vppinfra: add mapped pcap file support

Type: feature

Change-Id: Ic720d56a6f8901efde2a58519bc9aa553205a9a6
Signed-off-by: Gary Boon <gboon@cisco.com>
Signed-off-by: Dave Barach <dave@barachs.net>

6 files changed, 822 insertions, 0 deletions

diff --git a/src/plugins/unittest/CMakeLists.txt b/src/plugins/unittest/CMakeLists.txt
index 5ba21bd7acb..e074d317b0a 100644
--- a/src/plugins/unittest/CMakeLists.txt
+++ b/src/plugins/unittest/CMakeLists.txt
@@ -28,6 +28,7 @@ add_vpp_plugin(unittest
   lisp_cp_test.c
   llist_test.c
   mactime_test.c
+  mpcap_node.c
   mfib_test.c
   punt_test.c
   rbtree_test.c
diff --git a/src/plugins/unittest/mpcap_node.c b/src/plugins/unittest/mpcap_node.c
new file mode 100644
index 00000000000..8c0bc8677be
--- /dev/null
+++ b/src/plugins/unittest/mpcap_node.c
@@ -0,0 +1,260 @@
+/*
+ * mpcap_node.c - unit-test plugin mapped pcap test node
+ *
+ * Copyright (c) <current-year> <your-organization>
+ * 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 <vlib/vlib.h>
+#include <vnet/vnet.h>
+#include <vnet/pg/pg.h>
+#include <vppinfra/error.h>
+#include <vppinfra/mpcap.h>
+#include <vnet/ethernet/ethernet.h>
+
+static mpcap_main_t test_mpcap_main = {
+  .file_name = "/tmp/mpcap_unittest.pcap",
+  .n_packets_to_capture = 15,
+  .packet_type = MPCAP_PACKET_TYPE_ethernet,
+};
+
+typedef struct
+{
+  u32 sw_if_index;
+  u32 next_index;
+} mpcap_trace_t;
+
+#ifndef CLIB_MARCH_VARIANT
+
+/* packet trace format function */
+static u8 *
+format_mpcap_trace (u8 * s, va_list * args)
+{
+  CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
+  CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
+  mpcap_trace_t *t = va_arg (*args, mpcap_trace_t *);
+
+  s = format (s, "MPCAP: sw_if_index %d, next index %d\n",
+	      t->sw_if_index, t->next_index);
+  return s;
+}
+
+vlib_node_registration_t mpcap_node;
+
+#endif /* CLIB_MARCH_VARIANT */
+
+#define foreach_mpcap_error \
+_(PROCESSED, "Mapped pcap packets processed")
+
+typedef enum
+{
+#define _(sym,str) MPCAP_ERROR_##sym,
+  foreach_mpcap_error
+#undef _
+    MPCAP_N_ERROR,
+} mpcap_error_t;
+
+#ifndef CLIB_MARCH_VARIANT
+static char *mpcap_error_strings[] = {
+#define _(sym,string) string,
+  foreach_mpcap_error
+#undef _
+};
+#endif /* CLIB_MARCH_VARIANT */
+
+typedef enum
+{
+  MPCAP_NEXT_DROP,
+  MPCAP_N_NEXT,
+} mpcap_next_t;
+
+always_inline uword
+mpcap_inline (vlib_main_t * vm,
+	      vlib_node_runtime_t * node, vlib_frame_t * frame,
+	      int is_ip4, int is_trace)
+{
+  u32 n_left_from, *from;
+  vlib_buffer_t *bufs[VLIB_FRAME_SIZE], **b;
+  u16 nexts[VLIB_FRAME_SIZE], *next;
+  mpcap_main_t *mm = &test_mpcap_main;
+  int i = 0;
+  f64 now = vlib_time_now (vm);
