#include <stdio.h>
#include <pthread.h>
#include <curl/curl.h>

#define NUMT 32

CURLSH *shdl[NUMT];

static pthread_mutex_t dnslock;

static void lock_cb(CURL *handle, curl_lock_data data,
        curl_lock_access access, void *userptr)
{
    (void)access; /* unused */
    (void)userptr; /* unused */
    (void)handle; /* unused */
    (void)data; /* unused */
    pthread_mutex_lock(&dnslock);
}

static void unlock_cb(CURL *handle, curl_lock_data data,
        void *userptr)
{
    (void)userptr; /* unused */
    (void)handle;  /* unused */
    (void)data;    /* unused */
    pthread_mutex_unlock(&dnslock);
}

size_t write_data(void *buffer, size_t size, size_t nmemb, void *userp)
{
    return size * nmemb;
}

static void *pull_one_url(void *arg)
{
    CURL *curl;
    int i = (int)arg;
    char buf[512];
    char buf2[512];
    char *ip;
    struct curl_slist *slist = NULL;

    curl = curl_easy_init();
    while (1) {
        if (i++ >= NUMT)
            i = 0;
        sprintf(buf, "http://foo:8080/127.0.0.%i", i);
        sprintf(buf2, "foo:8080:127.0.0.%i", i);
        slist = curl_slist_append(slist, buf2);
        curl_easy_reset(curl);
        curl_easy_setopt(curl, CURLOPT_SHARE, shdl[i]);
        curl_easy_setopt(curl, CURLOPT_URL, buf);
        curl_easy_setopt(curl, CURLOPT_RESOLVE, slist);
        curl_easy_setopt(curl, CURLOPT_DNS_CACHE_TIMEOUT, 0L);
        curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, write_data);

        curl_easy_perform(curl);

        curl_easy_setopt(curl, CURLOPT_SHARE, NULL);
        curl_slist_free_all(slist);
        slist = NULL;
        curl_easy_getinfo(curl, CURLINFO_PRIMARY_IP, &ip);
        printf("connected to %s for 127.0.0.%i\n", ip, i);
    }
    curl_easy_cleanup(curl);
    return NULL;
}

int main(int argc, char **argv)
{
    pthread_t tid[NUMT];
    int i;
    int error;

    curl_global_init(CURL_GLOBAL_ALL);
    pthread_mutex_init(&dnslock, NULL);

    for(i = 0; i< NUMT; i++) {
        shdl[i] = curl_share_init();
        curl_share_setopt(shdl[i], CURLSHOPT_SHARE, CURL_LOCK_DATA_DNS);
        curl_share_setopt(shdl[i], CURLSHOPT_LOCKFUNC, lock_cb);
        curl_share_setopt(shdl[i], CURLSHOPT_UNLOCKFUNC, unlock_cb);
    }
    for(i = 0; i< NUMT; i++) {
        pthread_create(&tid[i],
                NULL, /* default attributes please */
                pull_one_url,
                (void *)(i+1));
    }

    /* now wait for all threads to terminate */
    for(i = 0; i< NUMT; i++) {
        error = pthread_join(tid[i], NULL);
        fprintf(stderr, "Thread %d terminated\n", i);
    }
    return 0;
}