[socket-nif] Add support for socket (level ip) option freebind

Added support for ip level socket option FREEBIND.

Note that there is an option available on FreeBSD called
IP_BINDANY, which seems to have similar properties (FREEBIND
is *not* available on FreeBSD). There are some restrictions
for this option though (which is not mentioned in the Linux
man page).

OTP-14831

5 files changed, 83 insertions, 5 deletions

diff --git a/erts/doc/src/socket_usage.xml b/erts/doc/src/socket_usage.xml
index c875ecd6f0..a286171a1b 100644
--- a/erts/doc/src/socket_usage.xml
+++ b/erts/doc/src/socket_usage.xml
@@ -289,6 +289,13 @@
 	<cell>none</cell>
       </row>
       <row>
+	<cell>freebind</cell>
+	<cell>boolean()</cell>
+	<cell>yes</cell>
+	<cell>yes</cell>
+	<cell>none</cell>
+      </row>
+      <row>
 	<cell>minttl</cell>
 	<cell>integer()</cell>
 	<cell>yes</cell>
diff --git a/erts/emulator/nifs/common/socket_nif.c b/erts/emulator/nifs/common/socket_nif.c
index 6df2020e5e..f319f171ad 100644
--- a/erts/emulator/nifs/common/socket_nif.c
+++ b/erts/emulator/nifs/common/socket_nif.c
@@ -517,6 +517,7 @@ typedef union {
 #define SOCKET_OPT_IP_BLOCK_SOURCE            3
 #define SOCKET_OPT_IP_DROP_MEMBERSHIP         5
 #define SOCKET_OPT_IP_DROP_SOURCE_MEMBERSHIP  6
+#define SOCKET_OPT_IP_FREEBIND                7
 #define SOCKET_OPT_IP_MINTTL                  9
 #define SOCKET_OPT_IP_MTU                    11
 #define SOCKET_OPT_IP_MTU_DISCOVER           12
@@ -1086,6 +1087,11 @@ static ERL_NIF_TERM nsetopt_lvl_ip_drop_source_membership(ErlNifEnv*        env,
                                                           SocketDescriptor* descP,
                                                           ERL_NIF_TERM      eVal);
 #endif
+#if defined(IP_FREEBIND)
+static ERL_NIF_TERM nsetopt_lvl_ip_freebind(ErlNifEnv*        env,
+                                            SocketDescriptor* descP,
+                                            ERL_NIF_TERM      eVal);
+#endif
 #if defined(IP_MINTTL)
 static ERL_NIF_TERM nsetopt_lvl_ip_minttl(ErlNifEnv*        env,
                                           SocketDescriptor* descP,
@@ -1408,6 +1414,10 @@ static ERL_NIF_TERM ngetopt_lvl_sock_type(ErlNifEnv*        env,
 static ERL_NIF_TERM ngetopt_lvl_ip(ErlNifEnv*        env,
                                    SocketDescriptor* descP,
                                    int               eOpt);
+#if defined(IP_FREEBIND)
+static ERL_NIF_TERM ngetopt_lvl_ip_freebind(ErlNifEnv*        env,
+                                            SocketDescriptor* descP);
+#endif
 #if defined(IP_MINTTL)
 static ERL_NIF_TERM ngetopt_lvl_ip_minttl(ErlNifEnv*        env,
                                           SocketDescriptor* descP);
@@ -4738,6 +4748,12 @@ ERL_NIF_TERM nsetopt_lvl_ip(ErlNifEnv*        env,
         break;
 #endif
 
+#if defined(IP_FREEBIND)
+    case SOCKET_OPT_IP_FREEBIND:
+        result = nsetopt_lvl_ip_freebind(env, descP, eVal);
+        break;
+#endif
+
 #if defined(IP_MINTTL)
     case SOCKET_OPT_IP_MINTTL:
         result = nsetopt_lvl_ip_minttl(env, descP, eVal);
@@ -4936,6 +4952,26 @@ ERL_NIF_TERM nsetopt_lvl_ip_drop_source_membership(ErlNifEnv*        env,
 
 
 
