text: /* 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  http_protocol.h
   * @brief HTTP protocol handling
   *
   * @defgroup APACHE_CORE_PROTO HTTP Protocol Handling
   * @ingroup  APACHE_CORE
   * @{
   */
  
  #ifndef APACHE_HTTP_PROTOCOL_H
  #define APACHE_HTTP_PROTOCOL_H
  
  #include "httpd.h"
  #include "apr_hooks.h"
  #include "apr_portable.h"
  #include "apr_mmap.h"
  #include "apr_buckets.h"
  #include "util_filter.h"
  
  #ifdef __cplusplus
  extern "C" {
  #endif
  
  /**
   * This hook allows modules to insert filters for the current error response
   * @param r the current request
   * @ingroup hooks
   */
  AP_DECLARE_HOOK(void,insert_error_filter,(request_rec *r))
  
  /** This is an optimization.  We keep a record of the filter_rec that
   * stores the old_write filter, so that we can avoid strcmp's later.
   */
  AP_DECLARE_DATA extern ap_filter_rec_t *ap_old_write_func;
  
  /*
   * Prototypes for routines which either talk directly back to the user,
   * or control the ones that eventually do.
   */
  
  /**
   * Read a request and fill in the fields.
   * @param c The current connection
   * @return The new request_rec
   */ 
  request_rec *ap_read_request(conn_rec *c);
  
  /**
   * Read the mime-encoded headers.
   * @param r The current request
   */
  AP_DECLARE(void) ap_get_mime_headers(request_rec *r);
  
  /**
   * Optimized version of ap_get_mime_headers() that requires a
   * temporary brigade to work with
   * @param r The current request
   * @param bb temp brigade
   */
  AP_DECLARE(void) ap_get_mime_headers_core(request_rec *r,
                                            apr_bucket_brigade *bb);
  
  /* Finish up stuff after a request */
  
  /**
   * Called at completion of sending the response.  It sends the terminating
   * protocol information.
   * @param r The current request
   */
  AP_DECLARE(void) ap_finalize_request_protocol(request_rec *r);
  
  /**
   * Send error back to client.
   * @param r The current request
   * @param recursive_error last arg indicates error status in case we get 
   *      an error in the process of trying to deal with an ErrorDocument 
   *      to handle some other error.  In that case, we print the default 
   *      report for the first thing that went wrong, and more briefly report 
   *      on the problem with the ErrorDocument.
   */
  AP_DECLARE(void) ap_send_error_response(request_rec *r, int recursive_error);
  
  /* Set last modified header line from the lastmod date of the associated file.
   * Also, set content length.
   *
   * May return an error status, typically HTTP_NOT_MODIFIED (that when the
   * permit_cache argument is set to one).
   */
  
  /**
   * Set the content length for this request
   * @param r The current request
   * @param length The new content length
   */
  AP_DECLARE(void) ap_set_content_length(request_rec *r, apr_off_t length);
  
  /**
   * Set the keepalive status for this request
   * @param r The current request
   * @return 1 if keepalive can be set, 0 otherwise
   */
  AP_DECLARE(int) ap_set_keepalive(request_rec *r);
  
  /**
   * Return the latest rational time from a request/mtime pair.  Mtime is 
   * returned unless it's in the future, in which case we return the current time.
   * @param r The current request
   * @param mtime The last modified time
   * @return the latest rational time.
   */
  AP_DECLARE(apr_time_t) ap_rationalize_mtime(request_rec *r, apr_time_t mtime);
  
  /**
   * Build the content-type that should be sent to the client from the
   * content-type specified.  The following rules are followed:
   *    - if type is NULL, type is set to ap_default_type(r)
   *    - if charset adding is disabled, stop processing and return type.
   *    - then, if there are no parameters on type, add the default charset
   *    - return type
   * @param r The current request
   * @param type The content type
   * @return The content-type
   */ 
  AP_DECLARE(const char *) ap_make_content_type(request_rec *r,
                                                const char *type);
  
