ssh.c

          if(from >= size) {
            failf(data, "Offset (%"
                  FORMAT_OFF_T ") was beyond file size (%" FORMAT_OFF_T ")",
                  from, attrs.filesize);
            return CURLE_BAD_DOWNLOAD_RESUME;
          }
          if(from > to) {
            from = to;
            size = 0;
          }
          else {
            size = to - from + 1;
          }

          SFTP_SEEK(conn->proto.sshc.sftp_handle, from);
        }
        data->req.size = size;
        data->req.maxdownload = size;
        Curl_pgrsSetDownloadSize(data, size);
      }

      /* We can resume if we can seek to the resume position */
      if(data->state.resume_from) {
        if(data->state.resume_from < 0) {
          /* We're supposed to download the last abs(from) bytes */
          if((curl_off_t)attrs.filesize < -data->state.resume_from) {
            failf(data, "Offset (%"
                  FORMAT_OFF_T ") was beyond file size (%" FORMAT_OFF_T ")",
                  data->state.resume_from, attrs.filesize);
            return CURLE_BAD_DOWNLOAD_RESUME;
          }
          /* download from where? */
          data->state.resume_from += attrs.filesize;
        }
        else {
          if((curl_off_t)attrs.filesize < data->state.resume_from) {
            failf(data, "Offset (%" FORMAT_OFF_T
                  ") was beyond file size (%" FORMAT_OFF_T ")",
                  data->state.resume_from, attrs.filesize);
            return CURLE_BAD_DOWNLOAD_RESUME;
          }
        }
        /* Does a completed file need to be seeked and started or closed ? */
        /* Now store the number of bytes we are expected to download */
        data->req.size = attrs.filesize - data->state.resume_from;
        data->req.maxdownload = attrs.filesize - data->state.resume_from;
        Curl_pgrsSetDownloadSize(data,
                                 attrs.filesize - data->state.resume_from);
        SFTP_SEEK(sshc->sftp_handle, data->state.resume_from);
      }
    }
    /* Setup the actual download */
    if(data->req.size == 0) {
      /* no data to transfer */
      Curl_setup_transfer(conn, -1, -1, FALSE, NULL, -1, NULL);
      infof(data, "File already completely downloaded\n");
      state(conn, SSH_STOP);
      break;
    }
    else {
      Curl_setup_transfer(conn, FIRSTSOCKET, data->req.size,
                          FALSE, NULL, -1, NULL);

      /* not set by Curl_setup_transfer to preserve keepon bits */
      conn->writesockfd = conn->sockfd;

      /* we want to use the _receiving_ function even when the socket turns
         out writableable as the underlying libssh2 recv function will deal
         with both accordingly */
      conn->cselect_bits = CURL_CSELECT_IN;
    }
    if(result) {
      state(conn, SSH_SFTP_CLOSE);
      sshc->actualcode = result;
    }
    else {
      state(conn, SSH_STOP);
    }
    break;

    case SSH_SFTP_CLOSE:
      if(sshc->sftp_handle) {
        rc = libssh2_sftp_close(sshc->sftp_handle);
        if(rc == LIBSSH2_ERROR_EAGAIN) {
          break;
        }
        else if(rc < 0) {
          infof(data, "Failed to close libssh2 file\n");
        }
        sshc->sftp_handle = NULL;
      }
      if(sftp_scp) {
        Curl_safefree(sftp_scp->path);
        sftp_scp->path = NULL;
      }

      DEBUGF(infof(data, "SFTP DONE done\n"));

