Authenticating libcurl FTP download in C++

Question

I am trying to upload a file using libcurl but it appears that it is not authenticating the connection to my server. I have tried using the ftp://username:[email protected]/ but to no avail. This is my code:

#include <stdio.h>
#include <string.h>
#include <curl/curl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <errno.h>
#ifdef WIN32
#include <io.h>
#else
#include <unistd.h>
#endif
#define LOCAL_FILE      "C:/myfile.txt"
#define UPLOAD_FILE_AS  "file.txt"
#define REMOTE_URL      "ftp://example.com/"  UPLOAD_FILE_AS
#define RENAME_FILE_TO  "file.txt"
static size_t read_callback(void *ptr, size_t size, size_t nmemb, void *stream)
{
    curl_off_t nread;
    size_t retcode = fread(ptr, size, nmemb, (FILE *) stream);
    nread = (curl_off_t) retcode;
    fprintf(stderr, "*** We read %" CURL_FORMAT_CURL_OFF_T " bytes from filen", nread);
    return retcode;
}

int main(void)
{
    CURL *curl;
    CURLcode res;
    FILE *hd_src;
    struct stat file_info;
    curl_off_t fsize;
    struct curl_slist *headerlist = NULL;
    static const char buf_1[] = "RNFR " UPLOAD_FILE_AS;
    static const char buf_2[] = "RNTO " RENAME_FILE_TO;

    if (stat(LOCAL_FILE, &file_info)) {
    printf("Couldnt open '%s': %sn", LOCAL_FILE, strerror(errno));
    return 1;
    }
    fsize = (curl_off_t) file_info.st_size;
    printf("Local file size: %" CURL_FORMAT_CURL_OFF_T " bytes.n", fsize);
    hd_src = fopen(LOCAL_FILE, "rb");
    curl_global_init(CURL_GLOBAL_ALL);
    curl = curl_easy_init();
    if (curl) {
    headerlist = curl_slist_append(headerlist, buf_1);
    headerlist = curl_slist_append(headerlist, buf_2);
    curl_easy_setopt(curl, CURLOPT_READFUNCTION, read_callback);
    curl_easy_setopt(curl, CURLOPT_UPLOAD, 1L);
    curl_easy_setopt(curl, CURLOPT_URL, REMOTE_URL);
    curl_easy_setopt(curl, CURLOPT_POSTQUOTE, headerlist);
    curl_easy_setopt(curl, CURLOPT_READDATA, hd_src);
    curl_easy_setopt(curl, CURLOPT_INFILESIZE_LARGE, (curl_off_t) fsize);

    res = curl_easy_perform(curl);

    curl_slist_free_all(headerlist);

    /* always cleanup */
    curl_easy_cleanup(curl);
    }
    fclose(hd_src);     /* close the local file */

    curl_global_cleanup();
    return 0;
}

Answer 1

You have to pass the required username and password to libcurl. This is done via the option CURLOPT_USERPWD, just set it as follows:

curl_easy_setopt( curl, CURLOPT_USERPWD, "username:password" );