misc: unify pcap rx / tx / drop trace

Use a single vnet_pcap_t in vlib_global_main, specifically to support
unified tracing

Update sphinx docs, doxygen tags

Type: refactor
Ticket: VPP-1776

Signed-off-by: Dave Barach <dave@barachs.net>
Change-Id: Id15d41a596712968c0714cef1bd2cd5bc9cbdd55

6 files changed, 177 insertions, 240 deletions

diff --git a/docs/gettingstarted/developers/vnet.md b/docs/gettingstarted/developers/vnet.md
index b8f878c2cd7..826af0a90a9 100644
--- a/docs/gettingstarted/developers/vnet.md
+++ b/docs/gettingstarted/developers/vnet.md
@@ -470,25 +470,33 @@ This should be of significant value when developing new vpp graph
 nodes. If new code mispositions b->current_data, it will be completely
 obvious from looking at the dispatch trace in wireshark.
 
-## pcap rx and tx tracing
+## pcap rx, tx, and drop tracing
 
-vpp also supports rx and tx packet capture in pcap format, through the
-"pcap rx trace" and "pcap tx trace" debug CLI commands
+vpp also supports rx, tx, and drop packet capture in pcap format,
+through the "pcap trace" debug CLI command.
 
-This command is used to start or stop a packet capture, or show
-the status of packet capture. Note that both "pcap rx trace" and
-"pcap tx trace" are implemented. The command syntax is identical,
-simply substitute rx for tx as needed.
+This command is used to start or stop a packet capture, or show the
+status of packet capture. Each of "pcap trace rx", "pcap trace tx",
+and "pcap trace drop" is implemented.  Supply one or more of "rx",
+"tx", and "drop" to enable multiple simultaneous capture types.
 
 These commands have the following optional parameters:
 
-on|off- Used to start or stop a packet capture.
+- <b>rx</b> - trace received packets.
+
+- <b>tx</b> - trace transmitted packets.
+
+- <b>drop</b> - trace dropped packets.
 
 - <b>max _nnnn_</b> - file size, number of packet captures. Once
   <nnnn> packets have been received, the trace buffer buffer is flushed
   to the indicated file. Defaults to 1000. Can only be updated if packet
   capture is off.
 
+- <b>max-bytes-per-pkt _nnnn_</b> - maximum number of bytes to trace
+  on a per-paket basis. Must be >32 and less than 9000. Default value:
+  512.
+
 - <b>intfc _interface_ | _any_</b> - Used to specify a given interface,
   or use '<em>any</em>' to run packet capture on all interfaces.
   '<em>any</em>' is the default if not provided. Settings from a previous
diff --git a/src/vlib/main.h b/src/vlib/main.h
index 88ce98bb405..2b50b4e4712 100644
--- a/src/vlib/main.h
+++ b/src/vlib/main.h
@@ -60,7 +60,14 @@
 
 typedef struct
 {
-  int pcap_enable;
+  /* Trace RX pkts */
+  u8 pcap_rx_enable;
+  /* Trace TX pkts */
+  u8 pcap_tx_enable;
+  /* Trace drop pkts */
+  u8 pcap_drop_enable;
+  u8 pad1;
+  u32 max_bytes_per_pkt;
   u32 pcap_sw_if_index;
   pcap_main_t pcap_main;
   u32 filter_classify_table_index;
@@ -153,7 +160,7 @@ typedef struct vlib_main_t
   u8 *pcap_buffer;
 
   /* pcap rx / tx tracing */
-  vnet_pcap_t pcap[VLIB_N_RX_TX];
+  vnet_pcap_t pcap;
 
   /* Error handling. */
   vlib_error_main_t error_main;
diff --git a/src/vnet/ethernet/node.c b/src/vnet/ethernet/node.c
index fb706551719..ee14e40d881 100755
--- a/src/vnet/ethernet/node.c
+++ b/src/vnet/ethernet/node.c
@@ -998,10 +998,11 @@ ethernet_input_trace (vlib_main_t * vm, vlib_node_runtime_t * node,
     }
 
