test_packet_id.c

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/*
 *  OpenVPN -- An application to securely tunnel IP networks
 *             over a single UDP port, with support for SSL/TLS-based
 *             session authentication and key exchange,
 *             packet encryption, packet authentication, and
 *             packet compression.
 *
 *  Copyright (C) 2016-2026 Sentyron B.V. <openvpn@sentyron.com>
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License version 2
 *  as published by the Free Software Foundation.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program (see the file COPYING included with this
 *  distribution); if not, see <https://www.gnu.org/licenses/>.
 */
 
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
 
#include "syshead.h"
 
#include <stdarg.h>
#include <stddef.h>
#include <setjmp.h>
#include <cmocka.h>
 
#include "packet_id.h"
#include "reliable.h"
#include "test_common.h"
 
struct test_packet_id_write_data
{
    struct
    {
        uint32_t buf_id;
        uint32_t buf_time;
    } test_buf_data;
    struct buffer test_buf;
    struct packet_id_send pis;
    struct gc_arena gc;
};
 
static int
test_packet_id_write_setup(void **state)
{
    struct test_packet_id_write_data *data = calloc(1, sizeof(struct test_packet_id_write_data));
 
    if (!data)
    {
        return -1;
    }
 
    data->test_buf.data = (void *)&data->test_buf_data;
    data->test_buf.capacity = sizeof(data->test_buf_data);
    data->gc = gc_new();
 
    *state = data;
    return 0;
}
 
static int
test_packet_id_write_teardown(void **state)
{
    struct test_packet_id_write_data *data = *state;
    gc_free(&data->gc);
    free(*state);
    return 0;
}
 
static void
test_packet_id_write_short(void **state)
{
    struct test_packet_id_write_data *data = *state;
 
    now = 5010;
    assert_true(packet_id_write(&data->pis, &data->test_buf, false, false));
    assert_int_equal(data->pis.id, 1);
    assert_int_equal(data->test_buf_data.buf_id, htonl(1));
    assert_int_equal(data->test_buf_data.buf_time, 0);
}
 
static void
test_packet_id_write_long(void **state)
{
    struct test_packet_id_write_data *data = *state;
 
    now = 5010;
    assert_true(packet_id_write(&data->pis, &data->test_buf, true, false));
    assert_int_equal(data->pis.id, 1);
    assert_int_equal(data->pis.time, now);
    assert_int_equal(data->test_buf_data.buf_id, htonl(1));
    assert_int_equal(data->test_buf_data.buf_time, htonl((uint32_t)now));
}
 
static void
test_packet_id_write_short_prepend(void **state)
{
    struct test_packet_id_write_data *data = *state;
 
    data->test_buf.offset = sizeof(packet_id_type);
    now = 5010;
    assert_true(packet_id_write(&data->pis, &data->test_buf, false, true));
    assert_int_equal(data->pis.id, 1);
    assert_int_equal(data->test_buf_data.buf_id, htonl(1));
    assert_int_equal(data->test_buf_data.buf_time, 0);
}
 
static void
test_packet_id_write_long_prepend(void **state)
{
    struct test_packet_id_write_data *data = *state;
 
    data->test_buf.offset = sizeof(data->test_buf_data);
    now = 5010;
    assert_true(packet_id_write(&data->pis, &data->test_buf, true, true));
    assert_int_equal(data->pis.id, 1);
    assert_int_equal(data->pis.time, now);
    assert_int_equal(data->test_buf_data.buf_id, htonl(1));
    assert_int_equal(data->test_buf_data.buf_time, htonl((uint32_t)now));
}
 
static void
test_packet_id_write_short_wrap(void **state)
{
    struct test_packet_id_write_data *data = *state;
 
    /* maximum 32-bit packet id */
    data->pis.id = (packet_id_type)(~0);
    assert_false(packet_id_write(&data->pis, &data->test_buf, false, false));
}
 
static void
test_packet_id_write_long_wrap(void **state)
{
    struct test_packet_id_write_data *data = *state;
 
    /* maximum 32-bit packet id */
    data->pis.id = (packet_id_type)(~0);
    data->pis.time = 5006;
 
    /* Write fails if time did not change */
    now = 5006;
    assert_false(packet_id_write(&data->pis, &data->test_buf, true, false));
 
