source: TI05-delivery/trunk/src/python_ext/bbftpd.c @ 1144

/**
 * NDG python embedded bbftp daemon module.
 *
 * @author Stephen Pascoe
 *
 * Copyright (C) 2006 CCLRC & NERC
 *
 * This software may be distributed under the terms of the Q Public Licence, version 1.0 or later.
 *
 */

#include <Python.h>
#include <ndg.h>

extern char **environ;
/*
 * variables and prototypes from bbftpd source
 */

extern int be_daemon;
extern int newcontrolport;

int bbftpd_main(int argc, char **argv, char **envp);
int ndg_message_send(char *buffer, int buffertosendlength, char *logmessage) ;
int ndg_message_recv(char **buffer, int *length, char *logmessage) ;

/*
 * Static variables.
 */
static PyObject *authHandler = NULL;
static PyObject *authzHandler = NULL;

static void ndg_pyerr_to_logmessage(char *logmessage, char *prefix);

/*---------------------------------------------------------------------------------------------------
 * The following functions interact with bbftpd_private_user.  They are placed here to separate
 * python and bbftp APIs.
 *
 */

/**
 * Copy the python exception message to a bbftp logmessage.
 *
 * If the python error indicator is set it will be cleared.
 * If the python error indicator is not set the empty string will be copied to \a logmessage.
 * The exception message is truncated if it exceeds \c NDG_MAX_LOGMESSAGE.
 *
 * @param logmessage a pointer to a buffer of length \c NDG_MAX_LOGMESSAGE
 *     for storing an error message when returning -1.
 * @param prefix a string to be prefixed to the logmessage.
 */
static void ndg_pyerr_to_logmessage(char *logmessage, char *prefix) {
  PyObject *ptype, *pvalue, *ptraceback, *obj;
  char *exname, *exvalue;

  PyErr_Fetch(&ptype, &pvalue, &ptraceback);
  
  if ((obj = PyObject_GetAttrString(ptype, "__name__")) == NULL) goto error;
  exname = PyString_AsString(obj); Py_DECREF(obj);
  if (exname == NULL) goto error;

  if ((obj = PyObject_Str(pvalue)) == NULL) goto error;
  exvalue = PyString_AsString(obj); Py_DECREF(obj);
  if (exvalue == NULL) goto error;

  snprintf(logmessage, NDG_MAX_LOGMESSAGE, "%s: %s: %s", prefix, exname, exvalue);
  return;
  
 error:
  sprintf("ndg_pyerr_to_logmessage: internal python error", logmessage);
  return;
}

/**
 * Make a callback bbftpd->python to handle authentication.
 *
 * @param logmessage a pointer to a buffer of length \c NDG_MAX_LOGMESSAGE
 *     for storing an error message when returning -1.
 * @return 0 on success, -1 on failure
 */
int ndg_auth(char *logmessage) {

  if (authzHandler != NULL) {
    sprintf(logmessage, "ndg_auth: authzHandler already present");
    return -1;
  }
  
  if (authHandler == NULL) {
    sprintf(logmessage, "ndg_auth: no authHandler set");
    return -1;
  }

  /** @todo exceptions of type delivery.server.AuthenticationFailure should be logged as
   *      failure rather than error.
   */
  if ((authzHandler = PyObject_CallMethod(authHandler, "authorise", "")) == NULL) {
    ndg_pyerr_to_logmessage(logmessage, "ndg_auth");
    return -1;
  }

