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

Added support for the IP option MTU_DISCOVER.

OTP-14831

5 files changed, 266 insertions, 29 deletions

diff --git a/erts/emulator/nifs/common/socket_nif.c b/erts/emulator/nifs/common/socket_nif.c
index 6b9f27aa3f..65e530adee 100644
--- a/erts/emulator/nifs/common/socket_nif.c
+++ b/erts/emulator/nifs/common/socket_nif.c
@@ -365,6 +365,7 @@ typedef union {
 #define SOCKET_OPT_IP_ADD_MEMBERSHIP   1
 #define SOCKET_OPT_IP_DROP_MEMBERSHIP  5
 #define SOCKET_OPT_IP_MTU             11
+#define SOCKET_OPT_IP_MTU_DISCOVER    12
 #define SOCKET_OPT_IP_MULTICAST_IF    14
 #define SOCKET_OPT_IP_MULTICAST_LOOP  15
 #define SOCKET_OPT_IP_MULTICAST_TTL   16
@@ -866,6 +867,11 @@ ERL_NIF_TERM nsetopt_lvl_ip_update_membership(ErlNifEnv*        env,
                                               ERL_NIF_TERM      eVal,
                                               int               opt);
 #endif
+#if defined(IP_MTU_DISCOVER)
+static ERL_NIF_TERM nsetopt_lvl_ip_mtu_discover(ErlNifEnv*        env,
+                                                SocketDescriptor* descP,
+                                                ERL_NIF_TERM      eVal);
+#endif
 #if defined(IP_MULTICAST_IF)
 static ERL_NIF_TERM nsetopt_lvl_ip_multicast_if(ErlNifEnv*        env,
                                                 SocketDescriptor* descP,
@@ -1053,6 +1059,10 @@ static ERL_NIF_TERM ngetopt_lvl_ip(ErlNifEnv*        env,
 static ERL_NIF_TERM ngetopt_lvl_ip_mtu(ErlNifEnv*        env,
                                        SocketDescriptor* descP);
 #endif
+#if defined(IP_MTU_DISCOVER)
+static ERL_NIF_TERM ngetopt_lvl_ip_mtu_discover(ErlNifEnv*        env,
+                                                SocketDescriptor* descP);
+#endif
 #if defined(IP_MULTICAST_IF)
 static ERL_NIF_TERM ngetopt_lvl_ip_multicast_if(ErlNifEnv*        env,
                                                 SocketDescriptor* descP);
@@ -1282,9 +1292,22 @@ static void encode_address(ErlNifEnv*     env,
 static BOOLEAN_T decode_sock_linger(ErlNifEnv*     env,
                                     ERL_NIF_TERM   eVal,
                                     struct linger* valP);
+#if defined(IP_TOS)
 static BOOLEAN_T decode_ip_tos(ErlNifEnv*   env,
                                ERL_NIF_TERM eVal,
                                int*         val);
+#endif
+#if defined(IP_MTU_DISCOVER)
+static char* decode_ip_pmtudisc(ErlNifEnv*   env,
+                                ERL_NIF_TERM eVal,
+                                int*         val);
+#endif
+#if defined(IP_MTU_DISCOVER)
+static void encode_ip_pmtudisc(ErlNifEnv*    env,
+                               int           val,
+                               ERL_NIF_TERM* eVal);
+#endif
+
 /*
 static BOOLEAN_T decode_bool(ErlNifEnv*   env,
                              ERL_NIF_TERM eVal,
@@ -1416,6 +1439,8 @@ static const struct in6_addr in6addr_loopback =
 static char str_close[]        = "close";
 static char str_closed[]       = "closed";
 static char str_closing[]      = "closing";
+static char str_do[]           = "do";
+static char str_dont[]         = "dont";
 static char str_false[]        = "false";
 static char str_global_counters[] = "global_counters";
 static char str_in4_sockaddr[] = "in4_sockaddr";
@@ -1425,7 +1450,6 @@ static char str_interface[]    = "interface";
 // static char str_loopback[]     = "loopback";
 static char str_multiaddr[]    = "multiaddr";
 static char str_nif_abort[]    = "nif_abort";
-static char str_select[]       = "select";
 static char str_num_dlocal[]   = "num_domain_local";
 static char str_num_dinet[]    = "num_domain_inet";
 static char str_num_dinet6[]   = "num_domain_inet6";
@@ -1437,8 +1461,11 @@ static char str_num_sockets[]  = "num_sockets";
 static char str_num_tdgrams[]  = "num_type_dgram";
 static char str_num_tseqpkgs[] = "num_type_seqpacket";
 static char str_num_tstreams[] = "num_type_stream";
+static char str_probe[]        = "probe";
+static char str_select[]       = "select";
 static char str_timeout[]      = "timeout";
 static char str_true[]         = "true";
+static char str_want[]         = "want";
 
