httpd.h

     */
    const char *log_id;

    /**
     * A linked list of the .htaccess configuration directives
     * accessed by this request.
     * N.B. always add to the head of the list, _never_ to the end.
     * that way, a sub request's list can (temporarily) point to a parent's list
     */
    const struct htaccess_result *htaccess;

    /** A list of output filters to be used for this request */
    struct ap_filter_t *output_filters;
    /** A list of input filters to be used for this request */
    struct ap_filter_t *input_filters;

    /** A list of protocol level output filters to be used for this
     *  request */
    struct ap_filter_t *proto_output_filters;
    /** A list of protocol level input filters to be used for this
     *  request */
    struct ap_filter_t *proto_input_filters;

    /** This response can not be cached */
    int no_cache;
    /** There is no local copy of this response */
    int no_local_copy;

    /** Mutex protect callbacks registered with ap_mpm_register_timed_callback
     * from being run before the original handler finishes running
     */
    apr_thread_mutex_t *invoke_mtx;

    /** A struct containing the components of URI */
    apr_uri_t parsed_uri;
    /**  finfo.protection (st_mode) set to zero if no such file */
    apr_finfo_t finfo;

    /** remote address information from conn_rec, can be overridden if
     * necessary by a module.
     * This is the address that originated the request.
     */
    apr_sockaddr_t *useragent_addr;
    char *useragent_ip;

    /** MIME trailer environment from the request */
    apr_table_t *trailers_in;
    /** MIME trailer environment from the response */
    apr_table_t *trailers_out;

    /** Originator's DNS name, if known.  NULL if DNS hasn't been checked,
     *  "" if it has and no address was found.  N.B. Only access this though
     *  ap_get_useragent_host() */
    char *useragent_host;
    /** have we done double-reverse DNS? -1 yes/failure, 0 not yet,
     *  1 yes/success
     */
    int double_reverse;
};

/**
 * @defgroup ProxyReq Proxy request types
 *
 * Possible values of request_rec->proxyreq. A request could be normal,
 *  proxied or reverse proxied. Normally proxied and reverse proxied are
 *  grouped together as just "proxied", but sometimes it's necessary to
 *  tell the difference between the two, such as for authentication.
 * @{
 */

#define PROXYREQ_NONE     0     /**< No proxy */
#define PROXYREQ_PROXY    1     /**< Standard proxy */
#define PROXYREQ_REVERSE  2     /**< Reverse proxy */
#define PROXYREQ_RESPONSE 3     /**< Origin response */

/* @} */

/**
 * @brief Enumeration of connection keepalive options
 */
typedef enum {
    AP_CONN_UNKNOWN,
    AP_CONN_CLOSE,
    AP_CONN_KEEPALIVE
} ap_conn_keepalive_e;

/**
 * @brief Structure to store things which are per connection
 */
struct conn_rec {
    /** Pool associated with this connection */
    apr_pool_t *pool;
    /** Physical vhost this conn came in on */
    server_rec *base_server;
    /** used by http_vhost.c */
    void *vhost_lookup_data;

    /* Information about the connection itself */
    /** local address */
    apr_sockaddr_t *local_addr;
    /** remote address; this is the end-point of the next hop, for the address
     *  of the request creator, see useragent_addr in request_rec
     */
    apr_sockaddr_t *client_addr;

    /** Client's IP address; this is the end-point of the next hop, for the
     *  IP of the request creator, see useragent_ip in request_rec
     */
    char *client_ip;
    /** Client's DNS name, if known.  NULL if DNS hasn't been checked,
     *  "" if it has and no address was found.  N.B. Only access this though
     * get_remote_host() */
    char *remote_host;
    /** Only ever set if doing rfc1413 lookups.  N.B. Only access this through
     *  get_remote_logname() */
    char *remote_logname;

    /** server IP address */
    char *local_ip;
    /** used for ap_get_server_name when UseCanonicalName is set to DNS
     *  (ignores setting of HostnameLookups) */
    char *local_host;