    /* Write succeeds if time moved forward */
    now = 5010;
    assert_true(packet_id_write(&data->pis, &data->test_buf, true, false));
 
    assert_int_equal(data->pis.id, 1);
    assert_int_equal(data->pis.time, now);
    assert_int_equal(data->test_buf_data.buf_id, htonl(1));
    assert_int_equal(data->test_buf_data.buf_time, htonl((uint32_t)now));
}
 
static void
test_get_num_output_sequenced_available(void **state)
{
    struct reliable *rel = malloc(sizeof(struct reliable));
    assert_non_null(rel);
    reliable_init(rel, 100, 50, 8, false);
 
    rel->array[5].active = true;
    rel->array[5].packet_id = 100;
 
    rel->packet_id = 103;
 
    assert_int_equal(5, reliable_get_num_output_sequenced_available(rel));
 
    rel->array[6].active = true;
    rel->array[6].packet_id = 97;
    assert_int_equal(2, reliable_get_num_output_sequenced_available(rel));
 
    /* test ids close to int/unsigned int barrier */
 
    rel->array[5].active = true;
    rel->array[5].packet_id = (0x80000000u - 3);
    rel->array[6].active = false;
    rel->packet_id = (0x80000000u - 1);
 
    assert_int_equal(6, reliable_get_num_output_sequenced_available(rel));
 
    rel->array[5].active = true;
    rel->array[5].packet_id = (0x80000000u - 3);
    rel->packet_id = 0x80000001u;
 
    assert_int_equal(4, reliable_get_num_output_sequenced_available(rel));
 
 
    /* test wrapping */
    rel->array[5].active = true;
    rel->array[5].packet_id = (0xffffffffu - 3);
    rel->array[6].active = false;
    rel->packet_id = (0xffffffffu - 1);
 
    assert_int_equal(6, reliable_get_num_output_sequenced_available(rel));
 
    rel->array[2].packet_id = 0;
    rel->array[2].active = true;
 
    assert_int_equal(6, reliable_get_num_output_sequenced_available(rel));
 
    rel->packet_id = 3;
    assert_int_equal(1, reliable_get_num_output_sequenced_available(rel));
 
    reliable_free(rel);
}
 
static void
test_packet_id_write_epoch(void **state)
{
    struct test_packet_id_write_data *data = *state;
 
    struct buffer buf = alloc_buf_gc(128, &data->gc);
 
    /* test normal writing of packet id to the buffer */
    assert_true(packet_id_write_epoch(&data->pis, 0x23, &buf));
 
    assert_int_equal(buf.len, 8);
    uint8_t expected_header[8] = { 0x00, 0x23, 0, 0, 0, 0, 0, 1 };
    assert_memory_equal(BPTR(&buf), expected_header, 8);
 
    /* too small buffer should error out */
    struct buffer buf_short = alloc_buf_gc(5, &data->gc);
    assert_false(packet_id_write_epoch(&data->pis, 0xabde, &buf_short));
 
    /* test a true 48 bit packet id */
    data->pis.id = 0xfa079ab9d2e8;
    struct buffer buf_48 = alloc_buf_gc(128, &data->gc);
    assert_true(packet_id_write_epoch(&data->pis, 0xfffe, &buf_48));
    uint8_t expected_header_48[8] = { 0xff, 0xfe, 0xfa, 0x07, 0x9a, 0xb9, 0xd2, 0xe9 };
    assert_memory_equal(BPTR(&buf_48), expected_header_48, 8);
 
    /* test writing/checking the 48 bit per epoch packet counter
     * overflow */
    data->pis.id = 0xfffffffffffe;
    struct buffer buf_of = alloc_buf_gc(128, &data->gc);
    assert_true(packet_id_write_epoch(&data->pis, 0xf00f, &buf_of));
    uint8_t expected_header_of[8] = { 0xf0, 0x0f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
    assert_memory_equal(BPTR(&buf_of), expected_header_of, 8);
 
    /* This is go over 2^48 - 1 and should error out. */
    assert_false(packet_id_write_epoch(&data->pis, 0xf00f, &buf_of));
 
