Merge branch 'rani/inet_gethostbyname_fixes' into ccase/r13b04_dev

* rani/inet_gethostbyname_fixes:
  inet_res_SUITE: testcase fixes for legacy DNS resolver (Solaris 8)
  inet_res: /etc/resolv.conf: use domain as default search list
  inet: delayed/avoided read of /etc/resolv.conf and /etc/hosts
  inet_gethost_native: workaround for empty result hostname on MacOS X
  inet_res_SUITE: testcase fix for empty domain name
  inet:gethostbyname improved to parse IP strings and look up own hostname

OTP-8426  The resolver routines failed to look up the own node name as
          hostname, if the OS native resolver was erroneously configured,
          bug reported by Yogish Baliga, now fixed.

          The resolver routines now tries to parse the hostname as an IP
          string as most OS resolvers do, unless the native resolver is
          used.

          The DNS resolver inet_res and file resolver inet_hosts now do not
          read OS configuration files until they are needed. Since the
          native resolver is default, in most cases they are never needed.

          The DNS resolver's automatic updating of OS configuration file
          data (/etc/resolv.conf) now uses the 'domain' keyword as default
          search domain if there is no 'search' keyword.

1 files changed, 84 insertions, 63 deletions

diff --git a/lib/kernel/src/inet.erl b/lib/kernel/src/inet.erl
index b86aa1839e..eb503235d8 100644
--- a/lib/kernel/src/inet.erl
+++ b/lib/kernel/src/inet.erl
@@ -1,19 +1,19 @@
 %%
 %% %CopyrightBegin%
-%% 
-%% Copyright Ericsson AB 1997-2009. All Rights Reserved.
-%% 
+%%
+%% Copyright Ericsson AB 1997-2010. All Rights Reserved.
+%%
 %% The contents of this file are subject to the Erlang Public License,
 %% Version 1.1, (the "License"); you may not use this file except in
 %% compliance with the License. You should have received a copy of the
 %% Erlang Public License along with this software. If not, it can be
 %% retrieved online at http://www.erlang.org/.
-%% 
+%%
 %% Software distributed under the License is distributed on an "AS IS"
 %% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
 %% the License for the specific language governing rights and limitations
 %% under the License.
-%% 
+%%
 %% %CopyrightEnd%
 %%
 -module(inet).
@@ -45,6 +45,7 @@
 %% resolve
 -export([gethostbyname/1, gethostbyname/2, gethostbyname/3, 
 	 gethostbyname_tm/3]).
+-export([gethostbyname_string/2, gethostbyname_self/2]).
 -export([gethostbyaddr/1, gethostbyaddr/2, 
 	 gethostbyaddr_tm/2]).
 
@@ -411,7 +412,17 @@ gethostbyname(Name,Family,Timeout) ->
     Res.
 
 gethostbyname_tm(Name,Family,Timer) ->
-    gethostbyname_tm(Name,Family,Timer,inet_db:res_option(lookup)).
+    Opts0 = inet_db:res_option(lookup),
+    Opts =
+	case (lists:member(native, Opts0) orelse
+	      lists:member(string, Opts0) orelse
+	      lists:member(nostring, Opts0)) of
+	    true ->
+		Opts0;
+	    false ->
+		[string|Opts0]
+	end,
+    gethostbyname_tm(Name, Family, Timer, Opts).
 
