/*
 * Copyright 2019-2021 OARC, Inc.
 * Copyright 2017-2018 Akamai Technologies
 * Copyright 2006-2016 Nominum, Inc.
 * All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/***
 ***	DNS Performance Testing Tool
 ***/

#include "config.h"

#include "net.h"
#include "datafile.h"
#include "dns.h"
#include "log.h"
#include "opt.h"
#include "os.h"
#include "util.h"
#include "list.h"
#include "buffer.h"

#include <inttypes.h>
#include <errno.h>
#include <math.h>
#include <pthread.h>
#include <signal.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
#include <sys/time.h>
#include <openssl/ssl.h>
#include <openssl/conf.h>
#include <openssl/err.h>

#define DEFAULT_SERVER_NAME "127.0.0.1"
#define DEFAULT_SERVER_PORT 53
#define DEFAULT_SERVER_TLS_PORT 853
#define DEFAULT_SERVER_PORTS "udp/tcp 53 or dot/tls 853"
#define DEFAULT_LOCAL_PORT 0
#define DEFAULT_MAX_OUTSTANDING 100
#define DEFAULT_TIMEOUT 5

#define TIMEOUT_CHECK_TIME 100000

#define MAX_INPUT_DATA (64 * 1024)

#define MAX_SOCKETS 256

#define RECV_BATCH_SIZE 16

typedef struct {
    int                argc;
    char**             argv;
    int                family;
    uint32_t           clients;
    uint32_t           threads;
    uint32_t           maxruns;
    uint64_t           timelimit;
    perf_sockaddr_t    server_addr;
    perf_sockaddr_t    local_addr;
    uint64_t           timeout;
    uint32_t           bufsize;
    bool               edns;
    bool               dnssec;
    perf_tsigkey_t*    tsigkey;
    perf_ednsoption_t* edns_option;
    uint32_t           max_outstanding;
    uint32_t           max_qps;
    uint64_t           stats_interval;
    bool               updates;
    bool               verbose;
    enum perf_net_mode mode;
} config_t;

typedef struct {
    uint64_t        start_time;
    uint64_t        end_time;
    uint64_t        stop_time;
    struct timespec stop_time_ns;
} times_t;

typedef struct {
    uint64_t rcodecounts[16];

    uint64_t num_sent;
    uint64_t num_interrupted;
    uint64_t num_timedout;
    uint64_t num_completed;

    uint64_t total_request_size;
    uint64_t total_response_size;

    uint64_t latency_sum;
    uint64_t latency_sum_squares;
    uint64_t latency_min;
    uint64_t latency_max;
} stats_t;

typedef perf_list(struct query_info) query_list;

typedef struct query_info {
    uint64_t                timestamp;
    query_list*             list;
    char*                   desc;
    struct perf_net_socket* sock;
    /*
     * This link links the query into the list of outstanding
     * queries or the list of available query IDs.
     */
    perf_link(struct query_info);
} query_info;

#define NQIDS 65536

typedef struct {
    query_info queries[NQIDS];
    query_list outstanding_queries;
    query_list unused_queries;

    pthread_t sender;
    pthread_t receiver;

    pthread_mutex_t lock;
    pthread_cond_t  cond;

    unsigned int            nsocks;
    int                     current_sock;
    struct perf_net_socket* socks;

    bool     done_sending;
    uint64_t done_send_time;

    const config_t* config;
    const times_t*  times;
    stats_t         stats;

    uint32_t max_outstanding;
    uint32_t max_qps;

    uint64_t last_recv;
} threadinfo_t;

static threadinfo_t* threads;

static pthread_mutex_t start_lock = PTHREAD_MUTEX_INITIALIZER;
static pthread_cond_t  start_cond = PTHREAD_COND_INITIALIZER;
static bool            started;

static bool interrupted = false;

static int threadpipe[2];
static int mainpipe[2];
static int intrpipe[2];

static perf_datafile_t* input;

const char* progname = "dnsperf";

static void
handle_sigint(int sig)
{
    (void)sig;
    if (write(intrpipe[1], "", 1)) { // lgtm [cpp/empty-block]
    }
}

static void
print_initial_status(const config_t* config)
{
    time_t now;
    char   buf[255], ct[32];
    int    i;

    printf("[Status] Command line: %s", progname);
    for (i = 1; i < config->argc; i++)
        printf(" %s", config->argv[i]);
    printf("\n");

    perf_sockaddr_format(&config->server_addr, buf, sizeof(buf));
    printf("[Status] Sending %s (to %s)\n",
        config->updates ? "updates" : "queries", buf);

    now = time(NULL);
    printf("[Status] Started at: %s", ctime_r(&now, ct));