    /** ID of this connection; unique at any point in time */
    long id;
    /** Config vector containing pointers to connections per-server
     *  config structures. */
    struct ap_conf_vector_t *conn_config;
    /** Notes on *this* connection: send note from one module to
     *  another. must remain valid for all requests on this conn */
    apr_table_t *notes;
    /** A list of input filters to be used for this connection */
    struct ap_filter_t *input_filters;
    /** A list of output filters to be used for this connection */
    struct ap_filter_t *output_filters;
    /** handle to scoreboard information for this connection */
    void *sbh;
    /** The bucket allocator to use for all bucket/brigade creations */
    struct apr_bucket_alloc_t *bucket_alloc;
    /** The current state of this connection; may be NULL if not used by MPM */
    conn_state_t *cs;
    /** Is there data pending in the input filters? */
    int data_in_input_filters;
    /** Is there data pending in the output filters? */
    int data_in_output_filters;

    /** Are there any filters that clogg/buffer the input stream, breaking
     *  the event mpm.
     */
    unsigned int clogging_input_filters:1;

    /** have we done double-reverse DNS? -1 yes/failure, 0 not yet,
     *  1 yes/success */
    signed int double_reverse:2;

    /** Are we still talking? */
    unsigned aborted;

    /** Are we going to keep the connection alive for another request?
     * @see ap_conn_keepalive_e */
    ap_conn_keepalive_e keepalive;

    /** How many times have we used it? */
    int keepalives;

    /** Optional connection log level configuration. May point to a server or
     *  per_dir config, i.e. must be copied before modifying */
    const struct ap_logconf *log;

    /** Id to identify this connection in error log. Set when the first
     *  error log entry for this connection is generated.
     */
    const char *log_id;


    /** This points to the current thread being used to process this request,
     * over the lifetime of a request, the value may change. Users of the connection
     * record should not rely upon it staying the same between calls that involve
     * the MPM.
     */
#if APR_HAS_THREADS
    apr_thread_t *current_thread;
#endif

    /** The "real" master connection. NULL if I am the master. */
    conn_rec *master;
};

/**
 * Enumeration of connection states
 * The two states CONN_STATE_LINGER_NORMAL and CONN_STATE_LINGER_SHORT may
 * only be set by the MPM. Use CONN_STATE_LINGER outside of the MPM.
 */
typedef enum  {
    CONN_STATE_CHECK_REQUEST_LINE_READABLE,
    CONN_STATE_READ_REQUEST_LINE,
    CONN_STATE_HANDLER,
    CONN_STATE_WRITE_COMPLETION,
    CONN_STATE_SUSPENDED,
    CONN_STATE_LINGER,          /* connection may be closed with lingering */
    CONN_STATE_LINGER_NORMAL,   /* MPM has started lingering close with normal timeout */
    CONN_STATE_LINGER_SHORT     /* MPM has started lingering close with short timeout */
} conn_state_e;

typedef enum  {
    CONN_SENSE_DEFAULT,
    CONN_SENSE_WANT_READ,       /* next event must be read */
    CONN_SENSE_WANT_WRITE       /* next event must be write */
} conn_sense_e;

/**
 * @brief A structure to contain connection state information
 */
struct conn_state_t {
    /** Current state of the connection */
    conn_state_e state;
    /** Whether to read instead of write, or write instead of read */
    conn_sense_e sense;
};

/* Per-vhost config... */

/**
 * The address 255.255.255.255, when used as a virtualhost address,
 * will become the "default" server when the ip doesn't match other vhosts.
 */
#define DEFAULT_VHOST_ADDR 0xfffffffful


/**
 * @struct server_addr_rec
 * @brief  A structure to be used for Per-vhost config
 */
typedef struct server_addr_rec server_addr_rec;
struct server_addr_rec {
    /** The next server in the list */
    server_addr_rec *next;
    /** The name given in "<VirtualHost>" */
    char *virthost;
    /** The bound address, for this server */
    apr_sockaddr_t *host_addr;
    /** The bound port, for this server */
    apr_port_t host_port;
};

struct ap_logconf {
    /** The per-module log levels */
    signed char *module_levels;

    /** The log level for this server */
    int level;
};
/**
 * @brief A structure to store information for each virtual server
 */
struct server_rec {
    /** The process this server is running in */
    process_rec *process;
    /** The next server in the list */
    server_rec *next;

    /* Log files --- note that transfer log is now in the modules... */

    /** The name of the error log */
    char *error_fname;
    /** A file descriptor that references the error log */
    apr_file_t *error_log;
    /** The log level configuration */
    struct ap_logconf log;