 static char str_lowdelay[]     = "lowdelay";
 static char str_throughput[]   = "throughput";
@@ -1498,6 +1525,8 @@ ERL_NIF_TERM esock_atom_einval;
 static ERL_NIF_TERM atom_close;
 static ERL_NIF_TERM atom_closed;
 static ERL_NIF_TERM atom_closing;
+static ERL_NIF_TERM atom_do;
+static ERL_NIF_TERM atom_dont;
 static ERL_NIF_TERM atom_false;
 static ERL_NIF_TERM atom_global_counters;
 static ERL_NIF_TERM atom_in4_sockaddr;
@@ -1517,9 +1546,11 @@ static ERL_NIF_TERM atom_num_sockets;
 static ERL_NIF_TERM atom_num_tdgrams;
 static ERL_NIF_TERM atom_num_tseqpkgs;
 static ERL_NIF_TERM atom_num_tstreams;
+static ERL_NIF_TERM atom_probe;
 static ERL_NIF_TERM atom_select;
 static ERL_NIF_TERM atom_timeout;
 static ERL_NIF_TERM atom_true;
+static ERL_NIF_TERM atom_want;
 
 static ERL_NIF_TERM atom_lowdelay;
 static ERL_NIF_TERM atom_throughput;
@@ -4008,6 +4039,12 @@ ERL_NIF_TERM nsetopt_lvl_ip(ErlNifEnv*        env,
         break;
 #endif
 
+#if defined(IP_MTU_DISCOVER)
+    case SOCKET_OPT_IP_MTU_DISCOVER:
+        result = nsetopt_lvl_ip_mtu_discover(env, descP, eVal);
+        break;
+#endif
+
 #if defined(IP_MULTICAST_IF)
     case SOCKET_OPT_IP_MULTICAST_IF:
         result = nsetopt_lvl_ip_multicast_if(env, descP, eVal);
@@ -4154,6 +4191,47 @@ ERL_NIF_TERM nsetopt_lvl_ip_update_membership(ErlNifEnv*        env,
 #endif
 
 
+/* nsetopt_lvl_ip_mtu_discover - Level IP MTU_DISCOVER option
+ *
+ * The value is an atom of the type ip_pmtudisc().
+ */
+#if defined(IP_MTU_DISCOVER)
+static
+ERL_NIF_TERM nsetopt_lvl_ip_mtu_discover(ErlNifEnv*        env,
+                                         SocketDescriptor* descP,
+                                         ERL_NIF_TERM      eVal)
+{
+    ERL_NIF_TERM   result;
+    int            val;
+    char*          xres;
+    int            res;
+#if defined(SOL_IP)
+    int            level = SOL_IP;
+#else
+    int            level = IPPROTO_IP;
+#endif
+
+    if ((xres = decode_ip_pmtudisc(env, eVal, &val)) != NULL) {
+
+        result = esock_make_error_str(env, xres);
+
+    } else {
+
+        res = socket_setopt(descP->sock, level, IP_MTU_DISCOVER,
+                            &val, sizeof(val));
+
+        if (res != 0)
+            result = esock_make_error_errno(env, sock_errno());
+        else
+            result = esock_atom_ok;
+
+    }
+
+    return result;
+}
+#endif
+
+
 /* nsetopt_lvl_ip_multicast_if - Level IP MULTICAST_IF option
  *
  * The value is either the atom 'any' or a 4-tuple.
@@ -5236,7 +5314,9 @@ ERL_NIF_TERM ngetopt_lvl_sock_domain(ErlNifEnv*        env,
 
         default:
             result = esock_make_error(env,
-                                      MKT2(env, esock_atom_unknown, MKI(env, val)));
+                                      MKT2(env,
+                                           esock_atom_unknown,
+                                           MKI(env, val)));
             break;
         }
     }
@@ -5464,6 +5544,12 @@ ERL_NIF_TERM ngetopt_lvl_ip(ErlNifEnv*        env,
         break;
 #endif
 