    printf("[Status] Stopping after ");
    if (config->timelimit)
        printf("%u.%06u seconds",
            (unsigned int)(config->timelimit / MILLION),
            (unsigned int)(config->timelimit % MILLION));
    if (config->timelimit && config->maxruns)
        printf(" or ");
    if (config->maxruns)
        printf("%u run%s through file", config->maxruns,
            config->maxruns == 1 ? "" : "s");
    printf("\n");
}

static void
print_final_status(const config_t* config)
{
    const char* reason;

    if (interrupted)
        reason = "interruption";
    else if (config->maxruns > 0 && perf_datafile_nruns(input) == config->maxruns)
        reason = "end of file";
    else
        reason = "time limit";

    printf("[Status] Testing complete (%s)\n", reason);
    printf("\n");
}

static double
stddev(uint64_t sum_of_squares, uint64_t sum, uint64_t total)
{
    double squared;

    squared = (double)sum * (double)sum;
    return sqrt((sum_of_squares - (squared / total)) / (total - 1));
}

static void
print_statistics(const config_t* config, const times_t* times, stats_t* stats)
{
    const char*  units;
    uint64_t     run_time;
    bool         first_rcode;
    uint64_t     latency_avg;
    unsigned int i;

    units = config->updates ? "Updates" : "Queries";

    run_time = times->end_time - times->start_time;

    printf("Statistics:\n\n");

    printf("  %s sent:         %" PRIu64 "\n",
        units, stats->num_sent);
    printf("  %s completed:    %" PRIu64 " (%.2lf%%)\n",
        units, stats->num_completed,
        PERF_SAFE_DIV(100.0 * stats->num_completed, stats->num_sent));
    printf("  %s lost:         %" PRIu64 " (%.2lf%%)\n",
        units, stats->num_timedout,
        PERF_SAFE_DIV(100.0 * stats->num_timedout, stats->num_sent));
    if (stats->num_interrupted > 0)
        printf("  %s interrupted:  %" PRIu64 " (%.2lf%%)\n",
            units, stats->num_interrupted,
            PERF_SAFE_DIV(100.0 * stats->num_interrupted, stats->num_sent));
    printf("\n");

    printf("  Response codes:       ");
    first_rcode = true;
    for (i = 0; i < 16; i++) {
        if (stats->rcodecounts[i] == 0)
            continue;
        if (first_rcode)
            first_rcode = false;
        else
            printf(", ");
        printf("%s %" PRIu64 " (%.2lf%%)",
            perf_dns_rcode_strings[i], stats->rcodecounts[i],
            (stats->rcodecounts[i] * 100.0) / stats->num_completed);
    }
    printf("\n");

    printf("  Average packet size:  request %u, response %u\n",
        (unsigned int)PERF_SAFE_DIV(stats->total_request_size, stats->num_sent),
        (unsigned int)PERF_SAFE_DIV(stats->total_response_size,
            stats->num_completed));
    printf("  Run time (s):         %u.%06u\n",
        (unsigned int)(run_time / MILLION),
        (unsigned int)(run_time % MILLION));
    printf("  %s per second:   %.6lf\n", units,
        PERF_SAFE_DIV(stats->num_completed, (((double)run_time) / MILLION)));

    printf("\n");

    latency_avg = PERF_SAFE_DIV(stats->latency_sum, stats->num_completed);
    printf("  Average Latency (s):  %u.%06u (min %u.%06u, max %u.%06u)\n",
        (unsigned int)(latency_avg / MILLION),
        (unsigned int)(latency_avg % MILLION),
        (unsigned int)(stats->latency_min / MILLION),
        (unsigned int)(stats->latency_min % MILLION),
        (unsigned int)(stats->latency_max / MILLION),
        (unsigned int)(stats->latency_max % MILLION));
    if (stats->num_completed > 1) {
        printf("  Latency StdDev (s):   %f\n",
            stddev(stats->latency_sum_squares, stats->latency_sum,
                stats->num_completed)
                / MILLION);
    }

    printf("\n");
}

static void
sum_stats(const config_t* config, stats_t* total)
{
    unsigned int i, j;

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

    for (i = 0; i < config->threads; i++) {
        stats_t* stats = &threads[i].stats;

        for (j = 0; j < 16; j++)
            total->rcodecounts[j] += stats->rcodecounts[j];

        total->num_sent += stats->num_sent;
        total->num_interrupted += stats->num_interrupted;
        total->num_timedout += stats->num_timedout;
        total->num_completed += stats->num_completed;

        total->total_request_size += stats->total_request_size;
        total->total_response_size += stats->total_response_size;

        total->latency_sum += stats->latency_sum;
        total->latency_sum_squares += stats->latency_sum_squares;
        if (stats->latency_min < total->latency_min || i == 0)
            total->latency_min = stats->latency_min;
        if (stats->latency_max > total->latency_max)
            total->latency_max = stats->latency_max;
    }
}

