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-rw-r--r--usage/bpf.c102
1 files changed, 102 insertions, 0 deletions
diff --git a/usage/bpf.c b/usage/bpf.c
new file mode 100644
index 0000000..8b2343a
--- /dev/null
+++ b/usage/bpf.c
@@ -0,0 +1,102 @@
+#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, __u64); // source mac 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, __u64); // destination mac 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 __u64 nchar6_to_u64(unsigned char bytes[6])
+{
+ union {
+ char bytes[6];
+ __u64 i;
+ } ret;
+
+ ret.i = 0;
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+ ret.bytes[0] = bytes[5];
+ ret.bytes[1] = bytes[4];
+ ret.bytes[2] = bytes[3];
+ ret.bytes[3] = bytes[2];
+ ret.bytes[4] = bytes[1];
+ ret.bytes[5] = bytes[0];
+#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
+ ret.bytes[0] = bytes[0];
+ ret.bytes[1] = bytes[1];
+ ret.bytes[2] = bytes[2];
+ ret.bytes[3] = bytes[3];
+ ret.bytes[4] = bytes[4];
+ ret.bytes[5] = bytes[5];
+#endif
+
+ return ret.i;
+}
+
+static __always_inline int update_usage(void *map, struct __sk_buff *skb,
+ update_usage_t traffic)
+{
+ __u64 mac, len, *usage;
+
+ void *data_end = (void *)(long)skb->data_end;
+ struct ethhdr *eth = (void *)(long)skb->data;
+
+ if ((void *) (eth + 1) > data_end)
+ return TCX_PASS;
+
+ if (skb->protocol != bpf_htons(ETH_P_IP) &&
+ skb->protocol != bpf_htons(ETH_P_IPV6)) {
+ return TCX_PASS;
+ }
+
+ len = skb->len - sizeof(struct ethhdr);
+ if (traffic == UPDATE_USAGE_INGRESS) {
+ mac = nchar6_to_u64(eth->h_source);
+ } else {
+ mac = nchar6_to_u64(eth->h_dest);
+ }
+
+ usage = bpf_map_lookup_elem(map, &mac);
+ if (!usage) {
+ /* no entry in the map for this IP address yet. */
+ bpf_map_update_elem(map, &mac, &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);
+}