    /* Module-specific configuration for server, and defaults... */

    /** Config vector containing pointers to modules' per-server config
     *  structures. */
    struct ap_conf_vector_t *module_config;
    /** MIME type info, etc., before we start checking per-directory info */
    struct ap_conf_vector_t *lookup_defaults;

    /** The name of the server */
    const char *defn_name;
    /** The line of the config file that the server was defined on */
    unsigned defn_line_number;
    /** true if this is the virtual server */
    char is_virtual;


    /* Information for redirects */

    /** for redirects, etc. */
    apr_port_t port;
    /** The server request scheme for redirect responses */
    const char *server_scheme;

    /* Contact information */

    /** The admin's contact information */
    char *server_admin;
    /** The server hostname */
    char *server_hostname;

    /* Transaction handling */

    /** I haven't got a clue */
    server_addr_rec *addrs;
    /** Timeout, as an apr interval, before we give up */
    apr_interval_time_t timeout;
    /** The apr interval we will wait for another request */
    apr_interval_time_t keep_alive_timeout;
    /** Maximum requests per connection */
    int keep_alive_max;
    /** Use persistent connections? */
    int keep_alive;

    /** Normal names for ServerAlias servers */
    apr_array_header_t *names;
    /** Wildcarded names for ServerAlias servers */
    apr_array_header_t *wild_names;

    /** Pathname for ServerPath */
    const char *path;
    /** Length of path */
    int pathlen;

    /** limit on size of the HTTP request line    */
    int limit_req_line;
    /** limit on size of any request header field */
    int limit_req_fieldsize;
    /** limit on number of request header fields  */
    int limit_req_fields;

    /** Opaque storage location */
    void *context;

    /** Whether the keepalive timeout is explicit (1) or
     *  inherited (0) from the base server (either first
     *  server on the same IP:port or main server) */
    unsigned int keep_alive_timeout_set:1;
};

/**
 * @struct ap_sload_t
 * @brief  A structure to hold server load params
 */
typedef struct ap_sload_t ap_sload_t;
struct ap_sload_t {
    /* percentage of process/threads ready/idle (0->100)*/
    int idle;
    /* percentage of process/threads busy (0->100) */
    int busy;
    /* total bytes served */
    apr_off_t bytes_served;
    /* total access count */
    unsigned long access_count;
};

/**
 * @struct ap_loadavg_t
 * @brief  A structure to hold various server loadavg
 */
typedef struct ap_loadavg_t ap_loadavg_t;
struct ap_loadavg_t {
    /* current loadavg, ala getloadavg() */
    float loadavg;
    /* 5 min loadavg */
    float loadavg5;
    /* 15 min loadavg */
    float loadavg15;
};

/**
 * Get the context_document_root for a request. This is a generalization of
 * the document root, which is too limited in the presence of mappers like
 * mod_userdir and mod_alias. The context_document_root is the directory
 * on disk that maps to the context_prefix URI prefix.
 * @param r The request
 * @note For resources that do not map to the file system or for very complex
 * mappings, this information may still be wrong.
 */
AP_DECLARE(const char *) ap_context_document_root(request_rec *r);

/**
 * Get the context_prefix for a request. The context_prefix URI prefix
 * maps to the context_document_root on disk.
 * @param r The request
 */
AP_DECLARE(const char *) ap_context_prefix(request_rec *r);

/** Set context_prefix and context_document_root for a request.
 * @param r The request
 * @param prefix the URI prefix, without trailing slash
 * @param document_root the corresponding directory on disk, without trailing
 * slash
 * @note If one of prefix of document_root is NULL, the corrsponding
 * property will not be changed.
 */
AP_DECLARE(void) ap_set_context_info(request_rec *r, const char *prefix,
                                     const char *document_root);

/** Set per-request document root. This is for mass virtual hosting modules
 * that want to provide the correct DOCUMENT_ROOT value to scripts.
 * @param r The request
 * @param document_root the document root for the request.
 */
AP_DECLARE(void) ap_set_document_root(request_rec *r, const char *document_root);

/**
 * Examine a field value (such as a media-/content-type) string and return
 * it sans any parameters; e.g., strip off any ';charset=foo' and the like.
 * @param p Pool to allocate memory from
 * @param intype The field to examine
 * @return A copy of the field minus any parameters
 */
AP_DECLARE(char *) ap_field_noparam(apr_pool_t *p, const char *intype);

