diff --git a/ap/app/clatd/config.c b/ap/app/clatd/config.c
new file mode 100755
index 0000000..552e9ab
--- /dev/null
+++ b/ap/app/clatd/config.c
@@ -0,0 +1,402 @@
+/*
+ * Copyright 2011 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.
+ *
+ * config.c - configuration settings
+ */
+
+#include <string.h>
+#include <stdlib.h>
+#include <arpa/inet.h>
+#include <stdio.h>
+#include <limits.h>
+#include <errno.h>
+#include <unistd.h>
+
+//#include <cutils/config_utils.h>
+#include "ifc.h"
+#include "config_utils.h"
+
+#include "config.h"
+#include "dns64.h"
+#include "logging.h"
+#include "getaddr.h"
+#include "clatd.h"
+#include "checksum.h"
+
+void arc4random_buf(void *buf, size_t n);
+
+struct clat_config Global_Clatd_Config;
+
+/* function: config_item_str
+ * locates the config item and returns the pointer to a string, or NULL on failure.  Caller frees pointer
+ * root       - parsed configuration
+ * item_name  - name of config item to locate
+ * defaultvar - value to use if config item isn't present
+ */
+char *config_item_str(cnode *root, const char *item_name, const char *defaultvar) {
+  const char *tmp;
+
+  if(!(tmp = config_str(root, item_name, defaultvar))) {
+    logmsg(ANDROID_LOG_FATAL,"%s config item needed",item_name);
+    return NULL;
+  }
+  return strdup(tmp);
+}
+
+/* function: config_item_int16_t
+ * locates the config item, parses the integer, and returns the pointer ret_val_ptr, or NULL on failure
+ * root        - parsed configuration
+ * item_name   - name of config item to locate
+ * defaultvar  - value to use if config item isn't present
+ * ret_val_ptr - pointer for return value storage
+ */
+int16_t *config_item_int16_t(cnode *root, const char *item_name, const char *defaultvar, int16_t *ret_val_ptr) {
+  const char *tmp;
+  char *endptr;
+  long int conf_int;
+
+  if(!(tmp = config_str(root, item_name, defaultvar))) {
+    logmsg(ANDROID_LOG_FATAL,"%s config item needed",item_name);
+    return NULL;
+  }
+
+  errno = 0;
+  conf_int = strtol(tmp,&endptr,10);
+  if(errno > 0) {
+    logmsg(ANDROID_LOG_FATAL,"%s config item is not numeric: %s (error=%s)",item_name,tmp,strerror(errno));
+    return NULL;
+  }
+  if(endptr == tmp || *tmp == '\0') {
+    logmsg(ANDROID_LOG_FATAL,"%s config item is not numeric: %s",item_name,tmp);
+    return NULL;
+  }
+  if(*endptr != '\0') {
+    logmsg(ANDROID_LOG_FATAL,"%s config item contains non-numeric characters: %s",item_name,endptr);
+    return NULL;
+  }
+  if(conf_int > INT16_MAX || conf_int < INT16_MIN) {
+    logmsg(ANDROID_LOG_FATAL,"%s config item is too big/small: %d",item_name,conf_int);
+    return NULL;
+  }
+  *ret_val_ptr = conf_int;
+  return ret_val_ptr;
+}
+
+/* function: config_item_ip
+ * locates the config item, parses the ipv4 address, and returns the pointer ret_val_ptr, or NULL on failure
+ * root        - parsed configuration
+ * item_name   - name of config item to locate
+ * defaultvar  - value to use if config item isn't present
+ * ret_val_ptr - pointer for return value storage
+ */
+struct in_addr *config_item_ip(cnode *root, const char *item_name, const char *defaultvar, struct in_addr *ret_val_ptr) {
+  const char *tmp;
+  int status;
+
+  if(!(tmp = config_str(root, item_name, defaultvar))) {
+    logmsg(ANDROID_LOG_FATAL,"%s config item needed",item_name);
+    return NULL;
+  }
+
+  status = inet_pton(AF_INET, tmp, ret_val_ptr);
+  if(status <= 0) {
+    logmsg(ANDROID_LOG_FATAL,"invalid IPv4 address specified for %s: %s", item_name, tmp);
+    return NULL;
+  }
+
+  return ret_val_ptr;
+}
+
+/* function: config_item_ip6
+ * locates the config item, parses the ipv6 address, and returns the pointer ret_val_ptr, or NULL on failure
+ * root        - parsed configuration
+ * item_name   - name of config item to locate
+ * defaultvar  - value to use if config item isn't present
+ * ret_val_ptr - pointer for return value storage
+ */
+struct in6_addr *config_item_ip6(cnode *root, const char *item_name, const char *defaultvar, struct in6_addr *ret_val_ptr) {
+  const char *tmp;
+  int status;
+
+  if(!(tmp = config_str(root, item_name, defaultvar))) {
+    logmsg(ANDROID_LOG_FATAL,"%s config item needed",item_name);
+    return NULL;
+  }
+
+  status = inet_pton(AF_INET6, tmp, ret_val_ptr);
+  if(status <= 0) {
+    logmsg(ANDROID_LOG_FATAL,"invalid IPv6 address specified for %s: %s", item_name, tmp);
+    return NULL;
+  }
+
+  return ret_val_ptr;
+}
+
+/* function: free_config
+ * frees the memory used by the global config variable
+ */
+void free_config() {
+  if(Global_Clatd_Config.plat_from_dns64_hostname) {
+    free(Global_Clatd_Config.plat_from_dns64_hostname);
+    Global_Clatd_Config.plat_from_dns64_hostname = NULL;
+  }
+}
+
+/* function: ipv6_prefix_equal
+ * compares the prefixes two ipv6 addresses. assumes the prefix lengths are both /64.