+/* nsetopt_lvl_ip_freebind - Level IP FREEBIND option
+ */
+#if defined(IP_FREEBIND)
+static
+ERL_NIF_TERM nsetopt_lvl_ip_freebind(ErlNifEnv*        env,
+                                     SocketDescriptor* descP,
+                                     ERL_NIF_TERM      eVal)
+{
+#if defined(SOL_IP)
+    int level = SOL_IP;
+#else
+    int level = IPPROTO_IP;
+#endif
+
+    return nsetopt_bool_opt(env, descP, level, IP_FREEBIND, eVal);
+}
+#endif
+
+
+
 /* nsetopt_lvl_ip_minttl - Level IP MINTTL option
  */
 #if defined(IP_MINTTL)
@@ -7374,6 +7410,12 @@ ERL_NIF_TERM ngetopt_lvl_ip(ErlNifEnv*        env,
     ERL_NIF_TERM result;
 
     switch (eOpt) {
+#if defined(IP_FREEBIND)
+    case SOCKET_OPT_IP_FREEBIND:
+        result = ngetopt_lvl_ip_freebind(env, descP);
+        break;
+#endif
+
 #if defined(IP_MINTTL)
     case SOCKET_OPT_IP_MINTTL:
         result = ngetopt_lvl_ip_minttl(env, descP);
@@ -7485,6 +7527,24 @@ ERL_NIF_TERM ngetopt_lvl_ip_minttl(ErlNifEnv*        env,
 #endif
 
 
+/* ngetopt_lvl_ip_freebind - Level IP FREEBIND option
+ */
+#if defined(IP_FREEBIND)
+static
+ERL_NIF_TERM ngetopt_lvl_ip_freebind(ErlNifEnv*        env,
+                                     SocketDescriptor* descP)
+{
+#if defined(SOL_IP)
+    int level = SOL_IP;
+#else
+    int level = IPPROTO_IP;
+#endif
+
+    return ngetopt_bool_opt(env, descP, level, IP_FREEBIND);
+}
+#endif
+
+
 /* ngetopt_lvl_ip_mtu - Level IP MTU option
  */
 #if defined(IP_MTU)
diff --git a/erts/preloaded/ebin/socket.beam b/erts/preloaded/ebin/socket.beam
index 8799f07bc0..3657212f81 100644
--- a/erts/preloaded/ebin/socket.beam
+++ b/erts/preloaded/ebin/socket.beam
diff --git a/erts/preloaded/src/socket.erl b/erts/preloaded/src/socket.erl
index c231647f8c..329223c443 100644
--- a/erts/preloaded/src/socket.erl
+++ b/erts/preloaded/src/socket.erl
@@ -87,6 +87,7 @@
               tcp_socket_option/0,
               udp_socket_option/0,
               sctp_socket_option/0,
+              raw_socket_option/0,
 
               timeval/0,
               ip_tos_flag/0,
@@ -258,7 +259,7 @@
 %% Int    - Raw level, sent down and used "as is".
 -type sockopt_level() :: otp |
                          socket |
-                         ip | ipv6 | tcp | udp | sctp |
+                         ip | ipv6 | tcp | udp | sctp | raw |
                          non_neg_integer().
 
 %% There are some options that are 'read-only'.
@@ -434,6 +435,8 @@
         status |
         use_ext_recvinfo.
 
+-type raw_socket_option() :: filter.
+
 %% -type plain_socket_option()  :: integer().
 %% -type sockopt() :: otp_socket_option() |
 %%                    socket_option() |
@@ -442,6 +445,7 @@
 %%                    tcp_socket_option() |
 %%                    udp_socket_option() |
 %%                    sctp_socket_option() |
+%%                    raw_socket_option() |
 %%                    plain_socket_option().
 