/**
 * Convert a time from an integer into a string in a specified format
 * @param p The pool to allocate memory from
 * @param t The time to convert
 * @param fmt The format to use for the conversion
 * @param gmt Convert the time for GMT?
 * @return The string that represents the specified time
 */
AP_DECLARE(char *) ap_ht_time(apr_pool_t *p, apr_time_t t, const char *fmt, int gmt);

/* String handling. The *_nc variants allow you to use non-const char **s as
   arguments (unfortunately C won't automatically convert a char ** to a const
   char **) */

/**
 * Get the characters until the first occurrence of a specified character
 * @param p The pool to allocate memory from
 * @param line The string to get the characters from
 * @param stop The character to stop at
 * @return A copy of the characters up to the first stop character
 */
AP_DECLARE(char *) ap_getword(apr_pool_t *p, const char **line, char stop);

/**
 * Get the characters until the first occurrence of a specified character
 * @param p The pool to allocate memory from
 * @param line The string to get the characters from
 * @param stop The character to stop at
 * @return A copy of the characters up to the first stop character
 * @note This is the same as ap_getword(), except it doesn't use const char **.
 */
AP_DECLARE(char *) ap_getword_nc(apr_pool_t *p, char **line, char stop);

/**
 * Get the first word from a given string.  A word is defined as all characters
 * up to the first whitespace.
 * @param p The pool to allocate memory from
 * @param line The string to traverse
 * @return The first word in the line
 */
AP_DECLARE(char *) ap_getword_white(apr_pool_t *p, const char **line);

/**
 * Get the first word from a given string.  A word is defined as all characters
 * up to the first whitespace.
 * @param p The pool to allocate memory from
 * @param line The string to traverse
 * @return The first word in the line
 * @note The same as ap_getword_white(), except it doesn't use const char**
 */
AP_DECLARE(char *) ap_getword_white_nc(apr_pool_t *p, char **line);

/**
 * Get all characters from the first occurrence of @a stop to the first "\0"
 * @param p The pool to allocate memory from
 * @param line The line to traverse
 * @param stop The character to start at
 * @return A copy of all characters after the first occurrence of the specified
 *         character
 */
AP_DECLARE(char *) ap_getword_nulls(apr_pool_t *p, const char **line,
                                    char stop);

/**
 * Get all characters from the first occurrence of @a stop to the first "\0"
 * @param p The pool to allocate memory from
 * @param line The line to traverse
 * @param stop The character to start at
 * @return A copy of all characters after the first occurrence of the specified
 *         character
 * @note The same as ap_getword_nulls(), except it doesn't use const char **.
 */
AP_DECLARE(char *) ap_getword_nulls_nc(apr_pool_t *p, char **line, char stop);

/**
 * Get the second word in the string paying attention to quoting
 * @param p The pool to allocate from
 * @param line The line to traverse
 * @return A copy of the string
 */
AP_DECLARE(char *) ap_getword_conf(apr_pool_t *p, const char **line);

/**
 * Get the second word in the string paying attention to quoting
 * @param p The pool to allocate from
 * @param line The line to traverse
 * @return A copy of the string
 * @note The same as ap_getword_conf(), except it doesn't use const char **.
 */
AP_DECLARE(char *) ap_getword_conf_nc(apr_pool_t *p, char **line);

/**
 * Get the second word in the string paying attention to quoting,
 * with {...} supported as well as "..." and '...'
 * @param p The pool to allocate from
 * @param line The line to traverse
 * @return A copy of the string
 */
AP_DECLARE(char *) ap_getword_conf2(apr_pool_t *p, const char **line);

/**
 * Get the second word in the string paying attention to quoting,
 * with {...} supported as well as "..." and '...'
 * @param p The pool to allocate from
 * @param line The line to traverse
 * @return A copy of the string
 * @note The same as ap_getword_conf2(), except it doesn't use const char **.
 */
AP_DECLARE(char *) ap_getword_conf2_nc(apr_pool_t *p, char **line);

/**
 * Check a string for any config define or environment variable construct
 * and replace each of them by the value of that variable, if it exists.
 * The default syntax of the constructs is ${ENV} but can be changed by
 * setting the define::* config defines. If the variable does not exist,
 * leave the ${ENV} construct alone but print a warning.
 * @param p The pool to allocate from
 * @param word The string to check
 * @return The string with the replaced environment variables
 */
AP_DECLARE(const char *) ap_resolve_env(apr_pool_t *p, const char * word);