static char*
stringify(unsigned int value)
{
    static char buf[20];

    snprintf(buf, sizeof(buf), "%u", value);
    return buf;
}

static void
setup(int argc, char** argv, config_t* config)
{
    const char* family      = NULL;
    const char* server_name = DEFAULT_SERVER_NAME;
    in_port_t   server_port = 0;
    const char* local_name  = NULL;
    in_port_t   local_port  = DEFAULT_LOCAL_PORT;
    const char* filename    = NULL;
    const char* edns_option = NULL;
    const char* tsigkey     = NULL;
    const char* mode        = 0;

    memset(config, 0, sizeof(*config));
    config->argc = argc;
    config->argv = argv;

    config->family          = AF_UNSPEC;
    config->clients         = 1;
    config->threads         = 1;
    config->timeout         = DEFAULT_TIMEOUT * MILLION;
    config->max_outstanding = DEFAULT_MAX_OUTSTANDING;
    config->mode            = sock_udp;

    perf_opt_add('f', perf_opt_string, "family",
        "address family of DNS transport, inet or inet6", "any",
        &family);
    perf_opt_add('m', perf_opt_string, "mode", "set transport mode: udp, tcp or dot/tls", "udp", &mode);
    perf_opt_add('s', perf_opt_string, "server_addr",
        "the server to query", DEFAULT_SERVER_NAME, &server_name);
    perf_opt_add('p', perf_opt_port, "port",
        "the port on which to query the server",
        DEFAULT_SERVER_PORTS, &server_port);
    perf_opt_add('a', perf_opt_string, "local_addr",
        "the local address from which to send queries", NULL,
        &local_name);
    perf_opt_add('x', perf_opt_port, "local_port",
        "the local port from which to send queries",
        stringify(DEFAULT_LOCAL_PORT), &local_port);
    perf_opt_add('d', perf_opt_string, "datafile",
        "the input data file", "stdin", &filename);
    perf_opt_add('c', perf_opt_uint, "clients",
        "the number of clients to act as", NULL,
        &config->clients);
    perf_opt_add('T', perf_opt_uint, "threads",
        "the number of threads to run", NULL,
        &config->threads);
    perf_opt_add('n', perf_opt_uint, "maxruns",
        "run through input at most N times", NULL,
        &config->maxruns);
    perf_opt_add('l', perf_opt_timeval, "timelimit",
        "run for at most this many seconds", NULL,
        &config->timelimit);
    perf_opt_add('b', perf_opt_uint, "buffer_size",
        "socket send/receive buffer size in kilobytes", NULL,
        &config->bufsize);
    perf_opt_add('t', perf_opt_timeval, "timeout",
        "the timeout for query completion in seconds",
        stringify(DEFAULT_TIMEOUT), &config->timeout);
    perf_opt_add('e', perf_opt_boolean, NULL,
        "enable EDNS 0", NULL, &config->edns);
    perf_opt_add('E', perf_opt_string, "code:value",
        "send EDNS option", NULL, &edns_option);
    perf_opt_add('D', perf_opt_boolean, NULL,
        "set the DNSSEC OK bit (implies EDNS)", NULL,
        &config->dnssec);
    perf_opt_add('y', perf_opt_string, "[alg:]name:secret",
        "the TSIG algorithm, name and secret (base64)", NULL,
        &tsigkey);
    perf_opt_add('q', perf_opt_uint, "num_queries",
        "the maximum number of queries outstanding",
        stringify(DEFAULT_MAX_OUTSTANDING),
        &config->max_outstanding);
    perf_opt_add('Q', perf_opt_uint, "max_qps",
        "limit the number of queries per second", NULL,
        &config->max_qps);
    perf_opt_add('S', perf_opt_timeval, "stats_interval",
        "print qps statistics every N seconds",
        NULL, &config->stats_interval);
    perf_opt_add('u', perf_opt_boolean, NULL,
        "send dynamic updates instead of queries",
        NULL, &config->updates);
    perf_opt_add('v', perf_opt_boolean, NULL,
        "verbose: report each query and additional information to stdout",
        NULL, &config->verbose);
    bool log_stdout = false;
    perf_opt_add('W', perf_opt_boolean, NULL, "log warnings and errors to stdout instead of stderr", NULL, &log_stdout);

    perf_opt_parse(argc, argv);

    if (log_stdout) {
        perf_log_tostdout();
    }

    if (mode != 0)
        config->mode = perf_net_parsemode(mode);

    if (!server_port) {
        server_port = config->mode == sock_tls ? DEFAULT_SERVER_TLS_PORT : DEFAULT_SERVER_PORT;
    }

    if (family != NULL)
        config->family = perf_net_parsefamily(family);
    perf_net_parseserver(config->family, server_name, server_port,
        &config->server_addr);
    perf_net_parselocal(config->server_addr.sa.sa.sa_family,
        local_name, local_port, &config->local_addr);

    input = perf_datafile_open(filename);

    if (config->maxruns == 0 && config->timelimit == 0)
        config->maxruns = 1;
    perf_datafile_setmaxruns(input, config->maxruns);

    if (config->dnssec || edns_option != NULL)
        config->edns = true;

    if (tsigkey != NULL)
        config->tsigkey = perf_tsig_parsekey(tsigkey);

    if (edns_option != NULL)
        config->edns_option = perf_edns_parseoption(edns_option);

