nl80211: work around libnl bug

libnl has a bug, when binding more than two sockets and releasing one,
it will release the wrong address and then try to reuse it, which fails.
Therefore, we need to reimplement the socket address assignment logic
locally for libnl 1.1.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>

src/drivers/driver_nl80211.c

@@ -40,8 +40,48 @@
 #ifdef CONFIG_LIBNL20
 /* libnl 2.0 compatibility code */
 #define nl_handle nl_sock
-#define nl_handle_alloc_cb nl_socket_alloc_cb
-#define nl_handle_destroy nl_socket_free
+#define nl80211_handle_alloc nl_socket_alloc_cb
+#define nl80211_handle_destroy nl_socket_free
+#else
+/*
+ * libnl 1.1 has a bug, it tries to allocate socket numbers densely
+ * but when you free a socket again it will mess up its bitmap and
+ * and use the wrong number the next time it needs a socket ID.
+ * Therefore, we wrap the handle alloc/destroy and add our own pid
+ * accounting.
+ */
+static uint32_t port_bitmap[32] = { 0 };
+
+static struct nl_handle *nl80211_handle_alloc(void *cb)
+{
+	struct nl_handle *handle;
+	uint32_t pid = getpid() & 0x3FFFFF;
+	int i;
+
+	handle = nl_handle_alloc_cb(cb);
+
+	for (i = 0; i < 1024; i++) {
+		if (port_bitmap[i / 32] & (1 << (i % 32)))
+			continue;
+		port_bitmap[i / 32] |= 1 << (i % 32);
+		pid += i << 22;
+		break;
+	}
+
+	nl_socket_set_local_port(handle, pid);
+
+	return handle;
+}
+
+static void nl80211_handle_destroy(struct nl_handle *handle)
+{
+	uint32_t port = nl_socket_get_local_port(handle);
+
+	port >>= 22;
+	port_bitmap[port / 32] &= ~(1 << (port % 32));
+
+	nl_handle_destroy(handle);
+}
 #endif /* CONFIG_LIBNL20 */
 
 
@@ -1344,14 +1384,14 @@ static int wpa_driver_nl80211_init_nl(struct wpa_driver_nl80211_data *drv)
 		goto err1;
 	}
 
-	drv->nl_handle = nl_handle_alloc_cb(drv->nl_cb);
+	drv->nl_handle = nl80211_handle_alloc(drv->nl_cb);
 	if (drv->nl_handle == NULL) {
 		wpa_printf(MSG_ERROR, "nl80211: Failed to allocate netlink "
 			   "callbacks");
 		goto err2;
 	}
 
-	drv->nl_handle_event = nl_handle_alloc_cb(drv->nl_cb);
+	drv->nl_handle_event = nl80211_handle_alloc(drv->nl_cb);
 	if (drv->nl_handle_event == NULL) {
 		wpa_printf(MSG_ERROR, "nl80211: Failed to allocate netlink "
 			   "callbacks (event)");
@@ -1434,9 +1474,9 @@ err4:
 err3b:
 	nl_cache_free(drv->nl_cache);
 err3:
-	nl_handle_destroy(drv->nl_handle_event);
+	nl80211_handle_destroy(drv->nl_handle_event);
 err2b:
-	nl_handle_destroy(drv->nl_handle);
+	nl80211_handle_destroy(drv->nl_handle);
 err2:
 	nl_cb_put(drv->nl_cb);
 err1:
@@ -1541,7 +1581,7 @@ failed:
 
 	genl_family_put(drv->nl80211);
 	nl_cache_free(drv->nl_cache);
-	nl_handle_destroy(drv->nl_handle);
+	nl80211_handle_destroy(drv->nl_handle);
 	nl_cb_put(drv->nl_cb);
 	eloop_unregister_read_sock(nl_socket_get_fd(drv->nl_handle_event));
 
@@ -1767,8 +1807,8 @@ static void wpa_driver_nl80211_deinit(void *priv)
 	genl_family_put(drv->nl80211);
 	nl_cache_free(drv->nl_cache);
 	nl_cache_free(drv->nl_cache_event);
-	nl_handle_destroy(drv->nl_handle);
-	nl_handle_destroy(drv->nl_handle_event);
+	nl80211_handle_destroy(drv->nl_handle);
+	nl80211_handle_destroy(drv->nl_handle_event);
 	nl_cb_put(drv->nl_cb);
 
 	eloop_cancel_timeout(wpa_driver_nl80211_probe_req_report_timeout,
@@ -5007,7 +5047,7 @@ failed:
 
 	genl_family_put(drv->nl80211);
 	nl_cache_free(drv->nl_cache);
-	nl_handle_destroy(drv->nl_handle);
+	nl80211_handle_destroy(drv->nl_handle);
 	nl_cb_put(drv->nl_cb);
 
 	os_free(drv);