NAT: VPP-1531 api cleanup & update

Change-Id: I2492400a67b39a3adbc24ab7cf1ba17a409e95a8
Signed-off-by: Filip Varga <fivarga@cisco.com>

4 files changed, 580 insertions, 422 deletions

diff --git a/src/plugins/nat/nat.api b/src/plugins/nat/nat.api
index 7f9fe3f8e7b..80a70a7e995 100644
--- a/src/plugins/nat/nat.api
+++ b/src/plugins/nat/nat.api
@@ -13,8 +13,9 @@
  * limitations under the License.
  */
 
-option version = "4.1.0";
+option version = "5.0.0";
 import "vnet/ip/ip_types.api";
+import "vnet/interface_types.api";
 
 /**
  * @file nat.api
@@ -28,6 +29,18 @@ import "vnet/ip/ip_types.api";
  * Common NAT plugin APIs
  */
 
+enum nat_config_flags : u8
+{
+  NAT_IS_TWICE_NAT = 0x01,
+  NAT_IS_SELF_TWICE_NAT = 0x02,
+  NAT_IS_OUT2IN_ONLY = 0x04,
+  NAT_IS_ADDR_ONLY = 0x08,
+  NAT_IS_OUTSIDE = 0x10,
+  NAT_IS_INSIDE = 0x20,
+  NAT_IS_STATIC = 0x40,
+  NAT_IS_EXT_HOST_VALID = 0x80,
+};
+
 /** \brief Control ping from client to api server request
     @param client_index - opaque cookie to identify the sender
     @param context - sender context, to match reply w/ request
@@ -65,11 +78,12 @@ define nat_show_config
 /** \brief Show NAT plugin startup config reply
     @param context - sender context, to match reply w/ request
     @param retval - return code for the request
-    @param static_mapping_only - if 1 dynamic translations disabled
-    @param static_mapping_connection_tracking - if 1 create session data
-    @param deterministic - if 1 deterministic mapping
-    @param endpoint_dependent - if 1 endpoint-dependent mode
-    @param out2in_dpo - if 1 out2in dpo mode
+    @param static_mapping_only - if true dynamic translations disabled
+    @param static_mapping_connection_tracking - if true create session data
+    @param deterministic - if true deterministic mapping
+    @param endpoint_dependent - if true endpoint-dependent mode
+    @param out2in_dpo - if true out2in dpo mode
+    @param dslite_ce - if true DS-Lite is CE/B4 element, if false AFTR elemet
     @param translation_buckets - number of translation hash buckets
     @param translation_memory_size - translation hash memory size
     @param user_buckets - number of user hash buckets
@@ -77,7 +91,6 @@ define nat_show_config
     @param max_translations_per_user - maximum number of translations per user
     @param outside_vrf_id - outside VRF id
     @param inside_vrf_id - default inside VRF id
-    @param dslite_ce - if DS-Lite is CE/B4 element, if 0 AFTR elemet
     @param nat64_bib_buckets - number of NAT64 BIB hash buckets
     @param nat64_bib_memory_size - memory size of NAT64 BIB hash
     @param nat64_st_buckets - number of NAT64 session table hash buckets
@@ -87,11 +100,12 @@ define nat_show_config_reply
 {
   u32 context;
   i32 retval;
-  u8 static_mapping_only;
-  u8 static_mapping_connection_tracking;
-  u8 deterministic;
-  u8 endpoint_dependent;
-  u8 out2in_dpo;
+  bool static_mapping_only;
+  bool static_mapping_connection_tracking;
+  bool deterministic;
+  bool endpoint_dependent;
+  bool out2in_dpo;
+  bool dslite_ce;
   u32 translation_buckets;
   u32 translation_memory_size;
   u32 user_buckets;
@@ -99,7 +113,6 @@ define nat_show_config_reply
   u32 max_translations_per_user;
   u32 outside_vrf_id;
   u32 inside_vrf_id;
-  u8 dslite_ce;
   u32 nat64_bib_buckets;
   u32 nat64_bib_memory_size;
   u32 nat64_st_buckets;
@@ -136,7 +149,7 @@ define nat_worker_details {
   u32 context;
   u32 worker_index;
   u32 lcore_id;
-  u8 name[64];
+  string name;
 };
 
 /** \brief Enable/disable NAT IPFIX logging
@@ -144,14 +157,14 @@ define nat_worker_details {
     @param context - sender context, to match reply w/ request
     @param domain_id - observation domain ID
     @param src_port - source port number
-    @param enable - 1 if enable, 0 if disable
+    @param enable - true if enable, false if disable
 */
 autoreply define nat_ipfix_enable_disable {
   u32 client_index;
   u32 context;
   u32 domain_id;
   u16 src_port;
-  u8 enable;
+  bool enable;
 };
 
 /** \brief Set NAT virtual fragmentation reassembly
@@ -161,7 +174,7 @@ autoreply define nat_ipfix_enable_disable {
     @param max_reass - maximum number of concurrent reassemblies
     @param max_frag - maximum number of fragmets per reassembly
     @param drop_frag - if 0 translate fragments, otherwise drop fragments
-    @param is_ip6 - 1 if IPv6, 0 if IPv4
+    @param is_ip6 - true if IPv6, false if IPv4
 */
 autoreply define nat_set_reass {
   u32 client_index;
@@ -170,7 +183,7 @@ autoreply define nat_set_reass {
   u16 max_reass;
   u8  max_frag;
   u8  drop_frag;
-  u8  is_ip6;
+  bool  is_ip6;
 };
 
 /** \brief Get NAT virtual fragmentation reassembly configuration
@@ -218,18 +231,16 @@ define nat_reass_dump {
 
 /** \brief NAT virtual fragmentation reassemblies response
     @param context - sender context, to match reply w/ request
-    @param is_ip4 - 1 if address type is IPv4
-    @param src_addr - source IP address
-    @param dst_addr - destination IP address
+    @param src_addr - source IPv4 address
+    @param dst_addr - destination IPv4 address
     @param frag_id - fragment ID
     @param proto - protocol
     @param frag_n - number of cached fragments
 */
 define nat_reass_details {
   u32 context;
-  u8 is_ip4;
-  u8 src_addr[16];
-  u8 dst_addr[16];
+  vl_api_address_t src_addr;
+  vl_api_address_t dst_addr;
   u32 frag_id;
   u8 proto;
   u8 frag_n;
@@ -337,13 +348,13 @@ define nat_get_addr_and_port_alloc_alg_reply {
     @param client_index - opaque cookie to identify the sender
     @param context - sender context, to match reply w/ request
     @param mss_value - MSS value to be used for MSS rewriting
-    @param enable - disable(0)/enable(1) MSS rewriting feature
+    @param enable - if true enable MSS rewriting feature else disable
 */
 autoreply define nat_set_mss_clamping {
   u32 client_index;
   u32 context;
   u16 mss_value;
-  u8 enable;
+  bool enable;
 };
 
 /** \brief Get TCP MSS rewriting configuration
@@ -359,13 +370,13 @@ define nat_get_mss_clamping {
     @param context - sender context, to match reply w/ request
     @param retval - return code
     @param mss_value - MSS value to be used for MSS rewriting
-    @param enable - disable(0)/enable(1) MSS rewriting feature
+    @param enable - if true enable MSS rewriting feature else disable
 */
 define nat_get_mss_clamping_reply {
   u32 context;
   i32 retval;
   u16 mss_value;
-  u8 enable;
+  bool enable;
 };
 
 /** \brief Set HA listener (local settings)
@@ -458,8 +469,8 @@ autoreply define nat_ha_flush {
 };
 
 /** \brief Resync HA (resend existing sessions to new failover)
+    @param client_index - opaque cookie to identify the sender
     @param context - sender context, to match reply w/ request
-    @param retval - return code
     @param want_resync_event - resync completed event sent to the sender via
                                nat_ha_resync_completed_event API message if
                                non-zero
@@ -499,17 +510,18 @@ service {
     @param first_ip_address - first IPv4 address
     @param last_ip_address - last IPv4 address
     @param vrf_id - VRF id of tenant, ~0 means independent of VRF
-    @param twice_nat - twice NAT address range for extenal hosts
-    @param is_add - 1 if add, 0 if delete
+    @param is_add - true if add, false if delete
+    @param flags - flag NAT_IS_TWICE_NAT if NAT address range for external hosts
+
 */
 autoreply define nat44_add_del_address_range {
   u32 client_index;
   u32 context;
-  u8 first_ip_address[4];
-  u8 last_ip_address[4];
+  vl_api_ip4_address_t first_ip_address;
+  vl_api_ip4_address_t last_ip_address;
   u32 vrf_id;
-  u8 twice_nat;
-  u8 is_add;
+  bool is_add;
+  vl_api_nat_config_flags_t flags;
 };
 
 /** \brief Dump NAT44 addresses
@@ -524,29 +536,30 @@ define nat44_address_dump {
 /** \brief NAT44 address details response
     @param context - sender context, to match reply w/ request
     @param ip_address - IPv4 address
-    @param twice_nat - twice NAT address range for extenal hosts
+    @param flags - flag NAT_IS_TWICE_NAT if NAT address range for external hosts
     @param vrf_id - VRF id of tenant, ~0 means independent of VRF
 */
 define nat44_address_details {
   u32 context;
-  u8 ip_address[4];
-  u8 twice_nat;
+  vl_api_ip4_address_t ip_address;
+  vl_api_nat_config_flags_t flags;
   u32 vrf_id;
 };
 
 /** \brief Enable/disable NAT44 feature on the interface
     @param client_index - opaque cookie to identify the sender
     @param context - sender context, to match reply w/ request
-    @param is_add - 1 if add, 0 if delete
-    @param is_inside - 1 if inside, 0 if outside
+    @param is_add - true if add, false if delete
+    @param flags - flag NAT_IS_INSIDE if interface is inside else
+                   interface is outside
     @param sw_if_index - software index of the interface
 */
 autoreply define nat44_interface_add_del_feature {
   u32 client_index;
   u32 context;
-  u8 is_add;
-  u8 is_inside;
-  u32 sw_if_index;
+  bool is_add;
+  vl_api_nat_config_flags_t flags;
+  vl_api_interface_index_t sw_if_index;
 };
 
 /** \brief Dump interfaces with NAT44 feature
@@ -560,29 +573,33 @@ define nat44_interface_dump {
 
 /** \brief NAT44 interface details response
     @param context - sender context, to match reply w/ request
-    @param is_inside - 1 if inside, 0 if outside, 2 if inside and outside
     @param sw_if_index - software index of the interface
+    @param flags - flag NAT_IS_INSIDE if interface is inside,
+                   flag NAT_IS_OUTSIDE if interface is outside
+                   and if both flags are set the interface is
+                   both inside and outside
 */
 define nat44_interface_details {
   u32 context;
-  u8 is_inside;
-  u32 sw_if_index;
+  vl_api_nat_config_flags_t flags;
+  vl_api_interface_index_t sw_if_index;
 };
 
 /** \brief Enable/disbale NAT44 as an interface output feature (postrouting
            in2out translation)
     @param client_index - opaque cookie to identify the sender
     @param context - sender context, to match reply w/ request
-    @param is_add - 1 if add, 0 if delete
-    @param is_inside - 1 if inside, 0 if outside
+    @param is_add - true if add, false if delete
+    @param flags - flag NAT_IS_INSIDE if interface is inside else
+                   interface is outside
     @param sw_if_index - software index of the interface
 */
 autoreply define nat44_interface_add_del_output_feature {
   u32 client_index;
   u32 context;
-  u8 is_add;
-  u8 is_inside;
-  u32 sw_if_index;
+  bool is_add;
+  vl_api_nat_config_flags_t flags;
+  vl_api_interface_index_t sw_if_index;
 };
 
 /** \brief Dump interfaces with NAT44 output feature
@@ -596,20 +613,26 @@ define nat44_interface_output_feature_dump {
 
 /** \brief NAT44 interface with output feature details response
     @param context - sender context, to match reply w/ request
-    @param is_inside - 1 if inside, 0 if outside
+    @param flags - flag NAT_IS_INSIDE if interface is inside else
+                   interface is outside
     @param sw_if_index - software index of the interface
 */
 define nat44_interface_output_feature_details {
   u32 context;
-  u8 is_inside;
-  u32 sw_if_index;
+  vl_api_nat_config_flags_t flags;
+  vl_api_interface_index_t sw_if_index;
 };
 
