1 files changed, 73 insertions, 0 deletions
diff --git a/bpf/bpf_usage.c b/bpf/bpf_usage.c
new file mode 100644
index 0000000..5e505da
--- /dev/null
+++ b/bpf/bpf_usage.c
@@ -0,0 +1,73 @@
+#include <linux/bpf.h>
+#include <linux/if_ether.h>
+#include <linux/ip.h>
+
+#include <bpf/bpf_endian.h>
+#include <bpf/bpf_helpers.h>
+
+#define MAX_MAP_ENTRIES 4096
+
+char __license[] SEC("license") = "GPL";
+
+struct {
+	__uint(type, BPF_MAP_TYPE_LRU_HASH);
+	__uint(max_entries, MAX_MAP_ENTRIES);
+	__type(key, __u32);   // source IPv4 address
+	__type(value, __u64); // no of bytes
+} ingress_ip4_usage_map SEC(".maps");
+
+struct {
+	__uint(type, BPF_MAP_TYPE_LRU_HASH);
+	__uint(max_entries, MAX_MAP_ENTRIES);
+	__type(key, __u32);   // destination IPv4 address
+	__type(value, __u64); // no of bytes
+} egress_ip4_usage_map SEC(".maps");
+
+typedef enum {
+	UPDATE_USAGE_INGRESS,
+	UPDATE_USAGE_EGRESS,
+} update_usage_t;
+
+static __always_inline int update_usage(void *map, struct __sk_buff *skb,
+					update_usage_t traffic)
+{
+	__u32 ip4;
+	__u64 len, *usage;
+
+	void *data_end = (void *)(long)skb->data_end;
+	void *data = (void *)(long)skb->data;
+	struct iphdr *ip = data + sizeof(struct ethhdr);
+
+	if (skb->protocol != bpf_htons(ETH_P_IP))
+		return TCX_PASS;
+	else if ((void *)(ip + 1) > data_end)
+		return TCX_PASS;
+
+	if (traffic == UPDATE_USAGE_INGRESS)
+		ip4 = ip->saddr;
+	else
+		ip4 = ip->daddr;
+	len = skb->len - sizeof(struct ethhdr);
+
+	usage = bpf_map_lookup_elem(map, &ip4);
+	if (!usage) {
+		/* no entry in the map for this IP address yet. */
+		bpf_map_update_elem(map, &ip4, &len, BPF_ANY);
+	} else {
+		__sync_fetch_and_add(usage, len);
+	}
+
+	return TCX_PASS;
+}
+
+SEC("tc")
+int ingress_func(struct __sk_buff *skb)
+{
+	return update_usage(&ingress_ip4_usage_map, skb, UPDATE_USAGE_INGRESS);
+}
+
+SEC("tc")
+int egress__func(struct __sk_buff *skb)
+{
+	return update_usage(&egress_ip4_usage_map, skb, UPDATE_USAGE_EGRESS);
+}