NAT: DS-Lite (VPP-1040)

Dual-Stack Lite enables a broadband service provider to share IPv4 addresses among customers by combining two well-known technologies: IPv4-in-IPv6 and NAT.

Change-Id: I039740f8548c623cd1ac89b8ecda1a6cc4aafb9c
Signed-off-by: Matus Fabian <matfabia@cisco.com>

1 files changed, 297 insertions, 0 deletions

diff --git a/src/plugins/nat/dslite_out2in.c b/src/plugins/nat/dslite_out2in.c
new file mode 100644
index 00000000000..802b2a91544
--- /dev/null
+++ b/src/plugins/nat/dslite_out2in.c
@@ -0,0 +1,297 @@
+/*
+ * Copyright (c) 2017 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#include <nat/dslite.h>
+
+vlib_node_registration_t dslite_out2in_node;
+
+typedef enum
+{
+  DSLITE_OUT2IN_NEXT_IP4_LOOKUP,
+  DSLITE_OUT2IN_NEXT_IP6_LOOKUP,
+  DSLITE_OUT2IN_NEXT_DROP,
+  DSLITE_OUT2IN_N_NEXT,
+} dslite_out2in_next_t;
+
+static char *dslite_out2in_error_strings[] = {
+#define _(sym,string) string,
+  foreach_dslite_error
+#undef _
+};
+
+static inline u32
+dslite_icmp_out2in (dslite_main_t * dm, ip4_header_t * ip4,
+		    dslite_session_t ** sp, u32 next, u8 * error,
+		    u32 thread_index)
+{
+  dslite_session_t *s = 0;
+  icmp46_header_t *icmp = ip4_next_header (ip4);
+  clib_bihash_kv_8_8_t kv, value;
+  snat_session_key_t key;
+  u32 n = next;
+  icmp_echo_header_t *echo;
+  u32 new_addr, old_addr;
+  u16 old_id, new_id;
+  ip_csum_t sum;
+
+  echo = (icmp_echo_header_t *) (icmp + 1);
+
+  if (icmp_is_error_message (icmp) || (icmp->type != ICMP4_echo_reply))
+    {
+      n = DSLITE_OUT2IN_NEXT_DROP;
+      *error = DSLITE_ERROR_BAD_ICMP_TYPE;
+      goto done;
+    }
+
+  key.addr = ip4->dst_address;
+  key.port = echo->identifier;
+  key.protocol = SNAT_PROTOCOL_ICMP;
+  key.fib_index = 0;
+  kv.key = key.as_u64;
+
+  if (clib_bihash_search_8_8
+      (&dm->per_thread_data[thread_index].out2in, &kv, &value))
+    {
+      next = DSLITE_OUT2IN_NEXT_DROP;
+      *error = DSLITE_ERROR_NO_TRANSLATION;
+      goto done;
+    }
+  else
+    {
+      s =
+	pool_elt_at_index (dm->per_thread_data[thread_index].sessions,
+			   value.value);
+    }
+
+  old_id = echo->identifier;
+  echo->identifier = new_id = s->in2out.port;
+  sum = icmp->checksum;
+  sum = ip_csum_update (sum, old_id, new_id, icmp_echo_header_t, identifier);
+  icmp->checksum = ip_csum_fold (sum);
+
+  old_addr = ip4->dst_address.as_u32;
+  ip4->dst_address = s->in2out.addr;
+  new_addr = ip4->dst_address.as_u32;
+
+  sum = ip4->checksum;
+  sum = ip_csum_update (sum, old_addr, new_addr, ip4_header_t, dst_address);
+  ip4->checksum = ip_csum_fold (sum);
+
+done:
+  *sp = s;
+  return n;
+}
+
+static uword
+dslite_out2in_node_fn (vlib_main_t * vm, vlib_node_runtime_t * node,
+		       vlib_frame_t * frame)
+{
+  u32 n_left_from, *from, *to_next;
+  dslite_out2in_next_t next_index;
+  vlib_node_runtime_t *error_node;
+  u32 thread_index = vlib_get_thread_index ();
+  f64 now = vlib_time_now (vm);
+  dslite_main_t *dm = &dslite_main;
+
+  error_node = vlib_node_get_runtime (vm, dslite_out2in_node.index);
+
+  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;
+	  vlib_buffer_t *b0;
+	  u32 next0 = DSLITE_OUT2IN_NEXT_IP6_LOOKUP;
+	  u8 error0 = DSLITE_ERROR_OUT2IN;
+	  ip4_header_t *ip40;
+	  ip6_header_t *ip60;
+	  u32 proto0;
+	  udp_header_t *udp0;
+	  tcp_header_t *tcp0;
+	  clib_bihash_kv_8_8_t kv0, value0;
+	  snat_session_key_t key0;
+	  dslite_session_t *s0 = 0;
+	  ip_csum_t sum0;
+	  u32 new_addr0, old_addr0;
+	  u16 new_port0, old_port0;
+
+	  /* 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);
+	  ip40 = vlib_buffer_get_current (b0);
+	  proto0 = ip_proto_to_snat_proto (ip40->protocol);
+
+	  if (PREDICT_FALSE (proto0 == ~0))
+	    {
+	      error0 = DSLITE_ERROR_UNSUPPORTED_PROTOCOL;
+	      next0 = DSLITE_OUT2IN_NEXT_DROP;
+	      goto trace0;
+	    }
+
