1 files changed, 137 insertions, 0 deletions
diff --git a/getaddr.c b/getaddr.c
new file mode 100644
index 0000000..fb761f0
--- /dev/null
+++ b/getaddr.c
@@ -0,0 +1,137 @@
+/*
+ * Copyright 2012 Daniel Drown
+ *
+ * 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.
+ *
+ * getaddr.c - get a locally configured address
+ */
+#include <netinet/in.h>
+#include <strings.h>
+#include <string.h>
+#include <net/if.h>
+
+#include <linux/rtnetlink.h>
+#include <netlink/handlers.h>
+#include <netlink/msg.h>
+
+#include "getaddr.h"
+#include "netlink_msg.h"
+#include "logging.h"
+
+// shared state between getinterface_ip and getaddr_cb
+struct target {
+  int family;
+  unsigned int ifindex;
+  union anyip ip;
+  int foundip;
+};
+
+/* function: getaddr_cb
+ * callback for getinterface_ip
+ * msg  - netlink message
+ * data - (struct target) info for which address we're looking for
+ */
+static int getaddr_cb(struct nl_msg *msg, void *data) {
+  struct ifaddrmsg *ifa_p;
+  struct rtattr *rta_p;
+  int rta_len;
+  struct target *targ_p = (struct target *)data;
+
+  ifa_p = (struct ifaddrmsg *)nlmsg_data(nlmsg_hdr(msg));
+  rta_p = (struct rtattr *)IFA_RTA(ifa_p);
+
+  if(ifa_p->ifa_index != targ_p->ifindex)
+    return NL_OK;
+
+  if(ifa_p->ifa_scope != RT_SCOPE_UNIVERSE)
+    return NL_OK;
+
+  rta_len = RTM_PAYLOAD(nlmsg_hdr(msg));
+  for (; RTA_OK(rta_p, rta_len); rta_p = RTA_NEXT(rta_p, rta_len)) {
+    switch(rta_p->rta_type) {
+      case IFA_ADDRESS:
+        if((targ_p->family == AF_INET6) && !(ifa_p->ifa_flags & IFA_F_SECONDARY)) {
+          memcpy(&targ_p->ip.ip6, RTA_DATA(rta_p), rta_p->rta_len - sizeof(struct rtattr));
+          targ_p->foundip = 1;
+          return NL_OK;
+        }
+        break;
+      case IFA_LOCAL:
+        if(targ_p->family == AF_INET) {
+          memcpy(&targ_p->ip.ip4, RTA_DATA(rta_p), rta_p->rta_len - sizeof(struct rtattr));
+          targ_p->foundip = 1;
+          return NL_OK;
+        }
+        break;
+    }
+  }
+
+  return NL_OK;
+}
+
+/* function: error_handler
+ * error callback for getinterface_ip
+ * nla  - source of the error message
+ * err  - netlink message
+ * arg  - (struct target) info for which address we're looking for
+ */
+static int error_handler(struct sockaddr_nl *nla, struct nlmsgerr *err, void *arg) {
+  return NL_OK;
+}
+
+/* function: getinterface_ip
+ * finds the first global non-privacy IP of the given family for the given interface, or returns NULL.  caller frees pointer
+ * interface - interface to look for
+ * family    - family
+ */
+union anyip *getinterface_ip(const char *interface, int family) {
+  struct ifaddrmsg ifa;
+  struct nl_cb *callbacks = NULL;
+  struct target targ;
+  union anyip *retval = NULL;
+
+  targ.family = family;
+  targ.foundip = 0;
+  targ.ifindex = if_nametoindex(interface);
+  if(targ.ifindex == 0) {
+    return NULL; // interface not found
+  }
+
+  memset(&ifa, 0, sizeof(ifa));
+  ifa.ifa_family = targ.family;
+
+  callbacks = nl_cb_alloc(NL_CB_DEFAULT);
+  if(!callbacks) {
+    goto cleanup;
+  }
+  nl_cb_set(callbacks, NL_CB_VALID, NL_CB_CUSTOM, getaddr_cb, &targ);
+  nl_cb_err(callbacks, NL_CB_CUSTOM, error_handler, &targ);
+
+  // sends message and waits for a response
+  send_ifaddrmsg(RTM_GETADDR, NLM_F_REQUEST | NLM_F_ROOT, &ifa, callbacks);
+
+  if(targ.foundip) {
+    retval = malloc(sizeof(union anyip));
+    if(!retval) {
+      logmsg(ANDROID_LOG_FATAL,"getinterface_ip/out of memory");
+      goto cleanup;
+    }
+    memcpy(retval, &targ.ip, sizeof(union anyip));
+  }
+
+cleanup:
+  if(callbacks)
+    nl_cb_put(callbacks);
+
+  return retval;
+}