+ * a1 - first address
+ * a2 - second address
+ * returns: 0 if the subnets are different, 1 if they are the same.
+ */
+int ipv6_prefix_equal(struct in6_addr *a1, struct in6_addr *a2) {
+    return !memcmp(a1, a2, 8);
+}
+
+/* function: dns64_detection
+ * does dns lookups to set the plat subnet or exits on failure, waits forever for a dns response with a query backoff timer
+ * net_id - (optional) netId to use, NETID_UNSET indicates use of default network
+ */
+void dns64_detection(unsigned net_id) {
+  int backoff_sleep, status;
+  struct in6_addr tmp_ptr;
+
+  backoff_sleep = 1;
+
+  while(1) {
+    status = plat_prefix(Global_Clatd_Config.plat_from_dns64_hostname,net_id,&tmp_ptr);
+    if(status > 0) {
+      memcpy(&Global_Clatd_Config.plat_subnet, &tmp_ptr, sizeof(struct in6_addr));
+      return;
+    }
+    logmsg(ANDROID_LOG_WARN, "dns64_detection -- error, sleeping for %d seconds", backoff_sleep);
+    sleep(backoff_sleep);
+    backoff_sleep *= 2;
+    if(backoff_sleep >= 1800) {
+      // Scale down to one DNS query per half hour. Unnecessary DNS queries waste power, and the
+      // benefit is minimal (basically, only limited to the case where a network goes from IPv6-only
+      // to IPv6 with NAT64).
+      backoff_sleep = 1800;
+    }
+  }
+}
+
+/* function: gen_random_iid
+ * picks a random interface ID that is checksum neutral with the IPv4 address and the NAT64 prefix
+ * myaddr            - IPv6 address to write to
+ * ipv4_local_subnet - clat IPv4 address
+ * plat_subnet       - NAT64 prefix
+ */
+void gen_random_iid(struct in6_addr *myaddr, struct in_addr *ipv4_local_subnet,
+                    struct in6_addr *plat_subnet) {
+  // Fill last 8 bytes of IPv6 address with random bits.
+  arc4random_buf(&myaddr->s6_addr[8], 8);
+  //arc4random_addrandom(&myaddr->s6_addr[8], 8);
+
+  // Make the IID checksum-neutral. That is, make it so that:
+  //   checksum(Local IPv4 | Remote IPv4) = checksum(Local IPv6 | Remote IPv6)
+  // in other words (because remote IPv6 = NAT64 prefix | Remote IPv4):
+  //   checksum(Local IPv4) = checksum(Local IPv6 | NAT64 prefix)
+  // Do this by adjusting the two bytes in the middle of the IID.
+
+  uint16_t middlebytes = (myaddr->s6_addr[11] << 8) + myaddr->s6_addr[12];
+
+  uint32_t c1 = ip_checksum_add(0, ipv4_local_subnet, sizeof(*ipv4_local_subnet));
+  uint32_t c2 = ip_checksum_add(0, plat_subnet, sizeof(*plat_subnet)) +
+                ip_checksum_add(0, myaddr, sizeof(*myaddr));
+
+  uint16_t delta = ip_checksum_adjust(middlebytes, c1, c2);
+  myaddr->s6_addr[11] = delta >> 8;
+  myaddr->s6_addr[12] = delta & 0xff;
+}
+
+// Factored out to a separate function for testability.