+  u32 error_index = node->errors[MPCAP_ERROR_PROCESSED];
+
+  if (!(mm->flags & MPCAP_FLAG_INIT_DONE))
+    {
+      clib_error_t *error;
+
+      error = mpcap_init (mm);
+      if (error)
+	clib_error_report (error);
+      mm->flags |= MPCAP_FLAG_INIT_DONE;
+    }
+
+  from = vlib_frame_vector_args (frame);
+  n_left_from = frame->n_vectors;
+
+  vlib_get_buffers (vm, from, bufs, n_left_from);
+  b = bufs;
+  next = nexts;
+
+  while (n_left_from >= 4)
+    {
+      /* Prefetch next iteration. */
+      if (PREDICT_TRUE (n_left_from >= 8))
+	{
+	  vlib_prefetch_buffer_header (b[4], STORE);
+	  vlib_prefetch_buffer_header (b[5], STORE);
+	  vlib_prefetch_buffer_header (b[6], STORE);
+	  vlib_prefetch_buffer_header (b[7], STORE);
+	  CLIB_PREFETCH (b[4]->data, CLIB_CACHE_LINE_BYTES, STORE);
+	  CLIB_PREFETCH (b[5]->data, CLIB_CACHE_LINE_BYTES, STORE);
+	  CLIB_PREFETCH (b[6]->data, CLIB_CACHE_LINE_BYTES, STORE);
+	  CLIB_PREFETCH (b[7]->data, CLIB_CACHE_LINE_BYTES, STORE);
+	}
+
+      next[0] = 0;
+      next[1] = 0;
+      next[2] = 0;
+      next[3] = 0;
+
+      b[0]->error = error_index;
+      b[1]->error = error_index;
+      b[2]->error = error_index;
+      b[3]->error = error_index;
+
+      mpcap_add_buffer (mm, vm, now, from[i++],
+			vlib_buffer_length_in_chain (vm, b[0]));
+
+      mpcap_add_buffer (mm, vm, now, from[i++],
+			vlib_buffer_length_in_chain (vm, b[1]));
+
+      mpcap_add_buffer (mm, vm, now, from[i++],
+			vlib_buffer_length_in_chain (vm, b[2]));
+
+      mpcap_add_buffer (mm, vm, now, from[i++],
+			vlib_buffer_length_in_chain (vm, b[3]));
+
+      if (is_trace)
+	{
+	  if (b[0]->flags & VLIB_BUFFER_IS_TRACED)
+	    {
+	      mpcap_trace_t *t = vlib_add_trace (vm, node, b[0], sizeof (*t));
+	      t->next_index = next[0];
+	      t->sw_if_index = vnet_buffer (b[0])->sw_if_index[VLIB_RX];
+	    }
+	  if (b[1]->flags & VLIB_BUFFER_IS_TRACED)
+	    {
+	      mpcap_trace_t *t = vlib_add_trace (vm, node, b[1], sizeof (*t));
+	      t->next_index = next[1];
+	      t->sw_if_index = vnet_buffer (b[1])->sw_if_index[VLIB_RX];
+	    }
+	  if (b[2]->flags & VLIB_BUFFER_IS_TRACED)
+	    {
+	      mpcap_trace_t *t = vlib_add_trace (vm, node, b[2], sizeof (*t));
+	      t->next_index = next[2];
+	      t->sw_if_index = vnet_buffer (b[2])->sw_if_index[VLIB_RX];
+	    }
+	  if (b[3]->flags & VLIB_BUFFER_IS_TRACED)
+	    {
+	      mpcap_trace_t *t = vlib_add_trace (vm, node, b[3], sizeof (*t));
+	      t->next_index = next[3];
+	      t->sw_if_index = vnet_buffer (b[3])->sw_if_index[VLIB_RX];
+	    }
+	}
+
+      b += 4;
+      next += 4;
+      n_left_from -= 4;
+    }
+
+  while (n_left_from > 0)
+    {
