Masquerading of ports now works in outward direction [but nothing arrives]

diff --git a/6bed4router.c b/6bed4router.c
index b2fa893..e06eec4 100644 (file)
--- a/6bed4router.c
+++ b/6bed4router.c
@@ -109,12 +109,14 @@ struct {
                } idata;
                struct {
                        struct ip6_hdr v6hdr;
-                       struct icmp6_hdr v6icmphdr;
+                       union {
+                               struct icmp6_hdr v6icmphdr;
 #ifndef BE_SO_LAME_TO_SUPPRESS_SCTP
-                       struct sctphdr v6sctphdr;
+                               struct sctphdr v6sctphdr;
 #endif
-                       struct tcphdr  v6tcphdr ;
-                       struct udphdr  v6udphdr ;
+                               struct tcphdr  v6tcphdr ;
+                               struct udphdr  v6udphdr ;
+                       } adata;
                } ndata;
        } udata;
 } v4data6;
@@ -129,22 +131,22 @@ struct {
 #define v4v6nexthdr    ( v4data6.udata.ndata.v6hdr.ip6_nxt)
 #define v4v6hoplimit   ( v4data6.udata.ndata.v6hdr.ip6_hops)
 
-#define v4icmp6                (&v4data6.udata.ndata.v6icmphdr)
-#define v4v6icmpdata   ( v4data6.udata.ndata.v6icmphdr.icmp6_data8)
-#define v4v6icmptype   ( v4data6.udata.ndata.v6icmphdr.icmp6_type)
-#define v4v6icmpcode   ( v4data6.udata.ndata.v6icmphdr.icmp6_code)
-#define v4v6icmpcksum  ( v4data6.udata.ndata.v6icmphdr.icmp6_cksum)
+#define v4icmp6                (&v4data6.udata.ndata.adata.v6icmphdr)
+#define v4v6icmpdata   ( v4data6.udata.ndata.adata.v6icmphdr.icmp6_data8)
+#define v4v6icmptype   ( v4data6.udata.ndata.adata.v6icmphdr.icmp6_type)
+#define v4v6icmpcode   ( v4data6.udata.ndata.adata.v6icmphdr.icmp6_code)
+#define v4v6icmpcksum  ( v4data6.udata.ndata.adata.v6icmphdr.icmp6_cksum)
 
-#define v4v6sctpsrcport        ( v4data6.udata.ndata.v6sctphdr.source)
-#define v4v6sctpdstport        ( v4data6.udata.ndata.v6sctphdr.dest)
+#define v4v6sctpsrcport        ( v4data6.udata.ndata.adata.v6sctphdr.source)
+#define v4v6sctpdstport        ( v4data6.udata.ndata.adata.v6sctphdr.dest)
 
-#define v4v6tcpsrcport ( v4data6.udata.ndata.v6tcphdr.source)
-#define v4v6tcpdstport ( v4data6.udata.ndata.v6tcphdr.dest)
+#define v4v6tcpsrcport ( v4data6.udata.ndata.adata.v6tcphdr.source)
+#define v4v6tcpdstport ( v4data6.udata.ndata.adata.v6tcphdr.dest)
 
-#define v4v6udpsrcport ( v4data6.udata.ndata.v6udphdr.source)
-#define v4v6udpdstport ( v4data6.udata.ndata.v6udphdr.dest)
+#define v4v6udpsrcport ( v4data6.udata.ndata.adata.v6udphdr.source)
+#define v4v6udpdstport ( v4data6.udata.ndata.adata.v6udphdr.dest)
 
-#define v4ngbsoltarget (&v4data6.udata.ndata.v6icmphdr.icmp6_data8 [4])
+#define v4ngbsoltarget (&v4data6.udata.ndata.adata.v6icmphdr.icmp6_data8 [4])
 
 
 struct {
@@ -422,6 +424,17 @@ static inline bool is_fc64 (struct in6_addr *ip6) {
        return ip6->s6_addr16 [0] == htons (0xfc64);
 }
 
+/* Test if the src and destination share the same /114 and the destination
+ * fills up the rest with zero bits; in other words, test that this is a
+ * package targeted from a 6bed4peer node to its 6bed4router.  This is used
+ * to distinguish special ICMPv6 messages, as well as masquerading targets.
+ */
+static inline bool is_mine (struct in6_addr *src6, struct in6_addr *dst6) {
+       return ((dst6->s6_addr [15] == 0x00)
+               && ((dst6->s6_addr [14] & 0x3f) == 0x00)
+               && (memcmp (dst6->s6_addr, src6->s6_addr, 14) == 0));
+}
+
 
 /*
  * Validate the originator's IPv6 address.  It should match the
@@ -581,6 +594,59 @@ void handle_4to6_nd (ssize_t v4ngbcmdlen) {
 }
 
