IEEE 802.15.4/6LoWPAN: Correct one more usage of saddr; also update a README and the TODO list.

TODO

@@ -1260,7 +1260,7 @@ o Network (net/, drivers/net)
                implementation.
 
                If we want to use IPv6 neighbor discovery, we could dispense
-               with the all MAC  based addressing.  But if we want to retain
+               with the all MAC based addressing.  But if we want to retain
                the more compact MAC-based addressing, then we don't need
                IPv6 neighbor discovery.
 

net/sixlowpan/README.txt

@@ -3,16 +3,41 @@
 
 The current 6LoWPAN implementation uses only link local, MAC-based
 addressing addressing (as discussed in more detail below).  Thus if you know
-the node addressing, then you know the IPv6 address (and vice-versa)
+the node addressing, then you know the IPv6 address (and vice-versa).
+
+As a configuration option, the 6LoWPAN implementation will use either the
+node's 2-byte short address or 8-byte extended address as the MAC address
+that the IPv6 address is based on.  This is determined by the configuration
+setting CONFIG_NET_6LOWPAN_EXTENDEDADDR.  By default, the 2-byte short
+address is used for the IEEE802.15.4 MAC device's link layer address.  If
+this option is selected, then an 8-byte extended address will be used,
+instead.
+
+All nodes operating on a network have unique, 8-byte extended address,
+that was assigned before the network is configured.  6LoWPAN will use
+either the extended address for direct communication within the PAN or
+the short 2-byte address.  The short 2-byte address, however, is allocated
+by the PAN coordinator when the device associated.  If short addresses are
+used, the network cannot be brought up until is is associated.
+
+Node addressing is modified through IOCTL calls from application logic.
+The network must be in the DOWN state when ever the node addressing is
+modified.  The modified node addresses will have no effect on the reported
+IPv6 address until the network is brought to the UP state.  The new IPv6
+MAC-based addresses are only instantiated when the network transitions
+from the DOWN to UP state.
+
+IPv6 Neighbor Discovery
+-----------------------
 
 IPv6 Neighbor Discovery is not supported.  The current ICMPv6 and neighbor-
-related logic only works with               Ethernet MAC.  For 6LoWPAN, a
+related logic only works with Ethernet MAC.  For 6LoWPAN, a new more
-new more conservative IPv6 neigbor discovery is provided by RFC 6775 which
+conservative IPv6 neigbor discovery is provided by RFC 6775 which is not
-is not currently suppored.  With IPv6 neighbor discovery, any IPv6 address
+currently supported.  With IPv6 neighbor discovery, any IPv6 address may be
-may be associated with any short or extended address.  In fact, that is the
+associated with any short or extended address.  In fact, that is the whole
-whole purpose of the neighbor discover logic:  It plays the same role as ARP
+purpose of the neighbor discover logic:  It plays the same role as ARP in
-in IPv4; it ultimately just manages a neighbor table that, like the arp
+IPv4; it ultimately just manages a neighbor table that, like the arp table,
-table, provides the mapping between IP addresses and node addresses.
+provides the mapping between IP addresses and node addresses.
 
 The NuttX, Contiki-based 6LoWPAN implementation circumvents  the need for
 the neighbor discovery logic by using only MAC-based addressing, i.e., the

wireless/ieee802154/mac802154_netdev.c

@@ -276,6 +276,8 @@ static int macnet_advertise(FAR struct net_driver_s *dev)
     }
 
 #else
+  uint8_t *saddr;
+
   /* Get the saddr from the MAC */
 
   memcpy(arg.ifr_name, dev->d_ifname, IFNAMSIZ);
@@ -289,15 +291,8 @@ static int macnet_advertise(FAR struct net_driver_s *dev)
     }
   else
     {
-      union
+      saddr = arg.u.getreq.attrval.mac.saddr;
-      {
+      IEEE802154_SADDRCOPY(dev->d_mac.ieee802154.u8, saddr);
-        uint16_t u16;
-        uint8_t  u8[2];
-      } u;
-
-      u.u16 = arg.u.getreq.attrval.mac.saddr;
-      dev->d_mac.ieee802154.u8[0] = u.u8[0];
-      dev->d_mac.ieee802154.u8[1] = u.u8[1];
 
       /* Set the IP address based on the saddr */
 
@@ -308,7 +303,7 @@ static int macnet_advertise(FAR struct net_driver_s *dev)
       dev->d_ipv6addr[4]  = 0;
       dev->d_ipv6addr[5]  = HTONS(0x00ff);
       dev->d_ipv6addr[6]  = HTONS(0xfe00);
-      dev->d_ipv6addr[7]  = u.u16;
+      dev->d_ipv6addr[7]  = (uint16_t)saddr[0] << 8 |  (uint16_t)saddr[1];
       dev->d_ipv6addr[7] ^= 0x200;
       return OK;
     }