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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-27 06:33:50 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-27 06:33:50 +0000 |
commit | fe39ffb8b90ae4e002ed73fe98617cd590abb467 (patch) | |
tree | b80e5956907d8aeaaffe4e4f0c068c0e6157ce8b /include/ap_expr.h | |
parent | Initial commit. (diff) | |
download | apache2-upstream.tar.xz apache2-upstream.zip |
Adding upstream version 2.4.56.upstream/2.4.56upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'include/ap_expr.h')
-rw-r--r-- | include/ap_expr.h | 353 |
1 files changed, 353 insertions, 0 deletions
diff --git a/include/ap_expr.h b/include/ap_expr.h new file mode 100644 index 0000000..8e57fcd --- /dev/null +++ b/include/ap_expr.h @@ -0,0 +1,353 @@ +/* Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. + * The ASF licenses this file to You under the Apache License, Version 2.0 + * (the "License"); you may not use this file except in compliance with + * the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +/** + * @file ap_expr.h + * @brief Expression parser + * + * @defgroup AP_EXPR Expression parser + * @ingroup APACHE_CORE + * @{ + */ + +#ifndef AP_EXPR_H +#define AP_EXPR_H + +#include "httpd.h" +#include "http_config.h" +#include "ap_regex.h" + +#ifdef __cplusplus +extern "C" { +#endif + +/** A node in the expression parse tree */ +typedef struct ap_expr_node ap_expr_t; + +/** Struct describing a parsed expression */ +typedef struct { + /** The root of the actual expression parse tree */ + ap_expr_t *root_node; + /** The filename where the expression has been defined (for logging). + * May be NULL + */ + const char *filename; + /** The line number where the expression has been defined (for logging). */ + unsigned int line_number; + /** Flags relevant for the expression, see AP_EXPR_FLAG_* */ + unsigned int flags; + /** The module that is used for loglevel configuration */ + int module_index; +} ap_expr_info_t; + +/** Use ssl_expr compatibility mode (changes the meaning of the comparison + * operators) + */ +#define AP_EXPR_FLAG_SSL_EXPR_COMPAT 1 +/** Don't add significant request headers to the Vary response header */ +#define AP_EXPR_FLAG_DONT_VARY 2 +/** Don't allow functions/vars that bypass the current request's access + * restrictions or would otherwise leak confidential information. + * Used by e.g. mod_include. + */ +#define AP_EXPR_FLAG_RESTRICTED 4 +/** Expression evaluates to a string, not to a bool */ +#define AP_EXPR_FLAG_STRING_RESULT 8 + + +/** + * Evaluate a parse tree, simple interface + * @param r The current request + * @param expr The expression to be evaluated + * @param err Where an error message should be stored + * @return > 0 if expression evaluates to true, == 0 if false, < 0 on error + * @note err will be set to NULL on success, or to an error message on error + * @note request headers used during evaluation will be added to the Vary: + * response header, unless ::AP_EXPR_FLAG_DONT_VARY is set. + */ +AP_DECLARE(int) ap_expr_exec(request_rec *r, const ap_expr_info_t *expr, + const char **err); + +/** + * Evaluate a parse tree, with access to regexp backreference + * @param r The current request + * @param expr The expression to be evaluated + * @param nmatch size of the regex match vector pmatch + * @param pmatch information about regex matches + * @param source the string that pmatch applies to + * @param err Where an error message should be stored + * @return > 0 if expression evaluates to true, == 0 if false, < 0 on error + * @note err will be set to NULL on success, or to an error message on error + * @note nmatch/pmatch/source can be used both to make previous matches + * available to ap_expr_exec_re and to use ap_expr_exec_re's matches + * later on. + * @note request headers used during evaluation will be added to the Vary: + * response header, unless ::AP_EXPR_FLAG_DONT_VARY is set. + */ +AP_DECLARE(int) ap_expr_exec_re(request_rec *r, const ap_expr_info_t *expr, + apr_size_t nmatch, ap_regmatch_t *pmatch, + const char **source, const char **err); + +/** Context used during evaluation of a parse tree, created by ap_expr_exec */ +typedef struct { + /** the current request */ + request_rec *r; + /** the current connection */ + conn_rec *c; + /** the current virtual host */ + server_rec *s; + /** the pool to use */ + apr_pool_t *p; + /** where to store the error string */ + const char **err; + /** ap_expr_info_t for the expression */ + const ap_expr_info_t *info; + /** regex match information for back references */ + ap_regmatch_t *re_pmatch; + /** size of the vector pointed to by re_pmatch */ + apr_size_t re_nmatch; + /** the string corresponding to the re_pmatch */ + const char **re_source; + /** A string where the comma separated names of headers are stored + * to be later added to the Vary: header. If NULL, the caller is not + * interested in this information. + */ + const char **vary_this; + /** where to store the result string */ + const char **result_string; + /** Arbitrary context data provided by the caller for custom functions */ + void *data; + /** The current recursion level */ + int reclvl; +} ap_expr_eval_ctx_t; + +/** + * Evaluate a parse tree, full featured version + * @param ctx The evaluation context with all data filled in + * @return > 0 if expression evaluates to true, == 0 if false, < 0 on error + * @note *ctx->err will be set to NULL on success, or to an error message on + * error + * @note request headers used during evaluation will be added to the Vary: + * response header if ctx->vary_this is set. + */ +AP_DECLARE(int) ap_expr_exec_ctx(ap_expr_eval_ctx_t *ctx); + +/** + * Evaluate a parse tree of a string valued expression + * @param r The current request + * @param expr The expression to be evaluated + * @param err Where an error message should be stored + * @return The result string, NULL on error + * @note err will be set to NULL on success, or to an error message on error + * @note request headers used during evaluation will be added to the Vary: + * response header, unless ::AP_EXPR_FLAG_DONT_VARY is set. + */ +AP_DECLARE(const char *) ap_expr_str_exec(request_rec *r, + const ap_expr_info_t *expr, + const char **err); + +/** + * Evaluate a parse tree of a string valued expression + * @param r The current request + * @param expr The expression to be evaluated + * @param nmatch size of the regex match vector pmatch + * @param pmatch information about regex matches + * @param source the string that pmatch applies to + * @param err Where an error message should be stored + * @return The result string, NULL on error + * @note err will be set to NULL on success, or to an error message on error + * @note nmatch/pmatch/source can be used both to make previous matches + * available to ap_expr_exec_re and to use ap_expr_exec_re's matches + * later on. + * @note request headers used during evaluation will be added to the Vary: + * response header, unless ::AP_EXPR_FLAG_DONT_VARY is set. + */ +AP_DECLARE(const char *) ap_expr_str_exec_re(request_rec *r, + const ap_expr_info_t *expr, + apr_size_t nmatch, + ap_regmatch_t *pmatch, + const char **source, + const char **err); + + +/** + * The parser can be extended with variable lookup, functions, and + * and operators. + * + * During parsing, the parser calls the lookup function to resolve a + * name into a function pointer and an opaque context for the function. + * If the argument to a function or operator is constant, the lookup function + * may also parse that argument and store the parsed data in the context. + * + * The default lookup function is the hook ::ap_expr_lookup_default which just + * calls ap_run_expr_lookup. Modules can use it to make functions and + * variables generally available. + * + * An ap_expr consumer can also provide its own custom lookup function to + * modify the set of variables and functions that are available. The custom + * lookup function can in turn call 'ap_run_expr_lookup'. + */ + +/** Unary operator, takes one string argument and returns a bool value. + * The name must have the form '-z' (one letter only). + * @param ctx The evaluation context + * @param data An opaque context provided by the lookup hook function + * @param arg The (right) operand + * @return 0 or 1 + */ +typedef int ap_expr_op_unary_t(ap_expr_eval_ctx_t *ctx, const void *data, + const char *arg); + +/** Binary operator, takes two string arguments and returns a bool value. + * The name must have the form '-cmp' (at least two letters). + * @param ctx The evaluation context + * @param data An opaque context provided by the lookup hook function + * @param arg1 The left operand + * @param arg2 The right operand + * @return 0 or 1 + */ +typedef int ap_expr_op_binary_t(ap_expr_eval_ctx_t *ctx, const void *data, + const char *arg1, const char *arg2); + +/** String valued