/* 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_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 or "", return NULL (do not set content-type).

 *    - 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);

/**

 * 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);

/**

 * 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);

typedef enum {

    AP_CONDITION_NONE,

    AP_CONDITION_NOMATCH,

    AP_CONDITION_WEAK,

    AP_CONDITION_STRONG

} ap_condition_e;

/**

 * Tests conditional request rules for the If-Match header.

 * @param r The current request

 * @param headers The response headers to check against

 * @return AP_CONDITION_NONE if the header is missing, AP_CONDITION_NOMATCH

 *         if the header does not match, AP_CONDITION_STRONG for a strong

 *         match. Weak matches are not permitted for the If-Match header.

 */

AP_DECLARE(ap_condition_e) ap_condition_if_match(request_rec *r,

        apr_table_t *headers);

/**

 * Tests conditional request rules for the If-Unmodified-Since header.

 * @param r The current request

 * @param headers The response headers to check against

 * @return AP_CONDITION_NONE if the header is missing, AP_CONDITION_NOMATCH

 *         if the header does not match, AP_CONDITION_WEAK if a weak match

 *         was present and allowed by RFC2616, AP_CONDITION_STRONG for a

 *         strong match.

 */

AP_DECLARE(ap_condition_e) ap_condition_if_unmodified_since(request_rec *r,

        apr_table_t *headers);

/**

 * Tests conditional request rules for the If-None-Match header.

 * @param r The current request

 * @param headers The response headers to check against

 * @return AP_CONDITION_NONE if the header is missing, AP_CONDITION_NOMATCH

 *         if the header does not match, AP_CONDITION_WEAK if a weak match

 *         was present and allowed by RFC2616, AP_CONDITION_STRONG for a

 *         strong match.

 */

AP_DECLARE(ap_condition_e) ap_condition_if_none_match(request_rec *r,

        apr_table_t *headers);

/**

 * Tests conditional request rules for the If-Modified-Since header.

 * @param r The current request

 * @param headers The response headers to check against

 * @return AP_CONDITION_NONE if the header is missing, AP_CONDITION_NOMATCH

 *         if the header does not match, AP_CONDITION_WEAK if a weak match

 *         was present and allowed by RFC2616, AP_CONDITION_STRONG for a

 *         strong match.

 */

AP_DECLARE(ap_condition_e) ap_condition_if_modified_since(request_rec *r,

        apr_table_t *headers);

/**

 * Tests conditional request rules for the If-Range header.

 * @param r The current request

 * @param headers The response headers to check against

 * @return AP_CONDITION_NONE if either the If-Range or Range header is

 *         missing, AP_CONDITION_NOMATCH if the header does not match,

 *         AP_CONDITION_STRONG for a strong match. Weak matches are not

 *         permitted for the If-Range header.

 */

AP_DECLARE(ap_condition_e) ap_condition_if_range(request_rec *r,

        apr_table_t *headers);

/**

 * 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(apr_size_t) ap_send_mmap(apr_mmap_t *mm,

                                    request_rec *r,

                                    apr_size_t offset,

                                    apr_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         An 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 r->allowed_methods.

 * @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 r->allowed_methods.

 * @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 r->allowed_methods.

 * @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 r->allowed_methods.

 * @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);

/**

 * 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);

/**

 * Output a string for the current request

 * @param str The string to output

 * @param r The current request

 * @return The number of bytes sent

 * @note ap_rputs may be implemented as macro or inline function

 */

static APR_INLINE int ap_rputs(const char *str, request_rec *r)

{

    return ap_rwrite(str, (int)strlen(str), 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,...)

                       AP_FN_ATTR_SENTINEL;

/**

 * 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 0 on success, -1 if an error occurred

 */

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: 

 *    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.

 * 

 * @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);

/**

 * Map specific APR codes returned by the filter stack to HTTP error

 * codes, or the default status code provided. Use it as follows:

 *

 * return ap_map_http_request_error(rv, HTTP_BAD_REQUEST);

 *

 * If the filter has already handled the error, AP_FILTER_ERROR will

 * be returned, which is cleanly passed through.

 *

 * These mappings imply that the filter stack is reading from the

 * downstream client, the proxy will map these codes differently.

 * @param rv APR status code

 * @param status Default HTTP code should the APR code not be recognised

 * @return Mapped HTTP status code

 */

AP_DECLARE(int) ap_map_http_request_error(apr_status_t rv, int status);

/**

 * 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.

