gresolv: Add scope handling to RFC3484 sort

diff --git a/gweb/gresolv.c b/gweb/gresolv.c
index a5fc152..ed1ccab 100644 (file)
--- a/gweb/gresolv.c
+++ b/gweb/gresolv.c
@@ -39,7 +39,8 @@
 
 struct sort_result {
        int precedence;
-       int scope;
+       int src_scope;
+       int dst_scope;
        int src_label;
        int dst_label;
        gboolean reachable;
@@ -832,6 +833,49 @@ static int match_gai_table(struct sockaddr *sa, const struct gai_table *tbl)
        }
 }
 
+#define DQUAD(_a,_b,_c,_d) ( ((_a)<<24) | ((_b)<<16) | ((_c)<<8) | (_d) )
+#define V4MATCH(addr, a,b,c,d, m) ( ((addr) ^ DQUAD(a,b,c,d)) >> (32 - (m)) )
+
+#define RFC3484_SCOPE_LINK     2
+#define RFC3484_SCOPE_SITE     5
+#define RFC3484_SCOPE_GLOBAL   14
+
+static int addr_scope(struct sockaddr *sa)
+{
+       if (sa->sa_family == AF_INET) {
+               struct sockaddr_in *sin = (void *)sa;
+               guint32 addr = ntohl(sin->sin_addr.s_addr);
+
+               if (V4MATCH(addr, 169,254,0,0, 16) ||
+                   V4MATCH(addr, 127,0,0,0,   8))
+                       return RFC3484_SCOPE_LINK;
+
+               /* Site-local */
+               if (V4MATCH(addr, 10,0,0,0,    8) ||
+                   V4MATCH(addr, 172,16,0,0,  12) ||
+                   V4MATCH(addr, 192,168,0,0, 16))
+                       return RFC3484_SCOPE_SITE;
+
+               /* Global */
+               return RFC3484_SCOPE_GLOBAL;
+       } else {
+               struct sockaddr_in6 *sin6 = (void *)sa;
+
+               /* Multicast addresses have a 4-bit scope field */
+               if (IN6_IS_ADDR_MULTICAST(&sin6->sin6_addr))
+                       return sin6->sin6_addr.s6_addr[1] & 0xf;
+
+               if (IN6_IS_ADDR_LINKLOCAL(&sin6->sin6_addr) ||
+                   IN6_IS_ADDR_LOOPBACK(&sin6->sin6_addr))
+                       return RFC3484_SCOPE_LINK;
+
+               if (IN6_IS_ADDR_SITELOCAL(&sin6->sin6_addr))
+                       return RFC3484_SCOPE_SITE;
+
+               return RFC3484_SCOPE_GLOBAL;
+       }
+}
+
 static int rfc3484_compare(const void *__one, const void *__two)
 {
        const struct sort_result *one = __one;
@@ -844,6 +888,12 @@ static int rfc3484_compare(const void *__one, const void *__two)
                return 1;
 
        /* Rule 2: Prefer matching scope */
+       if (one->dst_scope == one->src_scope &&
+           two->dst_scope != two->src_scope)
+               return -1;
+       else if (two->dst_scope == two->src_scope &&
+                one->dst_scope != one->src_scope)
+               return 1;
 
        /* Rule 3: Avoid deprecated addresses */
 
@@ -866,6 +916,8 @@ static int rfc3484_compare(const void *__one, const void *__two)
        /* Rule 7: Prefer native transport */
 
        /* Rule 8: Prefer smaller scope */
+       if (one->dst_scope != two->dst_scope)
+               return one->dst_scope - two->dst_scope;
 
        /* Rule 9: Use longest matching prefix */
 
@@ -886,6 +938,8 @@ static void rfc3484_sort_results(struct resolv_lookup *lookup)
                res->precedence = match_gai_table(&res->dst.sa, gai_precedences);
                res->dst_label = match_gai_table(&res->dst.sa, gai_labels);
                res->src_label = match_gai_table(&res->src.sa, gai_labels);
+               res->dst_scope = addr_scope(&res->dst.sa);
+               res->src_scope = addr_scope(&res->src.sa);
        }
 
        qsort(lookup->results, lookup->nr_results, sizeof(struct sort_result),