nat64: Handle IPv6 addresses using "Well-Known Prefix" 64:ff9b::/96

Author: uknoblic

core/net/ip/ip64-addr.c

@@ -36,6 +36,61 @@
 
 #define printf(...)
 /*---------------------------------------------------------------------------*/
+static int
+ip64_addr_ipv4_is_private(const uip_ip4addr_t *ipv4addr)
+{
+  uip_ipaddr_t ipaddr, mask;
+
+  /* 10.0.0.0/8 */
+  uip_ipaddr(&ipaddr, 10, 0, 0, 0);
+  uip_ipaddr(&mask, 255, 0, 0, 0);
+  if(uip_ipaddr_maskcmp(ipv4addr, &ipaddr, &mask)) {
+    return 1;
+  }
+
+  /* 172.16.0.0/12 */
+  uip_ipaddr(&ipaddr, 172, 16, 0, 0);
+  uip_ipaddr(&mask, 255, 240, 0, 0);
+  if(uip_ipaddr_maskcmp(ipv4addr, &ipaddr, &mask)) {
+    return 1;
+  }
+
+  /* 198.18.0.0/15 */
+  uip_ipaddr(&ipaddr, 198, 18, 0, 0);
+  uip_ipaddr(&mask, 255, 254, 0, 0);
+  if(uip_ipaddr_maskcmp(ipv4addr, &ipaddr, &mask)) {
+    return 1;
+  }
+
+  /* 192.168.0.0/16 */
+  uip_ipaddr(&ipaddr, 192, 168, 0, 0);
+  uip_ipaddr(&mask, 255, 255, 0, 0);
+  if(uip_ipaddr_maskcmp(ipv4addr, &ipaddr, &mask)) {
+    return 1;
+  }
+
+  /* 192.0.2.0/24 */
+  uip_ipaddr(&ipaddr, 192, 0, 2, 0);
+  uip_ipaddr(&mask, 255, 255, 255, 0);
+  if(uip_ipaddr_maskcmp(ipv4addr, &ipaddr, &mask)) {
+    return 1;
+  }
+
+  /* 198.51.100.0/24 */
+  uip_ipaddr(&ipaddr, 198, 51, 100, 0);
+  if(uip_ipaddr_maskcmp(ipv4addr, &ipaddr, &mask)) {
+    return 1;
+  }
+
+  /* 203.0.113.0/24 */
+  uip_ipaddr(&ipaddr, 203, 0, 113, 0);
+  if(uip_ipaddr_maskcmp(ipv4addr, &ipaddr, &mask)) {
+    return 1;
+  }
+
+  return 0;
+}
+/*---------------------------------------------------------------------------*/
 void
 ip64_addr_copy4(uip_ip4addr_t *dest, const uip_ip4addr_t *src)
 {
@@ -50,7 +105,7 @@ ip64_addr_copy6(uip_ip6addr_t *dest, const uip_ip6addr_t *src)
 /*---------------------------------------------------------------------------*/
 int
 ip64_addr_4to6(const uip_ip4addr_t *ipv4addr,
-	       uip_ip6addr_t *ipv6addr)
+               uip_ip6addr_t *ipv6addr)
 {
   /* This function converts an IPv4 addresses into an IPv6
      addresses. It returns 0 if it failed to convert the address and
@@ -75,16 +130,16 @@ ip64_addr_4to6(const uip_ip4addr_t *ipv4addr,
   ipv6addr->u8[14] = ipv4addr->u8[2];
   ipv6addr->u8[15] = ipv4addr->u8[3];
   printf("ip64_addr_4to6: IPv6-encoded IPv4 address %d.%d.%d.%d\n",
-	 ipv4addr->u8[0], ipv4addr->u8[1],
-	 ipv4addr->u8[2], ipv4addr->u8[3]);
+         ipv4addr->u8[0], ipv4addr->u8[1],
+         ipv4addr->u8[2], ipv4addr->u8[3]);
 
   /* Conversion succeeded, we return non-zero. */
   return 1;
 }
 /*---------------------------------------------------------------------------*/
 int
 ip64_addr_6to4(const uip_ip6addr_t *ipv6addr,
-	       uip_ip4addr_t *ipv4addr)
+               uip_ip4addr_t *ipv4addr)
 {
   /* This function converts IPv6 addresses to IPv4 addresses. It
      returns 0 if it failed to convert the address and non-zero if it
@@ -105,17 +160,51 @@ ip64_addr_6to4(const uip_ip6addr_t *ipv6addr,
      ipv6addr->u8[9] == 0 &&
      ipv6addr->u8[10] == 0xff &&
      ipv6addr->u8[11] == 0xff) {
+
     ipv4addr->u8[0] = ipv6addr->u8[12];
     ipv4addr->u8[1] = ipv6addr->u8[13];
     ipv4addr->u8[2] = ipv6addr->u8[14];
     ipv4addr->u8[3] = ipv6addr->u8[15];
 
     printf("ip64_addr_6to4: IPv6-encoded IPv4 address %d.%d.%d.%d\n",
-	   ipv4addr->u8[0], ipv4addr->u8[1],
-	   ipv4addr->u8[2], ipv4addr->u8[3]);
+           ipv4addr->u8[0], ipv4addr->u8[1],
+           ipv4addr->u8[2], ipv4addr->u8[3]);
 
     /* Conversion succeeded, we return non-zero. */
     return 1;
+  } else if(ipv6addr->u8[0] == 00 &&
+            ipv6addr->u8[1] == 0x64 &&
+            ipv6addr->u8[2] == 0xff &&
+            ipv6addr->u8[3] == 0x9b &&
+            ipv6addr->u8[4] == 0 &&
+            ipv6addr->u8[5] == 0 &&
+            ipv6addr->u8[6] == 0 &&
+            ipv6addr->u8[7] == 0 &&
+            ipv6addr->u8[8] == 0 &&
+            ipv6addr->u8[9] == 0 &&
+            ipv6addr->u8[10] == 0 &&
+            ipv6addr->u8[11] == 0) {
+
+    /*
+     * Handle IPv6 addresses using the "Well-Know Prefix" 64:ff9b::/96.
+     * Not allowed for private (RFC1918) IPv4 addresses as per RFC 6052.
+     */
+
+    ipv4addr->u8[0] = ipv6addr->u8[12];
+    ipv4addr->u8[1] = ipv6addr->u8[13];
+    ipv4addr->u8[2] = ipv6addr->u8[14];
+    ipv4addr->u8[3] = ipv6addr->u8[15];
+
+    if(!ip64_addr_ipv4_is_private(ipv4addr)) {
+      printf("ip64_addr_6to4: IPv6-encoded IPv4 address %d.%d.%d.%d\n",
+             ipv4addr->u8[0], ipv4addr->u8[1],
+             ipv4addr->u8[2], ipv4addr->u8[3]);
+      /* Conversion succeeded, we return non-zero. */
+      return 1;
+    } else {
+      /* WKP not allowed for private IPv4 addresses. Drop the packet */
+      printf("ip64_addr_6to4: WKP not allowed for private IPv4 address\n");
+    }
   }
   /* We could not convert the IPv6 address, so we return 0. */
   return 0;