xlat_func.c

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/*
 *   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: 4ce620fd72d54fafe0e94993d07a86eb0e9683ab $
 *
 * @file xlat_func.c
 * @brief Registration API for xlat functions
 *
 * @copyright 2023 Arran Cudbard-Bell (a.cudbardb@freeradius.org)
 */
 
RCSID("$Id: 4ce620fd72d54fafe0e94993d07a86eb0e9683ab $")
 
#include <freeradius-devel/server/module_rlm.h>
#include <freeradius-devel/unlang/xlat_priv.h>
#include <freeradius-devel/unlang/xlat.h>
#include <freeradius-devel/unlang/xlat_func.h>
 
static fr_rb_tree_t *xlat_root = NULL;
 
/** Compare two xlat_t by the registered name
 *
 * @param[in] one               First xlat_t to compare.
 * @param[in] two               Second xlat_t to compare.
 * @return
 *      - -1 if one < two
 *      - 0 if one == two
 *      - 1 if one > two
 */
static int8_t xlat_name_cmp(void const *one, void const *two)
{
        xlat_t const *a = one, *b = two;
        size_t a_len, b_len;
        int ret;
 
        a_len = strlen(a->name);
        b_len = strlen(b->name);
 
        ret = CMP(a_len, b_len);
        if (ret != 0) return ret;
 
        ret = memcmp(a->name, b->name, a_len);
        return CMP(ret, 0);
}
 
/** Compare two xlat_t by the underlying function
 *
 * @param[in] one               First xlat_t to compare.
 * @param[in] two               Second xlat_t to compare.
 * @return
 *      - -1 if one < two
 *      - 0 if one == two
 *      - 1 if one > two
 */
int8_t xlat_func_cmp(void const *one, void const *two)
{
        xlat_t const *a = one, *b = two;
 
        return CMP((uintptr_t)a->func, (uintptr_t)b->func);
}
 
/*
 *      find the appropriate registered xlat function.
 */
xlat_t *xlat_func_find(char const *in, ssize_t inlen)
{
        char buffer[256];
 
        if (!xlat_root) return NULL;
 
        if (inlen < 0) return fr_rb_find(xlat_root, &(xlat_t){ .name = in });
 
        if ((size_t) inlen >= sizeof(buffer)) return NULL;
 
        memcpy(buffer, in, inlen);
        buffer[inlen] = '\0';
 
        return fr_rb_find(xlat_root, &(xlat_t){ .name = buffer });
}
 
/** Remove an xlat function from the function tree
 *
 * @param[in] xlat      to free.
 * @return 0
 */
static int _xlat_func_talloc_free(xlat_t *xlat)
{
        if (!xlat_root) return 0;
 
        fr_rb_delete(xlat_root, xlat);
        if (fr_rb_num_elements(xlat_root) == 0) TALLOC_FREE(xlat_root);
 
        return 0;
}
 
 
/** Callback for the rbtree to clear out any xlats still registered
 *
 */
static void _xlat_func_tree_free(void *xlat)
{
        talloc_free(xlat);
}
 
#if 0
/** Compare two argument entries to see if they're equivalent
 *
 * @note Does not check escape function or uctx pointers.
 *
 * @param[in] a         First argument structure.
 * @param[in] b         Second argument structure.
 * @return
 *      - 1 if a > b
 *      - 0 if a == b
 *      - -1 if a < b
 */
static int xlat_arg_cmp_no_escape(xlat_arg_parser_t const *a, xlat_arg_parser_t const *b)
{
        int8_t ret;
 
        ret = CMP(a->required, b->required);
        if (ret != 0) return ret;
 
        ret = CMP(a->concat, b->concat);
        if (ret != 0) return ret;
 
        ret = CMP(a->single, b->single);
        if (ret != 0) return ret;
 
        ret = CMP(a->variadic, b->variadic);
        if (ret != 0) return ret;
 
        ret = CMP(a->always_escape, b->always_escape);
        if (ret != 0) return ret;
 
        return CMP(a->type, b->type);
}
 
/** Compare two argument lists to see if they're equivalent
 *
 * @note Does not check escape function or uctx pointers.
 *
 * @param[in] a         First argument structure.
 * @param[in] b         Second argument structure.
 * @return
 *      - 1 if a > b
 *      - 0 if a == b
 *      - -1 if a < b
 */
static int xlat_arg_cmp_list_no_escape(xlat_arg_parser_t const a[], xlat_arg_parser_t const b[])
{
        xlat_arg_parser_t const *arg_a_p;
        xlat_arg_parser_t const *arg_b_p;
 