/**
 * Size an HTTP header field list item, as separated by a comma.
 * @param field The field to size
 * @param len The length of the field
 * @return The return value is a pointer to the beginning of the non-empty
 * list item within the original string (or NULL if there is none) and the
 * address of field is shifted to the next non-comma, non-whitespace
 * character.  len is the length of the item excluding any beginning whitespace.
 */
AP_DECLARE(const char *) ap_size_list_item(const char **field, int *len);

/**
 * Retrieve an HTTP header field list item, as separated by a comma,
 * while stripping insignificant whitespace and lowercasing anything not in
 * a quoted string or comment.
 * @param p The pool to allocate from
 * @param field The field to retrieve
 * @return The return value is a new string containing the converted list
 *         item (or NULL if none) and the address pointed to by field is
 *         shifted to the next non-comma, non-whitespace.
 */
AP_DECLARE(char *) ap_get_list_item(apr_pool_t *p, const char **field);

/**
 * Find an item in canonical form (lowercase, no extra spaces) within
 * an HTTP field value list.
 * @param p The pool to allocate from
 * @param line The field value list to search
 * @param tok The token to search for
 * @return 1 if found, 0 if not found.
 */
AP_DECLARE(int) ap_find_list_item(apr_pool_t *p, const char *line, const char *tok);

/**
 * Do a weak ETag comparison within an HTTP field value list.
 * @param p The pool to allocate from
 * @param line The field value list to search
 * @param tok The token to search for
 * @return 1 if found, 0 if not found.
 */
AP_DECLARE(int) ap_find_etag_weak(apr_pool_t *p, const char *line, const char *tok);

/**
 * Do a strong ETag comparison within an HTTP field value list.
 * @param p The pool to allocate from
 * @param line The field value list to search
 * @param tok The token to search for
 * @return 1 if found, 0 if not found.
 */
AP_DECLARE(int) ap_find_etag_strong(apr_pool_t *p, const char *line, const char *tok);

/* Scan a string for field content chars, as defined by RFC7230 section 3.2
 * including VCHAR/obs-text, as well as HT and SP
 * @param ptr The string to scan
 * @return A pointer to the first (non-HT) ASCII ctrl character.
 * @note lws and trailing whitespace are scanned, the caller is responsible
 * for trimming leading and trailing whitespace
 */
AP_DECLARE(const char *) ap_scan_http_field_content(const char *ptr);

/* Scan a string for token characters, as defined by RFC7230 section 3.2.6 
 * @param ptr The string to scan
 * @return A pointer to the first non-token character.
 */
AP_DECLARE(const char *) ap_scan_http_token(const char *ptr);

/* Scan a string for visible ASCII (0x21-0x7E) or obstext (0x80+)
 * and return a pointer to the first SP/CTL/NUL character encountered.
 * @param ptr The string to scan
 * @return A pointer to the first SP/CTL character.
 */
AP_DECLARE(const char *) ap_scan_vchar_obstext(const char *ptr);

/**
 * Retrieve an array of tokens in the format "1#token" defined in RFC2616. Only
 * accepts ',' as a delimiter, does not accept quoted strings, and errors on
 * any separator.
 * @param p The pool to allocate from
 * @param tok The line to read tokens from
 * @param tokens Pointer to an array of tokens. If not NULL, must be an array
 *    of char*, otherwise it will be allocated on @a p when a token is found
 * @param skip_invalid If true, when an invalid separator is encountered, it
 *    will be ignored.
 * @return NULL on success, an error string otherwise.
 * @remark *tokens may be NULL on output if NULL in input and no token is found
 */
AP_DECLARE(const char *) ap_parse_token_list_strict(apr_pool_t *p, const char *tok,
                                                    apr_array_header_t **tokens,
                                                    int skip_invalid);

/**
 * Retrieve a token, spacing over it and adjusting the pointer to
 * the first non-white byte afterwards.  Note that these tokens
 * are delimited by semis and commas and can also be delimited
 * by whitespace at the caller's option.
 * @param p The pool to allocate from
 * @param accept_line The line to retrieve the token from (adjusted afterwards)
 * @param accept_white Is it delimited by whitespace
 * @return the token
 */
AP_DECLARE(char *) ap_get_token(apr_pool_t *p, const char **accept_line, int accept_white);

