NAT44 virtual fragmentation reassembly for endpoint-dependent mode (VPP-1325)

Change-Id: I36ece2ef2eaef9fa559d69ec7f7f07e7c16a7a9d
Signed-off-by: Juraj Sloboda <jsloboda@cisco.com>

1 files changed, 389 insertions, 16 deletions

diff --git a/src/plugins/nat/out2in.c b/src/plugins/nat/out2in.c
index 3d4e9228e67..ba343ad72a5 100755
--- a/src/plugins/nat/out2in.c
+++ b/src/plugins/nat/out2in.c
@@ -106,6 +106,7 @@ vlib_node_registration_t snat_det_out2in_node;
 vlib_node_registration_t nat44_out2in_reass_node;
 vlib_node_registration_t nat44_ed_out2in_node;
 vlib_node_registration_t nat44_ed_out2in_slowpath_node;
+vlib_node_registration_t nat44_ed_out2in_reass_node;
 
 #define foreach_snat_out2in_error                       \
 _(UNSUPPORTED_PROTOCOL, "Unsupported protocol")         \
@@ -539,13 +540,16 @@ static inline u32 icmp_out2in (snat_main_t *sm,
   if (next0 == SNAT_OUT2IN_NEXT_DROP || dont_translate)
     goto out;
 
-  sum0 = ip_incremental_checksum (0, icmp0,
-                                  ntohs(ip0->length) - ip4_header_bytes (ip0));
-  checksum0 = ~ip_csum_fold (sum0);
-  if (checksum0 != 0 && checksum0 != 0xffff)
+  if (PREDICT_TRUE (!ip4_is_fragment (ip0)))
     {
-      next0 = SNAT_OUT2IN_NEXT_DROP;
-      goto out;
+      sum0 = ip_incremental_checksum (0, icmp0,
+                                      ntohs(ip0->length) - ip4_header_bytes (ip0));
+      checksum0 = ~ip_csum_fold (sum0);
+      if (checksum0 != 0 && checksum0 != 0xffff)
+        {
+          next0 = SNAT_OUT2IN_NEXT_DROP;
+          goto out;
+        }
     }
 
   old_addr0 = ip0->dst_address.as_u32;
@@ -1582,6 +1586,7 @@ typedef enum {
   NAT44_ED_OUT2IN_NEXT_ICMP_ERROR,
   NAT44_ED_OUT2IN_NEXT_IN2OUT,
   NAT44_ED_OUT2IN_NEXT_SLOW_PATH,
+  NAT44_ED_OUT2IN_NEXT_REASS,
   NAT44_ED_OUT2IN_N_NEXT,
 } nat44_ed_out2in_next_t;
 
@@ -2298,7 +2303,7 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
             }
           else
             {
-              if (PREDICT_FALSE (proto0 == ~0 || proto0 == SNAT_PROTOCOL_ICMP))
+              if (PREDICT_FALSE (proto0 == ~0))
                 {
                   next0 = NAT44_ED_OUT2IN_NEXT_SLOW_PATH;
                   goto trace00;
@@ -2306,8 +2311,13 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
 
               if (ip4_is_fragment (ip0))
                 {
-                  b0->error = node->errors[SNAT_OUT2IN_ERROR_DROP_FRAGMENT];
-                  next0 = NAT44_ED_OUT2IN_NEXT_DROP;
+                  next0 = NAT44_ED_OUT2IN_NEXT_REASS;
+                  goto trace00;
+                }
+
+              if (PREDICT_FALSE (proto0 == SNAT_PROTOCOL_ICMP))
+                {
+                  next0 = NAT44_ED_OUT2IN_NEXT_SLOW_PATH;
                   goto trace00;
                 }
             }
@@ -2501,7 +2511,7 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
             }
           else
             {
-              if (PREDICT_FALSE (proto1 == ~0 || proto1 == SNAT_PROTOCOL_ICMP))
+              if (PREDICT_FALSE (proto1 == ~0))
                 {
                   next1 = NAT44_ED_OUT2IN_NEXT_SLOW_PATH;
                   goto trace01;
@@ -2509,8 +2519,13 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
 