+int connect_is_ipv4_address_free(in_addr_t addr) {
+  int s = socket(AF_INET, SOCK_DGRAM, 0);
+  if (s == -1) {
+    return 0;
+  }
+
+  // Attempt to connect to the address. If the connection succeeds and getsockname returns the same
+  // the address then the address is already assigned to the system and we can't use it.
+  struct sockaddr_in sin = { .sin_family = AF_INET, .sin_addr = { addr }, .sin_port = 53 };
+  socklen_t len = sizeof(sin);
+  int inuse = connect(s, (struct sockaddr *) &sin, sizeof(sin)) == 0 &&
+              getsockname(s, (struct sockaddr *) &sin, &len) == 0 &&
+              (size_t) len >= sizeof(sin) &&
+              sin.sin_addr.s_addr == addr;
+
+  close(s);
+  return !inuse;
+}
+
+addr_free_func config_is_ipv4_address_free = connect_is_ipv4_address_free;
+
+/* function: config_select_ipv4_address
+ * picks a free IPv4 address, starting from ip and trying all addresses in the prefix in order
+ * ip        - the IP address from the configuration file
+ * prefixlen - the length of the prefix from which addresses may be selected.
+ * returns: the IPv4 address, or INADDR_NONE if no addresses were available
+ */
+in_addr_t config_select_ipv4_address(const struct in_addr *ip, int16_t prefixlen) {
+  in_addr_t chosen = INADDR_NONE;
+
+  // Don't accept prefixes that are too large because we scan addresses one by one.
+  if (prefixlen < 16 || prefixlen > 32) {
+      return chosen;
+  }
+
+  // All these are in host byte order.
+  in_addr_t mask = 0xffffffff >> (32 - prefixlen) << (32 - prefixlen);
+  in_addr_t ipv4 = ntohl(ip->s_addr);
+  in_addr_t first_ipv4 = ipv4;
+  in_addr_t prefix = ipv4 & mask;
+
+  // Pick the first IPv4 address in the pool, wrapping around if necessary.
+  // So, for example, 192.0.0.4 -> 192.0.0.5 -> 192.0.0.6 -> 192.0.0.7 -> 192.0.0.0.
+  do {
+     if (config_is_ipv4_address_free(htonl(ipv4))) {
+       chosen = htonl(ipv4);
+       break;
+     }
+     ipv4 = prefix | ((ipv4 + 1) & ~mask);
+  } while (ipv4 != first_ipv4);
+
+  return chosen;
+}
+
+/* function: config_generate_local_ipv6_subnet
+ * generates the local ipv6 subnet when given the interface ip
+ * requires config.ipv6_host_id
+ * interface_ip - in: interface ip, out: local ipv6 host address
+ */
+void config_generate_local_ipv6_subnet(struct in6_addr *interface_ip) {
+  int i;
+
+  if (Global_Clatd_Config.use_dynamic_iid) {
+    /* Generate a random interface ID. */
+    gen_random_iid(interface_ip,
+                   &Global_Clatd_Config.ipv4_local_subnet,
+                   &Global_Clatd_Config.plat_subnet);
+  } else {
+    /* Use the specified interface ID. */
+    for(i = 2; i < 4; i++) {
+      interface_ip->s6_addr32[i] = Global_Clatd_Config.ipv6_host_id.s6_addr32[i];
+    }
+  }
+}
+
+/* function: read_config
+ * reads the config file and parses it into the global variable Global_Clatd_Config. returns 0 on failure, 1 on success
+ * file             - filename to parse
+ * uplink_interface - interface to use to reach the internet and supplier of address space
+ * plat_prefix      - (optional) plat prefix to use, otherwise follow config file
+ * net_id           - (optional) netId to use, NETID_UNSET indicates use of default network
+ */
+int read_config(const char *file, const char *uplink_interface, const char *plat_prefix,
+        unsigned net_id) {
+  cnode *root = config_node("", "");
+  void *tmp_ptr = NULL;
+  unsigned flags;
+
+  if(!root) {
