process.h

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#pragma once
/*
 *   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: c333cb62d6046623b3eed23a252c63184306677c $
 *
 * @file src/lib/server/process.h
 * @brief Declarations for functions which process packet state machines
 *
 * This is a convenience header to simplify defining packet processing state machines.
 *
 * The following macros must be defined before this header is included:
 *
 * - PROCESS_INST                       the type of structure that holds instance data for the process module.
 * - PROCESS_PACKET_TYPE                an enum, or generic type (uint32) that can hold
 *                                      all valid packet types.
 * - PROCESS_PACKET_CODE_VALID          the name of a macro or function which accepts one argument
 *                                      and evaluates to true if the packet code is valid.
 *
 * The following macros may (optionally) be defined before this header is included:
 *
 * - PROCESS_CODE_MAX                   the highest valid protocol packet code + 1.
 * - PROCESS_CODE_DO_NOT_RESPOND        The packet code that's used to indicate that no response
 *                                      should be sent.
 * - PROCESS_STATE_EXTRA_FIELDS         extra fields to add to the fr_process_state_t structure.
 *
 * @copyright 2021 The FreeRADIUS server project
 * @copyright 2021 Network RADIUS SAS (legal@networkradius.com)
 */
#ifdef __cplusplus
extern "C" {
#endif
 
#include <freeradius-devel/server/virtual_servers.h>
#include <freeradius-devel/server/pair.h>
#include <freeradius-devel/server/process_types.h>
 
/** Trace each state function as it's entered
 */
#ifndef NDEBUG
#  define PROCESS_TRACE RDEBUG3("Entered state %s", __FUNCTION__)
#else
#  define PROCESS_TRACE
#endif
 
/** Convenience macro for providing CONF_SECTION offsets in section compilation arrays
 *
 */
#ifndef PROCESS_INST
#  error PROCESS_INST must be defined to the C type of the process instance e.g. process_bfd_t
#endif
 
#if defined(PROCESS_RCTX) && defined(PROCESS_RCTX_EXTRA_FIELDS)
#  error Only one of PROCESS_RCTX (the type of the rctx struct) OR PROCESS_RCTX_EXTRA_FIELDS (extra fields for the common rctx struct) can be defined.
#endif
 
#ifndef PROCESS_RCTX
#  define PROCESS_RCTX  process_rctx_t
#endif
 
#ifndef PROCESS_RCTX_RESULT
#  define PROCESS_RCTX_RESULT result
#endif
 
#define PROCESS_CONF_OFFSET(_x) offsetof(PROCESS_INST, sections._x)
#define RESULT_UNUSED           UNUSED
 
#if defined(PROCESS_INST) && defined(PROCESS_PACKET_TYPE) && defined(PROCESS_PACKET_CODE_VALID)
typedef PROCESS_PACKET_TYPE fr_process_rcode_t[RLM_MODULE_NUMCODES];
 
#ifndef PROCESS_STATE_EXTRA_FIELDS
#  define PROCESS_STATE_EXTRA_FIELDS
#endif
 
#ifndef PROCESS_RCTX_EXTRA_FIELDS
#  define PROCESS_RCTX_EXTRA_FIELDS
#endif
/*
 *      Process state machine tables for rcode to packet.
 */
typedef struct {
        PROCESS_PACKET_TYPE     packet_type[RLM_MODULE_NUMCODES];       //!< rcode to packet type mapping.
        PROCESS_PACKET_TYPE     default_reply;  //!< if not otherwise set
        size_t                  section_offset; //!< Where to look in the process instance for
                                                ///< a pointer to the section we should execute.
        rlm_rcode_t             default_rcode;  //!< Default rcode that's set in the frame we used to
                                                ///< evaluate child sections.
        rlm_rcode_t             result_rcode;   //!< Result rcode we return if the virtual server is
                                                ///< being called using the `call` keyword.
        module_method_t         resume;         //!< Function to call after running a recv section.
 