 * @param r The current request

 */

AP_DECLARE(void) ap_note_auth_failure(request_rec *r);

/**

 * @deprecated @see ap_note_auth_failure

 */

AP_DECLARE(void) ap_note_basic_auth_failure(request_rec *r);

/**

 * @deprecated @see ap_note_auth_failure

 */

AP_DECLARE(void) ap_note_digest_auth_failure(request_rec *r);

/**

 * This hook allows modules to add support for a specific auth type to

 * ap_note_auth_failure

 * @param r the current request

 * @param auth_type the configured auth_type

 * @return OK, DECLINED

 */

AP_DECLARE_HOOK(int, note_auth_failure, (request_rec *r, const char *auth_type))

/**

 * Get the password from the request headers. This function has multiple side

 * effects due to its prior use in the old authentication framework.

 * ap_get_basic_auth_components() should be preferred.

 *

 * @deprecated @see ap_get_basic_auth_components

 * @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);

#define AP_GET_BASIC_AUTH_PW_NOTE "AP_GET_BASIC_AUTH_PW_NOTE"

/**

 * Get the username and/or password from the request's Basic authentication

 * headers. Unlike ap_get_basic_auth_pw(), calling this function has no side

 * effects on the passed request_rec.

 *

 * @param r The current request

 * @param username If not NULL, set to the username sent by the client

 * @param password If not NULL, set to the password sent by the client

 * @return APR_SUCCESS if the credentials were successfully parsed and returned;

 *         APR_EINVAL if there was no authentication header sent or if the

 *         client was not using the Basic authentication scheme. username and

 *         password are unchanged on failure.

 */

AP_DECLARE(apr_status_t) ap_get_basic_auth_components(const request_rec *r,

                                                      const char **username,

                                                      const char **password);

/**

 * 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);

#define AP_GETLINE_FOLD 1 /* Whether to merge continuation lines */

#define AP_GETLINE_CRLF 2 /* Whether line ends must be in the form CR LF */

#define AP_GETLINE_NOSPC_EOL 4 /* Whether to consume up to and including the

                                  end of line on APR_ENOSPC */

/**

 * 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 flags Bit flag of multiple parsing options

 *              AP_GETLINE_FOLD Whether to merge continuation lines

 *              AP_GETLINE_CRLF Whether line ends must be in the form CR LF

 * @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 flags);

/**

 * 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 flags Bit flag of multiple parsing options

 *              AP_GETLINE_FOLD Whether to merge continuation lines

 *              AP_GETLINE_CRLF Whether line ends must be in the form CR LF

 * @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 flags,

                                     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 flags,

                                          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 */

/*

 * pre_read_request --- run right before read_request_line(),

 *                  and not run during any subrequests.

 */

/**

 * This hook allows modules to affect the request or connection immediately before

 * the request has been read, and before any other phases have been processes.

 * @param r The current request of the soon-to-be-read request

 * @param c The connection

 * @return None/void

 */

AP_DECLARE_HOOK(void,pre_read_request,(request_rec *r, conn_rec *c))

/*

 * 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))

#define AP_PROTOCOL_HTTP1		"http/1.1"

/**

 * Determine the list of protocols available for a connection/request. This may

 * be collected with or without any request sent, in which case the request is 

 * NULL. Or it may be triggered by the request received, e.g. through the 

 * "Upgrade" header.

 *

 * This hook will be run whenever protocols are being negotiated (ALPN as

 * one example). It may also be invoked at other times, e.g. when the server

 * wants to advertise protocols it is capable of switching to.

 * 

 * The identifiers for protocols are taken from the TLS extension type ALPN:

 * https://www.iana.org/assignments/tls-extensiontype-values/tls-extensiontype-values.xml

 *

 * If no protocols are added to the proposals, the server not perform any

 * switch. If the protocol selected from the proposals is the protocol

 * already in place, also no protocol switch will be invoked.

 *

 * The client may already have announced the protocols it is willing to

 * accept. These will then be listed as offers. This parameter may also

 * be NULL, indicating that offers from the client are not known and

 * the hooks should propose all protocols that are valid for the

 * current connection/request.

 *

 * All hooks are run, unless one returns an error. Proposals may contain

 * duplicates. The order in which proposals are added is usually ignored.

 * 

 * @param c The current connection

 * @param r The current request or NULL

 * @param s The server/virtual host selected

 * @param offers A list of protocol identifiers offered by the client or

 *               NULL to indicated that the hooks are free to propose 

 * @param proposals The list of protocol identifiers proposed by the hooks

 * @return OK or DECLINED

 * @bug This API or implementation and order of operations should be considered

 * experimental and will continue to evolve in future 2.4 releases, with

 * a corresponding minor module magic number (MMN) bump to indicate the

 * API revision level.