 /** \brief Add/delete NAT44 static mapping
     @param client_index - opaque cookie to identify the sender
     @param context - sender context, to match reply w/ request
-    @param is_add - 1 if add, 0 if delete
-    @param addr_only - 1 if address only mapping
+    @param is_add - true if add, false if delete
+    @param flags - flag NAT_IS_ADDR_ONLY if address only mapping,
+                   flag nat_is_twice_nat if nat address range for external hosts,
+                   flag NAT_IS_SELF_TWICE_NAT if translate external host address
+                   and port whenever external host address equals local
+                   address of internal host,
+                   flag NAT_IS_OUT2IN_ONLY if rule match only out2in direction
     @param local_ip_address - local IPv4 address
     @param external_ip_address - external IPv4 address
     @param protocol - IP protocol, used only if addr_only=0
@@ -619,30 +642,21 @@ define nat44_interface_output_feature_details {
                                   external_ip_address is ignored, ~0 means not
                                   used)
     @param vfr_id - VRF ID
-    @param twice_nat - if 1 translate external host address and port, only for
-                       1:1 NAPT (addr_only must be 0)
-    @param self_twice_nat - if 1 translate external host address and port
-                            whenever external host address equals
-                            local address of internal host
-    @param out2in_only - if 1 rule match only out2in direction
     @param tag - opaque string tag
 */
 autoreply define nat44_add_del_static_mapping {
   u32 client_index;
   u32 context;
-  u8 is_add;
-  u8 addr_only;
-  u8 local_ip_address[4];
-  u8 external_ip_address[4];
+  bool is_add;
+  vl_api_nat_config_flags_t flags;
+  vl_api_ip4_address_t local_ip_address;
+  vl_api_ip4_address_t external_ip_address;
   u8 protocol;
   u16 local_port;
   u16 external_port;
-  u32 external_sw_if_index;
+  vl_api_interface_index_t external_sw_if_index;
   u32 vrf_id;
-  u8 twice_nat;
-  u8 self_twice_nat;
-  u8 out2in_only;
-  u8 tag[64];
+  string tag;
 };
 
 /** \brief Dump NAT44 static mappings
@@ -656,42 +670,39 @@ define nat44_static_mapping_dump {
 
 /** \brief NAT44 static mapping details response
     @param context - sender context, to match reply w/ request
-    @param addr_only - 1 if address only mapping
+    @param flags - flag NAT_ADDR_ONLY if address only mapping,
+                   flag NAT_TWICE_NAT if NAT address range for external hosts,
+                   flag NAT_SELF_TWICE_NAT if translate external host address
+                   and port whenever external host address equals local
+                   address of internal host,
+                   flag NAT_OUT2IN_ONLY if rule match only out2in direction
     @param local_ip_address - local IPv4 address
     @param external_ip_address - external IPv4 address
-    @param protocol - IP protocol, valid only if addr_only=0
-    @param local_port - local port number, valid only if addr_only=0
-    @param external_port - external port number, valid only if addr_only=0
+    @param protocol - IP protocol, valid only if no NAT_ADDR_ONLY flag
+    @param local_port - local port number, valid only if no NAT_ADDR_ONLY flag
+    @param external_port - external port number, valid only if no NAT_ADDR_ONLY flag
     @param external_sw_if_index - external interface
     @param vfr_id - VRF ID
-    @param twice_nat - if 1 translate external host address and port
-    @param self_twice_nat - if 1 translate external host address and port
-                            whenever external host address equals
-                            local address of internal host
-    @param out2in_only - if 1 rule match only out2in direction
     @param tag - opaque string tag
 */
 define nat44_static_mapping_details {
   u32 context;
-  u8 addr_only;
-  u8 local_ip_address[4];
-  u8 external_ip_address[4];
+  vl_api_nat_config_flags_t flags;
+  vl_api_ip4_address_t local_ip_address;
+  vl_api_ip4_address_t external_ip_address;
   u8 protocol;
   u16 local_port;
   u16 external_port;
-  u32 external_sw_if_index;
+  vl_api_interface_index_t external_sw_if_index;
   u32 vrf_id;
-  u8 twice_nat;
-  u8 self_twice_nat;
-  u8 out2in_only;
-  u8 tag[64];
+  string tag;
 };
 
 /** \brief Add/delete NAT44 identity mapping
     @param client_index - opaque cookie to identify the sender
     @param context - sender context, to match reply w/ request
-    @param is_add - 1 if add, 0 if delete
-    @param addr_only - 1 if address only mapping
+    @param is_add - true if add, false if delete
+    @param flags - flag NAT_ADDR_ONLY if address only mapping
     @param ip_address - IPv4 address
     @param protocol - IP protocol
     @param port - port number
@@ -703,14 +714,14 @@ define nat44_static_mapping_details {
 autoreply define nat44_add_del_identity_mapping {
   u32 client_index;
   u32 context;
-  u8 is_add;
-  u8 addr_only;
-  u8 ip_address[4];
+  bool is_add;
+  vl_api_nat_config_flags_t flags;
+  vl_api_ip4_address_t ip_address;
   u8 protocol;
   u16 port;
-  u32 sw_if_index;
+  vl_api_interface_index_t sw_if_index;
   u32 vrf_id;
-  u8 tag[64];
+  string tag;
 };
 
 /** \brief Dump NAT44 identity mappings
@@ -724,7 +735,7 @@ define nat44_identity_mapping_dump {
 
 /** \brief NAT44 identity mapping details response
     @param context - sender context, to match reply w/ request
-    @param addr_only - 1 if address only mapping
+    @param flags - flag NAT_ADDR_ONLY if address only mapping
     @param ip_address - IPv4 address
     @param protocol - IP protocol
     @param port - port number
@@ -734,28 +745,28 @@ define nat44_identity_mapping_dump {
 */
 define nat44_identity_mapping_details {
   u32 context;
-  u8 addr_only;
-  u8 ip_address[4];
+  vl_api_nat_config_flags_t flags;
+  vl_api_ip4_address_t ip_address;
   u8 protocol;
   u16 port;
-  u32 sw_if_index;
+  vl_api_interface_index_t sw_if_index;
   u32 vrf_id;
-  u8 tag[64];
+  string tag;
 };
 
 /** \brief Add/delete NAT44 pool address from specific interfce
     @param client_index - opaque cookie to identify the sender
     @param context - sender context, to match reply w/ request
-    @param is_add - 1 if add, 0 if delete
-    @param twice_nat - twice NAT address for extenal hosts
+    @param is_add - true if add, false if delete
     @param sw_if_index - software index of the interface
+    @param flags - flag NAT_TWICE_NAT if NAT address range for external hosts
 */
 autoreply define nat44_add_del_interface_addr {
   u32 client_index;
   u32 context;
-  u8 is_add;
-  u8 twice_nat;
-  u32 sw_if_index;
+  bool is_add;
+  vl_api_interface_index_t sw_if_index;
+  vl_api_nat_config_flags_t flags;
 };
 
 /** \brief Dump NAT44 pool addresses interfaces
@@ -770,12 +781,13 @@ define nat44_interface_addr_dump {
 /** \brief NAT44 pool addresses interfaces details response
     @param context - sender context, to match reply w/ request
     @param sw_if_index - software index of the interface
-    @param twice_nat - twice NAT address for extenal hosts
+    @param flags - flag NAT_TWICE_NAT if NAT address range for external hosts
+
 */
 define nat44_interface_addr_details {
   u32 context;
-  u32 sw_if_index;
-  u8 twice_nat;
+  vl_api_interface_index_t sw_if_index;
+  vl_api_nat_config_flags_t flags;
 };
 
 /** \brief Dump NAT44 users
@@ -790,14 +802,14 @@ define nat44_user_dump {
 /** \brief NAT44 users response
     @param context - sender context, to match reply w/ request
     @vrf_id - VRF ID
-    @param ip_adress - IPv4 address
+    @param ip_address - IPv4 address
     @param nsessions - number of dynamic sessions
     @param nstaticsessions - number of static sessions
 */
 define nat44_user_details {
   u32 context;
   u32 vrf_id;
-  u8 ip_address[4];
+  vl_api_ip4_address_t ip_address;
   u32 nsessions;
   u32 nstaticsessions;
 };
@@ -805,14 +817,13 @@ define nat44_user_details {
 /** \brief NAT44 user's sessions
     @param client_index - opaque cookie to identify the sender
     @param context - sender context, to match reply w/ request
-    @param is_ip4 - 1 if address type is IPv4
-    @param user_ip - IP address of the user to dump
+    @param ip_address - IPv4 address of the user to dump
     @param vrf_id - VRF_ID
 */
 define nat44_user_session_dump {
   u32 client_index;
   u32 context;
-  u8 ip_address[4];
+  vl_api_ip4_address_t ip_address;
   u32 vrf_id;
 };
 
@@ -823,12 +834,13 @@ define nat44_user_session_dump {
     @param inside_ip_address - inside IPv4 address
     @param inside_port - inside port
     @param protocol - protocol
-    @param is_static - 1 if session is static
+    @param flags - flag NAT_IS_STATIC if session is static,
+                   flag NAT_IS_TWICE_NAT if session is twice-nat,
+                   flag NAT_IS_EXT_HOST_VALID if external host address
+                   and port are valid
     @param last_heard - last heard timer
     @param total_bytes - count of bytes sent through session
     @param total_pkts - count of pakets sent through session
-    @param is_twicenat - 1 if session is twice-nat
-    @param ext_host_valid - 1 if external host address and port are valid
     @param ext_host_address - external host IPv4 address
     @param ext_host_port - external host port
     @param ext_host_nat_address - post-NAT external host IPv4 address (valid
@@ -838,20 +850,18 @@ define nat44_user_session_dump {
 */
 define nat44_user_session_details {
   u32 context;
-  u8 outside_ip_address[4];
+  vl_api_ip4_address_t outside_ip_address;
   u16 outside_port;
-  u8 inside_ip_address[4];
+  vl_api_ip4_address_t inside_ip_address;
   u16 inside_port;
   u16 protocol;
-  u8 is_static;
+  vl_api_nat_config_flags_t flags;
   u64 last_heard;
   u64 total_bytes;
   u32 total_pkts;
-  u8 is_twicenat;
-  u8 ext_host_valid;
-  u8 ext_host_address[4];
+  vl_api_ip4_address_t ext_host_address;
   u16 ext_host_port;
-  u8 ext_host_nat_address[4];
+  vl_api_ip4_address_t ext_host_nat_address;
   u16 ext_host_nat_port;
 };
 
@@ -859,9 +869,10 @@ define nat44_user_session_details {
     @param addr - IPv4 address of the internal node
     @param port - L4 port number of the internal node
     @param probability - probability of the internal node to be randomly matched
+    @param vrf_id - VRF id
 */
 typeonly manual_endian define nat44_lb_addr_port {
-  u8 addr[4];
+  vl_api_ip4_address_t addr;
   u16 port;
   u8 probability;
   u32 vrf_id;
@@ -870,41 +881,39 @@ typeonly manual_endian define nat44_lb_addr_port {
 /** \brief Add/delete NAT44 load-balancing static mapping rule
     @param client_index - opaque cookie to identify the sender
     @param context - sender context, to match reply w/ request
-    @param is_add - 1 if add, 0 if delete
+    @param is_add - true if add, false if delete
+    @param flags - flag NAT_TWICE_NAT if NAT address range for external hosts,
+                   flag NAT_SELF_TWICE_NAT if translate external host address
+                   and port whenever external host address equals local
+                   address of internal host,
+                   flag NAT_OUT2IN_ONLY if rule match only out2in direction
     @param external_addr - external IPv4 address of the service
     @param external_port - external L4 port number of the service
     @param protocol - IP protocol number of the service
-    @param twice_nat - if 1 translate external host address and port
-    @param self_twice_nat - if 1 translate external host address and port
-                            whenever external host address equals
-                            local address of internal host
-    @param out2in_only - if 1 rule match only out2in direction
-    @param tag - opaque string tag
     @param affinity - if 0 disabled, otherwise client IP affinity sticky time
                       in seconds
     @param local_num - number of local network nodes
     @param locals - local network nodes
+    @param tag - opaque string tag
 */
 autoreply manual_endian define nat44_add_del_lb_static_mapping {
   u32 client_index;
   u32 context;
-  u8 is_add;
-  u8 external_addr[4];
+  bool is_add;
+  vl_api_nat_config_flags_t flags;
+  vl_api_ip4_address_t external_addr;
   u16 external_port;
   u8 protocol;
-  u8 twice_nat;
-  u8 self_twice_nat;
-  u8 out2in_only;
-  u8 tag[64];
   u32 affinity;
   u32 local_num;
   vl_api_nat44_lb_addr_port_t locals[local_num];
+  string tag;
 };
 