               if (ip4_is_fragment (ip1))
                 {
-                  b1->error = node->errors[SNAT_OUT2IN_ERROR_DROP_FRAGMENT];
-                  next1 = NAT44_ED_OUT2IN_NEXT_DROP;
+                  next1 = NAT44_ED_OUT2IN_NEXT_REASS;
+                  goto trace01;
+                }
+
+              if (PREDICT_FALSE (proto1 == SNAT_PROTOCOL_ICMP))
+                {
+                  next1 = NAT44_ED_OUT2IN_NEXT_SLOW_PATH;
                   goto trace01;
                 }
             }
@@ -2736,7 +2751,7 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
             }
           else
             {
-              if (PREDICT_FALSE (proto0 == ~0 || proto0 == SNAT_PROTOCOL_ICMP))
+              if (PREDICT_FALSE (proto0 == ~0))
                 {
                   next0 = NAT44_ED_OUT2IN_NEXT_SLOW_PATH;
                   goto trace0;
@@ -2744,8 +2759,13 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
 
               if (ip4_is_fragment (ip0))
                 {
-                  b0->error = node->errors[SNAT_OUT2IN_ERROR_DROP_FRAGMENT];
-                  next0 = NAT44_ED_OUT2IN_NEXT_DROP;
+                  next0 = NAT44_ED_OUT2IN_NEXT_REASS;
+                  goto trace0;
+                }
+
+              if (PREDICT_FALSE (proto0 == SNAT_PROTOCOL_ICMP))
+                {
+                  next0 = NAT44_ED_OUT2IN_NEXT_SLOW_PATH;
                   goto trace0;
                 }
             }
@@ -2891,7 +2911,6 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
             }
 
           pkts_processed += next0 != NAT44_ED_OUT2IN_NEXT_DROP;
-
           /* verify speculative enqueue, maybe switch current next frame */
 	  vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
 					   to_next, n_left_to_next,
@@ -2936,6 +2955,7 @@ VLIB_REGISTER_NODE (nat44_ed_out2in_node) = {
     [NAT44_ED_OUT2IN_NEXT_SLOW_PATH] = "nat44-ed-out2in-slowpath",
     [NAT44_ED_OUT2IN_NEXT_ICMP_ERROR] = "ip4-icmp-error",
     [NAT44_ED_OUT2IN_NEXT_IN2OUT] = "nat44-ed-in2out",
+    [NAT44_ED_OUT2IN_NEXT_REASS] = "nat44-ed-out2in-reass",
   },
 };
 
@@ -2970,12 +2990,365 @@ VLIB_REGISTER_NODE (nat44_ed_out2in_slowpath_node) = {
     [NAT44_ED_OUT2IN_NEXT_SLOW_PATH] = "nat44-ed-out2in-slowpath",
     [NAT44_ED_OUT2IN_NEXT_ICMP_ERROR] = "ip4-icmp-error",
     [NAT44_ED_OUT2IN_NEXT_IN2OUT] = "nat44-ed-in2out",
+    [NAT44_ED_OUT2IN_NEXT_REASS] = "nat44-ed-out2in-reass",
   },
 };
 
 VLIB_NODE_FUNCTION_MULTIARCH (nat44_ed_out2in_slowpath_node,
                               nat44_ed_out2in_slow_path_fn);
 