 */

AP_DECLARE_HOOK(int,protocol_propose,(conn_rec *c, request_rec *r,

                                      server_rec *s,

                                      const apr_array_header_t *offers,

                                      apr_array_header_t *proposals))

/**

 * Perform a protocol switch on the connection. The exact requirements for

 * that depend on the protocol in place and the one switched to. The first 

 * protocol module to handle the switch is the last module run.

 * 

 * For a connection level switch (r == NULL), the handler must on return

 * leave the conn_rec in a state suitable for processing the switched

 * protocol, e.g. correct filters in place.

 *

 * For a request triggered switch (r != NULL), the protocol switch is done

 * before the response is sent out. When switching from "http/1.1" via Upgrade

 * header, the 101 intermediate response will have been sent. The

 * hook needs then to process the connection until it can be closed. Which

 * the server will enforce on hook return.

 * Any error the hook might encounter must already be sent by the hook itself

 * to the client in whatever form the new protocol requires.

 *

 * @param c The current connection

 * @param r The current request or NULL

 * @param s The server/virtual host selected

 * @param choices A list of protocol identifiers, normally the clients whishes

 * @param proposals the list of protocol identifiers proposed by the hooks

 * @return OK or DECLINED

 * @bug This API or implementation and order of operations should be considered

 * experimental and will continue to evolve in future 2.4 releases, with

 * a corresponding minor module magic number (MMN) bump to indicate the

 * API revision level.

 */

AP_DECLARE_HOOK(int,protocol_switch,(conn_rec *c, request_rec *r,

                                     server_rec *s,

                                     const char *protocol))

/**

 * Return the protocol used on the connection. Modules implementing

 * protocol switching must register here and return the correct protocol

 * identifier for connections they switched.

 *

 * To find out the protocol for the current connection, better call

 * @see ap_get_protocol which internally uses this hook.

 *

 * @param c The current connection

 * @return The identifier of the protocol in place or NULL

 * @bug This API or implementation and order of operations should be considered

 * experimental and will continue to evolve in future 2.4 releases, with

 * a corresponding minor module magic number (MMN) bump to indicate the

 * API revision level.

 */

AP_DECLARE_HOOK(const char *,protocol_get,(const conn_rec *c))

/**

 * Get the protocols that the connection and optional request may

 * upgrade to - besides the protocol currently active on the connection. These

 * values may be used to announce to a client what choices it has.

 *

 * If report_all == 0, only protocols more preferable than the one currently

 * being used, are reported. Otherwise, all available protocols beside the

 * current one are being reported.

 *

 * @param c The current connection

 * @param r The current request or NULL

 * @param s The server/virtual host selected or NULL

 * @param report_all include also protocols less preferred than the current one

 * @param pupgrades on return, possible protocols to upgrade to in descending order 

 *                 of preference. Maybe NULL if none are available.    

 * @bug This API or implementation and order of operations should be considered

 * experimental and will continue to evolve in future 2.4 releases, with

 * a corresponding minor module magic number (MMN) bump to indicate the

 * API revision level.

 */

AP_DECLARE(apr_status_t) ap_get_protocol_upgrades(conn_rec *c, request_rec *r, 

                                                  server_rec *s, int report_all, 

                                                  const apr_array_header_t **pupgrades);

/**

 * Select a protocol for the given connection and optional request. Will return

 * the protocol identifier selected which may be the protocol already in place

 * on the connection. The selected protocol will be NULL if non of the given

 * choices could be agreed upon (e.g. no proposal as made).

 *

 * A special case is where the choices itself is NULL (instead of empty). In

 * this case there are no restrictions imposed on protocol selection.

 *

 * @param c The current connection

 * @param r The current request or NULL

 * @param s The server/virtual host selected

 * @param choices A list of protocol identifiers, normally the clients whishes

 * @return The selected protocol or NULL if no protocol could be agreed upon

 * @bug This API or implementation and order of operations should be considered

 * experimental and will continue to evolve in future 2.4 releases, with

 * a corresponding minor module magic number (MMN) bump to indicate the

 * API revision level.

 */

AP_DECLARE(const char *) ap_select_protocol(conn_rec *c, request_rec *r, 

                                            server_rec *s,

                                            const apr_array_header_t *choices);

/**

 * Perform the actual protocol switch. The protocol given must have been

 * selected before on the very same connection and request pair.

 *