+      mpcap_add_buffer (mm, vm, now, from[i++],
+			vlib_buffer_length_in_chain (vm, b[0]));
+      next[0] = 0;
+      b[0]->error = error_index;
+
+      if (is_trace)
+	{
+	  if (b[0]->flags & VLIB_BUFFER_IS_TRACED)
+	    {
+	      mpcap_trace_t *t = vlib_add_trace (vm, node, b[0], sizeof (*t));
+	      t->next_index = next[0];
+	      t->sw_if_index = vnet_buffer (b[0])->sw_if_index[VLIB_RX];
+	    }
+	}
+
+      b += 1;
+      next += 1;
+      n_left_from -= 1;
+    }
+
+  vlib_buffer_enqueue_to_next (vm, node, from, nexts, frame->n_vectors);
+
+  return frame->n_vectors;
+}
+
+VLIB_NODE_FN (mpcap_node) (vlib_main_t * vm, vlib_node_runtime_t * node,
+			   vlib_frame_t * frame)
+{
+  if (PREDICT_FALSE (node->flags & VLIB_NODE_FLAG_TRACE))
+    return mpcap_inline (vm, node, frame, 1 /* is_ip4 */ ,
+			 1 /* is_trace */ );
+  else
+    return mpcap_inline (vm, node, frame, 1 /* is_ip4 */ ,
+			 0 /* is_trace */ );
+}
+
+/* *INDENT-OFF* */
+#ifndef CLIB_MARCH_VARIANT
+VLIB_REGISTER_NODE (mpcap_node) =
+{
+  .name = "mpcap-unittest",
+  .vector_size = sizeof (u32),
+  .format_trace = format_mpcap_trace,
+  .format_buffer = format_ethernet_header_with_length,
+  .unformat_buffer = unformat_ethernet_header,
+
+  .type = VLIB_NODE_TYPE_INTERNAL,
+
+  .n_errors = ARRAY_LEN(mpcap_error_strings),
+  .error_strings = mpcap_error_strings,
+
+  .n_next_nodes = MPCAP_N_NEXT,
+
+  /* edit / add dispositions here */
+  .next_nodes =
+  {
+    [MPCAP_NEXT_DROP] = "error-drop",
+  },
+};
+
+static clib_error_t *
+mpcap_node_init (vlib_main_t *vm)
+{
+  /* So we can send ethernet/IP packets from the pg... */
+  ethernet_setup_node (vm, mpcap_node.index);
+  return 0;
+}
+VLIB_INIT_FUNCTION (mpcap_node_init);
+
+#endif /* CLIB_MARCH_VARIANT */
+/* *INDENT-ON* */
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */
diff --git a/src/vppinfra/CMakeLists.txt b/src/vppinfra/CMakeLists.txt
index 9c5804602a1..6cd30876fa0 100644
--- a/src/vppinfra/CMakeLists.txt
+++ b/src/vppinfra/CMakeLists.txt
@@ -56,6 +56,7 @@ set(VPPINFRA_SRCS
   macros.c
   maplog.c
   mhash.c
+  mpcap.c
   pcap.c
   pmalloc.c
   pool.c
@@ -136,6 +137,7 @@ set(VPPINFRA_HEADERS
   mhash.h
   mheap_bootstrap.h
   mheap.h
+  mpcap.h
   os.h
   pcap.h
   pcap_funcs.h
diff --git a/src/vppinfra/mpcap.c b/src/vppinfra/mpcap.c
new file mode 100644
index 00000000000..902f52f1870
--- /dev/null
+++ b/src/vppinfra/mpcap.c
@@ -0,0 +1,247 @@
+/*
+ * Copyright (c) 2019 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 <sys/fcntl.h>
+#include <vppinfra/mpcap.h>
+
+/*
+ * Unfortunately, the "make test" infra won't work with mapped pcap files.
+ * Given enough work [mostly in .py code], one could fix that.
