pg: set vnet buffer flags in pg streams

See .../extras/pg/checksum_offload.pg for a nontrivial example, which
deliberately sets bogus ip and udp checksums in the generated packets,
then fixes the mess with (software emulated) hardware checksum
offload.

Validated via "pcap dispatch trace on max 1000 buffer-trace pg-input 100".
Packets stuffed into loop1-output have the configured bogus ip and udp
checksums. vnet_calc_checksums_inline(...) fixes the checksums, which
are correct when packets visit loop1-tx.

The packet generator is a dumb robot in this regard. If you ask for a
ridiculous flag combination - example: ip4 and ip6 - your mileage may
vary.

Type: feature

Signed-off-by: Dave Barach <dave@barachs.net>
Change-Id: I6d9e790f373bcd9e445a89113ca8e4c8f9aa9419

extras/pg/checksum_offload.pg

@@ -0,0 +1,26 @@
+set term pag off
+loop cre
+set int ip address loop0 11.22.33.1/24
+set int state loop0 up
+loop cre
+set int ip address loop1 11.22.34.1/24
+set int state loop1 up
+
+set ip neighbor loop1 11.22.34.44 03:00:11:22:34:44
+
+packet-generator new {
+    name s0
+    limit 10000
+    size 128-128
+    interface loop0
+    tx-interface loop1
+    node loop1-output
+    buffer-flags ip4 offload-ip-cksum offload-udp-cksum
+    data { IP4: 1.2.3 -> 4.5.6
+           UDP: 11.22.33.44 -> 11.22.34.44
+                ttl 2 checksum 13
+           UDP: 1234 -> 2345
+                checksum 11
+           incrementing 114
+    }
+}

extras/pg/ip6_simple.pg

@@ -0,0 +1,12 @@
+
+packet-generator new {
+    name x
+    limit 5
+    size 128-128
+    interface local0
+    node ip6-lookup
+    data {
+        ICMP: db00::1 -> db00::2
+        incrementing 30
+    }
+}

src/vnet/interface_format.c

@@ -670,6 +670,34 @@ vnet_register_format_buffer_opaque2_helper (vnet_buffer_opquae_formatter_t fp)
 }
 
 
+uword
+unformat_vnet_buffer_flags (unformat_input_t * input, va_list * args)
+{
+  u32 *flagp = va_arg (*args, u32 *);
+  int rv = 0;
+  u32 flags = 0;
+
+  while (unformat_check_input (input) != UNFORMAT_END_OF_INPUT)
+    {
+      /* Red herring, there is no such buffer flag */
+      if (unformat (input, "avail8"))
+	return 0;
+#define _(bit,enum,str,verbose)                                 \
+      else if (unformat (input, str))                           \
+        {                                                       \
+          flags |= (1 << LOG2_VLIB_BUFFER_FLAG_USER(bit));      \
+          rv = 1;                                               \
+        }
+      foreach_vnet_buffer_flag
+#undef _
+	else
+	break;
+    }
+  if (rv)
+    *flagp = flags;
+  return rv;
+}
+
 uword
 unformat_vnet_hw_interface (unformat_input_t * input, va_list * args)
 {

src/vnet/interface_funcs.h

@@ -444,6 +444,7 @@ format_function_t format_vnet_sw_interface_flags;
 /* Parses sw/hw interface name -> index. */
 unformat_function_t unformat_vnet_sw_interface;
 unformat_function_t unformat_vnet_hw_interface;
+unformat_function_t unformat_vnet_buffer_flags;
 
 /* Parses interface flags (up, down, enable, disable, etc.) */
 unformat_function_t unformat_vnet_hw_interface_flags;

src/vnet/pg/cli.c

@@ -376,6 +376,10 @@ new_stream (vlib_main_t * vm,
       else if (unformat (input, "source pg%u", &s.if_id))
 	;
 
+      else if (unformat (input, "buffer-flags %U",
+			 unformat_vnet_buffer_flags, &s.buffer_flags))
+	;
+
       else if (unformat (input, "node %U",
 			 unformat_vlib_node, vm, &s.node_index))
 	;

src/vnet/pg/input.c

@@ -1106,6 +1106,8 @@ init_buffers_inline (vlib_main_t * vm,
 
       b0 = vlib_get_buffer (vm, bi0);
       b1 = vlib_get_buffer (vm, bi1);
+      b0->flags |= s->buffer_flags;
+      b1->flags |= s->buffer_flags;
 
       vnet_buffer (b0)->sw_if_index[VLIB_RX] =
 	vnet_buffer (b1)->sw_if_index[VLIB_RX] = s->sw_if_index[VLIB_RX];
@@ -1135,6 +1137,7 @@ init_buffers_inline (vlib_main_t * vm,
       n_left -= 1;
 
       b0 = vlib_get_buffer (vm, bi0);
+      b0->flags |= s->buffer_flags;
       vnet_buffer (b0)->sw_if_index[VLIB_RX] = s->sw_if_index[VLIB_RX];
       vnet_buffer (b0)->sw_if_index[VLIB_TX] = s->sw_if_index[VLIB_TX];
 
@@ -1269,7 +1272,7 @@ pg_stream_fill_replay (pg_main_t * pg, pg_stream_t * s, u32 n_alloc)
 	  clib_memcpy_fast (b->data, d0 + data_offset, bytes_this_chunk);
 	  vnet_buffer (b)->sw_if_index[VLIB_RX] = s->sw_if_index[VLIB_RX];
 	  vnet_buffer (b)->sw_if_index[VLIB_TX] = s->sw_if_index[VLIB_TX];
-	  b->flags = 0;
+	  b->flags = s->buffer_flags;
 	  b->next_buffer = 0;
 	  b->current_data = 0;
 	  b->current_length = bytes_this_chunk;

src/vnet/pg/pg.h

@@ -123,6 +123,9 @@ typedef struct pg_stream_t
      for max_packet_bytes. */
   u32 buffer_bytes;
 
+  /* Buffer flags to set in each packet e.g. checksum offload flags */
+  u32 buffer_flags;
+
   /* Last packet length if packet size edit type is increment. */
   u32 last_increment_packet_size;