[enet] Add first version of filter arg to getifaddrs

Added the function getifaddrs/1,2 that takes a filter
argument, which makes it possible to filter out only
those interfaces that "belong" to that specific
(socket) address family.

OTP-16212

1 files changed, 59 insertions, 3 deletions

diff --git a/lib/kernel/src/net.erl b/lib/kernel/src/net.erl
index e2ccbdc9c5..331582c47a 100644
--- a/lib/kernel/src/net.erl
+++ b/lib/kernel/src/net.erl
@@ -37,7 +37,7 @@
          gethostname/0,
          getnameinfo/1, getnameinfo/2,
          getaddrinfo/1, getaddrinfo/2,
-         getifaddrs/0,  getifaddrs/1,
+         getifaddrs/0,  getifaddrs/1, getifaddrs/2,
 
          if_name2index/1,
          if_index2name/1,
@@ -94,6 +94,9 @@
                      broadaddr := socket:sockaddr(),
                      dstaddr   := socket:sockaddr()}.
 
+-type ifaddrs_filter_map() :: #{family := default | inet | inet6 | all,
+                                flags  := any | ifaddrs_flags()}.
+
 -type name_info_flags()         :: [name_info_flag()|name_info_flag_ext()].
 -type name_info_flag()          :: namereqd |
                                    dgram |
@@ -287,7 +290,7 @@ getaddrinfo(Host, Service)
 
 -ifdef(USE_ESOCK).
 getifaddrs() ->
-    prim_net:getifaddrs(#{}).
+    getifaddrs(getifaddrs_filter_map_default()).
 -else.
 getifaddrs() ->
     erlang:error(notsup).
@@ -297,18 +300,71 @@ getifaddrs() ->
 -spec getifaddrs(Namespace) -> {ok, IfAddrs} | {error, Reason} when
       Namespace :: file:filename_all(),
       IfAddrs   :: [ifaddrs()],
+      Reason    :: term();
+                (FilterMap) -> {ok, IfAddrs} | {error, Reason} when
+      FilterMap :: ifaddrs_filter_map(),
+      IfAddrs   :: [ifaddrs()],
       Reason    :: term().
 
 -ifdef(USE_ESOCK).
 getifaddrs(Namespace) when is_list(Namespace) ->
-    prim_net:getifaddrs(#{netns => Namespace}).
+    prim_net:getifaddrs(#{netns => Namespace});
+getifaddrs(FilterMap) when is_map(FilterMap) ->
+    do_getifaddrs(getifaddrs_filter_map(FilterMap),
+                  fun() -> prim_net:getifaddrs(#{}) end).
 -else.
 -dialyzer({nowarn_function, getifaddrs/1}).
 getifaddrs(Namespace) when is_list(Namespace) ->
+    erlang:error(notsup);
+getifaddrs(FilterMap) when is_map(FilterMap) ->
     erlang:error(notsup).
 -endif.
 
 
+-spec getifaddrs(FilterMap, Namespace) -> {ok, IfAddrs} | {error, Reason} when
+      FilterMap :: ifaddrs_filter_map(),
+      Namespace :: file:filename_all(),
+      IfAddrs   :: [ifaddrs()],
+      Reason    :: term().
+
+getifaddrs(FilterMap, Namespace)
+  when is_map(FilterMap) andalso is_list(Namespace) ->
+    do_getifaddrs(getifaddrs_filter_map(FilterMap),
+                  fun() -> getifaddrs(Namespace) end).
+
+do_getifaddrs(FilterMap, GetIfAddrs) ->
+    case GetIfAddrs() of
+        {ok, IfAddrs0} ->
+            Filter = fun(Elem) -> getifaddrs_filter(FilterMap, Elem) end,
+            {ok, lists:filtermap(Filter, IfAddrs0)};
+        {error, _} = ERROR ->
+            ERROR
+    end.
+
+getifaddrs_filter_map(FilterMap) ->
+    maps:merge(getifaddrs_filter_map_default(), FilterMap).
+
+getifaddrs_filter_map_default() ->
+    #{family => default, flags => any}.
+
+getifaddrs_filter(#{family := FFamily},
+                  #{addr := #{family := Family}} = _Entry)
+  when (FFamily =:= default) andalso
+       ((Family =:= inet) orelse (Family =:= inet6)) ->
+    true;
+getifaddrs_filter(#{family := FFamily},
+                  #{addr := #{family := Family}} = _Entry)
+  when (FFamily =:= inet) andalso (Family =:= inet) ->
+    true;
+getifaddrs_filter(#{family := FFamily},
+                  #{addr := #{family := Family}} = _Entry)
+  when (FFamily =:= inet6) andalso (Family =:= inet6) ->
+    true;
+getifaddrs_filter(#{family := FFamily}, _Entry)
+  when (FFamily =:= all) ->
+    true;
+getifaddrs_filter(_Filter, _Entry) ->
+    false.
 
 
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