1 files changed, 89 insertions, 0 deletions
diff --git a/libs/libpfring/patches/002-implement-probabilistic-sampling.patch b/libs/libpfring/patches/002-implement-probabilistic-sampling.patch
new file mode 100644
index 000000000..d7b3e8339
--- /dev/null
+++ b/libs/libpfring/patches/002-implement-probabilistic-sampling.patch
@@ -0,0 +1,89 @@
+From 405caa1424358032574230ec5479e64834869298 Mon Sep 17 00:00:00 2001
+From: Alfredo Cardigliano <cardigliano@ntop.org>
+Date: Thu, 13 Apr 2023 13:03:28 +0200
+Subject: [PATCH] Implement probabilistic sampling
+
+---
+ kernel/linux/pf_ring.h |  4 +++-
+ kernel/pf_ring.c       | 34 ++++++++++++++++++++++++----------
+ 2 files changed, 27 insertions(+), 11 deletions(-)
+
+--- a/kernel/linux/pf_ring.h
++++ b/kernel/linux/pf_ring.h
+@@ -1310,7 +1310,9 @@ struct pf_ring_socket {
+   u_char *ring_slots;       /* Points to ring_memory+sizeof(FlowSlotInfo) */
+ 
+   /* Packet Sampling */
+-  u_int32_t pktToSample, sample_rate;
++  u_int32_t sample_rate;
++  u_int32_t pkts_to_sample;
++  u_int32_t sample_rnd_shift;
+ 
+   /* Virtual Filtering Device */
+   virtual_filtering_device_element *v_filtering_dev;
+--- a/kernel/pf_ring.c
++++ b/kernel/pf_ring.c
+@@ -3695,6 +3695,26 @@ int bpf_filter_skb(struct sk_buff *skb,
+ 
+ /* ********************************** */
+ 
++int sample_packet(struct pf_ring_socket *pfr) {
++  if(pfr->pkts_to_sample <= 1) {
++    u_int32_t rnd = 0;
++
++    get_random_bytes(&rnd, sizeof(u_int32_t));
++    rnd = rnd % pfr->sample_rate;
++
++    pfr->pkts_to_sample = pfr->sample_rate - pfr->sample_rnd_shift + rnd;
++
++    pfr->sample_rnd_shift = rnd;
++
++    return 1; /* Pass packet */
++  } else {
++    pfr->pkts_to_sample--;
++    return 0; /* Discard packet */
++  }
++}
++
++/* ********************************** */
++
+ u_int32_t default_rehash_rss_func(struct sk_buff *skb, struct pfring_pkthdr *hdr)
+ {
+   return hash_pkt_header(hdr, 0);
+@@ -3805,12 +3825,9 @@ static int add_skb_to_ring(struct sk_buf
+     if(pfr->sample_rate > 1) {
+       spin_lock_bh(&pfr->ring_index_lock);
+ 
+-      if(pfr->pktToSample <= 1) {
+-	pfr->pktToSample = pfr->sample_rate;
+-      } else {
++      if(!sample_packet(pfr)) {
++        /* Discard packet */
+         pfr->slots_info->tot_pkts++;
+-	pfr->pktToSample--;
+-
+ 	spin_unlock_bh(&pfr->ring_index_lock);
+ 	atomic_dec(&pfr->num_ring_users);
+ 	return(-1);
+@@ -4161,11 +4178,8 @@ int pf_ring_skb_ring_handler(struct sk_b
+ 
+         if(pfr->sample_rate > 1) {
+           spin_lock_bh(&pfr->ring_index_lock);
+-          if(pfr->pktToSample <= 1) {
+-            pfr->pktToSample = pfr->sample_rate;
+-          } else {
++          if (!sample_packet(pfr)) {
+             pfr->slots_info->tot_pkts++;
+-            pfr->pktToSample--;
+             rc = 0;
+           }
+           spin_unlock_bh(&pfr->ring_index_lock);
+@@ -7957,7 +7971,7 @@ static int ring_getsockopt(struct socket
+ 	if(copy_to_user(optval, lowest_if_mac, ETH_ALEN))
+ 	  return(-EFAULT);
+       } else {
+-        char *dev_addr = pfr->ring_dev->dev->dev_addr;
++        const char *dev_addr = pfr->ring_dev->dev->dev_addr;
+ 
+         if (dev_addr == NULL) /* e.g. 'any' device */
+           dev_addr = empty_mac;