sftpget: example showing a simple SFTP download

... using SSH-agent

docs/examples/.gitignore

@@ -34,6 +34,7 @@ resolve
 rtsp
 sendrecv
 sepheaders
+sftpget
 simple
 simplepost
 simplesmtp

docs/examples/Makefile.inc

@@ -5,7 +5,7 @@ check_PROGRAMS = 10-at-a-time anyauthput cookie_interface debug fileupload \
   persistant post-callback postit2 sepheaders simple simplepost simplessl  \
   sendrecv httpcustomheader certinfo chkspeed ftpgetinfo ftp-wildcard \
   smtp-multi simplesmtp smtp-tls rtsp externalsocket resolve \
-  progressfunc pop3s pop3slist imap url2file
+  progressfunc pop3s pop3slist imap url2file sftpget
 
 # These examples require external dependencies that may not be commonly
 # available on POSIX systems, so don't bother attempting to compile them here.

docs/examples/sftpget.c

+/***************************************************************************
+ *                                  _   _ ____  _
+ *  Project                     ___| | | |  _ \| |
+ *                             / __| | | | |_) | |
+ *                            | (__| |_| |  _ <| |___
+ *                             \___|\___/|_| \_\_____|
+ *
+ * Copyright (C) 1998 - 2012, 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 http://curl.haxx.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.
+ *
+ ***************************************************************************/
+
+#include <stdio.h>
+
+#include <curl/curl.h>
+
+/* define this to switch off the use of ssh-agent in this program */
+#undef DISABLE_SSH_AGENT
+
+/*
+ * This is an example showing how to get a single file from an SSH FTP server.
+ * It delays the actual destination file creation until the first write
+ * callback so that it won't create an empty file in case the remote file
+ * doesn't exist or something else fails.
+ */
+
+struct FtpFile {
+  const char *filename;
+  FILE *stream;
+};
+
+static size_t my_fwrite(void *buffer, size_t size, size_t nmemb,
+                        void *stream)
+{
+  struct FtpFile *out=(struct FtpFile *)stream;
+  if(out && !out->stream) {
+    /* open file for writing */
+    out->stream=fopen(out->filename, "wb");
+    if(!out->stream)
+      return -1; /* failure, can't open file to write */
+  }
+  return fwrite(buffer, size, nmemb, out->stream);
+}
+
+
+int main(void)
+{
+  CURL *curl;
+  CURLcode res;
+  struct FtpFile ftpfile={
+    "yourfile.bin", /* name to store the file as if succesful */
+    NULL
+  };
+
+  curl_global_init(CURL_GLOBAL_DEFAULT);
+
+  curl = curl_easy_init();
+  if(curl) {
+    /*
+     * You better replace the URL with one that works!
+     */
+    curl_easy_setopt(curl, CURLOPT_URL,
+                     "sftp://user@server/home/user/file.txt");
+    /* Define our callback to get called when there's data to be written */
+    curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, my_fwrite);
+    /* Set a pointer to our struct to pass to the callback */
+    curl_easy_setopt(curl, CURLOPT_WRITEDATA, &ftpfile);
+
+#ifndef DISABLE_SSH_AGENT
+    /* We activate ssh agent. For this to work you need
+       to have ssh-agent running (type set | grep SSH_AGENT to check) or
+       pageant on Windows (there is an icon in systray if so) */
+    curl_easy_setopt(curl, CURLOPT_SSH_AUTH_TYPES, CURLSSH_AUTH_AGENT);
+#endif
+
+    /* Switch on full protocol/debug output */
+    curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L);
+
+    res = curl_easy_perform(curl);
+
+    /* always cleanup */
+    curl_easy_cleanup(curl);
+
+    if(CURLE_OK != res) {
+      /* we failed */
+      fprintf(stderr, "curl told us %d\n", res);
+    }
+  }
+
+  if(ftpfile.stream)
+    fclose(ftpfile.stream); /* close the local file */
+
+  curl_global_cleanup();
+
+  return 0;
+}