[dpdk-dev] [PATCH v4] net/pcap: rx_iface_in stream type support

[ido goshen <ido@cgstowernetworks.com>]

From: ido g <ido@cgstowernetworks.com>

Support rx of in direction packets only
Useful for apps that also tx to eth_pcap ports in order to not see them
echoed back in as rx when out direction is also captured

Example:
In case using rx_iface and sending *single* packet to eth1
it will loop forever as the when it is sent to tx_iface=eth1
it will be captured again on the rx_iface=eth1 and so on
  $RTE_TARGET/app/testpmd l 0-3 -n 4 \
	--vdev 'net_pcap0,rx_iface=eth1,tx_iface=eth1'
  …
  ---------------------- Forward statistics for port 0  ------------
  RX-packets: 758            RX-dropped: 0             RX-total: 758
  TX-packets: 758            TX-dropped: 0             TX-total: 758
  ------------------------------------------------------------------
While if using rx_iface_in it will not be captured on the way out and
be forwarded only once
  $RTE_TARGET/app/testpmd l 0-3 -n 4 \
	--vdev 'net_pcap0,rx_iface_in=eth1,tx_iface=eth1'
  …
  ---------------------- Forward statistics for port 0  ------------
  RX-packets: 1              RX-dropped: 0             RX-total: 1
  TX-packets: 1              TX-dropped: 0             TX-total: 1
  ------------------------------------------------------------------

Signed-off-by: ido g <ido@cgstowernetworks.com>
---
v4:
* fix order of rx_face and rx_iface_in mix
* reward pcap_ring doc example
* cosmetics code alignments
* adding example commands in commit log 

v3:
* merge to updated dpdk-next-net code
* pcap_ring doc update

v2:
* clean checkpatch warning

 doc/guides/nics/pcap_ring.rst   | 25 +++++++++++++++++++-
 drivers/net/pcap/rte_eth_pcap.c | 51 +++++++++++++++++++++++++++++++++++++----
 2 files changed, 70 insertions(+), 6 deletions(-)

diff --git a/doc/guides/nics/pcap_ring.rst b/doc/guides/nics/pcap_ring.rst
index 7fd063c..879e543 100644
--- a/doc/guides/nics/pcap_ring.rst
+++ b/doc/guides/nics/pcap_ring.rst
@@ -71,11 +71,19 @@ The different stream types are:
         tx_pcap=/path/to/file.pcap
 
 *   rx_iface: Defines a reception stream based on a network interface name.
-    The driver reads packets coming from the given interface using the Linux kernel driver for that interface.
+    The driver reads packets from the given interface using the Linux kernel driver for that interface.
+    The driver captures both the incoming and outgoing packets on that interface.
     The value is an interface name.
 
         rx_iface=eth0
 
+*   rx_iface_in: Defines a reception stream based on a network interface name.
+    The driver reads packets from the given interface using the Linux kernel driver for that interface.
+    The driver captures only the incoming packets on that interface.
+    The value is an interface name.
+
+        rx_iface_in=eth0
+
 *   tx_iface: Defines a transmission stream based on a network interface name.
     The driver sends packets to the given interface using the Linux kernel driver for that interface.
     The value is an interface name.
@@ -122,6 +130,21 @@ Forward packets through two network interfaces:
     $RTE_TARGET/app/testpmd -l 0-3 -n 4 \
         --vdev 'net_pcap0,iface=eth0' --vdev='net_pcap1;iface=eth1'
 
+Enable 2 tx queues on a network interface:
+
+.. code-block:: console
+
+    $RTE_TARGET/app/testpmd -l 0-3 -n 4 \
+        --vdev 'net_pcap0,rx_iface=eth1,tx_iface=eth1,tx_iface=eth1' \
+        -- --txq 2
+
+Read only incoming packets from a network interface and write them back to the same network interface:
+
+.. code-block:: console
+
+    $RTE_TARGET/app/testpmd -l 0-3 -n 4 \
+        --vdev 'net_pcap0,rx_iface_in=eth1,tx_iface=eth1'
+
 Using libpcap-based PMD with the testpmd Application
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
diff --git a/drivers/net/pcap/rte_eth_pcap.c b/drivers/net/pcap/rte_eth_pcap.c
index b21930b..0a89b24 100644
--- a/drivers/net/pcap/rte_eth_pcap.c
+++ b/drivers/net/pcap/rte_eth_pcap.c
@@ -26,6 +26,7 @@
 #define ETH_PCAP_RX_PCAP_ARG  "rx_pcap"
 #define ETH_PCAP_TX_PCAP_ARG  "tx_pcap"
 #define ETH_PCAP_RX_IFACE_ARG "rx_iface"
+#define ETH_PCAP_RX_IFACE_IN_ARG "rx_iface_in"
 #define ETH_PCAP_TX_IFACE_ARG "tx_iface"
 #define ETH_PCAP_IFACE_ARG    "iface"
 
