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diff --git a/include/util_filter.h b/include/util_filter.h new file mode 100644 index 0000000..5a96607 --- /dev/null +++ b/include/util_filter.h @@ -0,0 +1,639 @@ +/* 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 util_filter.h + * @brief Apache filter library + */ + +#ifndef AP_FILTER_H +#define AP_FILTER_H + +#include "apr.h" +#include "apr_buckets.h" + +#include "httpd.h" + +#if APR_HAVE_STDARG_H +#include <stdarg.h> +#endif + +#ifdef __cplusplus +extern "C" { +#endif + +/** + * @brief input filtering modes + */ +typedef enum { + /** The filter should return at most readbytes data. */ + AP_MODE_READBYTES, + /** The filter should return at most one line of CRLF data. + * (If a potential line is too long or no CRLF is found, the + * filter may return partial data). + */ + AP_MODE_GETLINE, + /** The filter should implicitly eat any CRLF pairs that it sees. */ + AP_MODE_EATCRLF, + /** The filter read should be treated as speculative and any returned + * data should be stored for later retrieval in another mode. */ + AP_MODE_SPECULATIVE, + /** The filter read should be exhaustive and read until it can not + * read any more. + * Use this mode with extreme caution. + */ + AP_MODE_EXHAUSTIVE, + /** The filter should initialize the connection if needed, + * NNTP or FTP over SSL for example. + */ + AP_MODE_INIT +} ap_input_mode_t; + +/** + * @defgroup APACHE_CORE_FILTER Filter Chain + * @ingroup APACHE_CORE + * + * Filters operate using a "chaining" mechanism. The filters are chained + * together into a sequence. When output is generated, it is passed through + * each of the filters on this chain, until it reaches the end (or "bottom") + * and is placed onto the network. + * + * The top of the chain, the code generating the output, is typically called + * a "content generator." The content generator's output is fed into the + * filter chain using the standard Apache output mechanisms: ap_rputs(), + * ap_rprintf(), ap_rwrite(), etc. + * + * Each filter is defined by a callback. This callback takes the output from + * the previous filter (or the content generator if there is no previous + * filter), operates on it, and passes the result to the next filter in the + * chain. This pass-off is performed using the ap_fc_* functions, such as + * ap_fc_puts(), ap_fc_printf(), ap_fc_write(), etc. + * + * When content generation is complete, the system will pass an "end of + * stream" marker into the filter chain. The filters will use this to flush + * out any internal state and to detect incomplete syntax (for example, an + * unterminated SSI directive). + * + * @{ + */ + +/* forward declare the filter type */ +typedef struct ap_filter_t ap_filter_t; + +/** + * @name Filter callbacks + * + * This function type is used for filter callbacks. It will be passed a + * pointer to "this" filter, and a "bucket brigade" containing the content + * to be filtered. + * + * In filter->ctx, the callback will find its context. This context is + * provided here, so that a filter may be installed multiple times, each + * receiving its own per-install context pointer. + * + * Callbacks are associated with a filter definition, which is specified + * by name. See ap_register_input_filter() and ap_register_output_filter() + * for setting the association between a name for a filter and its + * associated callback (and other information). + * + * If the initialization function argument passed to the registration + * functions is non-NULL, it will be called iff the filter is in the input + * or output filter chains and before any data is generated to allow the + * filter to prepare for processing. + * + * The bucket brigade always belongs to the caller, but the filter + * is free to use the buckets within it as it sees fit. Normally, + * the brigade will be returned empty. Buckets *may not* be retained + * between successive calls to the filter unless they have been + * "set aside" with a call apr_bucket_setaside. Typically this will + * be done with ap_save_brigade(). Buckets removed from the brigade + * become the responsibility of the filter, which must arrange for + * them to be deleted, either by doing so directly or by inserting + * them in a brigade which will subsequently be destroyed. + * + * For the input and output filters, the return value of a filter should be + * an APR status value. For the init function, the return value should + * be an HTTP error code or OK if it was successful. + * + * @ingroup filter + * @{ + */ +typedef apr_status_t (*ap_out_filter_func)(ap_filter_t *f, + apr_bucket_brigade *b); +typedef apr_status_t (*ap_in_filter_func)(ap_filter_t *f, + apr_bucket_brigade *b, + ap_input_mode_t mode, + apr_read_type_e block, + apr_off_t readbytes); +typedef int (*ap_init_filter_func)(ap_filter_t *f); + +typedef union ap_filter_func { + ap_out_filter_func out_func; + ap_in_filter_func in_func; +} ap_filter_func; + +/** @} */ + +/** + * Filters have different types/classifications. These are used to group + * and sort the filters to properly sequence their operation. + * + * The types have a particular sort order, which allows us to insert them + * into the filter chain in a determistic order. Within a particular grouping, + * the ordering is equivalent to the order of calls to ap_add_*_filter(). + */ +typedef enum { + /** These filters are used to alter the content that is passed through + * them. Examples are SSI or PHP. */ + AP_FTYPE_RESOURCE = 10, + /** These filters are used to alter the content as a whole, but after all + * AP_FTYPE_RESOURCE filters are executed. These filters should not + * change the content-type. An example is deflate. */ + AP_FTYPE_CONTENT_SET = 20, + /** These filters are used to handle the protocol between server and + * client. Examples are HTTP and POP. */ + AP_FTYPE_PROTOCOL = 30, + /** These filters implement transport encodings (e.g., chunking). */ + AP_FTYPE_TRANSCODE = 40, + /** These filters will alter the content, but in ways that are + * more strongly associated with the connection. Examples are + * splitting an HTTP connection into multiple requests and + * buffering HTTP responses across multiple requests. + * + * It is important to note that these types of filters are not + * allowed in a sub-request. A sub-request's output can certainly + * be filtered by ::AP_FTYPE_RESOURCE filters, but all of the "final + * processing" is determined by the main request. */ + AP_FTYPE_CONNECTION = 50, + /** These filters don't alter the content. They are responsible for + * sending/receiving data to/from the client. */ + AP_FTYPE_NETWORK = 60 +} ap_filter_type; + +/** + * This is the request-time context structure for an installed filter (in + * the output filter chain). It provides the callback to use for filtering, + * the request this filter is associated with (which is important when + * an output chain also includes sub-request filters), the context for this + * installed filter, and the filter ordering/chaining fields. + * + * Filter callbacks are free to use ->ctx as they please, to store context + * during the filter process. Generally, this is superior over associating + * the state directly with the request. A callback should not change any of + * the other fields. + */ + +typedef struct ap_filter_rec_t ap_filter_rec_t; +typedef struct ap_filter_provider_t ap_filter_provider_t; + +/** + * @brief This structure is used for recording information about the + * registered filters. It associates a name with the filter's callback + * and filter type. + * + * At the moment, these are simply linked in a chain, so a ->next pointer + * is available. + * + * It is used for any filter that can be inserted in the filter chain. + * This may be either a httpd-2.0 filter or a mod_filter harness. + * In the latter case it contains dispatch, provider and protocol information. + * In the former case, the new fields (from dispatch) are ignored. + */ +struct ap_filter_rec_t { + /** The registered name for this filter */ + const char *name; + + /** The function to call when this filter is invoked. */ + ap_filter_func filter_func; + + /** The function to call directly before the handlers are invoked + * for a request. The init function is called once directly + * before running the handlers for a request or subrequest. The + * init function is never called for a connection filter (with + * ftype >= AP_FTYPE_CONNECTION). Any use of this function for + * filters for protocols other than HTTP is specified by the + * module supported that protocol. + */ + ap_init_filter_func filter_init_func; + + /** The next filter_rec in the list */ + struct ap_filter_rec_t *next; + + /** Providers for this filter */ + ap_filter_provider_t *providers; + + /** The type of filter, either AP_FTYPE_CONTENT or AP_FTYPE_CONNECTION. + * An AP_FTYPE_CONTENT filter modifies the data based on information + * found in the content. An AP_FTYPE_CONNECTION filter modifies the + * data based on the type of connection. + */ + ap_filter_type ftype; + + /** Trace level for this filter */ + int debug; + + /** Protocol flags for this filter */ + unsigned int proto_flags; +}; + +/** + * @brief The representation of a filter chain. + * + * Each request has a list + * of these structures which are called in turn to filter the data. Sub + * requests get an exact copy of the main requests filter chain. + */ +struct ap_filter_t { + /** The internal representation of this filter. This includes + * the filter's name, type, and the actual function pointer. + */ + ap_filter_rec_t *frec; + + /** A place to