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

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

1 files changed, 240 insertions, 25 deletions

diff --git a/src/plugins/nat/nat.c b/src/plugins/nat/nat.c
index c3583cabc21..d4c266a2b16 100755
--- a/src/plugins/nat/nat.c
+++ b/src/plugins/nat/nat.c
@@ -178,9 +178,27 @@ vlib_node_registration_t nat44_ed_classify_node;
 vlib_node_registration_t nat44_det_classify_node;
 vlib_node_registration_t nat44_handoff_classify_node;
 
+#define foreach_nat44_classify_error                      \
+_(MAX_REASS, "Maximum reassemblies exceeded")             \
+_(MAX_FRAG, "Maximum fragments per reassembly exceeded")
+
+typedef enum {
+#define _(sym,str) NAT44_CLASSIFY_ERROR_##sym,
+  foreach_nat44_classify_error
+#undef _
+  NAT44_CLASSIFY_N_ERROR,
+} nat44_classify_error_t;
+
+static char * nat44_classify_error_strings[] = {
+#define _(sym,string) string,
+  foreach_nat44_classify_error
+#undef _
+};
+
 typedef enum {
   NAT44_CLASSIFY_NEXT_IN2OUT,
   NAT44_CLASSIFY_NEXT_OUT2IN,
+  NAT44_CLASSIFY_NEXT_DROP,
   NAT44_CLASSIFY_N_NEXT,
 } nat44_classify_next_t;
 
@@ -438,6 +456,7 @@ nat_ed_session_alloc (snat_main_t *sm, snat_user_t *u, u32 thread_index)
 
 typedef struct {
   u8 next_in2out;
+  u8 cached;
 } nat44_classify_trace_t;
 
 static u8 * format_nat44_classify_trace (u8 * s, va_list * args)
@@ -447,9 +466,13 @@ static u8 * format_nat44_classify_trace (u8 * s, va_list * args)
   nat44_classify_trace_t *t = va_arg (*args, nat44_classify_trace_t *);
   char *next;
 
-  next = t->next_in2out ? "nat44-in2out" : "nat44-out2in";
-
-  s = format (s, "nat44-classify: next %s", next);
+  if (t->cached)
+    s = format (s, "nat44-classify: fragment cached");
+  else
+    {
+      next = t->next_in2out ? "nat44-in2out" : "nat44-out2in";
+      s = format (s, "nat44-classify: next %s", next);
+    }
 
   return s;
 }
@@ -466,6 +489,8 @@ nat44_classify_node_fn_inline (vlib_main_t * vm,
   snat_static_mapping_t *m;
   u32 thread_index = vm->thread_index;
   snat_main_per_thread_data_t *tsm = &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;
@@ -489,6 +514,8 @@ nat44_classify_node_fn_inline (vlib_main_t * vm,
           clib_bihash_kv_8_8_t kv0, value0;
           clib_bihash_kv_16_8_t ed_kv0, ed_value0;
           udp_header_t *udp0;
+          nat_reass_ip4_t *reass0;
+          u8 cached0 = 0;
 
           /* speculatively enqueue b0 to the current next frame */
 	  bi0 = from[0];
@@ -502,17 +529,102 @@ nat44_classify_node_fn_inline (vlib_main_t * vm,
           ip0 = vlib_buffer_get_current (b0);
           udp0 = ip4_next_header (ip0);
 
