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0001 // SPDX-License-Identifier: GPL-2.0
0002 #include <linux/bpf.h>
0003 #include <bpf/bpf_helpers.h>
0004 
0005 char _license[] SEC("license") = "GPL";
0006 
0007 struct tcp_rtt_storage {
0008     __u32 invoked;
0009     __u32 dsack_dups;
0010     __u32 delivered;
0011     __u32 delivered_ce;
0012     __u32 icsk_retransmits;
0013 };
0014 
0015 struct {
0016     __uint(type, BPF_MAP_TYPE_SK_STORAGE);
0017     __uint(map_flags, BPF_F_NO_PREALLOC);
0018     __type(key, int);
0019     __type(value, struct tcp_rtt_storage);
0020 } socket_storage_map SEC(".maps");
0021 
0022 SEC("sockops")
0023 int _sockops(struct bpf_sock_ops *ctx)
0024 {
0025     struct tcp_rtt_storage *storage;
0026     struct bpf_tcp_sock *tcp_sk;
0027     int op = (int) ctx->op;
0028     struct bpf_sock *sk;
0029 
0030     sk = ctx->sk;
0031     if (!sk)
0032         return 1;
0033 
0034     storage = bpf_sk_storage_get(&socket_storage_map, sk, 0,
0035                      BPF_SK_STORAGE_GET_F_CREATE);
0036     if (!storage)
0037         return 1;
0038 
0039     if (op == BPF_SOCK_OPS_TCP_CONNECT_CB) {
0040         bpf_sock_ops_cb_flags_set(ctx, BPF_SOCK_OPS_RTT_CB_FLAG);
0041         return 1;
0042     }
0043 
0044     if (op != BPF_SOCK_OPS_RTT_CB)
0045         return 1;
0046 
0047     tcp_sk = bpf_tcp_sock(sk);
0048     if (!tcp_sk)
0049         return 1;
0050 
0051     storage->invoked++;
0052 
0053     storage->dsack_dups = tcp_sk->dsack_dups;
0054     storage->delivered = tcp_sk->delivered;
0055     storage->delivered_ce = tcp_sk->delivered_ce;
0056     storage->icsk_retransmits = tcp_sk->icsk_retransmits;
0057 
0058     return 1;
0059 }