        for (arg_a_p = a, arg_b_p = b;
             (arg_a_p->type != FR_TYPE_NULL) && (arg_b_p->type != FR_TYPE_NULL);
             arg_a_p++, arg_b_p++) {
                int8_t ret;
 
                ret = xlat_arg_cmp_no_escape(arg_a_p, arg_b_p);
                if (ret != 0) return ret;
        }
 
        return CMP(arg_a_p, arg_b_p);   /* Check we ended at the same point */
}
#endif
 
xlat_t *xlat_func_find_module(module_inst_ctx_t const *mctx, char const *name)
{
        char inst_name[256];
 
        fr_assert(xlat_root);
 
        if (!*name) {
                ERROR("%s: Invalid xlat name", __FUNCTION__);
                return NULL;
        }
 
        /*
         *      Name xlats other than those which are just the module instance
         *      as <instance name>.<function name>
         */
        if (mctx && name != mctx->mi->name) {
                snprintf(inst_name, sizeof(inst_name), "%s.%s", mctx->mi->name, name);
                name = inst_name;
        }
 
        /*
         *      If it already exists, replace the instance.
         */
        return fr_rb_find(xlat_root, &(xlat_t){ .name = name });
}
 
/** Register an xlat function
 *
 * @param[in] ctx               Used to automate deregistration of the xlat function.
 * @param[in] name              of the xlat.
 * @param[in] func              to register.
 * @param[in] return_type       what type of output the xlat function will produce.
 * @return
 *      - A handle for the newly registered xlat function on success.
 *      - NULL on failure.
 */
xlat_t *xlat_func_register(TALLOC_CTX *ctx, char const *name, xlat_func_t func, fr_type_t return_type)
{
        xlat_t  *c;
        fr_sbuff_t in;
        size_t len, used;
 
        fr_assert(xlat_root);
 
        if (!*name) {
        invalid_name:
                ERROR("%s: Invalid xlat name", __FUNCTION__);
                return NULL;
        }
 
        len = strlen(name);
        if ((len == 1) && (strchr("InscCdDeGHlmMStTY", *name) != NULL)) goto invalid_name;
 
        in = FR_SBUFF_IN(name, len);
        fr_sbuff_adv_past_allowed(&in, SIZE_MAX, xlat_func_chars, NULL);
        used = fr_sbuff_used(&in);
 
        if (used < len) {
                ERROR("%s: Invalid character '%c' in dynamic expansion name '%s'", __FUNCTION__, name[used], name);
                return NULL;
        }
 
        /*
         *      If it already exists, replace the instance.
         */
        c = fr_rb_find(xlat_root, &(xlat_t){ .name = name });
        if (c) {
                if (c->internal) {
                        ERROR("%s: Cannot re-define internal expansion %s", __FUNCTION__, name);
                        return NULL;
                }
 
                if (c->func != func) {
                        ERROR("%s: Cannot change callback function for %s", __FUNCTION__, name);
                        return NULL;
                }
 
                return c;
        }
 
        /*
         *      Doesn't exist.  Create it.
         */
        MEM(c = talloc(NULL, xlat_t));
        *c = (xlat_t){
                .name = talloc_typed_strdup(c, name),
                .func = func,
                .return_type = return_type,
                .input_type = XLAT_INPUT_UNPROCESSED    /* set default - will be overridden if args are registered */
        };
 
        /*
         *      Don't allocate directly in the parent ctx, it might be mprotected
         *      later, and that'll cause segfaults if any of the xlat_t are still
         *      protected when we start shuffling the contents of the rbtree.
         */
        if (ctx) talloc_link_ctx(c, ctx);
 
        talloc_set_destructor(c, _xlat_func_talloc_free);
        DEBUG3("%s: %s", __FUNCTION__, c->name);
 
        if (fr_rb_replace(NULL, xlat_root, c) < 0) {
                ERROR("%s: Failed inserting xlat registration for %s", __FUNCTION__, c->name);
                talloc_free(c);
                return NULL;
        }
 
        return c;
}
 
/** Associate a module calling ctx with the xlat
 *
 * @note Intended to be called from the module_rlm
 *
 * @param[in] x         to set the mctx for.
 * @param[in] mctx      Is duplicated and about to the lifetime of the xlat.
 */
void xlat_mctx_set(xlat_t *x, module_inst_ctx_t const *mctx)
{
        module_inst_ctx_t       *our_mctx = NULL;
 