 /** \brief Add/delete NAT44 load-balancing static mapping rule backend
     @param client_index - opaque cookie to identify the sender
     @param context - sender context, to match reply w/ request
-    @param is_add - 1 if add, 0 if delete
+    @param is_add - true if add, false if delete
     @param external_addr - external IPv4 address of the service
     @param external_port - external L4 port number of the service
     @param protocol - IP protocol number of the service
@@ -913,8 +922,8 @@ autoreply manual_endian define nat44_add_del_lb_static_mapping {
 autoreply define nat44_lb_static_mapping_add_del_local {
   u32 client_index;
   u32 context;
-  u8 is_add;
-  u8 external_addr[4];
+  bool is_add;
+  vl_api_ip4_address_t external_addr;
   u16 external_port;
   u8 protocol;
   vl_api_nat44_lb_addr_port_t local;
@@ -931,57 +940,55 @@ define nat44_lb_static_mapping_dump {
 
 /** \brief NAT44 load-balancing static mapping rule details response
     @param context - sender context, to match reply w/ request
-    @param is_add - 1 if add, 0 if delete
     @param external_addr - external IPv4 address of the service
     @param external_port - external L4 port number of the service
     @param protocol - IP protocol number of the service
-    @param twice_nat - if 1 translate external host address and port
-    @param self_twice_nat - if 1 translate external host address and port
-                            whenever external host address equals
-                            local address of internal host
-    @param out2in_only - if 1 rule match only out2in direction
-    @param tag - opaque string tag
+    @param flags - flag NAT_TWICE_NAT if NAT address range for external hosts,
+                   flag NAT_SELF_TWICE_NAT if translate external host address
+                   and port whenever external host address equals local
+                   address of internal host,
+                   flag NAT_OUT2IN_ONLY if rule match only out2in direction
     @param affinity - if 0 disabled, otherwise client IP affinity sticky time
                       in seconds
     @param local_num - number of local network nodes
     @param locals - local network nodes
+    @param tag - opaque string tag
 */
 manual_endian define nat44_lb_static_mapping_details {
   u32 context;
-  u8 external_addr[4];
+  vl_api_ip4_address_t external_addr;
   u16 external_port;
   u8 protocol;
-  u8 twice_nat;
-  u8 self_twice_nat;
-  u8 out2in_only;
-  u8 tag[64];
+  vl_api_nat_config_flags_t flags;
   u32 affinity;
   u32 local_num;
   vl_api_nat44_lb_addr_port_t locals[local_num];
+  string tag;
 };
 
 /** \brief Delete NAT44 session
     @param client_index - opaque cookie to identify the sender
     @param context - sender context, to match reply w/ request
-    @param is_in - 1 if inside network address and port pair, 0 if outside
     @param ip_address - IPv4 address
     @param protocol - IP protocol
     @param port - port number
     @param vfr_id - VRF ID
-    @param ext_host_valid - 1 if external host address and port are valid
+    @param flags - flag NAT_IS_INSIDE if interface is inside or
+                   interface is outside,
+                   flag NAT_IS_EXT_HOST_VALID if external host address and
+                   port are valid
     @param ext_host_address - external host IPv4 address
     @param ext_host_port - external host port
 */
 autoreply define nat44_del_session {
   u32 client_index;
   u32 context;
-  u8 is_in;
-  u8 address[4];
+  vl_api_ip4_address_t address;
   u8 protocol;
   u16 port;
   u32 vrf_id;
-  u8 ext_host_valid;
-  u8 ext_host_address[4];
+  vl_api_nat_config_flags_t flags;
+  vl_api_ip4_address_t ext_host_address;
   u16 ext_host_port;
 };
 
@@ -990,12 +997,12 @@ autoreply define nat44_del_session {
     or static mapping instead of dropping them.
     @param client_index - opaque cookie to identify the sender
     @param context - sender context, to match reply w/ request
-    @param enable - 0 for enable, 1 for disable
+    @param enable - true for enable, false for disable
 */
 autoreply define nat44_forwarding_enable_disable {
   u32 client_index;
   u32 context;
-  u8 enable;
+  bool enable;
 };
 
 /** \brief Check if forwarding is enabled or disabled
@@ -1009,11 +1016,11 @@ define nat44_forwarding_is_enabled {
 
 /** \brief Response to check if forwarding is enabled or disabled
     @param context - sender context, to match reply w/ request
-    @param enabled - 1 if enabled, 0 if disabled
+    @param enabled - true if enabled, false if disabled
 */
 define nat44_forwarding_is_enabled_reply {
   u32 context;
-  u8 enabled;
+  bool enabled;
 };
 
 
@@ -1024,36 +1031,31 @@ define nat44_forwarding_is_enabled_reply {
 /** \brief Add/delete NAT deterministic mapping
     @param client_index - opaque cookie to identify the sender
     @param context - sender context, to match reply w/ request
-    @param is_add - 1 if add, 0 if delete
-    @param is_nat44 - 1 if NAT44
-    @param in_addr - inside IP address
-    @param in_plen - inside IP address prefix length
+    @param is_add - true if add, false if delete
+    @param in_addr - inside IPv4 address
+    @param in_plen - inside IPv4 address prefix length
     @param out_addr - outside IPv4 address
-    @param out_addr - outside IPv4 address prefix length
+    @param out_plen - outside IPv4 address prefix length
 */
 autoreply define nat_det_add_del_map {
   u32 client_index;
   u32 context;
-  u8 is_add;
-  u8 is_nat44;
-  u8 addr_only;
-  u8 in_addr[16];
+  bool is_add;
+  vl_api_ip4_address_t in_addr;
   u8 in_plen;
-  u8 out_addr[4];
+  vl_api_ip4_address_t out_addr;
   u8 out_plen;
 };
 
 /** \brief Get outside address and port range from inside address
     @param client_index - opaque cookie to identify the sender
     @param context - sender context, to match reply w/ request
-    @param is_nat44 - 1 if NAT44
     @param in_addr - inside IP address
 */
 define nat_det_forward {
   u32 client_index;
   u32 context;
-  u8 is_nat44;
-  u8 in_addr[16];
+  vl_api_ip4_address_t in_addr;
 };
 
 /** \brief Get outside address and port range from inside address
@@ -1068,7 +1070,7 @@ define nat_det_forward_reply {
   i32 retval;
   u16 out_port_lo;
   u16 out_port_hi;
-  u8 out_addr[4];
+  vl_api_ip4_address_t out_addr;
 };
 
 /** \brief Get inside address from outside address and port
@@ -1081,20 +1083,18 @@ define nat_det_reverse {
   u32 client_index;
   u32 context;
   u16 out_port;
-  u8 out_addr[4];
+  vl_api_ip4_address_t out_addr;
 };
 
 /** \brief Get inside address from outside address and port reply
     @param context - sender context, to match reply w/ request
     @param retval - return code
-    @param is_nat44 - 1 if NAT44
     @param in_addr - inside IP address
 */
 define nat_det_reverse_reply {
   u32 context;
   i32 retval;
-  u8 is_nat44;
-  u8 in_addr[16];
+  vl_api_ip4_address_t in_addr;
 };
 
 /** \brief Dump NAT deterministic mappings
@@ -1108,9 +1108,8 @@ define nat_det_map_dump {
 
 /** \brief NAT users response
     @param context - sender context, to match reply w/ request
-    @param is_nat44 - 1 if NAT44
-    @param in_addr - inside IP address
-    @param in_plen - inside IP address prefix length
+    @param in_addr - inside IPv4 address
+    @param in_plen - inside IPv4 address prefix length
     @param out_addr - outside IPv4 address
     @param out_plen - outside IPv4 address prefix length
     @param sharing_ratio - outside to inside address sharing ratio
@@ -1119,10 +1118,9 @@ define nat_det_map_dump {
 */
 define nat_det_map_details {
   u32 context;
-  u8 is_nat44;
-  u8 in_addr[16];
+  vl_api_ip4_address_t in_addr;
   u8 in_plen;
-  u8 out_addr[4];
+  vl_api_ip4_address_t out_addr;
   u8 out_plen;
   u32 sharing_ratio;
   u16 ports_per_host;
@@ -1140,16 +1138,15 @@ define nat_det_map_details {
 autoreply define nat_det_close_session_out {
   u32 client_index;
   u32 context;
-  u8 out_addr[4];
+  vl_api_ip4_address_t out_addr;
   u16 out_port;
-  u8 ext_addr[4];
+  vl_api_ip4_address_t ext_addr;
   u16 ext_port;
 };
 
 /** \brief Close deterministic NAT session by inside address and port
     @param client_index - opaque cookie to identify the sender
     @param context - sender context, to match reply w/ request
-    @param is_nat44 - 1 if NAT44
     @param in_addr - inside IP address
     @param in_port - inside port
     @param ext_addr - external host IP address
@@ -1158,30 +1155,27 @@ autoreply define nat_det_close_session_out {
 autoreply define nat_det_close_session_in {
   u32 client_index;
   u32 context;
-  u8 is_nat44;
-  u8 in_addr[16];
+  vl_api_ip4_address_t in_addr;
   u16 in_port;
-  u8 ext_addr[16];
+  vl_api_ip4_address_t ext_addr;
   u16 ext_port;
 };
 
 /** \brief Dump determinstic NAT sessions
     @param client_index - opaque cookie to identify the sender
     @param context - sender context, to match reply w/ request
-    @param is_nat44 - 1 if NAT44
     @param user_addr - address of an inside user whose sessions to dump
 */
 define nat_det_session_dump {
   u32 client_index;
   u32 context;
-  u8 is_nat44;
-  u8 user_addr[16];
+  vl_api_ip4_address_t user_addr;
 };
 
 /** \brief Deterministic NAT sessions reply
     @param context - sender context, to match reply w/ request
     @param in_port - inside port
-    @param ext_addr - external host address
+    @param ext_addr - external host IPv4 address
     @param ext_port - external host port
     @param out_port - outside NAT port
     @param state - session state
@@ -1190,7 +1184,7 @@ define nat_det_session_dump {
 define nat_det_session_details {
   u32 context;
   u16 in_port;
-  u8 ext_addr[4];
+  vl_api_ip4_address_t ext_addr;
   u16 ext_port;
   u16 out_port;
   u8 state;
@@ -1204,18 +1198,18 @@ define nat_det_session_details {
 /** \brief Add/delete address range to NAT64 pool
     @param client_index - opaque cookie to identify the sender
     @param context - sender context, to match reply w/ request
-    @param start_addr - start address of the range
-    @param end_addr - end address of the range
+    @param start_addr - start IPv4 address of the range
+    @param end_addr - end IPv4 address of the range
     @param vrf_id - VRF id of tenant, ~0 means independent of VRF
-    @param is_add - 1 if add, 0 if delete
+    @param is_add - true if add, false if delete
 */
 autoreply define nat64_add_del_pool_addr_range {
   u32 client_index;
   u32 context;
-  u8 start_addr[4];
-  u8 end_addr[4];
+  vl_api_ip4_address_t start_addr;
+  vl_api_ip4_address_t end_addr;
   u32 vrf_id;
-  u8 is_add;
+  bool is_add;
 };
 
 /** \brief Dump NAT64 pool addresses
@@ -1234,23 +1228,24 @@ define nat64_pool_addr_dump {
 */
 define nat64_pool_addr_details {
   u32 context;
-  u8 address[4];
+  vl_api_ip4_address_t address;
   u32 vrf_id;
 };
 