    /* Now read back the packet ids and check if they are the same as what we
     * have written */
    struct packet_id_net pin;
    assert_int_equal(packet_id_read_epoch(&pin, &buf), 0x23);
    assert_int_equal(pin.id, 1);
 
    assert_int_equal(packet_id_read_epoch(&pin, &buf_48), 0xfffe);
    assert_int_equal(pin.id, 0xfa079ab9d2e9);
 
    assert_int_equal(packet_id_read_epoch(&pin, &buf_of), 0xf00f);
    assert_int_equal(pin.id, 0xffffffffffff);
}
 
static void
test_copy_acks_to_lru(void **state)
{
    struct reliable_ack ack = { .len = 4, .packet_id = { 2, 1, 3, 2 } };
 
    struct reliable_ack mru_ack = { 0 };
 
    /* Test copying to empty ack structure */
    copy_acks_to_mru(&ack, &mru_ack, 4);
    assert_int_equal(mru_ack.len, 3);
    assert_int_equal(mru_ack.packet_id[0], 2);
    assert_int_equal(mru_ack.packet_id[1], 1);
    assert_int_equal(mru_ack.packet_id[2], 3);
 
    /* Copying again should not change the result */
    copy_acks_to_mru(&ack, &mru_ack, 4);
    assert_int_equal(mru_ack.len, 3);
    assert_int_equal(mru_ack.packet_id[0], 2);
    assert_int_equal(mru_ack.packet_id[1], 1);
    assert_int_equal(mru_ack.packet_id[2], 3);
 
    /* Copying just the first two element should not change the order
     * as they are still the most recent*/
    struct reliable_ack mru_ack2 = mru_ack;
    copy_acks_to_mru(&ack, &mru_ack2, 2);
    assert_int_equal(mru_ack2.packet_id[0], 2);
    assert_int_equal(mru_ack2.packet_id[1], 1);
    assert_int_equal(mru_ack2.packet_id[2], 3);
 
    /* Adding just two packets shoudl ignore the 42 in array and
     * reorder the order in the MRU */
    struct reliable_ack ack2 = { .len = 3, .packet_id = { 3, 2, 42 } };
    copy_acks_to_mru(&ack2, &mru_ack2, 2);
    assert_int_equal(mru_ack2.packet_id[0], 3);
    assert_int_equal(mru_ack2.packet_id[1], 2);
    assert_int_equal(mru_ack2.packet_id[2], 1);
 
    /* Copying a zero array into it should also change nothing */
    struct reliable_ack empty_ack = { .len = 0 };
    copy_acks_to_mru(&empty_ack, &mru_ack, 0);
    assert_int_equal(mru_ack.len, 3);
    assert_int_equal(mru_ack.packet_id[0], 2);
    assert_int_equal(mru_ack.packet_id[1], 1);
    assert_int_equal(mru_ack.packet_id[2], 3);
 
    /* Or should just 0 elements of the ack */
    copy_acks_to_mru(&ack, &mru_ack, 0);
    assert_int_equal(mru_ack.len, 3);
    assert_int_equal(mru_ack.packet_id[0], 2);
    assert_int_equal(mru_ack.packet_id[1], 1);
    assert_int_equal(mru_ack.packet_id[2], 3);
 
    struct reliable_ack ack3 = { .len = 7, .packet_id = { 5, 6, 7, 8, 9, 10, 11 } };
 
    /* Adding multiple acks tests if the a full array is handled correctly */
    copy_acks_to_mru(&ack3, &mru_ack, 7);
 
    struct reliable_ack expected_ack = { .len = 8, .packet_id = { 5, 6, 7, 8, 9, 10, 11, 2 } };
    assert_int_equal(mru_ack.len, expected_ack.len);
 
    assert_memory_equal(mru_ack.packet_id, expected_ack.packet_id, sizeof(expected_ack.packet_id));
}
 
static void
test_packet_id_window(void **state)
{
    struct reliable rel = { 0 };
    rel.packet_id = 1;
 
    assert_true(validate_packet_id_window(&rel, 0));
 
    /* packet id 1 is outside the window as it is the *next* packet id */
    assert_false(validate_packet_id_window(&rel, 1));
 
    /* wrapped around packet id, "-2" */
    assert_true(validate_packet_id_window(&rel, 0xFFFFFFFD));
 
