// SPDX-License-Identifier: GPL-2.0
#include <test_progs.h>
#include <net/if.h>
#include <linux/netfilter.h>
#include <network_helpers.h>
#include "ip_check_defrag.skel.h"
#include "ip_check_defrag_frags.h"

/*
 * This selftest spins up a client and an echo server, each in their own
 * network namespace. The client will send a fragmented message to the server.
 * The prog attached to the server will shoot down any fragments. Thus, if
 * the server is able to correctly echo back the message to the client, we will
 * have verified that netfilter is reassembling packets for us.
 *
 * Topology:
 * =========
 *           NS0         |         NS1
 *                       |
 *         client        |       server
 *       ----------      |     ----------
 *       |  veth0  | --------- |  veth1  |
 *       ----------    peer    ----------
 *                       |
 *                       |       with bpf
 */

#define NS0             "defrag_ns0"
#define NS1             "defrag_ns1"
#define VETH0           "veth0"
#define VETH1           "veth1"
#define VETH0_ADDR      "172.16.1.100"
#define VETH0_ADDR6     "fc00::100"
/* The following constants must stay in sync with `generate_udp_fragments.py` */
#define VETH1_ADDR      "172.16.1.200"
#define VETH1_ADDR6     "fc00::200"
#define CLIENT_PORT     48878
#define SERVER_PORT     48879
#define MAGIC_MESSAGE   "THIS IS THE ORIGINAL MESSAGE, PLEASE REASSEMBLE ME"

static int setup_topology(bool ipv6)
{
        bool up;
        int i;

        SYS(fail, "ip netns add " NS0);
        SYS(fail, "ip netns add " NS1);
        SYS(fail, "ip link add " VETH0 " netns " NS0 " type veth peer name " VETH1 " netns " NS1);
        if (ipv6) {
                SYS(fail, "ip -6 -net " NS0 " addr add " VETH0_ADDR6 "/64 dev " VETH0 " nodad");
                SYS(fail, "ip -6 -net " NS1 " addr add " VETH1_ADDR6 "/64 dev " VETH1 " nodad");
        } else {
                SYS(fail, "ip -net " NS0 " addr add " VETH0_ADDR "/24 dev " VETH0);
                SYS(fail, "ip -net " NS1 " addr add " VETH1_ADDR "/24 dev " VETH1);
        }
        SYS(fail, "ip -net " NS0 " link set dev " VETH0 " up");
        SYS(fail, "ip -net " NS1 " link set dev " VETH1 " up");

        /* Wait for up to 5s for links to come up */
        for (i = 0; i < 5; ++i) {
                if (ipv6)
                        up = !SYS_NOFAIL("ip netns exec " NS0 " ping -6 -c 1 -W 1 " VETH1_ADDR6);
                else
                        up = !SYS_NOFAIL("ip netns exec " NS0 " ping -c 1 -W 1 " VETH1_ADDR);

                if (up)
                        break;
        }

        return 0;
fail:
        return -1;
}

static void cleanup_topology(void)
{
        SYS_NOFAIL("test -f /var/run/netns/" NS0 " && ip netns delete " NS0);
        SYS_NOFAIL("test -f /var/run/netns/" NS1 " && ip netns delete " NS1);
}

static int attach(struct ip_check_defrag *skel, bool ipv6)
{
        LIBBPF_OPTS(bpf_netfilter_opts, opts,
                    .pf = ipv6 ? NFPROTO_IPV6 : NFPROTO_IPV4,
                    .priority = 42,
                    .flags = BPF_F_NETFILTER_IP_DEFRAG);
        struct nstoken *nstoken;
        int err = -1;

        nstoken = open_netns(NS1);
        if (!ASSERT_OK_PTR(nstoken, "setns"))
                goto out;

        skel->links.defrag = bpf_program__attach_netfilter(skel->progs.defrag, &opts);
        if (!ASSERT_OK_PTR(skel->links.defrag, "program attach"))
                goto out;

        err = 0;
out:
        close_netns(nstoken);
        return err;
}

static int send_frags(int client)
{
        struct sockaddr_storage saddr;
        struct sockaddr *saddr_p;
        socklen_t saddr_len;
        int err;

        saddr_p = (struct sockaddr *)&saddr;
        err = make_sockaddr(AF_INET, VETH1_ADDR, SERVER_PORT, &saddr, &saddr_len);
        if (!ASSERT_OK(err, "make_sockaddr"))
                return -1;

        err = sendto(client, frag_0, sizeof(frag_0), 0, saddr_p, saddr_len);
        if (!ASSERT_GE(err, 0, "sendto frag_0"))
                return -1;

        err = sendto(client, frag_1, sizeof(frag_1), 0, saddr_p, saddr_len);
        if (!ASSERT_GE(err, 0, "sendto frag_1"))
                return -1;

        err = sendto(client, frag_2, sizeof(frag_2), 0, saddr_p, saddr_len);
        if (!ASSERT_GE(err, 0, "sendto frag_2"))
                return -1;

        return 0;
}

static int send_frags6(int client)
{
        struct sockaddr_storage saddr;
        struct sockaddr *saddr_p;
        socklen_t saddr_len;
        int err;

        saddr_p = (struct sockaddr *)&saddr;
        /* Port needs to be set to 0 for raw ipv6 socket for some reason */
        err = make_sockaddr(AF_INET6, VETH1_ADDR6, 0, &saddr, &saddr_len);
        if (!ASSERT_OK(err, "make_sockaddr"))
                return -1;

