curl_pcap

curl_pcap.c

/**
* Take the URL of remote pcap from command line and download the file to disk
* It check if the extension is allowed (pcap-cap-pcapng)
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <curl/curl.h>

#define FILENAME_LEN 1000

size_t write_data_cb(void *ptr, size_t size, size_t nmemb, FILE *stream) {
    size_t written = fwrite(ptr, size, nmemb, stream);
    return written;
}

int check_extension(char *url, int len, char *ext) {
    if(url == NULL || len == 0)
        return -1;

    if(strstr(url, "pcap"))
    memcpy(ext, "pcap", 4);
    else if(strstr(url, "cap"))
        memcpy(ext, "cap", 3);
    else if(strstr(url, "pcapng"))
        memcpy(ext, "pcapng", 6);
    else
        return -1;
    
    return 0;
}

/* MAIN */
int main(int argc, char *argv[]) {
    
    CURL *curl;
    CURLcode res;
    FILE *fp;
    char filename[FILENAME_LEN] = {0}, ext[5] = {0};
    int ret, len = 0;
    /* NOTE: argv[0] is the program name */
    char *url = argv[1];
    
    len = strlen(url);

    /* check extension (pcap-cap-pcang) */
    ret = check_extension(url, len, ext);
    if(ret == -1) {
        fprintf(stderr, "Extension not allowed\n");
        exit(1);
    }
    
    /* give new name base on time */
    time_t t = time(NULL);
    struct tm tm = *localtime(&t);    
    snprintf(filename, FILENAME_LEN, "%d-%02d-%02d-%02d:%02d:%02d.%s",
             tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday, tm.tm_hour, tm.tm_min, tm.tm_sec, ext);
    
    /* INIT CURL */
    curl = curl_easy_init();
    
    if(curl) {
        fp = fopen(filename, "wb");
        if(fp == NULL) {
            fprintf(stderr, "Cannot open file\n");
            exit(1);
        }
        /* SETOPT */
        curl_easy_setopt(curl, CURLOPT_URL,           url);
        curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, write_data_cb);
        curl_easy_setopt(curl, CURLOPT_WRITEDATA,     fp);
        res = curl_easy_perform(curl);
        if(res != 0) {
            fprintf(stderr, "error on curl_easy_perform function\n");
            exit(1);
        }
        /* CLEANUP */
        curl_easy_cleanup(curl);
        fclose(fp);
    }
    return 0;
}