  #ifdef CORE_PRIVATE
  /**
   * Precompile metadata structures used by ap_make_content_type()
   * @param pool The pool to use for allocations
   */
  AP_DECLARE(void) ap_setup_make_content_type(apr_pool_t *pool);
  #endif /* CORE_PRIVATE */
  
  /**
   * Construct an entity tag from the resource information.  If it's a real
   * file, build in some of the file characteristics.
   * @param r The current request
   * @param force_weak Force the entity tag to be weak - it could be modified
   *                   again in as short an interval.
   * @return The entity tag
   */ 
  AP_DECLARE(char *) ap_make_etag(request_rec *r, int force_weak);
  
  /**
   * Set the E-tag outgoing header
   * @param r The current request
   */
  AP_DECLARE(void) ap_set_etag(request_rec *r);
  
  /**
   * Set the last modified time for the file being sent
   * @param r The current request
   */
  AP_DECLARE(void) ap_set_last_modified(request_rec *r);
  
  /**
   * Implements condition GET rules for HTTP/1.1 specification.  This function
   * inspects the client headers and determines if the response fulfills 
   * the requirements specified.
   * @param r The current request
   * @return OK if the response fulfills the condition GET rules, some
   *         other status code otherwise
   */
  AP_DECLARE(int) ap_meets_conditions(request_rec *r);
  
  /* Other ways to send stuff at the client.  All of these keep track
   * of bytes_sent automatically.  This indirection is intended to make
   * it a little more painless to slide things like HTTP-NG packetization
   * underneath the main body of the code later.  In the meantime, it lets
   * us centralize a bit of accounting (bytes_sent).
   *
   * These also return the number of bytes written by the call.
   * They should only be called with a timeout registered, for obvious reaasons.
   * (Ditto the send_header stuff).
   */
  
  /**
   * Send an entire file to the client, using sendfile if supported by the 
   * current platform
   * @param fd The file to send.
   * @param r The current request
   * @param offset Offset into the file to start sending.
   * @param length Amount of data to send
   * @param nbytes Amount of data actually sent
   */
  AP_DECLARE(apr_status_t) ap_send_fd(apr_file_t *fd, request_rec *r, apr_off_t offset, 
                                     apr_size_t length, apr_size_t *nbytes);
  
  #if APR_HAS_MMAP
  /**
   * Send an MMAP'ed file to the client
   * @param mm The MMAP'ed file to send
   * @param r The current request
   * @param offset The offset into the MMAP to start sending
   * @param length The amount of data to send
   * @return The number of bytes sent
   */
  AP_DECLARE(size_t) ap_send_mmap(apr_mmap_t *mm, request_rec *r, size_t offset,
                               size_t length);
  #endif
  
  
  /**
   * Register a new request method, and return the offset that will be
   * associated with that method.
   *
   * @param p        The pool to create registered method numbers from.
   * @param methname The name of the new method to register.
   * @return         Ab int value representing an offset into a bitmask.
   */
  AP_DECLARE(int) ap_method_register(apr_pool_t *p, const char *methname);
  
  /**
   * Initialize the method_registry and allocate memory for it.
   *
   * @param p Pool to allocate memory for the registry from.
   */
  AP_DECLARE(void) ap_method_registry_init(apr_pool_t *p);
  
  /**
   * This is a convenience macro to ease with checking a mask
   * against a method name.
   */
  #define AP_METHOD_CHECK_ALLOWED(mask, methname) \
      ((mask) & (AP_METHOD_BIT << ap_method_number_of((methname))))
  
  /**
   * Create a new method list with the specified number of preallocated
   * slots for extension methods.
   *
   * @param   p       Pointer to a pool in which the structure should be
   *                  allocated.
   * @param   nelts   Number of preallocated extension slots
   * @return  Pointer to the newly created structure.
   */
  AP_DECLARE(ap_method_list_t *) ap_make_method_list(apr_pool_t *p, int nelts);
  