        /*
         *      Each state has only one "recv" or "send".
         */
        union {
                module_method_t         recv;           //!< Method to call when receiving this type of packet.
                module_method_t         send;           //!< Method to call when sending this type of packet.
        };
        PROCESS_STATE_EXTRA_FIELDS
} fr_process_state_t;
 
typedef struct {
        unlang_result_t         result;         //!< Result of the last section executed.
        PROCESS_RCTX_EXTRA_FIELDS
} process_rctx_t;
 
/*
 *      C doesn't technically support forward declaration of static variables.  Until such time as we
 *      rearrange all of the process code, disabling the warnings will have to do.
 *
 *      A real fix is to provide a header file which contains only the macro definitions for the process state
 *      machine.  The process files can include that, then define the function prototypes.  Then define their
 *      own process_state[] state machine, then define the functions.
 */
#ifdef __clang__
DIAG_OFF(tentative-definition-compat)
DIAG_OFF(tentative-definition-incomplete-type)
#endif
 
/*
 *      Some protocols have the same packet codes for requests and replies.
 */
#ifndef PROCESS_SEND_RECV
#define process_state_packet process_state
#define process_state_reply process_state
static fr_process_state_t const process_state[];
#else
static fr_process_state_t const process_state_packet[];
static fr_process_state_t const process_state_reply[];
#endif
 
/*
 *      Process state machine functions
 */
#define UPDATE_STATE_CS(_x) \
do { \
        state = &process_state_ ## _x[request->_x->code]; \
        memcpy(&cs, (CONF_SECTION * const *) (((uint8_t const *) &inst->sections) + state->section_offset), sizeof(cs)); \
} while (0)
 
#define UPDATE_STATE(_x) state = &process_state_ ## _x [request->_x->code]
 
#define PROCESS_ARGS unlang_result_t *p_result, module_ctx_t const *mctx, request_t *request
 
#define RECV(_x) static inline unlang_action_t recv_ ## _x(PROCESS_ARGS)
#define SEND(_x) static inline unlang_action_t send_ ## _x(PROCESS_ARGS)
#define SEND_NO_RESULT(_x) static inline unlang_action_t send_ ## _x(UNUSED PROCESS_ARGS)
#define RESUME(_x) static inline unlang_action_t resume_ ## _x(PROCESS_ARGS)
#define RESUME_FLAG(_x, _p_result_flag, _mctx_flag) static inline unlang_action_t resume_ ## _x(_p_result_flag unlang_result_t *p_result, _mctx_flag module_ctx_t const *mctx, request_t *request)
 
/** Returns the current rcode then resets it for the next module call
 *
 */
static inline CC_HINT(always_inline) unlang_result_t *process_result_reset(unlang_result_t *p_result, fr_process_state_t const *state)
{
        *p_result = UNLANG_RESULT_RCODE(state->default_rcode);
        return p_result;
}
 
#define RESULT_RCODE    (((PROCESS_RCTX *)mctx->rctx)->result.rcode)
#define RESULT_P        process_result_reset(&(((PROCESS_RCTX *)mctx->rctx)->result), state)
 
/** Call a module method with a new rctx
 *
 * @note This should be used to add a rctxs when calling the initial recv section.
 *
 * @param[out] p_result         Pointer to the result code.
 * @param[in] mctx              Module context.
 * @param[in] request           Request.
 * @param[in] method            Method to call.
 * @param[in] rctx              Resume context to use to override the one in the mctx.
 * @return                      Result of the method call.
 */
static inline CC_HINT(always_inline)
unlang_action_t process_with_rctx(unlang_result_t *p_result, module_ctx_t const *mctx,
                                  request_t *request, module_method_t method, void *rctx)
{
        module_ctx_t our_mctx = *mctx;
        our_mctx.rctx = rctx;
 
        return method(p_result, &our_mctx, request);
}
 
/** Call a named recv function directly
 */
#define CALL_RECV(_x) recv_ ## _x(p_result, mctx, request)
 
/** Call a named recv function directly with a new rctx
 */
#define CALL_RECV_RCTX(_x, _rctx) process_with_rctx(p_result, mctx, request, recv_ ## _x, _rctx);
 