 /** \brief Enable/disable NAT64 feature on the interface
     @param client_index - opaque cookie to identify the sender
     @param context - sender context, to match reply w/ request
+    @param is_add - true if add, false if delete
+    @param flags - flag NAT_IS_INSIDE if interface is inside else
+                   interface is outside
     @param sw_if_index - index of the interface
-    @param is_inside - 1 if inside, 0 if outside
-    @param is_add - 1 if add, 0 if delete
 */
 autoreply define nat64_add_del_interface {
   u32 client_index;
   u32 context;
-  u32 sw_if_index;
-  u8 is_inside;
-  u8 is_add;
+  bool is_add;
+  vl_api_nat_config_flags_t flags;
+  vl_api_interface_index_t sw_if_index;
 };
 
 /** \brief Dump interfaces with NAT64 feature
@@ -1264,13 +1259,16 @@ define nat64_interface_dump {
 
 /** \brief NAT64 interface details response
     @param context - sender context, to match reply w/ request
-    @param is_inside - 1 if inside, 0 if outside
+    @param flags - flag NAT_IS_INSIDE if interface is inside,
+                   flag NAT_IS_OUTSIDE if interface is outside
+                   and if both flags are set the interface is
+                   both inside and outside
     @param sw_if_index - index of the interface
 */
 define nat64_interface_details {
   u32 context;
-  u8 is_inside;
-  u32 sw_if_index;
+  vl_api_nat_config_flags_t flags;
+  vl_api_interface_index_t sw_if_index;
 };
 
 /** \brief Add/delete NAT64 static BIB entry
@@ -1282,18 +1280,18 @@ define nat64_interface_details {
     @param o_port - outside port number
     @param vrf_id - VRF id of tenant
     @param proto - protocol number
-    @param is_add - 1 if add, 0 if delete
+    @param is_add - true if add, false if delete
 */
  autoreply define nat64_add_del_static_bib {
   u32 client_index;
   u32 context;
-  u8 i_addr[16];
-  u8 o_addr[4];
+  vl_api_ip6_address_t i_addr;
+  vl_api_ip4_address_t o_addr;
   u16 i_port;
   u16 o_port;
   u32 vrf_id;
   u8 proto;
-  u8 is_add;
+  bool is_add;
 };
 
 /** \brief Dump NAT64 BIB
@@ -1319,18 +1317,19 @@ define nat64_bib_dump {
     @param o_port - outside port number
     @param vrf_id - VRF id of tenant
     @param proto - protocol number
-    @param is_static - 1 if static BIB entry, 0 if dynamic
+    @param flags - flag NAT_IS_STATIC if BIB entry is static 
+                   or BIB entry is dynamic
     @param ses_num - number of sessions associated with the BIB entry
 */
 define nat64_bib_details {
   u32 context;
-  u8 i_addr[16];
-  u8 o_addr[4];
+  vl_api_ip6_address_t i_addr;
+  vl_api_ip4_address_t o_addr;
   u16 i_port;
   u16 o_port;
   u32 vrf_id;
   u8 proto;
-  u8 is_static;
+  vl_api_nat_config_flags_t flags;
   u32 ses_num;
 };
 
@@ -1355,20 +1354,20 @@ define nat64_st_dump {
     @param ol_addr - outside IPv4 address of the local host
     @param il_port - inside port number id of the local host/inside ICMP id
     @param ol_port - outside port number of the local host/outside ICMP id
-    @param il_addr - inside IPv6 address of the remote host
-    @param ol_addr - outside IPv4 address of the remote host
-    @param l_port - port number of the remote host (not used for ICMP)
+    @param ir_addr - inside IPv6 address of the remote host
+    @param or_addr - outside IPv4 address of the remote host
+    @param r_port - port number of the remote host (not used for ICMP)
     @param vrf_id - VRF id of tenant
     @param proto - protocol number
 */
 define nat64_st_details {
   u32 context;
-  u8 il_addr[16];
-  u8 ol_addr[4];
+  vl_api_ip6_address_t il_addr;
+  vl_api_ip4_address_t ol_addr;
   u16 il_port;
   u16 ol_port;
-  u8 ir_addr[16];
-  u8 or_addr[4];
+  vl_api_ip6_address_t ir_addr;
+  vl_api_ip4_address_t or_addr;
   u16 r_port;
   u32 vrf_id;
   u8 proto;
@@ -1378,17 +1377,15 @@ define nat64_st_details {
     @param client_index - opaque cookie to identify the sender
     @param context - sender context, to match reply w/ request
     @param prefix - NAT64 prefix
-    @param prefix - NAT64 prefix length
     @param vrf_id - VRF id of tenant
-    @param is_add - 1 if add, 0 if delete
+    @param is_add - true if add, false if delete
 */
 autoreply define nat64_add_del_prefix {
   u32 client_index;
   u32 context;
-  u8 prefix[16];
-  u8 prefix_len;
+  vl_api_ip6_prefix_t prefix;
   u32 vrf_id;
-  u8 is_add;
+  bool is_add;
 };
 
 /** \brief Dump NAT64 prefix
@@ -1403,31 +1400,27 @@ define nat64_prefix_dump {
 /** \brief Dump NAT64 prefix details response
     @param context - sender context, to match reply w/ request
     @param prefix - NAT64 prefix
-    @param prefix - NAT64 prefix length
     @param vrf_id - VRF id of tenant
 */
 define nat64_prefix_details {
   u32 context;
-  u8 prefix[16];
-  u8 prefix_len;
+  vl_api_ip6_prefix_t prefix;
   u32 vrf_id;
 };
 
 /** \brief Add/delete NAT64 pool address from specific interfce
     @param client_index - opaque cookie to identify the sender
     @param context - sender context, to match reply w/ request
-    @param is_add - 1 if add, 0 if delete
+    @param is_add - true if add, false if delete
     @param sw_if_index - software index of the interface
 */
 autoreply define nat64_add_del_interface_addr {
   u32 client_index;
   u32 context;
-  u8 is_add;
-  u8 is_inside;
-  u32 sw_if_index;
+  bool is_add;
+  vl_api_interface_index_t sw_if_index;
 };
 
-
 /*
  * DS-Lite APIs
  */
@@ -1435,16 +1428,16 @@ autoreply define nat64_add_del_interface_addr {
 /** \brief Add/delete address range to DS-Lite pool
     @param client_index - opaque cookie to identify the sender
     @param context - sender context, to match reply w/ request
-    @param start_addr - start address of the range
-    @param end_addr - end address of the range
-    @param is_add - 1 if add, 0 if delete
+    @param start_addr - start IPv4 address of the range
+    @param end_addr - end IPv4 address of the range
+    @param is_add - true if add, false if delete
 */
 autoreply define dslite_add_del_pool_addr_range {
   u32 client_index;
   u32 context;
-  u8 start_addr[4];
-  u8 end_addr[4];
-  u8 is_add;
+  vl_api_ip4_address_t start_addr;
+  vl_api_ip4_address_t end_addr;
+  bool is_add;
 };
 
 /** \brief Dump DS-Lite addresses
@@ -1462,20 +1455,20 @@ define dslite_address_dump {
 */
 define dslite_address_details {
   u32 context;
-  u8 ip_address[4];
+  vl_api_ip4_address_t ip_address;
 };
 
 /** \brief Set AFTR IPv6 and IPv4 addresses
     @param client_index - opaque cookie to identify the sender
     @param context - sender context, to match reply w/ request
     @param ip4_addr - IPv4 address
-    @param ip6_addr - IP64 address
+    @param ip6_addr - IPv6 address
 */
 autoreply define dslite_set_aftr_addr {
   u32 client_index;
   u32 context;
-  u8 ip4_addr[4];
-  u8 ip6_addr[16];
+  vl_api_ip4_address_t ip4_addr;
+  vl_api_ip6_address_t ip6_addr;
 };
 
 /** \brief Get AFTR IPv6 and IPv4 addresses
@@ -1491,26 +1484,26 @@ define dslite_get_aftr_addr {
     @param context - sender context, to match reply w/ request
     @param retval - return code
     @param ip4_addr - IPv4 address
-    @param ip6_addr - IP64 address
+    @param ip6_addr - IPv6 address
 */
 define dslite_get_aftr_addr_reply {
   u32 context;
   i32 retval;
-  u8 ip4_addr[4];
-  u8 ip6_addr[16];
+  vl_api_ip4_address_t ip4_addr;
+  vl_api_ip6_address_t ip6_addr;
 };
 
 /** \brief Set B4 IPv6 and IPv4 addresses
     @param client_index - opaque cookie to identify the sender
     @param context - sender context, to match reply w/ request
     @param ip4_addr - IPv4 address
-    @param ip6_addr - IP64 address
+    @param ip6_addr - IPv6 address
 */
 autoreply define dslite_set_b4_addr {
   u32 client_index;
   u32 context;
-  u8 ip4_addr[4];
-  u8 ip6_addr[16];
+  vl_api_ip4_address_t ip4_addr;
+  vl_api_ip6_address_t ip6_addr;
 };
 
 /** \brief Get B4 IPv6 and IPv4 addresses
@@ -1526,13 +1519,13 @@ define dslite_get_b4_addr {
     @param context - sender context, to match reply w/ request
     @param retval - return code
     @param ip4_addr - IPv4 address
-    @param ip6_addr - IP64 address
+    @param ip6_addr - IPv6 address
 */
 define dslite_get_b4_addr_reply {
   u32 context;
   i32 retval;
-  u8 ip4_addr[4];
-  u8 ip6_addr[16];
+  vl_api_ip4_address_t ip4_addr;
+  vl_api_ip6_address_t ip6_addr;
 };
 
 /*
@@ -1541,16 +1534,17 @@ define dslite_get_b4_addr_reply {
 /** \brief Enable/disable NAT66 feature on the interface
     @param client_index - opaque cookie to identify the sender
     @param context - sender context, to match reply w/ request
-    @param is_add - 1 if add, 0 if delete
-    @param is_inside - 1 if inside, 0 if outside
+    @param is_add - true if add, false if delete
+    @param flags - flag NAT_IS_INSIDE if interface is inside or
+                   interface is outside,
     @param sw_if_index - software index of the interface
 */
 autoreply define nat66_add_del_interface {
   u32 client_index;
   u32 context;
-  u8 is_add;
-  u8 is_inside;
-  u32 sw_if_index;
+  bool is_add;
+  vl_api_nat_config_flags_t flags;
+  vl_api_interface_index_t sw_if_index;
 };
 
 /** \brief Dump interfaces with NAT66 feature
@@ -1564,19 +1558,20 @@ define nat66_interface_dump {
 
 /** \brief NAT66 interface details response
     @param context - sender context, to match reply w/ request
-    @param is_inside - 1 if inside, 0 if outside
+    @param flags - flag NAT_IS_INSIDE if interface is inside or
+                   interface is outside,
     @param sw_if_index - software index of the interface
 */
 define nat66_interface_details {
   u32 context;
-  u8 is_inside;
-  u32 sw_if_index;
+  vl_api_nat_config_flags_t flags;
+  vl_api_interface_index_t sw_if_index;
 };
 
 /** \brief Add/delete 1:1 NAT66
     @param client_index - opaque cookie to identify the sender
     @param context - sender context, to match reply w/ request
-    @param is_add - 1 if add, 0 if delete
+    @param is_add - true if add, false if delete
     @param local_ip_address - local IPv6 address
     @param external_ip_address - external IPv6 address
     @param vrf_id - VRF id of tenant
@@ -1584,9 +1579,9 @@ define nat66_interface_details {
 autoreply define nat66_add_del_static_mapping {
   u32 client_index;
   u32 context;
-  u8 is_add;
-  u8 local_ip_address[16];
-  u8 external_ip_address[16];
+  bool is_add;
+  vl_api_ip6_address_t local_ip_address;
+  vl_api_ip6_address_t external_ip_address;
   u32 vrf_id;
 };
 
@@ -1609,8 +1604,8 @@ define nat66_static_mapping_dump {
 */
 define nat66_static_mapping_details {
   u32 context;
-  u8 local_ip_address[16];
-  u8 external_ip_address[16];
+  vl_api_ip6_address_t local_ip_address;
+  vl_api_ip6_address_t external_ip_address;
   u32 vrf_id;
   u64 total_bytes;
   u64 total_pkts;
diff --git a/src/plugins/nat/nat.h b/src/plugins/nat/nat.h
index ca2d1fcf1bf..237d945a724 100644
--- a/src/plugins/nat/nat.h
+++ b/src/plugins/nat/nat.h
@@ -110,6 +110,24 @@ typedef struct
   u8 cached;
 } nat44_reass_trace_t;
 
