inet: delayed/avoided read of /etc/resolv.conf and /etc/hosts

The 'file' and 'dns' lookup methods configuration files are now read and parsed at the time of the first lookup instead of at boot time when per default none of these lookup methods are used.
erlang · Feb 9, 2010 · 0377ecd · 0377ecd
1 parent a53dfdc
commit 0377ecd
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Showing 2 changed files with 69 additions and 41 deletions.
diff --git a/lib/kernel/src/inet_config.erl b/lib/kernel/src/inet_config.erl
@@ -130,21 +130,25 @@ init() ->
 	{unix,_} ->
 	    %% The Etc variable enables us to run tests with other 
 	    %% configuration files than the normal ones 
-	    Etc = case os:getenv("ERL_INET_ETC_DIR") of
-		      false -> ?DEFAULT_ETC;
-		      _EtcDir -> 
-			  _EtcDir			
-		  end,
+	    Etc =
+		case os:getenv("ERL_INET_ETC_DIR") of
+		    false ->
+			?DEFAULT_ETC;
+		    _EtcDir ->
+			_EtcDir
+		end,
 	    case inet_db:res_option(resolv_conf) of
 		undefined ->
-		    inet_db:set_resolv_conf(filename:join(Etc,
-							  ?DEFAULT_RESOLV));
+		    inet_db:res_option(
+		      resolv_conf_name,
+		      filename:join(Etc, ?DEFAULT_RESOLV));
 		_ -> ok
 	    end,
 	    case inet_db:res_option(hosts_file) of
 		undefined ->
-		    inet_db:set_hosts_file(filename:join(Etc,
-							 ?DEFAULT_HOSTS));
+		    inet_db:res_option(
+		      hosts_file_name,
+		      filename:join(Etc, ?DEFAULT_HOSTS));
 		_ -> ok
 	    end;
 	_ -> ok

diff --git a/lib/kernel/src/inet_db.erl b/lib/kernel/src/inet_db.erl
@@ -425,7 +425,9 @@ res_optname(usevc) -> res_usevc;
 res_optname(edns) -> res_edns;
 res_optname(udp_payload_size) -> res_udp_payload_size;
 res_optname(resolv_conf) -> res_resolv_conf;
+res_optname(resolv_conf_name) -> res_resolv_conf;
 res_optname(hosts_file) -> res_hosts_file;
+res_optname(hosts_file_name) -> res_hosts_file;
 res_optname(_) -> undefined.
 
 res_check_option(nameserver, NSs) -> %% Legacy
@@ -458,9 +460,15 @@ res_check_option(udp_payload_size, S) when is_integer(S), S >= 512 -> true;
 res_check_option(resolv_conf, "") -> true;
 res_check_option(resolv_conf, F) ->
     res_check_option_absfile(F);
+res_check_option(resolv_conf_name, "") -> true;
+res_check_option(resolv_conf_name, F) ->
+    res_check_option_absfile(F);
 res_check_option(hosts_file, "") -> true;
 res_check_option(hosts_file, F) ->
     res_check_option_absfile(F);
+res_check_option(hosts_file_name, "") -> true;
+res_check_option(hosts_file_name, F) ->
+    res_check_option_absfile(F);
 res_check_option(_, _) -> false.
 
 res_check_option_absfile(F) ->
@@ -503,7 +511,7 @@ res_update_hosts() ->
     res_update(res_hosts_file, res_hosts_file_tm, res_hosts_file_info,
 	       set_hosts_file_tm, fun set_hosts_file/1).
 