/**
 * Find http tokens, see the definition of token from RFC2068
 * @param p The pool to allocate from
 * @param line The line to find the token
 * @param tok The token to find
 * @return 1 if the token is found, 0 otherwise
 */
AP_DECLARE(int) ap_find_token(apr_pool_t *p, const char *line, const char *tok);

/**
 * find http tokens from the end of the line
 * @param p The pool to allocate from
 * @param line The line to find the token
 * @param tok The token to find
 * @return 1 if the token is found, 0 otherwise
 */
AP_DECLARE(int) ap_find_last_token(apr_pool_t *p, const char *line, const char *tok);

/**
 * Check for an Absolute URI syntax
 * @param u The string to check
 * @return 1 if URI, 0 otherwise
 */
AP_DECLARE(int) ap_is_url(const char *u);

/**
 * Unescape a string
 * @param url The string to unescape
 * @return 0 on success, non-zero otherwise
 */
AP_DECLARE(int) ap_unescape_all(char *url);

/**
 * Unescape a URL
 * @param url The url to unescape
 * @return 0 on success, non-zero otherwise
 */
AP_DECLARE(int) ap_unescape_url(char *url);

/**
 * Unescape a URL, but leaving %2f (slashes) escaped
 * @param url The url to unescape
 * @param decode_slashes Whether or not slashes should be decoded
 * @return 0 on success, non-zero otherwise
 */
AP_DECLARE(int) ap_unescape_url_keep2f(char *url, int decode_slashes);

/**
 * Unescape an application/x-www-form-urlencoded string
 * @param query The query to unescape
 * @return 0 on success, non-zero otherwise
 */
AP_DECLARE(int) ap_unescape_urlencoded(char *query);

/**
 * Convert all double slashes to single slashes
 * @param name The string to convert
 */
AP_DECLARE(void) ap_no2slash(char *name);

/**
 * Remove all ./ and xx/../ substrings from a file name. Also remove
 * any leading ../ or /../ substrings.
 * @param name the file name to parse
 */
AP_DECLARE(void) ap_getparents(char *name);

/**
 * Escape a path segment, as defined in RFC 1808
 * @param p The pool to allocate from
 * @param s The path to convert
 * @return The converted URL
 */
AP_DECLARE(char *) ap_escape_path_segment(apr_pool_t *p, const char *s);

/**
 * Escape a path segment, as defined in RFC 1808, to a preallocated buffer.
 * @param c The preallocated buffer to write to
 * @param s The path to convert
 * @return The converted URL (c)
 */
AP_DECLARE(char *) ap_escape_path_segment_buffer(char *c, const char *s);

/**
 * convert an OS path to a URL in an OS dependent way.
 * @param p The pool to allocate from
 * @param path The path to convert
 * @param partial if set, assume that the path will be appended to something
 *        with a '/' in it (and thus does not prefix "./")
 * @return The converted URL
 */
AP_DECLARE(char *) ap_os_escape_path(apr_pool_t *p, const char *path, int partial);

/** @see ap_os_escape_path */
#define ap_escape_uri(ppool,path) ap_os_escape_path(ppool,path,1)

/**
 * Escape a string as application/x-www-form-urlencoded
 * @param p The pool to allocate from
 * @param s The path to convert
 * @return The converted URL
 */
AP_DECLARE(char *) ap_escape_urlencoded(apr_pool_t *p, const char *s);

/**
 * Escape a string as application/x-www-form-urlencoded, to a preallocated buffer
 * @param c The preallocated buffer to write to
 * @param s The path to convert
 * @return The converted URL (c)
 */
AP_DECLARE(char *) ap_escape_urlencoded_buffer(char *c, const char *s);

/**
 * Escape an html string
 * @param p The pool to allocate from
 * @param s The html to escape
 * @return The escaped string
 */
#define ap_escape_html(p,s) ap_escape_html2(p,s,0)
/**
 * Escape an html string
 * @param p The pool to allocate from
 * @param s The html to escape
 * @param toasc Whether to escape all non-ASCII chars to \&\#nnn;
 * @return The escaped string
 */
AP_DECLARE(char *) ap_escape_html2(apr_pool_t *p, const char *s, int toasc);

