[dpdk-dev] [PATCH v2] net/pcap: support snaplen option to truncate packet

[Zhike Wang]

Introduced "snaplen=<length>" option. It is convenient to truncate
large packets to only capture necessary headers.

Signed-off-by: Zhike Wang <wangzhike at jd.com>
---
 app/pdump/main.c                | 32 +++++++++++++++++++++++++++++++-
 drivers/net/pcap/rte_eth_pcap.c | 35 ++++++++++++++++++++++++++++++++++-
 2 files changed, 65 insertions(+), 2 deletions(-)

diff --git a/app/pdump/main.c b/app/pdump/main.c
index c38c537..241346b 100644
--- a/app/pdump/main.c
+++ b/app/pdump/main.c
@@ -41,10 +41,12 @@
 #define PDUMP_RING_SIZE_ARG "ring-size"
 #define PDUMP_MSIZE_ARG "mbuf-size"
 #define PDUMP_NUM_MBUFS_ARG "total-num-mbufs"
+#define PDUMP_SNAPLEN_ARG "snaplen"
 
 #define VDEV_NAME_FMT "net_pcap_%s_%d"
 #define VDEV_PCAP_ARGS_FMT "tx_pcap=%s"
 #define VDEV_IFACE_ARGS_FMT "tx_iface=%s"
+#define VDEV_SNAPLEN_ARGS_FMT "snaplen=%d"
 #define TX_STREAM_SIZE 64
 
 #define MP_NAME "pdump_pool_%d"
@@ -97,6 +99,7 @@ enum pdump_by {
 	PDUMP_RING_SIZE_ARG,
 	PDUMP_MSIZE_ARG,
 	PDUMP_NUM_MBUFS_ARG,
+	PDUMP_SNAPLEN_ARG,
 	NULL
 };
 
@@ -116,6 +119,7 @@ struct pdump_tuples {
 	uint32_t ring_size;
 	uint16_t mbuf_data_size;
 	uint32_t total_num_mbufs;
+	uint16_t snaplen;
 
 	/* params for library API call */
 	uint32_t dir;
@@ -160,7 +164,8 @@ struct parse_val {
 			" tx-dev=<iface or pcap file>,"
 			"[ring-size=<ring size>default:16384],"
 			"[mbuf-size=<mbuf data size>default:2176],"
-			"[total-num-mbufs=<number of mbufs>default:65535]'\n",
+			"[total-num-mbufs=<number of mbufs>default:65535],",
+			"[snaplen=<snap length>default:0, meaning no truncation]'\n",
 			prgname);
 }
 
@@ -370,6 +375,19 @@ struct parse_val {
 	} else
 		pt->total_num_mbufs = MBUFS_PER_POOL;
 
+	/* snaplen parsing and validation */
+	cnt1 = rte_kvargs_count(kvlist, PDUMP_SNAPLEN_ARG);
+	if (cnt1 == 1) {
+		v.min = 1;
+		v.max = UINT16_MAX;
+		ret = rte_kvargs_process(kvlist, PDUMP_SNAPLEN_ARG,
+						&parse_uint_value, &v);
+		if (ret < 0)
+			goto free_kvlist;
+		pt->snaplen = (uint16_t) v.val;
+	} else
+		pt->snaplen = 0;
+
 	num_tuples++;
 
 free_kvlist:
@@ -692,6 +710,9 @@ struct parse_val {
 				 VDEV_IFACE_ARGS_FMT, pt->rx_dev) :
 			snprintf(vdev_args, sizeof(vdev_args),
 				 VDEV_PCAP_ARGS_FMT, pt->rx_dev);
+			snprintf(vdev_args + strlen(vdev_args),
+				 sizeof(vdev_args) - strlen(vdev_args),
+				 ","VDEV_SNAPLEN_ARGS_FMT, pt->snaplen);
 			if (rte_eal_hotplug_add("vdev", vdev_name,
 						vdev_args) < 0) {
 				cleanup_rings();
@@ -722,6 +743,9 @@ struct parse_val {
 					 VDEV_IFACE_ARGS_FMT, pt->tx_dev) :
 				snprintf(vdev_args, sizeof(vdev_args),
 					 VDEV_PCAP_ARGS_FMT, pt->tx_dev);
+				snprintf(vdev_args + strlen(vdev_args),
+					 sizeof(vdev_args) - strlen(vdev_args),
+					 ","VDEV_SNAPLEN_ARGS_FMT, pt->snaplen);
 				if (rte_eal_hotplug_add("vdev", vdev_name,
 							vdev_args) < 0) {
 					cleanup_rings();
@@ -762,6 +786,9 @@ struct parse_val {
 				 VDEV_IFACE_ARGS_FMT, pt->rx_dev) :
 			snprintf(vdev_args, sizeof(vdev_args),
 				 VDEV_PCAP_ARGS_FMT, pt->rx_dev);
+			snprintf(vdev_args + strlen(vdev_args),
+				 sizeof(vdev_args) - strlen(vdev_args),
+				 ","VDEV_SNAPLEN_ARGS_FMT, pt->snaplen);
 			if (rte_eal_hotplug_add("vdev", vdev_name,
 						vdev_args) < 0) {
 				cleanup_rings();
@@ -799,6 +826,9 @@ struct parse_val {
 				 VDEV_IFACE_ARGS_FMT, pt->tx_dev) :
 			snprintf(vdev_args, sizeof(vdev_args),
 				 VDEV_PCAP_ARGS_FMT, pt->tx_dev);
+			snprintf(vdev_args + strlen(vdev_args),
+				 sizeof(vdev_args) - strlen(vdev_args),
+				 ","VDEV_SNAPLEN_ARGS_FMT, pt->snaplen);
 			if (rte_eal_hotplug_add("vdev", vdev_name,
 						vdev_args) < 0) {
 				cleanup_rings();
diff --git a/drivers/net/pcap/rte_eth_pcap.c b/drivers/net/pcap/rte_eth_pcap.c
index 13a3d0a..d51ea48 100644
--- a/drivers/net/pcap/rte_eth_pcap.c
+++ b/drivers/net/pcap/rte_eth_pcap.c
@@ -40,6 +40,7 @@
 #define ETH_PCAP_IFACE_ARG    "iface"
 #define ETH_PCAP_PHY_MAC_ARG  "phy_mac"
 #define ETH_PCAP_INFINITE_RX_ARG  "infinite_rx"
+#define ETH_PCAP_SNAPLEN_ARG  "snaplen"
 
