Trie: Clarify handling of less-common net types

For convenience, Trie functions generally accept as input values not only
NET_IPx types of nets, but also NET_VPNx and NET_ROAx types. But returned
values are always NET_IPx types.

filter/trie.c

@@ -373,9 +373,23 @@ trie_add_prefix(struct f_trie *t, const net_addr *net, uint l, uint h)
 
   switch (net->type)
   {
-  case NET_IP4: px = ipt_from_ip4(net4_prefix(net)); v4 = 1; break;
+  case NET_IP4:
-  case NET_IP6: px = ipa_from_ip6(net6_prefix(net)); v4 = 0; break;
+  case NET_VPN4:
-  default: bug("invalid type");
+  case NET_ROA4:
+    px = ipt_from_ip4(net4_prefix(net));
+    v4 = 1;
+    break;
+
+  case NET_IP6:
+  case NET_VPN6:
+  case NET_ROA6:
+  case NET_IP6_SADR:
+    px = ipa_from_ip6(net6_prefix(net));
+    v4 = 0;
+    break;
+
+  default:
+    bug("invalid type");
   }
 
   if (t->ipv4 != v4)
@@ -562,7 +576,9 @@ trie_match_net(const struct f_trie *t, const net_addr *n)
  * can be used to enumerate all matching prefixes for the network @net using
  * function trie_match_next_longest_ip4() or macro TRIE_WALK_TO_ROOT_IP4().
  *
- * This function assumes IPv4 trie, there is also an IPv6 variant.
+ * This function assumes IPv4 trie, there is also an IPv6 variant. The @net
+ * argument is typed as net_addr_ip4, but would accept any IPv4-based net_addr,
+ * like net4_prefix(). Anyway, returned @dst is always net_addr_ip4.
  *
  * Result: 1 if a matching prefix was found, 0 if not.
  */
@@ -571,6 +587,9 @@ trie_match_longest_ip4(const struct f_trie *t, const net_addr_ip4 *net, net_addr
 {
   ASSERT(t->ipv4);
 
+  const ip4_addr prefix = net->prefix;
+  const int pxlen = net->pxlen;
+
   const struct f_trie_node4 *n = &t->root.v4;
   int len = 0;
 
@@ -580,13 +599,13 @@ trie_match_longest_ip4(const struct f_trie *t, const net_addr_ip4 *net, net_addr
   while (n)
   {
     /* We are out of path */
-    if (!ip4_prefix_equal(net->prefix, n->addr, MIN(net->pxlen, n->plen)))
+    if (!ip4_prefix_equal(prefix, n->addr, MIN(pxlen, n->plen)))
       goto done;
 
     /* Check accept mask */
     for (; len < n->plen; len++)
     {
-      if (len > net->pxlen)
+      if (len > pxlen)
 	goto done;
 
       if (ip4_getbit(n->accept, len - 1))
@@ -607,9 +626,9 @@ trie_match_longest_ip4(const struct f_trie *t, const net_addr_ip4 *net, net_addr
     }
 
     /* Check local mask */
-    for (int pos = 1; pos < (1 << TRIE_STEP); pos = 2 * pos + ip4_getbit(net->prefix, len), len++)
+    for (int pos = 1; pos < (1 << TRIE_STEP); pos = 2 * pos + ip4_getbit(prefix, len), len++)
     {
-      if (len > net->pxlen)
+      if (len > pxlen)
 	goto done;
 
       if (n->local & (1u << pos))
@@ -621,16 +640,14 @@ trie_match_longest_ip4(const struct f_trie *t, const net_addr_ip4 *net, net_addr
     }
 
     /* Choose child */
-    n = n->c[ip4_getbits(net->prefix, n->plen, TRIE_STEP)];
+    n = n->c[ip4_getbits(prefix, n->plen, TRIE_STEP)];
   }
 
 done:
   if (last < 0)
     return 0;
 
-  net_copy_ip4(dst, net);
+  *dst = NET_ADDR_IP4(ip4_and(prefix, ip4_mkmask(last)), last);
-  dst->prefix = ip4_and(dst->prefix, ip4_mkmask(last));
-  dst->pxlen = last;
 
   if (found0)
     *found0 = found;
@@ -653,7 +670,9 @@ done:
  * can be used to enumerate all matching prefixes for the network @net using
  * function trie_match_next_longest_ip6() or macro TRIE_WALK_TO_ROOT_IP6().
  *
- * This function assumes IPv6 trie, there is also an IPv4 variant.
+ * This function assumes IPv6 trie, there is also an IPv4 variant. The @net
+ * argument is typed as net_addr_ip6, but would accept any IPv6-based net_addr,
+ * like net6_prefix(). Anyway, returned @dst is always net_addr_ip6.
  *
  * Result: 1 if a matching prefix was found, 0 if not.
  */
@@ -662,6 +681,9 @@ trie_match_longest_ip6(const struct f_trie *t, const net_addr_ip6 *net, net_addr
 {
   ASSERT(!t->ipv4);
 
+  const ip6_addr prefix = net->prefix;
+  const int pxlen = net->pxlen;
+
   const struct f_trie_node6 *n = &t->root.v6;
   int len = 0;
 
@@ -671,13 +693,13 @@ trie_match_longest_ip6(const struct f_trie *t, const net_addr_ip6 *net, net_addr
   while (n)
   {
     /* We are out of path */
-    if (!ip6_prefix_equal(net->prefix, n->addr, MIN(net->pxlen, n->plen)))
+    if (!ip6_prefix_equal(prefix, n->addr, MIN(pxlen, n->plen)))
       goto done;
 
     /* Check accept mask */
     for (; len < n->plen; len++)
     {
-      if (len > net->pxlen)
+      if (len > pxlen)
 	goto done;
 
       if (ip6_getbit(n->accept, len - 1))
@@ -698,9 +720,9 @@ trie_match_longest_ip6(const struct f_trie *t, const net_addr_ip6 *net, net_addr
     }
 
     /* Check local mask */
-    for (int pos = 1; pos < (1 << TRIE_STEP); pos = 2 * pos + ip6_getbit(net->prefix, len), len++)
+    for (int pos = 1; pos < (1 << TRIE_STEP); pos = 2 * pos + ip6_getbit(prefix, len), len++)
     {
-      if (len > net->pxlen)
+      if (len > pxlen)
 	goto done;
 
       if (n->local & (1u << pos))
@@ -712,16 +734,14 @@ trie_match_longest_ip6(const struct f_trie *t, const net_addr_ip6 *net, net_addr
     }
 
     /* Choose child */
-    n = n->c[ip6_getbits(net->prefix, n->plen, TRIE_STEP)];
+    n = n->c[ip6_getbits(prefix, n->plen, TRIE_STEP)];
   }
 
 done:
   if (last < 0)
     return 0;
 
-  net_copy_ip6(dst, net);
+  *dst = NET_ADDR_IP6(ip6_and(prefix, ip6_mkmask(last)), last);
-  dst->prefix = ip6_and(dst->prefix, ip6_mkmask(last));
-  dst->pxlen = last;
 
   if (found0)
     *found0 = found;