      /* Check if nextstate is set and move .nextstate could be POSTQUOTE_INIT
         After nextstate is executed,the control should come back to
         SSH_SFTP_CLOSE to pass the correct result back  */
      if(sshc->nextstate != SSH_NO_STATE) {
        state(conn, sshc->nextstate);
        sshc->nextstate = SSH_SFTP_CLOSE;
      }
      else {
        state(conn, SSH_STOP);
        result = sshc->actualcode;
      }
      break;

    case SSH_SFTP_SHUTDOWN:
      /* during times we get here due to a broken transfer and then the
         sftp_handle might not have been taken down so make sure that is done
         before we proceed */

      if(sshc->sftp_handle) {
        rc = libssh2_sftp_close(sshc->sftp_handle);
        if(rc == LIBSSH2_ERROR_EAGAIN) {
          break;
        }
        else if(rc < 0) {
          infof(data, "Failed to close libssh2 file\n");
        }
        sshc->sftp_handle = NULL;
      }
      if(sshc->sftp_session) {
        rc = libssh2_sftp_shutdown(sshc->sftp_session);
        if(rc == LIBSSH2_ERROR_EAGAIN) {
          break;
        }
        else if(rc < 0) {
          infof(data, "Failed to stop libssh2 sftp subsystem\n");
        }
        sshc->sftp_session = NULL;
      }

      Curl_safefree(sshc->homedir);
      sshc->homedir = NULL;
      conn->data->state.most_recent_ftp_entrypath = NULL;

      state(conn, SSH_SESSION_DISCONNECT);
      break;

    case SSH_SCP_TRANS_INIT:
      result = ssh_getworkingpath(conn, sshc->homedir, &sftp_scp->path);
      if(result) {
        sshc->actualcode = result;
        state(conn, SSH_STOP);
        break;
      }

      if(data->set.upload) {
        if(data->set.infilesize < 0) {
          failf(data, "SCP requires a known file size for upload");
          sshc->actualcode = CURLE_UPLOAD_FAILED;
          state(conn, SSH_SCP_CHANNEL_FREE);
          break;
        }
        state(conn, SSH_SCP_UPLOAD_INIT);
      }
      else {
        state(conn, SSH_SCP_DOWNLOAD_INIT);
      }
      break;

    case SSH_SCP_UPLOAD_INIT:
      /*
       * libssh2 requires that the destination path is a full path that
       * includes the destination file and name OR ends in a "/" .  If this is
       * not done the destination file will be named the same name as the last
       * directory in the path.
       */
      sshc->ssh_channel =
        SCP_SEND(sshc->ssh_session, sftp_scp->path, data->set.new_file_perms,
                 data->set.infilesize);
      if(!sshc->ssh_channel) {
        if(libssh2_session_last_errno(sshc->ssh_session) ==
           LIBSSH2_ERROR_EAGAIN) {
          rc = LIBSSH2_ERROR_EAGAIN;
          break;
        }
        else {
          int ssh_err;
          char *err_msg;

          ssh_err = (int)(libssh2_session_last_error(sshc->ssh_session,
                                                     &err_msg, NULL, 0));
          failf(conn->data, "%s", err_msg);
          state(conn, SSH_SCP_CHANNEL_FREE);
          sshc->actualcode = libssh2_session_error_to_CURLE(ssh_err);
          break;
        }
      }

      /* upload data */
      Curl_setup_transfer(conn, -1, data->req.size, FALSE, NULL,
                          FIRSTSOCKET, NULL);

      /* not set by Curl_setup_transfer to preserve keepon bits */
      conn->sockfd = conn->writesockfd;

      if(result) {
        state(conn, SSH_SCP_CHANNEL_FREE);
        sshc->actualcode = result;
      }
      else {
        /* we want to use the _sending_ function even when the socket turns
           out readable as the underlying libssh2 scp send function will deal
           with both accordingly */
        conn->cselect_bits = CURL_CSELECT_OUT;

        state(conn, SSH_STOP);
      }
      break;

    case SSH_SCP_DOWNLOAD_INIT:
    {
      /*
       * We must check the remote file; if it is a directory no values will
       * be set in sb
       */
      struct stat sb;
      curl_off_t bytecount;

      /* clear the struct scp recv will fill in */
      memset(&sb, 0, sizeof(struct stat));