    /*
     * If we run more threads than max-qps, some threads will have
     * ->max_qps set to 0, and be unlimited.
     */
    if (config->max_qps > 0 && config->threads > config->max_qps)
        config->threads = config->max_qps;

    /*
     * We also can't run more threads than clients.
     */
    if (config->threads > config->clients)
        config->threads = config->clients;

#ifndef HAVE_LDNS
    if (config->updates) {
        perf_log_fatal("Unable to dynamic update, support not built in");
    }
#endif
}

static void
cleanup(config_t* config)
{
    unsigned int i;

    perf_datafile_close(&input);
    for (i = 0; i < 2; i++) {
        close(threadpipe[i]);
        close(mainpipe[i]);
        close(intrpipe[i]);
    }
    if (config->tsigkey != NULL)
        perf_tsig_destroykey(&config->tsigkey);
    if (config->edns_option != NULL)
        perf_edns_destroyoption(&config->edns_option);
}

typedef enum {
    prepend_unused,
    append_unused,
    prepend_outstanding,
} query_move_op;

static inline void
query_move(threadinfo_t* tinfo, query_info* q, query_move_op op)
{
    perf_list_unlink(*q->list, q);
    switch (op) {
    case prepend_unused:
        q->list = &tinfo->unused_queries;
        perf_list_prepend(tinfo->unused_queries, q);
        break;
    case append_unused:
        q->list = &tinfo->unused_queries;
        perf_list_append(tinfo->unused_queries, q);
        break;
    case prepend_outstanding:
        q->list = &tinfo->outstanding_queries;
        perf_list_prepend(tinfo->outstanding_queries, q);
        break;
    }
}

static inline uint64_t
num_outstanding(const stats_t* stats)
{
    return stats->num_sent - stats->num_completed - stats->num_timedout;
}

static void
wait_for_start(void)
{
    PERF_LOCK(&start_lock);
    while (!started)
        PERF_WAIT(&start_cond, &start_lock);
    PERF_UNLOCK(&start_lock);
}

static void*
do_send(void* arg)
{
    threadinfo_t*   tinfo;
    const config_t* config;
    const times_t*  times;
    stats_t*        stats;
    unsigned int    max_packet_size;
    perf_buffer_t   msg;
    uint64_t        now, run_time, req_time;
    char            input_data[MAX_INPUT_DATA];
    perf_buffer_t   lines;
    perf_region_t   used;
    query_info*     q;
    int             qid;
    unsigned char   packet_buffer[MAX_EDNS_PACKET];
    unsigned char*  base;
    unsigned int    length;
    int             n, i, any_inprogress = 0;
    perf_result_t   result;

    tinfo           = (threadinfo_t*)arg;
    config          = tinfo->config;
    times           = tinfo->times;
    stats           = &tinfo->stats;
    max_packet_size = config->edns ? MAX_EDNS_PACKET : MAX_UDP_PACKET;
    perf_buffer_init(&msg, packet_buffer, max_packet_size);
    perf_buffer_init(&lines, input_data, sizeof(input_data));

    wait_for_start();
    now = perf_get_time();
    while (!interrupted && now < times->stop_time) {
        /* Avoid flooding the network too quickly. */
        if (stats->num_sent < tinfo->max_outstanding && stats->num_sent % 2 == 1) {
            if (stats->num_completed == 0)
                usleep(1000);
            else
                sleep(0);
            now = perf_get_time();
        }

        /* Rate limiting */
        if (tinfo->max_qps > 0) {
            run_time = now - times->start_time;
            req_time = (MILLION * stats->num_sent) / tinfo->max_qps;
            if (req_time > run_time) {
                usleep(req_time - run_time);
                now = perf_get_time();
                continue;
            }
        }

        PERF_LOCK(&tinfo->lock);