        err = sendto(client, frag6_0, sizeof(frag6_0), 0, saddr_p, saddr_len);
        if (!ASSERT_GE(err, 0, "sendto frag6_0"))
                return -1;

        err = sendto(client, frag6_1, sizeof(frag6_1), 0, saddr_p, saddr_len);
        if (!ASSERT_GE(err, 0, "sendto frag6_1"))
                return -1;

        err = sendto(client, frag6_2, sizeof(frag6_2), 0, saddr_p, saddr_len);
        if (!ASSERT_GE(err, 0, "sendto frag6_2"))
                return -1;

        return 0;
}

void test_bpf_ip_check_defrag_ok(bool ipv6)
{
        int family = ipv6 ? AF_INET6 : AF_INET;
        struct network_helper_opts rx_opts = {
                .timeout_ms = 1000,
        };
        struct network_helper_opts tx_ops = {
                .timeout_ms = 1000,
                .proto = IPPROTO_RAW,
        };
        struct sockaddr_storage caddr;
        struct ip_check_defrag *skel;
        struct nstoken *nstoken;
        int client_tx_fd = -1;
        int client_rx_fd = -1;
        socklen_t caddr_len;
        int srv_fd = -1;
        char buf[1024];
        int len, err;

        skel = ip_check_defrag__open_and_load();
        if (!ASSERT_OK_PTR(skel, "skel_open"))
                return;

        if (!ASSERT_OK(setup_topology(ipv6), "setup_topology"))
                goto out;

        if (!ASSERT_OK(attach(skel, ipv6), "attach"))
                goto out;

        /* Start server in ns1 */
        nstoken = open_netns(NS1);
        if (!ASSERT_OK_PTR(nstoken, "setns ns1"))
                goto out;
        srv_fd = start_server(family, SOCK_DGRAM, NULL, SERVER_PORT, 0);
        close_netns(nstoken);
        if (!ASSERT_GE(srv_fd, 0, "start_server"))
                goto out;

        /* Open tx raw socket in ns0 */
        nstoken = open_netns(NS0);
        if (!ASSERT_OK_PTR(nstoken, "setns ns0"))
                goto out;
        client_tx_fd = client_socket(family, SOCK_RAW, &tx_ops);
        close_netns(nstoken);
        if (!ASSERT_GE(client_tx_fd, 0, "client_socket"))
                goto out;

        /* Open rx socket in ns0 */
        nstoken = open_netns(NS0);
        if (!ASSERT_OK_PTR(nstoken, "setns ns0"))
                goto out;
        client_rx_fd = client_socket(family, SOCK_DGRAM, &rx_opts);
        close_netns(nstoken);
        if (!ASSERT_GE(client_rx_fd, 0, "client_socket"))
                goto out;

        /* Bind rx socket to a premeditated port */
        memset(&caddr, 0, sizeof(caddr));
        nstoken = open_netns(NS0);
        if (!ASSERT_OK_PTR(nstoken, "setns ns0"))
                goto out;
        if (ipv6) {
                struct sockaddr_in6 *c = (struct sockaddr_in6 *)&caddr;

                c->sin6_family = AF_INET6;
                inet_pton(AF_INET6, VETH0_ADDR6, &c->sin6_addr);
                c->sin6_port = htons(CLIENT_PORT);
                err = bind(client_rx_fd, (struct sockaddr *)c, sizeof(*c));
        } else {
                struct sockaddr_in *c = (struct sockaddr_in *)&caddr;

                c->sin_family = AF_INET;
                inet_pton(AF_INET, VETH0_ADDR, &c->sin_addr);
                c->sin_port = htons(CLIENT_PORT);
                err = bind(client_rx_fd, (struct sockaddr *)c, sizeof(*c));
        }
        close_netns(nstoken);
        if (!ASSERT_OK(err, "bind"))
                goto out;

        /* Send message in fragments */
        if (ipv6) {
                if (!ASSERT_OK(send_frags6(client_tx_fd), "send_frags6"))
                        goto out;
        } else {
                if (!ASSERT_OK(send_frags(client_tx_fd), "send_frags"))
                        goto out;
        }

        if (!ASSERT_EQ(skel->bss->shootdowns, 0, "shootdowns"))
                goto out;

        /* Receive reassembled msg on server and echo back to client */
        caddr_len = sizeof(caddr);
        len = recvfrom(srv_fd, buf, sizeof(buf), 0, (struct sockaddr *)&caddr, &caddr_len);
        if (!ASSERT_GE(len, 0, "server recvfrom"))
                goto out;
        len = sendto(srv_fd, buf, len, 0, (struct sockaddr *)&caddr, caddr_len);
        if (!ASSERT_GE(len, 0, "server sendto"))
                goto out;

        /* Expect reassembed message to be echoed back */
        len = recvfrom(client_rx_fd, buf, sizeof(buf), 0, NULL, NULL);
        if (!ASSERT_EQ(len, sizeof(MAGIC_MESSAGE) - 1, "client short read"))
                goto out;

out:
        if (client_rx_fd != -1)
                close(client_rx_fd);
        if (client_tx_fd != -1)
                close(client_tx_fd);
        if (srv_fd != -1)
                close(srv_fd);
        cleanup_topology();
        ip_check_defrag__destroy(skel);
}

void test_bpf_ip_check_defrag(void)
{
        if (test__start_subtest("v4"))
                test_bpf_ip_check_defrag_ok(false);
        if (test__start_subtest("v6"))
                test_bpf_ip_check_defrag_ok(true);
}