Make DNS request for plat prefix detection network specific.

When plat prefix detection is done on a non-default network it
must use the network specific version of getaddrinfo() so the
plat prefix corresponds to the particular network.  The network
is specified to clatd via a NetID command line argument.

(cherry picked from commit a1c871c8efad6c0b69e27d3b85e82a27e282b8be)

Change-Id: I270c5afc4b445cf20e95fd3e58eada6bc24b16ef

6 files changed, 37 insertions, 16 deletions

diff --git a/Android.mk b/Android.mk
index 72fc0f9..f94acdf 100644
--- a/Android.mk
+++ b/Android.mk
@@ -4,7 +4,7 @@ include $(CLEAR_VARS)
 LOCAL_SRC_FILES:=clatd.c dump.c checksum.c translate.c icmp.c ipv4.c ipv6.c config.c dns64.c logging.c getaddr.c getroute.c netlink_callbacks.c netlink_msg.c setif.c setroute.c mtu.c
 
 LOCAL_CFLAGS := -Wall -Werror -Wunused-parameter
-LOCAL_C_INCLUDES := external/libnl/include
+LOCAL_C_INCLUDES := external/libnl/include bionic/libc/dns/include
 LOCAL_STATIC_LIBRARIES := libnl
 LOCAL_SHARED_LIBRARIES := libcutils liblog
 
diff --git a/clatd.c b/clatd.c
index 63c4d6d..7b8e43f 100644
--- a/clatd.c
+++ b/clatd.c
@@ -42,6 +42,7 @@
 #include "clatd.h"
 #include "config.h"
 #include "logging.h"
+#include "resolv_netid.h"
 #include "setif.h"
 #include "setroute.h"
 #include "mtu.h"
@@ -252,11 +253,12 @@ void drop_root() {
  * uplink_interface - network interface to use to reach the ipv6 internet
  * plat_prefix      - PLAT prefix to use
  * tunnel           - tun device data
+ * net_id           - NetID to use, NETID_UNSET indicates use of default network
  */
-void configure_interface(const char *uplink_interface, const char *plat_prefix, struct tun_data *tunnel) {
+void configure_interface(const char *uplink_interface, const char *plat_prefix, struct tun_data *tunnel, unsigned net_id) {
   int error;
 
-  if(!read_config("/system/etc/clatd.conf", uplink_interface, plat_prefix)) {
+  if(!read_config("/system/etc/clatd.conf", uplink_interface, plat_prefix, net_id)) {
     logmsg(ANDROID_LOG_FATAL,"read_config failed");
     exit(1);
   }
@@ -374,6 +376,7 @@ void print_help() {
   printf("android-clat arguments:\n");
   printf("-i [uplink interface]\n");
   printf("-p [plat prefix]\n");
+  printf("-n [NetId]\n");
 }
 
 /* function: main
@@ -382,12 +385,13 @@ void print_help() {
 int main(int argc, char **argv) {
   struct tun_data tunnel;
   int opt;
-  char *uplink_interface = NULL, *plat_prefix = NULL;
+  char *uplink_interface = NULL, *plat_prefix = NULL, *net_id_str = NULL;
+  unsigned net_id = NETID_UNSET;
 
   strcpy(tunnel.device6, DEVICENAME6);
   strcpy(tunnel.device4, DEVICENAME4);
 
-  while((opt = getopt(argc, argv, "i:p:h")) != -1) {
+  while((opt = getopt(argc, argv, "i:p:n:h")) != -1) {
     switch(opt) {
       case 'i':
         uplink_interface = optarg;
@@ -395,6 +399,9 @@ int main(int argc, char **argv) {
       case 'p':
         plat_prefix = optarg;
         break;
+      case 'n':
+        net_id_str = optarg;
+        break;
       case 'h':
       default:
         print_help();
@@ -408,6 +415,14 @@ int main(int argc, char **argv) {
     printf("I need an interface\n");
     exit(1);
   }
+  if (net_id_str != NULL) {
+    char *end_ptr;
+    net_id = strtoul(net_id_str, &end_ptr, 0);
+    if (net_id == ULONG_MAX || *net_id_str == 0 || *end_ptr != 0) {
+      logmsg(ANDROID_LOG_FATAL, "clatd called with invalid NetID %s", net_id_str);
+      exit(1);
+    }
+  }
   logmsg(ANDROID_LOG_INFO, "Starting clat version %s on %s", CLATD_VERSION, uplink_interface);
 