+/* NAT API Configuration flags */
+#define foreach_nat_config_flag \
+  _(0x01, IS_TWICE_NAT)         \
+  _(0x02, IS_SELF_TWICE_NAT)    \
+  _(0x04, IS_OUT2IN_ONLY)       \
+  _(0x08, IS_ADDR_ONLY)         \
+  _(0x10, IS_OUTSIDE)           \
+  _(0x20, IS_INSIDE)            \
+  _(0x40, IS_STATIC)            \
+  _(0x80, IS_EXT_HOST_VALID)    \
+
+typedef enum nat_config_flags_t_
+{
+#define _(n,f) NAT_API_##f = n,
+  foreach_nat_config_flag
+#undef _
+} nat_config_flags_t;
+
 /* External address and port allocation modes */
 #define foreach_nat_addr_and_port_alloc_alg \
   _(0, DEFAULT, "default")         \
diff --git a/src/plugins/nat/nat_api.c b/src/plugins/nat/nat_api.c
index 21b2cd44880..5c6d957a708 100644
--- a/src/plugins/nat/nat_api.c
+++ b/src/plugins/nat/nat_api.c
@@ -31,6 +31,7 @@
 
 #include <nat/nat_msg_enum.h>
 #include <vnet/fib/fib_table.h>
+#include <vnet/ip/ip_types_api.h>
 
 #define vl_api_nat44_lb_addr_port_t_endian vl_noop_handler
 #define vl_api_nat44_add_del_lb_static_mapping_t_endian vl_noop_handler
@@ -63,7 +64,6 @@
     vec_free (s);                               \
     return handle;
 
-
 /******************************/
 /*** Common NAT plugin APIs ***/
 /******************************/
@@ -201,14 +201,20 @@ send_nat_worker_details (u32 worker_index, vl_api_registration_t * reg,
   snat_main_t *sm = &snat_main;
   vlib_worker_thread_t *w =
     vlib_worker_threads + worker_index + sm->first_worker_index;
+  u32 len = vec_len (w->name);
 
-  rmp = vl_msg_api_alloc (sizeof (*rmp));
-  clib_memset (rmp, 0, sizeof (*rmp));
+  if (len)
+    --len;
+
+  rmp = vl_msg_api_alloc (sizeof (*rmp) + len);
+  clib_memset (rmp, 0, sizeof (*rmp) + len);
   rmp->_vl_msg_id = ntohs (VL_API_NAT_WORKER_DETAILS + sm->msg_id_base);
   rmp->context = context;
   rmp->worker_index = htonl (worker_index);
   rmp->lcore_id = htonl (w->cpu_id);
-  strncpy ((char *) rmp->name, (char *) w->name, ARRAY_LEN (rmp->name) - 1);
+
+  if (len)
+    vl_api_to_api_string (len, (char *) w->name, &rmp->name);
 
   vl_api_send_msg (reg, (u8 *) rmp);
 }
@@ -349,17 +355,22 @@ nat_ip4_reass_walk_api (nat_reass_ip4_t * reass, void *arg)
   vl_api_nat_reass_details_t *rmp;
   snat_main_t *sm = &snat_main;
   nat_api_walk_ctx_t *ctx = arg;
+  ip46_address_t ip_address;
 
   rmp = vl_msg_api_alloc (sizeof (*rmp));
   clib_memset (rmp, 0, sizeof (*rmp));
   rmp->_vl_msg_id = ntohs (VL_API_NAT_REASS_DETAILS + sm->msg_id_base);
   rmp->context = ctx->context;
-  clib_memcpy (rmp->src_addr, &(reass->key.src), 4);
-  clib_memcpy (rmp->dst_addr, &(reass->key.dst), 4);
+
+  clib_memcpy (&ip_address.ip4, &reass->key.src, 4);
+  ip_address_encode (&ip_address, IP46_TYPE_IP4, &rmp->src_addr);
+
+  clib_memcpy (&ip_address.ip4, &reass->key.dst, 4);
+  ip_address_encode (&ip_address, IP46_TYPE_IP4, &rmp->dst_addr);
+
   rmp->proto = reass->key.proto;
   rmp->frag_id = ntohl (reass->key.frag_id);
   rmp->frag_n = reass->frag_n;
-  rmp->is_ip4 = 1;
 
   vl_api_send_msg (ctx->reg, (u8 *) rmp);
 
@@ -372,17 +383,22 @@ nat_ip6_reass_walk_api (nat_reass_ip6_t * reass, void *arg)
   vl_api_nat_reass_details_t *rmp;
   snat_main_t *sm = &snat_main;
   nat_api_walk_ctx_t *ctx = arg;
+  ip46_address_t ip_address;
 
   rmp = vl_msg_api_alloc (sizeof (*rmp));
   clib_memset (rmp, 0, sizeof (*rmp));
   rmp->_vl_msg_id = ntohs (VL_API_NAT_REASS_DETAILS + sm->msg_id_base);
   rmp->context = ctx->context;
-  clib_memcpy (rmp->src_addr, &(reass->key.src), 16);
-  clib_memcpy (rmp->dst_addr, &(reass->key.dst), 16);
+
+  clib_memcpy (&ip_address.ip6, &reass->key.src, 16);
+  ip_address_encode (&ip_address, IP46_TYPE_IP6, &rmp->src_addr);
+
+  clib_memcpy (&ip_address.ip6, &reass->key.dst, 16);
+  ip_address_encode (&ip_address, IP46_TYPE_IP6, &rmp->dst_addr);
+
   rmp->proto = reass->key.proto;
   rmp->frag_id = ntohl (reass->key.frag_id);
   rmp->frag_n = reass->frag_n;
-  rmp->is_ip4 = 0;
 
   vl_api_send_msg (ctx->reg, (u8 *) rmp);
 
@@ -838,6 +854,7 @@ static void
   snat_main_t *sm = &snat_main;
   vl_api_nat44_add_del_address_range_reply_t *rmp;
   ip4_address_t this_addr;
+  u8 is_add, twice_nat;
   u32 start_host_order, end_host_order;
   u32 vrf_id;
   int i, count;
@@ -856,6 +873,9 @@ static void
       goto send_reply;
     }
 
+  is_add = mp->is_add;
+  twice_nat = mp->flags & NAT_API_IS_TWICE_NAT;
+
   tmp = (u32 *) mp->first_ip_address;
   start_host_order = clib_host_to_net_u32 (tmp[0]);
   tmp = (u32 *) mp->last_ip_address;
@@ -874,16 +894,16 @@ static void
 
   for (i = 0; i < count; i++)
     {
-      if (mp->is_add)
-	rv = snat_add_address (sm, &this_addr, vrf_id, mp->twice_nat);
+      if (is_add)
+	rv = snat_add_address (sm, &this_addr, vrf_id, twice_nat);
       else
-	rv = snat_del_address (sm, this_addr, 0, mp->twice_nat);
+	rv = snat_del_address (sm, this_addr, 0, twice_nat);
 
       if (rv)
 	goto send_reply;
 
       if (sm->out2in_dpo)
-	nat44_add_del_address_dpo (this_addr, mp->is_add);
+	nat44_add_del_address_dpo (this_addr, is_add);
 
       increment_v4_address (&this_addr);
     }
@@ -903,7 +923,7 @@ static void *vl_api_nat44_add_del_address_range_t_print
     {
       s = format (s, " - %U ", format_ip4_address, mp->last_ip_address);
     }
-  s = format (s, "twice_nat %d ", mp->twice_nat);
+  s = format (s, "twice_nat %d ", mp->flags & NAT_API_IS_TWICE_NAT);
   FINISH;
 }
 
@@ -926,7 +946,8 @@ send_nat44_address_details (snat_address_t * a,
     }
   else
     rmp->vrf_id = ~0;
-  rmp->twice_nat = twice_nat;
+  if (twice_nat)
+    rmp->flags |= NAT_API_IS_TWICE_NAT;
   rmp->context = context;
 
   vl_api_send_msg (reg, (u8 *) rmp);
@@ -971,13 +992,17 @@ static void
 {
   snat_main_t *sm = &snat_main;
   vl_api_nat44_interface_add_del_feature_reply_t *rmp;
-  u8 is_del = mp->is_add == 0;
   u32 sw_if_index = ntohl (mp->sw_if_index);
+  u8 is_del;
   int rv = 0;
 
+  is_del = !mp->is_add;
+
   VALIDATE_SW_IF_INDEX (mp);
 
-  rv = snat_interface_add_del (sw_if_index, mp->is_inside, is_del);
+  rv =
+    snat_interface_add_del (sw_if_index, mp->flags & NAT_API_IS_INSIDE,
+			    is_del);
 
   BAD_SW_IF_INDEX_LABEL;
 
@@ -992,7 +1017,8 @@ static void *vl_api_nat44_interface_add_del_feature_t_print
   s = format (0, "SCRIPT: nat44_interface_add_del_feature ");
   s = format (s, "sw_if_index %d %s %s",
 	      clib_host_to_net_u32 (mp->sw_if_index),
-	      mp->is_inside ? "in" : "out", mp->is_add ? "" : "del");
+	      mp->flags & NAT_API_IS_INSIDE ? "in" : "out",
+	      mp->is_add ? "" : "del");
 
   FINISH;
 }
@@ -1008,9 +1034,12 @@ send_nat44_interface_details (snat_interface_t * i,
   clib_memset (rmp, 0, sizeof (*rmp));
   rmp->_vl_msg_id = ntohs (VL_API_NAT44_INTERFACE_DETAILS + sm->msg_id_base);
   rmp->sw_if_index = ntohl (i->sw_if_index);
-  rmp->is_inside = (nat_interface_is_inside (i)
-		    && nat_interface_is_outside (i)) ? 2 :
-    nat_interface_is_inside (i);
+
+  if (nat_interface_is_inside (i))
+    rmp->flags |= NAT_API_IS_INSIDE;
+  if (nat_interface_is_outside (i))
+    rmp->flags |= NAT_API_IS_OUTSIDE;
+
   rmp->context = context;
 
   vl_api_send_msg (reg, (u8 *) rmp);
@@ -1052,7 +1081,6 @@ static void
 {
   snat_main_t *sm = &snat_main;
   vl_api_nat44_interface_add_del_output_feature_reply_t *rmp;
-  u8 is_del = mp->is_add == 0;
   u32 sw_if_index = ntohl (mp->sw_if_index);
   int rv = 0;
 
@@ -1064,8 +1092,9 @@ static void
 
   VALIDATE_SW_IF_INDEX (mp);
 
-  rv = snat_interface_add_del_output_feature (sw_if_index, mp->is_inside,
-					      is_del);
+  rv = snat_interface_add_del_output_feature (sw_if_index,
+					      mp->flags & NAT_API_IS_INSIDE,
+					      !mp->is_add);
 
   BAD_SW_IF_INDEX_LABEL;
 send_reply:
@@ -1080,7 +1109,8 @@ static void *vl_api_nat44_interface_add_del_output_feature_t_print
   s = format (0, "SCRIPT: nat44_interface_add_del_output_feature ");
   s = format (s, "sw_if_index %d %s %s",
 	      clib_host_to_net_u32 (mp->sw_if_index),
-	      mp->is_inside ? "in" : "out", mp->is_add ? "" : "del");
+	      mp->flags & NAT_API_IS_INSIDE ? "in" : "out",
+	      mp->is_add ? "" : "del");
 
