android clat service
This software provides the nat 4->6 translation needed for the "clat" part of
the 464xlat standard. It is needed for better IPv4 application support while
on an IPv6-only mobile network connection using 464xlat's nat64 (such as
T-Mobile's IPv6 trial).
A general diagram of how 464xlat works:
http://dan.drown.org/android/clat/Clat-Plat.png
Depends-on: I2392f8127dcd90d16b0f20ff31bcc5aa096db464
Change-Id: If2bc6916fc66fd4bca7cc241c83cfae839b82e15
Signed-off-by: Daniel Drown <dan-android@drown.org>
diff --git a/netlink_callbacks.c b/netlink_callbacks.c
new file mode 100644
index 0000000..5e0f34e
--- /dev/null
+++ b/netlink_callbacks.c
@@ -0,0 +1,66 @@
+/*
+ * Copyright 2012 Daniel Drown <dan-android@drown.org>
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ * netlink_callbacks.c - generic callbacks for netlink responses
+ */
+#include <netinet/in.h>
+#include <net/if.h>
+
+#include <linux/rtnetlink.h>
+#include <netlink/handlers.h>
+#include <netlink/msg.h>
+
+/* function: ack_handler
+ * generic netlink callback for ack messages
+ * msg - netlink message
+ * data - pointer to an int, stores the success code
+ */
+static int ack_handler(struct nl_msg *msg, void *data) {
+ int *retval = data;
+ *retval = 0;
+ return NL_OK;
+}
+
+/* function: error_handler
+ * generic netlink callback for error messages
+ * nla - error source
+ * err - netlink error message
+ * arg - pointer to an int, stores the error code
+ */
+static int error_handler(struct sockaddr_nl *nla, struct nlmsgerr *err, void *arg) {
+ int *retval = arg;
+ if(err->error < 0) {
+ *retval = err->error;
+ } else {
+ *retval = 0; // NLMSG_ERROR used as reply type on no error
+ }
+ return NL_OK;
+}
+
+/* function: alloc_ack_callbacks
+ * allocates a set of netlink callbacks. returns NULL on failure. callbacks will modify retval with <0 meaning failure
+ * retval - shared state between caller and callback functions
+ */
+struct nl_cb *alloc_ack_callbacks(int *retval) {
+ struct nl_cb *callbacks;
+
+ callbacks = nl_cb_alloc(NL_CB_DEFAULT);
+ if(!callbacks) {
+ return NULL;
+ }
+ nl_cb_set(callbacks, NL_CB_ACK, NL_CB_CUSTOM, ack_handler, retval);
+ nl_cb_err(callbacks, NL_CB_CUSTOM, error_handler, retval);
+ return callbacks;
+}
