/*

 *   This program is free software; you can redistribute it and/or modify

 *   it under the terms of the GNU General Public License as published by

 *   the Free Software Foundation; either version 2 of the License, or

 *   (at your option) any later version.

 *

 *   This program is distributed in the hope that it will be useful,

 *   but WITHOUT ANY WARRANTY; without even the implied warranty of

 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 *   GNU General Public License for more details.

 *

 *   You should have received a copy of the GNU General Public License

 *   along with this program; if not, write to the Free Software

 *   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA

 */

/**

 * $Id: 1f915a094e973050483243aa965c5c6458d8a7d3 $

 *

 * @file unlang/function.c

 * @brief Unlang "function" keyword evaluation.

 * @copyright 2018,2021 The FreeRADIUS server project

 * @copyright 2018,2021 Arran Cudbard-Bell (a.cudbardb@freeradius.org)

 */

RCSID("$Id: 1f915a094e973050483243aa965c5c6458d8a7d3 $")

#include "action.h"

#include "unlang_priv.h"

#include "function.h"

#define FUNC(_state) *((void **)&(_state)->func)

#define REPEAT(_state) *((void **)&(_state)->repeat)

/*

 *  Some functions differ mainly in their parsing

 */

typedef struct {

  union {

    unlang_function_no_result_t nres;   //!< To call when going down the stack.

    unlang_function_with_result_t wres;   //!< To call when going down the stack.

  } func;

  char const      *func_name;   //!< Debug name for the function.

  union {

    unlang_function_no_result_t nres;   //!< To call when going back up the stack.

    unlang_function_with_result_t wres;   //!< To call when going back up the stack.

  } repeat;

  unlang_function_type_t    type;     //!< Record whether we need to call the

  char const      *repeat_name;   //!< Debug name for the repeat function.

  unlang_function_signal_t  signal;     //!< Signal function to call.

  fr_signal_t     sigmask;    //!< Signals to block.

  char const      *signal_name;   //!< Debug name for the signal function.

  void        *uctx;      //!< Uctx to pass to function.

} unlang_frame_state_func_t;

/** Static instruction for allowing modules/xlats to call functions within themselves, or submodules

 *

 */

static unlang_t function_instruction = {

  .type = UNLANG_TYPE_FUNCTION,

  .name = "function",

  .debug_name = "function",

  .actions = DEFAULT_MOD_ACTIONS,

};

/** Generic signal handler

 *

 * @param[in] request   being signalled.

 * @param[in] frame   being signalled.

 * @param[in] action    Type of signal.

 */

static void unlang_function_signal(request_t *request,

           unlang_stack_frame_t *frame, fr_signal_t action)

{

  unlang_frame_state_func_t *state = talloc_get_type_abort(frame->state, unlang_frame_state_func_t);

  if (!state->signal || (action & state->sigmask)) return;

  state->signal(request, action, state->uctx);

}

/*

 *  Don't let the callback mess with the current

 *  module permanently.

 */

#define STORE_CALLER \

  char const *caller; \

  caller = request->module; \

  request->module = NULL

#define RESTORE_CALLER \

  request->module = caller

/** Call a generic function that produces a result

 *

 * @param[out] p_result   The frame result.

 * @param[in] request   The current request.

 * @param[in] frame   The current frame.

 */

static unlang_action_t call_with_result_repeat(unlang_result_t *p_result, request_t *request, unlang_stack_frame_t *frame)

{

  unlang_action_t     ua;

  unlang_frame_state_func_t *state = talloc_get_type_abort(frame->state, unlang_frame_state_func_t);

  unlang_function_with_result_t func;

  STORE_CALLER;

  if (!REPEAT(state)) {

    RDEBUG4("Repeat function is NULL, likely due to previous yield, skipping call");

    ua = UNLANG_ACTION_CALCULATE_RESULT;

    goto done;

  }

  RDEBUG4("Calling repeat function %p (%s)", REPEAT(state), state->repeat_name);

  /*

   *  Only called once...