   FINISH;
 }
@@ -1099,7 +1129,9 @@ send_nat44_interface_output_feature_details (snat_interface_t * i,
     ntohs (VL_API_NAT44_INTERFACE_OUTPUT_FEATURE_DETAILS + sm->msg_id_base);
   rmp->sw_if_index = ntohl (i->sw_if_index);
   rmp->context = context;
-  rmp->is_inside = nat_interface_is_inside (i);
+
+  if (nat_interface_is_inside (i))
+    rmp->flags |= NAT_API_IS_INSIDE;
 
   vl_api_send_msg (reg, (u8 *) rmp);
 }
@@ -1150,6 +1182,7 @@ static void
   int rv = 0;
   snat_protocol_t proto;
   u8 *tag = 0;
+  u32 len = 0;
 
   if (sm->deterministic)
     {
@@ -1159,27 +1192,34 @@ static void
 
   memcpy (&local_addr.as_u8, mp->local_ip_address, 4);
   memcpy (&external_addr.as_u8, mp->external_ip_address, 4);
-  if (mp->addr_only == 0)
+
+  if (!(mp->flags & NAT_API_IS_ADDR_ONLY))
     {
       local_port = clib_net_to_host_u16 (mp->local_port);
       external_port = clib_net_to_host_u16 (mp->external_port);
     }
+
   vrf_id = clib_net_to_host_u32 (mp->vrf_id);
   external_sw_if_index = clib_net_to_host_u32 (mp->external_sw_if_index);
   proto = ip_proto_to_snat_proto (mp->protocol);
-  if (mp->twice_nat)
+
+  if (mp->flags & NAT_API_IS_TWICE_NAT)
     twice_nat = TWICE_NAT;
-  else if (mp->self_twice_nat)
+  else if (mp->flags & NAT_API_IS_SELF_TWICE_NAT)
     twice_nat = TWICE_NAT_SELF;
-  mp->tag[sizeof (mp->tag) - 1] = 0;
-  tag = format (0, "%s", mp->tag);
+
+  len = vl_api_string_len (&mp->tag);
+
+  tag = vec_new (u8, len);
+  memcpy (tag, mp->tag.buf, len);
   vec_terminate_c_string (tag);
 
   rv = snat_add_static_mapping (local_addr, external_addr, local_port,
-				external_port, vrf_id, mp->addr_only,
-				external_sw_if_index, proto, mp->is_add,
-				twice_nat, mp->out2in_only, tag, 0);
-
+				external_port, vrf_id,
+				mp->flags & NAT_API_IS_ADDR_ONLY,
+				external_sw_if_index, proto,
+				mp->is_add, twice_nat,
+				mp->flags & NAT_API_IS_OUT2IN_ONLY, tag, 0);
   vec_free (tag);
 
 send_reply:
@@ -1197,13 +1237,14 @@ static void *vl_api_nat44_add_del_static_mapping_t_print
 	      format_ip4_address, mp->local_ip_address,
 	      format_ip4_address, mp->external_ip_address);
 
-  if (mp->addr_only == 0)
+  if (!(mp->flags & NAT_API_IS_ADDR_ONLY))
     s = format (s, "local_port %d external_port %d ",
 		clib_net_to_host_u16 (mp->local_port),
 		clib_net_to_host_u16 (mp->external_port));
 
   s = format (s, "twice_nat %d out2in_only %d ",
-	      mp->twice_nat, mp->out2in_only);
+	      mp->flags & NAT_API_IS_TWICE_NAT,
+	      mp->flags & NAT_API_IS_OUT2IN_ONLY);
 
   if (mp->vrf_id != ~0)
     s = format (s, "vrf %d", clib_net_to_host_u32 (mp->vrf_id));
@@ -1220,30 +1261,48 @@ send_nat44_static_mapping_details (snat_static_mapping_t * m,
 {
   vl_api_nat44_static_mapping_details_t *rmp;
   snat_main_t *sm = &snat_main;
+  u32 len = sizeof (*rmp);
+
+  if (m->tag)
+    {
+      len += vec_len (m->tag);
+      rmp = vl_msg_api_alloc (len);
+      clib_memset (rmp, 0, len);
+      vl_api_to_api_string (vec_len (m->tag), (char *) m->tag, &rmp->tag);
+    }
+  else
+    {
+      rmp = vl_msg_api_alloc (len);
+      clib_memset (rmp, 0, len);
+    }
 
-  rmp = vl_msg_api_alloc (sizeof (*rmp));
-  clib_memset (rmp, 0, sizeof (*rmp));
   rmp->_vl_msg_id =
     ntohs (VL_API_NAT44_STATIC_MAPPING_DETAILS + sm->msg_id_base);
-  rmp->addr_only = is_addr_only_static_mapping (m);
+
   clib_memcpy (rmp->local_ip_address, &(m->local_addr), 4);
   clib_memcpy (rmp->external_ip_address, &(m->external_addr), 4);
   rmp->external_sw_if_index = ~0;
   rmp->vrf_id = htonl (m->vrf_id);
   rmp->context = context;
+
   if (m->twice_nat == TWICE_NAT)
-    rmp->twice_nat = 1;
+    rmp->flags |= NAT_API_IS_TWICE_NAT;
   else if (m->twice_nat == TWICE_NAT_SELF)
-    rmp->self_twice_nat = 1;
-  rmp->out2in_only = is_out2in_only_static_mapping (m);
-  if (rmp->addr_only == 0)
+    rmp->flags |= NAT_API_IS_SELF_TWICE_NAT;
+
+  if (is_out2in_only_static_mapping (m))
+    rmp->flags |= NAT_API_IS_OUT2IN_ONLY;
+
+  if (is_addr_only_static_mapping (m))
+    {
+      rmp->flags |= NAT_API_IS_ADDR_ONLY;
+    }
+  else
     {
       rmp->protocol = snat_proto_to_ip_proto (m->proto);
       rmp->external_port = htons (m->external_port);
       rmp->local_port = htons (m->local_port);
     }
-  if (m->tag)
-    strncpy ((char *) rmp->tag, (char *) m->tag, vec_len (m->tag));
 
   vl_api_send_msg (reg, (u8 *) rmp);
 }
@@ -1255,25 +1314,41 @@ send_nat44_static_map_resolve_details (snat_static_map_resolve_t * m,
 {
   vl_api_nat44_static_mapping_details_t *rmp;
   snat_main_t *sm = &snat_main;
+  u32 len = sizeof (*rmp);
+
+  if (m->tag)
+    {
+      len += vec_len (m->tag);
+      rmp = vl_msg_api_alloc (len);
+      clib_memset (rmp, 0, len);
+      vl_api_to_api_string (vec_len (m->tag), (char *) m->tag, &rmp->tag);
+    }
+  else
+    {
+      rmp = vl_msg_api_alloc (len);
+      clib_memset (rmp, 0, len);
+    }
 
-  rmp = vl_msg_api_alloc (sizeof (*rmp));
-  clib_memset (rmp, 0, sizeof (*rmp));
   rmp->_vl_msg_id =
     ntohs (VL_API_NAT44_STATIC_MAPPING_DETAILS + sm->msg_id_base);
-  rmp->addr_only = m->addr_only;
   clib_memcpy (rmp->local_ip_address, &(m->l_addr), 4);
   rmp->external_sw_if_index = htonl (m->sw_if_index);
   rmp->vrf_id = htonl (m->vrf_id);
   rmp->context = context;
-  rmp->twice_nat = m->twice_nat;
-  if (m->addr_only == 0)
+
+  if (m->twice_nat)
+    rmp->flags |= NAT_API_IS_TWICE_NAT;
+
+  if (m->addr_only)
+    {
+      rmp->flags |= NAT_API_IS_ADDR_ONLY;
+    }
+  else
     {
       rmp->protocol = snat_proto_to_ip_proto (m->proto);
       rmp->external_port = htons (m->e_port);
       rmp->local_port = htons (m->l_port);
     }
-  if (m->tag)
-    strncpy ((char *) rmp->tag, (char *) m->tag, vec_len (m->tag));
 
   vl_api_send_msg (reg, (u8 *) rmp);
 }
@@ -1334,6 +1409,7 @@ static void
   int rv = 0;
   snat_protocol_t proto = ~0;
   u8 *tag = 0;
+  u32 len = 0;
 
   if (sm->deterministic)
     {
@@ -1341,7 +1417,7 @@ static void
       goto send_reply;
     }
 
-  if (mp->addr_only == 0)
+  if (!(mp->flags & NAT_API_IS_ADDR_ONLY))
     {
       port = clib_net_to_host_u16 (mp->port);
       proto = ip_proto_to_snat_proto (mp->protocol);
@@ -1352,14 +1428,17 @@ static void
     addr.as_u32 = 0;
   else
     memcpy (&addr.as_u8, mp->ip_address, 4);
-  mp->tag[sizeof (mp->tag) - 1] = 0;
-  tag = format (0, "%s", mp->tag);
+
+  len = vl_api_string_len (&mp->tag);
+
+  tag = vec_new (u8, len);
+  memcpy (tag, mp->tag.buf, len);
   vec_terminate_c_string (tag);
 
   rv =
-    snat_add_static_mapping (addr, addr, port, port, vrf_id, mp->addr_only,
-			     sw_if_index, proto, mp->is_add, 0, 0, tag, 1);
-
+    snat_add_static_mapping (addr, addr, port, port, vrf_id,
+			     mp->flags & NAT_API_IS_ADDR_ONLY, sw_if_index,
+			     proto, mp->is_add, 0, 0, tag, 1);
   vec_free (tag);
 
 send_reply:
@@ -1377,7 +1456,7 @@ static void *vl_api_nat44_add_del_identity_mapping_t_print
   else
     s = format (s, "addr %U", format_ip4_address, mp->ip_address);
 
-  if (mp->addr_only == 0)
+  if (!(mp->flags & NAT_API_IS_ADDR_ONLY))
     s =
       format (s, " protocol %d port %d", mp->protocol,
 	      clib_net_to_host_u16 (mp->port));
@@ -1395,20 +1474,33 @@ send_nat44_identity_mapping_details (snat_static_mapping_t * m, int index,
   vl_api_nat44_identity_mapping_details_t *rmp;
   snat_main_t *sm = &snat_main;
   nat44_lb_addr_port_t *local = pool_elt_at_index (m->locals, index);
+  u32 len = sizeof (*rmp);
+
+  if (m->tag)
+    {
+      len += vec_len (m->tag);
+      rmp = vl_msg_api_alloc (len);
+      clib_memset (rmp, 0, len);
+      vl_api_to_api_string (vec_len (m->tag), (char *) m->tag, &rmp->tag);
+    }
+  else
+    {
+      rmp = vl_msg_api_alloc (len);
+      clib_memset (rmp, 0, len);
+    }
 
-  rmp = vl_msg_api_alloc (sizeof (*rmp));
-  clib_memset (rmp, 0, sizeof (*rmp));
   rmp->_vl_msg_id =
     ntohs (VL_API_NAT44_IDENTITY_MAPPING_DETAILS + sm->msg_id_base);
-  rmp->addr_only = is_addr_only_static_mapping (m);
+
+  if (is_addr_only_static_mapping (m))
+    rmp->flags |= NAT_API_IS_ADDR_ONLY;
+
   clib_memcpy (rmp->ip_address, &(m->local_addr), 4);
   rmp->port = htons (m->local_port);
   rmp->sw_if_index = ~0;
   rmp->vrf_id = htonl (local->vrf_id);
   rmp->protocol = snat_proto_to_ip_proto (m->proto);
   rmp->context = context;
-  if (m->tag)
-    strncpy ((char *) rmp->tag, (char *) m->tag, vec_len (m->tag));
 
   vl_api_send_msg (reg, (u8 *) rmp);
 }
@@ -1420,19 +1512,32 @@ send_nat44_identity_map_resolve_details (snat_static_map_resolve_t * m,
 {
   vl_api_nat44_identity_mapping_details_t *rmp;
   snat_main_t *sm = &snat_main;
+  u32 len = sizeof (*rmp);
+
+  if (m->tag)
+    {
+      len += vec_len (m->tag);
+      rmp = vl_msg_api_alloc (len);
+      clib_memset (rmp, 0, len);
+      vl_api_to_api_string (vec_len (m->tag), (char *) m->tag, &rmp->tag);
+    }
+  else
+    {
+      rmp = vl_msg_api_alloc (len);
+      clib_memset (rmp, 0, len);
+    }
 
-  rmp = vl_msg_api_alloc (sizeof (*rmp));
-  clib_memset (rmp, 0, sizeof (*rmp));
   rmp->_vl_msg_id =
     ntohs (VL_API_NAT44_IDENTITY_MAPPING_DETAILS + sm->msg_id_base);
-  rmp->addr_only = m->addr_only;
+
+  if (m->addr_only)
+    rmp->flags = (vl_api_nat_config_flags_t) NAT_API_IS_ADDR_ONLY;
+
   rmp->port = htons (m->l_port);
   rmp->sw_if_index = htonl (m->sw_if_index);
   rmp->vrf_id = htonl (m->vrf_id);
   rmp->protocol = snat_proto_to_ip_proto (m->proto);
   rmp->context = context;
-  if (m->tag)
-    strncpy ((char *) rmp->tag, (char *) m->tag, vec_len (m->tag));
 
   vl_api_send_msg (reg, (u8 *) rmp);
 }
@@ -1491,9 +1596,9 @@ static void
 {
   snat_main_t *sm = &snat_main;
   vl_api_nat44_add_del_interface_addr_reply_t *rmp;
-  u8 is_del = mp->is_add == 0;
   u32 sw_if_index = ntohl (mp->sw_if_index);
   int rv = 0;
+  u8 is_del;
 
   if (sm->deterministic)
     {
@@ -1501,9 +1606,12 @@ static void
       goto send_reply;
     }
 
