    |  7 +++----
 lib/kernel/src/inet_parse.erl | 13 ++++---------
 lib/kernel/src/inet_res.erl   |  4 ++--
 4 files changed, 11 insertions(+), 17 deletions(-)

diff --git a/lib/kernel/src/inet.erl b/lib/kernel/src/inet.erl
index d836f6b367..55114ab7f9 100644
--- a/lib/kernel/src/inet.erl
+++ b/lib/kernel/src/inet.erl
@@ -1513,7 +1513,7 @@ getaddrs_tm({A,B,C,D,E,F,G,H} = IP, Fam, _) ->
 getaddrs_tm(Address, Family, Timer) when is_atom(Address) ->
     getaddrs_tm(atom_to_list(Address), Family, Timer);
 getaddrs_tm(Address, Family, Timer) ->
-    case inet_parse:visible_string(Address) of
+    case inet_parse:visible_string(Address) andalso Address =/= "" of
 	false ->
 	    {error,einval};
 	true ->
diff --git a/lib/kernel/src/inet_db.erl b/lib/kernel/src/inet_db.erl
index 408f563909..0dbfeb80ed 100644
--- a/lib/kernel/src/inet_db.erl
+++ b/lib/kernel/src/inet_db.erl
@@ -498,7 +498,7 @@ res_check_option(nameservers, NSs) ->
 res_check_option(alt_nameservers, NSs) ->
     res_check_list(NSs, fun res_check_ns/1);
 res_check_option(domain, Dom) ->
-    Dom =:= "" orelse inet_parse:visible_string(Dom);
+    inet_parse:visible_string(Dom);
 res_check_option(lookup, Methods) ->
     try lists_subtract(Methods, valid_lookup()) of
 	[] -> true;
@@ -550,7 +550,6 @@ res_check_ns({{A,B,C,D}, Port})
   when ?ip(A,B,C,D), Port band 65535 =:= Port -> true;
 res_check_ns(_) -> false.
 
-res_check_search("") -> true;
 res_check_search(Dom) -> inet_parse:visible_string(Dom).
 
 socks_option(server)  -> db_get(socks5_server);
@@ -1044,7 +1043,7 @@ handle_call(Request, From, #state{db=Db}=State) ->
 	    end;
 
 	{set_hostname, Name} ->
-	    case inet_parse:visible_string(Name) of
+	    case inet_parse:visible_string(Name) andalso Name =/= "" of
 		true ->
 		    ets:insert(Db, {hostname, Name}),
 		    {reply, ok, State};
diff --git a/lib/kernel/src/inet_parse.erl b/lib/kernel/src/inet_parse.erl
index 31d759428d..9d54d2c6bd 100644
--- a/lib/kernel/src/inet_parse.erl
+++ b/lib/kernel/src/inet_parse.erl
@@ -1,7 +1,7 @@
 %%
 %% %CopyrightBegin%
 %%
-%% Copyright Ericsson AB 1997-2021. All Rights Reserved.
+%% Copyright Ericsson AB 1997-2023. 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.
@@ -386,14 +386,9 @@ port_proto([$/ | Proto], Port) when Port =/= 0 ->
 %% Check if a String is a string with visible characters #21..#7E
 %% visible_string(String) -> Bool
 %%
-visible_string([H|T]) ->
-    is_vis1([H|T]);
-visible_string(_) ->
-    false.
-
-is_vis1([C | Cs]) when C >= 16#21, C =< 16#7e -> is_vis1(Cs);
-is_vis1([]) -> true;
-is_vis1(_) -> false.
+visible_string([C | Cs]) when C >= 16#21, C =< 16#7e -> visible_string(Cs);
+visible_string([]) -> true;
+visible_string(_) -> false.
 
 %%
 %% Check if a String is a domain name according to RFC XXX.
diff --git a/lib/kernel/src/inet_res.erl b/lib/kernel/src/inet_res.erl
index 4e7809564c..4e0888c62e 100644
--- a/lib/kernel/src/inet_res.erl
+++ b/lib/kernel/src/inet_res.erl
@@ -490,7 +490,7 @@ getbyname(Name, Type, Timeout) ->
 getbyname_tm(Name, Type, Timer) when is_list(Name) ->
     case type_p(Type) of
 	true ->
-	    case inet_parse:visible_string(Name) of
+	    case inet_parse:visible_string(Name) andalso Name =/= "" of
 		false ->
                     {error, formerr};
 		true ->
-- 
2.35.3