Access Manager

This module keeps a list of valid protocol (naming scheme) specifiers with associated access code. It allows documents to be loaded given various combinations of parameters. New access protocols may be registered at any time.

Note: HTRequest defined and request parameter added to almost all calls 18 Nov 1993.

This document is a part of the libwww library. The code is implemented in HTAcces.c

#ifndef HTACCESS_H
#define HTACCESS_H
#include "HTList.h"

Short Names

#ifdef SHORT_NAMES
#define HTClientHost 		HTClHost
#define HTSearchAbsolute	HTSeAbso
#define HTOutputStream		HTOuStre
#define HTOutputFormat		HTOuForm
#endif

Flags which may be set to control this module

extern char * HTSaveLocallyDir;		/* Dir home for "save locally" files */
extern char * HTCacheDir;		/* Cache dir, default NULL: no cache */
extern char * HTClientHost;		/* Name or number of telnetting host */
extern FILE * HTlogfile;		/* File to output one-liners to */
extern BOOL HTSecure;			/* Disable security holes? */
extern char * HTImServer;		/* If I'm cern_httpd */
extern BOOL HTImProxy;			/* If I'm cern_httpd as a proxy */
extern BOOL HTForceReload;		/* Force reload from cache or net */

Method Management

Thesse are the valid methods, see HTTP Methods

typedef enum {
	METHOD_INVALID	= 0,
	METHOD_GET	= 1,
	METHOD_HEAD,
	METHOD_POST,
	METHOD_PUT,
	METHOD_DELETE,
	METHOD_CHECKOUT,
	METHOD_CHECKIN,
	METHOD_SHOWMETHOD,
	METHOD_LINK,
	METHOD_UNLINK,
	MAX_METHODS
} HTMethod;

Get Method Enumeration

Gives the enumeration value of the method as a function of the (char *) name.

PUBLIC HTMethod HTMethod_enum PARAMS((char * name));

Get Method String

The reverse of HTMethod_enum()

PUBLIC char * HTMethod_name PARAMS((HTMethod method));

Valid Methods

This functions searches the list of valid methods for a given anchor, see HTAnchor module If the method is found it returns YES else NO.

PUBLIC BOOL HTMethod_inList PARAMS((HTMethod	method,
				    HTList *	list));

This section might be move to the Access Authentication Module

Match Template Against Filename

/* PUBLIC						HTAA_templateMatch()
**		STRING COMPARISON FUNCTION FOR FILE NAMES
**		   WITH ONE WILDCARD * IN THE TEMPLATE
** NOTE:
**	This is essentially the same code as in HTRules.c, but it
**	cannot be used because it is embedded in between other code.
**	(In fact, HTRules.c should use this routine, but then this
**	 routine would have to be more sophisticated... why is life
**	 sometimes so hard...)
**
** ON ENTRY:
**	template	is a template string to match the file name
**			agaist, may contain a single wildcard
**			character * which matches zero or more
**			arbitrary characters.
**	filename	is the filename (or pathname) to be matched
**			agaist the template.
**
** ON EXIT:
**	returns		YES, if filename matches the template.
**			NO, otherwise.
*/
PUBLIC BOOL HTAA_templateMatch PARAMS((CONST char * template, 
				       CONST char * filename));

The following have to be defined in advance of the other include files because of circular references.

typedef struct _HTRequest HTRequest;

/*
** Callback to call when username and password
** have been prompted.
*/
typedef int (*HTRetryCallbackType) PARAMS((HTRequest * req));


#include "HTAnchor.h"
#include "HTFormat.h"
#include "HTAAUtil.h"		/* HTAAScheme, HTAAFailReason */
#include "HTAABrow.h"		/* HTAASetup */

Default WWW Addresses

These control the home page selection. To mess with these for normal browses is asking for user confusion.

#define LOGICAL_DEFAULT "WWW_HOME"	      /* Defined to be the home page */

#ifndef PERSONAL_DEFAULT
#define PERSONAL_DEFAULT "WWW/default.html"		/* in home directory */
#endif

#ifndef LOCAL_DEFAULT_FILE
#define LOCAL_DEFAULT_FILE "/usr/local/lib/WWW/default.html"
#endif

/* If one telnets to an access point it will look in this file for home page */
#ifndef REMOTE_POINTER
#define REMOTE_POINTER  "/etc/www-remote.url"		    /* can't be file */
#endif

/* and if that fails it will use this. */
#ifndef REMOTE_ADDRESS
#define REMOTE_ADDRESS  "http://info.cern.ch/remote.html"   /* can't be file */
#endif

/* If run from telnet daemon and no -l specified, use this file: */
#ifndef DEFAULT_LOGFILE
#define DEFAULT_LOGFILE	"/usr/adm/www-log/www-log"
#endif

/* If the home page isn't found, use this file: */
#ifndef LAST_RESORT
#define LAST_RESORT	"http://info.cern.ch/default.html"
#endif

/* This is the default cache directory: */
#ifndef CACHE_HOME_DIR
#define CACHE_HOME_DIR		"/tmp/"
#endif

/* The default directory for "save locally" and "save and execute" files: */
#ifndef SAVE_LOCALLY_HOME_DIR
#define SAVE_LOCALLY_HOME_DIR	"/tmp/"
#endif

Protocol Specific Information

This structure contains information about socket number, input buffer for reading from the network etc. The structure is used through out the protocol modules and is the refenrence point for introducing multi threaded execution into the library, see specifications on Multiple Threads.

typedef struct _HTNetInfo {
    int			sockfd;				/* Socket descriptor */
    HTInputSocket *	isoc;				     /* Input buffer */
    int 		addressCount;	     /* Attempts if multi-homed host */
    BOOL		CRLFdotCRLF;  /* