Bind/Connect: Fallback to IPv4 if IPv6 is not available.

When the family is not specificed we first try an IPv6 address but in
this case we don't want to fail if IPv6 is not supported/activated on
the interface. We want to gracefully fallback to IPv4.

eng/toolchain/aws#50

Author: TurboGit

config/src/aws-net-std__gnat.adb

@@ -152,9 +152,16 @@ package body AWS.Net.Std is
 
             exception
                when E : Sockets.Socket_Error | Sockets.Host_Error =>
-                  if Socket.S.FD /= Sockets.No_Socket then
-                     Sockets.Close_Socket (Socket.S.FD);
-                     Socket.S.FD := Sockets.No_Socket;
+                  --  We don't want to fail if Family_Unspec is specified and
+                  --  we try to bind to an IPv6 address. In this case we want
+                  --  to fallback to IPv4 is possible.
+                  if Family /= Family_Unspec
+                    or else Addr_Info.Addr.Family /= Sockets.Family_Inet6
+                  then
+                     if Socket.S.FD /= Sockets.No_Socket then
+                        Sockets.Close_Socket (Socket.S.FD);
+                        Socket.S.FD := Sockets.No_Socket;
+                     end if;
                   end if;
 
                   Exceptions.Save_Occurrence (Keep_Excp, E);
@@ -289,9 +296,16 @@ package body AWS.Net.Std is
 
             exception
                when E : Sockets.Socket_Error | Sockets.Host_Error =>
-                  if Close_On_Exception then
-                     Sockets.Close_Socket (Socket.S.FD);
-                     Close_On_Exception := False;
+                  --  We don't want to fail if Family_Unspec is specified and
+                  --  we try to bind to an IPv6 address. In this case we want
+                  --  to fallback to IPv4 is possible.
+                  if Family /= Family_Unspec
+                    or else Addr_Info.Addr.Family /= Sockets.Family_Inet6
+                  then
+                     if Close_On_Exception then
+                        Sockets.Close_Socket (Socket.S.FD);
+                        Close_On_Exception := False;
+                     end if;
                   end if;
 
                   Save_Occurrence (Keep_Excp, E);