/**
 * Escape a string for logging
 * @param p The pool to allocate from
 * @param str The string to escape
 * @return The escaped string
 */
AP_DECLARE(char *) ap_escape_logitem(apr_pool_t *p, const char *str);

/**
 * Escape a string for logging into the error log (without a pool)
 * @param dest The buffer to write to
 * @param source The string to escape
 * @param buflen The buffer size for the escaped string (including "\0")
 * @return The len of the escaped string (always < maxlen)
 */
AP_DECLARE(apr_size_t) ap_escape_errorlog_item(char *dest, const char *source,
                                               apr_size_t buflen);

/**
 * Construct a full hostname
 * @param p The pool to allocate from
 * @param hostname The hostname of the server
 * @param port The port the server is running on
 * @param r The current request
 * @return The server's hostname
 */
AP_DECLARE(char *) ap_construct_server(apr_pool_t *p, const char *hostname,
                                    apr_port_t port, const request_rec *r);

/**
 * Escape a shell command
 * @param p The pool to allocate from
 * @param s The command to escape
 * @return The escaped shell command
 */
AP_DECLARE(char *) ap_escape_shell_cmd(apr_pool_t *p, const char *s);

/**
 * Count the number of directories in a path
 * @param path The path to count
 * @return The number of directories
 */
AP_DECLARE(int) ap_count_dirs(const char *path);

/**
 * Copy at most @a n leading directories of @a s into @a d. @a d
 * should be at least as large as @a s plus 1 extra byte
 *
 * @param d The location to copy to
 * @param s The location to copy from
 * @param n The number of directories to copy
 * @return value is the ever useful pointer to the trailing "\0" of d
 * @note on platforms with drive letters, n = 0 returns the "/" root,
 * whereas n = 1 returns the "d:/" root.  On all other platforms, n = 0
 * returns the empty string.  */
AP_DECLARE(char *) ap_make_dirstr_prefix(char *d, const char *s, int n);

/**
 * Return the parent directory name (including trailing /) of the file
 * @a s
 * @param p The pool to allocate from
 * @param s The file to get the parent of
 * @return A copy of the file's parent directory
 */
AP_DECLARE(char *) ap_make_dirstr_parent(apr_pool_t *p, const char *s);

/**
 * Given a directory and filename, create a single path from them.  This
 * function is smart enough to ensure that there is a single '/' between the
 * directory and file names
 * @param a The pool to allocate from
 * @param dir The directory name
 * @param f The filename
 * @return A copy of the full path
 * @note Never consider using this function if you are dealing with filesystem
 * names that need to remain canonical, unless you are merging an apr_dir_read
 * path and returned filename.  Otherwise, the result is not canonical.
 */
AP_DECLARE(char *) ap_make_full_path(apr_pool_t *a, const char *dir, const char *f);

/**
 * Test if the given path has an absolute path.
 * @param p The pool to allocate from
 * @param dir The directory name
 * @note The converse is not necessarily true, some OS's (Win32/OS2/Netware) have
 * multiple forms of absolute paths.  This only reports if the path is absolute
 * in a canonical sense.
 */
AP_DECLARE(int) ap_os_is_path_absolute(apr_pool_t *p, const char *dir);

/**
 * Does the provided string contain wildcard characters?  This is useful
 * for determining if the string should be passed to strcmp_match or to strcmp.
 * The only wildcard characters recognized are '?' and '*'
 * @param str The string to check
 * @return 1 if the string has wildcards, 0 otherwise
 */
AP_DECLARE(int) ap_is_matchexp(const char *str);

/**
 * Determine if a string matches a pattern containing the wildcards '?' or '*'
 * @param str The string to check
 * @param expected The pattern to match against
 * @return 0 if the two strings match, 1 otherwise
 */
AP_DECLARE(int) ap_strcmp_match(const char *str, const char *expected);

/**
 * Determine if a string matches a pattern containing the wildcards '?' or '*',
 * ignoring case
 * @param str The string to check
 * @param expected The pattern to match against
 * @return 0 if the two strings match, 1 otherwise
 */
AP_DECLARE(int) ap_strcasecmp_match(const char *str, const char *expected);

/**
 * Find the first occurrence of the substring s2 in s1, regardless of case
 * @param s1 The string to search
 * @param s2 The substring to search for
 * @return A pointer to the beginning of the substring
 * @remark See apr_strmatch() for a faster alternative
 */
AP_DECLARE(char *) ap_strcasestr(const char *s1, const char *s2);