+#if defined(IP_MTU_DISCOVER)
+    case SOCKET_OPT_IP_MTU_DISCOVER:
+        result = ngetopt_lvl_ip_mtu_discover(env, descP);
+        break;
+#endif
+
 #if defined(IP_MULTICAST_IF)
     case SOCKET_OPT_IP_MULTICAST_IF:
         result = ngetopt_lvl_ip_multicast_if(env, descP);
@@ -5533,6 +5619,40 @@ ERL_NIF_TERM ngetopt_lvl_ip_mtu(ErlNifEnv*        env,
 #endif
 
 
+/* ngetopt_lvl_ip_mtu_discover - Level IP MTU_DISCOVER option
+ */
+#if defined(IP_MTU_DISCOVER)
+static
+ERL_NIF_TERM ngetopt_lvl_ip_mtu_discover(ErlNifEnv*        env,
+                                         SocketDescriptor* descP)
+{
+    ERL_NIF_TERM   result;
+    ERL_NIF_TERM   eMtuDisc;
+    int            mtuDisc;
+    SOCKOPTLEN_T   mtuDiscSz = sizeof(mtuDisc);
+    int            res;
+#if defined(SOL_IP)
+    int level = SOL_IP;
+#else
+    int level = IPPROTO_IP;
+#endif
+
+    res = sock_getopt(descP->sock, level, IP_MTU_DISCOVER,
+                      &mtuDisc, &mtuDiscSz);
+
+    if (res != 0) {
+        result = esock_make_error_errno(env, sock_errno());
+    } else {
+        encode_ip_pmtudisc(env, mtuDisc, &eMtuDisc);
+        result = esock_make_ok2(env, eMtuDisc);
+    }
+
+    return result;
+
+}
+#endif
+
+
 /* ngetopt_lvl_ip_multicast_if - Level IP MULTICAST_IF option
  */
 #if defined(IP_MULTICAST_IF)
@@ -6532,7 +6652,7 @@ BOOLEAN_T decode_sock_linger(ErlNifEnv* env, ERL_NIF_TERM eVal, struct linger* v
 
 
 
-/* +++ decode the ip socket option tos +++
+/* +++ decode the ip socket option TOS +++
  * The (ip) option can be provide in two ways:
  *
  *           atom() | integer()
@@ -6542,6 +6662,7 @@ BOOLEAN_T decode_sock_linger(ErlNifEnv* env, ERL_NIF_TERM eVal, struct linger* v
  *       lowdelay |  throughput | reliability | mincost
  *
  */
+#if defined(IP_TOS)
 static
 BOOLEAN_T decode_ip_tos(ErlNifEnv* env, ERL_NIF_TERM eVal, int* val)
 {
@@ -6596,6 +6717,100 @@ BOOLEAN_T decode_ip_tos(ErlNifEnv* env, ERL_NIF_TERM eVal, int* val)
 