  
  /**
   * Copy a method list
   *
   * @param   dest List to copy to
   * @param   src  List to copy from
   */
  AP_DECLARE(void) ap_copy_method_list(ap_method_list_t *dest,
  				     ap_method_list_t *src);
  
  /**
   * Search for an HTTP method name in an ap_method_list_t structure, and
   * return true if found.
   *
   * @param   method  String containing the name of the method to check.
   * @param   l       Pointer to a method list, such as cmd->methods_limited.
   * @return  1 if method is in the list, otherwise 0
   */
  AP_DECLARE(int) ap_method_in_list(ap_method_list_t *l, const char *method);
  
  /**
   * Add an HTTP method name to an ap_method_list_t structure if it isn't
   * already listed.
   *
   * @param   method  String containing the name of the method to check.
   * @param   l       Pointer to a method list, such as cmd->methods_limited.
   * @return  None.
   */
  AP_DECLARE(void) ap_method_list_add(ap_method_list_t *l, const char *method);
      
  /**
   * Remove an HTTP method name from an ap_method_list_t structure.
   *
   * @param   l       Pointer to a method list, such as cmd->methods_limited.
   * @param   method  String containing the name of the method to remove.
   * @return  None.
   */
  AP_DECLARE(void) ap_method_list_remove(ap_method_list_t *l,
  				       const char *method);
  
  /**
   * Reset a method list to be completely empty.
   *
   * @param   l       Pointer to a method list, such as cmd->methods_limited.
   * @return  None.
   */
  AP_DECLARE(void) ap_clear_method_list(ap_method_list_t *l);
      
  /**
   * Set the content type for this request (r->content_type). 
   * @param r The current request
   * @param ct The new content type
   * @warning This function must be called to set r->content_type in order 
   * for the AddOutputFilterByType directive to work correctly.
   */
  AP_DECLARE(void) ap_set_content_type(request_rec *r, const char *ct);
  
  /**
   * Set the Accept-Ranges header for this response
   * @param r The current request
   */
  AP_DECLARE(void) ap_set_accept_ranges(request_rec *r);
  
  
  /* Hmmm... could macrofy these for now, and maybe forever, though the
   * definitions of the macros would get a whole lot hairier.
   */
  
  /**
   * Output one character for this request
   * @param c the character to output
   * @param r the current request
   * @return The number of bytes sent
   */
  AP_DECLARE(int) ap_rputc(int c, request_rec *r);
  
  /**
   * Output a string for the current request
   * @param str The string to output
   * @param r The current request
   * @return The number of bytes sent
   */
  AP_DECLARE(int) ap_rputs(const char *str, request_rec *r);
  
  /**
   * Write a buffer for the current request
   * @param buf The buffer to write
   * @param nbyte The number of bytes to send from the buffer
   * @param r The current request
   * @return The number of bytes sent
   */
  AP_DECLARE(int) ap_rwrite(const void *buf, int nbyte, request_rec *r);
  
  /**
   * Write an unspecified number of strings to the request
   * @param r The current request
   * @param ... The strings to write
   * @return The number of bytes sent
   */
  AP_DECLARE_NONSTD(int) ap_rvputs(request_rec *r,...);
  
  /**
   * Output data to the client in a printf format
   * @param r The current request
   * @param fmt The format string
   * @param vlist The arguments to use to fill out the format string
   * @return The number of bytes sent
   */
  AP_DECLARE(int) ap_vrprintf(request_rec *r, const char *fmt, va_list vlist);
  
  /**
   * Output data to the client in a printf format
   * @param r The current request
   * @param fmt The format string
   * @param ... The arguments to use to fill out the format string
   * @return The number of bytes sent
   */
  AP_DECLARE_NONSTD(int) ap_rprintf(request_rec *r, const char *fmt,...)
  				__attribute__((format(printf,2,3)));
  
  /**
   * Flush all of the data for the current request to the client
   * @param r The current request
   * @return The number of bytes sent
   */
  AP_DECLARE(int) ap_rflush(request_rec *r);
  
