// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
// Copyright (c) 2025 Cloudflare, Inc.

/* Tests for TCP port sharing (bind bucket reuse). */

#include <arpa/inet.h>
#include <net/if.h>
#include <sys/ioctl.h>
#include <fcntl.h>
#include <sched.h>
#include <stdlib.h>

#include "kselftest_harness.h"

#define DST_PORT 30000
#define SRC_PORT 40000

struct sockaddr_inet {
        union {
                struct sockaddr_storage ss;
                struct sockaddr_in6 v6;
                struct sockaddr_in v4;
                struct sockaddr sa;
        };
        socklen_t len;
        char str[INET6_ADDRSTRLEN + __builtin_strlen("[]:65535") + 1];
};

const int one = 1;

static int disconnect(int fd)
{
        return connect(fd, &(struct sockaddr){ AF_UNSPEC }, sizeof(struct sockaddr));
}

static int getsockname_port(int fd)
{
        struct sockaddr_inet addr = {};
        int err;

        addr.len = sizeof(addr);
        err = getsockname(fd, &addr.sa, &addr.len);
        if (err)
                return -1;

        switch (addr.sa.sa_family) {
        case AF_INET:
                return ntohs(addr.v4.sin_port);
        case AF_INET6:
                return ntohs(addr.v6.sin6_port);
        default:
                errno = EAFNOSUPPORT;
                return -1;
        }
}

static void make_inet_addr(int af, const char *ip, __u16 port,
                           struct sockaddr_inet *addr)
{
        const char *fmt = "";

        memset(addr, 0, sizeof(*addr));

        switch (af) {
        case AF_INET:
                addr->len = sizeof(addr->v4);
                addr->v4.sin_family = af;
                addr->v4.sin_port = htons(port);
                inet_pton(af, ip, &addr->v4.sin_addr);
                fmt = "%s:%hu";
                break;
        case AF_INET6:
                addr->len = sizeof(addr->v6);
                addr->v6.sin6_family = af;
                addr->v6.sin6_port = htons(port);
                inet_pton(af, ip, &addr->v6.sin6_addr);
                fmt = "[%s]:%hu";
                break;
        }

        snprintf(addr->str, sizeof(addr->str), fmt, ip, port);
}

FIXTURE(tcp_port_share) {};

FIXTURE_VARIANT(tcp_port_share) {
        int domain;
        /* IP to listen on and connect to */
        const char *dst_ip;
        /* Primary IP to connect from */
        const char *src1_ip;
        /* Secondary IP to connect from */
        const char *src2_ip;
        /* IP to bind to in order to block the source port */
        const char *bind_ip;
};

FIXTURE_VARIANT_ADD(tcp_port_share, ipv4) {
        .domain = AF_INET,
        .dst_ip = "127.0.0.1",
        .src1_ip = "127.1.1.1",
        .src2_ip = "127.2.2.2",
        .bind_ip = "127.3.3.3",
};

FIXTURE_VARIANT_ADD(tcp_port_share, ipv6) {
        .domain = AF_INET6,
        .dst_ip = "::1",
        .src1_ip = "2001:db8::1",
        .src2_ip = "2001:db8::2",
        .bind_ip = "2001:db8::3",
};

FIXTURE_SETUP(tcp_port_share)
{
        int sc;

        ASSERT_EQ(unshare(CLONE_NEWNET), 0);
        ASSERT_EQ(system("ip link set dev lo up"), 0);
        ASSERT_EQ(system("ip addr add dev lo 2001:db8::1/32 nodad"), 0);
        ASSERT_EQ(system("ip addr add dev lo 2001:db8::2/32 nodad"), 0);
        ASSERT_EQ(system("ip addr add dev lo 2001:db8::3/32 nodad"), 0);

        sc = open("/proc/sys/net/ipv4/ip_local_port_range", O_WRONLY);
        ASSERT_GE(sc, 0);
        ASSERT_GT(dprintf(sc, "%hu %hu\n", SRC_PORT, SRC_PORT), 0);
        ASSERT_EQ(close(sc), 0);
}