        TALLOC_FREE(x->mctx);
        MEM(our_mctx = talloc_zero(x, module_inst_ctx_t));      /* Original won't stick around */
        memcpy(our_mctx, mctx, sizeof(*our_mctx));
        x->mctx = our_mctx;
}
 
/** Verify xlat arg specifications are valid
 *
 * @param[in] x         we're setting arguments for.
 * @param[in] arg       specification to validate.
 * @param[in] last      Is this the last argument in the list.
 */
static inline int xlat_arg_parser_validate(xlat_t *x, xlat_arg_parser_t const *arg, bool last)
{
        if (arg->concat) {
                if (!fr_cond_assert_msg((arg->type == FR_TYPE_STRING) || (arg->type == FR_TYPE_OCTETS),
                                        "%s - concat type must be string or octets", x->name)) return -1;
 
                if (!fr_cond_assert_msg(!arg->single, "%s - concat and single are mutually exclusive", x->name)) return -1;
        }
 
        if (arg->single) {
                if (!fr_cond_assert_msg(!arg->concat, "%s - single and concat are mutually exclusive", x->name)) return -1;
        }
 
        if (arg->variadic) {
                if (!fr_cond_assert_msg(last, "%s - variadic can only be set on the last argument", x->name)) return -1;
                if (!fr_cond_assert_msg(!arg->required, "%s - required can't be set on a variadic argument. "
                                        "Set required in the preceding entry", x->name)) return -1;
        }
 
        if (arg->always_escape) {
                if (!fr_cond_assert_msg(arg->func, "%s - always_escape requires an escape func", x->name)) return -1;
        }
 
        if (arg->uctx) {
                if (!fr_cond_assert_msg(arg->func, "%s - uctx requires an escape func", x->name)) return -1;
        }
 
        switch (arg->type) {
        case FR_TYPE_LEAF:
        case FR_TYPE_VOID:
                break;
 
        default:
                fr_assert_fail("%s - type must be a leaf box type", x->name);
                return -1;
        }
 
        return 0;
}
 
/** Register the arguments of an xlat
 *
 * For xlats that take multiple arguments
 *
 * @param[in,out] x             to have it's arguments registered
 * @param[in] args              to be registered
 * @return
 *      - 0 on success.
 *      - < 0 on failure.
 */
int xlat_func_args_set(xlat_t *x, xlat_arg_parser_t const args[])
{
        xlat_arg_parser_t const *arg_p = args;
        bool                    seen_optional = false;
 
        for (arg_p = args; arg_p->type != FR_TYPE_NULL; arg_p++) {
                if (xlat_arg_parser_validate(x, arg_p, (arg_p + 1)->type == FR_TYPE_NULL) < 0) return -1;
 
                if (arg_p->required) {
                        if (!fr_cond_assert_msg(!seen_optional,
                                                "required arguments must be at the "
                                                "start of the argument list")) return -1;
                } else {
                        seen_optional = true;
                }
        }
        x->args = args;
        x->input_type = XLAT_INPUT_ARGS;
 
        return 0;
}
 
/** Register call environment of an xlat
 *
 * @param[in,out] x             to have it's module method env registered.
 * @param[in] env_method        to be registered.
 */
void xlat_func_call_env_set(xlat_t *x, call_env_method_t const *env_method)
{
        x->call_env_method = env_method;
}
 
/** Specify flags that alter the xlat's behaviour
 *
 * @param[in] x                 xlat to set flags for.
 * @param[in] flags             to set.
 */
void xlat_func_flags_set(xlat_t *x, xlat_func_flags_t flags)
{
        x->flags.pure = flags & XLAT_FUNC_FLAG_PURE;
        x->internal = flags & XLAT_FUNC_FLAG_INTERNAL;
        x->flags.impure_func = !x->flags.pure;
}
 
/** Set a print routine for an xlat function.
 *
 * @param[in] xlat to set
 * @param[in] func for printing
 */
void xlat_func_print_set(xlat_t *xlat, xlat_print_t func)
{
        xlat->print = func;
}
 
/** Set a resolve routine for an xlat function.
 *
 * @param[in] xlat to set
 * @param[in] func to resolve xlat.
 */
void xlat_func_resolve_set(xlat_t *xlat, xlat_resolve_t func)
{
        xlat->resolve = func;
}
 
/** Set a resolve routine for an xlat function.
 *
 * @param[in] xlat to set
 * @param[in] func to purify xlat
 */
void xlat_purify_func_set(xlat_t *xlat, xlat_purify_t func)
{
        xlat->purify = func;
}
 