        /* Limit in-flight queries */
        if (num_outstanding(stats) >= tinfo->max_outstanding) {
            PERF_TIMEDWAIT(&tinfo->cond, &tinfo->lock, &times->stop_time_ns, NULL);
            PERF_UNLOCK(&tinfo->lock);
            now = perf_get_time();
            continue;
        }

        q = perf_list_head(tinfo->unused_queries);
        query_move(tinfo, q, prepend_outstanding);
        q->timestamp = UINT64_MAX;

        i = tinfo->nsocks * 2;
        while (i--) {
            q->sock = &tinfo->socks[tinfo->current_sock++ % tinfo->nsocks];
            switch (perf_net_sockready(q->sock, threadpipe[0], TIMEOUT_CHECK_TIME)) {
            case 0:
                if (config->verbose) {
                    perf_log_warning("socket %p not ready", q->sock);
                }
                q->sock = 0;
                continue;
            case -1:
                if (errno == EINPROGRESS) {
                    any_inprogress = 1;
                    q->sock        = 0;
                    continue;
                }
                if (config->verbose) {
                    perf_log_warning("socket %p readiness check timed out", q->sock);
                }
            default:
                break;
            }
            break;
        };

        if (!q->sock) {
            query_move(tinfo, q, prepend_unused);
            PERF_UNLOCK(&tinfo->lock);
            now = perf_get_time();
            continue;
        }
        PERF_UNLOCK(&tinfo->lock);

        perf_buffer_clear(&lines);
        result = perf_datafile_next(input, &lines, config->updates);
        if (result != PERF_R_SUCCESS) {
            if (result == PERF_R_INVALIDFILE)
                perf_log_fatal("input file contains no data");
            break;
        }

        qid = q - tinfo->queries;
        perf_buffer_usedregion(&lines, &used);
        perf_buffer_clear(&msg);
        result = perf_dns_buildrequest(&used, qid,
            config->edns, config->dnssec, config->updates,
            config->tsigkey, config->edns_option,
            &msg);
        if (result != PERF_R_SUCCESS) {
            PERF_LOCK(&tinfo->lock);
            query_move(tinfo, q, prepend_unused);
            PERF_UNLOCK(&tinfo->lock);
            now = perf_get_time();
            continue;
        }

        base   = perf_buffer_base(&msg);
        length = perf_buffer_usedlength(&msg);

        now = perf_get_time();
        if (config->verbose) {
            free(q->desc);
            q->desc = strdup(lines.base);
            if (q->desc == NULL)
                perf_log_fatal("out of memory");
        }
        q->timestamp = now;

        n = perf_net_sendto(q->sock, base, length, 0, &config->server_addr.sa.sa,
            config->server_addr.length);
        if (n < 0) {
            if (errno == EINPROGRESS) {
                if (config->verbose) {
                    perf_log_warning("network congested, packet sending in progress");
                }
                any_inprogress = 1;
            } else {
                if (config->verbose) {
                    char __s[256];
                    perf_log_warning("failed to send packet: %s", perf_strerror_r(errno, __s, sizeof(__s)));
                }
                PERF_LOCK(&tinfo->lock);
                query_move(tinfo, q, prepend_unused);
                PERF_UNLOCK(&tinfo->lock);
                continue;
            }
        } else if ((unsigned int)n != length) {
            perf_log_warning("failed to send full packet: only sent %d of %u", n, length);
            PERF_LOCK(&tinfo->lock);
            query_move(tinfo, q, prepend_unused);
            PERF_UNLOCK(&tinfo->lock);
            continue;
        }
        stats->num_sent++;

        stats->total_request_size += length;
    }

    while (any_inprogress) {
        any_inprogress = 0;
        for (i = 0; i < tinfo->nsocks; i++) {
            if (perf_net_sockready(&tinfo->socks[i], threadpipe[0], TIMEOUT_CHECK_TIME) == -1 && errno == EINPROGRESS) {
                any_inprogress = 1;
            }
        }
    }

    tinfo->done_send_time = perf_get_time();
    tinfo->done_sending   = true;
    if (write(mainpipe[1], "", 1)) { // lgtm [cpp/empty-block]
    }
    return NULL;
}

static void
process_timeouts(threadinfo_t* tinfo, uint64_t now)
{
    struct query_info* q;
    const config_t*    config;

    config = tinfo->config;

    /* Avoid locking unless we need to. */
    q = perf_list_tail(tinfo->outstanding_queries);
    if (q == NULL || q->timestamp > now || now - q->timestamp < config->timeout)
        return;

    PERF_LOCK(&tinfo->lock);

    do {
        query_move(tinfo, q, append_unused);

        tinfo->stats.num_timedout++;

        if (q->desc != NULL) {
            perf_log_printf("> T %s", q->desc);
        } else {
            perf_log_printf("[Timeout] %s timed out: msg id %u",
                config->updates ? "Update" : "Query",
                (unsigned int)(q - tinfo->queries));
        }
        q = perf_list_tail(tinfo->outstanding_queries);
    } while (q != NULL && q->timestamp < now && now - q->timestamp >= config->timeout);