   /* rx pcap capture if enabled */
-  if (PREDICT_FALSE (vlib_global_main.pcap[VLIB_RX].pcap_enable))
+  if (PREDICT_FALSE (vlib_global_main.pcap.pcap_rx_enable))
     {
       u32 bi0;
       vnet_main_t *vnm = vnet_get_main ();
+      vnet_pcap_t *pp = &vlib_global_main.pcap;
 
       from = vlib_frame_vector_args (from_frame);
       n_left = from_frame->n_vectors;
@@ -1020,17 +1021,16 @@ ethernet_input_trace (vlib_main_t * vm, vlib_node_runtime_t * node,
 		(b0, vnm->classify_filter_table_indices[0],
 		 0 /* full classify */ );
 	      if (classify_filter_result)
-		pcap_add_buffer (&vlib_global_main.pcap[VLIB_RX].pcap_main,
-				 vm, bi0, 512);
+		pcap_add_buffer (&pp->pcap_main, vm, bi0,
+				 pp->max_bytes_per_pkt);
 	      continue;
 	    }
 
-	  if (vlib_global_main.pcap[VLIB_RX].pcap_sw_if_index == 0 ||
-	      vlib_global_main.pcap[VLIB_RX].pcap_sw_if_index
-	      == vnet_buffer (b0)->sw_if_index[VLIB_RX])
+	  if (pp->pcap_sw_if_index == 0 ||
+	      pp->pcap_sw_if_index == vnet_buffer (b0)->sw_if_index[VLIB_RX])
 	    {
-	      pcap_add_buffer (&vlib_global_main.pcap[VLIB_RX].pcap_main, vm,
-			       bi0, 512);
+	      pcap_add_buffer (&pp->pcap_main, vm, bi0,
+			       pp->max_bytes_per_pkt);
 	    }
 	}
     }
diff --git a/src/vnet/interface.h b/src/vnet/interface.h
index 0c273c6c7d2..00ed1f03151 100644
--- a/src/vnet/interface.h
+++ b/src/vnet/interface.h
@@ -843,12 +843,11 @@ typedef struct
 
   vnet_hw_interface_nodes_t *deleted_hw_interface_nodes;
 
-  /* pcap drop tracing */
-  int drop_pcap_enable;
-  pcap_main_t pcap_main;
-  u8 *pcap_filename;
-  u32 pcap_sw_if_index;
-  u32 pcap_pkts_to_capture;
+  /*
+   * pcap drop tracing
+   * Only the drop filter hash lives here. See ../src/vlib/main.h for
+   * the rest of the variables.
+   */
   uword *pcap_drop_filter_hash;
 
   /* Buffer metadata format helper functions */
@@ -899,7 +898,10 @@ typedef struct
   int enable;
   int status;
   u32 packets_to_capture;
-  vlib_rx_or_tx_t rxtx;
+  u32 max_bytes_per_pkt;
+  u8 rx_enable;
+  u8 tx_enable;
+  u8 drop_enable;
   u32 sw_if_index;
   int filter;
 } vnet_pcap_dispatch_trace_args_t;
diff --git a/src/vnet/interface_cli.c b/src/vnet/interface_cli.c
index 3164f7a31f2..e6b251da17f 100644
--- a/src/vnet/interface_cli.c
+++ b/src/vnet/interface_cli.c
@@ -1695,52 +1695,94 @@ VLIB_CLI_COMMAND (cmd_set_if_rx_placement,static) = {
 };
 /* *INDENT-ON* */
 
