Port restricted NAT44 (VPP-1048)

For the MAP-E CE limit port choice based on PSID
CLI: nat44 addr-port-assignment-alg map-e psid <n> psid-offset <n> psid-len <n>

Change-Id: Iecceee61fca372cb5790c16993a82fbdc9930f0f
Signed-off-by: Matus Fabian <matfabia@cisco.com>

3 files changed, 181 insertions, 8 deletions

diff --git a/src/plugins/nat/nat.c b/src/plugins/nat/nat.c
index 7e651e5e9e5..8c188f65709 100644
--- a/src/plugins/nat/nat.c
+++ b/src/plugins/nat/nat.c
@@ -1378,6 +1378,16 @@ snat_ip4_add_del_interface_address_cb (ip4_main_t * im,
                                        u32 if_address_index,
                                        u32 is_delete);
 
+static int
+nat_alloc_addr_and_port_default (snat_address_t * addresses,
+                                 u32 fib_index,
+                                 u32 thread_index,
+                                 snat_session_key_t * k,
+                                 u32 * address_indexp,
+                                 u8 vrf_mode,
+                                 u16 port_per_thread,
+                                 u32 snat_thread_index);
+
 static clib_error_t * snat_init (vlib_main_t * vm)
 {
   snat_main_t * sm = &snat_main;
@@ -1408,6 +1418,7 @@ static clib_error_t * snat_init (vlib_main_t * vm)
   sm->tcp_established_timeout = SNAT_TCP_ESTABLISHED_TIMEOUT;
   sm->tcp_transitory_timeout = SNAT_TCP_TRANSITORY_TIMEOUT;
   sm->icmp_timeout = SNAT_ICMP_TIMEOUT;
+  sm->alloc_addr_and_port = nat_alloc_addr_and_port_default;
 
   p = hash_get_mem (tm->thread_registrations_by_name, "workers");
   if (p)
@@ -1587,14 +1598,32 @@ snat_random_port (u16 min, u16 max)
     (random_u32_max() / (max - min + 1) + 1);
 }
 
-int snat_alloc_outside_address_and_port (snat_address_t * addresses,
-                                         u32 fib_index,
-                                         u32 thread_index,
-                                         snat_session_key_t * k,
-                                         u32 * address_indexp,
-                                         u8 vrf_mode,
-                                         u16 port_per_thread,
-                                         u32 snat_thread_index)
+int
+snat_alloc_outside_address_and_port (snat_address_t * addresses,
+                                     u32 fib_index,
+                                     u32 thread_index,
+                                     snat_session_key_t * k,
+                                     u32 * address_indexp,
+                                     u8 vrf_mode,
+                                     u16 port_per_thread,
+                                     u32 snat_thread_index)
+{
+  snat_main_t *sm = &snat_main;
+
+  return sm->alloc_addr_and_port(addresses, fib_index, thread_index, k,
+                                 address_indexp, vrf_mode, port_per_thread,
+                                 snat_thread_index);
+}
+
+static int
+nat_alloc_addr_and_port_default (snat_address_t * addresses,
+                                 u32 fib_index,
+                                 u32 thread_index,
+                                 snat_session_key_t * k,
+                                 u32 * address_indexp,
+                                 u8 vrf_mode,
+                                 u16 port_per_thread,
+                                 u32 snat_thread_index)
 {
   int i;
   snat_address_t *a;
@@ -1641,6 +1670,59 @@ int snat_alloc_outside_address_and_port (snat_address_t * addresses,
   return 1;
 }
 
+static int
+nat_alloc_addr_and_port_mape (snat_address_t * addresses,
+                              u32 fib_index,
+                              u32 thread_index,
+                              snat_session_key_t * k,
+                              u32 * address_indexp,
+                              u8 vrf_mode,
+                              u16 port_per_thread,
+                              u32 snat_thread_index)
+{
+  snat_main_t *sm = &snat_main;
+  snat_address_t *a = addresses;
+  u16 m, ports, portnum, A, j;
+  m = 16 - (sm->psid_offset + sm->psid_length);
+  ports = (1 << (16 - sm->psid_length)) - (1 << m);
+
+  if (!vec_len (addresses))
+    goto exhausted;
+
+  switch (k->protocol)
+    {
+#define _(N, i, n, s) \
+    case SNAT_PROTOCOL_##N: \
+      if (a->busy_##n##_ports < ports) \
+        { \
+          while (1) \
+            { \
+              A = snat_random_port(1, pow2_mask(sm->psid_offset)); \
+              j = snat_random_port(0, pow2_mask(m)); \
+              portnum = A | (sm->psid << sm->psid_offset) | (j << (16 - m)); \
+              if (clib_bitmap_get_no_check (a->busy_##n##_port_bitmap, portnum)) \
+                continue; \
+              clib_bitmap_set_no_check (a->busy_##n##_port_bitmap, portnum, 1); \
+              a->busy_##n##_ports++; \
+              k->addr = a->addr; \
+              k->port = clib_host_to_net_u16 (portnum); \
+              *address_indexp = i; \
+              return 0; \
+            } \
+        } \
+      break;
+      foreach_snat_protocol
+#undef _
+    default:
+      clib_warning("unknown protocol");
+      return 1;
+    }
+
+exhausted:
+  /* Totally out of translations to use... */
+  snat_ipfix_logging_addresses_exhausted(0);
+  return 1;
+}
 