      /* get a fresh new channel from the ssh layer */
      sshc->ssh_channel = libssh2_scp_recv(sshc->ssh_session,
                                           sftp_scp->path, &sb);
      if(!sshc->ssh_channel) {
        if(libssh2_session_last_errno(sshc->ssh_session) ==
           LIBSSH2_ERROR_EAGAIN) {
          rc = LIBSSH2_ERROR_EAGAIN;
          break;
        }
        else {
          int ssh_err;
          char *err_msg;

          ssh_err = (int)(libssh2_session_last_error(sshc->ssh_session,
                                                     &err_msg, NULL, 0));
          failf(conn->data, "%s", err_msg);
          state(conn, SSH_SCP_CHANNEL_FREE);
          sshc->actualcode = libssh2_session_error_to_CURLE(ssh_err);
          break;
        }
      }

      /* download data */
      bytecount = (curl_off_t)sb.st_size;
      data->req.maxdownload =  (curl_off_t)sb.st_size;
      Curl_setup_transfer(conn, FIRSTSOCKET, bytecount, FALSE, NULL, -1, NULL);

      /* not set by Curl_setup_transfer to preserve keepon bits */
      conn->writesockfd = conn->sockfd;

      /* we want to use the _receiving_ function even when the socket turns
         out writableable as the underlying libssh2 recv function will deal
         with both accordingly */
      conn->cselect_bits = CURL_CSELECT_IN;

      if(result) {
        state(conn, SSH_SCP_CHANNEL_FREE);
        sshc->actualcode = result;
      }
      else
        state(conn, SSH_STOP);
    }
    break;

    case SSH_SCP_DONE:
      if(data->set.upload)
        state(conn, SSH_SCP_SEND_EOF);
      else
        state(conn, SSH_SCP_CHANNEL_FREE);
      break;

    case SSH_SCP_SEND_EOF:
      if(sshc->ssh_channel) {
        rc = libssh2_channel_send_eof(sshc->ssh_channel);
        if(rc == LIBSSH2_ERROR_EAGAIN) {
          break;
        }
        else if(rc) {
          infof(data, "Failed to send libssh2 channel EOF\n");
        }
      }
      state(conn, SSH_SCP_WAIT_EOF);
      break;

    case SSH_SCP_WAIT_EOF:
      if(sshc->ssh_channel) {
        rc = libssh2_channel_wait_eof(sshc->ssh_channel);
        if(rc == LIBSSH2_ERROR_EAGAIN) {
          break;
        }
        else if(rc) {
          infof(data, "Failed to get channel EOF: %d\n", rc);
        }
      }
      state(conn, SSH_SCP_WAIT_CLOSE);
      break;

    case SSH_SCP_WAIT_CLOSE:
      if(sshc->ssh_channel) {
        rc = libssh2_channel_wait_closed(sshc->ssh_channel);
        if(rc == LIBSSH2_ERROR_EAGAIN) {
          break;
        }
        else if(rc) {
          infof(data, "Channel failed to close: %d\n", rc);
        }
      }
      state(conn, SSH_SCP_CHANNEL_FREE);
      break;

    case SSH_SCP_CHANNEL_FREE:
      if(sshc->ssh_channel) {
        rc = libssh2_channel_free(sshc->ssh_channel);
        if(rc == LIBSSH2_ERROR_EAGAIN) {
          break;
        }
        else if(rc < 0) {
          infof(data, "Failed to free libssh2 scp subsystem\n");
        }
        sshc->ssh_channel = NULL;
      }
      DEBUGF(infof(data, "SCP DONE phase complete\n"));
#if 0 /* PREV */
      state(conn, SSH_SESSION_DISCONNECT);
#endif
      state(conn, SSH_STOP);
      result = sshc->actualcode;
      break;

    case SSH_SESSION_DISCONNECT:
      /* during weird times when we've been prematurely aborted, the channel
         is still alive when we reach this state and we MUST kill the channel
         properly first */
      if(sshc->ssh_channel) {
        rc = libssh2_channel_free(sshc->ssh_channel);
        if(rc == LIBSSH2_ERROR_EAGAIN) {
          break;
        }
        else if(rc < 0) {
          infof(data, "Failed to free libssh2 scp subsystem\n");
        }
        sshc->ssh_channel = NULL;
      }

      if(sshc->ssh_session) {
        rc = libssh2_session_disconnect(sshc->ssh_session, "Shutdown");
        if(rc == LIBSSH2_ERROR_EAGAIN) {
          break;
        }
        else if(rc < 0) {
          infof(data, "Failed to disconnect libssh2 session\n");
        }
      }

