1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
|
%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 1996-2013. 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(net_adm).
-export([host_file/0,
localhost/0,
names/0, names/1,
ping_list/1,
world/0,world/1,
world_list/1, world_list/2,
dns_hostname/1,
ping/1]).
%%------------------------------------------------------------------------
-type verbosity() :: 'silent' | 'verbose'.
%%------------------------------------------------------------------------
%% Try to read .hosts.erlang file in
%% 1. cwd , 2. $HOME 3. init:root_dir()
-spec host_file() -> Hosts | {error, Reason} when
Hosts :: [Host :: atom()],
%% Copied from file:path_consult/2:
Reason :: file:posix() | badarg | terminated | system_limit
| {Line :: integer(), Mod :: module(), Term :: term()}.
host_file() ->
Home = case init:get_argument(home) of
{ok, [[H]]} -> [H];
_ -> []
end,
case file:path_consult(["."] ++ Home ++ [code:root_dir()], ".hosts.erlang") of
{ok, Hosts, _} -> Hosts;
Error -> Error
end.
%% Check whether a node is up or down
%% side effect: set up a connection to Node if there not yet is one.
-spec ping(Node) -> pong | pang when
Node :: atom().
ping(Node) when is_atom(Node) ->
case catch gen:call({net_kernel, Node},
'$gen_call',
{is_auth, node()},
infinity) of
{ok, yes} -> pong;
_ ->
erlang:disconnect_node(Node),
pang
end.
-spec localhost() -> Name when
Name :: string().
localhost() ->
{ok, Host} = inet:gethostname(),
case inet_db:res_option(domain) of
"" -> Host;
Domain -> Host ++ "." ++ Domain
end.
-spec names() -> {ok, [{Name, Port}]} | {error, Reason} when
Name :: string(),
Port :: non_neg_integer(),
Reason :: address | file:posix().
names() ->
names(localhost()).
-spec names(Host) -> {ok, [{Name, Port}]} | {error, Reason} when
Host :: atom() | string(),
Name :: string(),
Port :: non_neg_integer(),
Reason :: address | file:posix().
names(Hostname) ->
case inet:gethostbyname(Hostname) of
{ok, {hostent, _Name, _ , _Af, _Size, [Addr | _]}} ->
erl_epmd:names(Addr);
Else ->
Else
end.
-spec dns_hostname(Host) -> {ok, Name} | {error, Host} when
Host :: atom() | string(),
Name :: string().
dns_hostname(Hostname) ->
case inet:gethostbyname(Hostname) of
{ok,{hostent, Name, _ , _Af, _Size, _Addr}} ->
{ok, Name};
_ ->
{error, Hostname}
end.
%% A common situation in "life" is to have a configuration file with a list
%% of nodes, and then at startup, all nodes in the list are ping'ed
%% this can lead to no end of troubles if two disconnected nodes
%% simultaneously ping each other.
%% Use this function in order to do it safely.
%% It assumes a working global.erl which ensures a fully
%% connected network.
%% Had the erlang runtime system been able to fully cope with
%% the possibility of two simultaneous (unix) connects, this function would
%% merley be lists:map({net_adm, ping}, [], Nodelist).
%% It is also assumed, that the same (identical) Nodelist is given to all
%% nodes which are to perform this call (possibly simultaneously).
%% Even this code has a flaw, and that is the case where two
%% nodes simultaneously and without *any* other already
%% running nodes execute this code. :-(
-spec ping_list([atom()]) -> [atom()].
ping_list(Nodelist) ->
ok = net_kernel:monitor_nodes(true),
Sofar = ping_first(Nodelist, nodes()),
collect_new(Sofar, Nodelist).
ping_first([], _S) ->
[];
ping_first([Node|Nodes], S) ->
case lists:member(Node, S) of
true -> [Node | ping_first(Nodes, S)];
false ->
case ping(Node) of
pong -> [Node];
pang -> ping_first(Nodes, S)
end
end.
collect_new(Sofar, Nodelist) ->
receive
{nodeup, Node} ->
case lists:member(Node, Nodelist) of
true ->
collect_new(Sofar, Nodelist);
false ->
collect_new([Node | Sofar], Nodelist)
end
after 3000 ->
ok = net_kernel:monitor_nodes(false),
Sofar
end.
%% This function polls a set of hosts according to a file called
%% .hosts.erlang that need to reside either in the current directory
%% or in your home directory. (The current directory is tried first.)
%% world() returns a list of all nodes on the network that can be
%% found (including ourselves). Note: the $HOME variable is inspected.
%%
%% Added possibility to supply a list of hosts instead of reading
%% the .hosts.erlang file. 971016 patrik@erix.ericsson.se
%% e.g.
%% net_adm:world_list(['elrond.du.etx.ericsson.se', 'thorin.du.etx.ericsson.se']).
-spec world() -> [node()].
world() ->
world(silent).
-spec world(Arg) -> [node()] when
Arg :: verbosity().
world(Verbose) ->
case net_adm:host_file() of
{error,R} -> exit({error, R});
Hosts -> expand_hosts(Hosts, Verbose)
end.
-spec world_list(Hosts) -> [node()] when
Hosts :: [atom()].
world_list(Hosts) when is_list(Hosts) ->
expand_hosts(Hosts, silent).
-spec world_list(Hosts, Arg) -> [node()] when
Hosts :: [atom()],
Arg :: verbosity().
world_list(Hosts, Verbose) when is_list(Hosts) ->
expand_hosts(Hosts, Verbose).
expand_hosts(Hosts, Verbose) ->
lists:flatten(collect_nodes(Hosts, Verbose)).
collect_nodes([], _) -> [];
collect_nodes([Host|Tail], Verbose) ->
case collect_host_nodes(Host, Verbose) of
nil ->
collect_nodes(Tail, Verbose);
L ->
[L|collect_nodes(Tail, Verbose)]
end.
collect_host_nodes(Host, Verbose) ->
case names(Host) of
{ok, Namelist} ->
do_ping(Namelist, atom_to_list(Host), Verbose);
_ ->
nil
end.
do_ping(Names, Host0, Verbose) ->
case longshort(Host0) of
ignored -> [];
Host -> do_ping_1(Names, Host, Verbose)
end.
do_ping_1([], _Host, _Verbose) ->
[];
do_ping_1([{Name, _} | Rest], Host, Verbose) ->
Node = list_to_atom(Name ++ "@" ++ longshort(Host)),
verbose(Verbose, "Pinging ~w -> ", [Node]),
Result = ping(Node),
verbose(Verbose, "~p\n", [Result]),
case Result of
pong ->
[Node | do_ping_1(Rest, Host, Verbose)];
pang ->
do_ping_1(Rest, Host, Verbose)
end.
verbose(verbose, Format, Args) ->
io:format(Format, Args);
verbose(_, _, _) ->
ok.
longshort(Host) ->
case net_kernel:longnames() of
false -> uptodot(Host);
true -> Host;
ignored -> ignored
end.
uptodot([$.|_]) -> [];
uptodot([])-> [];
uptodot([H|T]) -> [H|uptodot(T)].
|