+ */
+
+/**
+ * @file
+ * @brief mapped pcap file support
+ *
+ * Usage:
+ *
+ * <code><pre>
+ * \#include <vnet/unix/mpcap.h>
+ *
+ * static mpcap_main_t mpcap = {
+ *  .file_name = "/tmp/ip4",
+ *  .n_packets_to_capture = 2,
+ *  .packet_type = MPCAP_PACKET_TYPE_ip,
+ * };
+ * </pre></code>
+ *
+ * To add a buffer:
+ *
+ *  <code><pre>mpcap_add_buffer (&mpcap, vm, pi0, 128);</pre></code>
+ *
+ * File will be written after @c n_packets_to_capture
+ * or call to mpcap_close
+ *
+ */
+
+/**
+ * @brief Close a mapped pcap file
+ * @param mpcap_main_t * pm
+ * @return rc - clib_error_t
+ *
+ */
+clib_error_t *
+mpcap_close (mpcap_main_t * pm)
+{
+  u64 actual_size = pm->current_va - pm->file_baseva;
+
+  /* Not open? Done... */
+  if ((pm->flags & MPCAP_FLAG_INIT_DONE) == 0)
+    return 0;
+
+  (void) munmap (pm->file_baseva, pm->max_file_size);
+  pm->file_baseva = 0;
+  pm->current_va = 0;
+  pm->flags &= ~MPCAP_FLAG_INIT_DONE;
+
+  if ((pm->flags & MPCAP_FLAG_WRITE_ENABLE) == 0)
+    return 0;
+
+  if (truncate (pm->file_name, actual_size) < 0)
+    clib_unix_warning ("setting file size to %llu", actual_size);
+
+  return 0;
+}
+
+/**
+ * @brief Initialize a mapped pcap file
+ * @param mpcap_main_t * pm
+ * @return rc - clib_error_t
+ *
+ */
+clib_error_t *
+mpcap_init (mpcap_main_t * pm)
+{
+  mpcap_file_header_t *fh;
+  u8 zero = 0;
+  int fd;
+
+  if (pm->flags & MPCAP_FLAG_INIT_DONE)
+    return 0;
+
+  if (!pm->file_name)
+    pm->file_name = "/tmp/vnet.mpcap";
+
+  if (pm->flags & MPCAP_FLAG_THREAD_SAFE)
+    clib_spinlock_init (&pm->lock);
+
+  fd = open (pm->file_name, O_CREAT | O_TRUNC | O_RDWR, 0664);
+  if (fd < 0)
+    {
+      return clib_error_return_unix (0, "failed to create `%s'",
+				     pm->file_name);
+    }
+
+  if (pm->max_file_size == 0ULL)
+    pm->max_file_size = MPCAP_DEFAULT_FILE_SIZE;
+
+  /* Round to a multiple of the page size */
+  pm->max_file_size += (u64) clib_mem_get_page_size ();
+  pm->max_file_size &= ~(u64) clib_mem_get_page_size ();
+
+  /* Set file size. */
+  if (lseek (fd, pm->max_file_size - 1, SEEK_SET) == (off_t) - 1)
+    {
+      close (fd);
+      (void) unlink (pm->file_name);
+      return clib_error_return_unix (0, "file size seek");
+    }
+
+  if (write (fd, &zero, 1) != 1)
+    {
+      close (fd);
+      (void) unlink (pm->file_name);
+      return clib_error_return_unix (0, "file size write");
+    }
+
+  pm->file_baseva = mmap (0, pm->max_file_size,
+			  PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
+  if (pm->file_baseva == (u8 *) MAP_FAILED)
+    {
+      clib_error_t *error = clib_error_return_unix (0, "mmap");
+      close (fd);
+      (void) unlink (pm->file_name);
+      return error;
+    }
+  (void) close (fd);
+
+  pm->flags |= MPCAP_FLAG_INIT_DONE | MPCAP_FLAG_WRITE_ENABLE;
+  pm->n_packets_captured = 0;
+  pm->n_mpcap_data_written = 0;
+
+  /* Initialize file header */
+  fh = pm->file_header = (mpcap_file_header_t *) pm->file_baseva;
+  pm->current_va = pm->file_baseva + sizeof (*fh);
+
+  fh->magic = 0xa1b2c3d4;
+  fh->major_version = 2;
+  fh->minor_version = 4;
+  fh->time_zone = 0;
+  fh->max_packet_size_in_bytes = 1 << 16;
+  fh->packet_type = pm->packet_type;
+  return 0;
+}
+
+
+/**
+ * @brief mmap a mapped pcap file, e.g. to read from another process
+ * @param pcap_main_t *pm
+ * @return rc - clib_error_t
+ */
+clib_error_t *
+mpcap_map (mpcap_main_t * pm)
+{
+  clib_error_t *error = 0;
+  int fd = -1;
+  mpcap_file_header_t *fh;