      Curl_safefree(sshc->homedir);
      sshc->homedir = NULL;
      conn->data->state.most_recent_ftp_entrypath = NULL;

      state(conn, SSH_SESSION_FREE);
      break;

    case SSH_SESSION_FREE:
#ifdef HAVE_LIBSSH2_KNOWNHOST_API
      if(sshc->kh) {
        libssh2_knownhost_free(sshc->kh);
        sshc->kh = NULL;
      }
#endif

      if(sshc->ssh_session) {
        rc = libssh2_session_free(sshc->ssh_session);
        if(rc == LIBSSH2_ERROR_EAGAIN) {
          break;
        }
        else if(rc < 0) {
          infof(data, "Failed to free libssh2 session\n");
        }
        sshc->ssh_session = NULL;
      }
      conn->bits.close = TRUE;
      sshc->nextstate = SSH_NO_STATE;
      state(conn, SSH_STOP);
      result = sshc->actualcode;
      break;

    case SSH_QUIT:
      /* fallthrough, just stop! */
    default:
      /* internal error */
      sshc->nextstate = SSH_NO_STATE;
      state(conn, SSH_STOP);
      break;
    }

  } while(!rc && (sshc->state != SSH_STOP));

  if(rc == LIBSSH2_ERROR_EAGAIN) {
    /* we would block, we need to wait for the socket to be ready (in the
       right direction too)! */
    *block = TRUE;
  }

  return result;
}

/* called by the multi interface to figure out what socket(s) to wait for and
   for what actions in the DO_DONE, PERFORM and WAITPERFORM states */
static int ssh_perform_getsock(const struct connectdata *conn,
                               curl_socket_t *sock, /* points to numsocks
                                                       number of sockets */
                               int numsocks)
{
#ifdef HAVE_LIBSSH2_SESSION_BLOCK_DIRECTION
  int bitmap = GETSOCK_BLANK;
  (void)numsocks;

  sock[0] = conn->sock[FIRSTSOCKET];

  if(conn->waitfor & KEEP_RECV)
    bitmap |= GETSOCK_READSOCK(FIRSTSOCKET);

  if(conn->waitfor & KEEP_SEND)
    bitmap |= GETSOCK_WRITESOCK(FIRSTSOCKET);

  return bitmap;
#else
  /* if we don't know the direction we can use the generic *_getsock()
     function even for the protocol_connect and doing states */
  return Curl_single_getsock(conn, sock, numsocks);
#endif
}

/* Generic function called by the multi interface to figure out what socket(s)
   to wait for and for what actions during the DOING and PROTOCONNECT states*/
static int ssh_getsock(struct connectdata *conn,
                       curl_socket_t *sock, /* points to numsocks number
                                               of sockets */
                       int numsocks)
{
#ifndef HAVE_LIBSSH2_SESSION_BLOCK_DIRECTION
  (void)conn;
  (void)sock;
  (void)numsocks;
  /* if we don't know any direction we can just play along as we used to and
     not provide any sensible info */
  return GETSOCK_BLANK;
#else
  /* if we know the direction we can use the generic *_getsock() function even
     for the protocol_connect and doing states */
  return ssh_perform_getsock(conn, sock, numsocks);
#endif
}

#ifdef HAVE_LIBSSH2_SESSION_BLOCK_DIRECTION
/*
 * When one of the libssh2 functions has returned LIBSSH2_ERROR_EAGAIN this
 * function is used to figure out in what direction and stores this info so
 * that the multi interface can take advantage of it. Make sure to call this
 * function in all cases so that when it _doesn't_ return EAGAIN we can
 * restore the default wait bits.
 */
static void ssh_block2waitfor(struct connectdata *conn, bool block)
{
  struct ssh_conn *sshc = &conn->proto.sshc;
  int dir;
  if(!block)
    conn->waitfor = 0;
  else if((dir = libssh2_session_block_directions(sshc->ssh_session))) {
    /* translate the libssh2 define bits into our own bit defines */
    conn->waitfor = ((dir&LIBSSH2_SESSION_BLOCK_INBOUND)?KEEP_RECV:0) |
      ((dir&LIBSSH2_SESSION_BLOCK_OUTBOUND)?KEEP_SEND:0);
  }
  else
    /* It didn't block or libssh2 didn't reveal in which direction, put back
       the original set */
    conn->waitfor = sshc->orig_waitfor;
}
#else
  /* no libssh2 directional support so we simply don't know */
#define ssh_block2waitfor(x,y)
#endif

