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/setif.c b/setif.c
new file mode 100644
index 0000000..5ee00bc
--- /dev/null
+++ b/setif.c
@@ -0,0 +1,129 @@
+/*
+ * 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.
+ *
+ * setif.c - network interface configuration
+ */
+#include <errno.h>
+#include <netinet/in.h>
+#include <net/if.h>
+
+#include <linux/rtnetlink.h>
+#include <netlink/handlers.h>
+#include <netlink/msg.h>
+
+#include "netlink_msg.h"
+
+/* function: add_address
+ * adds an IP address to/from an interface, returns 0 on success and <0 on failure
+ * ifname - name of interface to change
+ * family - address family (AF_INET, AF_INET6)
+ * address - pointer to a struct in_addr or in6_addr
+ * prefixlen - bitlength of network (example: 24 for AF_INET's 255.255.255.0)
+ * broadcast - broadcast address (only for AF_INET, ignored for AF_INET6)
+ */
+int add_address(const char *ifname, int family, const void *address, int prefixlen, const void *broadcast) {
+ int retval;
+ size_t addr_size;
+ struct ifaddrmsg ifa;
+ struct nl_msg *msg = NULL;
+
+ addr_size = inet_family_size(family);
+ if(addr_size == 0) {
+ retval = -EAFNOSUPPORT;
+ goto cleanup;
+ }
+
+ memset(&ifa, 0, sizeof(ifa));
+ if (!(ifa.ifa_index = if_nametoindex(ifname))) {
+ retval = -ENODEV;
+ goto cleanup;
+ }
+ ifa.ifa_family = family;
+ ifa.ifa_prefixlen = prefixlen;
+ ifa.ifa_scope = RT_SCOPE_UNIVERSE;
+
+ msg = nlmsg_alloc_ifaddr(RTM_NEWADDR, NLM_F_ACK | NLM_F_REQUEST | NLM_F_CREATE | NLM_F_REPLACE, &ifa);
+ if(!msg) {
+ retval = -ENOMEM;
+ goto cleanup;
+ }
+
+ if(nla_put(msg, IFA_LOCAL, addr_size, address) < 0) {
+ retval = -ENOMEM;
+ goto cleanup;
+ }
+ if(family == AF_INET6) {
+ // AF_INET6 gets IFA_LOCAL + IFA_ADDRESS
+ if(nla_put(msg, IFA_ADDRESS, addr_size, address) < 0) {
+ retval = -ENOMEM;
+ goto cleanup;
+ }
+ } else if(family == AF_INET) {
+ // AF_INET gets IFA_LOCAL + IFA_BROADCAST
+ if(nla_put(msg, IFA_BROADCAST, addr_size, broadcast) < 0) {
+ retval = -ENOMEM;
+ goto cleanup;
+ }
+ } else {
+ retval = -EAFNOSUPPORT;
+ goto cleanup;
+ }
+
+ retval = netlink_sendrecv(msg);
+
+cleanup:
+ if(msg)
+ nlmsg_free(msg);
+
+ return retval;
+}
+
+/* function: if_up
+ * sets interface link state to up and sets mtu, returns 0 on success and <0 on failure
+ * ifname - interface name to change
+ * mtu - new mtu
+ */
+int if_up(const char *ifname, int mtu) {
+ int retval = -1;
+ struct ifinfomsg ifi;
+ struct nl_msg *msg = NULL;
+
+ memset(&ifi, 0, sizeof(ifi));
+ if (!(ifi.ifi_index = if_nametoindex(ifname))) {
+ retval = -ENODEV;
+ goto cleanup;
+ }
+ ifi.ifi_change = IFF_UP;
+ ifi.ifi_flags = IFF_UP;
+
+ msg = nlmsg_alloc_ifinfo(RTM_SETLINK, NLM_F_ACK | NLM_F_REQUEST | NLM_F_ROOT, &ifi);
+ if(!msg) {
+ retval = -ENOMEM;
+ goto cleanup;
+ }
+
+ if(nla_put(msg, IFLA_MTU, 4, &mtu) < 0) {
+ retval = -ENOMEM;
+ goto cleanup;
+ }
+
+ retval = netlink_sendrecv(msg);
+
+cleanup:
+ if(msg)
+ nlmsg_free(msg);
+
+ return retval;
+}
