Support the subnet attribute in the attr plugin

src/libhydra/plugins/attr/attr_provider.c

@@ -148,6 +148,7 @@ static struct {
 	{"dhcp",		INTERNAL_IP4_DHCP,		INTERNAL_IP6_DHCP},
 	{"netmask",		INTERNAL_IP4_NETMASK,	INTERNAL_IP6_NETMASK},
 	{"server",		INTERNAL_IP4_SERVER,	INTERNAL_IP6_SERVER},
+	{"subnet",		INTERNAL_IP4_SUBNET,	INTERNAL_IP6_SUBNET},
 };
 
 /**
@@ -165,12 +166,19 @@ static void load_entries(private_attr_provider_t *this)
 		configuration_attribute_type_t type;
 		attribute_entry_t *entry;
 		host_t *host;
-		int i;
+		char *pos;
+		int i, mask = -1;
 
 		type = atoi(key);
 		tokens = enumerator_create_token(value, ",", " ");
 		while (tokens->enumerate(tokens, &token))
 		{
+			pos = strchr(token, '/');
+			if (pos)
+			{
+				*(pos++) = '\0';
+				mask = atoi(pos);
+			}
 			host = host_create_from_string(token, 0);
 			if (!host)
 			{
@@ -201,7 +209,27 @@ static void load_entries(private_attr_provider_t *this)
 			}
 			entry = malloc_thing(attribute_entry_t);
 			entry->type = type;
-			entry->value = chunk_clone(host->get_address(host));
+			if (mask == -1)
+			{
+				entry->value = chunk_clone(host->get_address(host));
+			}
+			else
+			{
+				if (host->get_family(host) == AF_INET)
+				{	/* IPv4 attributes contain a subnet mask */
+					u_int32_t netmask;
+
+					mask = 32 - mask;
+					netmask = htonl((0xFFFFFFFF >> mask) << mask);
+					entry->value = chunk_cat("cc", host->get_address(host),
+											 chunk_from_thing(netmask));
+				}
+				else
+				{	/* IPv6 addresses the prefix only */
+					entry->value = chunk_cat("cc", host->get_address(host),
+											 chunk_from_chars(mask));
+				}
+			}
 			host->destroy(host);
 			this->attributes->insert_last(this->attributes, entry);
 		}