6loWPAN: A little HC1 compression logic.

net/sixlowpan/sixlowpan_hc06.c

@@ -203,7 +203,10 @@ void sixlowpan_hc06_initialize(void)
  *
  * Input Parameters:
  *   ieee     - A reference to the IEE802.15.4 network device state
- *   destaddr - L2 destination address, needed to compress IP dest
+ *   ipv6     - The IPv6 header to be compressed
+ *   destaddr - L2 destination address, needed to compress the IP
+ *              destination field
+ *   iob      - The IOB into which the compressed header should be saved.
  *
  * Returned Value:
  *   None

net/sixlowpan/sixlowpan_hc1.c

@@ -114,8 +114,10 @@
  *
  * Input Parmeters:
  *   ieee     - A reference to the IEE802.15.4 network device state
+ *   ipv6     - The IPv6 header to be compressed
  *   destaddr - L2 destination address, needed to compress the IP
  *              destination field
+ *   iob      - The IOB into which the compressed header should be saved.
  *
  * Returned Value:
  *   None
@@ -123,9 +125,109 @@
  ****************************************************************************/
 
 void sixlowpan_compresshdr_hc1(FAR struct ieee802154_driver_s *ieee,
-                               FAR struct rimeaddr_s *destaddr)
+                               FAR const struct ipv6_hdr_s *ipv6,
+                               FAR const struct rimeaddr_s *destaddr,
+                               FAR struct iob_s *iob)
 {
-/* REVISIT: To be provided */
+  FAR uint8_t *hc1 = RIME_HC1_PTR;
+
+  /* Check if all the assumptions for full compression are valid */
+
+  if (ipv6->vtc != 0x60 || ipv6->tcflow != 0 || ipv6->flow != 0 ||
+      !sixlowpan_islinklocal(&ipv6->srcipaddr) ||
+      !sixlowpan_ismacbased(&ipv6->srcipaddr, &ieee->i_rimeaddr) ||
+      !sixlowpan_islinklocal(&ipv6->destipaddr) ||
+      !sixlowpan_ismacbased(&ipv6->destipaddr, destaddr) ||
+      (ipv6->proto != IP_PROTO_ICMP6 && ipv6->proto != IP_PROTO_UDP &&
+       ipv6->proto != IP_PROTO_TCP))
+    {
+      /* IPV6 DISPATCH
+       * Something cannot be compressed, use IPV6 DISPATCH,
+       * compress nothing, copy IPv6 header in rime buffer
+       */
+
+      *g_rimeptr      = SIXLOWPAN_DISPATCH_IPV6;
+       g_rime_hdrlen += SIXLOWPAN_IPV6_HDR_LEN;
+       memcpy(g_rimeptr + g_rime_hdrlen, ipv6, IPv6_HDRLEN);
+       g_rime_hdrlen += IPv6_HDRLEN;
+       g_uncomp_hdrlen += IPv6_HDRLEN;
+    }
+  else
+    {
+      /* HC1 DISPATCH  maximum compresssion:
+       * All fields in the IP header but Hop Limit are elided.  If next