+	  if (PREDICT_FALSE (proto0 == SNAT_PROTOCOL_ICMP))
+	    {
+	      next0 =
+		dslite_icmp_out2in (dm, ip40, &s0, next0, &error0,
+				    thread_index);
+	      if (PREDICT_FALSE (next0 == DSLITE_OUT2IN_NEXT_DROP))
+		goto trace0;
+
+	      goto encap0;
+	    }
+
+	  udp0 = ip4_next_header (ip40);
+	  tcp0 = (tcp_header_t *) udp0;
+
+	  key0.addr = ip40->dst_address;
+	  key0.port = udp0->dst_port;
+	  key0.protocol = proto0;
+	  key0.fib_index = 0;
+	  kv0.key = key0.as_u64;
+
+	  if (clib_bihash_search_8_8
+	      (&dm->per_thread_data[thread_index].out2in, &kv0, &value0))
+	    {
+	      next0 = DSLITE_OUT2IN_NEXT_DROP;
+	      error0 = DSLITE_ERROR_NO_TRANSLATION;
+	      goto trace0;
+	    }
+	  else
+	    {
+	      s0 =
+		pool_elt_at_index (dm->per_thread_data[thread_index].sessions,
+				   value0.value);
+	    }
+
+	  old_addr0 = ip40->dst_address.as_u32;
+	  ip40->dst_address = s0->in2out.addr;
+	  new_addr0 = ip40->dst_address.as_u32;
+
+	  sum0 = ip40->checksum;
+	  sum0 =
+	    ip_csum_update (sum0, old_addr0, new_addr0, ip4_header_t,
+			    dst_address);
+	  ip40->checksum = ip_csum_fold (sum0);
+
+	  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);
+	      sum0 =
+		ip_csum_update (sum0, old_port0, new_port0, ip4_header_t,
+				length);
+	      tcp0->checksum = ip_csum_fold (sum0);
+	    }
+	  else
+	    {
+	      old_port0 = udp0->dst_port;
+	      udp0->dst_port = s0->in2out.port;
+	      udp0->checksum = 0;
+	    }
+
+	encap0:
+	  /* Construct IPv6 header */
+	  vlib_buffer_advance (b0, -(sizeof (ip6_header_t)));
+	  ip60 = vlib_buffer_get_current (b0);
+	  ip60->ip_version_traffic_class_and_flow_label =
+	    clib_host_to_net_u32 ((6 << 28) + (ip40->tos << 20));
+	  ip60->payload_length = ip40->length;
+	  ip60->protocol = IP_PROTOCOL_IP_IN_IP;
+	  ip60->hop_limit = ip40->ttl;
+	  ip60->src_address.as_u64[0] = dm->aftr_ip6_addr.as_u64[0];
+	  ip60->src_address.as_u64[1] = dm->aftr_ip6_addr.as_u64[1];
+	  ip60->dst_address.as_u64[0] = s0->in2out.softwire_id.as_u64[0];
+	  ip60->dst_address.as_u64[1] = s0->in2out.softwire_id.as_u64[1];
+
+	  /* Accounting */
+	  s0->last_heard = now;
+	  s0->total_pkts++;
+	  s0->total_bytes += vlib_buffer_length_in_chain (vm, b0);
+	  /* Per-B4 LRU list maintenance */
+	  clib_dlist_remove (dm->per_thread_data[thread_index].list_pool,
+			     s0->per_b4_index);
+	  clib_dlist_addtail (dm->per_thread_data[thread_index].list_pool,
+			      s0->per_b4_list_head_index, s0->per_b4_index);
+	trace0:
+	  if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)
+			     && (b0->flags & VLIB_BUFFER_IS_TRACED)))
+	    {
+	      dslite_trace_t *t = vlib_add_trace (vm, node, b0, sizeof (*t));
+	      t->next_index = next0;
+	      t->session_index = ~0;
+	      if (s0)
+		t->session_index =
+		  s0 - dm->per_thread_data[thread_index].sessions;
+	    }
+
+	  b0->error = error_node->errors[error0];
+
+	  /* 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);
+	}
+      vlib_put_next_frame (vm, node, next_index, n_left_to_next);
+    }
+
+  return frame->n_vectors;
+}
+
+/* *INDENT-OFF* */
+VLIB_REGISTER_NODE (dslite_out2in_node) = {
+  .function = dslite_out2in_node_fn,
+  .name = "dslite-out2in",
+  .vector_size = sizeof (u32),
+  .format_trace = format_dslite_trace,
+  .type = VLIB_NODE_TYPE_INTERNAL,
+  .n_errors = ARRAY_LEN (dslite_out2in_error_strings),
+  .error_strings = dslite_out2in_error_strings,
+  .n_next_nodes = DSLITE_OUT2IN_N_NEXT,
+  /* edit / add dispositions here */
+  .next_nodes = {
+    [DSLITE_OUT2IN_NEXT_DROP] = "error-drop",
+    [DSLITE_OUT2IN_NEXT_IP4_LOOKUP] = "ip4-lookup",
+    [DSLITE_OUT2IN_NEXT_IP6_LOOKUP] = "ip6-lookup",
+  },
+};
+/* *INDENT-ON* */
+
+VLIB_NODE_FUNCTION_MULTIARCH (dslite_out2in_node, dslite_out2in_node_fn);
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */