adding comments here and there

coppino-main.ino

@@ -3,6 +3,7 @@
 #include "slip.h"
 #include "udp.h"
 
+/* an UDP application, which simply replies HELLO-WORLD-UDP */
 int udp_server(char* output_buffer, const char* input_buffer, int len) {
   const char msg[] = "HELLO-WORLD-UDP\n";
   digitalWrite(13, !digitalRead(13));
@@ -12,10 +13,25 @@ int udp_server(char* output_buffer, const char* input_buffer, int len) {
 
 void setup() {
   pinMode(13, OUTPUT);
-  
-  Serial.begin(19200);
-  memcpy(&coppino::address, "\x20\x01\x04\x70\xc8\x44\x00\x31\x00\x00\x00\x00\x00\x00\xca\xfe", 16);
 
+  /* setup serial for Internet connectivity
+   * attach a SLIP daemon on the other endpoint; a good one is `tunslip6` by Contiki
+   * $ tunslip6 -s /dev/ttyUSB0 -L -v5 -B 19200 2001:db8:1324::1/64
+   * Note: the address given is the one on the host it is running on
+  */
+  Serial.begin(19200);
+
+  /* set unique identifier of network hardware. It MUST be unique!
+   * For example, this could be your microcontroller serial number
+   * Note: pay attention to enter exactly 64 bits / 8 bytes
+  */
+  ipv6::setEUI("\xde\xad\xbe\xef\x12\x34\x56\x78");
+  /* enable or disable IPv6 Stateless Auto-Configuration (SLAAC) */
+  ipv6::SLAAC(false);
+  /* set global address -- will be overwritten if SLAAC is enabled and a Router Advertisement is received */
+  ipv6::setGlobalAddress("\x20\x01\x04\x70\xc8\x44\x00\x31\x00\x00\x00\x00\x00\x00\xca\xfe");
+
+  /* start a server un UDP port 80 */
   udp::set_handler(80, udp_server);
 }
 

coppino.h

@@ -5,12 +5,6 @@
 
 namespace coppino {
   const uint8_t LEN = 128;
-  extern ipv6::IPv6Addr address;
-  /* netmask:
-  *  no netmask is needed, because everything is sent over TTL UART
-  * gateway:
-  *  the same as above
-  */
 
   void handler(void);
   void hexdump(const char* pointer, int len);

coppino.ino

@@ -1,8 +1,6 @@
 #include "coppino.h"
 
 namespace coppino {
-  ipv6::IPv6Addr address;
-
   void handler() {
     int r;
     

ipv6.h

@@ -2,17 +2,18 @@
 #define COPPINO_IPV6_H
 
 namespace ipv6 {
-
+  /* maximum length for an IPv6 packet */
   const uint8_t LEN = 128;
+
+  /* ICMP Types */
   const uint8_t ICMP_ECHO_REQUEST_TYPE = 128;
   const uint8_t ICMP_ECHO_REPLY_TYPE   = 129;
   const uint8_t ICMP_RADV_TYPE         = 134;
 
+  /* Next-Header Types */
   const uint8_t NH_ICMP = 58;
   const uint8_t NH_UDP  = 17;
 
-  extern uint8_t HOP_LIMIT;
-
   class IPv6Addr {
     private:
       char address[16];
@@ -21,18 +22,8 @@ namespace ipv6 {
       IPv6Addr(const char* address);
   };
 
-  extern const IPv6Addr LINK_LOCAL_ADDRESS;
   extern const IPv6Addr ALL_NODES_ADDRESS;
 
-  struct ipv6_packet_header {
-    char field[4];
-    char len[2];
-    char next_header;
-    char hop_limit;
-    IPv6Addr src_addr;
-    IPv6Addr dst_addr;
-  }__attribute__((packed));
-
   class IPv6Packet {
     private:
       char packet[LEN];
@@ -53,6 +44,7 @@ namespace ipv6 {
       void doAction();
   };
 
+  /* incoming and outgoing packets buffer */
   extern IPv6Packet packetin;
   extern IPv6Packet packetout;
 
@@ -69,6 +61,7 @@ namespace ipv6 {
     int len                   /* IPv6 payload length */
    );
 
+  /* RFC 4861 -- begin */
   struct ICMPv6_RADV {
     uint8_t type;
     uint8_t code;
@@ -95,6 +88,11 @@ namespace ipv6 {
     uint32_t reserved2;
     char prefix[16];
   };
+  /* RFC 4861 -- end */
+
+  void setEUI(const char* eui);         /* 64bit Extended Unique Identifier */
+  void SLAAC(bool enable);              /* enable IPv6 automatic prefix configuration (listens for RADV) */
+  void setGlobalAddress(const char* address); /* global IPv6 address, manually configured */
 }
 