    /* wrapped around packet id, "-10" */
    assert_true(validate_packet_id_window(&rel, 0xFFFFFFF6));
 
    /* wrapped around packet id, "-11" */
    assert_false(validate_packet_id_window(&rel, 0xFFFFFFF5));
    assert_false(validate_packet_id_window(&rel, 0x80000000));
 
    rel.packet_id = 0x80000000;
 
    /* near the signed/usigned integer area */
    assert_false(validate_packet_id_window(&rel, 0x80000001));
    assert_true(validate_packet_id_window(&rel, 0x7fffffff));
    assert_true(validate_packet_id_window(&rel, 0x7ffffff5));
    assert_false(validate_packet_id_window(&rel, 0x7ffffff4));
 
    rel.packet_id = 0xFFFFFFFD;
    assert_false(validate_packet_id_window(&rel, 0xFFFFFFFD));
    assert_false(validate_packet_id_window(&rel, 0));
    assert_false(validate_packet_id_window(&rel, 1));
    assert_false(validate_packet_id_window(&rel, 0xFFFFFFFE));
    assert_false(validate_packet_id_window(&rel, 0xFFFFFFFF));
    assert_true(validate_packet_id_window(&rel, 0xFFFFFFF3));
    assert_true(validate_packet_id_window(&rel, 0xFFFFFFF2));
    assert_false(validate_packet_id_window(&rel, 0xFFFFFFF1));
 
    rel.packet_id = 500;
    assert_false(validate_packet_id_window(&rel, 501));
    assert_true(validate_packet_id_window(&rel, 497));
    assert_true(validate_packet_id_window(&rel, 500 - (RELIABLE_CAPACITY - 1)));
    assert_false(validate_packet_id_window(&rel, 500 - RELIABLE_CAPACITY));
}
 
 
/* The fix keeps the timeout well below this; the broken code grows past it.
 * A plain number, so the test builds with or without the fix. */
#define SANE_TIMEOUT_BOUND (10 * 1000 * 1000)
 
static struct reliable *
test_reliable_new(void)
{
    struct reliable *rel = malloc(sizeof(struct reliable));
    assert_non_null(rel);
    /* reliable_init() zeroes everything, so each test only sets the
     * fields it actually needs. */
    reliable_init(rel, 100, 50, 8, false);
    rel->initial_timeout = 2;
    return rel;
}
 
/*
 * Each retransmit doubles the timeout. If a peer keeps forcing retransmits,
 * the broken code doubles it forever: after about 30 rounds it overflows and
 * turns zero or negative, and then the packet is resent nonstop (the flood).
 * The fix caps the doubling. This test forces many retransmits and checks the
 * timeout never overflows or grows without limit.
 */
static void
test_reliable_backoff_is_bounded(void **state)
{
    (void)state;
    now = 1000;
 
    struct reliable *rel = test_reliable_new();
 
    struct reliable_entry *e = &rel->array[0];
    e->active = true;
    e->packet_id = 1;
    e->timeout = rel->initial_timeout;
    rel->packet_id = 2;
 
    for (int i = 0; i < 40; ++i)
    {
        /* make the packet due for a fast retransmit */
        e->n_acks = N_ACK_RETRANSMIT;
 
        int opcode;
        struct buffer *buf = reliable_send(rel, &opcode);
        /* our one active packet is the one picked to send */
        assert_ptr_equal(buf, &e->buf);
 
        /* a zero or negative timeout would resend with no delay (the flood) */
        assert_true(e->timeout > 0);
        /* the timeout must stop growing, not double forever */
        assert_true(e->timeout <= SANE_TIMEOUT_BOUND);
    }
 
    reliable_free(rel);
}
 
/*
 * An ACK should only count if it is for a packet we actually sent. If the
 * broken code accepts ACKs for packets that were never sent, a peer can force
 * early retransmits at will (which then feeds the timeout overflow above).
 * These two cases send such bogus ACKs and check they are ignored.
 */
static void
test_reliable_purge_ignores_forged_acks(void **state)
{
    (void)state;
 