+static u8 *
+format_vnet_pcap (u8 * s, va_list * args)
+{
+  vnet_pcap_t *pp = va_arg (*args, vnet_pcap_t *);
+  int type = va_arg (*args, int);
+  int printed = 0;
+
+  if (type == 0)
+    {
+      if (pp->pcap_rx_enable)
+	{
+	  s = format (s, "rx");
+	  printed = 1;
+	}
+      if (pp->pcap_tx_enable)
+	{
+	  if (printed)
+	    s = format (s, " and ");
+	  s = format (s, "tx");
+	  printed = 1;
+	}
+      if (pp->pcap_drop_enable)
+	{
+	  if (printed)
+	    s = format (s, " and ");
+	  s = format (s, "drop");
+	  printed = 1;
+	}
+      return s;
+    }
+  s = format (s, "unknown type %d!", type);
+  return s;
+}
+
+
 int
 vnet_pcap_dispatch_trace_configure (vnet_pcap_dispatch_trace_args_t * a)
 {
   vlib_main_t *vm = vlib_get_main ();
   vnet_main_t *vnm = vnet_get_main ();
-  vlib_rx_or_tx_t rxtx = a->rxtx;
-  vnet_pcap_t *pp = &vm->pcap[rxtx];
+  vnet_pcap_t *pp = &vm->pcap;
   pcap_main_t *pm = &pp->pcap_main;
 
   if (a->status)
     {
-      if (pp->pcap_enable)
+      if (pp->pcap_rx_enable || pp->pcap_tx_enable || pp->pcap_drop_enable)
 	{
 	  vlib_cli_output
-	    (vm, "pcap %s dispatch capture enabled: %d of %d pkts...",
-	     (rxtx == VLIB_RX) ? "rx" : "tx",
+	    (vm, "pcap %U dispatch capture enabled: %d of %d pkts...",
+	     format_vnet_pcap, pp, 0 /* print type */ ,
 	     pm->n_packets_captured, pm->n_packets_to_capture);
 	  vlib_cli_output (vm, "capture to file %s", pm->file_name);
 	}
       else
-	vlib_cli_output (vm, "pcap %s dispatch capture disabled",
-			 (rxtx == VLIB_RX) ? "rx" : "tx");
+	vlib_cli_output (vm, "pcap dispatch capture disabled");
+
       return 0;
     }
 
   /* Consistency checks */
 
   /* Enable w/ capture already enabled not allowed */
-  if (pp->pcap_enable && a->enable)
+  if ((pp->pcap_rx_enable + pp->pcap_tx_enable + pp->pcap_drop_enable)
+      && (a->rx_enable + a->tx_enable + a->drop_enable))
     return VNET_API_ERROR_INVALID_VALUE;
 
   /* Disable capture with capture already disabled, not interesting */
-  if (pp->pcap_enable == 0 && a->enable == 0)
+  if (((pp->pcap_rx_enable + pp->pcap_tx_enable + pp->pcap_drop_enable) == 0)
+      && ((a->rx_enable + a->tx_enable + a->drop_enable == 0)))
     return VNET_API_ERROR_VALUE_EXIST;
 
   /* Change number of packets to capture while capturing */
-  if (pp->pcap_enable && a->enable
+  if ((pp->pcap_rx_enable + pp->pcap_tx_enable + pp->pcap_drop_enable)
+      && (a->rx_enable + a->tx_enable + a->drop_enable)
       && (pm->n_packets_to_capture != a->packets_to_capture))
     return VNET_API_ERROR_INVALID_VALUE_2;
 
-  if (a->enable && a->filter
+  /* Classify filter specified, but no classify filter configured */
+  if ((a->rx_enable + a->tx_enable + a->drop_enable) && a->filter
       && (vec_len (vnm->classify_filter_table_indices) == 0))
     return VNET_API_ERROR_NO_SUCH_LABEL;
 
-  if (a->enable)
+  if (a->rx_enable + a->tx_enable + a->drop_enable)
     {
+      /* Sanity check max bytes per pkt */
+      if (a->max_bytes_per_pkt < 32 || a->max_bytes_per_pkt > 9000)
+	return VNET_API_ERROR_INVALID_MEMORY_SIZE;
+
       /* Clean up from previous run, if any */
       vec_free (pm->file_name);
       vec_free (pm->pcap_data);
@@ -1751,8 +1793,18 @@ vnet_pcap_dispatch_trace_configure (vnet_pcap_dispatch_trace_args_t * a)
 	clib_spinlock_init (&(pm->lock));
 