     return result;
 }
+#endif
+
+
+
+/* +++ decode the ip socket option MTU_DISCOVER +++
+ * The (ip) option can be provide in two ways:
+ *
+ *           atom() | integer()
+ *
+ * When its an atom it can have the values:
+ *
+ *       want | dont | do | probe
+ *
+ */
+#if defined(IP_MTU_DISCOVER)
+static
+char* decode_ip_pmtudisc(ErlNifEnv* env, ERL_NIF_TERM eVal, int* val)
+{
+    char* res = NULL;
+
+    if (IS_ATOM(env, eVal)) {
+
+        if (COMPARE(eVal, atom_want) == 0) {
+            *val = IP_PMTUDISC_WANT;
+        } else if (COMPARE(eVal, atom_dont) == 0) {
+            *val = IP_PMTUDISC_DONT;
+        } else if (COMPARE(eVal, atom_do) == 0) {
+            *val = IP_PMTUDISC_DO;
+        } else if (COMPARE(eVal, atom_probe) == 0) {
+            *val = IP_PMTUDISC_PROBE;
+        } else {
+            *val = -1;
+            res  = ESOCK_STR_EINVAL;
+        }
+
+    } else if (IS_NUM(env, eVal)) {
+
+        if (!GET_INT(env, eVal, val)) {
+            *val = -1;
+            res  = ESOCK_STR_EINVAL;
+        }
+
+    } else {
+
+        *val   = -1;
+        res  = ESOCK_STR_EINVAL;
+
+    }
+
+    return res;
+}
+#endif
+
+
+
+/* +++ encode the ip socket option MTU_DISCOVER +++
+ * The (ip) option can be provide in two ways:
+ *
+ *           atom() | integer()
+ *
+ * If its one of the "known" values, it will be an atom:
+ *
+ *       want | dont | do | probe
+ *
+ */
+#if defined(IP_MTU_DISCOVER)
+static
+void encode_ip_pmtudisc(ErlNifEnv* env, int val, ERL_NIF_TERM* eVal)
+{
+    switch (val) {
+    case IP_PMTUDISC_WANT:
+        *eVal = atom_want;
+        break;
+
+    case IP_PMTUDISC_DONT:
+        *eVal = atom_dont;
+        break;
+
+    case IP_PMTUDISC_DO:
+        *eVal = atom_do;
+        break;
+
+    case IP_PMTUDISC_PROBE:
+        *eVal = atom_probe;
+        break;
+
+    default:
+        *eVal = MKI(env, val);
+        break;
+    }
+
+    return;
+}
+#endif
 
 
 
@@ -7664,6 +7879,8 @@ int on_load(ErlNifEnv* env, void** priv_data, ERL_NIF_TERM load_info)
     atom_close        = MKA(env, str_close);
     atom_closed       = MKA(env, str_closed);
     atom_closing      = MKA(env, str_closing);
+    atom_do           = MKA(env, str_do);
+    atom_dont         = MKA(env, str_dont);
     atom_false        = MKA(env, str_false);
     atom_global_counters = MKA(env, str_global_counters);
     atom_in4_sockaddr = MKA(env, str_in4_sockaddr);
@@ -7683,9 +7900,11 @@ int on_load(ErlNifEnv* env, void** priv_data, ERL_NIF_TERM load_info)
     atom_num_tdgrams  = MKA(env, str_num_tdgrams);
     atom_num_tseqpkgs = MKA(env, str_num_tseqpkgs);
     atom_num_tstreams = MKA(env, str_num_tstreams);
+    atom_probe        = MKA(env, str_probe);
     atom_select       = MKA(env, str_select);
     atom_timeout      = MKA(env, str_timeout);
     atom_true         = MKA(env, str_true);
+    atom_want         = MKA(env, str_want);
 
     /* Global atom(s) */
     esock_atom_addr      = MKA(env, "addr");
diff --git a/erts/preloaded/ebin/socket.beam b/erts/preloaded/ebin/socket.beam
index a172b48cdd..7ca451b6c5 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 d6b2289b69..5338f0d988 100644
--- a/erts/preloaded/src/socket.erl
+++ b/erts/preloaded/src/socket.erl
@@ -90,6 +90,7 @@
 
               ip_tos_flag/0,
               ip_mreq/0,
+              ip_pmtudisc/0,
 
 
               msg_hdr/0
@@ -149,6 +150,8 @@
 -type ip_mreq() :: #{multiaddr := ip4_address(),
                      interface := any | ip4_address()}.
 