  /**
   * Index used in custom_responses array for a specific error code
   * (only use outside protocol.c is in getting them configured).
   * @param status HTTP status code
   * @return The index of the response
   */
  AP_DECLARE(int) ap_index_of_response(int status);
  
  /** 
   * Return the Status-Line for a given status code (excluding the
   * HTTP-Version field). If an invalid or unknown status code is
   * passed, "500 Internal Server Error" will be returned. 
   * @param status The HTTP status code
   * @return The Status-Line
   */
  AP_DECLARE(const char *) ap_get_status_line(int status);
  
  /* Reading a block of data from the client connection (e.g., POST arg) */
  
  /**
   * Setup the client to allow Apache to read the request body.
   * @param r The current request
   * @param read_policy How the server should interpret a chunked 
   *                    transfer-encoding.  One of: <pre>
   *    REQUEST_NO_BODY          Send 413 error if message has any body
   *    REQUEST_CHUNKED_ERROR    Send 411 error if body without Content-Length
   *    REQUEST_CHUNKED_DECHUNK  If chunked, remove the chunks for me.
   * </pre>
   * @return either OK or an error code
   */
  AP_DECLARE(int) ap_setup_client_block(request_rec *r, int read_policy);
  
  /**
   * Determine if the client has sent any data.  This also sends a 
   * 100 Continue response to HTTP/1.1 clients, so modules should not be called
   * until the module is ready to read content.
   * @warning Never call this function more than once.
   * @param r The current request
   * @return 0 if there is no message to read, 1 otherwise
   */
  AP_DECLARE(int) ap_should_client_block(request_rec *r);
  
  /**
   * Call this in a loop.  It will put data into a buffer and return the length
   * of the input block
   * @param r The current request
   * @param buffer The buffer in which to store the data
   * @param bufsiz The size of the buffer
   * @return Number of bytes inserted into the buffer.  When done reading, 0
   *         if EOF, or -1 if there was an error
   */
  AP_DECLARE(long) ap_get_client_block(request_rec *r, char *buffer, apr_size_t bufsiz);
  
  /**
   * In HTTP/1.1, any method can have a body.  However, most GET handlers
   * wouldn't know what to do with a request body if they received one.
   * This helper routine tests for and reads any message body in the request,
   * simply discarding whatever it receives.  We need to do this because
   * failing to read the request body would cause it to be interpreted
   * as the next request on a persistent connection.
   * @param r The current request
   * @return error status if request is malformed, OK otherwise 
   */
  AP_DECLARE(int) ap_discard_request_body(request_rec *r);
  
  /**
   * Setup the output headers so that the client knows how to authenticate
   * itself the next time, if an authentication request failed.  This function
   * works for both basic and digest authentication
   * @param r The current request
   */ 
  AP_DECLARE(void) ap_note_auth_failure(request_rec *r);
  
  /**
   * Setup the output headers so that the client knows how to authenticate
   * itself the next time, if an authentication request failed.  This function
   * works only for basic authentication
   * @param r The current request
   */ 
  AP_DECLARE(void) ap_note_basic_auth_failure(request_rec *r);
  
  /**
   * Setup the output headers so that the client knows how to authenticate
   * itself the next time, if an authentication request failed.  This function
   * works only for digest authentication
   * @param r The current request
   */ 
  AP_DECLARE(void) ap_note_digest_auth_failure(request_rec *r);
  
  /**
   * Get the password from the request headers
   * @param r The current request
   * @param pw The password as set in the headers
   * @return 0 (OK) if it set the 'pw' argument (and assured
   *         a correct value in r->user); otherwise it returns 
   *         an error code, either HTTP_INTERNAL_SERVER_ERROR if things are 
   *         really confused, HTTP_UNAUTHORIZED if no authentication at all 
   *         seemed to be in use, or DECLINED if there was authentication but 
   *         it wasn't Basic (in which case, the caller should presumably 
   *         decline as well).
   */
  AP_DECLARE(int) ap_get_basic_auth_pw(request_rec *r, const char **pw);
  