       if (a->filename == 0)
-	a->filename = format (0, "/tmp/%s.pcap%c",
-			      (rxtx == VLIB_RX) ? "rx" : "tx", 0);
+	{
+	  u8 *stem = 0;
+
+	  if (a->rx_enable)
+	    stem = format (stem, "rx");
+	  if (a->tx_enable)
+	    stem = format (stem, "tx");
+	  if (a->drop_enable)
+	    stem = format (stem, "drop");
+	  a->filename = format (0, "/tmp/%s.pcap%c", stem, 0);
+	  vec_free (stem);
+	}
 
       pm->file_name = (char *) a->filename;
       pm->n_packets_captured = 0;
@@ -1764,11 +1816,16 @@ vnet_pcap_dispatch_trace_configure (vnet_pcap_dispatch_trace_args_t * a)
 	  vnm->classify_filter_table_indices[0];
       else
 	pp->filter_classify_table_index = ~0;
-      pp->pcap_enable = 1;
+      pp->pcap_rx_enable = a->rx_enable;
+      pp->pcap_tx_enable = a->tx_enable;
+      pp->pcap_drop_enable = a->drop_enable;
+      pp->max_bytes_per_pkt = a->max_bytes_per_pkt;
     }
   else
     {
-      pp->pcap_enable = 0;
+      pp->pcap_rx_enable = 0;
+      pp->pcap_tx_enable = 0;
+      pp->pcap_drop_enable = 0;
       if (pm->n_packets_captured)
 	{
 	  clib_error_t *error;
@@ -1794,17 +1851,19 @@ vnet_pcap_dispatch_trace_configure (vnet_pcap_dispatch_trace_args_t * a)
 }
 
 static clib_error_t *
-pcap_trace_command_internal (vlib_main_t * vm,
-			     unformat_input_t * input,
-			     vlib_cli_command_t * cmd, vlib_rx_or_tx_t rxtx)
+pcap_trace_command_fn (vlib_main_t * vm,
+		       unformat_input_t * input, vlib_cli_command_t * cmd)
 {
   unformat_input_t _line_input, *line_input = &_line_input;
   vnet_pcap_dispatch_trace_args_t _a, *a = &_a;
   vnet_main_t *vnm = vnet_get_main ();
   u8 *filename = 0;
   u32 max = 1000;
+  u32 max_bytes_per_pkt = 512;
   int rv;
-  int enable = 0;
+  int rx_enable = 0;
+  int tx_enable = 0;
+  int drop_enable = 0;
   int status = 0;
   int filter = 0;
   u32 sw_if_index = 0;
@@ -1815,13 +1874,16 @@ pcap_trace_command_internal (vlib_main_t * vm,
 
   while (unformat_check_input (line_input) != UNFORMAT_END_OF_INPUT)
     {
-      if (unformat (line_input, "on %=", &enable, 1))
-	;
-      else if (unformat (line_input, "enable %=", &enable, 1))
-	;
-      else if (unformat (line_input, "off %=", &enable, 0))
-	;
-      else if (unformat (line_input, "disable %=", &enable, 0))
+      if (unformat (line_input, "rx"))
+	rx_enable = 1;
+      else if (unformat (line_input, "tx"))
+	tx_enable = 1;
+      else if (unformat (line_input, "drop"))
+	drop_enable = 1;
+      else if (unformat (line_input, "off"))
+	rx_enable = tx_enable = drop_enable = 0;
+      else if (unformat (line_input, "max-bytes-per-pkt %u",
+			 &max_bytes_per_pkt))
 	;
       else if (unformat (line_input, "max %d", &max))
 	;
@@ -1850,12 +1912,14 @@ pcap_trace_command_internal (vlib_main_t * vm,
 