+static uword
+nat44_ed_out2in_reass_node_fn (vlib_main_t * vm,
+                               vlib_node_runtime_t * node,
+                               vlib_frame_t * frame)
+{
+  u32 n_left_from, *from, *to_next;
+  snat_out2in_next_t next_index;
+  u32 pkts_processed = 0;
+  snat_main_t *sm = &snat_main;
+  f64 now = vlib_time_now (vm);
+  u32 thread_index = vm->thread_index;
+  snat_main_per_thread_data_t *per_thread_data =
+    &sm->per_thread_data[thread_index];
+  u32 *fragments_to_drop = 0;
+  u32 *fragments_to_loopback = 0;
+
+  from = vlib_frame_vector_args (frame);
+  n_left_from = frame->n_vectors;
+  next_index = node->cached_next_index;
+
+  while (n_left_from > 0)
+    {
+      u32 n_left_to_next;
+
+      vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);
+
+      while (n_left_from > 0 && n_left_to_next > 0)
+       {
+          u32 bi0, sw_if_index0, proto0, rx_fib_index0, new_addr0, old_addr0;
+	  vlib_buffer_t *b0;
+          u32 next0;
+          u8 cached0 = 0;
+          ip4_header_t *ip0;
+          nat_reass_ip4_t *reass0;
+          udp_header_t * udp0;
+          tcp_header_t * tcp0;
+          icmp46_header_t * icmp0;
+          clib_bihash_kv_16_8_t kv0, value0;
+          snat_session_t * s0 = 0;
+          u16 old_port0, new_port0;
+          ip_csum_t sum0;
+          snat_session_key_t e_key0, l_key0;
+          lb_nat_type_t lb0;
+          twice_nat_type_t twice_nat0;
+
+          /* speculatively enqueue b0 to the current next frame */
+	  bi0 = from[0];
+	  to_next[0] = bi0;
+	  from += 1;
+	  to_next += 1;
+	  n_left_from -= 1;
+	  n_left_to_next -= 1;
+
+	  b0 = vlib_get_buffer (vm, bi0);
+          next0 = NAT44_ED_OUT2IN_NEXT_LOOKUP;
+
+          sw_if_index0 = vnet_buffer(b0)->sw_if_index[VLIB_RX];
+          rx_fib_index0 = fib_table_get_index_for_sw_if_index (FIB_PROTOCOL_IP4,
+                                                               sw_if_index0);
+
+          if (PREDICT_FALSE (nat_reass_is_drop_frag(0)))
+            {
+              next0 = NAT44_ED_OUT2IN_NEXT_DROP;
+              b0->error = node->errors[SNAT_OUT2IN_ERROR_DROP_FRAGMENT];
+              goto trace0;
+            }
+
+          ip0 = (ip4_header_t *) vlib_buffer_get_current (b0);
+          udp0 = ip4_next_header (ip0);
+          tcp0 = (tcp_header_t *) udp0;
+          icmp0 = (icmp46_header_t *) udp0;
+          proto0 = ip_proto_to_snat_proto (ip0->protocol);
+
+          reass0 = nat_ip4_reass_find_or_create (ip0->src_address,
+                                                 ip0->dst_address,
+                                                 ip0->fragment_id,
+                                                 ip0->protocol,
+                                                 1,
+                                                 &fragments_to_drop);
+
+          if (PREDICT_FALSE (!reass0))
+            {
+              next0 = NAT44_ED_OUT2IN_NEXT_DROP;
+              b0->error = node->errors[SNAT_OUT2IN_ERROR_MAX_REASS];
+              nat_log_notice ("maximum reassemblies exceeded");
+              goto trace0;
+            }
+
+          if (PREDICT_FALSE (ip4_is_first_fragment (ip0)))
+            {
+              if (PREDICT_FALSE (proto0 == SNAT_PROTOCOL_ICMP))
+                {
+                  next0 = icmp_out2in_slow_path
+                      (sm, b0, ip0, icmp0, sw_if_index0, rx_fib_index0, node,
+                       next0, now, thread_index, &s0);
+
+                  if (PREDICT_TRUE(next0 != NAT44_ED_OUT2IN_NEXT_DROP))
+                    {
+                      if (s0)
+                        reass0->sess_index = s0 - per_thread_data->sessions;
+                      else
+                        reass0->flags |= NAT_REASS_FLAG_ED_DONT_TRANSLATE;
+                      reass0->thread_index = thread_index;
+                      nat_ip4_reass_get_frags (reass0, &fragments_to_loopback);
+                    }
+
+	          goto trace0;
+	        }
+
+              make_ed_kv (&kv0, &ip0->dst_address, &ip0->src_address, ip0->protocol,
+		          rx_fib_index0, udp0->dst_port, udp0->src_port);
+
+              if (clib_bihash_search_16_8 (&per_thread_data->out2in_ed, &kv0, &value0))
+                {
+                  /* Try to match static mapping by external address and port,
+                     destination address and port in packet */
+                  e_key0.addr = ip0->dst_address;
+                  e_key0.port = udp0->dst_port;
+                  e_key0.protocol = proto0;
+                  e_key0.fib_index = rx_fib_index0;
+                  if (snat_static_mapping_match(sm, e_key0, &l_key0, 1, 0,
+                      &twice_nat0, &lb0, 0))
+                    {