+       * header is UDP, we compress UDP header using HC2
+       */
+
+      hc1[RIME_HC1_DISPATCH] = SIXLOWPAN_DISPATCH_HC1;
+      g_uncomp_hdrlen += IPv6_HDRLEN;
+      switch (ipv6->proto)
+        {
+        case IP_PROTO_ICMP6:
+          /* HC1 encoding and ttl */
+
+          hc1[RIME_HC1_ENCODING] = 0xfc;
+          hc1[RIME_HC1_TTL] = ipv6->ttl;
+          g_rime_hdrlen += SIXLOWPAN_HC1_HDR_LEN;
+          break;
+
+#if CONFIG_NET_TCP
+        case IP_PROTO_TCP:
+          /* HC1 encoding and ttl */
+
+          hc1[RIME_HC1_ENCODING] = 0xfe;
+          hc1[RIME_HC1_TTL] = ipv6->ttl;
+          g_rime_hdrlen += SIXLOWPAN_HC1_HDR_LEN;
+          break;
+#endif /* CONFIG_NET_TCP */
+
+#if CONFIG_NET_UDP
+        case IP_PROTO_UDP:
+          FAR struct udp_hdr_s *udp = UDPIPv6BUF(dev);
+
+          /* Try to compress UDP header (we do only full compression).  This
+           * is feasible if both src and dest ports are between
+           * SIXLOWPAN_UDP_PORT_MIN and SIXLOWPAN_UDP_PORT_MIN + 15
+           */
+
+          ninfo("local/remote port %u/%u\n", udp->srcport, udp->destport);
+
+          if (htons(udp->srcport)  >= SIXLOWPAN_UDP_PORT_MIN &&
+              htons(udp->srcport)  <  SIXLOWPAN_UDP_PORT_MAX &&
+              htons(udp->destport) >= SIXLOWPAN_UDP_PORT_MIN &&
+              htons(udp->destport) <  SIXLOWPAN_UDP_PORT_MAX)
+            {
+              FAR uint8_t *hcudp = RIME_HC1_HC_UDP_PTR;
+
+              /* HC1 encoding */
+
+              hcudp[RIME_HC1_HC_UDP_HC1_ENCODING] = 0xfb;
+
+              /* HC_UDP encoding, ttl, src and dest ports, checksum */
+
+              hcudp[RIME_HC1_HC_UDP_UDP_ENCODING] = 0xe0;
+              hcudp[RIME_HC1_HC_UDP_TTL]          = ipv6->ttl;
+              hcudp[RIME_HC1_HC_UDP_PORTS]        =
+                (uint8_t)((htons(udp->srcport) - SIXLOWPAN_UDP_PORT_MIN) << 4) +
+                (uint8_t)((htons(udp->destport) - SIXLOWPAN_UDP_PORT_MIN));
+
+              memcpy(&hcudp[RIME_HC1_HC_UDP_CHKSUM], &udp->udpchksum, 2);
+
+              g_rime_hdrlen   += SIXLOWPAN_HC1_HC_UDP_HDR_LEN;
+              g_uncomp_hdrlen += UIP_UDPH_LEN;
+            }
+          else
+            {
+              /* HC1 encoding and ttl */
+
+              hc1[RIME_HC1_ENCODING] = 0xfa;
+              hc1[RIME_HC1_TTL]      = ipv6->ttl;
+              g_rime_hdrlen         += SIXLOWPAN_HC1_HDR_LEN;
+            }
+          break;
+#endif /* CONFIG_NET_UDP */
+        }
+    }
 }
 