   /* no need for memset (a, 0, sizeof (*a)), set all fields here. */
   a->filename = filename;
-  a->enable = enable;
+  a->rx_enable = rx_enable;
+  a->tx_enable = tx_enable;
+  a->drop_enable = drop_enable;
   a->status = status;
   a->packets_to_capture = max;
-  a->rxtx = rxtx;
   a->sw_if_index = sw_if_index;
   a->filter = filter;
+  a->max_bytes_per_pkt = max_bytes_per_pkt;
 
   rv = vnet_pcap_dispatch_trace_configure (a);
 
@@ -1880,6 +1944,10 @@ pcap_trace_command_internal (vlib_main_t * vm,
     case VNET_API_ERROR_NO_SUCH_ENTRY:
       return clib_error_return (0, "No packets captured...");
 
+    case VNET_API_ERROR_INVALID_MEMORY_SIZE:
+      return clib_error_return (0,
+				"Max bytes per pkt must be > 32, < 9000...");
+
     case VNET_API_ERROR_NO_SUCH_LABEL:
       return clib_error_return
 	(0, "No classify filter configured, see 'classify filter...'");
@@ -1891,30 +1959,20 @@ pcap_trace_command_internal (vlib_main_t * vm,
   return 0;
 }
 
-static clib_error_t *
-pcap_rx_trace_command_fn (vlib_main_t * vm,
-			  unformat_input_t * input, vlib_cli_command_t * cmd)
-{
-  return pcap_trace_command_internal (vm, input, cmd, VLIB_RX);
-}
-
-static clib_error_t *
-pcap_tx_trace_command_fn (vlib_main_t * vm,
-			  unformat_input_t * input, vlib_cli_command_t * cmd)
-{
-  return pcap_trace_command_internal (vm, input, cmd, VLIB_TX);
-}
-
-
 /*?
  * This command is used to start or stop a packet capture, or show
- * the status of packet capture. Note that both "pcap rx trace" and
- * "pcap tx trace" are implemented. The command syntax is identical,
- * simply substitute rx for tx as needed.
+ * the status of packet capture.
  *
  * This command has the following optional parameters:
  *
- * - <b>on|off</b> - Used to start or stop a packet capture.
+ *
+ * - <b>rx</b> - Capture received packets
+ *
+ * - <b>tx</b> - Capture transmitted packets
+ *
+ * - <b>drop</b> - Capture dropped packets
+ *
+ * - <b>off</b> - Stop capturing packets, write results to the specified file
  *
  * - <b>max <nn></b> - Depth of local buffer. Once '<em>nn</em>' number
  *   of packets have been received, buffer is flushed to file. Once another
@@ -1922,7 +1980,10 @@ pcap_tx_trace_command_fn (vlib_main_t * vm,
  *   to file, overwriting previous write. If not entered, value defaults
  *   to 100. Can only be updated if packet capture is off.
  *
- * - <b>intfc <interface>|any</b> - Used to specify a given interface,
+ * - <b>max-bytes-per-pkt <nnnn></b> - Maximum number of bytes to capture
+ *   for each packet. Must be >= 32, <= 9000.
+ *
+ * - <b>intfc <interface-name>|any</b> - Used to specify a given interface,
  *   or use '<em>any</em>' to run packet capture on all interfaces.
  *   '<em>any</em>' is the default if not provided. Settings from a previous
  *   packet capture are preserved, so '<em>any</em>' can be used to reset
@@ -1931,8 +1992,9 @@ pcap_tx_trace_command_fn (vlib_main_t * vm,
  * - <b>file <name></b> - Used to specify the output filename. The file will
  *   be placed in the '<em>/tmp</em>' directory, so only the filename is
  *   supported. Directory should not be entered. If file already exists, file
- *   will be overwritten. If no filename is provided, '<em>/tmp/vpe.pcap</em>'
- *   will be used. Can only be updated if packet capture is off.
+ *   will be overwritten. If no filename is provided, the file will be
+ *   named "/tmp/rx.pcap", "/tmp/tx.pcap", "/tmp/rxandtx.pcap", etc.
+ *   Can only be updated if packet capture is off.
  *
  * - <b>status</b> - Displays the current status and configured attributes
  *   associated with a packet capture. If packet capture is in progress,
@@ -1942,21 +2004,20 @@ pcap_tx_trace_command_fn (vlib_main_t * vm,
  *
  * @cliexpar
  * Example of how to display the status of a tx packet capture when off:
- * @cliexstart{pcap tx trace status}
+ * @cliexstart{pcap trace status}
  * max is 100, for any interface to file /tmp/vpe.pcap
  * pcap tx capture is off...
  * @cliexend
  * Example of how to start a tx packet capture:
- * @cliexstart{pcap tx trace on max 35 intfc GigabitEthernet0/8/0 file vppTest.pcap}
- * pcap tx capture on...
+ * @cliexstart{pcap trace tx max 35 intfc GigabitEthernet0/8/0 file vppTest.pcap}
  * @cliexend
  * Example of how to display the status of a tx packet capture in progress:
- * @cliexstart{pcap tx trace status}
+ * @cliexstart{pcap trace status}
  * max is 35, for interface GigabitEthernet0/8/0 to file /tmp/vppTest.pcap
  * pcap tx capture is on: 20 of 35 pkts...
  * @cliexend
  * Example of how to stop a tx packet capture:
- * @cliexstart{vppctl pcap tx trace off}
+ * @cliexstart{pcap trace off}
  * captured 21 pkts...
  * saved to /tmp/vppTest.pcap...
  * @cliexend
@@ -1964,16 +2025,10 @@ pcap_tx_trace_command_fn (vlib_main_t * vm,
 /* *INDENT-OFF* */
 