/* called repeatedly until done from multi.c */
static CURLcode ssh_multi_statemach(struct connectdata *conn, bool *done)
{
  struct ssh_conn *sshc = &conn->proto.sshc;
  CURLcode result = CURLE_OK;
  bool block; /* we store the status and use that to provide a ssh_getsock()
                 implementation */

  result = ssh_statemach_act(conn, &block);
  *done = (bool)(sshc->state == SSH_STOP);
  ssh_block2waitfor(conn, block);

  return result;
}

static CURLcode ssh_easy_statemach(struct connectdata *conn,
                                   bool duringconnect)
{
  struct ssh_conn *sshc = &conn->proto.sshc;
  CURLcode result = CURLE_OK;
  struct SessionHandle *data = conn->data;

  while((sshc->state != SSH_STOP) && !result) {
    bool block;
    long left;

    result = ssh_statemach_act(conn, &block);
    if(result)
      break;

    if(Curl_pgrsUpdate(conn))
      return CURLE_ABORTED_BY_CALLBACK;
    else {
      struct timeval now = Curl_tvnow();
      result = Curl_speedcheck(data, now);
      if(result)
        break;
    }

    left = Curl_timeleft(data, NULL, duringconnect);
    if(left < 0) {
      failf(data, "Operation timed out\n");
      return CURLE_OPERATION_TIMEDOUT;
    }

#ifdef HAVE_LIBSSH2_SESSION_BLOCK_DIRECTION
    if((CURLE_OK == result) && block) {
      int dir = libssh2_session_block_directions(sshc->ssh_session);
      curl_socket_t sock = conn->sock[FIRSTSOCKET];
      curl_socket_t fd_read = CURL_SOCKET_BAD;
      curl_socket_t fd_write = CURL_SOCKET_BAD;
      if(LIBSSH2_SESSION_BLOCK_INBOUND & dir)
        fd_read = sock;
      if(LIBSSH2_SESSION_BLOCK_OUTBOUND & dir)
        fd_write = sock;
      /* wait for the socket to become ready */
      Curl_socket_ready(fd_read, fd_write,
                        (int)(left>1000?1000:left)); /* ignore result */
    }
#endif

  }

  return result;
}

/*
 * SSH setup and connection
 */
static CURLcode ssh_init(struct connectdata *conn)
{
  struct SessionHandle *data = conn->data;
  struct SSHPROTO *ssh;
  struct ssh_conn *sshc = &conn->proto.sshc;

  sshc->actualcode = CURLE_OK; /* reset error code */
  sshc->secondCreateDirs =0;   /* reset the create dir attempt state
                                  variable */

  if(data->state.proto.ssh)
    return CURLE_OK;

  ssh = calloc(1, sizeof(struct SSHPROTO));
  if(!ssh)
    return CURLE_OUT_OF_MEMORY;

  data->state.proto.ssh = ssh;

  return CURLE_OK;
}

static Curl_recv scp_recv, sftp_recv;
static Curl_send scp_send, sftp_send;

/*
 * Curl_ssh_connect() gets called from Curl_protocol_connect() to allow us to
 * do protocol-specific actions at connect-time.
 */
static CURLcode ssh_connect(struct connectdata *conn, bool *done)
{
#ifdef CURL_LIBSSH2_DEBUG
  curl_socket_t sock;
#endif
  struct ssh_conn *ssh;
  CURLcode result;
  struct SessionHandle *data = conn->data;

  /* We default to persistent connections. We set this already in this connect
     function to make the re-use checks properly be able to check this bit. */
  conn->bits.close = FALSE;

  /* If there already is a protocol-specific struct allocated for this
     sessionhandle, deal with it */
  Curl_reset_reqproto(conn);

  result = ssh_init(conn);
  if(result)
    return result;

  if(conn->handler->protocol & CURLPROTO_SCP) {
    conn->recv[FIRSTSOCKET] = scp_recv;
    conn->send[FIRSTSOCKET] = scp_send;
  }
  else {
    conn->recv[FIRSTSOCKET] = sftp_recv;
    conn->send[FIRSTSOCKET] = sftp_send;
  }
  ssh = &conn->proto.sshc;

#ifdef CURL_LIBSSH2_DEBUG
  if(conn->user) {
    infof(data, "User: %s\n", conn->user);
  }
  if(conn->passwd) {
    infof(data, "Password: %s\n", conn->passwd);
  }
  sock = conn->sock[FIRSTSOCKET];
#endif /* CURL_LIBSSH2_DEBUG */

  ssh->ssh_session = libssh2_session_init_ex(my_libssh2_malloc,
                                             my_libssh2_free,
                                             my_libssh2_realloc, conn);
  if(ssh->ssh_session == NULL) {
    failf(data, "Failure initialising ssh session");
    return CURLE_FAILED_INIT;
  }

#ifdef HAVE_LIBSSH2_KNOWNHOST_API
  if(data->set.str[STRING_SSH_KNOWNHOSTS]) {
    int rc;
    ssh->kh = libssh2_knownhost_init(ssh->ssh_session);
    if(!ssh->kh) {
      /* eeek. TODO: free the ssh_session! */
      return CURLE_FAILED_INIT;
    }

    /* read all known hosts from there */
    rc = libssh2_knownhost_readfile(ssh->kh,
                                    data->set.str[STRING_SSH_KNOWNHOSTS],
                                    LIBSSH2_KNOWNHOST_FILE_OPENSSH);
    if(rc < 0)
      infof(data, "Failed to read known hosts from %s\n",
            data->set.str[STRING_SSH_KNOWNHOSTS]);
  }
#endif /* HAVE_LIBSSH2_KNOWNHOST_API */

#ifdef CURL_LIBSSH2_DEBUG
  libssh2_trace(ssh->ssh_session, ~0);
  infof(data, "SSH socket: %d\n", (int)sock);
#endif /* CURL_LIBSSH2_DEBUG */

  state(conn, SSH_INIT);

  if(data->state.used_interface == Curl_if_multi)
    result = ssh_multi_statemach(conn, done);
  else {
    result = ssh_easy_statemach(conn, TRUE);
    if(!result)
      *done = TRUE;
  }

  return result;
}

/*
 ***********************************************************************
 *
 * scp_perform()
 *
 * This is the actual DO function for SCP. Get a file according to
 * the options previously setup.
 */

static
CURLcode scp_perform(struct connectdata *conn,
                      bool *connected,
                      bool *dophase_done)
{
  CURLcode result = CURLE_OK;

  DEBUGF(infof(conn->data, "DO phase starts\n"));

  *dophase_done = FALSE; /* not done yet */

  /* start the first command in the DO phase */
  state(conn, SSH_SCP_TRANS_INIT);

  /* run the state-machine */
  if(conn->data->state.used_interface == Curl_if_multi) {
    result = ssh_multi_statemach(conn, dophase_done);
  }
  else {
    result = ssh_easy_statemach(conn, FALSE);
    *dophase_done = TRUE; /* with the easy interface we are done here */
  }
  *connected = conn->bits.tcpconnect;

  if(*dophase_done) {
    DEBUGF(infof(conn->data, "DO phase is complete\n"));
  }

  return result;
}

/* called from multi.c while DOing */
static CURLcode scp_doing(struct connectdata *conn,
                               bool *dophase_done)
{
  CURLcode result;
  result = ssh_multi_statemach(conn, dophase_done);

  if(*dophase_done) {
    DEBUGF(infof(conn->data, "DO phase is complete\n"));
  }
  return result;
}

/*
 * The DO function is generic for both protocols. There was previously two
 * separate ones but this way means less duplicated code.
 */

static CURLcode ssh_do(struct connectdata *conn, bool *done)
{
  CURLcode res;
  bool connected = 0;
  struct SessionHandle *data = conn->data;