+-type ip_pmtudisc() :: want | dont | do | probe.
+
 -type sockaddr_un()  :: #{family := local,
                           path   := binary() | string()}.
 -type sockaddr_in4() :: #{family := inet,
@@ -523,7 +526,7 @@
 %% -define(SOCKET_OPT_IP_MINTTL,                 9).
 %% -define(SOCKET_OPT_IP_MSFILTER,              10).
 -define(SOCKET_OPT_IP_MTU,                   11).
-%% -define(SOCKET_OPT_IP_MTU_DISCOVER,          12).
+-define(SOCKET_OPT_IP_MTU_DISCOVER,          12).
 %% -define(SOCKET_OPT_IP_MULTICAST_ALL,         13).
 -define(SOCKET_OPT_IP_MULTICAST_IF,          14).
 -define(SOCKET_OPT_IP_MULTICAST_LOOP,        15).
@@ -1982,6 +1985,13 @@ enc_setopt_value(ip, drop_membership, #{multiaddr := M,
   when (is_tuple(M) andalso (size(M) =:= 4)) andalso 
        ((IF =:= any) orelse (is_tuple(IF) andalso (size(IF) =:= 4))) ->
     V;
+enc_setopt_value(ip, mtu_discover, V, _D, _T, _P)
+  when (V =:= want)  orelse
+       (V =:= dont)  orelse
+       (V =:= do)    orelse
+       (V =:= probe) orelse
+       is_integer(V) ->
+    V;
 enc_setopt_value(ip, multicast_if, V, _D, _T, _P)
   when (V =:= any) orelse (is_tuple(V) andalso (size(V) =:= 4)) ->
     V;
@@ -2277,8 +2287,8 @@ enc_sockopt_key(ip = L, msfilter = Opt, _Dir, _D, _T, _P) ->
     not_supported({L, Opt});
 enc_sockopt_key(ip = _L, mtu = _Opt, get = _Dir, _D, _T, _P) ->
     ?SOCKET_OPT_IP_MTU;
-enc_sockopt_key(ip = L, mtu_discover = Opt, _Dir, _D, _T, _P) ->
-    not_supported({L, Opt});
+enc_sockopt_key(ip = _L, mtu_discover = _Opt, _Dir, _D, _T, _P) ->
+    ?SOCKET_OPT_IP_MTU_DISCOVER;
 enc_sockopt_key(ip = L, multicast_all = Opt, _Dir, _D, _T, _P) ->
     not_supported({L, Opt});
 enc_sockopt_key(ip = _L, multicast_if = _Opt, _Dir, _D, _T, _P) ->
diff --git a/lib/kernel/test/socket_client.erl b/lib/kernel/test/socket_client.erl
index dce50682ab..6c6dc0444c 100644
--- a/lib/kernel/test/socket_client.erl
+++ b/lib/kernel/test/socket_client.erl
@@ -71,19 +71,20 @@ do_start(Domain, stream = Type, Proto, SA) ->
     try do_init(Domain, Type, Proto) of
         Sock ->
             connect(Sock, SA),
-            {ok, Name} = socket:sockname(Sock), 
-            {ok, Peer} = socket:peername(Sock),
-            {ok, Domain} = socket:getopt(Sock, socket, domain),
-            {ok, Type}   = socket:getopt(Sock, socket, type),
-            {ok, Proto}  = socket:getopt(Sock, socket, protocol),
-            {ok, OOBI}   = socket:getopt(Sock, socket, oobinline),
-            {ok, SndBuf} = socket:getopt(Sock, socket, sndbuf),
-            {ok, RcvBuf} = socket:getopt(Sock, socket, rcvbuf),
-            {ok, Linger} = socket:getopt(Sock, socket, linger),
-            {ok, MTU}    = socket:getopt(Sock, ip,     mtu),
-            {ok, MIF}    = socket:getopt(Sock, ip,     multicast_if),
-            {ok, MLoop}  = socket:getopt(Sock, ip,     multicast_loop),
-            {ok, MTTL}   = socket:getopt(Sock, ip,     multicast_ttl),
+            {ok, Name}    = socket:sockname(Sock),
+            {ok, Peer}    = socket:peername(Sock),
+            {ok, Domain}  = socket:getopt(Sock, socket, domain),
+            {ok, Type}    = socket:getopt(Sock, socket, type),
+            {ok, Proto}   = socket:getopt(Sock, socket, protocol),
+            {ok, OOBI}    = socket:getopt(Sock, socket, oobinline),
+            {ok, SndBuf}  = socket:getopt(Sock, socket, sndbuf),
+            {ok, RcvBuf}  = socket:getopt(Sock, socket, rcvbuf),
+            {ok, Linger}  = socket:getopt(Sock, socket, linger),
+            {ok, MTU}     = socket:getopt(Sock, ip,     mtu),
+            {ok, MTUDisc} = socket:getopt(Sock, ip,     mtu_discover),