@@ -83,6 +84,7 @@ struct pmd_devargs {
 	ETH_PCAP_RX_PCAP_ARG,
 	ETH_PCAP_TX_PCAP_ARG,
 	ETH_PCAP_RX_IFACE_ARG,
+	ETH_PCAP_RX_IFACE_IN_ARG,
 	ETH_PCAP_TX_IFACE_ARG,
 	ETH_PCAP_IFACE_ARG,
 	NULL
@@ -739,6 +741,21 @@ struct pmd_devargs {
 }
 
 static inline int
+set_iface_direction(const char *iface, pcap_t *pcap,
+		pcap_direction_t direction)
+{
+	const char *direction_str = (direction == PCAP_D_IN) ? "IN" : "OUT";
+	if (pcap_setdirection(pcap, direction) < 0) {
+		PMD_LOG(ERR, "Setting %s pcap direction %s failed - %s\n",
+				iface, direction_str, pcap_geterr(pcap));
+		return -1;
+	}
+	PMD_LOG(INFO, "Setting %s pcap direction %s\n",
+			iface, direction_str);
+	return 0;
+}
+
+static inline int
 open_iface(const char *key, const char *value, void *extra_args)
 {
 	const char *iface = value;
@@ -761,7 +778,29 @@ struct pmd_devargs {
 static inline int
 open_rx_iface(const char *key, const char *value, void *extra_args)
 {
-	return open_iface(key, value, extra_args);
+	int ret = open_iface(key, value, extra_args);
+	if (ret < 0)
+		return ret;
+	if (strcmp(key, ETH_PCAP_RX_IFACE_IN_ARG) == 0) {
+		struct pmd_devargs *pmd = extra_args;
+		unsigned int qid = pmd->num_of_queue - 1;
+
+		set_iface_direction(pmd->queue[qid].name,
+				pmd->queue[qid].pcap,
+				PCAP_D_IN);
+	}
+
+	return 0;
+}
+
+static inline int
+rx_iface_args_process(const char *key, const char *value, void *extra_args)
+{
+	if (strcmp(key, ETH_PCAP_RX_IFACE_ARG) == 0 ||
+			strcmp(key, ETH_PCAP_RX_IFACE_IN_ARG) == 0)
+		return open_rx_iface(key, value, extra_args);
+
+	return 0;
 }
 
 /*
@@ -964,12 +1003,13 @@ struct pmd_devargs {
 	is_rx_pcap = rte_kvargs_count(kvlist, ETH_PCAP_RX_PCAP_ARG) ? 1 : 0;
 	pcaps.num_of_queue = 0;
 
-	if (is_rx_pcap)
+	if (is_rx_pcap) {
 		ret = rte_kvargs_process(kvlist, ETH_PCAP_RX_PCAP_ARG,
 				&open_rx_pcap, &pcaps);
-	else
-		ret = rte_kvargs_process(kvlist, ETH_PCAP_RX_IFACE_ARG,
-				&open_rx_iface, &pcaps);
+	} else {
+		ret = rte_kvargs_process(kvlist, NULL,
+				&rx_iface_args_process, &pcaps);
+	}
 
 	if (ret < 0)
 		goto free_kvlist;
@@ -1035,6 +1075,7 @@ struct pmd_devargs {
 	ETH_PCAP_RX_PCAP_ARG "=<string> "
 	ETH_PCAP_TX_PCAP_ARG "=<string> "
 	ETH_PCAP_RX_IFACE_ARG "=<ifc> "
+	ETH_PCAP_RX_IFACE_IN_ARG "=<ifc> "
 	ETH_PCAP_TX_IFACE_ARG "=<ifc> "
 	ETH_PCAP_IFACE_ARG "=<ifc>");
 
-- 
1.9.1