   */

  func = state->repeat.wres;

  REPEAT(state) = NULL;

  state->repeat_name = NULL;

  ua = func(p_result, request, state->uctx);

  if (REPEAT(state)) { /* set again by func */

    switch (ua) {

    case UNLANG_ACTION_CALCULATE_RESULT:

      break;

    default:

      frame_repeat(frame, call_with_result_repeat);

    }

  }

done:

  RESTORE_CALLER;

  return ua;

}

/** Call a generic function that produces a result

 *

 * @param[out] p_result   The frame result.

 * @param[in] request   The current request.

 * @param[in] frame   The current frame.

 */

static unlang_action_t call_with_result(unlang_result_t *p_result, request_t *request, unlang_stack_frame_t *frame)

{

  unlang_action_t     ua;

  unlang_frame_state_func_t *state = talloc_get_type_abort(frame->state, unlang_frame_state_func_t);

  STORE_CALLER;

  RDEBUG4("Calling function %p (%s)", FUNC(state), state->func_name);

  ua = state->func.wres(p_result, request, state->uctx);

  FUNC(state) = NULL;

  state->func_name = NULL;

  if (REPEAT(state)) {

    switch (ua) {

    case UNLANG_ACTION_CALCULATE_RESULT:

      break;

    default:

      frame_repeat(frame, call_with_result_repeat);

    }

  }

  RESTORE_CALLER;

  return ua;

}

/** Call a generic function that produces a result

 *

 * @param[out] p_result   The frame result.

 * @param[in] request   The current request.

 * @param[in] frame   The current frame.

 */

static unlang_action_t call_no_result_repeat(UNUSED unlang_result_t *p_result, request_t *request, unlang_stack_frame_t *frame)

{

  unlang_action_t     ua;

  unlang_frame_state_func_t *state = talloc_get_type_abort(frame->state, unlang_frame_state_func_t);

  unlang_function_no_result_t func;

  STORE_CALLER;

  if (!REPEAT(state)) {

    RDEBUG4("Repeat function is NULL, likely due to previous yield, skipping call");

    ua = UNLANG_ACTION_CALCULATE_RESULT;

    goto done;

  }

  RDEBUG4("Calling repeat function %p (%s)", REPEAT(state), state->repeat_name);

  /*

   *  Only called once...

   */

  func = state->repeat.nres;

  REPEAT(state) = NULL;

  state->repeat_name = NULL;

  ua = func(request, state->uctx);

  if (REPEAT(state)) { /* set again by func */

    switch (ua) {

    case UNLANG_ACTION_CALCULATE_RESULT:

      break;

    case UNLANG_ACTION_FAIL:

    no_action_fail:

      fr_assert_msg(0, "Function %s (%p) is not allowed to indicate failure via UNLANG_ACTION_FAIL",

              state->repeat_name, REPEAT(state));

      ua = UNLANG_ACTION_CALCULATE_RESULT;

      break;

    default:

      frame_repeat(frame, call_no_result_repeat);

    }

  }

  if (ua == UNLANG_ACTION_FAIL) goto no_action_fail;

done:

  RESTORE_CALLER;

  return ua;

}

/** Call a generic function that produces a result

 *

 * @param[out] p_result   The frame result.

 * @param[in] request   The current request.

 * @param[in] frame   The current frame.

 */

static unlang_action_t call_no_result(UNUSED unlang_result_t *p_result, request_t *request, unlang_stack_frame_t *frame)

{

  unlang_action_t     ua;

  unlang_frame_state_func_t *state = talloc_get_type_abort(frame->state, unlang_frame_state_func_t);

  STORE_CALLER;

  RDEBUG4("Calling function %p (%s)", FUNC(state), state->func_name);

  ua = state->func.nres(request, state->uctx);