FIXTURE_TEARDOWN(tcp_port_share) {}

/* Verify that an ephemeral port becomes available again after the socket
 * bound to it and blocking it from reuse is closed.
 */
TEST_F(tcp_port_share, can_reuse_port_after_bind_and_close)
{
        const typeof(variant) v = variant;
        struct sockaddr_inet addr;
        int c1, c2, ln, pb;

        /* Listen on <dst_ip>:<DST_PORT> */
        ln = socket(v->domain, SOCK_STREAM, 0);
        ASSERT_GE(ln, 0) TH_LOG("socket(): %m");
        ASSERT_EQ(setsockopt(ln, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one)), 0);

        make_inet_addr(v->domain, v->dst_ip, DST_PORT, &addr);
        ASSERT_EQ(bind(ln, &addr.sa, addr.len), 0) TH_LOG("bind(%s): %m", addr.str);
        ASSERT_EQ(listen(ln, 2), 0);

        /* Connect from <src1_ip>:<SRC_PORT> */
        c1 = socket(v->domain, SOCK_STREAM, 0);
        ASSERT_GE(c1, 0) TH_LOG("socket(): %m");
        ASSERT_EQ(setsockopt(c1, SOL_IP, IP_BIND_ADDRESS_NO_PORT, &one, sizeof(one)), 0);

        make_inet_addr(v->domain, v->src1_ip, 0, &addr);
        ASSERT_EQ(bind(c1, &addr.sa, addr.len), 0) TH_LOG("bind(%s): %m", addr.str);

        make_inet_addr(v->domain, v->dst_ip, DST_PORT, &addr);
        ASSERT_EQ(connect(c1, &addr.sa, addr.len), 0) TH_LOG("connect(%s): %m", addr.str);
        ASSERT_EQ(getsockname_port(c1), SRC_PORT);

        /* Bind to <bind_ip>:<SRC_PORT>. Block the port from reuse. */
        pb = socket(v->domain, SOCK_STREAM, 0);
        ASSERT_GE(pb, 0) TH_LOG("socket(): %m");
        ASSERT_EQ(setsockopt(pb, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one)), 0);

        make_inet_addr(v->domain, v->bind_ip, SRC_PORT, &addr);
        ASSERT_EQ(bind(pb, &addr.sa, addr.len), 0) TH_LOG("bind(%s): %m", addr.str);

        /* Try to connect from <src2_ip>:<SRC_PORT>. Expect failure. */
        c2 = socket(v->domain, SOCK_STREAM, 0);
        ASSERT_GE(c2, 0) TH_LOG("socket");
        ASSERT_EQ(setsockopt(c2, SOL_IP, IP_BIND_ADDRESS_NO_PORT, &one, sizeof(one)), 0);

        make_inet_addr(v->domain, v->src2_ip, 0, &addr);
        ASSERT_EQ(bind(c2, &addr.sa, addr.len), 0) TH_LOG("bind(%s): %m", addr.str);

        make_inet_addr(v->domain, v->dst_ip, DST_PORT, &addr);
        ASSERT_EQ(connect(c2, &addr.sa, addr.len), -1) TH_LOG("connect(%s)", addr.str);
        ASSERT_EQ(errno, EADDRNOTAVAIL) TH_LOG("%m");

        /* Unbind from <bind_ip>:<SRC_PORT>. Unblock the port for reuse. */
        ASSERT_EQ(close(pb), 0);

        /* Connect again from <src2_ip>:<SRC_PORT> */
        EXPECT_EQ(connect(c2, &addr.sa, addr.len), 0) TH_LOG("connect(%s): %m", addr.str);
        EXPECT_EQ(getsockname_port(c2), SRC_PORT);

        ASSERT_EQ(close(c2), 0);
        ASSERT_EQ(close(c1), 0);
        ASSERT_EQ(close(ln), 0);
}