    PERF_UNLOCK(&tinfo->lock);
}

typedef struct {
    struct perf_net_socket* sock;
    uint16_t                qid;
    uint16_t                rcode;
    unsigned int            size;
    uint64_t                when;
    uint64_t                sent;
    bool                    unexpected;
    bool                    short_response;
    char*                   desc;
} received_query_t;

static bool
recv_one(threadinfo_t* tinfo, int which_sock,
    unsigned char* packet_buffer, unsigned int packet_size,
    received_query_t* recvd, int* saved_errnop)
{
    uint16_t* packet_header;
    uint64_t  now;
    int       n;

    packet_header = (uint16_t*)packet_buffer;

    n   = perf_net_recv(&tinfo->socks[which_sock], packet_buffer, packet_size, 0);
    now = perf_get_time();
    if (n < 0) {
        *saved_errnop = errno;
        return false;
    }
    if (!n) {
        // Treat connection closed like try again until reconnection features are in
        *saved_errnop = EAGAIN;
        return false;
    }
    recvd->sock           = &tinfo->socks[which_sock];
    recvd->qid            = ntohs(packet_header[0]);
    recvd->rcode          = ntohs(packet_header[1]) & 0xF;
    recvd->size           = n;
    recvd->when           = now;
    recvd->sent           = 0;
    recvd->unexpected     = false;
    recvd->short_response = (n < 4);
    recvd->desc           = NULL;
    return true;
}

static inline void
bit_set(unsigned char* bits, unsigned int bit)
{
    unsigned int shift, mask;

    shift = 7 - (bit % 8);
    mask  = 1 << shift;

    bits[bit / 8] |= mask;
}

static inline bool
bit_check(unsigned char* bits, unsigned int bit)
{
    unsigned int shift;

    shift = 7 - (bit % 8);

    if ((bits[bit / 8] >> shift) & 0x01)
        return true;
    return false;
}

static void*
do_recv(void* arg)
{
    threadinfo_t*    tinfo;
    stats_t*         stats;
    unsigned char    packet_buffer[MAX_EDNS_PACKET];
    received_query_t recvd[RECV_BATCH_SIZE] = { { 0, 0, 0, 0, 0, 0, false, false, 0 } };
    unsigned int     nrecvd;
    int              saved_errno;
    unsigned char    socketbits[MAX_SOCKETS / 8];
    uint64_t         now, latency;
    query_info*      q;
    unsigned int     current_socket, last_socket;
    unsigned int     i, j;

    tinfo = (threadinfo_t*)arg;
    stats = &tinfo->stats;

    wait_for_start();
    now         = perf_get_time();
    last_socket = 0;
    while (!interrupted) {
        process_timeouts(tinfo, now);

        /*
         * If we're done sending and either all responses have been
         * received, stop.
         */
        if (tinfo->done_sending && num_outstanding(stats) == 0)
            break;

        /*
         * Try to receive a few packets, so that we can process them
         * atomically.
         */
        saved_errno = 0;
        memset(socketbits, 0, sizeof(socketbits));
        for (i = 0; i < RECV_BATCH_SIZE; i++) {
            for (j = 0; j < tinfo->nsocks; j++) {
                current_socket = (j + last_socket) % tinfo->nsocks;
                if (bit_check(socketbits, current_socket))
                    continue;
                if (recv_one(tinfo, current_socket, packet_buffer,
                        sizeof(packet_buffer), &recvd[i], &saved_errno)) {
                    last_socket = (current_socket + 1);
                    break;
                }
                bit_set(socketbits, current_socket);
                if (saved_errno != EAGAIN)
                    break;
            }
            if (j == tinfo->nsocks)
                break;
        }
        nrecvd = i;

        /* Do all of the processing that requires the lock */
        PERF_LOCK(&tinfo->lock);
        for (i = 0; i < nrecvd; i++) {
            if (recvd[i].short_response)
                continue;

            q = &tinfo->queries[recvd[i].qid];
            if (q->list != &tinfo->outstanding_queries || q->timestamp == UINT64_MAX || !perf_net_sockeq(q->sock, recvd[i].sock)) {
                recvd[i].unexpected = true;
                continue;
            }
            query_move(tinfo, q, append_unused);
            recvd[i].sent = q->timestamp;
            recvd[i].desc = q->desc;
            q->desc       = NULL;
        }
        PERF_SIGNAL(&tinfo->cond);
        PERF_UNLOCK(&tinfo->lock);