  /**
   * parse_uri: break apart the uri
   * @warning Side Effects: 
   *    @li sets r->args to rest after '?' (or NULL if no '?')
   *    @li sets r->uri to request uri (without r->args part)
   *    @li sets r->hostname (if not set already) from request (scheme://host:port)
   * @param r The current request
   * @param uri The uri to break apart
   */
  AP_CORE_DECLARE(void) ap_parse_uri(request_rec *r, const char *uri);
  
  /**
   * Get the next line of input for the request
   * @param s The buffer into which to read the line
   * @param n The size of the buffer
   * @param r The request
   * @param fold Whether to merge continuation lines
   * @return The length of the line, if successful
   *         n, if the line is too big to fit in the buffer
   *         -1 for miscellaneous errors
   */
  AP_DECLARE(int) ap_getline(char *s, int n, request_rec *r, int fold);
  
  /**
   * Get the next line of input for the request
   *
   * Note: on ASCII boxes, ap_rgetline is a macro which simply calls 
   *       ap_rgetline_core to get the line of input.
   * 
   *       on EBCDIC boxes, ap_rgetline is a wrapper function which
   *       translates ASCII protocol lines to the local EBCDIC code page
   *       after getting the line of input.
   *       
   * @param s Pointer to the pointer to the buffer into which the line
   *          should be read; if *s==NULL, a buffer of the necessary size
   *          to hold the data will be allocated from the request pool
   * @param n The size of the buffer
   * @param read The length of the line.
   * @param r The request
   * @param fold Whether to merge continuation lines
   * @param bb Working brigade to use when reading buckets
   * @return APR_SUCCESS, if successful
   *         APR_ENOSPC, if the line is too big to fit in the buffer
   *         Other errors where appropriate
   */
  #if APR_CHARSET_EBCDIC
  AP_DECLARE(apr_status_t) ap_rgetline(char **s, apr_size_t n, 
                                       apr_size_t *read,
                                       request_rec *r, int fold,
                                       apr_bucket_brigade *bb);
  #else /* ASCII box */
  #define ap_rgetline(s, n, read, r, fold, bb) \
          ap_rgetline_core((s), (n), (read), (r), (fold), (bb))
  #endif
  
  /** @see ap_rgetline */
  AP_DECLARE(apr_status_t) ap_rgetline_core(char **s, apr_size_t n, 
                                            apr_size_t *read,
                                            request_rec *r, int fold,
                                            apr_bucket_brigade *bb);
  
  /**
   * Get the method number associated with the given string, assumed to
   * contain an HTTP method.  Returns M_INVALID if not recognized.
   * @param method A string containing a valid HTTP method
   * @return The method number
   */
  AP_DECLARE(int) ap_method_number_of(const char *method);
  
  /**
   * Get the method name associated with the given internal method
   * number.  Returns NULL if not recognized.
   * @param p A pool to use for temporary allocations.
   * @param methnum An integer value corresponding to an internal method number
   * @return The name corresponding to the method number
   */
  AP_DECLARE(const char *) ap_method_name_of(apr_pool_t *p, int methnum);
  
  
    /* Hooks */
    /*
     * post_read_request --- run right after read_request or internal_redirect,
     *                  and not run during any subrequests.
     */
  /**
   * This hook allows modules to affect the request immediately after the request
   * has been read, and before any other phases have been processes.  This allows
   * modules to make decisions based upon the input header fields
   * @param r The current request
   * @return OK or DECLINED
   */
  AP_DECLARE_HOOK(int,post_read_request,(request_rec *r))
  
  /**
   * This hook allows modules to perform any module-specific logging activities
   * over and above the normal server things.
   * @param r The current request
   * @return OK, DECLINED, or HTTP_...
   */
  AP_DECLARE_HOOK(int,log_transaction,(request_rec *r))
  
