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

Added support for ip level socket option SENDSRCADDR.
This option requires sendmsg to actually use, so we
cannot test this fully at the moment.

OTP-14831

4 files changed, 77 insertions, 2 deletions

diff --git a/erts/doc/src/socket_usage.xml b/erts/doc/src/socket_usage.xml
index f69aa75820..933341bd35 100644
--- a/erts/doc/src/socket_usage.xml
+++ b/erts/doc/src/socket_usage.xml
@@ -35,6 +35,10 @@
     <p>The socket interface (module) is basically an "thin" layer on top of
     the OS socket interface. It is assumed that, unless you have special needs,
     gen_[tcp|udp|sctp] should be sufficent. </p>
+    <p>Note that just because we have a documented and described option,
+    it does <em>not</em> mean that the OS supports it. So its recommended
+    that the user reads the platform specific documentation for the
+    option used. </p>
   </section>
 
   <section>
@@ -429,6 +433,13 @@
 	<cell>type = raw</cell>
       </row>
       <row>
+	<cell>sendsrcaddr</cell>
+	<cell>boolean()</cell>
+	<cell>yes</cell>
+	<cell>yes</cell>
+	<cell>none</cell>
+      </row>
+      <row>
 	<cell>tos</cell>
 	<cell>ip_tos()</cell>
 	<cell>yes</cell>
diff --git a/erts/emulator/nifs/common/socket_nif.c b/erts/emulator/nifs/common/socket_nif.c
index 4ba94f4f60..13250349db 100644
--- a/erts/emulator/nifs/common/socket_nif.c
+++ b/erts/emulator/nifs/common/socket_nif.c
@@ -540,6 +540,7 @@ typedef union {
 #define SOCKET_OPT_IP_RECVTTL                26
 #define SOCKET_OPT_IP_RETOPTS                27
 #define SOCKET_OPT_IP_ROUTER_ALERT           28
+#define SOCKET_OPT_IP_SENDSRCADDR            29 // Same as IP_RECVDSTADDR?
 #define SOCKET_OPT_IP_TOS                    30
 #define SOCKET_OPT_IP_TRANSPARENT            31
 #define SOCKET_OPT_IP_TTL                    32
@@ -1218,6 +1219,11 @@ static ERL_NIF_TERM nsetopt_lvl_ip_router_alert(ErlNifEnv*        env,
                                                 SocketDescriptor* descP,
                                                 ERL_NIF_TERM      eVal);
 #endif
+#if defined(IP_SENDSRCADDR)
+static ERL_NIF_TERM nsetopt_lvl_ip_sendsrcaddr(ErlNifEnv*        env,
+                                               SocketDescriptor* descP,
+                                               ERL_NIF_TERM      eVal);
+#endif
 #if defined(IP_TOS)
 static ERL_NIF_TERM nsetopt_lvl_ip_tos(ErlNifEnv*        env,
                                        SocketDescriptor* descP,
@@ -1640,6 +1646,10 @@ static ERL_NIF_TERM ngetopt_lvl_ip_retopts(ErlNifEnv*        env,
 static ERL_NIF_TERM ngetopt_lvl_ip_router_alert(ErlNifEnv*        env,
                                                 SocketDescriptor* descP);
 #endif
+#if defined(IP_SENDSRCADDR)
+static ERL_NIF_TERM ngetopt_lvl_ip_sendsrcaddr(ErlNifEnv*        env,
+                                               SocketDescriptor* descP);
+#endif
 #if defined(IP_TOS)
 static ERL_NIF_TERM ngetopt_lvl_ip_tos(ErlNifEnv*        env,
                                        SocketDescriptor* descP);
@@ -5125,6 +5135,12 @@ ERL_NIF_TERM nsetopt_lvl_ip(ErlNifEnv*        env,
         break;
 #endif
 
+#if defined(IP_SENDSRCADDR)
+    case SOCKET_OPT_IP_SENDSRCADDR:
+        result = nsetopt_lvl_ip_sendsrcaddr(env, descP, eVal);
+        break;
+#endif
+
 #if defined(IP_TOS)
     case SOCKET_OPT_IP_TOS:
         result = nsetopt_lvl_ip_tos(env, descP, eVal);
@@ -5808,6 +5824,25 @@ ERL_NIF_TERM nsetopt_lvl_ip_router_alert(ErlNifEnv*        env,
 #endif
 