function, takes a string argument and returns a string + * @param ctx The evaluation context + * @param data An opaque context provided by the lookup hook function + * @param arg The argument + * @return The functions result string, may be NULL for 'empty string' + */ +typedef const char *(ap_expr_string_func_t)(ap_expr_eval_ctx_t *ctx, + const void *data, + const char *arg); + +/** List valued function, takes a string argument and returns a list of strings + * Can currently only be called following the builtin '-in' operator. + * @param ctx The evaluation context + * @param data An opaque context provided by the lookup hook function + * @param arg The argument + * @return The functions result list of strings, may be NULL for 'empty array' + */ +typedef apr_array_header_t *(ap_expr_list_func_t)(ap_expr_eval_ctx_t *ctx, + const void *data, + const char *arg); + +/** Variable lookup function, takes no argument and returns a string + * @param ctx The evaluation context + * @param data An opaque context provided by the lookup hook function + * @return The expanded variable + */ +typedef const char *(ap_expr_var_func_t)(ap_expr_eval_ctx_t *ctx, + const void *data); + +/** parameter struct passed to the lookup hook functions */ +typedef struct { + /** type of the looked up object */ + int type; +#define AP_EXPR_FUNC_VAR 0 +#define AP_EXPR_FUNC_STRING 1 +#define AP_EXPR_FUNC_LIST 2 +#define AP_EXPR_FUNC_OP_UNARY 3 +#define AP_EXPR_FUNC_OP_BINARY 4 + /** name of the looked up object */ + const char *name; + + int flags; + + apr_pool_t *pool; + apr_pool_t *ptemp; + + /** where to store the function pointer */ + const void **func; + /** where to store the function's context */ + const void **data; + /** where to store the error message (if any) */ + const char **err; + + /** arg for pre-parsing (only if a simple string). + * For binary ops, this is the right argument. */ + const char *arg; +} ap_expr_lookup_parms; + +/** Function for looking up the provider function for a variable, operator + * or function in an expression. + * @param parms The parameter struct, also determines where the result is + * stored. + * @return OK on success, + * !OK on failure, + * DECLINED if the requested name is not handled by this function + */ +typedef int (ap_expr_lookup_fn_t)(ap_expr_lookup_parms *parms); + +/** Default lookup function which just calls ap_run_expr_lookup(). + * ap_run_expr_lookup cannot be used directly because it has the wrong + * calling convention under Windows. + */ +AP_DECLARE_NONSTD(int) ap_expr_lookup_default(ap_expr_lookup_parms *parms); + +AP_DECLARE_HOOK(int, expr_lookup, (ap_expr_lookup_parms *parms)) + +/** + * Parse an expression into a parse tree + * @param pool Pool + * @param ptemp temp pool + * @param info The ap_expr_info_t struct (with values filled in) + * @param expr The expression string to parse + * @param lookup_fn The lookup function to use, NULL for default + * @return NULL on success, error message on error. + * A pointer to the resulting parse tree will be stored in + * info->root_node. + */ +AP_DECLARE(const char *) ap_expr_parse(apr_pool_t *pool, apr_pool_t *ptemp, + ap_expr_info_t *info, const char *expr, + ap_expr_lookup_fn_t *lookup_fn); + +/** + * High level interface to ap_expr_parse that also creates ap_expr_info_t and + * uses info from cmd_parms to fill in most of it. + * @param cmd The cmd_parms struct + * @param expr The expression string to parse + * @param flags The flags to use, see AP_EXPR_FLAG_* + * @param err Set to NULL on success, error message on error + * @param lookup_fn The lookup function used to lookup vars, functions, and + * operators + * @param module_index The module_index to set for the expression + * @return The parsed expression + * @note Usually ap_expr_parse_cmd() should be used + */ +AP_DECLARE(ap_expr_info_t *) ap_expr_parse_cmd_mi(const cmd_parms *cmd, + const char *expr, + unsigned int flags, + const char **err, + ap_expr_lookup_fn_t *lookup_fn, + int module_index); + +/** + * Convenience wrapper for ap_expr_parse_cmd_mi() that sets + * module_index = APLOG_MODULE_INDEX + */ +#define ap_expr_parse_cmd(cmd, expr, flags, err, lookup_fn) \ + ap_expr_parse_cmd_mi(cmd, expr, flags, err, lookup_fn, APLOG_MODULE_INDEX) + + /** + * Internal initialisation of ap_expr (for httpd internal use) + */ +void ap_expr_init(apr_pool_t *pool); + +#ifdef __cplusplus +} +#endif + +#endif /* AP_EXPR_H */ +/** @} */ |