/** Call a named send function directly
 */
#define CALL_SEND(_x) send_ ## _x(p_result, mctx, request)
 
/** Call a named resume function directly
 */
#define CALL_RESUME(_x) resume_ ## _x(p_result, mctx, request)
 
/** Call the send function for the current state
 */
#define CALL_SEND_STATE(_state) state->send(p_result, mctx, request)
 
/** Set the current reply code, and call the send function for that state
 */
#define CALL_SEND_TYPE(_x) call_send_type(process_state_reply[(request->reply->code = _x)].send, p_result, mctx, request)
 
static inline unlang_action_t call_send_type(module_method_t send, \
                                             unlang_result_t *p_result, module_ctx_t const *mctx,
                                             request_t *request)
{
        /*
         *      Stupid hack to stop this being honoured
         *      by send_generic.
         */
        pair_delete_reply(attr_packet_type);
        return send(p_result, mctx, request);
}
 
RECV(generic)
{
        CONF_SECTION                    *cs;
        fr_process_state_t const        *state;
        PROCESS_INST                    *inst = mctx->mi->data;
 
        PROCESS_TRACE;
 
        UPDATE_STATE_CS(packet);
 
        if (!state->recv) {
                char const *name;
 
                name = fr_dict_enum_name_by_value(attr_packet_type, fr_box_uint32(request->packet->code));
                if (name) {
                        REDEBUG("Invalid packet type (%s)", name);
                } else {
                        REDEBUG("Invalid packet type (%u)", request->packet->code);
                }
                RETURN_UNLANG_FAIL;
        }
 
        return unlang_module_yield_to_section(RESULT_P, request,
                                              cs, state->default_rcode, state->resume,
                                              NULL, 0, mctx->rctx);
}
 
RESUME(recv_generic)
{
        rlm_rcode_t                     rcode = RESULT_RCODE;
        fr_process_state_t const        *state;
 
        PROCESS_TRACE;
 
        fr_assert(rcode < RLM_MODULE_NUMCODES);
 
        UPDATE_STATE(packet);
 
        request->reply->code = state->packet_type[rcode];
        if (!request->reply->code) request->reply->code = state->default_reply;
#ifdef PROCESS_CODE_DO_NOT_RESPOND
        if (!request->reply->code) request->reply->code = PROCESS_CODE_DO_NOT_RESPOND;
 
#endif
        fr_assert(PROCESS_PACKET_CODE_VALID(request->reply->code));
 
        UPDATE_STATE(reply);
        fr_assert(state->send != NULL);
        return state->send(p_result, mctx, request);
}
 
RESUME_FLAG(recv_no_send,UNUSED,UNUSED)
{
        rlm_rcode_t                     rcode = RESULT_RCODE;
        fr_process_state_t const        *state;
 
        PROCESS_TRACE;
 
        fr_assert(rcode < RLM_MODULE_NUMCODES);
 
        UPDATE_STATE(packet);
 
        request->reply->code = state->packet_type[rcode];
        if (!request->reply->code) request->reply->code = state->default_reply;
#ifdef PROCESS_CODE_DO_NOT_RESPOND
        if (!request->reply->code) request->reply->code = PROCESS_CODE_DO_NOT_RESPOND;
 
#endif
        fr_assert(request->reply->code != 0);
 
        return UNLANG_ACTION_CALCULATE_RESULT;
}
 
SEND_NO_RESULT(generic)
{
        fr_pair_t                       *vp;
        CONF_SECTION                    *cs;
        fr_process_state_t const        *state;
        PROCESS_INST                    *inst = mctx->mi->data;
 
        PROCESS_TRACE;
 
#ifndef NDEBUG
        if (!(
#  ifdef PROCESS_CODE_DO_NOT_RESPOND
            (request->reply->code == PROCESS_CODE_DO_NOT_RESPOND) ||
#  endif
            PROCESS_PACKET_CODE_VALID(request->reply->code))) fr_assert(0);
#endif
 
