[esock] Finalize handling of Unix Domain Socket

Corrected various issues and added missing stuff.
Default protocol is now indicated with the atom 'default'
instead of the atom 'null'. Also let the underlying OS
decide what protocol is actually the default protocol.

OTP-15822

2 files changed, 55 insertions, 5 deletions

diff --git a/erts/emulator/nifs/common/socket_int.h b/erts/emulator/nifs/common/socket_int.h
index 38c28a6de5..d6977be5aa 100644
--- a/erts/emulator/nifs/common/socket_int.h
+++ b/erts/emulator/nifs/common/socket_int.h
@@ -139,6 +139,7 @@ typedef unsigned int BOOLEAN_T;
     GLOBAL_ATOM_DEF(ctrunc);                   \
     GLOBAL_ATOM_DEF(data);                     \
     GLOBAL_ATOM_DEF(debug);                    \
+    GLOBAL_ATOM_DEF(default);      \
     GLOBAL_ATOM_DEF(default_send_params);      \
     GLOBAL_ATOM_DEF(delayed_ack_time);         \
     GLOBAL_ATOM_DEF(dgram);                    \
diff --git a/erts/emulator/nifs/common/socket_nif.c b/erts/emulator/nifs/common/socket_nif.c
index e71c786d3e..7484694cdb 100644
--- a/erts/emulator/nifs/common/socket_nif.c
+++ b/erts/emulator/nifs/common/socket_nif.c
@@ -528,6 +528,7 @@ typedef union {
 #define SOCKET_TYPE_SEQPACKET     5
 
 /* protocol */
+#define SOCKET_PROTOCOL_DEFAULT   0
 #define SOCKET_PROTOCOL_IP        1
 #define SOCKET_PROTOCOL_TCP       2
 #define SOCKET_PROTOCOL_UDP       3
@@ -1000,6 +1001,8 @@ static ERL_NIF_TERM nopen(ErlNifEnv* env,
                           int        type,
                           int        protocol,
                           char*      netns);
+static BOOLEAN_T nopen_which_protocol(SOCKET sock, int* proto);
+
 static ERL_NIF_TERM nbind(ErlNifEnv*       env,
                           ESockDescriptor* descP,
                           ESockAddress*    sockAddrP,
@@ -2644,6 +2647,7 @@ static char str_exsend[]         = "exsend";     // failed send
     GLOBAL_ATOM_DECL(ctrunc);                          \
     GLOBAL_ATOM_DECL(data);                            \
     GLOBAL_ATOM_DECL(debug);                           \
+    GLOBAL_ATOM_DECL(default);                         \
     GLOBAL_ATOM_DECL(default_send_params);             \
     GLOBAL_ATOM_DECL(delayed_ack_time);                \
     GLOBAL_ATOM_DECL(dgram);                           \
@@ -4421,6 +4425,7 @@ ERL_NIF_TERM nif_open(ErlNifEnv*         env,
  * yet, we must use the global debug flag.
  */
 #if !defined(__WIN32__)
+
 static
 ERL_NIF_TERM nopen(ErlNifEnv* env,
                    int domain, int type, int protocol,
@@ -4428,7 +4433,7 @@ ERL_NIF_TERM nopen(ErlNifEnv* env,
 {
     ESockDescriptor* descP;
     ERL_NIF_TERM     res;
-    int              save_errno = 0;
+    int              proto = protocol, save_errno = 0;
     SOCKET           sock;
     HANDLE           event;
 #ifdef HAVE_SETNS
@@ -4448,11 +4453,24 @@ ERL_NIF_TERM nopen(ErlNifEnv* env,
         return esock_make_error_errno(env, save_errno);
 #endif
 
-    if ((sock = sock_open(domain, type, protocol)) == INVALID_SOCKET)
+    if ((sock = sock_open(domain, type, proto)) == INVALID_SOCKET)
         return esock_make_error_errno(env, sock_errno());
 
     SGDBG( ("SOCKET", "nopen -> open success: %d\r\n", sock) );
 
+
+    /* NOTE that if the protocol = 0 (default) and the domain is not
+     * local (AF_LOCAL) we need to explicitly get the protocol here!
+     */
+    
+    if ((proto != 0) && (domain != AF_LOCAL))
+        if (!nopen_which_protocol(sock, &proto)) {
+            save_errno = sock_errno();
+            while ((sock_close(sock) == INVALID_SOCKET) && (sock_errno() == EINTR));
+            return esock_make_error_errno(env, save_errno);
+        }
+
+
 #ifdef HAVE_SETNS
     if ((netns != NULL) &&
         !restore_network_namespace(current_ns, sock, &save_errno))
@@ -4484,7 +4502,7 @@ ERL_NIF_TERM nopen(ErlNifEnv* env,
     descP->state    = SOCKET_STATE_OPEN;
     descP->domain   = domain;
     descP->type     = type;
-    descP->protocol = protocol;
+    descP->protocol = proto;
 
     /* Does this apply to other types? Such as RAW?
      * Also, is this really correct? Should we not wait for bind?
@@ -4521,6 +4539,26 @@ ERL_NIF_TERM nopen(ErlNifEnv* env,
 
     return esock_make_ok2(env, res);
 }
+
+
+static
+BOOLEAN_T nopen_which_protocol(SOCKET sock, int* proto)
+{
+    int          val;
+    SOCKOPTLEN_T valSz = sizeof(val);
+    int          res;
+
+    res = sock_getopt(sock, SOL_SOCKET, SO_PROTOCOL, &val, &valSz);
+
+    if (res != 0) {
+        return FALSE;
+    } else {
+        *proto = val;
+        return TRUE;
+    }
+}
+
+
 #endif // if !defined(__WIN32__)
 
 
@@ -10895,7 +10933,11 @@ ERL_NIF_TERM ngetopt_otp_protocol(ErlNifEnv*       env,
 
         switch (val) {
         case IPPROTO_IP:
-            result = esock_make_ok2(env, esock_atom_ip);
+            if (descP->domain == AF_LOCAL) {
+                result = esock_make_ok2(env, esock_atom_default);
+            } else {
+                result = esock_make_ok2(env, esock_atom_ip);
+            }
             break;
 
         case IPPROTO_TCP:
@@ -11467,7 +11509,10 @@ ERL_NIF_TERM ngetopt_lvl_sock_protocol(ErlNifEnv*       env,
     } else {
         switch (val) {
         case IPPROTO_IP:
-            result = esock_make_ok2(env, esock_atom_ip);
+            if (descP->domain == AF_LOCAL)
+                result = esock_make_ok2(env, esock_atom_default);
+            else
+                result = esock_make_ok2(env, esock_atom_ip);
             break;
 
         case IPPROTO_TCP:
@@ -17039,6 +17084,10 @@ BOOLEAN_T eproto2proto(ErlNifEnv*   env,
         }
 
         switch (ep) {
+        case SOCKET_PROTOCOL_DEFAULT:
+            *proto = 0; // default - note that _IP also has the value 0...
+            break;
+            
         case SOCKET_PROTOCOL_IP:
             *proto = IPPROTO_IP;
             break;