  FUNC(state) = NULL;

  state->func_name = NULL;

  if (REPEAT(state)) {

    switch (ua) {

    case UNLANG_ACTION_CALCULATE_RESULT:

      break;

    case UNLANG_ACTION_FAIL:

    no_action_fail:

      fr_assert_msg(0, "Function is not allowed to indicate failure via UNLANG_ACTION_FAIL");

      ua = UNLANG_ACTION_CALCULATE_RESULT;

      break;

    default:

      frame_repeat(frame, call_no_result_repeat);

    }

  }

  if (ua == UNLANG_ACTION_FAIL) goto no_action_fail;

  RESTORE_CALLER;

  return ua;

}

/** Clear pending repeat function calls, and remove the signal handler.

 *

 * The function frame being modified must be at the top of the stack.

 *

 * @param[in] request The current request.

 * @return

 *  - 0 on success.

 *      - -1 on failure.

 */

int unlang_function_clear(request_t *request)

{

  unlang_stack_t      *stack = request->stack;

  unlang_stack_frame_t    *frame = &stack->frame[stack->depth];

  unlang_frame_state_func_t *state;

  if (frame->instruction->type != UNLANG_TYPE_FUNCTION) {

    RERROR("Can't clear function on non-function frame");

    return -1;

  }

  state = talloc_get_type_abort(frame->state, unlang_frame_state_func_t);

  REPEAT(state) = NULL;

  state->signal = NULL;

  repeatable_clear(frame);

  return 0;

}

/** Clear the pending repeat function, and keep the signal handler

 *

 * If a unlang function returns UNLANG_ACTION_CALCULATE_RESULT with a repeat

 * function set, the repeat function is never executed, and the signal handler

 * for the frame (if set) is called to clean up state.

 *

 * If the returning function does not want the cancellation callback to execute

 * it should call `unlang_function_repeat_clear` to clear the repeat function.

 *

 * @param[in] request The current request.

 * @return

 *  - 0 on success.

 *      - -1 on failure.

 */

int unlang_function_repeat_clear(request_t *request)

{

  unlang_stack_t      *stack = request->stack;

  unlang_stack_frame_t    *frame = &stack->frame[stack->depth];

  unlang_frame_state_func_t *state;

  if (frame->instruction->type != UNLANG_TYPE_FUNCTION) {

    RERROR("Can't clear repeat function on non-function frame");

    return -1;

  }

  state = talloc_get_type_abort(frame->state, unlang_frame_state_func_t);

  REPEAT(state) = NULL;

  state->repeat_name = NULL;

  repeatable_clear(frame);

  return 0;

}

/** Set a new signal function for an existing function frame

 *

 * @private

 *

 * The function frame being modified must be at the top of the stack.

 *

 * @param[in] request   The current request.

 * @param[in] signal    The signal function to set.

 * @param[in] sigmask   Signals to block.

 * @param[in] signal_name Name of the signal function call (for debugging).

 * @return

 *  - 0 on success.

 *      - -1 on failure.

 */

int _unlang_function_signal_set(request_t *request, unlang_function_signal_t signal, fr_signal_t sigmask, char const *signal_name)

{

  unlang_stack_t      *stack = request->stack;

  unlang_stack_frame_t    *frame = &stack->frame[stack->depth];

  unlang_frame_state_func_t *state;

  if (frame->instruction->type != UNLANG_TYPE_FUNCTION) {

    RERROR("Can't set repeat function on non-function frame");

    return -1;

  }

  state = talloc_get_type_abort(frame->state, unlang_frame_state_func_t);

  /*

   *  If we're inside unlang_function_call,

   *  it'll pickup state->repeat and do the right thing

   *  once the current function returns.

   */

  state->signal = signal;

  state->sigmask = sigmask;

  state->signal_name = signal_name;

  return 0;

}

/** Set a new repeat function for an existing function frame

 *

 * @private

 *

 * The function frame being modified must be at the top of the stack.

 *

 * @param[in] request   The current request.

 * @param[in] repeat    the repeat function to set.

 * @param[in] repeat_name Name of the repeat function call (for debugging).