 VLIB_CLI_COMMAND (pcap_tx_trace_command, static) = {
-    .path = "pcap tx trace",
-    .short_help =
-    "pcap tx trace [on|off] [max <nn>] [intfc <interface>|any] [file <name>] [status]",
-    .function = pcap_tx_trace_command_fn,
-};
-VLIB_CLI_COMMAND (pcap_rx_trace_command, static) = {
-    .path = "pcap rx trace",
+    .path = "pcap trace",
     .short_help =
-    "pcap rx trace [on|off] [max <nn>] [intfc <interface>|any] [file <name>] [status]",
-    .function = pcap_rx_trace_command_fn,
+    "pcap trace rx tx drop off [max <nn>] [intfc <interface>|any] [file <name>] [status] [max-bytes-per-pkt <nnnn>]",
+    .function = pcap_trace_command_fn,
 };
 /* *INDENT-ON* */
 
diff --git a/src/vnet/interface_output.c b/src/vnet/interface_output.c
index 721236a777f..8eb2e67b1bd 100644
--- a/src/vnet/interface_output.c
+++ b/src/vnet/interface_output.c
@@ -802,8 +802,10 @@ static_always_inline void vnet_interface_pcap_tx_trace
 {
   u32 n_left_from, *from;
   u32 sw_if_index;
+  vnet_main_t *vnm;
+  vnet_pcap_t *pp = &vlib_global_main.pcap;
 
-  if (PREDICT_TRUE (vlib_global_main.pcap[VLIB_TX].pcap_enable == 0))
+  if (PREDICT_TRUE (pp->pcap_tx_enable == 0))
     return;
 
   if (sw_if_index_from_buffer == 0)
@@ -814,7 +816,7 @@ static_always_inline void vnet_interface_pcap_tx_trace
   else
     sw_if_index = ~0;
 
-  vnet_main_t *vnm = vnet_get_main ();
+  vnm = vnet_get_main ();
   n_left_from = frame->n_vectors;
   from = vlib_frame_vector_args (frame);
 
@@ -833,18 +835,15 @@ static_always_inline void vnet_interface_pcap_tx_trace
 	    (b0, vnm->classify_filter_table_indices[0],
 	     0 /* full classify */ );
 	  if (classify_filter_result)
-	    pcap_add_buffer (&vlib_global_main.pcap[VLIB_TX].pcap_main, vm,
-			     bi0, 512);
+	    pcap_add_buffer (&pp->pcap_main, vm, bi0, pp->max_bytes_per_pkt);
 	  continue;
 	}
 
       if (sw_if_index_from_buffer)
 	sw_if_index = vnet_buffer (b0)->sw_if_index[VLIB_TX];
 
