// SPDX-License-Identifier: GPL-2.0
#include "bpf_tracing_net.h"
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_endian.h>
#include "test_tcpbpf.h"

struct tcpbpf_globals global = {};

/**
 * SOL_TCP is defined in <netinet/tcp.h> while
 * TCP_SAVED_SYN is defined in already included <linux/tcp.h>
 */
#ifndef SOL_TCP
#define SOL_TCP 6
#endif

static __always_inline int get_tp_window_clamp(struct bpf_sock_ops *skops)
{
        struct bpf_sock *sk;
        struct tcp_sock *tp;

        sk = skops->sk;
        if (!sk)
                return -1;
        tp = bpf_skc_to_tcp_sock(sk);
        if (!tp)
                return -1;
        return tp->window_clamp;
}

SEC("sockops")
int bpf_testcb(struct bpf_sock_ops *skops)
{
        char header[sizeof(struct ipv6hdr) + sizeof(struct tcphdr)];
        struct bpf_sock_ops *reuse = skops;
        struct tcphdr *thdr;
        int window_clamp = 9216;
        int save_syn = 1;
        int rv = -1;
        int v = 0;
        int op;

        /* Test reading fields in bpf_sock_ops using single register */
        asm volatile (
                "%[reuse] = *(u32 *)(%[reuse] +96)"
                : [reuse] "+r"(reuse)
                :);

        asm volatile (
                "%[op] = *(u32 *)(%[skops] +96)"
                : [op] "=r"(op)
                : [skops] "r"(skops)
                :);

        asm volatile (
                "r9 = %[skops];\n"
                "r8 = *(u32 *)(r9 +164);\n"
                "*(u32 *)(r9 +164) = r8;\n"
                :: [skops] "r"(skops)
                : "r9", "r8");

        asm volatile (
                "r1 = %[skops];\n"
                "r1 = *(u64 *)(r1 +184);\n"
                "if r1 == 0 goto +1;\n"
                "r1 = *(u32 *)(r1 +4);\n"
                :: [skops] "r"(skops):"r1");

        asm volatile (
                "r9 = %[skops];\n"
                "r9 = *(u64 *)(r9 +184);\n"
                "if r9 == 0 goto +1;\n"
                "r9 = *(u32 *)(r9 +4);\n"
                :: [skops] "r"(skops):"r9");

        asm volatile (
                "r1 = %[skops];\n"
                "r2 = *(u64 *)(r1 +184);\n"
                "if r2 == 0 goto +1;\n"
                "r2 = *(u32 *)(r2 +4);\n"
                :: [skops] "r"(skops):"r1", "r2");

        op = (int) skops->op;

        global.event_map |= (1 << op);

        switch (op) {
        case BPF_SOCK_OPS_TCP_CONNECT_CB:
                rv = bpf_setsockopt(skops, SOL_TCP, TCP_WINDOW_CLAMP,
                                    &window_clamp, sizeof(window_clamp));
                global.window_clamp_client = get_tp_window_clamp(skops);
                break;
        case BPF_SOCK_OPS_ACTIVE_ESTABLISHED_CB:
                /* Test failure to set largest cb flag (assumes not defined) */
                global.bad_cb_test_rv = bpf_sock_ops_cb_flags_set(skops, 0x80);
                /* Set callback */
                global.good_cb_test_rv = bpf_sock_ops_cb_flags_set(skops,
                                                 BPF_SOCK_OPS_STATE_CB_FLAG);
                break;
        case BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB:
                skops->sk_txhash = 0x12345f;
                v = 0xff;
                rv = bpf_setsockopt(skops, SOL_IPV6, IPV6_TCLASS, &v,
                                    sizeof(v));
                if (skops->family == AF_INET6) {
                        v = bpf_getsockopt(skops, IPPROTO_TCP, TCP_SAVED_SYN,
                                           header, (sizeof(struct ipv6hdr) +
                                                    sizeof(struct tcphdr)));
                        if (!v) {
                                int offset = sizeof(struct ipv6hdr);

                                thdr = (struct tcphdr *)(header + offset);
                                v = thdr->syn;

                                global.tcp_saved_syn = v;
                        }
                }
                rv = bpf_setsockopt(skops, SOL_TCP, TCP_WINDOW_CLAMP,
                                    &window_clamp, sizeof(window_clamp));

                global.window_clamp_server = get_tp_window_clamp(skops);
                break;
        case BPF_SOCK_OPS_RTO_CB:
                break;
        case BPF_SOCK_OPS_RETRANS_CB:
                break;
        case BPF_SOCK_OPS_STATE_CB:
                if (skops->args[1] == BPF_TCP_CLOSE) {
                        if (skops->args[0] == BPF_TCP_LISTEN) {
                                global.num_listen++;
                        } else {
                                global.total_retrans = skops->total_retrans;
                                global.data_segs_in = skops->data_segs_in;
                                global.data_segs_out = skops->data_segs_out;
                                global.bytes_received = skops->bytes_received;
                                global.bytes_acked = skops->bytes_acked;
                        }
                        global.num_close_events++;
                }
                break;
        case BPF_SOCK_OPS_TCP_LISTEN_CB:
                bpf_sock_ops_cb_flags_set(skops, BPF_SOCK_OPS_STATE_CB_FLAG);
                v = bpf_setsockopt(skops, IPPROTO_TCP, TCP_SAVE_SYN,
                                   &save_syn, sizeof(save_syn));
                /* Update global map w/ result of setsock opt */
                global.tcp_save_syn = v;
                break;
        default:
                rv = -1;
        }
        skops->reply = rv;
        return 1;
}
char _license[] SEC("license") = "GPL";