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// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2021 Facebook */
#include "bpf_iter.h"
#include "bpf_tracing_net.h"
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_endian.h>
#define bpf_tcp_sk(skc) ({ \
struct sock_common *_skc = skc; \
sk = NULL; \
tp = NULL; \
if (_skc) { \
tp = bpf_skc_to_tcp_sock(_skc); \
sk = (struct sock *)tp; \
} \
tp; \
})
unsigned short reuse_listen_hport = 0;
unsigned short listen_hport = 0;
char cubic_cc[TCP_CA_NAME_MAX] = "bpf_cubic";
char dctcp_cc[TCP_CA_NAME_MAX] = "bpf_dctcp";
bool random_retry = false;
static bool tcp_cc_eq(const char *a, const char *b)
{
int i;
for (i = 0; i < TCP_CA_NAME_MAX; i++) {
if (a[i] != b[i])
return false;
if (!a[i])
break;
}
return true;
}
SEC("iter/tcp")
int change_tcp_cc(struct bpf_iter__tcp *ctx)
{
char cur_cc[TCP_CA_NAME_MAX];
struct tcp_sock *tp;
struct sock *sk;
if (!bpf_tcp_sk(ctx->sk_common))
return 0;
if (sk->sk_family != AF_INET6 ||
(sk->sk_state != TCP_LISTEN &&
sk->sk_state != TCP_ESTABLISHED) ||
(sk->sk_num != reuse_listen_hport &&
sk->sk_num != listen_hport &&
bpf_ntohs(sk->sk_dport) != listen_hport))
return 0;
if (bpf_getsockopt(tp, SOL_TCP, TCP_CONGESTION,
cur_cc, sizeof(cur_cc)))
return 0;
if (!tcp_cc_eq(cur_cc, cubic_cc))
return 0;
if (random_retry && bpf_get_prandom_u32() % 4 == 1)
return 1;
bpf_setsockopt(tp, SOL_TCP, TCP_CONGESTION, dctcp_cc, sizeof(dctcp_cc));
return 0;
}
char _license[] SEC("license") = "GPL";
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