  /**
   * This hook allows modules to retrieve the http scheme for a request.  This
   * allows Apache modules to easily extend the schemes that Apache understands
   * @param r The current request
   * @return The http scheme from the request
   */
  AP_DECLARE_HOOK(const char *,http_scheme,(const request_rec *r))
  
  /**
   * Return the default port from the current request
   * @param r The current request
   * @return The current port
   */
  AP_DECLARE_HOOK(apr_port_t,default_port,(const request_rec *r))
  
  /** @see ap_bucket_type_error */
  typedef struct ap_bucket_error ap_bucket_error;
  
  /**
   * @struct ap_bucket_error
   * @brief  A bucket referring to an HTTP error
   *
   * This bucket can be passed down the filter stack to indicate that an
   * HTTP error occurred while running a filter.  In order for this bucket
   * to be used successfully, it MUST be sent as the first bucket in the
   * first brigade to be sent from a given filter.
   */
  struct ap_bucket_error {
      /** Number of buckets using this memory */
      apr_bucket_refcount refcount;
      /** The error code */
      int status;
      /** The error string */
      const char    *data;
  };
  
  /** @see ap_bucket_type_error */
  AP_DECLARE_DATA extern const apr_bucket_type_t ap_bucket_type_error;
  
  /**
   * Determine if a bucket is an error bucket
   * @param e The bucket to inspect
   * @return true or false
   */
  #define AP_BUCKET_IS_ERROR(e)         (e->type == &ap_bucket_type_error)
  
  /**
   * Make the bucket passed in an error bucket
   * @param b The bucket to make into an error bucket
   * @param error The HTTP error code to put in the bucket. 
   * @param buf An optional error string to put in the bucket.
   * @param p A pool to allocate out of.
   * @return The new bucket, or NULL if allocation failed
   */
  AP_DECLARE(apr_bucket *) ap_bucket_error_make(apr_bucket *b, int error,
                  const char *buf, apr_pool_t *p);
  
  /**
   * Create a bucket referring to an HTTP error.
   * @param error The HTTP error code to put in the bucket. 
   * @param buf An optional error string to put in the bucket.
   * @param p A pool to allocate the error string out of.
   * @param list The bucket allocator from which to allocate the bucket
   * @return The new bucket, or NULL if allocation failed
   */
  AP_DECLARE(apr_bucket *) ap_bucket_error_create(int error, const char *buf,
                                                  apr_pool_t *p,
                                                  apr_bucket_alloc_t *list);
  
  AP_DECLARE_NONSTD(apr_status_t) ap_byterange_filter(ap_filter_t *f, apr_bucket_brigade *b);
  AP_DECLARE_NONSTD(apr_status_t) ap_http_header_filter(ap_filter_t *f, apr_bucket_brigade *b);
  AP_DECLARE_NONSTD(apr_status_t) ap_content_length_filter(ap_filter_t *,
                                                                apr_bucket_brigade *);
  AP_DECLARE_NONSTD(apr_status_t) ap_old_write_filter(ap_filter_t *f, apr_bucket_brigade *b);
  
  /**
   * Sett up the protocol fields for subsidiary requests
   * @param rnew New Sub Request
   * @param r current request
   */
  AP_DECLARE(void) ap_set_sub_req_protocol(request_rec *rnew, const request_rec *r);
  
  /**
   * A wrapup function to keep the internal accounting straight.
   * Indicates that there is no more content coming.
   * @param sub_r Subrequest that is now compete
   */
  AP_DECLARE(void) ap_finalize_sub_req_protocol(request_rec *sub_r);
  
  /**
   * Send an interim (HTTP 1xx) response immediately.
   * @param r The request
   * @param send_headers Whether to send&clear headers in r->headers_out
   */
  AP_DECLARE(void) ap_send_interim_response(request_rec *r, int send_headers);
                                                                                  
  #ifdef __cplusplus
  }
  #endif
  
  #endif	/* !APACHE_HTTP_PROTOCOL_H */
  /** @} */
  