+            {ok, MIF}     = socket:getopt(Sock, ip,     multicast_if),
+            {ok, MLoop}   = socket:getopt(Sock, ip,     multicast_loop),
+            {ok, MTTL}    = socket:getopt(Sock, ip,     multicast_ttl),
             i("connected: "
               "~n   From: ~p"
               "~n   To:   ~p"
@@ -96,13 +97,15 @@ do_start(Domain, stream = Type, Proto, SA) ->
               "~n   (socket) RcvBuf:         ~p"
               "~n   (socket) Linger:         ~p"
               "~n   (ip)     MTU:            ~p"
+              "~n   (ip)     MTU Discovery:  ~p"
               "~n   (ip)     Multicast IF:   ~p"
               "~n   (ip)     Multicast Loop: ~p"
               "~n   (ip)     Multicast TTL:  ~p"
               "~n   => wait some", 
               [Name, Peer,
-               Domain, Type, Proto, 
-               OOBI, SndBuf, RcvBuf, Linger, MTU, MIF, MLoop, MTTL]),
+               Domain, Type, Proto,
+               OOBI, SndBuf, RcvBuf, Linger,
+               MTU, MTUDisc, MIF, MLoop, MTTL]),
             %% Give the server some time...
             ?LIB:sleep(5000),
             %% ok = socket:close(Sock),
diff --git a/lib/kernel/test/socket_server.erl b/lib/kernel/test/socket_server.erl
index f77c91996f..68a6aebc50 100644
--- a/lib/kernel/test/socket_server.erl
+++ b/lib/kernel/test/socket_server.erl
@@ -435,6 +435,13 @@ handler_init(Manager, ID, Peek, Sock) ->
         {handler, Pid, Ref, continue} ->
             i("got continue"),
             handler_reply(Pid, Ref, ok),
+            G = fun(K) -> case socket:getopt(Sock, ip, K) of
+                      {ok, Val} ->
+                          f("~w", [Val]);
+                      {error, _} ->
+                          "-"
+                          end
+                end,
             {ok, Domain} = socket:getopt(Sock, socket, domain),
             {ok, Type}   = socket:getopt(Sock, socket, type),
             {ok, Proto}  = socket:getopt(Sock, socket, protocol),
@@ -442,12 +449,8 @@ handler_init(Manager, ID, Peek, Sock) ->
             {ok, SndBuf} = socket:getopt(Sock, socket, sndbuf),
             {ok, RcvBuf} = socket:getopt(Sock, socket, rcvbuf),
             {ok, Linger} = socket:getopt(Sock, socket, linger),
-            MTU = case socket:getopt(Sock, ip, mtu) of
-                      {ok, Val} ->
-                          f("~w", [Val]);
-                      {error, _} ->
-                          "-" % We don't connect UDP (it can be done but we don't)
-                  end,
+            MTU     = G(mtu),
+            MTUDisc = G(mtu_discover),
             {ok, MIF}    = socket:getopt(Sock, ip,     multicast_if),
             {ok, MLoop}  = socket:getopt(Sock, ip,     multicast_loop),
             {ok, MTTL}   = socket:getopt(Sock, ip,     multicast_ttl),
@@ -460,11 +463,13 @@ handler_init(Manager, ID, Peek, Sock) ->
               "~n   (socket) RcvBuf:         ~p"
               "~n   (socket) Linger:         ~p"
               "~n   (ip)     MTU:            ~s"
+              "~n   (ip)     MTU Discovery:  ~s"
               "~n   (ip)     Multicast IF:   ~p"
               "~n   (ip)     Multicast Loop: ~p"
               "~n   (ip)     Multicast TTL:  ~p", 
-              [Domain, Type, Proto, 
-               OOBI, SndBuf, RcvBuf, Linger, MTU, MIF, MLoop, MTTL]),
+              [Domain, Type, Proto,
+               OOBI, SndBuf, RcvBuf, Linger,
+               MTU, MTUDisc, MIF, MLoop, MTTL]),
             %% socket:setopt(Sock, otp, debug, true),
             handler_loop(#handler{peek    = Peek,
                                   manager = Manager,