+  is_del = !mp->is_add;
+
   VALIDATE_SW_IF_INDEX (mp);
 
-  rv = snat_add_interface_address (sm, sw_if_index, is_del, mp->twice_nat);
+  rv = snat_add_interface_address (sm, sw_if_index, is_del,
+				   mp->flags & NAT_API_IS_TWICE_NAT);
 
   BAD_SW_IF_INDEX_LABEL;
 send_reply:
@@ -1518,7 +1626,7 @@ static void *vl_api_nat44_add_del_interface_addr_t_print
   s = format (0, "SCRIPT: nat44_add_del_interface_addr ");
   s = format (s, "sw_if_index %d twice_nat %d %s",
 	      clib_host_to_net_u32 (mp->sw_if_index),
-	      mp->twice_nat, mp->is_add ? "" : "del");
+	      mp->flags & NAT_API_IS_TWICE_NAT, mp->is_add ? "" : "del");
 
   FINISH;
 }
@@ -1536,7 +1644,9 @@ send_nat44_interface_addr_details (u32 sw_if_index,
   rmp->_vl_msg_id =
     ntohs (VL_API_NAT44_INTERFACE_ADDR_DETAILS + sm->msg_id_base);
   rmp->sw_if_index = ntohl (sw_if_index);
-  rmp->twice_nat = twice_nat;
+
+  if (twice_nat)
+    rmp->flags = (vl_api_nat_config_flags_t) NAT_API_IS_TWICE_NAT;
   rmp->context = context;
 
   vl_api_send_msg (reg, (u8 *) rmp);
@@ -1651,10 +1761,16 @@ send_nat44_user_session_details (snat_session_t * s,
     ntohs (VL_API_NAT44_USER_SESSION_DETAILS + sm->msg_id_base);
   clib_memcpy (rmp->outside_ip_address, (&s->out2in.addr), 4);
   clib_memcpy (rmp->inside_ip_address, (&s->in2out.addr), 4);
-  rmp->is_static = snat_is_session_static (s) ? 1 : 0;
-  rmp->is_twicenat = is_twice_nat_session (s) ? 1 : 0;
-  rmp->ext_host_valid = is_ed_session (s)
-    || is_fwd_bypass_session (s) ? 1 : 0;
+
+  if (snat_is_session_static (s))
+    rmp->flags |= NAT_API_IS_STATIC;
+
+  if (is_twice_nat_session (s))
+    rmp->flags |= NAT_API_IS_TWICE_NAT;
+
+  if (is_ed_session (s) || is_fwd_bypass_session (s))
+    rmp->flags |= NAT_API_IS_EXT_HOST_VALID;
+
   rmp->last_heard = clib_host_to_net_u64 ((u64) s->last_heard);
   rmp->total_bytes = clib_host_to_net_u64 (s->total_bytes);
   rmp->total_pkts = ntohl (s->total_pkts);
@@ -1787,7 +1903,9 @@ static void
   nat44_lb_addr_port_t *locals = 0;
   ip4_address_t e_addr;
   snat_protocol_t proto;
+  vl_api_string_t *sp;
   u8 *tag = 0;
+  u32 len = 0;
 
   if (!sm->endpoint_dependent)
     {
@@ -1800,19 +1918,28 @@ static void
 				 clib_net_to_host_u32 (mp->local_num));
   clib_memcpy (&e_addr, mp->external_addr, 4);
   proto = ip_proto_to_snat_proto (mp->protocol);
-  if (mp->twice_nat)
+
+  if (mp->flags & NAT_API_IS_TWICE_NAT)
     twice_nat = TWICE_NAT;
-  else if (mp->self_twice_nat)
+  else if (mp->flags & NAT_API_IS_SELF_TWICE_NAT)
     twice_nat = TWICE_NAT_SELF;
-  mp->tag[sizeof (mp->tag) - 1] = 0;
-  tag = format (0, "%s", mp->tag);
+
+  sp = (void *) &mp->locals +
+    sizeof (vl_api_nat44_lb_addr_port_t) *
+    clib_net_to_host_u32 (mp->local_num);
+
+  len = vl_api_string_len (sp);
+
+  tag = vec_new (u8, len);
+  memcpy (tag, sp->buf, len);
   vec_terminate_c_string (tag);
 
   rv =
     nat44_add_del_lb_static_mapping (e_addr,
 				     clib_net_to_host_u16 (mp->external_port),
-				     proto, locals, mp->is_add, twice_nat,
-				     mp->out2in_only, tag,
+				     proto, locals, mp->is_add,
+				     twice_nat,
+				     mp->flags & NAT_API_IS_OUT2IN_ONLY, tag,
 				     clib_net_to_host_u32 (mp->affinity));
 
   vec_free (locals);
@@ -1829,7 +1956,9 @@ static void *vl_api_nat44_add_del_lb_static_mapping_t_print
 
   s = format (0, "SCRIPT: nat44_add_del_lb_static_mapping ");
   s = format (s, "is_add %d twice_nat %d out2in_only %d ",
-	      mp->is_add, mp->twice_nat, mp->out2in_only);
+	      mp->is_add,
+	      mp->flags & NAT_API_IS_TWICE_NAT,
+	      mp->flags & NAT_API_IS_OUT2IN_ONLY);
 
   FINISH;
 }
@@ -1889,13 +2018,28 @@ send_nat44_lb_static_mapping_details (snat_static_mapping_t * m,
   snat_main_t *sm = &snat_main;
   nat44_lb_addr_port_t *ap;
   vl_api_nat44_lb_addr_port_t *locals;
+  vl_api_string_t *sp;
   u32 local_num = 0;
+  u32 len = sizeof (*rmp);
+
+  if (m->tag)
+    {
+      len += pool_elts (m->locals) *
+	sizeof (nat44_lb_addr_port_t) + vec_len (m->tag);
+      rmp = vl_msg_api_alloc (len);
+      clib_memset (rmp, 0, len);
+
+      sp = (void *) &m->locals +
+	sizeof (vl_api_nat44_lb_addr_port_t) * pool_elts (m->locals);
+      vl_api_to_api_string (vec_len (m->tag), (char *) m->tag, sp);
+    }
+  else
+    {
+      len += pool_elts (m->locals) * sizeof (nat44_lb_addr_port_t);
+      rmp = vl_msg_api_alloc (len);
+      clib_memset (rmp, 0, len);
+    }
 
-  rmp =
-    vl_msg_api_alloc (sizeof (*rmp) +
-		      (pool_elts (m->locals) *
-		       sizeof (nat44_lb_addr_port_t)));
-  clib_memset (rmp, 0, sizeof (*rmp));
   rmp->_vl_msg_id =
     ntohs (VL_API_NAT44_LB_STATIC_MAPPING_DETAILS + sm->msg_id_base);
 
@@ -1903,13 +2047,13 @@ send_nat44_lb_static_mapping_details (snat_static_mapping_t * m,
   rmp->external_port = ntohs (m->external_port);
   rmp->protocol = snat_proto_to_ip_proto (m->proto);
   rmp->context = context;
+
   if (m->twice_nat == TWICE_NAT)
-    rmp->twice_nat = 1;
+    rmp->flags |= NAT_API_IS_TWICE_NAT;
   else if (m->twice_nat == TWICE_NAT_SELF)
-    rmp->self_twice_nat = 1;
-  rmp->out2in_only = is_out2in_only_static_mapping (m);
-  if (m->tag)
-    strncpy ((char *) rmp->tag, (char *) m->tag, vec_len (m->tag));
+    rmp->flags |= NAT_API_IS_SELF_TWICE_NAT;
+  if (is_out2in_only_static_mapping (m))
+    rmp->flags |= NAT_API_IS_OUT2IN_ONLY;
 
   locals = (vl_api_nat44_lb_addr_port_t *) rmp->locals;
   /* *INDENT-OFF* */
@@ -1971,6 +2115,7 @@ vl_api_nat44_del_session_t_handler (vl_api_nat44_del_session_t * mp)
   u16 port, eh_port;
   u32 vrf_id;
   int rv = 0;
+  u8 is_in;
   snat_protocol_t proto;
 
   if (sm->deterministic)
@@ -1986,12 +2131,14 @@ vl_api_nat44_del_session_t_handler (vl_api_nat44_del_session_t * mp)
   memcpy (&eh_addr.as_u8, mp->ext_host_address, 4);
   eh_port = clib_net_to_host_u16 (mp->ext_host_port);
 
-  if (mp->ext_host_valid)
+  is_in = mp->flags & NAT_API_IS_INSIDE;
+
+  if (mp->flags & NAT_API_IS_EXT_HOST_VALID)
     rv =
       nat44_del_ed_session (sm, &addr, port, &eh_addr, eh_port, mp->protocol,
-			    vrf_id, mp->is_in);
+			    vrf_id, is_in);
   else
-    rv = nat44_del_session (sm, &addr, port, proto, vrf_id, mp->is_in);
+    rv = nat44_del_session (sm, &addr, port, proto, vrf_id, is_in);
 
 send_reply:
   REPLY_MACRO (VL_API_NAT44_DEL_SESSION_REPLY);
@@ -2007,8 +2154,9 @@ vl_api_nat44_del_session_t_print (vl_api_nat44_del_session_t * mp,
   s = format (s, "addr %U port %d protocol %d vrf_id %d is_in %d",
 	      format_ip4_address, mp->address,
 	      clib_net_to_host_u16 (mp->port),
-	      mp->protocol, clib_net_to_host_u32 (mp->vrf_id), mp->is_in);
-  if (mp->ext_host_valid)
+	      mp->protocol, clib_net_to_host_u32 (mp->vrf_id),
+	      mp->flags & NAT_API_IS_INSIDE);
+  if (mp->flags & NAT_API_IS_EXT_HOST_VALID)
     s = format (s, "ext_host_address %U ext_host_port %d",
 		format_ip4_address, mp->ext_host_address,
 		clib_net_to_host_u16 (mp->ext_host_port));
@@ -2117,12 +2265,6 @@ vl_api_nat_det_add_del_map_t_handler (vl_api_nat_det_add_del_map_t * mp)
       goto send_reply;
     }
 
-  if (!mp->is_nat44)
-    {
-      rv = VNET_API_ERROR_UNIMPLEMENTED;
-      goto send_reply;
-    }
-
   clib_memcpy (&in_addr, mp->in_addr, 4);
   clib_memcpy (&out_addr, mp->out_addr, 4);
   rv = snat_det_add_map (sm, &in_addr, mp->in_plen, &out_addr,
@@ -2163,13 +2305,6 @@ vl_api_nat_det_forward_t_handler (vl_api_nat_det_forward_t * mp)
       return;
     }
 
-  if (!mp->is_nat44)
-    {
-      out_addr.as_u32 = 0;
-      rv = VNET_API_ERROR_UNIMPLEMENTED;
-      goto send_reply;
-    }
-
   out_addr.as_u32 = 0;
   clib_memcpy (&in_addr, mp->in_addr, 4);
   dm = snat_det_map_by_user (sm, &in_addr);
@@ -2235,8 +2370,6 @@ send_reply:
   /* *INDENT-OFF* */
   REPLY_MACRO2 (VL_API_NAT_DET_REVERSE_REPLY,
   ({
-    rmp->is_nat44 = 1;
-    clib_memset (rmp->in_addr, 0, 16);
     clib_memcpy (rmp->in_addr, &in_addr, 4);
   }))
   /* *INDENT-ON* */
@@ -2264,7 +2397,6 @@ sent_nat_det_map_details (snat_det_map_t * m, vl_api_registration_t * reg,
   rmp = vl_msg_api_alloc (sizeof (*rmp));
   clib_memset (rmp, 0, sizeof (*rmp));
   rmp->_vl_msg_id = ntohs (VL_API_NAT_DET_MAP_DETAILS + sm->msg_id_base);
-  rmp->is_nat44 = 1;
   clib_memcpy (rmp->in_addr, &m->in_addr, 4);
   rmp->in_plen = m->in_plen;
   clib_memcpy (rmp->out_addr, &m->out_addr, 4);
@@ -2383,12 +2515,6 @@ vl_api_nat_det_close_session_in_t_handler (vl_api_nat_det_close_session_in_t *
       goto send_reply;
     }
 
