Add "setcounter" and "getcounter" messages, providing the the ability

to embed up to four counters in outgoing packets.  The message specifies
the offset at which the counter should be inserted as well as the
parameters of the counter.

Example usage:

  ngctl msg src0: setcounter \
    '{ index=0 offset=0x40 flags=1 width=4 increment=1 max_val=12345 }'

Sponsored by:   Sandvine Incorporated

sys/netgraph/ng_source.c

@@ -86,11 +86,13 @@ struct privdata {
 	hook_p				output;
 	struct ng_source_stats		stats;
 	struct ifqueue			snd_queue;	/* packets to send */
+	struct mbuf			*last_packet;	/* last pkt in queue */
 	struct ifnet			*output_ifp;
 	struct callout			intr_ch;
 	uint64_t			packets;	/* packets to send */
 	uint32_t			queueOctets;
 	struct ng_source_embed_info	embed_timestamp;
+	struct ng_source_embed_cnt_info	embed_counter[NG_SOURCE_COUNTERS];
 };
 typedef struct privdata *sc_p;
 
@@ -115,6 +117,9 @@ static int		ng_source_send (sc_p, int, int *);
 static int		ng_source_store_output_ifp(sc_p, char *);
 static void		ng_source_packet_mod(sc_p, struct mbuf *,
 			    int, int, caddr_t, int);
+static void		ng_source_mod_counter(sc_p sc,
+			    struct ng_source_embed_cnt_info *cnt,
+			    struct mbuf *m, int increment);
 static int		ng_source_dup_mod(sc_p, struct mbuf *,
 			    struct mbuf **);
 
@@ -145,6 +150,14 @@ static const struct ng_parse_type ng_source_embed_type = {
 	&ng_source_embed_type_fields
 };
 
+/* Parse type for struct ng_source_embed_cnt_info */
+static const struct ng_parse_struct_field ng_source_embed_cnt_type_fields[] =
+	NG_SOURCE_EMBED_CNT_TYPE_INFO;
+static const struct ng_parse_type ng_source_embed_cnt_type = {
+	&ng_parse_struct_type,
+	&ng_source_embed_cnt_type_fields
+};
+
 /* List of commands and how to convert arguments to/from ASCII */
 static const struct ng_cmdlist ng_source_cmds[] = {
 	{
@@ -217,6 +230,20 @@ static const struct ng_cmdlist ng_source_cmds[] = {
 	  NULL,
 	  &ng_source_embed_type
 	},
+	{
+	  NGM_SOURCE_COOKIE,
+	  NGM_SOURCE_SET_COUNTER,
+	  "setcounter",
+	  &ng_source_embed_cnt_type,
+	  NULL
+	},
+	{
+	  NGM_SOURCE_COOKIE,
+	  NGM_SOURCE_GET_COUNTER,
+	  "getcounter",
+	  &ng_parse_uint8_type,
+	  &ng_source_embed_cnt_type
+	},
 	{ 0 }
 };
 
@@ -424,6 +451,41 @@ ng_source_rcvmsg(node_p node, item_p item, hook_p lasthook)
 			embed = (struct ng_source_embed_info *)resp->data;
 			bcopy(&sc->embed_timestamp, embed, sizeof(*embed));
 
+			break;
+		    }
+		case NGM_SOURCE_SET_COUNTER:
+		    {
+			struct ng_source_embed_cnt_info *embed;
+
+			embed = (struct ng_source_embed_cnt_info *)msg->data;
+			if (embed->index >= NG_SOURCE_COUNTERS ||
+			    !(embed->width == 1 || embed->width == 2 ||
+			    embed->width == 4)) {
+				error = EINVAL;
+				goto done;
+			}
+			bcopy(embed, &sc->embed_counter[embed->index],
+			    sizeof(*embed));
+
+			break;
+		    }
+		case NGM_SOURCE_GET_COUNTER:
+		    {
+			uint8_t index = *(uint8_t *)msg->data;
+			struct ng_source_embed_cnt_info *embed;
+
+			if (index >= NG_SOURCE_COUNTERS) {
+				error = EINVAL;
+				goto done;
+			}
+			NG_MKRESPONSE(resp, msg, sizeof(*embed), M_DONTWAIT);
+			if (resp == NULL) {
+				error = ENOMEM;
+				goto done;
+			}
+			embed = (struct ng_source_embed_cnt_info *)resp->data;
+			bcopy(&sc->embed_counter[index], embed, sizeof(*embed));
+
 			break;
 		    }
 		default:
@@ -495,6 +557,7 @@ ng_source_rcvdata(hook_p hook, item_p item)
 	/* XXX should we check IF_QFULL() ? */
 	_IF_ENQUEUE(&sc->snd_queue, m);
 	sc->queueOctets += m->m_pkthdr.len;
+	sc->last_packet = m;
 
 	return (0);
 }
@@ -600,6 +663,7 @@ ng_source_clr_data (sc_p sc)
 		NG_FREE_M(m);
 	}
 	sc->queueOctets = 0;
+	sc->last_packet = 0;
 }
 
 /*
@@ -761,16 +825,48 @@ ng_source_packet_mod(sc_p sc, struct mbuf *m, int offset, int len, caddr_t cp,
 	bcopy(cp, mtod_off(m, offset, caddr_t), len);
 }
 