        UPDATE_STATE_CS(reply);
 
        /*
         *      Allow for over-ride of reply code, IF it's
         *      within range, AND we've pre-compiled the
         *      unlang.
         *
         *      Add reply->packet-type in case we're
         *      being called via the `call {}` keyword.
         *
         *      @todo - enforce that this is an allowed reply for the
         *      request.
         */
        switch (pair_update_reply(&vp, attr_packet_type)) {
        case 0: /* Does not exist */
        update_packet_type:
                vp->vp_uint32 = request->reply->code;
                break;
 
        case 1: /* Exists */
                if (
#ifdef PROCESS_CODE_MAX
                    (vp->vp_uint32 != PROCESS_CODE_MAX) &&
#endif
                    PROCESS_PACKET_CODE_VALID(vp->vp_uint32) &&
                    process_state_reply[vp->vp_uint32].send) {
                        request->reply->code = vp->vp_uint32;
                        UPDATE_STATE_CS(reply);
                        break;
                }
 
                RWDEBUG("Ignoring invalid packet-type reply.%pP", vp);
                goto update_packet_type;
 
        default:
                MEM(0);
        }
 
        if (!cs) {
                char const *name;
 
                name = fr_dict_enum_name_by_value(attr_packet_type, fr_box_uint32(request->reply->code));
                if (name) {
                        RWDEBUG("No 'send %s { ... } section was found.", name);
                } else {
                        RWDEBUG("No 'send %u { ... } section was found.", request->reply->code);
                }
        }
 
        return unlang_module_yield_to_section(RESULT_P, request,
                                              cs, state->default_rcode, state->resume,
                                              NULL, 0, mctx->rctx);
}
 
RESUME(send_generic)
{
        rlm_rcode_t                     rcode = RESULT_RCODE;
        CONF_SECTION                    *cs;
        fr_process_state_t const        *state;
        PROCESS_INST                    *inst = mctx->mi->data;
 
        PROCESS_TRACE;
 
#ifndef NDEBUG
        if (!(
#  ifdef PROCESS_CODE_DO_NOT_RESPOND
            (request->reply->code == PROCESS_CODE_DO_NOT_RESPOND) ||
#  endif
            PROCESS_PACKET_CODE_VALID(request->reply->code))) fr_assert(0);
#endif
        /*
         *      If they delete &reply.Packet-Type, tough for them.
         */
        UPDATE_STATE_CS(reply);
 
        fr_assert(rcode < RLM_MODULE_NUMCODES);
        switch (state->packet_type[rcode]) {
        case 0:                 /* don't change the reply */
                p_result->rcode = state->result_rcode;
                break;
 
        default:
                /*
                 *      If we're in the "do not respond" situation,
                 *      then don't change the packet code to something
                 *      else.  However, if we're in (say) Accept, and
                 *      the code says Reject, then go do reject.
                 *
                 *      The author of the state machine MUST ensure
                 *      that there isn't a loop in the state machine
                 *      definitions.
                 */
                if (
#ifdef PROCESS_CODE_DO_NOT_RESPOND
                    (request->reply->code != PROCESS_CODE_DO_NOT_RESPOND) &&
#endif
                    (state->packet_type[rcode] != request->reply->code)) {
                        char const *old = cf_section_name2(cs);
 
                        request->reply->code = state->packet_type[rcode];
                        UPDATE_STATE_CS(reply);
 
                        RWDEBUG("Failed running 'send %s', changing reply to %s", old, cf_section_name2(cs));
 
                        return unlang_module_yield_to_section(RESULT_P, request,
                                                              cs, state->default_rcode, state->send,
                                                              NULL, 0, mctx->rctx);
                }
                p_result->rcode = state->result_rcode;
 
                fr_assert(!state->packet_type[rcode] || (state->packet_type[rcode] == request->reply->code));
                break;
 