 #define ETH_PCAP_ARG_MAXLEN	64
 
@@ -92,6 +93,7 @@ struct pmd_process_private {
 	pcap_t *rx_pcap[RTE_PMD_PCAP_MAX_QUEUES];
 	pcap_t *tx_pcap[RTE_PMD_PCAP_MAX_QUEUES];
 	pcap_dumper_t *tx_dumper[RTE_PMD_PCAP_MAX_QUEUES];
+	int snaplen;
 };
 
 struct pmd_devargs {
@@ -114,6 +116,7 @@ struct pmd_devargs_all {
 	unsigned int is_rx_pcap;
 	unsigned int is_rx_iface;
 	unsigned int infinite_rx;
+	int snaplen;
 };
 
 static const char *valid_arguments[] = {
@@ -125,6 +128,7 @@ struct pmd_devargs_all {
 	ETH_PCAP_IFACE_ARG,
 	ETH_PCAP_PHY_MAC_ARG,
 	ETH_PCAP_INFINITE_RX_ARG,
+	ETH_PCAP_SNAPLEN_ARG,
 	NULL
 };
 
@@ -339,6 +343,9 @@ struct pmd_devargs_all {
 			caplen = sizeof(temp_data);
 		}
 
+		if ((pp->snaplen > 0) && (caplen > pp->snaplen))
+			caplen = pp->snaplen;
+
 		calculate_timestamp(&header.ts);
 		header.len = len;
 		header.caplen = caplen;
@@ -949,6 +956,7 @@ struct pmd_devargs_all {
 {
 	const char *pcap_filename = value;
 	struct pmd_devargs *dumpers = extra_args;
+	int snaplen;
 	pcap_dumper_t *dumper;
 
 	if (open_single_tx_pcap(pcap_filename, &dumper) < 0)
@@ -1083,6 +1091,19 @@ struct pmd_devargs_all {
 }
 
 static int
+get_snaplen_arg(const char *key __rte_unused,
+		const char *value, void *extra_args)
+{
+	if (extra_args) {
+		const int snaplen = atoi(value);
+		int *snaplen_p = extra_args;
+
+		*snaplen_p = snaplen;
+	}
+	return 0;
+}
+
+static int
 pmd_init_internals(struct rte_vdev_device *vdev,
 		const unsigned int nb_rx_queues,
 		const unsigned int nb_tx_queues,
@@ -1335,6 +1356,7 @@ struct pmd_devargs_all {
 	struct rte_eth_dev *eth_dev =  NULL;
 	struct pmd_internals *internal;
 	int ret = 0;
+	unsigned int snaplen_cnt;
 
 	struct pmd_devargs_all devargs_all = {
 		.single_iface = 0,
@@ -1412,6 +1434,15 @@ struct pmd_devargs_all {
 		rte_kvargs_count(kvlist, ETH_PCAP_TX_IFACE_ARG) ? 1 : 0;
 	dumpers.num_of_queue = 0;
 
+	snaplen_cnt = rte_kvargs_count(kvlist,
+				ETH_PCAP_SNAPLEN_ARG);
+	if (snaplen_cnt == 1) {
+		ret = rte_kvargs_process(kvlist, ETH_PCAP_SNAPLEN_ARG,
+				&get_snaplen_arg, &devargs_all.snaplen);
+		if (ret < 0)
+			goto free_kvlist;
+	}
+
 	if (devargs_all.is_rx_pcap) {
 		/*
 		 * We check whether we want to infinitely rx the pcap file.
@@ -1518,6 +1549,7 @@ struct pmd_devargs_all {
 			pp->tx_pcap[i] = dumpers.queue[i].pcap;
 		}
 
+		pp->snaplen = devargs_all.snaplen;
 		eth_dev->process_private = pp;
 		eth_dev->rx_pkt_burst = eth_pcap_rx;
 		if (devargs_all.is_tx_pcap)
@@ -1587,7 +1619,8 @@ struct pmd_devargs_all {
 	ETH_PCAP_TX_IFACE_ARG "=<ifc> "
 	ETH_PCAP_IFACE_ARG "=<ifc> "
 	ETH_PCAP_PHY_MAC_ARG "=<int>"
-	ETH_PCAP_INFINITE_RX_ARG "=<0|1>");
+	ETH_PCAP_INFINITE_RX_ARG "=<0|1>"
+	ETH_PCAP_SNAPLEN_ARG "=<int>");
 
 RTE_INIT(eth_pcap_init_log)
 {
-- 
1.8.3.1