  *done = FALSE; /* default to false */

  /*
    Since connections can be re-used between SessionHandles, this might be a
    connection already existing but on a fresh SessionHandle struct so we must
    make sure we have a good 'struct SSHPROTO' to play with. For new
    connections, the struct SSHPROTO is allocated and setup in the
    ssh_connect() function.
  */
  Curl_reset_reqproto(conn);
  res = ssh_init(conn);
  if(res)
    return res;

  data->req.size = -1; /* make sure this is unknown at this point */

  Curl_pgrsSetUploadCounter(data, 0);
  Curl_pgrsSetDownloadCounter(data, 0);
  Curl_pgrsSetUploadSize(data, 0);
  Curl_pgrsSetDownloadSize(data, 0);

  if(conn->handler->protocol & CURLPROTO_SCP)
    res = scp_perform(conn, &connected,  done);
  else
    res = sftp_perform(conn, &connected,  done);

  return res;
}

/* BLOCKING, but the function is using the state machine so the only reason
   this is still blocking is that the multi interface code has no support for
   disconnecting operations that takes a while */
static CURLcode scp_disconnect(struct connectdata *conn, bool dead_connection)
{
  CURLcode result = CURLE_OK;
  struct ssh_conn *ssh = &conn->proto.sshc;
  (void) dead_connection;

  Curl_safefree(conn->data->state.proto.ssh);
  conn->data->state.proto.ssh = NULL;

  if(ssh->ssh_session) {
    /* only if there's a session still around to use! */

    state(conn, SSH_SESSION_DISCONNECT);

    result = ssh_easy_statemach(conn, FALSE);
  }

  return result;
}

/* generic done function for both SCP and SFTP called from their specific
   done functions */
static CURLcode ssh_done(struct connectdata *conn, CURLcode status)
{
  CURLcode result = CURLE_OK;
  struct SSHPROTO *sftp_scp = conn->data->state.proto.ssh;

  if(status == CURLE_OK) {
    /* run the state-machine

       TODO: when the multi interface is used, this _really_ should be using
       the ssh_multi_statemach function but we have no general support for
       non-blocking DONE operations, not in the multi state machine and with
       Curl_done() invokes on several places in the code!
    */
    result = ssh_easy_statemach(conn, FALSE);
  }
  else
    result = status;

  if(sftp_scp) {
    Curl_safefree(sftp_scp->path);
    sftp_scp->path = NULL;
  }
  Curl_pgrsDone(conn);

  conn->data->req.keepon = 0; /* clear all bits */
  return result;
}


static CURLcode scp_done(struct connectdata *conn, CURLcode status,
                         bool premature)
{
  (void)premature; /* not used */

  if(status == CURLE_OK)
    state(conn, SSH_SCP_DONE);

  return ssh_done(conn, status);

}

/* return number of received (decrypted) bytes */
static ssize_t scp_send(struct connectdata *conn, int sockindex,
                        const void *mem, size_t len, CURLcode *err)
{
  ssize_t nwrite;
  (void)sockindex; /* we only support SCP on the fixed known primary socket */

  /* libssh2_channel_write() returns int! */
  nwrite = (ssize_t)
    libssh2_channel_write(conn->proto.sshc.ssh_channel, mem, len);

  ssh_block2waitfor(conn, (nwrite == LIBSSH2_ERROR_EAGAIN)?TRUE:FALSE);

  if(nwrite == LIBSSH2_ERROR_EAGAIN) {
    *err = CURLE_AGAIN;
    nwrite = 0;
  }

  return nwrite;
}

/*
 * If the read would block (EWOULDBLOCK) we return -1. Otherwise we return
 * a regular CURLcode value.
 */
static ssize_t scp_recv(struct connectdata *conn, int sockindex,
                        char *mem, size_t len, CURLcode *err)
{
  ssize_t nread;
  (void)sockindex; /* we only support SCP on the fixed known primary socket */