    /* Case (a): an ACK for pid 0x40000000, which we never sent (we only sent
     * 0 and 1). The old "e->packet_id < pid" check treats it as newer and
     * counts it. It should be ignored. */
    {
        struct reliable *rel = test_reliable_new();
        struct reliable_entry *e = &rel->array[0];
        e->active = true;
        e->packet_id = 1;
        rel->packet_id = 2; /* only pids 0 and 1 were ever sent */
 
        struct reliable_ack ack = { .len = 1, .packet_id = { 0x40000000 } };
        reliable_send_purge(rel, &ack);
 
        /* the bogus ACK must not be counted */
        assert_int_equal(e->n_acks, 0);
        /* and must not drop our real packet */
        assert_true(e->active);
        reliable_free(rel);
    }
 
    /* Case (b): an ACK for pid 0xFFFFFFFF. It is inside the send window, so
     * it passes the window check, but ids wrap around and 0xFFFFFFFF is really
     * older than our pid 1. A plain "<" thinks it is newer and counts it; the
     * wraparound-aware comparison must not. */
    {
        struct reliable *rel = test_reliable_new();
        struct reliable_entry *e = &rel->array[0];
        e->active = true;
        e->packet_id = 1;
        rel->packet_id = 2;
 
        struct reliable_ack ack = { .len = 1, .packet_id = { 0xFFFFFFFF } };
        reliable_send_purge(rel, &ack);
 
        /* the bogus ACK must not be counted */
        assert_int_equal(e->n_acks, 0);
        /* and must not drop our real packet */
        assert_true(e->active);
        reliable_free(rel);
    }
}
 
/*
 * Sanity check: a real ACK must still work. Acknowledging a higher packet
 * should drop that packet and count once towards resending the older one.
 * The fix must not break this.
 */
static void
test_reliable_purge_legitimate_ack(void **state)
{
    (void)state;
 
    struct reliable *rel = test_reliable_new();
 
    struct reliable_entry *e0 = &rel->array[0];
    e0->active = true;
    e0->packet_id = 1;
 
    struct reliable_entry *e1 = &rel->array[1];
    e1->active = true;
    e1->packet_id = 2;
 
    rel->packet_id = 3; /* pids 0,1,2 sent; 1 and 2 still waiting */
 
    struct reliable_ack ack = { .len = 1, .packet_id = { 2 } };
    reliable_send_purge(rel, &ack);
 
    /* packet 2 was acked, so it is dropped */
    assert_false(e1->active);
    /* packet 1 is older, so it gets one ACK towards an early resend */
    assert_int_equal(e0->n_acks, 1);
    /* packet 1 was not acked, so it stays */
    assert_true(e0->active);
 
    reliable_free(rel);
}
 
int
main(void)
{
    openvpn_unit_test_setup();
    const struct CMUnitTest tests[] = {
        cmocka_unit_test_setup_teardown(test_packet_id_write_short, test_packet_id_write_setup,
                                        test_packet_id_write_teardown),
        cmocka_unit_test_setup_teardown(test_packet_id_write_long, test_packet_id_write_setup,
                                        test_packet_id_write_teardown),
        cmocka_unit_test_setup_teardown(test_packet_id_write_short_prepend,
                                        test_packet_id_write_setup, test_packet_id_write_teardown),
        cmocka_unit_test_setup_teardown(test_packet_id_write_long_prepend,
                                        test_packet_id_write_setup, test_packet_id_write_teardown),
        cmocka_unit_test_setup_teardown(test_packet_id_write_short_wrap, test_packet_id_write_setup,
                                        test_packet_id_write_teardown),
        cmocka_unit_test_setup_teardown(test_packet_id_write_long_wrap, test_packet_id_write_setup,
                                        test_packet_id_write_teardown),
        cmocka_unit_test_setup_teardown(test_packet_id_write_epoch, test_packet_id_write_setup,
                                        test_packet_id_write_teardown),
 
        cmocka_unit_test(test_get_num_output_sequenced_available),
        cmocka_unit_test(test_copy_acks_to_lru),
        cmocka_unit_test(test_packet_id_window),
        cmocka_unit_test(test_reliable_backoff_is_bounded),
        cmocka_unit_test(test_reliable_purge_ignores_forged_acks),
        cmocka_unit_test(test_reliable_purge_legitimate_ack)
 
    };
 
    return cmocka_run_group_tests_name("packet_id tests", tests, NULL, NULL);
}