 
 -spec gethostbyaddr(Address :: string() | ip_address()) ->
@@ -850,75 +861,61 @@ getaddrs_tm(Address, Family, Timer) ->
 %%
 %% gethostbyname with option search
 %%
-gethostbyname_tm(Name, Type, Timer, [dns | Opts]) ->
-    Res = inet_res:gethostbyname_tm(Name, Type, Timer),
-    case Res of
-	{ok,_} -> Res;
-	{error,timeout} -> Res;
-	{error,formerr} -> {error,einval};
-	{error,_} -> gethostbyname_tm(Name,Type,Timer,Opts)
-    end;
-gethostbyname_tm(Name, Type, Timer, [file | Opts]) ->
-    case inet_hosts:gethostbyname(Name, Type) of
-	{error,formerr} -> {error,einval};
-	{error,_} -> gethostbyname_tm(Name,Type,Timer,Opts);
-	Result -> Result
-    end;
-gethostbyname_tm(Name, Type, Timer, [yp | Opts]) ->
+gethostbyname_tm(Name, Type, Timer, [string|_]=Opts) ->
+    Result = gethostbyname_string(Name, Type),
+    gethostbyname_tm(Name, Type, Timer, Opts, Result);
+gethostbyname_tm(Name, Type, Timer, [dns|_]=Opts) ->
+    Result = inet_res:gethostbyname_tm(Name, Type, Timer),
+    gethostbyname_tm(Name, Type, Timer, Opts, Result);
+gethostbyname_tm(Name, Type, Timer, [file|_]=Opts) ->
+    Result = inet_hosts:gethostbyname(Name, Type),
+    gethostbyname_tm(Name, Type, Timer, Opts, Result);
+gethostbyname_tm(Name, Type, Timer, [yp|_]=Opts) ->
     gethostbyname_tm_native(Name, Type, Timer, Opts);
-gethostbyname_tm(Name, Type, Timer, [nis | Opts]) ->
+gethostbyname_tm(Name, Type, Timer, [nis|_]=Opts) ->
     gethostbyname_tm_native(Name, Type, Timer, Opts);
-gethostbyname_tm(Name, Type, Timer, [nisplus | Opts]) ->
+gethostbyname_tm(Name, Type, Timer, [nisplus|_]=Opts) ->
     gethostbyname_tm_native(Name, Type, Timer, Opts);
-gethostbyname_tm(Name, Type, Timer, [wins | Opts]) ->
+gethostbyname_tm(Name, Type, Timer, [wins|_]=Opts) ->
     gethostbyname_tm_native(Name, Type, Timer, Opts);
-gethostbyname_tm(Name, Type, Timer, [native | Opts]) ->
+gethostbyname_tm(Name, Type, Timer, [native|_]=Opts) ->
     gethostbyname_tm_native(Name, Type, Timer, Opts);
-gethostbyname_tm(_, _, _, [no_default|_]) ->
-    %% If the native resolver has failed, we should not bother
-    %% to try to be smarter and parse the IP address here.
-    {error,nxdomain};
-gethostbyname_tm(Name, Type, Timer, [_ | Opts]) ->
+gethostbyname_tm(Name, Type, Timer, [_|_]=Opts) ->
     gethostbyname_tm(Name, Type, Timer, Opts);
-%% Last resort - parse the hostname as address
-gethostbyname_tm(Name, inet, _Timer, []) ->
-    case inet_parse:ipv4_address(Name) of
-	{ok,IP4} ->
-	    {ok,make_hostent(Name, [IP4], [], inet)};
-	_ ->
-	    gethostbyname_self(Name)
-    end;
-gethostbyname_tm(Name, inet6, _Timer, []) ->
-    case inet_parse:ipv6_address(Name) of
-	{ok,IP6} ->
-	    {ok,make_hostent(Name, [IP6], [], inet6)};
-	_ ->
-	    %% Even if Name is a valid IPv4 address, we can't
-	    %% assume it's correct to return it on a IPv6
-	    %% format ( {0,0,0,0,0,16#ffff,?u16(A,B),?u16(C,D)} ).
-	    %% This host might not support IPv6.
-	    gethostbyname_self(Name)
+%% Make sure we always can look up our own hostname.
+gethostbyname_tm(Name, Type, Timer, []) ->
+    Result = gethostbyname_self(Name, Type),
+    gethostbyname_tm(Name, Type, Timer, [], Result).
+
+gethostbyname_tm(Name, Type, Timer, Opts, Result) ->
+    case Result of
+	{ok,_} ->
+	    Result;
+	{error,formerr} ->
+	    {error,einval};
+	{error,_} when Opts =:= [] ->
+	    {error,nxdomain};
+	{error,_} ->
+	    gethostbyname_tm(Name, Type, Timer, tl(Opts))
     end.
 
 gethostbyname_tm_native(Name, Type, Timer, Opts) ->
     %% Fixme: add (global) timeout to gethost_native
-    case inet_gethost_native:gethostbyname(Name, Type) of
-	{error,formerr} -> {error,einval};
-	{error,timeout} -> {error,timeout};
-	{error,_} -> gethostbyname_tm(Name, Type, Timer, Opts++[no_default]);
-	Result -> Result
-    end.
+    Result = inet_gethost_native:gethostbyname(Name, Type),
+    gethostbyname_tm(Name, Type, Timer, Opts, Result).
 
-%% Make sure we always can look up our own hostname.
-gethostbyname_self(Name) ->
-    Type = case inet_db:res_option(inet6) of
-	       true -> inet6;
-	       false -> inet
-	   end,
+
+
+gethostbyname_self(Name, Type) when is_atom(Name) ->
+    gethostbyname_self(atom_to_list(Name), Type);
+gethostbyname_self(Name, Type)
+  when is_list(Name), Type =:= inet;
+       is_list(Name), Type =:= inet6 ->
     case inet_db:gethostname() of
 	Name ->
-	    {ok,make_hostent(Name, [translate_ip(loopback, Type)],
-			 [], Type)};
+	    {ok,make_hostent(Name,
+			     [translate_ip(loopback, Type)],
+			     [], Type)};
 	Self ->
 	    case inet_db:res_option(domain) of
 		"" -> {error,nxdomain};
@@ -931,7 +928,31 @@ gethostbyname_self(Name) ->
 			_ -> {error,nxdomain}
 		    end
 	    end
-    end.
+    end;
+gethostbyname_self(_, _) ->
+    {error,formerr}.
+
+gethostbyname_string(Name, Type) when is_atom(Name) ->
+    gethostbyname_string(atom_to_list(Name), Type);
+gethostbyname_string(Name, Type)
+  when is_list(Name), Type =:= inet;
+       is_list(Name), Type =:= inet6 ->
+    case
+	case Type of
+	    inet ->
+		inet_parse:ipv4_address(Name);
+	    inet6 ->
+		%% XXX should we really translate IPv4 addresses here
+		%% even if we do not know if this host can do IPv6?
+		inet_parse:ipv6_address(Name)
+	end of
+	{ok,IP} ->
+	    {ok,make_hostent(Name, [IP], [], Type)};
+	{error,einval} ->
+	    {error,nxdomain}
+    end;
+gethostbyname_string(_, _) ->
+    {error,formerr}.
 
 make_hostent(Name, Addrs, Aliases, Type) ->
     #hostent{h_name = Name,