-res_update(Tag, TagTm, TagInfo, CallTag, SetFun) ->
+res_update(Tag, TagTm, TagInfo, TagSetTm, SetFun) ->
     case db_get(TagTm) of
 	undefined -> ok;
 	TM ->
@@ -522,12 +530,12 @@ res_update(Tag, TagTm, TagInfo, CallTag, SetFun) ->
 							 atime = undefined},
 				    case db_get(TagInfo) of
 					Finfo ->
-					    call({CallTag, Now});
+					    call({TagSetTm, Now});
 					_ ->
 					    SetFun(File)
 				    end;
 				_ ->
-				    call({CallTag, Now}),
+				    call({TagSetTm, Now}),
 				    error
 			    end
 		    end;
@@ -974,37 +982,46 @@ handle_call(Request, From, #state{db=Db}=State) ->
 		    {reply, error, State}
 	    end;
 
+	{res_set, hosts_file_name=Option, Fname} ->
+	    handle_set_file(
+	      Option, Fname, res_hosts_file_tm, res_hosts_file_info,
+	      undefined, From, State);
+	{res_set, resolv_conf_name=Option, Fname} ->
+	    handle_set_file(
+	      Option, Fname, res_resolv_conf_tm, res_resolv_conf_info,
+	      undefined, From, State);
+
 	{res_set, hosts_file=Option, Fname} ->
-	    handle_set_file(Option, Fname,
-			    res_hosts_file_tm, res_hosts_file_info,
-			    fun (Bin) ->
-				    case inet_parse:hosts(Fname,
-							  {chars,Bin}) of
-					{ok,Opts} ->
-					    [{load_hosts_file,Opts}];
-					_ -> error
-				    end
-			    end,
-			    From, State);
+	    handle_set_file(
+	      Option, Fname, res_hosts_file_tm, res_hosts_file_info,
+	      fun (Bin) ->
+		      case inet_parse:hosts(
+			     Fname, {chars,Bin}) of
+			  {ok,Opts} ->
+			      [{load_hosts_file,Opts}];
+			  _ -> error
+		      end
+	      end,
+	      From, State);
 	%%
 	{res_set, resolv_conf=Option, Fname} ->
-	    handle_set_file(Option, Fname,
-			    res_resolv_conf_tm, res_resolv_conf_info,
-			    fun (Bin) ->
-				    case inet_parse:resolv(Fname,
-							  {chars,Bin}) of
-					{ok,Opts} ->
-					    [del_ns,
-					     clear_search,
-					     clear_cache
-					     |[Opt ||
-						  {T,_}=Opt <- Opts,
-						  (T =:= nameserver orelse
-						   T =:= search)]];
-					_ -> error
-				    end
-			    end,
-			    From, State);
+	    handle_set_file(
+	      Option, Fname, res_resolv_conf_tm, res_resolv_conf_info,
+	      fun (Bin) ->
+		      case inet_parse:resolv(
+			     Fname, {chars,Bin}) of
+			  {ok,Opts} ->
+			      [del_ns,
+			       clear_search,
+			       clear_cache
+			       |[Opt ||
+				    {T,_}=Opt <- Opts,
+				    (T =:= nameserver orelse
+				     T =:= search)]];
+			  _ -> error
+		      end
+	      end,
+	      From, State);
 	%%
 	{res_set, Opt, Value} ->
 	    case res_optname(Opt) of
@@ -1156,6 +1173,12 @@ handle_set_file(Option, Fname, TagTm, TagInfo, ParseFun, From,
 	    ets:delete(Db, TagInfo),
 	    ets:delete(Db, TagTm),
 	    handle_set_file(ParseFun, <<>>, From, State);
+	true when ParseFun =:= undefined ->
+	    File = filename:flatten(Fname),
+	    ets:insert(Db, {res_optname(Option), File}),
+	    ets:insert(Db, {TagInfo, undefined}),
+	    ets:insert(Db, {TagTm, 0}),
+	    {reply,ok,State};
 	true ->
 	    File = filename:flatten(Fname),
 	    ets:insert(Db, {res_optname(Option), File}),
@@ -1178,7 +1201,8 @@ handle_set_file(Option, Fname, TagTm, TagInfo, ParseFun, From,
 
 handle_set_file(ParseFun, Bin, From, State) ->
     case ParseFun(Bin) of
-	error -> {reply,error,State};
+	error ->
+	    {reply,error,State};
 	Opts ->
 	    handle_rc_list(Opts, From, State)
     end.