 
+/* nsetopt_lvl_ip_sendsrcaddr - Level IP SENDSRCADDR option
+ */
+#if defined(IP_SENDSRCADDR)
+static
+ERL_NIF_TERM nsetopt_lvl_ip_sendsrcaddr(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_SENDSRCADDR, eVal);
+}
+#endif
+
+
 /* nsetopt_lvl_ip_tos - Level IP TOS option
  */
 #if defined(IP_TOS)
@@ -8418,6 +8453,12 @@ ERL_NIF_TERM ngetopt_lvl_ip(ErlNifEnv*        env,
         break;
 #endif
 
+#if defined(IP_SENDSRCADDR)
+    case SOCKET_OPT_IP_SENDSRCADDR:
+        result = ngetopt_lvl_ip_sendsrcaddr(env, descP);
+        break;
+#endif
+
 #if defined(IP_TOS)
     case SOCKET_OPT_IP_TOS:
         result = ngetopt_lvl_ip_tos(env, descP);
@@ -8846,6 +8887,24 @@ ERL_NIF_TERM ngetopt_lvl_ip_router_alert(ErlNifEnv*        env,
 #endif
 
 
+/* ngetopt_lvl_ip_sendsrcaddr - Level IP SENDSRCADDR option
+ */
+#if defined(IP_SENDSRCADDR)
+static
+ERL_NIF_TERM ngetopt_lvl_ip_sendsrcaddr(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_SENDSRCADDR);
+}
+#endif
+
+
 /* ngetopt_lvl_ip_tos - Level IP TOS option
  */
 #if defined(IP_TOS)
diff --git a/erts/preloaded/ebin/socket.beam b/erts/preloaded/ebin/socket.beam
index 90cb657178..b2bd8f2728 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 68b7d3f4b0..1983c993a5 100644
--- a/erts/preloaded/src/socket.erl
+++ b/erts/preloaded/src/socket.erl
@@ -638,11 +638,11 @@
 -define(SOCKET_OPT_IP_RECVTTL,               26).
 -define(SOCKET_OPT_IP_RETOPTS,               27).
 -define(SOCKET_OPT_IP_ROUTER_ALERT,          28).
-%% -define(SOCKET_OPT_IP_SNDSRCADDR,            29).
+-define(SOCKET_OPT_IP_SENDSRCADDR,           29). % FreeBSD
 -define(SOCKET_OPT_IP_TOS,                   30).
 -define(SOCKET_OPT_IP_TRANSPARENT,           31).
 -define(SOCKET_OPT_IP_TTL,                   32).
--define(SOCKET_OPT_IP_UNBLOCK_SOURCE,           33).
+-define(SOCKET_OPT_IP_UNBLOCK_SOURCE,        33).
 
 -define(SOCKET_OPT_IPV6_ADDRFORM,           1).
 -define(SOCKET_OPT_IPV6_ADD_MEMBERSHIP,     2).
@@ -2316,6 +2316,9 @@ enc_setopt_value(ip, retopts, V, _D, _T, _P)
 enc_setopt_value(ip, router_alert, V, _D, _T, _P)
   when is_integer(V) ->
     V;
+enc_setopt_value(ip, sendsrcaddr, V, _D, _T, _P)
+  when is_boolean(V) ->
+    V;
 enc_setopt_value(ip, tos, V, _D, _T, _P)
   when (V =:= lowdelay)    orelse
        (V =:= throughput)  orelse
@@ -2776,6 +2779,8 @@ enc_sockopt_key(ip = _L, retopts = _Opt, _Dir, _D, T, _P) when (T =/= stream) ->
     ?SOCKET_OPT_IP_RETOPTS;
 enc_sockopt_key(ip, router_alert = _Opt, _Dir, _D, raw = _T, _P) ->
     ?SOCKET_OPT_IP_ROUTER_ALERT;
+enc_sockopt_key(ip, sendsrcaddr = _Opt, _Dir, _D, _T, _P) ->
+    ?SOCKET_OPT_IP_SENDSRCADDR;
 %% On FreeBSD it specifies that this option is only valid
 %% for stream, dgram and "some" raw sockets...
 %% No such condition on linux (in the man page)...