 /****************************************************************************

net/sixlowpan/sixlowpan_internal.h

@@ -228,7 +228,7 @@
 /* General helper macros ****************************************************/
 
 #define GETINT16(ptr,index) \
-  ((((uint16_t)((ptr)[index]) << 8)) | ((uint16_t)(((ptr)[(index) + 1]))))
+  ((((uint16_t)((ptr)[index])) << 8) | ((uint16_t)(((ptr)[(index) + 1]))))
 #define PUTINT16(ptr,index,value) \
   do \
     { \
@@ -396,6 +396,7 @@ extern struct rimeaddr_s g_pktaddrs[PACKETBUF_NUM_ADDRS];
 
 struct net_driver_s;         /* Forward reference */
 struct ieee802154_driver_s;  /* Forward reference */
+struct ipv6_hdr_s;           /* Forward reference */
 struct rimeaddr_s;           /* Forward reference */
 struct iob_s;                /* Forward reference */
 
@@ -559,7 +560,10 @@ void sixlowpan_hc06_initialize(void);
  *
  * Input Parameters:
  *   ieee     - A reference to the IEE802.15.4 network device state
- *   destaddr - L2 destination address, needed to compress IP dest
+ *   ipv6     - The IPv6 header to be compressed
+ *   destaddr - L2 destination address, needed to compress the IP
+ *              destination field
+ *   iob      - The IOB into which the compressed header should be saved.
  *
  * Returned Value:
  *   None
@@ -567,8 +571,10 @@ void sixlowpan_hc06_initialize(void);
  ****************************************************************************/
 
 #ifdef CONFIG_NET_6LOWPAN_COMPRESSION_HC06
-void sixlowpan_compresshdr_hc06(FAR struct ieee802154_driver_s *dev,
+void sixlowpan_compresshdr_hc06(FAR struct ieee802154_driver_s *ieee,
-                                FAR struct rimeaddr_s *destaddr);
+                                FAR const struct ipv6_hdr_s *ipv6,
+                                FAR const struct rimeaddr_s *destaddr,
+                                FAR struct iob_s *iob);
 #endif
 
 /****************************************************************************
@@ -612,8 +618,10 @@ void sixlowpan_uncompresshdr_hc06(FAR struct ieee802154_driver_s *ieee,
  *
  * Input Parmeters:
  *   ieee     - A reference to the IEE802.15.4 network device state
+ *   ipv6     - The IPv6 header to be compressed
  *   destaddr - L2 destination address, needed to compress the IP
  *              destination field
+ *   iob      - The IOB into which the compressed header should be saved.
  *
  * Returned Value:
  *   None
@@ -622,7 +630,9 @@ void sixlowpan_uncompresshdr_hc06(FAR struct ieee802154_driver_s *ieee,
 
 #ifdef CONFIG_NET_6LOWPAN_COMPRESSION_HC1
 void sixlowpan_compresshdr_hc1(FAR struct ieee802154_driver_s *ieee,
-                               FAR struct rimeaddr_s *destaddr);
+                               FAR const struct ipv6_hdr_s *ipv6,
+                               FAR const struct rimeaddr_s *destaddr,
+                               FAR struct iob_s *iob);
 #endif
 
 /****************************************************************************
@@ -664,26 +674,34 @@ void sixlowpan_uncompresshdr_hc1(FAR struct ieee802154_driver_s *ieee,
 int sixlowpan_frame_hdralloc(FAR struct iob_s *iob, int size);
 
 /****************************************************************************
- * Name: sixlowpan_ipfromrime and sixlowpan_rimefromip
+ * Name: sixlowpan_islinklocal, sixlowpan_ipfromrime, sixlowpan_rimefromip,
+ *       and sixlowpan_ismacbased
  *
  * Description:
- *   sixlowpan_ipfromrime: Use stateless auto-configuration to create an IP
+ *   sixlowpan_ipfromrime: Create a link local IPv6 address from a rime 
- *   address from a rime address.
+ *   address.
  *
- *   sixlowpan_rimefromip: Assume stateless auto-configuration to extrate
+ *   sixlowpan_rimefromip: Extract the rime address from a link local IPv6
- *   the rime address from an IP address
+ *   address.
+ *
+ *   sixlowpan_islinklocal and sixlowpan_ismacbased will return true for
+ *   address created in this fashion.
  *
  *    128  112  96   80    64   48   32   16
  *    ---- ---- ---- ----  ---- ---- ---- ----
- *    fe80 0000 0000 0000  xxxx xxxx 0000 0000 2-byte Rime address (VALID?)
+ *    fe80 0000 0000 0000  xxxx 0000 0000 0000 2-byte Rime address (VALID?)
  *    fe80 0000 0000 0000  xxxx xxxx xxxx xxxx 8-byte Rime address
  *
  ****************************************************************************/
 
+#define sixlowpan_islinklocal(ipaddr) ((ipaddr)[0] = NTOHS(0xfe80))
+
 void sixlowpan_ipfromrime(FAR const struct rimeaddr_s *rime,
                           net_ipv6addr_t ipaddr);
 void sixlowpan_rimefromip(const net_ipv6addr_t ipaddr,
                           FAR struct rimeaddr_s *rime);
+bool sixlowpan_ismacbased(const net_ipv6addr_t ipaddr,
+                          FAR const struct rimeaddr_s *rime);
 