#ifdef PROCESS_CODE_DO_NOT_RESPOND
        case PROCESS_CODE_DO_NOT_RESPOND:
                /*
                 *      There might not be send section defined
                 */
                if (cs) {
                        RDEBUG("The 'send %s' section returned %s - not sending a response",
                               cf_section_name2(cs),
                               fr_table_str_by_value(rcode_table, rcode, "<INVALID>"));
                }
                request->reply->code = PROCESS_CODE_DO_NOT_RESPOND;
                p_result->rcode = state->result_rcode;
                break;
#endif
        }
 
 
        request->reply->timestamp = fr_time();
 
#ifdef PROCESS_CODE_DO_NOT_RESPOND
        /*
         *      Check for "do not respond".
         */
        if (request->reply->code == PROCESS_CODE_DO_NOT_RESPOND) {
                RDEBUG("Not sending reply to client");
                p_result->rcode = RLM_MODULE_HANDLED;
                return UNLANG_ACTION_CALCULATE_RESULT;
        }
#endif
 
        return UNLANG_ACTION_CALCULATE_RESULT;
}
 
#ifdef PROCESS_CODE_DYNAMIC_CLIENT
RESUME_FLAG(new_client_done,,UNUSED)
{
        p_result->rcode = RLM_MODULE_OK;
 
        request->reply->timestamp = fr_time();
 
        return UNLANG_ACTION_CALCULATE_RESULT;
}
 
RESUME(new_client)
{
        rlm_rcode_t                     rcode = RESULT_RCODE;
        CONF_SECTION                    *cs;
        PROCESS_INST const              *inst = mctx->mi->data;
        fr_process_state_t const        *state;
 
        UPDATE_STATE(reply);
 
        switch (rcode) {
        case RLM_MODULE_OK:
        case RLM_MODULE_UPDATED:
                RDEBUG("new client was successful.");
                cs = inst->sections.add_client;
                request->reply->code = PROCESS_CODE_DYNAMIC_CLIENT;
                break;
 
        default:
                RDEBUG("new client was denied.");
                cs = inst->sections.deny_client;
                request->reply->code = PROCESS_CODE_DO_NOT_RESPOND;
                break;
        }
 
        request->component = NULL;
        request->module = NULL;
 
        if (!cs) {
                p_result->rcode = RLM_MODULE_OK;
                request->reply->timestamp = fr_time();
                return UNLANG_ACTION_CALCULATE_RESULT;
        }
 
        return unlang_module_yield_to_section(RESULT_P, request,
                                              cs, RLM_MODULE_FAIL, resume_new_client_done,
                                              NULL, 0, mctx->rctx);
}
 
static inline unlang_action_t new_client(UNUSED unlang_result_t *p_result, module_ctx_t const *mctx, request_t *request)
{
        CONF_SECTION                    *cs;
        PROCESS_INST const              *inst = mctx->mi->data;
        fr_process_state_t const        *state;
 
        UPDATE_STATE(packet);
 
        PROCESS_TRACE;
        fr_assert(inst->sections.new_client != NULL);
        cs = inst->sections.new_client;
 
        return unlang_module_yield_to_section(RESULT_P, request,
                                              cs, RLM_MODULE_FAIL, resume_new_client,
                                              NULL, 0, mctx->rctx);
}
 
#define DYNAMIC_CLIENT_SECTIONS \
        { \
                .section = SECTION_NAME("new", "client"), \
                .actions = &mod_actions_authorize, \
                .offset = PROCESS_CONF_OFFSET(new_client), \
        }, \
        { \
                .section = SECTION_NAME("add", "client"), \
                .actions = &mod_actions_authorize, \
                .offset = PROCESS_CONF_OFFSET(add_client), \
        }, \
        { \
                .section = SECTION_NAME("deny", "client"), \
                .actions = &mod_actions_authorize, \
                .offset = PROCESS_CONF_OFFSET(deny_client), \
        }
 
#endif  /* PROCESS_DYNAMIC_CLIENT */
 
#endif  /* defined(PROCESS_INST) && defined(PROCESS_PACKET_TYPE) && defined(PROCESS_PACKET_CODE_VALID) */
 
#ifdef __cplusplus
}
#endif