-      if (vlib_global_main.pcap[VLIB_TX].pcap_sw_if_index == 0 ||
-	  vlib_global_main.pcap[VLIB_TX].pcap_sw_if_index == sw_if_index)
-	pcap_add_buffer (&vlib_global_main.pcap[VLIB_TX].pcap_main, vm, bi0,
-			 512);
+      if (pp->pcap_sw_if_index == 0 || pp->pcap_sw_if_index == sw_if_index)
+	pcap_add_buffer (&pp->pcap_main, vm, bi0, pp->max_bytes_per_pkt);
     }
 }
 
@@ -1169,7 +1168,8 @@ interface_drop_punt (vlib_main_t * vm,
 
 static inline void
 pcap_drop_trace (vlib_main_t * vm,
-		 vnet_interface_main_t * im, vlib_frame_t * f)
+		 vnet_interface_main_t * im,
+		 vnet_pcap_t * pp, vlib_frame_t * f)
 {
   u32 *from;
   u32 n_left = f->n_vectors;
@@ -1199,8 +1199,8 @@ pcap_drop_trace (vlib_main_t * vm,
 	continue;
 
       /* Trace all drops, or drops received on a specific interface */
-      if (im->pcap_sw_if_index == 0 ||
-	  im->pcap_sw_if_index == vnet_buffer (b0)->sw_if_index[VLIB_RX])
+      if (pp->pcap_sw_if_index == 0 ||
+	  pp->pcap_sw_if_index == vnet_buffer (b0)->sw_if_index[VLIB_RX])
 	{
 	  save_current_data = b0->current_data;
 	  save_current_length = b0->current_length;
@@ -1222,7 +1222,7 @@ pcap_drop_trace (vlib_main_t * vm,
 	  else if (b0->current_data > 0)
 	    vlib_buffer_advance (b0, (word) - b0->current_data);
 
-	  pcap_add_buffer (&im->pcap_main, vm, bi0, 512);
+	  pcap_add_buffer (&pp->pcap_main, vm, bi0, pp->max_bytes_per_pkt);
 
 	  b0->current_data = save_current_data;
 	  b0->current_length = save_current_length;
@@ -1251,9 +1251,10 @@ VLIB_NODE_FN (interface_drop) (vlib_main_t * vm,
 			       vlib_frame_t * frame)
 {
   vnet_interface_main_t *im = &vnet_get_main ()->interface_main;
+  vnet_pcap_t *pp = &vlib_global_main.pcap;
 
-  if (PREDICT_FALSE (im->drop_pcap_enable))
-    pcap_drop_trace (vm, im, frame);
+  if (PREDICT_FALSE (pp->pcap_drop_enable))
+    pcap_drop_trace (vm, im, pp, frame);
 
   return interface_drop_punt (vm, node, frame, VNET_ERROR_DISPOSITION_DROP);
 }
@@ -1416,142 +1417,6 @@ vnet_set_interface_output_node (vnet_main_t * vnm,
 }
 #endif /* CLIB_MARCH_VARIANT */
 