/**
 * Return a pointer to the location inside of bigstring immediately after prefix
 * @param bigstring The input string
 * @param prefix The prefix to strip away
 * @return A pointer relative to bigstring after prefix
 */
AP_DECLARE(const char *) ap_stripprefix(const char *bigstring,
                                        const char *prefix);

/**
 * Decode a base64 encoded string into memory allocated from a pool
 * @param p The pool to allocate from
 * @param bufcoded The encoded string
 * @return The decoded string
 */
AP_DECLARE(char *) ap_pbase64decode(apr_pool_t *p, const char *bufcoded);

/**
 * Encode a string into memory allocated from a pool in base 64 format
 * @param p The pool to allocate from
 * @param string The plaintext string
 * @return The encoded string
 */
AP_DECLARE(char *) ap_pbase64encode(apr_pool_t *p, char *string);

/**
 * Compile a regular expression to be used later. The regex is freed when
 * the pool is destroyed.
 * @param p The pool to allocate from
 * @param pattern the regular expression to compile
 * @param cflags The bitwise or of one or more of the following:
 *   @li REG_EXTENDED - Use POSIX extended Regular Expressions
 *   @li REG_ICASE    - Ignore case
 *   @li REG_NOSUB    - Support for substring addressing of matches
 *       not required
 *   @li REG_NEWLINE  - Match-any-character operators don't match new-line
 * @return The compiled regular expression
 */
AP_DECLARE(ap_regex_t *) ap_pregcomp(apr_pool_t *p, const char *pattern,
                                     int cflags);

/**
 * Free the memory associated with a compiled regular expression
 * @param p The pool the regex was allocated from
 * @param reg The regular expression to free
 * @note This function is only necessary if the regex should be cleaned
 * up before the pool
 */
AP_DECLARE(void) ap_pregfree(apr_pool_t *p, ap_regex_t *reg);

/**
 * After performing a successful regex match, you may use this function to
 * perform a series of string substitutions based on subexpressions that were
 * matched during the call to ap_regexec. This function is limited to
 * result strings of 64K. Consider using ap_pregsub_ex() instead.
 * @param p The pool to allocate from
 * @param input An arbitrary string containing $1 through $9.  These are
 *              replaced with the corresponding matched sub-expressions
 * @param source The string that was originally matched to the regex
 * @param nmatch the nmatch returned from ap_pregex
 * @param pmatch the pmatch array returned from ap_pregex
 * @return The substituted string, or NULL on error
 */
AP_DECLARE(char *) ap_pregsub(apr_pool_t *p, const char *input,
                              const char *source, apr_size_t nmatch,
                              ap_regmatch_t pmatch[]);

/**
 * After performing a successful regex match, you may use this function to
 * perform a series of string substitutions based on subexpressions that were
 * matched during the call to ap_regexec
 * @param p The pool to allocate from
 * @param result where to store the result, will be set to NULL on error
 * @param input An arbitrary string containing $1 through $9.  These are
 *              replaced with the corresponding matched sub-expressions
 * @param source The string that was originally matched to the regex
 * @param nmatch the nmatch returned from ap_pregex
 * @param pmatch the pmatch array returned from ap_pregex
 * @param maxlen the maximum string length to return, 0 for unlimited
 * @return APR_SUCCESS if successful, APR_ENOMEM or other error code otherwise.
 */
AP_DECLARE(apr_status_t) ap_pregsub_ex(apr_pool_t *p, char **result,
                                       const char *input, const char *source,
                                       apr_size_t nmatch,
                                       ap_regmatch_t pmatch[],
                                       apr_size_t maxlen);

/**
 * We want to downcase the type/subtype for comparison purposes
 * but nothing else because ;parameter=foo values are case sensitive.
 * @param s The content-type to convert to lowercase
 */
AP_DECLARE(void) ap_content_type_tolower(char *s);

/**
 * convert a string to all lowercase
 * @param s The string to convert to lowercase
 */
AP_DECLARE(void) ap_str_tolower(char *s);

/**
 * convert a string to all uppercase
 * @param s The string to convert to uppercase
 */
AP_DECLARE(void) ap_str_toupper(char *s);

/**
 * Search a string from left to right for the first occurrence of a
 * specific character