 #endif /* CONFIG_NET_6LOWPAN */
 #endif /* _NET_SIXLOWPAN_SIXLOWPAN_INTERNAL_H */

net/sixlowpan/sixlowpan_utils.c

@@ -103,8 +103,7 @@ int sixlowpan_frame_hdralloc(FAR struct iob_s *iob, int size)
  * Name: sixlowpan_ipfromrime
  *
  * Description:
- *   Use stateless auto-configuration to create an IP address from a rime
+ *   Create a link local IPv6 address from a rime address:
- *   address:
  *
  *    128  112  96   80    64   48   32   16
  *    ---- ---- ---- ----  ---- ---- ---- ----
@@ -129,18 +128,18 @@ void sixlowpan_ipfromrime(FAR const struct rimeaddr_s *rime,
    */
 
   memcpy(&ipaddr[4], rime, CONFIG_NET_6LOWPAN_RIMEADDR_SIZE);
+  ipaddr[4] ^= 0x0200;
 }
 
 /****************************************************************************
  * Name: sixlowpan_rimefromip
  *
  * Description:
- *   Assume stateless auto-configuration to extrate the rime address from
+ *   Extract the rime address from a link local IPv6 address:
- *   an IP address:
  *
  *    128  112  96   80    64   48   32   16
  *    ---- ---- ---- ----  ---- ---- ---- ----
- *    fe80 0000 0000 0000  xxxx xxxx 0000 0000 2-byte Rime address (VALID?)
+ *    fe80 0000 0000 0000  xxxx 0000 0000 0000 2-byte Rime address (VALID?)
  *    fe80 0000 0000 0000  xxxx xxxx xxxx xxxx 8-byte Rime address
  *
  ****************************************************************************/
@@ -153,6 +152,36 @@ void sixlowpan_rimefromip(const net_ipv6addr_t ipaddr,
   DEBUGASSERT(ipaddr[0] == 0xfe80);
 
   memcpy(rime, &ipaddr[4], CONFIG_NET_6LOWPAN_RIMEADDR_SIZE);
+  rime->u8[0] ^= 0x02;
+}
+
+/****************************************************************************
+ * Name: sixlowpan_ismacbased
+ *
+ * Description:
+ *   Extract the rime address from a link local IPv6 address:
+ *
+ *    128  112  96   80    64   48   32   16
+ *    ---- ---- ---- ----  ---- ---- ---- ----
+ *    fe80 0000 0000 0000  xxxx 0000 0000 0000 2-byte Rime address (VALID?)
+ *    fe80 0000 0000 0000  xxxx xxxx xxxx xxxx 8-byte Rime address
+ *
+ ****************************************************************************/
+
+bool sixlowpan_ismacbased(const net_ipv6addr_t ipaddr,
+                          FAR const struct rimeaddr_s *rime)
+{
+  FAR const uint8_t *rimeptr = rime->u8;
+
+#if CONFIG_NET_6LOWPAN_RIMEADDR_SIZE == 2
+  return ((ipaddr[4] == (GETINT16(rimeptr, 0) ^ 0x0200)) &&
+           ipaddr[5] == 0 && ipaddr[6] == 0 && ipaddr[7] == 0);
+#else /* CONFIG_NET_6LOWPAN_RIMEADDR_SIZE == 8 */
+  return ((ipaddr[4] == (GETINT16(rimeptr, 0) ^ 0x0200)) &&
+           ipaddr[5] == GETINT16(rimeptr, 2) &&
+           ipaddr[6] == GETINT16(rimeptr, 4) &&
+           ipaddr[7] == GETINT16(rimeptr, 6));
+#endif
 }
 
 #endif /* CONFIG_NET_6LOWPAN */