path: root/test/helpers/noisydgrambio.c

/*
 * Copyright 2023 The OpenSSL Project Authors. All Rights Reserved.
 *
 * Licensed under the Apache License 2.0 (the "License").  You may not use
 * this file except in compliance with the License.  You can obtain a copy
 * in the file LICENSE in the source distribution or at
 * https://www.openssl.org/source/license.html
 */

#include <openssl/bio.h>
#include "quictestlib.h"
#include "../testutil.h"

#define MSG_DATA_LEN_MAX    1472
#define SAMPLING_WINDOW_PERIOD 10 /* in milliseconds */
#define MAX_PKTS_PER_WINDOW 1024

struct pkt_info_st {
    size_t size;
    OSSL_TIME timestamp;
};

struct bw_limiter_st {
    struct pkt_info_st pinfos[MAX_PKTS_PER_WINDOW]; /* ring buffer */
    size_t start, num;    /* ring buffer start and number of items */
    size_t size_sum;              /* sum of packet sizes in window */
    size_t bw;                            /* bandwidth in bytes/ms */
};

struct noisy_dgram_st {
    uint64_t this_dgram;
    BIO_MSG msg;
    uint64_t reinject_dgram;
    int backoff;
    int noise_rate;      /* 1 in noise_rate packets will get noise */
    struct bw_limiter_st recv_limit, send_limit;
    OSSL_TIME (*now_cb)(void *arg);
    void *now_cb_arg;
};

static long noisy_dgram_ctrl(BIO *bio, int cmd, long num, void *ptr)
{
    long ret;
    BIO *next = BIO_next(bio);

    if (next == NULL)
        return 0;

    switch (cmd) {
    case BIO_CTRL_DUP:
        ret = 0L;
        break;
    case BIO_CTRL_NOISE_BACK_OFF: {
            struct noisy_dgram_st *data;

            data = BIO_get_data(bio);
            if (!TEST_ptr(data))
                return 0;
            data->backoff = 1;
            ret = 1;
            break;
        }
    case BIO_CTRL_NOISE_RATE: {
            struct noisy_dgram_st *data;

            data = BIO_get_data(bio);
            if (!TEST_ptr(data))
                return 0;
            data->noise_rate = (int)num;
            ret = 1;
            break;
        }
    case BIO_CTRL_NOISE_RECV_BANDWIDTH: {
            struct noisy_dgram_st *data;

            data = BIO_get_data(bio);
            if (!TEST_ptr(data))
                return 0;
            data->recv_limit.bw = (size_t)num;
            ret = 1;
            break;
        }
    case BIO_CTRL_NOISE_SEND_BANDWIDTH: {
            struct noisy_dgram_st *data;

            data = BIO_get_data(bio);
            if (!TEST_ptr(data))
                return 0;
            data->send_limit.bw = (size_t)num;
            ret = 1;
            break;
        }
    case BIO_CTRL_NOISE_SET_NOW_CB: {
            struct noisy_dgram_st *data;
            struct bio_noise_now_cb_st *now_cb = ptr;

            data = BIO_get_data(bio);
            if (!TEST_ptr(data))
                return 0;
            data->now_cb = now_cb->now_cb;
            data->now_cb_arg = now_cb->now_cb_arg;
            ret = 1;
            break;
        }
    default:
        ret = BIO_ctrl(next, cmd, num, ptr);
        break;
    }
    return ret;
}

static size_t bandwidth_limit(struct bw_limiter_st *limit, OSSL_TIME now,
                              BIO_MSG *msg, size_t num_msg)
{
    size_t i;
    OSSL_TIME sampling_start
        = ossl_time_subtract(now, ossl_ms2time(SAMPLING_WINDOW_PERIOD));

    if (limit->bw == 0) /* 0 -> no limit */
        return num_msg;

    if (num_msg > MAX_PKTS_PER_WINDOW)
        num_msg = MAX_PKTS_PER_WINDOW;

    /* trim the start of the ring buffer */
    for (i = 0; i < limit->num; i++) {
        size_t idx = (limit->start + i) % MAX_PKTS_PER_WINDOW;

        if (ossl_time_compare(limit->pinfos[idx].timestamp, sampling_start) >= 0)
            break;
        limit->size_sum -= limit->pinfos[idx].size;
    }
    limit->start = (limit->start + i) % MAX_PKTS_PER_WINDOW;
    limit->num -= i;

    for (i = 0; i < num_msg; ++i) {
         size_t end;
         size_t pktsize = msg[i].data_len;

         if ((limit->size_sum + pktsize) / SAMPLING_WINDOW_PERIOD > limit->bw) {
             /*
              * Throw out all the packets once reaching the limit,
              * although some following packets could still fit.
              * This is accurate enough.
              */
#ifdef OSSL_NOISY_DGRAM_DEBUG
             printf("**BW limit applied: now: %llu orig packets %u new packets %u\n",
                    (unsigned long long)ossl_time2ms(now),
                    (unsigned int)num_msg, (unsigned int) i);
#endif
             num_msg = i;
             break;
         }

         if (limit->num >= MAX_PKTS_PER_WINDOW) {
             limit->size_sum -= limit->pinfos[limit->start].size;
             limit->start = (limit->start + 1) % MAX_PKTS_PER_WINDOW;
         } else {
           ++limit->num;
         }
         end = (limit->start + limit->num) % MAX_PKTS_PER_WINDOW;
         limit->pinfos[end].size = pktsize;
         limit->pinfos[end].timestamp = now;
         limit->size_sum += pktsize;
    }
    return num_msg;
}

static int noisy_dgram_sendmmsg(BIO *bio, BIO_MSG *msg, size_t stride,
                                size_t num_msg, uint64_t flags,
                                size_t *msgs_processed)
{
    BIO *next = BIO_next(bio);
    struct noisy_dgram_st *data;
    OSSL_TIME now;

    if (next == NULL)
        return 0;

    data = BIO_get_data(bio);
    if (!TEST_ptr(data))
        return 0;

    now = data->now_cb != NULL ? data->now_cb(data->now_cb_arg)
                               : ossl_time_now();

    /* bandwidth limit can be applied on both sides */
    num_msg = bandwidth_limit(&data->send_limit, now, msg, num_msg);
    if (num_msg == 0) {
        *msgs_processed = 0;
        ERR_raise(ERR_LIB_BIO, BIO_R_NON_FATAL);
        return 0;
    }

    /*
     * We only introduce noise when receiving messages. We just pass this on
     * to the underlying BIO.
     */
    return BIO_sendmmsg(next, msg, stride, num_msg, flags, msgs_processed);
}

/* Default noise_rate value. With a value of 5 that is 20% packets. */
#define NOISE_RATE  5

/*
 * We have 3 different types of noise: drop, duplicate and delay
 * Each of these have equal probability.
 */
#define NOISE_TYPE_DROP      0
#define NOISE_TYPE_DUPLICATE 1
#define NOISE_TYPE_DELAY     2
#define NOISE_TYPE_BITFLIPS  3
#define NUM_NOISE_TYPES      4

/*
 * When a duplicate occurs we reinject the new datagram after up to
 * MAX_DGRAM_REINJECT datagrams have been sent. A reinject of 1 means that the
 * duplicate follows immediately after the original datagram. A reinject of 4
 * means that original datagram plus 3 other datagrams are sent before the
 * reinjected datagram is inserted.
 * This also controls when a delay (not a duplicate) occurs. In that case
 * we add 1 to the number because there is no point in skipping the current
 * datagram only to immediately reinject it in the next datagram.
 */