 -type socket_info() :: #{domain   => domain(),
@@ -594,7 +598,7 @@
 %% -define(SOCKET_OPT_IP_DONTFRAG,               4).
 -define(SOCKET_OPT_IP_DROP_MEMBERSHIP,        5).
 -define(SOCKET_OPT_IP_DROP_SOURCE_MEMBERSHIP, 6).
-%% -define(SOCKET_OPT_IP_FREEBIND,               7).
+-define(SOCKET_OPT_IP_FREEBIND,               7).
 %% -define(SOCKET_OPT_IP_HDRINCL,                8).
 -define(SOCKET_OPT_IP_MINTTL,                 9).
 %% -define(SOCKET_OPT_IP_MSFILTER,              10).
@@ -2177,6 +2181,8 @@ enc_setopt_value(ip, drop_source_membership, #{multiaddr  := MA,
        (is_tuple(IF) andalso (size(IF) =:= 4)) andalso
        (is_tuple(SA) andalso (size(SA) =:= 4)) ->
     V;
+enc_setopt_value(ip, freebind, V, _D, _T, _P) when is_boolean(V) ->
+    V;
 enc_setopt_value(ip, minttl, V, _D, _T, _P) when is_integer(V) ->
     V;
 enc_setopt_value(ip, mtu_discover, V, _D, _T, _P)
@@ -2358,6 +2364,9 @@ enc_setopt_value(sctp, rtoinfo, #{assoc_id := AssocId,
 enc_setopt_value(sctp = L, Opt, V, _D, _T, _P) ->
     not_supported({L, Opt, V});
 
+enc_setopt_value(raw = L, Opt, _V, _D, _T, _P) ->
+    not_supported({L, Opt});
+
 %% Is this correct? What about getopt?
 enc_setopt_value(L, Opt, V, _, _, _)
   when is_integer(L) andalso is_integer(Opt) andalso is_binary(V) ->
@@ -2574,8 +2583,8 @@ enc_sockopt_key(ip = _L, drop_membership = _Opt, set = _Dir, _D, _T, _P) ->
 enc_sockopt_key(ip = _L, drop_source_membership = _Opt, set = _Dir, _D, _T, _P) ->
     ?SOCKET_OPT_IP_DROP_SOURCE_MEMBERSHIP;
 %% Linux only?
-enc_sockopt_key(ip = L, free_bind = Opt, _Dir, _D, _T, _P) ->
-    not_supported({L, Opt});
+enc_sockopt_key(ip = _L, freebind = _Opt, _Dir, _D, _T, _P) ->
+    ?SOCKET_OPT_IP_FREEBIND;
 enc_sockopt_key(ip = L, hdrincl = Opt, _Dir, _D, raw = _T, _P) ->
     not_supported({L, Opt});
 %% FreeBSD only?
diff --git a/lib/kernel/test/socket_server.erl b/lib/kernel/test/socket_server.erl
index 6aa26494f7..971ceb2093 100644
--- a/lib/kernel/test/socket_server.erl
+++ b/lib/kernel/test/socket_server.erl
@@ -604,6 +604,7 @@ handler_init(Manager, ID, Peek, Sock) ->
             SndTO        = GSO(sndtimeo),
             Linger       = GSO(linger),
             Timestamp    = GSO(timestamp),
+            FreeBind     = GIP(freebind),
             MTU          = GIP(mtu),
             MTUDisc      = GIP(mtu_discover),
             MALL         = GIP(multicast_all),
@@ -629,6 +630,7 @@ handler_init(Manager, ID, Peek, Sock) ->
               "~n   (socket) SndTO:          ~s"
               "~n   (socket) Linger:         ~s"
               "~n   (socket) Timestamp:      ~s"
+              "~n   (ip)     FreeBind:       ~s"
               "~n   (ip)     MTU:            ~s"
               "~n   (ip)     MTU Discovery:  ~s"
               "~n   (ip)     Multicast ALL:  ~s"
@@ -642,7 +644,7 @@ handler_init(Manager, ID, Peek, Sock) ->
                RA, RP, B2D, OOBI,
                RcvBuf, RcvLW, RcvTO, SndBuf, SndLW, SndTO,
                Linger, Timestamp,
-               MTU, MTUDisc, MALL, MIF, MLoop, MTTL,
+               FreeBind, MTU, MTUDisc, MALL, MIF, MLoop, MTTL,
                NF, RecvTOS, RecvTTL]),
             
             handler_loop(#handler{peek    = Peek,