Question

EDIT

I had a problem a while ago writing a program in C which utilizes scp to transfer and download files to a server. The program had to be written for windows. Initially I attempted to use the libCurl library which then I encountered different problems and it didn’t work well. After switching to libssh and the issue was fixed.


I’m posting a segment of my sample code which downloads a file from a remote server. hopefully this could be helpful to anyone who lands here.

int scp_recv_file(ssh_session in_session,
                 char * in_remotefile, char * in_localfile)
{
  ssh_scp   t_scp = NULL;
  int       t_rc, t_filesize, t_filemode = -1;
  char      *t_filename, *t_buffer;

  t_scp = ssh_scp_new
    (in_session, SSH_SCP_READ | SSH_SCP_RECURSIVE, in_remotefile);


  if (t_scp == NULL)
  {
    fprintf(stderr, "Error allocating scp session: %s\n",
            ssh_get_error(in_session));
    return SSH_ERROR;
  }

  t_rc = ssh_scp_init(t_scp);
  if (t_rc != SSH_OK)
  {
    fprintf(stderr, "Error initializing scp session: %s\n",
            ssh_get_error(in_session));
    ssh_scp_free(t_scp);
    return t_rc;
  }

  //create ssh pull a file request
  t_rc = ssh_scp_pull_request(t_scp);
  if (t_rc != SSH_SCP_REQUEST_NEWFILE)
  {
    fprintf(stderr, "Error receiving information about file: %s\n",
            ssh_get_error(in_session));
    return SSH_ERROR;
  }

  t_filesize = ssh_scp_request_get_size(t_scp);
  t_filename = strdup(ssh_scp_request_get_filename(t_scp));
  t_filemode = ssh_scp_request_get_permissions(t_scp);

  printf("Receiving file %s, size %d, permisssions 0%o\n",
          t_filename, t_filesize, t_filemode);

  t_buffer = malloc(t_filesize);
  if (t_buffer == NULL)
  {
    fprintf(stderr, "Memory allocation error\n");
    return SSH_ERROR;
  }

  ssh_scp_accept_request(t_scp);
  t_rc = ssh_scp_read(t_scp, t_buffer, t_filesize);
  if (t_rc == SSH_ERROR)
  {
    fprintf(stderr, "Error receiving file data: %s\n",
            ssh_get_error(in_session));
    free(t_buffer);
    return t_rc;
  }
  printf("Done\n");

  //write buffer to file
  writeToFile(in_localfile, t_buffer, t_filesize);
  //write(1, buffer, size);

  //free allocated memory
  free(t_buffer);
  free(t_filename);


  t_rc = ssh_scp_pull_request(t_scp);
  if (t_rc != SSH_SCP_REQUEST_EOF)
  {
    fprintf(stderr, "Unexpected request: %s\n",
            ssh_get_error(in_session));
    return SSH_ERROR;
  }



  //close scp and free
  ssh_scp_close(t_scp);
  ssh_scp_free(t_scp);
  return SSH_OK;
}

Answer 1

Switched to lilbssh. You can manage the scp stages manually and works ok. However, I don’t know if libssh2 is better or not. Any comments?