network: Always use the first address of a network

[people/ms/libloc.git] / src / network.c

diff --git a/src/network.c b/src/network.c
index fe5654e182d48d529cca8ca760d1eec51e8ff694..d34f881e1ac4f616c31fd464680e4790dac04228 100644 (file)
--- a/src/network.c
+++ b/src/network.c
@@ -53,34 +53,61 @@ static int valid_prefix(struct in6_addr* address, unsigned int prefix) {
        return 0;
 }
 
+static struct in6_addr prefix_to_bitmask(unsigned int prefix) {
+       struct in6_addr bitmask;
+
+       for (unsigned int i = 0; i < 16; i++)
+               bitmask.s6_addr[i] = 0;
+
+       for (unsigned int i = prefix, j = 0; i > 0; i -= 8, j++) {
+               if (i >= 8)
+                       bitmask.s6_addr[j] = 0xff;
+               else
+                       bitmask.s6_addr[j] = 0xff << (8 - i);
+       }
+
+       return bitmask;
+}
+
+static struct in6_addr make_start_address(struct in6_addr* address, unsigned int prefix) {
+       struct in6_addr a;
+       struct in6_addr bitmask = prefix_to_bitmask(prefix);
+
+       // Perform bitwise AND
+       for (unsigned int i = 0; i < 4; i++)
+               a.s6_addr32[i] = address->s6_addr32[i] & bitmask.s6_addr32[i];
+
+       return a;
+}
+
 LOC_EXPORT int loc_network_new(struct loc_ctx* ctx, struct loc_network** network,
-               struct in6_addr start_address, unsigned int prefix) {
+               struct in6_addr address, unsigned int prefix) {
        // Address cannot be unspecified
-       if (IN6_IS_ADDR_UNSPECIFIED(&start_address)) {
+       if (IN6_IS_ADDR_UNSPECIFIED(&address)) {
                DEBUG(ctx, "Start address is unspecified\n");
                return -EINVAL;
        }
 
        // Address cannot be loopback
-       if (IN6_IS_ADDR_LOOPBACK(&start_address)) {
+       if (IN6_IS_ADDR_LOOPBACK(&address)) {
                DEBUG(ctx, "Start address is loopback address\n");
                return -EINVAL;
        }
 
        // Address cannot be link-local
-       if (IN6_IS_ADDR_LINKLOCAL(&start_address)) {
+       if (IN6_IS_ADDR_LINKLOCAL(&address)) {
                DEBUG(ctx, "Start address cannot be link-local\n");
                return -EINVAL;
        }
 
        // Address cannot be site-local
-       if (IN6_IS_ADDR_SITELOCAL(&start_address)) {
+       if (IN6_IS_ADDR_SITELOCAL(&address)) {
                DEBUG(ctx, "Start address cannot be site-local\n");
                return -EINVAL;
        }
 
        // Validate the prefix
-       if (valid_prefix(&start_address, prefix) != 0) {
+       if (valid_prefix(&address, prefix) != 0) {
                DEBUG(ctx, "Invalid prefix: %u\n", prefix);
                return -EINVAL;
        }
@@ -92,7 +119,8 @@ LOC_EXPORT int loc_network_new(struct loc_ctx* ctx, struct loc_network** network
        n->ctx = loc_ref(ctx);
        n->refcount = 1;
 
-       n->start_address = start_address;
+       // Store the first address in the network
+       n->start_address = make_start_address(&address, prefix);
        n->prefix = prefix;
 
        DEBUG(n->ctx, "Network allocated at %p\n", n);