add a bfew (pretty general) notes about lwres protocol

doc/design/lwres

@@ -0,0 +1,80 @@
+$Id: lwres,v 1.1 2000/02/29 20:10:49 explorer Exp $
+
+General design:
+
+The lwres library converts structures into wire-format packets for
+transmission, and unmarshalls them on receive.
+
+
+Marshalling and unmarshalling:
+
+Each structure will have two functions defined, one to take a
+wire-format packet and convert it into a structure, and another to
+take a structure and convert it into a wire-format packet.  There
+is a structure cleanup function that will take the unmarshalled
+structure and free any dynamically allocated elements.
+
+
+Wire formats:
+
+All integer values are in network byte order.
+
+All addresses are in network byte order.  That is, they are directly
+usable and do not need to be byte swapped, at least for ipv4 and ipv6.
+
+All character strings are prefixed with a length, and are NUL
+terminated C strings.  This is a concession for structure handling on
+the receive side, and allows a mapping structure to point to data
+contained in the actual receive buffer, eliminating copying.
+
+
+NOOP (aka ping) packet format:
+
+	lwres_lwpacket_t header;
+	isc_uint16_t datalength;
+	< datalength bytes >
+
+The server simply returns the entire data region in the reply.  This
+allows the client to determine if the server is operational.
+
+
+GETADDRSBYNAME:
+
+	lwres_lwpacket_t header;
+
+	isc_uint16_t naliases;
+
+	isc_uint16_t naddrs;
+
+	isc_uint16_t real_name_len;
+	< real_name_len bytes of name >
+	isc_uint8_t \0
+
+	< naliases of
+		isc_uint16_t len;
+		< len bytes of name >
+		isc_uint8_t \0
+	>
+
+	< naddrs of
+		isc_uint32_t family;
+		isc_uint16_t len;
+		< len bytes of address >
+	>
+
+
+GETNAMEBYADDR:
+
+	lwres_lwpacket_t header;
+
+	isc_uint16_t naliases;
+
+	isc_uint16_t real_name_len;
+	< real_name_len bytes of name >
+	isc_uint8_t \0
+
+	< naliases of
+		isc_uint16_t len;
+		< len bytes of name >
+		isc_uint8_t \0
+	>