store any data associated with the current filter */ + void *ctx; + + /** The next filter in the chain */ + ap_filter_t *next; + + /** The request_rec associated with the current filter. If a sub-request + * adds filters, then the sub-request is the request associated with the + * filter. + */ + request_rec *r; + + /** The conn_rec associated with the current filter. This is analogous + * to the request_rec, except that it is used for connection filters. + */ + conn_rec *c; +}; + +/** + * Get the current bucket brigade from the next filter on the filter + * stack. The filter returns an apr_status_t value. If the bottom-most + * filter doesn't read from the network, then ::AP_NOBODY_READ is returned. + * The bucket brigade will be empty when there is nothing left to get. + * @param filter The next filter in the chain + * @param bucket The current bucket brigade. The original brigade passed + * to ap_get_brigade() must be empty. + * @param mode The way in which the data should be read + * @param block How the operations should be performed + * ::APR_BLOCK_READ, ::APR_NONBLOCK_READ + * @param readbytes How many bytes to read from the next filter. + */ +AP_DECLARE(apr_status_t) ap_get_brigade(ap_filter_t *filter, + apr_bucket_brigade *bucket, + ap_input_mode_t mode, + apr_read_type_e block, + apr_off_t readbytes); + +/** + * Pass the current bucket brigade down to the next filter on the filter + * stack. The filter returns an apr_status_t value. If the bottom-most + * filter doesn't write to the network, then ::AP_NOBODY_WROTE is returned. + * @param filter The next filter in the chain + * @param bucket The current bucket brigade + * + * @remark Ownership of the brigade is retained by the caller. On return, + * the contents of the brigade are UNDEFINED, and the caller must + * either call apr_brigade_cleanup or apr_brigade_destroy on + * the brigade. + */ +AP_DECLARE(apr_status_t) ap_pass_brigade(ap_filter_t *filter, + apr_bucket_brigade *bucket); + +/** + * Pass the current bucket brigade down to the next filter on the filter + * stack checking for filter errors. The filter returns an apr_status_t value. + * Returns ::OK if the brigade is successfully passed + * ::AP_FILTER_ERROR on a filter error + * ::HTTP_INTERNAL_SERVER_ERROR on all other errors + * @param r The request rec + * @param bucket The current bucket brigade + * @param fmt The format string. If NULL defaults to "ap_pass_brigade returned" + * @param ... The arguments to use to fill out the format string + * @remark Ownership of the brigade is retained by the caller. On return, + * the contents of the brigade are UNDEFINED, and the caller must + * either call apr_brigade_cleanup or apr_brigade_destroy on + * the brigade. + */ +AP_DECLARE(apr_status_t) ap_pass_brigade_fchk(request_rec *r, + apr_bucket_brigade *bucket, + const char *fmt, + ...) + __attribute__((format(printf,3,4))); + +/** + * This function is used to register an input filter with the system. + * After this registration is performed, then a filter may be added + * into the filter chain by using ap_add_input_filter() and simply + * specifying the name. + * + * @param name The name to attach to the filter function + * @param filter_func The filter function to name + * @param filter_init The function to call before the filter handlers + are invoked + * @param ftype The type of filter function, either ::AP_FTYPE_CONTENT_SET or + * ::AP_FTYPE_CONNECTION + * @see add_input_filter() + */ +AP_DECLARE(ap_filter_rec_t *) ap_register_input_filter(const char *name, + ap_in_filter_func filter_func, + ap_init_filter_func filter_init, + ap_filter_type ftype); + +/** @deprecated @see ap_register_output_filter_protocol */ +AP_DECLARE(ap_filter_rec_t *) ap_register_output_filter(const char *name, + ap_out_filter_func filter_func, + ap_init_filter_func filter_init, + ap_filter_type ftype); + +/* For httpd-?.? I suggest replacing the above with +#define ap_register_output_filter(name,ffunc,init,ftype) \ + ap_register_output_filter_protocol(name,ffunc,init,ftype,0) +*/ + +/** + * This function is used to register an output filter with the system. + * After this registration is performed, then a filter may be added + * directly to the filter chain by using ap_add_output_filter() and + * simply specifying the name, or as a provider under mod_filter. + * + * @param name The name to attach to the filter function + * @param filter_func The filter function to name + * @param filter_init The function to call before the filter handlers + * are invoked + * @param ftype The type of filter function, either ::AP_FTYPE_CONTENT_SET or + * ::AP_FTYPE_CONNECTION + * @param proto_flags Protocol flags: logical OR of AP_FILTER_PROTO_* bits + * @return the filter rec + * @see ap_add_output_filter() + */ +AP_DECLARE(ap_filter_rec_t *) ap_register_output_filter_protocol( + const char *name, + ap_out_filter_func filter_func, + ap_init_filter_func filter_init, + ap_filter_type ftype, + unsigned int proto_flags); + +/** + * Adds a named filter into the filter chain on the specified request record. + * The filter will be installed with the specified context pointer. + * + * Filters added in this way will always be placed at the end of the filters + * that have the same type (thus, the filters have the same order as the + * calls to ap_add_filter). If the current filter chain contains filters + * from another request, then this filter will be added before those other + * filters. + * + * To re-iterate that last comment. This function is building a FIFO + * list of filters. Take note of that when adding your filter to the chain. + * + * @param name The name of the filter to add + * @param ctx Context data to provide to the filter + * @param r The request to add this filter for (or NULL if it isn't associated with a request) + * @param c The connection to add the fillter for + */ +AP_DECLARE(ap_filter_t *) ap_add_input_filter(const char *name, void *ctx, + request_rec *r, conn_rec *c); + +/** + * Variant of ap_add_input_filter() that accepts a registered filter handle + * (as returned by ap_register_input_filter()) rather than a filter name + * + * @param f The filter handle to add + * @param ctx Context data to provide to the filter + * @param r The request to add this filter for (or NULL if it isn't associated with a request) + * @param c The connection to add the fillter for + */ +AP_DECLARE(ap_filter_t *) ap_add_input_filter_handle(ap_filter_rec_t *f, + void *ctx, + request_rec *r, + conn_rec *c); + +/** + * Returns the filter handle for use with ap_add_input_filter_handle. + * + * @param name The filter name to look up + */ +AP_DECLARE(ap_filter_rec_t *) ap_get_input_filter_handle(const char *name); + +/** + * Add a filter to the current request. Filters are added in a FIFO manner. + * The first filter added will be the first filter called. + * @param name The name of the filter to add + * @param ctx Context data to set in the filter + * @param r The request to add this filter for (or NULL if it isn't associated with a request) + * @param c The connection to add this filter for + * @note If adding a connection-level output filter (i.e. where the type + * is >= AP_FTYPE_CONNECTION) during processing of a request, the request + * object r must be passed in to ensure the filter chains are modified + * correctly. f->r will still be initialized as NULL in the new filter. + */ +AP_DECLARE(ap_filter_t *) ap_add_output_filter(const char *name, void *ctx, + request_rec *r, conn_rec *c); + +/** + * Variant of ap_add_output_filter() that accepts a registered filter handle + * (as returned by ap_register_output_filter()) rather than a filter name + * + * @param f The filter handle to add + * @param ctx Context data to set in the filter + * @param r The request to add this filter for (or NULL if it isn't associated with a request) + * @param c The connection to add the filter for + * @note If adding a connection-level output filter (i.e. where the type + * is >= AP_FTYPE_CONNECTION) during processing of a request, the request + * object r must be passed in to ensure the filter chains are modified + * correctly. f->r will still be initialized as NULL in the new filter. + */ +AP_DECLARE(ap_filter_t *) ap_add_output_filter_handle(ap_filter_rec_t *f, + void *ctx, + request_rec *r, + conn_rec *c); + +/** + * Returns the filter handle for use with ap_add_output_filter_handle. + * + * @param name The filter name to look up + */ +AP_DECLARE(ap_filter_rec_t *) ap_get_output_filter_handle(const char *name); + +/** + * Remove an input filter from either the request or connection stack + * it is associated with. + * @param f The filter to remove + */ + +AP_DECLARE(void) ap_remove_input_filter(ap_filter_t *f); + +/** + * Remove an output filter from either the request or connection stack + * it is associated with. + * @param f The filter to remove + */ + +AP_DECLARE(void) ap_remove_output_filter(ap_filter_t *f); + +/** + * Remove an input filter from either the request or connection stack + * it is associated with. + * @param next The filter stack to search + * @param handle The filter handle (name) to remove + * @return APR_SUCCESS on removal or error + */ +AP_DECLARE(apr_status_t) ap_remove_input_filter_byhandle(ap_filter_t *next, + const char *handle); +/** + * Remove an output filter from either the request or connection stack + * it is associated with. + * @param next The filter stack to search + * @param handle The filter handle (name) to remove + * @return APR_SUCCESS on removal or error + */ +AP_DECLARE(apr_status_t) ap_remove_output_filter_byhandle(ap_filter_t *next, + const char *handle); + +/* The next two filters are for abstraction purposes only. They could be + * done away with, but that would require that we break modules if we ever + * want to change our filter registration method. The basic idea, is that + * all filters have a place to store data, the ctx pointer. These functions + * fill out that pointer with a bucket brigade, and retrieve that data on + * the next call. The nice thing about these functions, is that they + * automatically concatenate the bucket brigades together for you. This means + * that if you have already stored a brigade in the filters ctx pointer, then + * when you add more it will be tacked onto the end of that brigade. When + * you retrieve data, if you pass in a bucket brigade to the get function, + * it will append the current brigade onto the one that you are retrieving. + */ + +/** + * prepare a bucket brigade to be setaside. If a different brigade was + * set-aside earlier, then the two brigades are concatenated together. + * @param f The current filter + * @param save_to The brigade that was previously set-aside. Regardless, the + * new bucket brigade is returned in this location. + * @param b The bucket brigade to save aside. This brigade is always empty + * on return + * @param p Ensure that all data in the brigade lives as long as this pool + */ +AP_DECLARE(apr_status_t) ap_save_brigade(ap_filter_t *f, + apr_bucket_brigade **save_to, + apr_bucket_brigade **b, apr_pool_t *p); + +/** + * Flush function for apr_brigade_* calls. This calls ap_pass_brigade + * to flush the brigade if the brigade buffer overflows. + * @param bb The brigade to flush + * @param ctx The filter to pass the brigade to + * @note this function has nothing to do with FLUSH buckets. It is simply + * a way to flush content out of a brigade and down a filter stack. + */ +AP_DECLARE_NONSTD(apr_status_t) ap_filter_flush(apr_bucket_brigade *bb, + void *ctx); + +/** + * Flush the current brigade down the filter stack. + * @param f The filter we are passing to + * @param bb The brigade to flush + */ +AP_DECLARE(apr_status_t) ap_fflush(ap_filter_t *f, apr_bucket_brigade *bb); + +/** + * Write a buffer for the current filter, buffering if possible. + * @param f the filter we are writing to + * @param bb The brigade to buffer into + * @param data The data to write + * @param nbyte The number of bytes in the data + */ +#define ap_fwrite(f, bb, data, nbyte) \ + apr_brigade_write(bb, ap_filter_flush, f, data, nbyte) + +/** + * Write a buffer for the current filter, buffering if possible. + * @param f the filter we are writing to + * @param bb The brigade to buffer into + * @param str The string to write + */ +#define ap_fputs(f, bb, str) \ + apr_brigade_write(bb, ap_filter_flush, f, str, strlen(str)) + +/** + * Write a character for the current filter, buffering if possible. + * @param f the filter we are writing to + * @param bb The brigade to buffer into + * @param c The character to write + */ +#define ap_fputc(f, bb, c) \ + apr_brigade_putc(bb, ap_filter_flush, f, c) + +/** + * Write an unspecified number of strings to the current filter + * @param f the filter we are writing to + * @param bb The brigade to buffer into + * @param ... The strings to write + */ +AP_DECLARE_NONSTD(apr_status_t) ap_fputstrs(ap_filter_t *f, + apr_bucket_brigade *bb, + ...) + AP_FN_ATTR_SENTINEL; + +/** + * Output data to the filter in printf format + * @param f the filter we are writing to + * @param bb The brigade to buffer into + * @param fmt The format string + * @param ... The arguments to use to fill out the format string + */ +AP_DECLARE_NONSTD(apr_status_t) ap_fprintf(ap_filter_t *f, + apr_bucket_brigade *bb, + const char *fmt, + ...) + __attribute__((format(printf,3,4))); + +/** + * set protocol requirements for an output content filter + * (only works with AP_FTYPE_RESOURCE and AP_FTYPE_CONTENT_SET) + * @param f the filter in question + * @param proto_flags Logical OR of AP_FILTER_PROTO_* bits + */ +AP_DECLARE(void) ap_filter_protocol(ap_filter_t* f, unsigned int proto_flags); + +/** Filter changes contents (so invalidating checksums/etc) */ +#define AP_FILTER_PROTO_CHANGE 0x1 + +/** Filter changes length of contents (so invalidating content-length/etc) */ +#define AP_FILTER_PROTO_CHANGE_LENGTH 0x2 + +/** Filter requires complete input and can't work on byteranges */ +#define AP_FILTER_PROTO_NO_BYTERANGE 0x4 + +/** Filter should not run in a proxy */ +#define AP_FILTER_PROTO_NO_PROXY 0x8 + +/** Filter makes output non-cacheable */ +#define AP_FILTER_PROTO_NO_CACHE 0x10 + +/** Filter is incompatible with "Cache-Control: no-transform" */ +#define AP_FILTER_PROTO_TRANSFORM 0x20 + +/** + * @} + */ + +#ifdef __cplusplus +} +#endif + +#endif /* !AP_FILTER_H */ |