 static clib_error_t *
 add_address_command_fn (vlib_main_t * vm,
@@ -3202,6 +3284,52 @@ VLIB_CLI_COMMAND (nat44_del_session_command, static) = {
 };
 
 static clib_error_t *
+nat44_set_alloc_addr_and_port_alg_command_fn (vlib_main_t * vm,
+                                              unformat_input_t * input,
+                                              vlib_cli_command_t * cmd)
+{
+  snat_main_t *sm = &snat_main;
+  unformat_input_t _line_input, *line_input = &_line_input;
+  clib_error_t *error = 0;
+  u32 psid, psid_offset, psid_length;
+
+  /* Get a line of input. */
+  if (!unformat_user (input, unformat_line_input, line_input))
+    return 0;
+
+  while (unformat_check_input (line_input) != UNFORMAT_END_OF_INPUT)
+    {
+      if (unformat (line_input, "default"))
+        sm->alloc_addr_and_port = nat_alloc_addr_and_port_default;
+      else if (unformat (line_input, "map-e psid %d psid-offset %d psid-len %d",
+               &psid, &psid_offset, &psid_length))
+        {
+          sm->alloc_addr_and_port = nat_alloc_addr_and_port_mape;
+          sm->psid = (u16) psid;
+          sm->psid_offset = (u16) psid_offset;
+          sm->psid_length = (u16) psid_length;
+        }
+      else
+        {
+          error = clib_error_return (0, "unknown input '%U'",
+				     format_unformat_error, line_input);
+          goto done;
+        }
+    }
+
+done:
+  unformat_free (line_input);
+
+  return error;
+};
+
+VLIB_CLI_COMMAND (nat44_set_alloc_addr_and_port_alg_command, static) = {
+    .path = "nat44 addr-port-assignment-alg",
+    .short_help = "nat44 addr-port-assignment-alg <alg-name> [<alg-params>]",
+    .function = nat44_set_alloc_addr_and_port_alg_command_fn,
+};
+
+static clib_error_t *
 snat_det_map_command_fn (vlib_main_t * vm,
                          unformat_input_t * input,
                          vlib_cli_command_t * cmd)
diff --git a/src/plugins/nat/nat.h b/src/plugins/nat/nat.h
index 5bd0a119f38..8178d76a4ac 100644
--- a/src/plugins/nat/nat.h
+++ b/src/plugins/nat/nat.h
@@ -269,6 +269,15 @@ typedef u32 snat_icmp_match_function_t (struct snat_main_s *sm,
 
 typedef u32 (snat_get_worker_function_t) (ip4_header_t * ip, u32 rx_fib_index);
 
+typedef int nat_alloc_out_addr_and_port_function_t (snat_address_t * addresses,
+                                                    u32 fib_index,
+                                                    u32 thread_index,
+                                                    snat_session_key_t * k,
+                                                    u32 * address_indexp,
+                                                    u8 vrf_mode,
+                                                    u16 port_per_thread,
+                                                    u32 snat_thread_index);
+
 typedef struct snat_main_s {
   /* Endpoint address dependent sessions lookup tables */
   clib_bihash_16_8_t out2in_ed;
@@ -304,6 +313,10 @@ typedef struct snat_main_s {
 
   /* Vector of outside addresses */
   snat_address_t * addresses;
+  nat_alloc_out_addr_and_port_function_t *alloc_addr_and_port;
+  u8 psid_offset;
+  u8 psid_length;
+  u16 psid;
 
   /* sw_if_indices whose intfc addresses should be auto-added */
   u32 * auto_add_sw_if_indices;
diff --git a/test/test_nat.py b/test/test_nat.py
index 76c52828ad9..b01fe076754 100644
--- a/test/test_nat.py
+++ b/test/test_nat.py
@@ -2756,11 +2756,43 @@ class TestNAT44(MethodHolder):
         self.assertEqual(p[TCP].dport, self.tcp_port_in)
         self.assertEqual(data, p[Raw].load)
 
+    def test_port_restricted(self):
+        """ Port restricted NAT44 (MAP-E CE) """
+        self.nat44_add_address(self.nat_addr)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
+        self.vapi.cli("nat44 addr-port-assignment-alg map-e psid 10 "
+                      "psid-offset 6 psid-len 6")
+
+        p = (Ether(src=self.pg0.remote_mac, dst=self.pg0.local_mac) /
+             IP(src=self.pg0.remote_ip4, dst=self.pg1.remote_ip4) /
+             TCP(sport=4567, dport=22))
+        self.pg0.add_stream(p)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        capture = self.pg1.get_capture(1)
+        p = capture[0]
+        try:
+            ip = p[IP]
+            tcp = p[TCP]
+            self.assertEqual(ip.dst, self.pg1.remote_ip4)
+            self.assertEqual(ip.src, self.nat_addr)
+            self.assertEqual(tcp.dport, 22)
+            self.assertNotEqual(tcp.sport, 4567)
+            self.assertEqual((tcp.sport >> 6) & 63, 10)
+            self.check_tcp_checksum(p)
+            self.check_ip_checksum(p)
+        except:
+            self.logger.error(ppp("Unexpected or invalid packet:", p))
+            raise
+
     def tearDown(self):
         super(TestNAT44, self).tearDown()
         if not self.vpp_dead:
             self.logger.info(self.vapi.cli("show nat44 verbose"))
             self.logger.info(self.vapi.cli("show nat virtual-reassembly"))
+            self.vapi.cli("nat44 addr-port-assignment-alg default")
             self.clear_nat44()