+  mpcap_packet_header_t *ph;
+  struct stat statb;
+  u64 packets_read = 0;
+  u32 min_packet_bytes = ~0;
+  u32 max_packet_bytes = 0;
+
+  if (stat (pm->file_name, &statb) < 0)
+    {
+      error = clib_error_return_unix (0, "stat `%s'", pm->file_name);
+      goto done;
+    }
+
+  fd = open (pm->file_name, O_RDONLY);
+  if (fd < 0)
+    {
+      error = clib_error_return_unix (0, "open `%s'", pm->file_name);
+      goto done;
+    }
+
+  if (statb.st_size < sizeof (*fh) + sizeof (*ph))
+    {
+      error = clib_error_return_unix (0, "`%s' is too short", pm->file_name);
+      goto done;
+    }
+
+  pm->max_file_size = statb.st_size;
+  pm->file_baseva = mmap (0, statb.st_size, PROT_READ, MAP_SHARED, fd, 0);
+  if (pm->file_baseva == (u8 *) MAP_FAILED)
+    {
+      error = clib_error_return_unix (0, "mmap");
+      goto done;
+    }
+
+  pm->flags |= MPCAP_FLAG_INIT_DONE;
+  fh = pm->file_header = (mpcap_file_header_t *) pm->file_baseva;
+  ph = (mpcap_packet_header_t *) (fh + 1);
+
+  if (fh->magic != 0xa1b2c3d4)
+    {
+      error = clib_error_return (0, "bad magic `%s'", pm->file_name);
+      goto done;
+    }
+
+  /* for the client's convenience, count packets; compute min/max sizes */
+  while (ph < (mpcap_packet_header_t *) pm->file_baseva + pm->max_file_size)
+    {
+      if (ph->n_packet_bytes_stored_in_file == 0)
+	break;
+
+      packets_read++;
+      min_packet_bytes =
+	ph->n_packet_bytes_stored_in_file <
+	min_packet_bytes ? ph->n_packet_bytes_stored_in_file :
+	min_packet_bytes;
+      max_packet_bytes =
+	ph->n_packet_bytes_stored_in_file >
+	max_packet_bytes ? ph->n_packet_bytes_stored_in_file :
+	max_packet_bytes;
+
+      ph = (mpcap_packet_header_t *)
+	(((u8 *) (ph)) + sizeof (*ph) + ph->n_packet_bytes_stored_in_file);
+    }
+  pm->packets_read = packets_read;
+  pm->min_packet_bytes = min_packet_bytes;
+  pm->max_packet_bytes = max_packet_bytes;
+
+done:
+  if (fd >= 0)
+    close (fd);
+  return error;
+}
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */
diff --git a/src/vppinfra/mpcap.h b/src/vppinfra/mpcap.h
new file mode 100644
index 00000000000..1710702d8bd
--- /dev/null
+++ b/src/vppinfra/mpcap.h
@@ -0,0 +1,257 @@
+/*
+ * Copyright (c) 2018 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.
+ */
+
+/**
+ * @file
+ * @brief MPCAP utility definitions
+ */
+#ifndef included_vnet_mpcap_h
+#define included_vnet_mpcap_h
+
+#include <vlib/vlib.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <vppinfra/time_range.h>
+
+/**
+ * @brief Packet types supported by MPCAP
+ *
+ * null 0
+ * ethernet 1
+ * ppp 9
+ * ip 12
+ * hdlc 104
+ */
+#define foreach_vnet_mpcap_packet_type          \
+  _ (null, 0)                                   \
+  _ (ethernet, 1)                               \
+  _ (ppp, 9)                                    \
+  _ (ip, 12)                                    \
+  _ (hdlc, 104)
+
+typedef enum
+{
+#define _(f,n) MPCAP_PACKET_TYPE_##f = (n),
+  foreach_vnet_mpcap_packet_type
+#undef _
+} mpcap_packet_type_t;
+
+#define foreach_mpcap_file_header                       \
+  /** 0xa1b2c3d4 host byte order.                       \
+     0xd4c3b2a1 => need to byte swap everything. */     \
+  _ (u32, magic)                                        \
+                                                        \
+  /** Currently major 2 minor 4. */                     \
+  _ (u16, major_version)                                \
+  _ (u16, minor_version)                                \