        /* Now do the rest of the processing unlocked */
        for (i = 0; i < nrecvd; i++) {
            if (recvd[i].short_response) {
                perf_log_warning("received short response");
                continue;
            }
            if (recvd[i].unexpected) {
                perf_log_warning("received a response with an "
                                 "unexpected (maybe timed out) "
                                 "id: %u",
                    recvd[i].qid);
                continue;
            }
            latency = recvd[i].when - recvd[i].sent;
            if (recvd[i].desc != NULL) {
                perf_log_printf(
                    "> %s %s %u.%06u",
                    perf_dns_rcode_strings[recvd[i].rcode],
                    recvd[i].desc,
                    (unsigned int)(latency / MILLION),
                    (unsigned int)(latency % MILLION));
                free(recvd[i].desc);
            }

            stats->num_completed++;
            stats->total_response_size += recvd[i].size;
            stats->rcodecounts[recvd[i].rcode]++;
            stats->latency_sum += latency;
            stats->latency_sum_squares += (latency * latency);
            if (latency < stats->latency_min || stats->num_completed == 1)
                stats->latency_min = latency;
            if (latency > stats->latency_max)
                stats->latency_max = latency;
        }

        if (nrecvd > 0)
            tinfo->last_recv = recvd[nrecvd - 1].when;

        /*
         * If there was an error, handle it (by either ignoring it,
         * blocking, or exiting).
         */
        if (nrecvd < RECV_BATCH_SIZE) {
            if (saved_errno == EINTR) {
                continue;
            } else if (saved_errno == EAGAIN) {
                perf_os_waituntilanyreadable(tinfo->socks, tinfo->nsocks,
                    threadpipe[0], TIMEOUT_CHECK_TIME);
                now = perf_get_time();
                continue;
            } else {
                char __s[256];
                perf_log_fatal("failed to receive packet: %s", perf_strerror_r(saved_errno, __s, sizeof(__s)));
            }
        }
    }

    return NULL;
}

static void*
do_interval_stats(void* arg)
{
    threadinfo_t*          tinfo;
    stats_t                total;
    uint64_t               now;
    uint64_t               last_interval_time;
    uint64_t               last_completed;
    uint64_t               interval_time;
    uint64_t               num_completed;
    double                 qps;
    struct perf_net_socket sock = { .mode = sock_pipe, .fd = threadpipe[0] };

    tinfo              = arg;
    last_interval_time = tinfo->times->start_time;
    last_completed     = 0;

    wait_for_start();
    while (perf_os_waituntilreadable(&sock, threadpipe[0],
               tinfo->config->stats_interval)
           == PERF_R_TIMEDOUT) {
        now = perf_get_time();
        sum_stats(tinfo->config, &total);
        interval_time = now - last_interval_time;
        num_completed = total.num_completed - last_completed;
        qps           = num_completed / (((double)interval_time) / MILLION);
        perf_log_printf("%u.%06u: %.6lf",
            (unsigned int)(now / MILLION),
            (unsigned int)(now % MILLION), qps);
        last_interval_time = now;
        last_completed     = total.num_completed;
    }

    return NULL;
}

static void
cancel_queries(threadinfo_t* tinfo)
{
    struct query_info* q;

    while (true) {
        q = perf_list_tail(tinfo->outstanding_queries);
        if (q == NULL)
            break;
        query_move(tinfo, q, append_unused);

        if (q->timestamp == UINT64_MAX)
            continue;

        tinfo->stats.num_interrupted++;
        if (q->desc != NULL) {
            perf_log_printf("> I %s", q->desc);
            free(q->desc);
            q->desc = NULL;
        }
    }
}

static uint32_t
per_thread(uint32_t total, uint32_t nthreads, unsigned int offset)
{
    uint32_t value, temp_total;

    value = total / nthreads;

    /*
     * work out if there's a shortfall and adjust if necessary
     */
    temp_total = value * nthreads;
    if (temp_total < total && offset < total - temp_total)
        value++;

    return value;
}

static void
threadinfo_init(threadinfo_t* tinfo, const config_t* config,
    const times_t* times)
{
    unsigned int offset, socket_offset, i;

    memset(tinfo, 0, sizeof(*tinfo));
    PERF_MUTEX_INIT(&tinfo->lock);
    PERF_COND_INIT(&tinfo->cond);

    perf_list_init(tinfo->outstanding_queries);
    perf_list_init(tinfo->unused_queries);
    for (i = 0; i < NQIDS; i++) {
        perf_link_init(&tinfo->queries[i]);
        perf_list_append(tinfo->unused_queries, &tinfo->queries[i]);
        tinfo->queries[i].list = &tinfo->unused_queries;
    }

    offset = tinfo - threads;

    tinfo->config = config;
    tinfo->times  = times;

    /*
     * Compute per-thread limits based on global values.
     */
    tinfo->max_outstanding = per_thread(config->max_outstanding,
        config->threads, offset);
    tinfo->max_qps         = per_thread(config->max_qps, config->threads, offset);
    tinfo->nsocks          = per_thread(config->clients, config->threads, offset);