/** Set the escaped values for output boxes
 *
 * @param[in] xlat              function to set the escaped value for (as returned by xlat_register).
 * @param[in] safe_for          escaped value to write to output boxes.
 */
void _xlat_func_safe_for_set(xlat_t *xlat, fr_value_box_safe_for_t safe_for)
{
        xlat->return_safe_for = safe_for;
}
 
/** Set global instantiation/detach callbacks
 *
 * @param[in] xlat              to set instantiation callbacks for.
 * @param[in] instantiate       Instantiation function. Called whenever a xlat is
 *                              compiled.
 * @param[in] inst_type         Name of the instance structure.
 * @param[in] inst_size         The size of the instance struct.
 *                              Pre-allocated for use by the instantiate function.
 *                              If 0, no memory will be allocated.
 * @param[in] detach            Called when an xlat_exp_t is freed.
 * @param[in] uctx              Passed to the instantiation function.
 */
void _xlat_func_instantiate_set(xlat_t const *xlat,
                                 xlat_instantiate_t instantiate, char const *inst_type, size_t inst_size,
                                 xlat_detach_t detach,
                                 void *uctx)
{
        xlat_t *c = UNCONST(xlat_t *, xlat);
 
        c->instantiate = instantiate;
        c->inst_type = inst_type;
        c->inst_size = inst_size;
        c->detach = detach;
        c->uctx = uctx;
}
 
/** Register an async xlat
 *
 * All functions registered must be !pure
 *
 * @param[in] xlat                      to set instantiation callbacks for.
 * @param[in] thread_instantiate        Instantiation function. Called for every compiled xlat
 *                                      every time a thread is started.
 * @param[in] thread_inst_type          Name of the thread instance structure.
 * @param[in] thread_inst_size          The size of the thread instance struct.
 *                                      Pre-allocated for use by the instantiate function.
 *                                      If 0, no memory will be allocated.
 * @param[in] thread_detach             Called when the thread is freed.
 * @param[in] uctx                      Passed to the thread instantiate function.
 */
void _xlat_func_thread_instantiate_set(xlat_t const *xlat,
                                        xlat_thread_instantiate_t thread_instantiate,
                                        char const *thread_inst_type, size_t thread_inst_size,
                                        xlat_thread_detach_t thread_detach,
                                        void *uctx)
{
        xlat_t *c = UNCONST(xlat_t *, xlat);
 
        /*
         *      Pure functions can't use any thread-local
         *      variables. They MUST operate only on constant
         *      instantiation data, and on their (possibly constant)
         *      inputs.
         */
        fr_assert(!c->flags.pure);
 
        c->thread_instantiate = thread_instantiate;
        c->thread_inst_type = thread_inst_type;
        c->thread_inst_size = thread_inst_size;
        c->thread_detach = thread_detach;
        c->thread_uctx = uctx;
}
 
/** Unregister an xlat function
 *
 * We can only have one function to call per name, so the passing of "func"
 * here is extraneous.
 *
 * @param[in] name xlat to unregister.
 */
void xlat_func_unregister(char const *name)
{
        xlat_t  *c;
 
        if (!name || !xlat_root) return;
 
        c = fr_rb_find(xlat_root, &(xlat_t){ .name = name });
        if (!c) return;
 
        (void) talloc_get_type_abort(c, xlat_t);
 
        talloc_free(c); /* Should also remove from tree */
}
 
void xlat_func_unregister_module(module_instance_t const *inst)
{
        xlat_t                          *c;
        fr_rb_iter_inorder_t    iter;
 
        if (!xlat_root) return; /* All xlats have already been freed */
 
        for (c = fr_rb_iter_init_inorder(&iter, xlat_root);
             c;
             c = fr_rb_iter_next_inorder(&iter)) {
                if (!c->mctx) continue;
                if (c->mctx->mi != inst) continue;
 
                fr_rb_iter_delete_inorder(&iter);
        }
}
 
int xlat_func_init(void)
{
        if (xlat_root) return 0;
 
        /*
         *      Create the function tree
         */
        xlat_root = fr_rb_inline_talloc_alloc(NULL, xlat_t, func_node, xlat_name_cmp, _xlat_func_tree_free);
        if (!xlat_root) {
                ERROR("%s: Failed to create tree", __FUNCTION__);
                return -1;
        }
 
        return 0;
}
 
void xlat_func_free(void)
{
        fr_rb_tree_t *xr = xlat_root;           /* Make sure the tree can't be freed multiple times */
 
        if (!xr) return;
 
        xlat_root = NULL;
        talloc_free(xr);
}