  /* libssh2_channel_read() returns int */
  nread = (ssize_t)
    libssh2_channel_read(conn->proto.sshc.ssh_channel, mem, len);

  ssh_block2waitfor(conn, (nread == LIBSSH2_ERROR_EAGAIN)?TRUE:FALSE);
  if(nread == LIBSSH2_ERROR_EAGAIN) {
    *err = CURLE_AGAIN;
    nread = -1;
  }

  return nread;
}

/*
 * =============== SFTP ===============
 */

/*
 ***********************************************************************
 *
 * sftp_perform()
 *
 * This is the actual DO function for SFTP. Get a file/directory according to
 * the options previously setup.
 */

static
CURLcode sftp_perform(struct connectdata *conn,
                      bool *connected,
                      bool *dophase_done)
{
  CURLcode result = CURLE_OK;

  DEBUGF(infof(conn->data, "DO phase starts\n"));

  *dophase_done = FALSE; /* not done yet */

  /* start the first command in the DO phase */
  state(conn, SSH_SFTP_QUOTE_INIT);

  /* run the state-machine */
  if(conn->data->state.used_interface == Curl_if_multi) {
    result = ssh_multi_statemach(conn, dophase_done);
  }
  else {
    result = ssh_easy_statemach(conn, FALSE);
    *dophase_done = TRUE; /* with the easy interface we are done here */
  }
  *connected = conn->bits.tcpconnect;

  if(*dophase_done) {
    DEBUGF(infof(conn->data, "DO phase is complete\n"));
  }

  return result;
}

/* called from multi.c while DOing */
static CURLcode sftp_doing(struct connectdata *conn,
                           bool *dophase_done)
{
  CURLcode result;
  result = ssh_multi_statemach(conn, dophase_done);

  if(*dophase_done) {
    DEBUGF(infof(conn->data, "DO phase is complete\n"));
  }
  return result;
}

/* BLOCKING, but the function is using the state machine so the only reason
   this is still blocking is that the multi interface code has no support for
   disconnecting operations that takes a while */
static CURLcode sftp_disconnect(struct connectdata *conn, bool dead_connection)
{
  CURLcode result = CURLE_OK;
  (void) dead_connection;

  DEBUGF(infof(conn->data, "SSH DISCONNECT starts now\n"));

  Curl_safefree(conn->data->state.proto.ssh);
  conn->data->state.proto.ssh = NULL;

  if(conn->proto.sshc.ssh_session) {
    /* only if there's a session still around to use! */
    state(conn, SSH_SFTP_SHUTDOWN);
    result = ssh_easy_statemach(conn, FALSE);
  }

  DEBUGF(infof(conn->data, "SSH DISCONNECT is done\n"));

  return result;

}

static CURLcode sftp_done(struct connectdata *conn, CURLcode status,
                               bool premature)
{
  struct ssh_conn *sshc = &conn->proto.sshc;

  if(status == CURLE_OK) {
    /* Post quote commands are executed after the SFTP_CLOSE state to avoid
       errors that could happen due to open file handles during POSTQUOTE
       operation */
    if(!status && !premature && conn->data->set.postquote) {
      sshc->nextstate = SSH_SFTP_POSTQUOTE_INIT;
      state(conn, SSH_SFTP_CLOSE);
    }
    else
      state(conn, SSH_SFTP_CLOSE);
  }
  return ssh_done(conn, status);
}

/* return number of sent bytes */
static ssize_t sftp_send(struct connectdata *conn, int sockindex,
                         const void *mem, size_t len, CURLcode *err)
{
  ssize_t nwrite;   /* libssh2_sftp_write() used to return size_t in 0.14
                       but is changed to ssize_t in 0.15. These days we don't
                       support libssh2 0.15*/
  (void)sockindex;

  nwrite = libssh2_sftp_write(conn->proto.sshc.sftp_handle, mem, len);

  ssh_block2waitfor(conn, (nwrite == LIBSSH2_ERROR_EAGAIN)?TRUE:FALSE);

  if(nwrite == LIBSSH2_ERROR_EAGAIN) {
    *err = CURLE_AGAIN;
    nwrite = 0;
  }

  return nwrite;
}

/*