  /* Authorisation is considered failed if the return value isn't True.  */
  if (!PyObject_IsTrue(authzHandler)) {
    sprintf(logmessage, "ndg_auth: python authorisation failed");
    return -1;
  }

  return 0;
}

/**
 * retrieve the username from authzHandler.
 *
 * @param logmessage a pointer to a buffer of length \c NDG_MAX_LOGMESSAGE
 *     for storing an error message when returning NULL.
 * @return pointer to the username or NULL on failure
 */
char *ndg_getusername(char *logmessage) {
  char *username;
  PyObject *str_obj;

  if (authzHandler == NULL) {
    sprintf(logmessage, "bbftpd_private_auth_getusername: no authzHandler set");
    return NULL;
  }

  if ((str_obj = PyObject_GetAttrString(authzHandler, "username")) == NULL) {
    ndg_pyerr_to_logmessage(logmessage, "ndg_getusername");
    return NULL;
  }

  if ((username = PyString_AsString(str_obj)) == NULL) {
    ndg_pyerr_to_logmessage(logmessage, "ndg_getusername");
    Py_DECREF(str_obj);
    return NULL;
  }

  return username;
}


/**
 * Make a callback to do authorisation of a control command.
 *
 * @see bbftpd_private_authz_control()
 */
int ndg_authz_control(int msgcode, int transferoption, char *path, char *logmessage) {
  PyObject *ret_obj;

  if (authzHandler == NULL) {
    sprintf(logmessage, "ndg_authz_control: no authzHandler set");
    return -1;
  }
  
  if ((ret_obj = PyObject_CallMethod(authzHandler, "authzControl", "iis", msgcode, transferoption, path)) == NULL) {
    ndg_pyerr_to_logmessage(logmessage, "ndg_authz_control");
    return -1;
  }
  
  /* Authorisation fails if ret_obj is false. */
  if (!PyObject_IsTrue(ret_obj)) {
    ndg_pyerr_to_logmessage(logmessage, "ndg_authz_control");
    Py_DECREF(ret_obj);
    return -1;
  }

  return 0;
}

/**
 * Make a callback to do authorisation of a retr command.
 *
 * @see bbftpd_private_authz_retr()
 */
int ndg_authz_retr(char *path, char *logmessage) {
  PyObject *ret_obj;

  if (authzHandler == NULL) {
    sprintf(logmessage, "ndg_authz_retr: no authzHandler set");
    return -1;
  }
  
  if ((ret_obj = PyObject_CallMethod(authzHandler, "authzRetr", "s", path)) == NULL) {
    ndg_pyerr_to_logmessage(logmessage, "ndg_authz_retr");
    return -1;
  }
  
  /* Authorisation fails if ret_obj is false. */
  if (!PyObject_IsTrue(ret_obj)) {
    ndg_pyerr_to_logmessage(logmessage, "ndg_authz_retr");
    Py_DECREF(ret_obj);
    return -1;
  }

  return 0;
}


/**
 * Make a callback to do authorisation of a store command.
 *
 * @see bbftpd_private_authz_store()
 */
int ndg_authz_store(char *path, char *logmessage) {
  PyObject *ret_obj;

  if (authzHandler == NULL) {
    sprintf(logmessage, "ndg_authz_store: no authzHandler set");
    return -1;
  }
  
  if ((ret_obj = PyObject_CallMethod(authzHandler, "authzStore", "s", path)) == NULL) {
    ndg_pyerr_to_logmessage(logmessage, "ndg_authz_store");
    return -1;
  }
  
  /* Authorisation fails if ret_obj is false. */
  if (!PyObject_IsTrue(ret_obj)) {
    ndg_pyerr_to_logmessage(logmessage, "ndg_authz_store");
    Py_DECREF(ret_obj);
    return -1;
  }

  return 0;
}
 

     
/*-------------------------------------------------------------------------------------------------
 * Functions exported to python
 *
 */

/* send(string) */
static PyObject *bbftpd_send(PyObject *self, PyObject *args) {
  char *buffer, logmessage[1024];
  int len;

  if (!PyArg_ParseTuple(args, "s#", &buffer, &len)) {
    return NULL;
  }

  if (authHandler == NULL) {
    PyErr_SetString(PyExc_RuntimeError, "Must be called within a bbftpd callback");
    return NULL;
  }

  if (ndg_message_send(buffer, len, logmessage) == -1) {
    PyErr_SetString(PyExc_IOError, logmessage);
    return NULL;
  }

