gresolv: Calculate precedence/label/etc required for RFC3484 sorting

diff --git a/gweb/gresolv.c b/gweb/gresolv.c
index 2b686a0..a74e54f 100644 (file)
--- a/gweb/gresolv.c
+++ b/gweb/gresolv.c
@@ -39,6 +39,8 @@
 struct sort_result {
        int precedence;
        int scope;
+       int src_label;
+       int dst_label;
        gboolean reachable;
        union {
                struct sockaddr sa;
@@ -109,6 +111,7 @@ struct _GResolv {
 };
 
 static void sort_and_return_results(struct resolv_lookup *lookup);
+static void rfc3484_sort_results(struct resolv_lookup *lookup);
 
 static inline void debug(GResolv *resolv, const char *format, ...)
 {
@@ -554,7 +557,7 @@ static void sort_and_return_results(struct resolv_lookup *lookup)
        if (!results)
                return;
 
-       /* FIXME: Now sort them properly according to RFC3484 and /etc/gai.conf */
+       rfc3484_sort_results(lookup);
 
        for (i = 0; i < lookup->nr_results; i++) {
                if (lookup->results[i].dst.sa.sa_family == AF_INET) {
@@ -687,3 +690,157 @@ gboolean g_resolv_cancel_lookup(GResolv *resolv, guint id)
 
        return TRUE;
 }
+
+static void find_srcaddr(struct sort_result *res)
+{
+       int fd;
+       socklen_t sl = sizeof(res->src);
+
+       fd = socket(res->dst.sa.sa_family, SOCK_DGRAM, IPPROTO_IP);
+       if (fd < 0)
+               return;
+
+       if (connect(fd, &res->dst.sa, sizeof(res->dst))) {
+               close(fd);
+               return;
+       }
+       if (getsockname(fd, &res->src.sa, &sl)) {
+               close(fd);
+               return;
+       }
+       res->reachable = TRUE;
+       close(fd);
+}
+
+struct gai_table
+{
+       unsigned char addr[NS_IN6ADDRSZ];
+       int mask;
+       int value;
+};
+
+static const struct gai_table gai_labels[] = {
+       {
+               .addr = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+                         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01 },
+               .mask = 128,
+               .value = 0,
+       }, {
+               .addr = { 0x20, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+                         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
+               .mask = 16,
+               .value = 2,
+       }, {
+               .addr = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+                         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
+               .mask = 96,
+               .value = 3,
+       }, {
+               .addr = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+                         0x00, 0x00, 0xff, 0xff, 0x00, 0x00, 0x00, 0x00 },
+               .mask = 96,
+               .value = 4,
+       }, {
+               /* Variations from RFC 3484, matching glibc behaviour */
+               .addr = { 0xfe, 0xc0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+                         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
+               .mask = 10,
+               .value = 5,
+       }, {
+               .addr = { 0xfc, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+                         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
+               .mask = 7,
+               .value = 6,
+       }, {
+               .addr = { 0x20, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+                         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
+               .mask = 32,
+               .value = 7,
+       }, {
+               /* catch-all */
+               .addr = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+                         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
+               .mask = 0,
+               .value = 1,
+       }
+};
+
+static const struct gai_table gai_precedences[] = {
+       {
+               .addr = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+                         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01 },
+               .mask = 128,
+               .value = 50,
+       }, {
+               .addr = { 0x20, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+                         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
+               .mask = 16,
+               .value = 30,
+       }, {
+               .addr = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+                         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
+               .mask = 96,
+               .value = 20,
+       }, {
+               .addr = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+                         0x00, 0x00, 0xff, 0xff, 0x00, 0x00, 0x00, 0x00 },
+               .mask = 96,
+               .value = 10,
+       }, {
+               .addr = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+                         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
+               .mask = 0,
+               .value = 40,
+       }
+};
+
+static unsigned char v4mapped[] = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+                                   0x00, 0x00, 0xff, 0xff, 0x00, 0x00, 0x00, 0x00 };
+
+static gboolean mask_compare(const unsigned char *one, const unsigned char *two, int mask)
+{
+       if (mask > 8) {
+               if (memcmp(one, two, mask / 8))
+                       return FALSE;
+               one += mask / 8;
+               two += mask / 8;
+               mask %= 8;
+       }
+       if (mask && ((*one ^ *two) >> (8-mask)))
+           return FALSE;
+
+       return TRUE;
+}
+
+static int match_gai_table(struct sockaddr *sa, const struct gai_table *tbl)
+{
+       struct sockaddr_in *sin = (void *)sa;
+       struct sockaddr_in6 *sin6 = (void *)sa;
+       void *addr;
+
+       if (sa->sa_family == AF_INET) {
+               addr = v4mapped;
+               memcpy(v4mapped+12, &sin->sin_addr, NS_INADDRSZ);
+       } else
+               addr = &sin6->sin6_addr;
+
+       while (1) {
+               if (mask_compare(addr, tbl->addr, tbl->mask))
+                       return tbl->value;
+               tbl++;
+       }
+}
+
+static void rfc3484_sort_results(struct resolv_lookup *lookup)
+{
+       int i;
+
+       for (i = 0; i < lookup->nr_results; i++) {
+               struct sort_result *res = &lookup->results[i];
+               find_srcaddr(res);
+               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);
+       }
+       /* FIXME: Actually *sort* them... */
+}