 #endif

ipv6.ino

@@ -4,16 +4,30 @@
 namespace ipv6 {
 /******** costants ********/
 const IPv6Addr  ALL_NODES_ADDRESS("\xff\x02\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01");  /* ff02::1 */
-const IPv6Addr LINK_LOCAL_ADDRESS("\xfe\x80\x00\x00\x00\x00\x00\x00\xde\xad\xbe\xef\x12\x34\x56\x78");  /* fe80::dead:beef:1234:5678 */ /* TODO */
 
 /******** variables ********/
 uint8_t HOP_LIMIT = 64;
+IPv6Addr LINK_LOCAL_ADDRESS;
+IPv6Addr GLOBAL_ADDRESS;
+bool slaac_enable;
 
-/******** buffer ********/
+/******** buffers ********/
 IPv6Packet packetin;
 IPv6Packet packetout;
 
 /******** FUNCTIONS *******/
+void setEUI(const char* eui) {
+  memset(&LINK_LOCAL_ADDRESS, 0, 16);
+  memcpy(&LINK_LOCAL_ADDRESS, "\xfe\x80", 2);
+  memcpy( ((char*)&LINK_LOCAL_ADDRESS) + 8 , eui, 8);
+}
+void SLAAC(bool enable) {
+  slaac_enable = enable;
+}
+void setGlobalAddress(const char* address) {
+  memcpy(&GLOBAL_ADDRESS, address, 16);
+}
+
 uint16_t compute_checksum(const IPv6Addr* src_addr, const IPv6Addr* dst_addr, uint8_t next_header, int upper_len, const char* payload, int len) {
   char buffer[LEN];
   uint32_t total;
@@ -120,7 +134,7 @@ void IPv6Packet::doAction() {
   if (
     (memcmp(&(ALL_NODES_ADDRESS), packet + 24, 16) == 0) ||
     (memcmp(&(LINK_LOCAL_ADDRESS), packet + 24, 16) == 0) ||
-    (memcmp(&(coppino::address), packet + 24, 16) == 0)) {
+    (memcmp(&(GLOBAL_ADDRESS), packet + 24, 16) == 0)) {
     int ilen = this->getLen();  /* input payload length */
     int olen;                   /* output payload length */
     
@@ -149,9 +163,12 @@ void IPv6Packet::doAction() {
         /* no other protocols are known here, sorry :-) */
         break;
     }
-  }
+  } /* ...else discard packet */
 }
 
+/* handles ICMP and (possibly) generate a reply
+ *  returns length of generated packet (written to output_buffer), or -1 if there is no reply packet
+*/
 int handleICMP(char* output_buffer, const char* input_buffer, int len) {
   uint8_t type = *(input_buffer);
 
@@ -190,7 +207,7 @@ int handleICMP(char* output_buffer, const char* input_buffer, int len) {
     memcpy(output_buffer + 2, &checksum, 2);
     return len;
     
-  } else if (type == ICMP_RADV_TYPE) {  /* if it is IVMPc6 Router Advertisement, then... */
+  } else if (type == ICMP_RADV_TYPE && slaac_enable) {  /* if it is IVMPc6 Router Advertisement, then... */
     ICMPv6_RADV* radv = (ICMPv6_RADV*)input_buffer;
     HOP_LIMIT = (radv->cur_hop_limit != 0) ? radv->cur_hop_limit : 64;
     
@@ -198,13 +215,12 @@ int handleICMP(char* output_buffer, const char* input_buffer, int len) {
       ICMPv6_RADV_Option* option = (ICMPv6_RADV_Option*) (radv + 1);
       option != input_buffer + len;
       option = (ICMPv6_RADV_Option*) ( ((char*)(option)) + option->len )) {
-        digitalWrite(13, !digitalRead(13));
         if (option->type == 3 && option->len == 4) {  /* if it is a ICMPv6 Prefix Information, then... */
           ICMPv6_RADV_PrefixInformation* p = (ICMPv6_RADV_PrefixInformation*) option;
           
           if (p->prefix_length != 64) continue; /* only /64 prefix is supported */
           if (! (p->la_flags & 0x40)) continue; /* only SLAAC is supported */
-          memcpy(&coppino::address, p->prefix, 8); /* set prefix -- leave host bits unchanged */
+          memcpy(&GLOBAL_ADDRESS, p->prefix, 8); /* set prefix -- leave host bits unchanged */
           break;
         }
     }

slip.ino

@@ -49,8 +49,6 @@ namespace slip {
         }
       }
     }
-
-
     
     return i;
   }