-static clib_error_t *
-pcap_drop_trace_command_fn (vlib_main_t * vm,
-			    unformat_input_t * input,
-			    vlib_cli_command_t * cmd)
-{
-  vnet_main_t *vnm = vnet_get_main ();
-  vnet_interface_main_t *im = &vnm->interface_main;
-  u8 *filename;
-  u32 max;
-  int matched = 0;
-  clib_error_t *error = 0;
-
-  while (unformat_check_input (input) != UNFORMAT_END_OF_INPUT)
-    {
-      if (unformat (input, "on"))
-	{
-	  if (im->drop_pcap_enable == 0)
-	    {
-	      if (im->pcap_filename == 0)
-		im->pcap_filename = format (0, "/tmp/drop.pcap%c", 0);
-
-	      clib_memset (&im->pcap_main, 0, sizeof (im->pcap_main));
-	      im->pcap_main.file_name = (char *) im->pcap_filename;
-	      im->pcap_main.n_packets_to_capture = PCAP_DEF_PKT_TO_CAPTURE;
-	      if (im->pcap_pkts_to_capture)
-		im->pcap_main.n_packets_to_capture = im->pcap_pkts_to_capture;
-
-	      im->pcap_main.packet_type = PCAP_PACKET_TYPE_ethernet;
-	      im->drop_pcap_enable = 1;
-	      matched = 1;
-	      vlib_cli_output (vm, "pcap drop capture on...");
-	    }
-	  else
-	    {
-	      vlib_cli_output (vm, "pcap drop capture already on...");
-	    }
-	  matched = 1;
-	}
-      else if (unformat (input, "off"))
-	{
-	  matched = 1;
-
-	  if (im->drop_pcap_enable)
-	    {
-	      vlib_cli_output (vm, "captured %d pkts...",
-			       im->pcap_main.n_packets_captured);
-	      if (im->pcap_main.n_packets_captured)
-		{
-		  im->pcap_main.n_packets_to_capture =
-		    im->pcap_main.n_packets_captured;
-		  error = pcap_write (&im->pcap_main);
-		  if (im->pcap_main.flags & PCAP_MAIN_INIT_DONE)
-		    pcap_close (&im->pcap_main);
-		  if (error)
-		    clib_error_report (error);
-		  else
-		    vlib_cli_output (vm, "saved to %s...", im->pcap_filename);
-		}
-	    }
-	  else
-	    {
-	      vlib_cli_output (vm, "pcap drop capture already off...");
-	    }
-
-	  im->drop_pcap_enable = 0;
-	}
-      else if (unformat (input, "max %d", &max))
-	{
-	  im->pcap_pkts_to_capture = max;
-	  matched = 1;
-	}
-
-      else if (unformat (input, "intfc %U",
-			 unformat_vnet_sw_interface, vnm,
-			 &im->pcap_sw_if_index))
-	matched = 1;
-      else if (unformat (input, "intfc any"))
-	{
-	  im->pcap_sw_if_index = 0;
-	  matched = 1;
-	}
-      else if (unformat (input, "file %s", &filename))
-	{
-	  u8 *chroot_filename;
-	  /* Brain-police user path input */
-	  if (strstr ((char *) filename, "..")
-	      || index ((char *) filename, '/'))
-	    {
-	      vlib_cli_output (vm, "illegal characters in filename '%s'",
-			       filename);
-	      continue;
-	    }
-
-	  chroot_filename = format (0, "/tmp/%s%c", filename, 0);
-	  vec_free (filename);
-
-	  if (im->pcap_filename)
-	    vec_free (im->pcap_filename);
-	  im->pcap_filename = chroot_filename;
-	  im->pcap_main.file_name = (char *) im->pcap_filename;
-	  matched = 1;
-	}
-      else if (unformat (input, "status"))
-	{
-	  if (im->drop_pcap_enable == 0)
-	    {
-	      vlib_cli_output (vm, "pcap drop capture is off...");
-	      continue;
-	    }
-
-	  vlib_cli_output (vm, "pcap drop capture: %d of %d pkts...",
-			   im->pcap_main.n_packets_captured,
-			   im->pcap_main.n_packets_to_capture);
-	  matched = 1;
-	}
-
-      else
-	break;
-    }
-
-  if (matched == 0)
-    return clib_error_return (0, "unknown input `%U'",
-			      format_unformat_error, input);
-
-  return 0;
-}
-
-/* *INDENT-OFF* */
-VLIB_CLI_COMMAND (pcap_trace_command, static) = {
-  .path = "pcap drop trace",
-  .short_help =
-  "pcap drop trace on off max <nn> intfc <intfc> file <name> status",
-  .function = pcap_drop_trace_command_fn,
-};
-/* *INDENT-ON* */
-
 /*
  * fd.io coding-style-patch-verification: ON
  *