   // open the tunnel device before dropping privs
@@ -438,7 +453,7 @@ int main(int argc, char **argv) {
   // "local", but that only works for the netd process itself.
   unsetenv("ANDROID_DNS_MODE");
 
-  configure_interface(uplink_interface, plat_prefix, &tunnel);
+  configure_interface(uplink_interface, plat_prefix, &tunnel, net_id);
 
   set_forwarding(forwarding_fd,"1\n");
 
diff --git a/config.c b/config.c
index b82ac6c..3d39ff0 100644
--- a/config.c
+++ b/config.c
@@ -152,15 +152,16 @@ void free_config() {
 
 /* 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() {
+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,&tmp_ptr);
+    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;
@@ -223,8 +224,10 @@ int subnet_from_interface(cnode *root, const char *interface) {
  * 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) {
+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;
 
@@ -277,7 +280,7 @@ int read_config(const char *file, const char *uplink_interface, const char *plat
 
       if(!(Global_Clatd_Config.plat_from_dns64_hostname = config_item_str(root, "plat_from_dns64_hostname", DEFAULT_DNS64_DETECTION_HOSTNAME)))
         goto failed;
-      dns64_detection();
+      dns64_detection(net_id);
     }
   }
 
diff --git a/config.h b/config.h
index 18760c3..fa47152 100644
--- a/config.h
+++ b/config.h
@@ -39,7 +39,8 @@ struct clat_config {
 
 extern struct clat_config Global_Clatd_Config;
 
-int read_config(const char *file, const char *uplink_interface, const char *plat_prefix);
+int read_config(const char *file, const char *uplink_interface, const char *plat_prefix,
+        unsigned net_id);
 void config_generate_local_ipv6_subnet(struct in6_addr *interface_ip);
 
 #endif /* __CONFIG_H__ */
diff --git a/dns64.c b/dns64.c
index b139fe4..ce8539d 100644
--- a/dns64.c
+++ b/dns64.c
@@ -27,13 +27,15 @@
 
 #include "dns64.h"
 #include "logging.h"
+#include "resolv_netid.h"
 
 /* function: plat_prefix
  * looks up an ipv4-only hostname and looks for a nat64 /96 prefix, returns 1 on success, 0 on temporary failure, -1 on permanent failure
- * ipv4_name - name to lookup
- * prefix    - the plat /96 prefix
+ * ipv4_name  - name to lookup
+ * net_id     - (optional) netId to use, NETID_UNSET indicates use of default network
+ * prefix     - the plat /96 prefix
  */
-int plat_prefix(const char *ipv4_name, struct in6_addr *prefix) {
+int plat_prefix(const char *ipv4_name, unsigned net_id, struct in6_addr *prefix) {
   struct addrinfo hints, *result, *p;
   int status, plat_addr_set, ipv4_records, ipv6_records;
   struct in6_addr plat_addr, this_plat_addr;
@@ -48,7 +50,7 @@ int plat_prefix(const char *ipv4_name, struct in6_addr *prefix) {
 
   bzero(&hints, sizeof(hints));
   hints.ai_family = AF_UNSPEC;
-  status = getaddrinfo(ipv4_name, NULL, &hints, &result);
+  status = android_getaddrinfofornet(ipv4_name, NULL, &hints, net_id, MARK_UNSET, &result);
   if(status != 0) {
     logmsg(ANDROID_LOG_ERROR,"plat_prefix/dns(%s) status = %d/%s\n", ipv4_name, status, gai_strerror(status));
     return 0;
diff --git a/dns64.h b/dns64.h
index f295e50..f5eaea8 100644
--- a/dns64.h
+++ b/dns64.h
@@ -18,6 +18,6 @@
 #ifndef __DNS64_H__
 #define __DNS64_H__
 
-int plat_prefix(const char *ipv4_name, struct in6_addr *prefix);
+int plat_prefix(const char *ipv4_name, unsigned net_id, struct in6_addr *prefix);
 
 #endif