 * @param[in] type    Type of repeat function (with or without result).

 * @return

 *  - 0 on success.

 *      - -1 on failure.

 */

int _unlang_function_repeat_set(request_t *request, void *repeat, char const *repeat_name, unlang_function_type_t type)

{

  unlang_stack_t      *stack = request->stack;

  unlang_stack_frame_t    *frame = &stack->frame[stack->depth];

  unlang_frame_state_func_t *state;

  if (frame->instruction->type != UNLANG_TYPE_FUNCTION) {

    RERROR("Can't set repeat function on non-function frame");

    return -1;

  }

  state = talloc_get_type_abort(frame->state, unlang_frame_state_func_t);

  if (unlikely(state->type != type)) {

    fr_assert_msg(0, "Function type mismatch \"%s\"", repeat_name);

    return -1;

  }

  /*

   *  If we're inside unlang_function_call,

   *  it'll pickup state->repeat and do the right thing

   *  once the current function returns.

   */

  REPEAT(state) = repeat;

  state->repeat_name = repeat_name;

  repeatable_set(frame);

  return 0;

}

static inline CC_HINT(always_inline)

unlang_action_t unlang_function_push_common(unlang_result_t *p_result,

              request_t *request,

              void *func,

              char const *func_name,

              void *repeat,

              char const *repeat_name,

              unlang_function_signal_t signal, fr_signal_t sigmask, char const *signal_name,

              unlang_function_type_t type,

              bool top_frame,

              void *uctx)

{

  unlang_stack_t      *stack = request->stack;

  unlang_stack_frame_t    *frame;

  unlang_frame_state_func_t *state;

  if (!func && !repeat) {

    fr_assert_msg(0, "function push must push at least one function!");

    return UNLANG_ACTION_FAIL;

  }

  /*

   *  Push module's function

   */

  if (unlang_interpret_push(p_result, request, &function_instruction,

          FRAME_CONF(RLM_MODULE_NOOP, top_frame), UNLANG_NEXT_STOP) < 0) {

    return UNLANG_ACTION_FAIL;

  }

  frame = &stack->frame[stack->depth];

  /*

   *  Initialize state

   */

  state = frame->state;

  state->signal = signal;

  state->sigmask = sigmask;

  state->signal_name = signal_name;

  state->type = type;

  state->uctx = uctx;

  FUNC(state) = func;

  state->func_name = func_name;

  REPEAT(state) = repeat;

  state->repeat_name = repeat_name;

  if (repeat) repeatable_set(frame); /* execute on the way back up */

  return UNLANG_ACTION_PUSHED_CHILD;

}

/** Push a generic function onto the unlang stack with a result

 *

 * @private

 *

 * These can be pushed by any other type of unlang op to allow a submodule or function

 * deeper in the C call stack to establish a new resumption point.

 *

 * @param[in] p_result    Where to write the result of the function evaluation.

 *

 * @param[in] request   The current request.

 * @param[in] func    to call going up the stack.

 * @param[in] func_name   Name of the function call (for debugging).

 * @param[in] repeat    function to call going back down the stack (may be NULL).

 *        This may be the same as func.

 * @param[in] repeat_name Name of the repeat function call (for debugging).

 * @param[in] signal    function to call if the request is signalled.

 * @param[in] sigmask   Signals to block.

 * @param[in] signal_name Name of the signal function call (for debugging).

 * @param[in] top_frame   Return out of the unlang interpreter when popping this frame.

 * @param[in] uctx    to pass to func(s).

 * @return

 *  - UNLANG_ACTION_PUSHED_CHILD on success.

 *  - UNLANG_ACTION_FAIL on failure.