+    logmsg(ANDROID_LOG_FATAL,"out of memory");
+    return 0;
+  }
+
+  memset(&Global_Clatd_Config, '\0', sizeof(Global_Clatd_Config));
+
+  config_load_file(root, file);
+  if(root->first_child == NULL) {
+    logmsg(ANDROID_LOG_FATAL,"Could not read config file %s", file);
+    goto failed;
+  }
+
+  Global_Clatd_Config.default_pdp_interface = strdup(uplink_interface);
+  if (!Global_Clatd_Config.default_pdp_interface)
+    goto failed;
+
+  if(!config_item_int16_t(root, "mtu", "-1", &Global_Clatd_Config.mtu))
+    goto failed;
+
+  if(!config_item_int16_t(root, "ipv4mtu", "-1", &Global_Clatd_Config.ipv4mtu))
+    goto failed;
+
+  if(!config_item_ip(root, "ipv4_local_subnet", DEFAULT_IPV4_LOCAL_SUBNET,
+                     &Global_Clatd_Config.ipv4_local_subnet))
+    goto failed;
+
+  if(!config_item_int16_t(root, "ipv4_local_prefixlen", DEFAULT_IPV4_LOCAL_PREFIXLEN,
+                          &Global_Clatd_Config.ipv4_local_prefixlen))
+    goto failed;
+
+  if(plat_prefix) { // plat subnet is coming from the command line
+    if(inet_pton(AF_INET6, plat_prefix, &Global_Clatd_Config.plat_subnet) <= 0) {
+      logmsg(ANDROID_LOG_FATAL,"invalid IPv6 address specified for plat prefix: %s", plat_prefix);
+      goto failed;
+    }
+  } else {
+    tmp_ptr = (void *)config_item_str(root, "plat_from_dns64", "yes");
+    if(!tmp_ptr || strcmp(tmp_ptr, "no") == 0) {
+      free(tmp_ptr);
+
+      if(!config_item_ip6(root, "plat_subnet", NULL, &Global_Clatd_Config.plat_subnet)) {
+        logmsg(ANDROID_LOG_FATAL, "plat_from_dns64 disabled, but no plat_subnet specified");
+        goto failed;
+      }
+    } else {
+      free(tmp_ptr);
+
+      if(!(Global_Clatd_Config.plat_from_dns64_hostname = config_item_str(root, "plat_from_dns64_hostname", DEFAULT_DNS64_DETECTION_HOSTNAME)))
+        goto failed;
+      dns64_detection(net_id);
+    }
+  }
+
+  if (!config_item_ip6(root, "ipv6_host_id", "::", &Global_Clatd_Config.ipv6_host_id))
+    goto failed;
+
+  /* In order to prevent multiple devices attempting to use the same clat address, never use a
+     statically-configured interface ID on a broadcast interface such as wifi. */
+  if (!IN6_IS_ADDR_UNSPECIFIED(&Global_Clatd_Config.ipv6_host_id)) {
+    ifc_init();
+    ifc_get_info(Global_Clatd_Config.default_pdp_interface, NULL, NULL, &flags);
+    ifc_close();
+    Global_Clatd_Config.use_dynamic_iid = (flags & IFF_BROADCAST) != 0;
+  } else {
+    Global_Clatd_Config.use_dynamic_iid = 1;
+  }
+
+  return 1;
+
+failed:
+  free(root);
+  free_config();
+  return 0;
+}
+
+/* function; dump_config
+ * prints the current config
+ */
+void dump_config() {
+  char charbuffer[INET6_ADDRSTRLEN];
+
+  logmsg(ANDROID_LOG_DEBUG,"mtu = %d",Global_Clatd_Config.mtu);
+  logmsg(ANDROID_LOG_DEBUG,"ipv4mtu = %d",Global_Clatd_Config.ipv4mtu);
+  logmsg(ANDROID_LOG_DEBUG,"ipv6_local_subnet = %s",inet_ntop(AF_INET6, &Global_Clatd_Config.ipv6_local_subnet, charbuffer, sizeof(charbuffer)));
+  logmsg(ANDROID_LOG_DEBUG,"ipv4_local_subnet = %s",inet_ntop(AF_INET, &Global_Clatd_Config.ipv4_local_subnet, charbuffer, sizeof(charbuffer)));
+  logmsg(ANDROID_LOG_DEBUG,"ipv4_local_prefixlen = %d", Global_Clatd_Config.ipv4_local_prefixlen);
+  logmsg(ANDROID_LOG_DEBUG,"plat_subnet = %s",inet_ntop(AF_INET6, &Global_Clatd_Config.plat_subnet, charbuffer, sizeof(charbuffer)));
+  logmsg(ANDROID_LOG_DEBUG,"default_pdp_interface = %s",Global_Clatd_Config.default_pdp_interface);
+}