    /*
     * We can't have more than 64k outstanding queries per thread.
     */
    if (tinfo->max_outstanding > NQIDS)
        tinfo->max_outstanding = NQIDS;

    if (tinfo->nsocks > MAX_SOCKETS)
        tinfo->nsocks = MAX_SOCKETS;

    if (!(tinfo->socks = calloc(tinfo->nsocks, sizeof(*tinfo->socks)))) {
        perf_log_fatal("out of memory");
    }
    socket_offset = 0;
    for (i = 0; i < offset; i++)
        socket_offset += threads[i].nsocks;
    for (i = 0; i < tinfo->nsocks; i++)
        tinfo->socks[i] = perf_net_opensocket(config->mode, &config->server_addr,
            &config->local_addr,
            socket_offset++,
            config->bufsize);
    tinfo->current_sock = 0;

    PERF_THREAD(&tinfo->receiver, do_recv, tinfo);
    PERF_THREAD(&tinfo->sender, do_send, tinfo);
}

static void
threadinfo_stop(threadinfo_t* tinfo)
{
    PERF_SIGNAL(&tinfo->cond);
    PERF_JOIN(tinfo->sender, NULL);
    PERF_JOIN(tinfo->receiver, NULL);
}

static void
threadinfo_cleanup(threadinfo_t* tinfo, times_t* times)
{
    unsigned int i;

    if (interrupted)
        cancel_queries(tinfo);
    for (i = 0; i < tinfo->nsocks; i++)
        perf_net_close(&tinfo->socks[i]);
    if (tinfo->last_recv > times->end_time)
        times->end_time = tinfo->last_recv;
}

int main(int argc, char** argv)
{
    config_t               config;
    times_t                times;
    stats_t                total_stats;
    threadinfo_t           stats_thread;
    unsigned int           i;
    perf_result_t          result;
    struct perf_net_socket sock = { .mode = sock_pipe };

    printf("DNS Performance Testing Tool\n"
           "Version " PACKAGE_VERSION "\n\n");

    (void)SSL_library_init();
#if OPENSSL_VERSION_NUMBER < 0x10100000L
    SSL_load_error_strings();
    OPENSSL_config(0);
#endif

    setup(argc, argv, &config);

    if (pipe(threadpipe) < 0 || pipe(mainpipe) < 0 || pipe(intrpipe) < 0)
        perf_log_fatal("creating pipe");

    perf_datafile_setpipefd(input, threadpipe[0]);

    perf_os_blocksignal(SIGINT, true);
    switch (config.mode) {
    case sock_tcp:
    case sock_tls:
        // block SIGPIPE for TCP/TLS mode, if connection is closed it will generate a signal
        perf_os_blocksignal(SIGPIPE, true);
        break;
    default:
        break;
    }

    print_initial_status(&config);

    if (!(threads = calloc(config.threads, sizeof(threadinfo_t)))) {
        perf_log_fatal("out of memory");
    }
    for (i = 0; i < config.threads; i++)
        threadinfo_init(&threads[i], &config, &times);
    if (config.stats_interval > 0) {
        stats_thread.config = &config;
        stats_thread.times  = &times;
        PERF_THREAD(&stats_thread.sender, do_interval_stats, &stats_thread);
    }

    times.start_time = perf_get_time();
    if (config.timelimit > 0)
        times.stop_time = times.start_time + config.timelimit;
    else
        times.stop_time = UINT64_MAX;
    times.stop_time_ns.tv_sec  = times.stop_time / MILLION;
    times.stop_time_ns.tv_nsec = (times.stop_time % MILLION) * 1000;

    PERF_LOCK(&start_lock);
    started = true;
    PERF_BROADCAST(&start_cond);
    PERF_UNLOCK(&start_lock);

    perf_os_handlesignal(SIGINT, handle_sigint);
    perf_os_blocksignal(SIGINT, false);
    sock.fd = mainpipe[0];
    result  = perf_os_waituntilreadable(&sock, intrpipe[0],
        times.stop_time - times.start_time);
    if (result == PERF_R_CANCELED)
        interrupted = true;

    times.end_time = perf_get_time();

    if (write(threadpipe[1], "", 1)) { // lgtm [cpp/empty-block]
    }
    for (i = 0; i < config.threads; i++)
        threadinfo_stop(&threads[i]);
    if (config.stats_interval > 0)
        PERF_JOIN(stats_thread.sender, NULL);

    for (i = 0; i < config.threads; i++)
        threadinfo_cleanup(&threads[i], &times);

    print_final_status(&config);

    sum_stats(&config, &total_stats);
    print_statistics(&config, &times, &total_stats);

    cleanup(&config);
#if OPENSSL_VERSION_NUMBER < 0x10100000L
    ERR_free_strings();
#endif

    return (0);
}