 */

unlang_action_t _unlang_function_push_with_result(unlang_result_t *p_result,

              request_t *request,

              unlang_function_with_result_t func, char const *func_name,

              unlang_function_with_result_t repeat, char const *repeat_name,

              unlang_function_signal_t signal, fr_signal_t sigmask, char const *signal_name,

              bool top_frame, void *uctx)

{

  unlang_action_t ua;

  unlang_stack_frame_t *frame;

  ua = unlang_function_push_common(p_result,

           request,

           (void *) func, func_name,

           (void *) repeat, repeat_name,

           signal, sigmask, signal_name,

           UNLANG_FUNCTION_TYPE_WITH_RESULT, top_frame, uctx);

  if (unlikely(ua == UNLANG_ACTION_FAIL)) return UNLANG_ACTION_FAIL;

  frame = frame_current(request);

  if (!func && repeat) {

    frame->process = call_with_result_repeat;

  } else {

    frame->process = call_with_result;

  }

  return ua;

}

/** Push a generic function onto the unlang stack

 *

 * @private

 *

 * These can be pushed by any other type of unlang op to allow a submodule or function

 * deeper in the C call stack to establish a new resumption point.

 *

 * @param[in] request   The current request.

 * @param[in] func    to call going up the stack.

 * @param[in] func_name   Name of the function call (for debugging).

 * @param[in] repeat    function to call going back down the stack (may be NULL).

 *        This may be the same as func.

 * @param[in] repeat_name Name of the repeat function call (for debugging).

 * @param[in] signal    function to call if the request is signalled.

 * @param[in] sigmask   Signals to block.

 * @param[in] signal_name Name of the signal function call (for debugging).

 * @param[in] top_frame   Return out of the unlang interpreter when popping this frame.

 * @param[in] uctx    to pass to func(s).

 * @return

 *  - UNLANG_ACTION_PUSHED_CHILD on success.

 *  - UNLANG_ACTION_FAIL on failure.

 */

unlang_action_t _unlang_function_push_no_result(request_t *request,

            unlang_function_no_result_t func, char const *func_name,

            unlang_function_no_result_t repeat, char const *repeat_name,

            unlang_function_signal_t signal, fr_signal_t sigmask, char const *signal_name,

            bool top_frame, void *uctx)

{

  unlang_action_t ua;

  unlang_stack_frame_t *frame;

  ua = unlang_function_push_common(NULL,

           request,

           (void *) func, func_name,

           (void *) repeat, repeat_name,

           signal, sigmask, signal_name,

           UNLANG_FUNCTION_TYPE_NO_RESULT, top_frame, uctx);

  if (unlikely(ua == UNLANG_ACTION_FAIL)) return UNLANG_ACTION_FAIL;

  frame = frame_current(request);

  if (!func && repeat) {

    frame->process = call_no_result_repeat;

  }

  /* frame->process = call_no_result - This is the default, we don't need to set it again */

  return ua;

}

/** Custom frame state dumper

 *

 */

static void unlang_function_dump(request_t *request, unlang_stack_frame_t *frame)

{

  unlang_frame_state_func_t *state = talloc_get_type_abort(frame->state, unlang_frame_state_func_t);

  RDEBUG2("frame state");

  if (FUNC(state))   RDEBUG2("function       %p (%s)", FUNC(state), state->func_name);

  if (REPEAT(state)) RDEBUG2("repeat         %p (%s)", REPEAT(state), state->repeat_name);

  if (state->signal) RDEBUG2("signal         %p (%s)", state->signal, state->signal_name);

}

void unlang_function_init(void)

{

  unlang_register(&(unlang_op_t){

      .name = "function",

      .type = UNLANG_TYPE_FUNCTION,

      .flag = (unlang_op_flag_t)(UNLANG_OP_FLAG_RETURN_POINT | UNLANG_OP_FLAG_INTERNAL),

      .interpret = call_no_result,

      .signal = unlang_function_signal,

      .dump = unlang_function_dump,

      .unlang_size = sizeof(unlang_group_t),

      .unlang_name = "unlang_group_t",

      .frame_state_size = sizeof(unlang_frame_state_func_t),

      .frame_state_type = "unlang_frame_state_func_t",

    });

}