#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <curl/curl.h>

/* dump curl result into a memory instead of FILE * */
struct curl_inmem
{
    char *memory;
    size_t size; /* size is used as an index */
};
typedef struct curl_inmem curl_inmem_t;

void dump_curlmem(void *data)
{
    curl_inmem_t *mem = (curl_inmem_t *) data;
    size_t iter = 0;
    while (iter < mem->size)
        putchar(mem->memory[iter++]);
}

size_t write_data(char *ptr, size_t size, size_t nmemb, void *userdata)
{
    size_t realsize = size * nmemb;
    curl_inmem_t *mem = (curl_inmem_t *) userdata;

    mem->memory = realloc(mem->memory, mem->size + realsize + 1);
    if (!mem->memory)
    {
        perror("failed to resize curl in memory");
        exit(EXIT_FAILURE);
    }

    memcpy(&(mem->memory[mem->size]), ptr, realsize);
    mem->size += realsize;
    mem->memory[mem->size] = 0;

    return realsize;
}

int main(int argc, char **argv)
{
    if (argc != 2)
    {
        fprintf(stderr, "usage: %s <url>\n", argv[0]);
        return 1;
    }

    CURL *curl_handle;
    CURLcode ret;

    curl_global_init(CURL_GLOBAL_ALL);
    curl_handle = curl_easy_init();
    if (curl_handle)
    {
        curl_easy_setopt(curl_handle, CURLOPT_URL, argv[1]);
        curl_easy_setopt(curl_handle, CURLOPT_HEADER, 1L);
        /* some servers don't like requests that are made without a user-agent
         * field, so we provide one */ 
        curl_easy_setopt(curl_handle, CURLOPT_USERAGENT, "libcurl-agent/1.0");
        char err_buff[CURL_ERROR_SIZE];
        curl_easy_setopt(curl_handle, CURLOPT_ERRORBUFFER, err_buff);

        /* by default passes NULL aka stdout */
        curl_inmem_t chunk = { 0, 0 };
        chunk.memory = (char *) malloc(sizeof(char));
        if (!chunk.memory)
            perror("failed to create a chunk");
        else
        {
            curl_easy_setopt(curl_handle, CURLOPT_WRITEDATA, (void *) &chunk);
            /* send all data to this function  */
            curl_easy_setopt(curl_handle, CURLOPT_WRITEFUNCTION, write_data);
        }

        if ((ret = curl_easy_perform(curl_handle)) != CURLE_OK)
            fprintf(stderr, "%s\n", err_buff);
        else
        {
            /* ask for the content-type */
            char *ct;
            ret = curl_easy_getinfo(curl_handle, CURLINFO_CONTENT_TYPE, &ct);
            if ((CURLE_OK == ret) && ct)
                printf("Content-Type: %s\n", ct);
        }

        /* print out */
        dump_curlmem(&chunk);

        /* always cleanup */
        curl_easy_cleanup(curl_handle);
        if (chunk.memory)
            free(chunk.memory);
        /* we're done with libcurl, so clean it up */ 
        curl_global_cleanup();
    }

    return 0;
}