+                      /*
+                       * Send DHCP packets to the ipv4 stack, or we won't
+                       * be able to use dhcp client on the outside interface
+                       */
+                      if (PREDICT_FALSE (proto0 == SNAT_PROTOCOL_UDP
+                          && (udp0->dst_port
+                              == clib_host_to_net_u16(UDP_DST_PORT_dhcp_to_client))))
+			{
+                          vnet_feature_next(&next0, b0);
+                          goto trace0;
+                        }
+
+                      if (!sm->forwarding_enabled)
+                        {
+                          b0->error = node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
+                          next0 = NAT44_ED_OUT2IN_NEXT_DROP;
+                        }
+                      else
+		        {
+			  if (next_src_nat(sm, ip0, ip0->protocol,
+			                   udp0->src_port, udp0->dst_port,
+					   thread_index, rx_fib_index0))
+			    {
+			      next0 = NAT44_ED_OUT2IN_NEXT_IN2OUT;
+			      goto trace0;
+			    }
+			  create_bypass_for_fwd(sm, ip0, rx_fib_index0,
+			                        thread_index);
+			  reass0->flags |= NAT_REASS_FLAG_ED_DONT_TRANSLATE;
+			  nat_ip4_reass_get_frags (reass0, &fragments_to_loopback);
+		        }
+                      goto trace0;
+                    }
+
+                  /* Create session initiated by host from external network */
+                  s0 = create_session_for_static_mapping_ed(sm, b0, l_key0,
+                                                            e_key0, node,
+                                                            thread_index,
+                                                            twice_nat0, lb0,
+							    now);
+                  if (!s0)
+                    {
+                      b0->error = node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
+                      next0 = NAT44_ED_OUT2IN_NEXT_DROP;
+                      goto trace0;
+                    }
+                  reass0->sess_index = s0 - per_thread_data->sessions;
+                  reass0->thread_index = thread_index;
+                }
+              else
+                {
+                  s0 = pool_elt_at_index (per_thread_data->sessions,
+                                          value0.value);
+                  reass0->sess_index = value0.value;
+                }
+              nat_ip4_reass_get_frags (reass0, &fragments_to_loopback);
+            }
+          else
+            {
+              if (reass0->flags & NAT_REASS_FLAG_ED_DONT_TRANSLATE)
+                goto trace0;
+              if (PREDICT_FALSE (reass0->sess_index == (u32) ~0))
+                {
+                  if (nat_ip4_reass_add_fragment (reass0, bi0, &fragments_to_drop))
+                    {
+                      b0->error = node->errors[SNAT_OUT2IN_ERROR_MAX_FRAG];
+                      nat_log_notice ("maximum fragments per reassembly exceeded");
+                      next0 = NAT44_ED_OUT2IN_NEXT_DROP;
+                      goto trace0;
+                    }
+                  cached0 = 1;
+                  goto trace0;
+                }
+              s0 = pool_elt_at_index (per_thread_data->sessions,
+                                      reass0->sess_index);
+            }
+
+          old_addr0 = ip0->dst_address.as_u32;
+          ip0->dst_address = s0->in2out.addr;
+          new_addr0 = ip0->dst_address.as_u32;
+          vnet_buffer(b0)->sw_if_index[VLIB_TX] = s0->in2out.fib_index;
+
+          sum0 = ip0->checksum;
+          sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
+                                 ip4_header_t,
+                                 dst_address /* changed member */);
+          if (PREDICT_FALSE (is_twice_nat_session (s0)))
+            sum0 = ip_csum_update (sum0, ip0->src_address.as_u32,
+                                   s0->ext_host_nat_addr.as_u32, ip4_header_t,
+                                   src_address);
+          ip0->checksum = ip_csum_fold (sum0);
+
+          if (PREDICT_FALSE (ip4_is_first_fragment (ip0)))
+            {
+              if (PREDICT_TRUE(proto0 == SNAT_PROTOCOL_TCP))
+                {
+                  old_port0 = tcp0->dst_port;
+                  tcp0->dst_port = s0->in2out.port;
+                  new_port0 = tcp0->dst_port;
+
+                  sum0 = tcp0->checksum;
+                  sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
+                                         ip4_header_t,
+                                         dst_address /* changed member */);
+
+                  sum0 = ip_csum_update (sum0, old_port0, new_port0,
+                                         ip4_header_t /* cheat */,