-  if (!mp->is_nat44)
-    {
-      rv = VNET_API_ERROR_UNIMPLEMENTED;
-      goto send_reply;
-    }
-
   clib_memcpy (&in_addr, mp->in_addr, 4);
   clib_memcpy (&ext_addr, mp->ext_addr, 4);
 
@@ -2462,8 +2588,6 @@ vl_api_nat_det_session_dump_t_handler (vl_api_nat_det_session_dump_t * mp)
   reg = vl_api_client_index_to_registration (mp->client_index);
   if (!reg)
     return;
-  if (!mp->is_nat44)
-    return;
 
   clib_memset (&empty_ses, 0, sizeof (empty_ses));
   clib_memcpy (&user_addr, mp->user_addr, 4);
@@ -2619,8 +2743,8 @@ vl_api_nat64_add_del_interface_t_handler (vl_api_nat64_add_del_interface_t *
   VALIDATE_SW_IF_INDEX (mp);
 
   rv =
-    nat64_add_del_interface (ntohl (mp->sw_if_index), mp->is_inside,
-			     mp->is_add);
+    nat64_add_del_interface (ntohl (mp->sw_if_index),
+			     mp->flags & NAT_API_IS_INSIDE, mp->is_add);
 
   BAD_SW_IF_INDEX_LABEL;
 
@@ -2636,7 +2760,8 @@ vl_api_nat64_add_del_interface_t_print (vl_api_nat64_add_del_interface_t * mp,
   s = format (0, "SCRIPT: nat64_add_del_interface ");
   s = format (s, "sw_if_index %d %s %s",
 	      clib_host_to_net_u32 (mp->sw_if_index),
-	      mp->is_inside ? "in" : "out", mp->is_add ? "" : "del");
+	      mp->flags & NAT_API_IS_INSIDE ? "in" : "out",
+	      mp->is_add ? "" : "del");
 
   FINISH;
 }
@@ -2652,9 +2777,12 @@ nat64_api_interface_walk (snat_interface_t * i, void *arg)
   clib_memset (rmp, 0, sizeof (*rmp));
   rmp->_vl_msg_id = ntohs (VL_API_NAT64_INTERFACE_DETAILS + sm->msg_id_base);
   rmp->sw_if_index = ntohl (i->sw_if_index);
-  rmp->is_inside = (nat_interface_is_inside (i)
-		    && nat_interface_is_outside (i)) ? 2 :
-    nat_interface_is_inside (i);
+
+  if (nat_interface_is_inside (i))
+    rmp->flags |= NAT_API_IS_INSIDE;
+  if (nat_interface_is_outside (i))
+    rmp->flags |= NAT_API_IS_OUTSIDE;
+
   rmp->context = ctx->context;
 
   vl_api_send_msg (ctx->reg, (u8 *) rmp);
@@ -2752,7 +2880,8 @@ nat64_api_bib_walk (nat64_db_bib_entry_t * bibe, void *arg)
   rmp->o_port = bibe->out_port;
   rmp->vrf_id = ntohl (fib->ft_table_id);
   rmp->proto = bibe->proto;
-  rmp->is_static = bibe->is_static;
+  if (bibe->is_static)
+    rmp->flags |= NAT_API_IS_STATIC;
   rmp->ses_num = ntohl (bibe->ses_num);
 
   vl_api_send_msg (ctx->reg, (u8 *) rmp);
@@ -2871,10 +3000,10 @@ vl_api_nat64_add_del_prefix_t_handler (vl_api_nat64_add_del_prefix_t * mp)
   ip6_address_t prefix;
   int rv = 0;
 
-  memcpy (&prefix.as_u8, mp->prefix, 16);
+  memcpy (&prefix.as_u8, mp->prefix.prefix, 16);
 
   rv =
-    nat64_add_del_prefix (&prefix, mp->prefix_len,
+    nat64_add_del_prefix (&prefix, mp->prefix.len,
 			  clib_net_to_host_u32 (mp->vrf_id), mp->is_add);
   REPLY_MACRO (VL_API_NAT64_ADD_DEL_PREFIX_REPLY);
 }
@@ -2886,7 +3015,7 @@ vl_api_nat64_add_del_prefix_t_print (vl_api_nat64_add_del_prefix_t * mp,
   u8 *s;
 
   s = format (0, "SCRIPT: nat64_add_del_prefix %U/%u vrf_id %u %s\n",
-	      format_ip6_address, mp->prefix, mp->prefix_len,
+	      format_ip6_address, mp->prefix.prefix, mp->prefix.len,
 	      ntohl (mp->vrf_id), mp->is_add ? "" : "del");
 
   FINISH;
@@ -2902,8 +3031,8 @@ nat64_api_prefix_walk (nat64_prefix_t * p, void *arg)
   rmp = vl_msg_api_alloc (sizeof (*rmp));
   clib_memset (rmp, 0, sizeof (*rmp));
   rmp->_vl_msg_id = ntohs (VL_API_NAT64_PREFIX_DETAILS + sm->msg_id_base);
-  clib_memcpy (rmp->prefix, &(p->prefix), 16);
-  rmp->prefix_len = p->plen;
+  clib_memcpy (rmp->prefix.prefix, &(p->prefix), 16);
+  rmp->prefix.len = p->plen;
   rmp->vrf_id = ntohl (p->vrf_id);
   rmp->context = ctx->context;
 
@@ -3209,8 +3338,8 @@ vl_api_nat66_add_del_interface_t_handler (vl_api_nat66_add_del_interface_t *
   VALIDATE_SW_IF_INDEX (mp);
 
   rv =
-    nat66_interface_add_del (ntohl (mp->sw_if_index), mp->is_inside,
-			     mp->is_add);
+    nat66_interface_add_del (ntohl (mp->sw_if_index),
+			     mp->flags & NAT_API_IS_INSIDE, mp->is_add);
 
   BAD_SW_IF_INDEX_LABEL;
 
@@ -3226,7 +3355,8 @@ vl_api_nat66_add_del_interface_t_print (vl_api_nat66_add_del_interface_t * mp,
   s = format (0, "SCRIPT: nat66_add_del_interface ");
   s = format (s, "sw_if_index %d %s %s",
 	      clib_host_to_net_u32 (mp->sw_if_index),
-	      mp->is_inside ? "in" : "out", mp->is_add ? "" : "del");
+	      mp->flags & NAT_API_IS_INSIDE ? "in" : "out",
+	      mp->is_add ? "" : "del");
 
   FINISH;
 }
@@ -3282,7 +3412,8 @@ nat66_api_interface_walk (snat_interface_t * i, void *arg)
   clib_memset (rmp, 0, sizeof (*rmp));
   rmp->_vl_msg_id = ntohs (VL_API_NAT66_INTERFACE_DETAILS + sm->msg_id_base);
   rmp->sw_if_index = ntohl (i->sw_if_index);
-  rmp->is_inside = nat_interface_is_inside (i);
+  if (nat_interface_is_inside (i))
+    rmp->flags |= NAT_API_IS_INSIDE;
   rmp->context = ctx->context;
 
   vl_api_send_msg (ctx->rp, (u8 *) rmp);
diff --git a/src/plugins/nat/nat_test.c b/src/plugins/nat/nat_test.c
index b1de5340b9d..0371ec48553 100644
--- a/src/plugins/nat/nat_test.c
+++ b/src/plugins/nat/nat_test.c
@@ -221,7 +221,8 @@ static int api_nat44_interface_add_del_feature (vat_main_t * vam)
   M(NAT44_INTERFACE_ADD_DEL_FEATURE, mp);
   mp->sw_if_index = ntohl(sw_if_index);
   mp->is_add = is_add;
-  mp->is_inside = is_inside;
+  if (is_inside)
+    mp->flags |= NAT_API_IS_INSIDE;
 
   S(mp);
   W (ret);
@@ -291,8 +292,11 @@ static int api_nat44_add_del_static_mapping(vat_main_t * vam)
     }
 
   M(NAT44_ADD_DEL_STATIC_MAPPING, mp);
+
   mp->is_add = is_add;
-  mp->addr_only = addr_only;
+  if (addr_only)
+    mp->flags |= NAT_API_IS_ADDR_ONLY;
+
   mp->local_port = ntohs ((u16) local_port);
   mp->external_port = ntohs ((u16) external_port);
   mp->external_sw_if_index = ntohl (sw_if_index);
@@ -327,20 +331,21 @@ static void vl_api_nat44_static_mapping_details_t_handler
 {
   snat_test_main_t * sm = &snat_test_main;
   vat_main_t *vam = sm->vat_main;
+  nat_config_flags_t flags = (nat_config_flags_t) mp->flags;
 
-  if (mp->addr_only && mp->external_sw_if_index != ~0)
+  if (flags & NAT_API_IS_ADDR_ONLY && mp->external_sw_if_index != ~0)
       fformat (vam->ofp, "%15U%6s%15d%6s%11d%6d\n",
                format_ip4_address, &mp->local_ip_address, "",
                ntohl (mp->external_sw_if_index), "",
                ntohl (mp->vrf_id),
                mp->protocol);
-  else if (mp->addr_only && mp->external_sw_if_index == ~0)
+  else if (flags & NAT_API_IS_ADDR_ONLY && mp->external_sw_if_index == ~0)
       fformat (vam->ofp, "%15U%6s%15U%6s%11d%6d\n",
                format_ip4_address, &mp->local_ip_address, "",
                format_ip4_address, &mp->external_ip_address, "",
                ntohl (mp->vrf_id),
                mp->protocol);
-  else if (!mp->addr_only && mp->external_sw_if_index != ~0)
+  else if (!(flags & NAT_API_IS_ADDR_ONLY) && mp->external_sw_if_index != ~0)
       fformat (vam->ofp, "%15U%6d%15d%6d%11d%6d\n",
                format_ip4_address, &mp->local_ip_address,
                ntohs (mp->local_port),
@@ -469,11 +474,19 @@ static int api_nat44_address_dump(vat_main_t * vam)
 static void vl_api_nat44_interface_details_t_handler
   (vl_api_nat44_interface_details_t *mp)
 {
+  nat_config_flags_t flags = (nat_config_flags_t) mp->flags;
   snat_test_main_t * sm = &snat_test_main;
   vat_main_t *vam = sm->vat_main;
 
-  fformat (vam->ofp, "sw_if_index %d %s\n", ntohl (mp->sw_if_index),
-           mp->is_inside ? "in" : "out");
+  if ((flags & NAT_API_IS_INSIDE) && (flags & NAT_API_IS_OUTSIDE))
+    {
+      fformat (vam->ofp, "sw_if_index %d in & out\n", ntohl (mp->sw_if_index));
+    }
+  else
+    {
+      fformat (vam->ofp, "sw_if_index %d %s\n", ntohl (mp->sw_if_index),
+               flags & NAT_API_IS_INSIDE ? "in" : "out");
+    }
 }
 
 static int api_nat44_interface_dump(vat_main_t * vam)
@@ -590,6 +603,7 @@ static int api_nat44_add_del_interface_addr (vat_main_t * vam)
 
   M(NAT44_ADD_DEL_INTERFACE_ADDR, mp);
   mp->sw_if_index = ntohl(sw_if_index);
+
   mp->is_add = is_add;
 
   S(mp);
@@ -671,7 +685,7 @@ static void vl_api_nat44_user_session_details_t_handler
 
   fformat(vam->ofp, "%s session %U:%d to %U:%d protocol id %d "
                     "total packets %d total bytes %lld\n",
-          mp->is_static ? "static" : "dynamic",
+          mp->flags & NAT_API_IS_STATIC ? "static" : "dynamic",
           format_ip4_address, mp->inside_ip_address, ntohs(mp->inside_port),
           format_ip4_address, mp->outside_ip_address, ntohs(mp->outside_port),
           ntohs(mp->protocol), ntohl(mp->total_pkts),