[libcurl] ftp 업로드 (put)

임베디드 리눅스 제품 군도 FTP서버에서 파일을 다운로드하거나 업로드 해야 하는 일이 있다.

(아직도 프로그램 업데이트를 위해 랜포트 검사 겸 TFTP를 많이 사용한다)

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같은 네트워크는 아니고, 원격으로 파일을 주고 받기 위해 FTP를 사용해야 하는데

여기서 libcurl을 이용하는 것이 개발시간을 많이 단축할수있다. 또 HTTP 프로토콜도 간단하게 구현할수있어서 좋다.​

 

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Curl을 개발PC에 설치한다. 설치방법은 링크를 참조한다. 우분투에서 cURL(libcurl) 설치 및 사용 :: 게으른 엔지니어

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만약 임베디드 리눅스 이라면, 직접 소스를 다운받아서 빌드하거나 buildroot 작업시 기본 라이브러리에 포함하기를 추천한다.

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테스트할 소스코드는 libcurl - source code examples 에 가서 가져온다. ftpget과 gtpupload 파일이다. 그외의 다양한 예제파일이 있으니 나중을 위해 북마크를 추천한다. 빌드는 -lcurl만 추가하고 빌드하면 된다.

빌드화면

실행화면

업로드 된 파일

예제 ftpupload.c 에서 바꾼 것은 FTP Url 변경, FTP 포트를 대상포트번호에 맞변경 (2222), 접속할 ID와 Passwd의 설정이다. Curl은 설정 -> 실행만 하면 기본적인 동작을 알아서 해주기 때문에 초기 설정만 잘해놓으면 따로 처리할것이 없다.
아래 소스는 URL만 넣고 테스트하면 정상 실행되는 코드이다.

/***************************************************************************
 *                                  _   _ ____  _
 *  Project                     ___| | | |  _ \| |
 *                             / __| | | | |_) | |
 *                            | (__| |_| |  _ <| |___
 *                             \___|\___/|_| \_\_____|
 *
 * Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
 *
 * This software is licensed as described in the file COPYING, which
 * you should have received as part of this distribution. The terms
 * are also available at https://curl.se/docs/copyright.html.
 *
 * You may opt to use, copy, modify, merge, publish, distribute and/or sell
 * copies of the Software, and permit persons to whom the Software is
 * furnished to do so, under the terms of the COPYING file.
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
 * KIND, either express or implied.
 *
 * SPDX-License-Identifier: curl
 *
 ***************************************************************************/
#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
 
/* <DESC>
 * Performs an FTP upload and renames the file just after a successful
 * transfer.
 * </DESC>
 */
 
#define LOCAL_FILE      "ftp.c"
#define UPLOAD_FILE_AS  "while-uploading.c"
#define REMOTE_URL      "ftp://*******.ipdisk.co.kr/HDD1/work/"  UPLOAD_FILE_AS
//URL은 환경에 맞춰 재설정바랍니다.
#define RENAME_FILE_TO  "renamed-and-fine.c"
 
/* NOTE: if you want this example to work on Windows with libcurl as a
   DLL, you MUST also provide a read callback with CURLOPT_READFUNCTION.
   Failing to do so will give you a crash since a DLL may not use the
   variable's memory when passed in to it from an app like this. */
static size_t read_callback(char *ptr, size_t size, size_t nmemb, void *stream)
{
  unsigned long nread;
  /* in real-world cases, this would probably get this data differently
     as this fread() stuff is exactly what the library already would do
     by default internally */
  size_t retcode = fread(ptr, size, nmemb, stream);
 
  if(retcode > 0) {
    nread = (unsigned long)retcode;
    fprintf(stderr, "*** We read %lu bytes from file\n", nread);
  }
 
  return retcode;
}
 
int main(void)
{
  CURL *curl;
  CURLcode res;
  FILE *hd_src;
  struct stat file_info;
  unsigned long fsize;
 
  struct curl_slist *headerlist = NULL;
  static const char buf_1 [] = "RNFR " UPLOAD_FILE_AS;
  static const char buf_2 [] = "RNTO " RENAME_FILE_TO;
 
  /* get the file size of the local file */
  if(stat(LOCAL_FILE, &file_info)) {
    printf("Couldn't open '%s': %s\n", LOCAL_FILE, strerror(errno));
    return 1;
  }
  fsize = (unsigned long)file_info.st_size;
 
  printf("Local file size: %lu bytes.\n", fsize);
 
  /* get a FILE * of the same file */
  hd_src = fopen(LOCAL_FILE, "rb");
 
  /* In windows, this will init the winsock stuff */
  curl_global_init(CURL_GLOBAL_ALL);
 
  /* get a curl handle */
  curl = curl_easy_init();
  if(curl) {
    /* build a list of commands to pass to libcurl */
    headerlist = curl_slist_append(headerlist, buf_1);
    headerlist = curl_slist_append(headerlist, buf_2);
 
    /* we want to use our own read function */
    curl_easy_setopt(curl, CURLOPT_READFUNCTION, read_callback);
 
    /* enable uploading */
    curl_easy_setopt(curl, CURLOPT_UPLOAD, 1L);
 
    /* specify target */
    curl_easy_setopt(curl, CURLOPT_URL, REMOTE_URL);
	//ftp remote port 설정  
	curl_easy_setopt(curl, CURLOPT_PORT, 2222);
	//접속 계정 설정 id:passwd
	curl_easy_setopt( curl, CURLOPT_USERPWD, "test:1234" );                
 
    /* pass in that last of FTP commands to run after the transfer */
    curl_easy_setopt(curl, CURLOPT_POSTQUOTE, headerlist);
 
    /* now specify which file to upload */
    curl_easy_setopt(curl, CURLOPT_READDATA, hd_src);
 
    /* Set the size of the file to upload (optional).  If you give a *_LARGE
       option you MUST make sure that the type of the passed-in argument is a
       curl_off_t. If you use CURLOPT_INFILESIZE (without _LARGE) you must
       make sure that to pass in a type 'long' argument. */
    curl_easy_setopt(curl, CURLOPT_INFILESIZE_LARGE,
                     (curl_off_t)fsize);
 
    /* Now run off and do what you have been told! */
    res = curl_easy_perform(curl);
    /* Check for errors */
    if(res != CURLE_OK)
      fprintf(stderr, "curl_easy_perform() failed: %s\n",
              curl_easy_strerror(res));
 
    /* clean up the FTP commands list */
    curl_slist_free_all(headerlist);
 
    /* always cleanup */
    curl_easy_cleanup(curl);
  }
  fclose(hd_src); /* close the local file */
 
  curl_global_cleanup();
  return 0;
}