+static void
+ng_source_mod_counter(sc_p sc, struct ng_source_embed_cnt_info *cnt,
+    struct mbuf *m, int increment)
+{
+	caddr_t cp;
+	uint32_t val;
+
+	val = htonl(cnt->next_val);
+	cp = (caddr_t)&val + sizeof(val) - cnt->width;
+	ng_source_packet_mod(sc, m, cnt->offset, cnt->width, cp, cnt->flags);
+
+	if (increment) {
+		cnt->next_val += increment;
+
+		if (increment > 0 && cnt->next_val > cnt->max_val) {
+			cnt->next_val = cnt->min_val - 1 +
+			    (cnt->next_val - cnt->max_val);
+			if (cnt->next_val > cnt->max_val)
+				cnt->next_val = cnt->max_val;
+		} else if (increment < 0 && cnt->next_val < cnt->min_val) {
+			cnt->next_val = cnt->max_val + 1 +
+			    (cnt->next_val - cnt->min_val);
+			if (cnt->next_val < cnt->min_val)
+				cnt->next_val = cnt->max_val;
+		}
+	}
+}
+
 static int
 ng_source_dup_mod(sc_p sc, struct mbuf *m0, struct mbuf **m_ptr)
 {
 	struct mbuf *m;
+	struct ng_source_embed_cnt_info *cnt;
 	struct ng_source_embed_info *ts;
 	int modify;
 	int error = 0;
+	int i, increment;
 
 	/* Are we going to modify packets? */
 	modify = sc->embed_timestamp.flags & NGM_SOURCE_EMBED_ENABLE;
+	for (i = 0; !modify && i < NG_SOURCE_COUNTERS; ++i)
+		modify = sc->embed_counter[i].flags & NGM_SOURCE_EMBED_ENABLE;
 
 	/* Duplicate the packet. */
 	if (modify)
@@ -789,6 +885,18 @@ ng_source_dup_mod(sc_p sc, struct mbuf *m0, struct mbuf **m_ptr)
 	/* Modify the copied packet for sending. */
 	KASSERT(M_WRITABLE(m), ("%s: packet not writable", __func__));
 
+	for (i = 0; i < NG_SOURCE_COUNTERS; ++i) {
+		cnt = &sc->embed_counter[i];
+		if (cnt->flags & NGM_SOURCE_EMBED_ENABLE) {
+			if ((cnt->flags & NGM_SOURCE_INC_CNT_PER_LIST) == 0 ||
+			    sc->last_packet == m0)
+				increment = cnt->increment;
+			else
+				increment = 0;
+			ng_source_mod_counter(sc, cnt, m, increment);
+		}
+	}
+
 	ts = &sc->embed_timestamp;
 	if (ts->flags & NGM_SOURCE_EMBED_ENABLE) {
 		struct timeval now;

sys/netgraph/ng_source.h

@@ -85,6 +85,7 @@ struct ng_source_embed_info {
 	uint8_t		spare;
 };
 #define NGM_SOURCE_EMBED_ENABLE		0x01	/* enable embedding */
+#define	NGM_SOURCE_INC_CNT_PER_LIST	0x02	/* increment once per list */
 
 /* Keep this in sync with the above structure definition. */
 #define NG_SOURCE_EMBED_TYPE_INFO {				\
@@ -93,6 +94,32 @@ struct ng_source_embed_info {
 	{ NULL }						\
 }
 
+/* Packet embedding info for NGM_SOURCE_GET/SET_COUNTER */
+#define	NG_SOURCE_COUNTERS	4
+struct ng_source_embed_cnt_info {
+	uint16_t	offset;		/* offset from ethernet header */
+	uint8_t		flags;		/* as above */
+	uint8_t		width;		/* in bytes (1, 2, 4) */
+	uint32_t	next_val;
+	uint32_t	min_val;
+	uint32_t	max_val;
+	int32_t		increment;
+	uint8_t		index;		/* which counter (0..3) */
+};
+
+/* Keep this in sync with the above structure definition. */
+#define NG_SOURCE_EMBED_CNT_TYPE_INFO {				\
+	{ "offset",		&ng_parse_hint16_type	}, 	\
+	{ "flags",		&ng_parse_hint8_type	},	\
+	{ "width",		&ng_parse_uint8_type	},	\
+	{ "next_val",		&ng_parse_uint32_type	},	\
+	{ "min_val",		&ng_parse_uint32_type	},	\
+	{ "max_val",		&ng_parse_uint32_type	},	\
+	{ "increment",		&ng_parse_int32_type	},	\
+	{ "index",		&ng_parse_uint8_type	},	\
+	{ NULL }						\
+}
+
 /* Netgraph commands */
 enum {
 	NGM_SOURCE_GET_STATS = 1,	/* get stats */
@@ -105,6 +132,8 @@ enum {
 	NGM_SOURCE_SETPPS,		/* rate-limiting packets per second */
 	NGM_SOURCE_SET_TIMESTAMP,	/* embed xmit timestamp */
 	NGM_SOURCE_GET_TIMESTAMP,
+	NGM_SOURCE_SET_COUNTER,		/* embed counter */
+	NGM_SOURCE_GET_COUNTER,
 };
 
 #endif /* _NETGRAPH_NG_SOURCE_H_ */