Merge pull request #318 from alebsys/tcp-retransmit

Add tcp-retransmit example

Author: bobrik

examples/tcp-retransmit.bpf.c

@@ -0,0 +1,114 @@
+#include <vmlinux.h>
+#include <bpf/bpf_tracing.h>
+#include <bpf/bpf_core_read.h>
+#include "maps.bpf.h"
+
+#define MAX_ENTRIES 8192
+
+// Type of tcp retransmits
+#define RETRANSMIT 1
+#define TLP 2
+
+#define AF_INET 2
+#define AF_INET6 10
+
+#define UPPER_PORT_BOUND 32768
+
+struct ipv4_key_t {
+    u32 saddr;
+    u32 daddr;
+    u16 mainport;
+    u32 type;
+};
+
+struct ipv6_key_t {
+    u8 saddr[16];
+    u8 daddr[16];
+    u16 mainport;
+    u32 type;
+};
+
+struct {
+    __uint(type, BPF_MAP_TYPE_LRU_HASH);
+    __uint(max_entries, MAX_ENTRIES);
+    __type(key, struct ipv4_key_t);
+    __type(value, u64);
+} tcp_retransmit_ipv4_packets_total SEC(".maps");
+
+struct {
+    __uint(type, BPF_MAP_TYPE_LRU_HASH);
+    __uint(max_entries, MAX_ENTRIES);
+    __type(key, struct ipv6_key_t);
+    __type(value, u64);
+} tcp_retransmit_ipv6_packets_total SEC(".maps");
+
+static int trace_event(const struct sock *sk, u32 type)
+{
+    u32 family = sk->__sk_common.skc_family;
+
+    if (family == AF_INET) {
+        struct ipv4_key_t key;
+        __builtin_memset(&key, 0, sizeof(key));
+
+        key.saddr = sk->__sk_common.skc_rcv_saddr;
+        key.daddr = sk->__sk_common.skc_daddr;
+
+        u16 sport = sk->__sk_common.skc_num;
+        u16 dport = sk->__sk_common.skc_dport;
+        dport = __builtin_bswap16(dport);
+
+        if (sport <= dport) {
+            key.mainport = sport;
+        } else {
+            key.mainport = dport;
+        }
+
+        if (key.mainport >= UPPER_PORT_BOUND) {
+            key.mainport = 0;
+        }
+
+        key.type = type;
+
+        increment_map(&tcp_retransmit_ipv4_packets_total, &key, 1);
+
+    } else if (family == AF_INET6) {
+        struct ipv6_key_t key;
+        __builtin_memset(&key, 0, sizeof(key));
+
+        bpf_probe_read_kernel(&key.saddr, sizeof(key.saddr), sk->__sk_common.skc_v6_rcv_saddr.in6_u.u6_addr32);
+        bpf_probe_read_kernel(&key.daddr, sizeof(key.daddr), sk->__sk_common.skc_v6_daddr.in6_u.u6_addr32);
+
+        u16 sport = sk->__sk_common.skc_num;
+        u16 dport = sk->__sk_common.skc_dport;
+        dport = __builtin_bswap16(dport);
+
+        if (sport <= dport) {
+            key.mainport = sport;
+        } else {
+            key.mainport = dport;
+        }
+
+        if (key.mainport >= UPPER_PORT_BOUND) {
+            key.mainport = 0;
+        }
+
+        key.type = type;
+
+        increment_map(&tcp_retransmit_ipv6_packets_total, &key, 1);
+    }
+    return 0;
+}
+
+SEC("fentry/tcp_send_loss_probe")
+int BPF_PROG(tcp_send_loss_probe, struct sock *sk)
+{
+    return trace_event(sk, TLP);
+}
+
+SEC("fentry/tcp_retransmit_skb")
+int BPF_PROG(tcp_retransmit_skb, struct sock *sk)
+{
+    return trace_event(sk, RETRANSMIT);
+}
+
+char LICENSE[] SEC("license") = "GPL";

examples/tcp-retransmit.yaml

@@ -0,0 +1,48 @@
+metrics:
+    counters:
+      - name: tcp_retransmit_ipv4_packets_total
+        help: Total count of IPv4 TCP retransmissions
+        labels:
+          - name: local_ip
+            size: 4
+            decoders:
+              - name: inet_ip
+          - name: peer_ip
+            size: 4
+            decoders:
+              - name: inet_ip
+          - name: main_port
+            size: 4
+            decoders:
+              - name: uint
+          - name: type
+            size: 4
+            decoders:
+              - name: uint
+              - name: static_map
+                static_map:
+                  1: retransmit
+                  2: tail_loss_probe
+      - name: tcp_retransmit_ipv6_packets_total
+        help: Total count of IPv6 TCP retransmissions
+        labels:
+          - name: local_ip
+            size: 16
+            decoders:
+              - name: inet_ip
+          - name: peer_ip
+            size: 16
+            decoders:
+              - name: inet_ip
+          - name: main_port
+            size: 4
+            decoders:
+              - name: uint
+          - name: type
+            size: 4
+            decoders:
+              - name: uint
+              - name: static_map
+                static_map:
+                  1: retransmit
+                  2: tail_loss_probe