+                                         length /* changed member */);
+                  if (is_twice_nat_session (s0))
+                    {
+                      sum0 = ip_csum_update (sum0, ip0->src_address.as_u32,
+                                             s0->ext_host_nat_addr.as_u32,
+                                             ip4_header_t, dst_address);
+                      sum0 = ip_csum_update (sum0, tcp0->src_port,
+                                             s0->ext_host_nat_port, ip4_header_t,
+                                             length);
+                      tcp0->src_port = s0->ext_host_nat_port;
+                      ip0->src_address.as_u32 = s0->ext_host_nat_addr.as_u32;
+                    }
+                  tcp0->checksum = ip_csum_fold(sum0);
+                }
+              else
+                {
+                  old_port0 = udp0->dst_port;
+                  udp0->dst_port = s0->in2out.port;
+                  if (is_twice_nat_session (s0))
+                    {
+                      udp0->src_port = s0->ext_host_nat_port;
+                      ip0->src_address.as_u32 = s0->ext_host_nat_addr.as_u32;
+                    }
+                  udp0->checksum = 0;
+                }
+            }
+
+          /* Accounting */
+          nat44_session_update_counters (s0, now,
+                                         vlib_buffer_length_in_chain (vm, b0));
+          /* Per-user LRU list maintenance */
+          nat44_session_update_lru (sm, s0, thread_index);
+
+        trace0:
+          if (PREDICT_FALSE((node->flags & VLIB_NODE_FLAG_TRACE)
+                            && (b0->flags & VLIB_BUFFER_IS_TRACED)))
+            {
+              nat44_out2in_reass_trace_t *t =
+                 vlib_add_trace (vm, node, b0, sizeof (*t));
+              t->cached = cached0;
+              t->sw_if_index = sw_if_index0;
+              t->next_index = next0;
+            }
+
+          if (cached0)
+            {
+              n_left_to_next++;
+              to_next--;
+            }
+          else
+            {
+              pkts_processed += next0 != NAT44_ED_OUT2IN_NEXT_DROP;
+
+              /* verify speculative enqueue, maybe switch current next frame */
+              vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
+                                               to_next, n_left_to_next,
+                                               bi0, next0);
+            }
+
+	  if (n_left_from == 0 && vec_len (fragments_to_loopback))
+	    {
+	      from = vlib_frame_vector_args (frame);
+	      u32 len = vec_len (fragments_to_loopback);
+	      if (len <= VLIB_FRAME_SIZE)
+		{
+		  clib_memcpy (from, fragments_to_loopback, sizeof (u32) * len);
+		  n_left_from = len;
+		  vec_reset_length (fragments_to_loopback);
+		}
+	      else
+		{
+		  clib_memcpy (from,
+                               fragments_to_loopback + (len - VLIB_FRAME_SIZE),
+                               sizeof (u32) * VLIB_FRAME_SIZE);
+		  n_left_from = VLIB_FRAME_SIZE;
+		  _vec_len (fragments_to_loopback) = len - VLIB_FRAME_SIZE;
+		}
+	    }
+       }
+
+      vlib_put_next_frame (vm, node, next_index, n_left_to_next);
+    }
+
+  vlib_node_increment_counter (vm, nat44_out2in_reass_node.index,
+                               SNAT_OUT2IN_ERROR_OUT2IN_PACKETS,
+                               pkts_processed);
+
+  nat_send_all_to_node (vm, fragments_to_drop, node,
+                        &node->errors[SNAT_OUT2IN_ERROR_DROP_FRAGMENT],
+                        SNAT_OUT2IN_NEXT_DROP);
+
+  vec_free (fragments_to_drop);
+  vec_free (fragments_to_loopback);
+  return frame->n_vectors;
+}
+
+VLIB_REGISTER_NODE (nat44_ed_out2in_reass_node) = {
+  .function = nat44_ed_out2in_reass_node_fn,
+  .name = "nat44-ed-out2in-reass",
+  .vector_size = sizeof (u32),
+  .format_trace = format_nat44_out2in_reass_trace,
+  .type = VLIB_NODE_TYPE_INTERNAL,
+
+  .n_errors = ARRAY_LEN(snat_out2in_error_strings),
+  .error_strings = snat_out2in_error_strings,
+
+  .n_next_nodes = NAT44_ED_OUT2IN_N_NEXT,
+
+  /* edit / add dispositions here */
+  .next_nodes = {
+    [NAT44_ED_OUT2IN_NEXT_DROP] = "error-drop",
+    [NAT44_ED_OUT2IN_NEXT_LOOKUP] = "ip4-lookup",
+    [NAT44_ED_OUT2IN_NEXT_SLOW_PATH] = "nat44-ed-out2in-slowpath",
+    [NAT44_ED_OUT2IN_NEXT_ICMP_ERROR] = "ip4-icmp-error",
+    [NAT44_ED_OUT2IN_NEXT_IN2OUT] = "nat44-ed-in2out",
+    [NAT44_ED_OUT2IN_NEXT_REASS] = "nat44-ed-out2in-reass",
+  },
+};
+
+VLIB_NODE_FUNCTION_MULTIARCH (nat44_ed_out2in_reass_node,
+                              nat44_ed_out2in_reass_node_fn);
+
 /**************************/
 /*** deterministic mode ***/
 /**************************/