 
+/*
+ * Forward a message to the masquerading target, or drop it.  This is done
+ * with non-6bed4 packets that are sent from a 6bed4peer node to its
+ * 6bed4router address; see is_mine() for the definition.  The general idea
+ * is that the address that is to be masqueraded can later be reconstructed
+ * from the 6bed4peer's address.
+ */
+void handle_4to6_masquerading (ssize_t v4datalen) {
+       fprintf (stderr, "Traffic to 6bed4router may be fit for masquerading\n");
+       uint16_t *portpairs = NULL;
+       uint16_t numpairs = 0;
+       uint16_t port;
+       switch (v4v6nexthdr) {
+#ifndef BE_SO_LAME_TO_SUPPRESS_SCTP
+       case IPPROTO_SCTP:
+               portpairs = masqportpairs [0];  // 's'
+               numpairs  = num_masqportpairs [0];
+               port = ntohs (v4v6sctpdstport);
+               break;
+#endif
+       case IPPROTO_TCP:
+               portpairs = masqportpairs [1];  // 't'
+               numpairs  = num_masqportpairs [1];
+               port = ntohs (v4v6tcpdstport);
+               break;
+       case IPPROTO_UDP:
+               portpairs = masqportpairs [2];  // 'u'
+               numpairs  = num_masqportpairs [2];
+               port = ntohs (v4v6udpdstport);
+               break;
+       default:
+               break;
+       }
+       fprintf (stderr, "DEBUG: Looking for masquerading of port %d in %d entries\n", port, numpairs);
+       while (numpairs-- > 0) {
+               if ((port >= portpairs [0]) && (port <= portpairs [1])) {
+                       //
+                       // Replace masqueraded address by 6bed4router's
+                       fprintf (stderr, "DEBUG: Passing traffic to masquerading address number %d\n", portpairs [2]);
+                       memcpy (v4dst6, masqhost [portpairs [2]], 16);
+                       //
+                       // Forward immediately, and return from this function
+printf ("Writing Masqueraded IPv6, result = %zd\n",
+                       write (v6sox, &v4data6, sizeof (struct tun_pi) + v4datalen));
+                       return;
+               }
+               portpairs += 3;
+       }
+       //
+       // Silently skip the offered packet
+}
+
+
 /* 
  * Forward a message received over the 6bed4 Network over IPv6.
  * Note that existing checksums will work well, as only the
@@ -588,49 +654,6 @@ void handle_4to6_nd (ssize_t v4ngbcmdlen) {
  * checksum calculations.
  */
 void handle_4to6_plain_unicast (ssize_t v4datalen) {
-       //
-       // Masquerade the 6bed4router when addressing a configured port (range)
-       // but only when the destination address is the client's 6bed4router
-       if ((v4dst6->s6_addr [15] == 0x00)
-                       && (v4dst6->s6_addr [14] & 0x3f == 0x00)
-                       && (memcmp (v4dst6, v4src6, 14) == 0)) {
-               uint16_t *portpairs = NULL;
-               uint16_t numpairs = 0;
-               uint16_t port;
-               switch (v4v6nexthdr) {
-#ifndef BE_SO_LAME_TO_SUPPRESS_SCTP
-               case IPPROTO_SCTP:
-                       portpairs = masqportpairs [0];  // 's'
-                       numpairs  = num_masqportpairs [0];
-                       port = ntohs (v4v6srcport);
-                       break;
-#endif
-               case IPPROTO_TCP:
-                       portpairs = masqportpairs [1];  // 't'
-                       numpairs  = num_masqportpairs [1];
-                       port = v4v6tcpsrcport;
-                       break;
-               case IPPROTO_UDP:
-                       portpairs = masqportpairs [2];  // 'u'
-                       numpairs  = num_masqportpairs [2];
-                       port = v4v6udpsrcport;
-                       break;
-               default:
-                       break;
-               }
-               while (numpairs-- > 0) {
-                       if ((port >= portpairs [0]) && (port <= portpairs [1])) {
-                               //
-                               // Replace masqueraded address by 6bed4router's
-                               memcpy (v4dst6, masqhost [portpairs [2]], 16);
-                               //
-                               // Stop further attempts to masquerade
-                       }
-                       portpairs += 2;
-               }
-       }
-       //
-       // Relay the message to an IPv6 recipient on the native IPv6 side
 printf ("Writing IPv6, result = %zd\n",
        write (v6sox, &v4data6, sizeof (struct tun_pi) + v4datalen));
 }
@@ -698,6 +721,8 @@ void handle_4to6 (void) {
                        return;
                }
                handle_4to6_nd (buflen);
+       } else if (is_mine (v4src6, v4dst6)) {
+               handle_4to6_masquerading (buflen);
        } else if ((v4dst6->s6_addr [0] != 0xff) && !(v4dst6->s6_addr [8] & 0x01)) {
                //
                // Plain Unicast
@@ -979,8 +1004,6 @@ int process_args (int argc, char *argv []) {
                                break;
                        }
                        num_masqhost++;
-                       ok = 0; //TODO:IMPLEMENT//
-                       help = 1;
                        break;
                // case 'f':
                // case 'F':