/* Verify that a socket auto-bound during connect() blocks port reuse after
 * disconnect (connect(AF_UNSPEC)) followed by an explicit port bind().
 */
TEST_F(tcp_port_share, port_block_after_disconnect)
{
        const typeof(variant) v = variant;
        struct sockaddr_inet addr;
        int c1, c2, ln, pb;

        /* Listen on <dst_ip>:<DST_PORT> */
        ln = socket(v->domain, SOCK_STREAM, 0);
        ASSERT_GE(ln, 0) TH_LOG("socket(): %m");
        ASSERT_EQ(setsockopt(ln, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one)), 0);

        make_inet_addr(v->domain, v->dst_ip, DST_PORT, &addr);
        ASSERT_EQ(bind(ln, &addr.sa, addr.len), 0) TH_LOG("bind(%s): %m", addr.str);
        ASSERT_EQ(listen(ln, 2), 0);

        /* Connect from <src1_ip>:<SRC_PORT> */
        c1 = socket(v->domain, SOCK_STREAM, 0);
        ASSERT_GE(c1, 0) TH_LOG("socket(): %m");
        ASSERT_EQ(setsockopt(c1, SOL_IP, IP_BIND_ADDRESS_NO_PORT, &one, sizeof(one)), 0);

        make_inet_addr(v->domain, v->src1_ip, 0, &addr);
        ASSERT_EQ(bind(c1, &addr.sa, addr.len), 0) TH_LOG("bind(%s): %m", addr.str);

        make_inet_addr(v->domain, v->dst_ip, DST_PORT, &addr);
        ASSERT_EQ(connect(c1, &addr.sa, addr.len), 0) TH_LOG("connect(%s): %m", addr.str);
        ASSERT_EQ(getsockname_port(c1), SRC_PORT);

        /* Disconnect the socket and bind it to <bind_ip>:<SRC_PORT> to block the port */
        ASSERT_EQ(disconnect(c1), 0) TH_LOG("disconnect: %m");
        ASSERT_EQ(setsockopt(c1, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one)), 0);

        make_inet_addr(v->domain, v->bind_ip, SRC_PORT, &addr);
        ASSERT_EQ(bind(c1, &addr.sa, addr.len), 0) TH_LOG("bind(%s): %m", addr.str);

        /* Trigger port-addr bucket state update with another bind() and close() */
        pb = socket(v->domain, SOCK_STREAM, 0);
        ASSERT_GE(pb, 0) TH_LOG("socket(): %m");
        ASSERT_EQ(setsockopt(pb, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one)), 0);

        make_inet_addr(v->domain, v->bind_ip, SRC_PORT, &addr);
        ASSERT_EQ(bind(pb, &addr.sa, addr.len), 0) TH_LOG("bind(%s): %m", addr.str);

        ASSERT_EQ(close(pb), 0);

        /* Connect from <src2_ip>:<SRC_PORT>. Expect failure. */
        c2 = socket(v->domain, SOCK_STREAM, 0);
        ASSERT_GE(c2, 0) TH_LOG("socket: %m");
        ASSERT_EQ(setsockopt(c2, SOL_IP, IP_BIND_ADDRESS_NO_PORT, &one, sizeof(one)), 0);

        make_inet_addr(v->domain, v->src2_ip, 0, &addr);
        ASSERT_EQ(bind(c2, &addr.sa, addr.len), 0) TH_LOG("bind(%s): %m", addr.str);

        make_inet_addr(v->domain, v->dst_ip, DST_PORT, &addr);
        EXPECT_EQ(connect(c2, &addr.sa, addr.len), -1) TH_LOG("connect(%s)", addr.str);
        EXPECT_EQ(errno, EADDRNOTAVAIL) TH_LOG("%m");

        ASSERT_EQ(close(c2), 0);
        ASSERT_EQ(close(c1), 0);
        ASSERT_EQ(close(ln), 0);
}

TEST_HARNESS_MAIN