+                                                        \
+  /** 0 for GMT. */                                     \
+  _ (u32, time_zone)                                    \
+                                                        \
+  /** Accuracy of timestamps.  Typically set to 0. */   \
+  _ (u32, sigfigs)                                      \
+                                                        \
+  /** Size of largest packet in file. */                \
+  _ (u32, max_packet_size_in_bytes)                     \
+                                                        \
+  /** One of vnet_mpcap_packet_type_t. */               \
+  _ (u32, packet_type)
+
+/** File header struct */
+typedef struct
+{
+#define _(t, f) t f;
+  foreach_mpcap_file_header
+#undef _
+} mpcap_file_header_t;
+
+#define foreach_mpcap_packet_header             \
+  /** Time stamp in seconds  */                 \
+  _ (u32, time_in_sec)                          \
+  /** Time stamp in microseconds. */            \
+  _ (u32, time_in_usec)                         \
+                                                \
+  /** Number of bytes stored in file. */        \
+  _ (u32, n_packet_bytes_stored_in_file)        \
+  /** Number of bytes in actual packet. */	\
+  _ (u32, n_bytes_in_packet)
+
+/** Packet header. */
+typedef struct
+{
+#define _(t, f) t f;
+  foreach_mpcap_packet_header
+#undef _
+  /** Packet data follows. */
+  u8 data[0];
+} mpcap_packet_header_t;
+
+/**
+ * @brief MPCAP main state data structure
+ */
+typedef struct
+{
+  /** File name of mpcap output. */
+  char *file_name;
+
+  /** spinlock, initialized if flagged MPCAP_FLAG_THREAD_SAFE */
+  clib_spinlock_t lock;
+
+  /** Number of packets to capture. */
+  u32 n_packets_to_capture;
+
+  /** Packet type */
+  mpcap_packet_type_t packet_type;
+
+  /** Maximum file size */
+  u64 max_file_size;
+
+  /** Base address */
+  u8 *file_baseva;
+
+  /** current memory address */
+  u8 *current_va;
+
+  /** Number of packets currently captured. */
+  u32 n_packets_captured;
+
+  /** Pointer to file header in svm, for ease of updating */
+  mpcap_file_header_t *file_header;
+
+  /** flags */
+  u32 flags;
+#define MPCAP_FLAG_INIT_DONE (1 << 0)
+#define MPCAP_FLAG_THREAD_SAFE (1 << 1)
+#define MPCAP_FLAG_WRITE_ENABLE (1 << 2)
+
+  /** Bytes written */
+  u32 n_mpcap_data_written;
+
+  /** Vector of mpcap data. */
+  u8 *mpcap_data;
+
+  /** Packets in mapped mpcap file. */
+  u64 packets_read;
+
+  /** Min/Max Packet bytes */
+  u32 min_packet_bytes, max_packet_bytes;
+} mpcap_main_t;
+
+/* Some sensible default size */
+#define MPCAP_DEFAULT_FILE_SIZE (10<<20)
+
+/** initialize a mpcap file (for writing) */
+clib_error_t *mpcap_init (mpcap_main_t * pm);
+
+/** Flush / unmap a mpcap file */
+clib_error_t *mpcap_close (mpcap_main_t * pm);
+
+/** mmap a mpcap data file. */
+clib_error_t *mpcap_map (mpcap_main_t * pm);
+
+/**
+ * @brief Add packet
+ *
+ * @param *pm - mpcap_main_t
+ * @param time_now - f64
+ * @param n_bytes_in_trace - u32
+ * @param n_bytes_in_packet - u32
+ *
+ * @return Packet Data
+ *
+ */
+static inline void *
+mpcap_add_packet (mpcap_main_t * pm,
+		  f64 time_now, u32 n_bytes_in_trace, u32 n_bytes_in_packet)
+{
+  mpcap_packet_header_t *h;
+  u8 *d;
+
+  /* File already closed? */
+  if (PREDICT_FALSE (pm->flags & MPCAP_FLAG_INIT_DONE) == 0)
+    return 0;
+
+  d = pm->current_va;
+  pm->current_va += sizeof (h[0]) + n_bytes_in_trace;
+
+  /* Out of space? */