-          if (is_ed)
+          if (is_ed && ip0->protocol != IP_PROTOCOL_ICMP)
             {
-              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);
-              make_ed_kv (&ed_kv0, &ip0->src_address, &ip0->dst_address,
-                          ip0->protocol, rx_fib_index0, udp0->src_port,
-                          udp0->dst_port);
-              if (!clib_bihash_search_16_8 (&tsm->in2out_ed, &ed_kv0, &ed_value0))
-                goto enqueue0;
+              if (!ip4_is_fragment (ip0) || ip4_is_first_fragment (ip0))
+                {
+                  /* process leading fragment/whole packet (with L4 header) */
+                  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);
+                  make_ed_kv (&ed_kv0, &ip0->src_address, &ip0->dst_address,
+                              ip0->protocol, rx_fib_index0, udp0->src_port,
+                              udp0->dst_port);
+                  if (ip4_is_fragment (ip0))
+                    {
+		      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_CLASSIFY_NEXT_DROP;
+		          b0->error = node->errors[NAT44_CLASSIFY_ERROR_MAX_REASS];
+		          nat_log_notice ("maximum reassemblies exceeded");
+		          goto enqueue0;
+		        }
+                      if (!clib_bihash_search_16_8 (&tsm->in2out_ed, &ed_kv0,
+                                                    &ed_value0))
+                        {
+                          /* session exists so classify as IN2OUT,
+                           * save this information for future fragments and set
+                           * past fragments to be looped over and reprocessed */
+                          reass0->sess_index = ed_value0.value;
+                          reass0->classify_next = NAT_REASS_IP4_CLASSIFY_NEXT_IN2OUT;
+                          nat_ip4_reass_get_frags (reass0,
+                                                   &fragments_to_loopback);
+                          goto enqueue0;
+                        }
+                      else
+                        {
+                          /* session doesn't exist so continue in the code,
+                           * save this information for future fragments and set
+                           * past fragments to be looped over and reprocessed */
+                          reass0->flags |= NAT_REASS_FLAG_CLASSIFY_ED_CONTINUE;
+                          nat_ip4_reass_get_frags (reass0,
+                                                   &fragments_to_loopback);
+                        }
+                    }
+                  else
+                    {
+                      /* process whole packet */
+                      if (!clib_bihash_search_16_8 (&tsm->in2out_ed, &ed_kv0,
+                                                    &ed_value0))
+                        goto enqueue0;
+                      /* session doesn't exist so continue in code */
+                    }
+                }
+              else
+                {
+                  /* process non-first fragment */
+                  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_CLASSIFY_NEXT_DROP;
+                      b0->error = node->errors[NAT44_CLASSIFY_ERROR_MAX_REASS];
+                      nat_log_notice ("maximum reassemblies exceeded");
+                      goto enqueue0;
+                    }
+                  /* check if first fragment has arrived */
+                  if (reass0->classify_next == NAT_REASS_IP4_CLASSIFY_NONE &&
+                      !(reass0->flags & NAT_REASS_FLAG_CLASSIFY_ED_CONTINUE))
+                    {
+                      /* first fragment still hasn't arrived, cache this fragment */
+		      if (nat_ip4_reass_add_fragment (reass0, bi0,
+				                      &fragments_to_drop))
+		        {
+		          b0->error = node->errors[NAT44_CLASSIFY_ERROR_MAX_FRAG];
+		          nat_log_notice ("maximum fragments per reassembly exceeded");
+		          next0 = NAT44_CLASSIFY_NEXT_DROP;
+		          goto enqueue0;
+		        }
+		      cached0 = 1;
+		      goto enqueue0;
+                    }
+                  if (reass0->classify_next == NAT_REASS_IP4_CLASSIFY_NEXT_IN2OUT)
+                    goto enqueue0;
+                  /* flag NAT_REASS_FLAG_CLASSIFY_ED_CONTINUE is set
+                   * so keep the default next0 and continue in code to
+                   * potentially find other classification for this packet */
+                }
             }
 
           vec_foreach (ap, sm->addresses)
@@ -531,21 +643,86 @@ nat44_classify_node_fn_inline (vlib_main_t * vm,
               m_key0.protocol = 0;
               m_key0.fib_index = 0;
               kv0.key = m_key0.as_u64;
-              if (!clib_bihash_search_8_8 (&sm->static_mapping_by_external, &kv0, &value0))
+              /* try to classify the fragment based on IP header alone */
+              if (!clib_bihash_search_8_8 (&sm->static_mapping_by_external,
+                                           &kv0, &value0))
                 {
                   m = pool_elt_at_index (sm->static_mappings, value0.value);
                   if (m->local_addr.as_u32 != m->external_addr.as_u32)
                     next0 = NAT44_CLASSIFY_NEXT_OUT2IN;
                   goto enqueue0;
                 }
-              m_key0.port = clib_net_to_host_u16 (udp0->dst_port);
-              m_key0.protocol = ip_proto_to_snat_proto (ip0->protocol);
-              kv0.key = m_key0.as_u64;
-              if (!clib_bihash_search_8_8 (&sm->static_mapping_by_external, &kv0, &value0))
+              if (!ip4_is_fragment (ip0) || ip4_is_first_fragment (ip0))
                 {
-                  m = pool_elt_at_index (sm->static_mappings, value0.value);
-                  if (m->local_addr.as_u32 != m->external_addr.as_u32)
+                  /* process leading fragment/whole packet (with L4 header) */
+                  m_key0.port = clib_net_to_host_u16 (udp0->dst_port);
+                  m_key0.protocol = ip_proto_to_snat_proto (ip0->protocol);
+                  kv0.key = m_key0.as_u64;
+                  if (!clib_bihash_search_8_8 (&sm->static_mapping_by_external,
+                                               &kv0, &value0))
+                    {
+                      m = pool_elt_at_index (sm->static_mappings, value0.value);
+                      if (m->local_addr.as_u32 != m->external_addr.as_u32)
+                        next0 = NAT44_CLASSIFY_NEXT_OUT2IN;
+                    }
+                  if (ip4_is_fragment (ip0))
+                    {
+		      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_CLASSIFY_NEXT_DROP;
+		          b0->error = node->errors[NAT44_CLASSIFY_ERROR_MAX_REASS];
+		          nat_log_notice ("maximum reassemblies exceeded");
+		          goto enqueue0;
+		        }
+                      /* save classification for future fragments and set past
+                       * fragments to be looped over and reprocessed */
+		      if (next0 == NAT44_CLASSIFY_NEXT_OUT2IN)
+		        reass0->classify_next = NAT_REASS_IP4_CLASSIFY_NEXT_OUT2IN;
+		      else
+			reass0->classify_next = NAT_REASS_IP4_CLASSIFY_NEXT_IN2OUT;
+		      nat_ip4_reass_get_frags (reass0, &fragments_to_loopback);
+                    }
+                }
+              else
+                {
+                  /* process non-first fragment */
+                  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_CLASSIFY_NEXT_DROP;
+                      b0->error = node->errors[NAT44_CLASSIFY_ERROR_MAX_REASS];
+                      nat_log_notice ("maximum reassemblies exceeded");
+                      goto enqueue0;
+                    }
+                  if (reass0->classify_next == NAT_REASS_IP4_CLASSIFY_NONE)
+                    /* first fragment still hasn't arrived */
+                    {
+		      if (nat_ip4_reass_add_fragment (reass0, bi0,
+				                      &fragments_to_drop))
+		        {
+		          b0->error = node->errors[NAT44_CLASSIFY_ERROR_MAX_FRAG];
+		          nat_log_notice ("maximum fragments per reassembly exceeded");
+		          next0 = NAT44_CLASSIFY_NEXT_DROP;
+		          goto enqueue0;
+		        }
+		      cached0 = 1;
+		      goto enqueue0;
+                    }
+                  else if (reass0->classify_next == NAT_REASS_IP4_CLASSIFY_NEXT_OUT2IN)
                     next0 = NAT44_CLASSIFY_NEXT_OUT2IN;
+                  else if (reass0->classify_next == NAT_REASS_IP4_CLASSIFY_NEXT_IN2OUT)
+                    next0 = NAT44_CLASSIFY_NEXT_IN2OUT;
                 }
             }
 
@@ -555,18 +732,50 @@ nat44_classify_node_fn_inline (vlib_main_t * vm,
             {
               nat44_classify_trace_t *t =
                   vlib_add_trace (vm, node, b0, sizeof (*t));
-              t->next_in2out = next0 == NAT44_CLASSIFY_NEXT_IN2OUT ? 1 : 0;
+              t->cached = cached0;
+              if (!cached0)
+                t->next_in2out = next0 == NAT44_CLASSIFY_NEXT_IN2OUT ? 1 : 0;
             }
 
-          /* 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 (cached0)
+            {
+              n_left_to_next++;
+              to_next--;
+            }
+          else
+            /* 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);
     }
 
+  nat_send_all_to_node (vm, fragments_to_drop, node, 0, NAT44_CLASSIFY_NEXT_DROP);
+
+  vec_free (fragments_to_drop);
+
   return frame->n_vectors;
 }
 
@@ -584,10 +793,13 @@ VLIB_REGISTER_NODE (nat44_classify_node) = {
   .vector_size = sizeof (u32),
   .format_trace = format_nat44_classify_trace,
   .type = VLIB_NODE_TYPE_INTERNAL,
+  .n_errors = ARRAY_LEN(nat44_classify_error_strings),
+  .error_strings = nat44_classify_error_strings,
   .n_next_nodes = NAT44_CLASSIFY_N_NEXT,
   .next_nodes = {
     [NAT44_CLASSIFY_NEXT_IN2OUT] = "nat44-in2out",
     [NAT44_CLASSIFY_NEXT_OUT2IN] = "nat44-out2in",
+    [NAT44_CLASSIFY_NEXT_DROP] = "error-drop",
   },
 };
 
@@ -611,6 +823,7 @@ VLIB_REGISTER_NODE (nat44_ed_classify_node) = {
   .next_nodes = {
     [NAT44_CLASSIFY_NEXT_IN2OUT] = "nat44-ed-in2out",
     [NAT44_CLASSIFY_NEXT_OUT2IN] = "nat44-ed-out2in",
+    [NAT44_CLASSIFY_NEXT_DROP] = "error-drop",
   },
 };
 
@@ -635,6 +848,7 @@ VLIB_REGISTER_NODE (nat44_det_classify_node) = {
   .next_nodes = {
     [NAT44_CLASSIFY_NEXT_IN2OUT] = "nat44-det-in2out",
     [NAT44_CLASSIFY_NEXT_OUT2IN] = "nat44-det-out2in",
+    [NAT44_CLASSIFY_NEXT_DROP] = "error-drop",
   },
 };
 
@@ -659,6 +873,7 @@ VLIB_REGISTER_NODE (nat44_handoff_classify_node) = {
   .next_nodes = {
     [NAT44_CLASSIFY_NEXT_IN2OUT] = "nat44-in2out-worker-handoff",
     [NAT44_CLASSIFY_NEXT_OUT2IN] = "nat44-out2in-worker-handoff",
+    [NAT44_CLASSIFY_NEXT_DROP] = "error-drop",
   },
 };