  Py_RETURN_NONE;
}

/* recv(length) -> string */
static PyObject *bbftpd_recv(PyObject *self, PyObject *args) {
  char *buffer, logmessage[1024];
  int len;
  PyObject *ret;

  if (!PyArg_ParseTuple(args, "")) {
    return NULL;
  }

  if (authHandler == NULL) {
    PyErr_SetString(PyExc_RuntimeError, "Must be called within a bbftpd callback");
    return NULL;
  }

  if (ndg_message_recv(&buffer, &len, logmessage) == -1) {
    PyErr_SetString(PyExc_IOError, logmessage);
    free(buffer);
    return NULL;
  }

  ret = Py_BuildValue("s#", buffer, len);
  free(buffer);
  return ret;
}



/**
 * Main entry point for the python module.
 */
static PyObject *bbftpd_run(PyObject *self, PyObject *args) {
  int argc, i;
  char **argv, **arg_p;
  int pid;
  char preargs[2][20] = { "bbftpd_embedded", "-b" };
  PyObject *daemon_args, *item;

  if (!PyArg_ParseTuple(args, "OO", &authHandler, &daemon_args)) {
    return NULL;
  }
  Py_INCREF(authHandler);
  Py_INCREF(daemon_args);

  /*
   * Convert arguments into a standard argv sequence.
   */
  argc = PySequence_Size(daemon_args);
  if ((argv = (char**)malloc((argc + 2)*sizeof(char*))) == NULL) {
    PyErr_SetString(PyExc_MemoryError, "malloc failed");
    Py_DECREF(daemon_args);
    return NULL;
  }

  // Add fixed arguments to daemon's argv
  arg_p = argv;
  *arg_p = preargs[0]; arg_p++;
  *arg_p = preargs[1]; arg_p++;

  for (i=0; i<argc; i++) {
    if ((item = PySequence_GetItem(daemon_args, i)) == NULL) {
      Py_DECREF(authHandler);
      Py_DECREF(daemon_args);
      return NULL;
    }
    if ((*arg_p = PyString_AsString(item)) == NULL) {
      free(argv);
      Py_DECREF(item);
      Py_DECREF(authHandler);
      Py_DECREF(daemon_args);
      return NULL;
    }
    arg_p++;
    Py_DECREF(item);
  }

  /*
   * We must reset some global variables so that bbftpd_run can be executed multiple times.
   */
  be_daemon = 0;

  pid = bbftpd_main(argc+2, argv, environ);

  free(argv);
  Py_DECREF(authHandler); authHandler = NULL;
  Py_DECREF(daemon_args);

  return Py_BuildValue("i", pid);
}

static PyMethodDef BbftpdMethods[] = {
  {
    "run", bbftpd_run, METH_VARARGS, 
    "Execute the bbftpd server.\n"
    "\n"
    "Forks an embedded bbftpd process as if it were executed\n"
    "with the command line $ bbftpd -b <args>."
    "\n"
    "@param args: command line arguments to pass to the server\n"
    "@return: the PID of the server process\n"
  },
  {
    "send", bbftpd_send, METH_VARARGS,
    "Send an authentication message to the client.\n"
    "\n"
    "Equivilent to bbftpd_private_send() C call.\n"
    "\n"
    "@param buffer: A string containing the message\n"
    "@raise IOError: if bbftpd_private_send() call fails\n"
  },
  {
    "recv", bbftpd_recv, METH_VARARGS,
    "Receive an authentication message from the client.\n"
    "\n"
    "Equivilent to bbftpd_private_recv() C call.\n"
    "\n"
    "@param len: The length of message to expect\n"
    "@return: A string containing the message\n"
    "@raise IOError: if bbftpd_private_recv() call fails\n"
  },
  {NULL, NULL, 0, NULL}
};

PyMODINIT_FUNC initbbftpd(void) {
  (void) Py_InitModule("bbftpd", BbftpdMethods);
}