+  if (PREDICT_FALSE (pm->current_va >= pm->file_baseva + pm->max_file_size))
+    return 0;
+  h = (void *) (d);
+  h->time_in_sec = time_now;
+  h->time_in_usec = 1e6 * (time_now - h->time_in_sec);
+  h->n_packet_bytes_stored_in_file = n_bytes_in_trace;
+  h->n_bytes_in_packet = n_bytes_in_packet;
+  pm->n_packets_captured++;
+  return h->data;
+}
+
+/**
+ * @brief Add buffer (vlib_buffer_t) to the trace
+ *
+ * @param *pm - mpcap_main_t
+ * @param *vm - vlib_main_t
+ * @param time_now - f64
+ * @param buffer_index - u32
+ * @param n_bytes_in_trace - u32
+ *
+ */
+static inline void
+mpcap_add_buffer (mpcap_main_t * pm,
+		  vlib_main_t * vm,
+		  f64 time_now, u32 buffer_index, u32 n_bytes_in_trace)
+{
+  vlib_buffer_t *b = vlib_get_buffer (vm, buffer_index);
+  u32 n = vlib_buffer_length_in_chain (vm, b);
+  i32 n_left = clib_min (n_bytes_in_trace, n);
+  void *d;
+
+  clib_spinlock_lock_if_init (&pm->lock);
+
+  d = mpcap_add_packet (pm, time_now, n_left, n);
+  if (PREDICT_FALSE (d == 0))
+    {
+      mpcap_close (pm);
+      clib_spinlock_unlock_if_init (&pm->lock);
+      return;
+    }
+
+  while (1)
+    {
+      u32 copy_length = clib_min ((u32) n_left, b->current_length);
+      clib_memcpy (d, b->data + b->current_data, copy_length);
+      n_left -= b->current_length;
+      if (n_left <= 0)
+	break;
+      d += b->current_length;
+      ASSERT (b->flags & VLIB_BUFFER_NEXT_PRESENT);
+      b = vlib_get_buffer (vm, b->next_buffer);
+    }
+  if (pm->n_packets_captured >= pm->n_packets_to_capture)
+    mpcap_close (pm);
+
+  clib_spinlock_unlock_if_init (&pm->lock);
+}
+
+#endif /* included_vnet_mpcap_h */
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */
diff --git a/test/test_mpcap.py b/test/test_mpcap.py
new file mode 100644
index 00000000000..466e663c799
--- /dev/null
+++ b/test/test_mpcap.py
@@ -0,0 +1,55 @@
+#!/usr/bin/env python
+
+import unittest
+
+from framework import VppTestCase, VppTestRunner, running_extended_tests
+from vpp_ip_route import VppIpTable, VppIpRoute, VppRoutePath
+import os
+
+
+class TestMpcap(VppTestCase):
+    """ Mpcap Unit Test Cases """
+
+    @classmethod
+    def setUpClass(cls):
+        super(TestMpcap, cls).setUpClass()
+
+    @classmethod
+    def tearDownClass(cls):
+        super(TestMpcap, cls).tearDownClass()
+
+    def setUp(self):
+        super(TestMpcap, self).setUp()
+
+    def tearDown(self):
+        super(TestMpcap, self).tearDown()
+
+    def test_mpcap_unittest(self):
+        """ Mapped pcap file test """
+        cmds = ["packet-generator new {\n"
+                " name mpcap\n"
+                " limit 15\n"
+                " size 128-128\n"
+                " interface local0\n"
+                " node mpcap-unittest\n"
+                " data {\n"
+                "   IP6: 00:d0:2d:5e:86:85 -> 00:0d:ea:d0:00:00\n"
+                "   ICMP: db00::1 -> db00::2\n"
+                "   incrementing 30\n"
+                "   }\n",
+                "trace add pg-input 15",
+                "pa en",
+                "show trace",
+                "show error"]
+
+        for cmd in cmds:
+            self.logger.info(self.vapi.cli(cmd))
+
+        size = os.path.getsize("/tmp/mpcap_unittest.pcap")
+        os.remove("/tmp/mpcap_unittest.pcap")
+        if size != 2184:
+            self.logger.critical("BUG: file size %d not 2184" % size)
+            self.assertNotIn('WrongMPCAPFileSize', 'WrongMPCAPFileSize')
+
+if __name__ == '__main__':
+    unittest.main(testRunner=VppTestRunner)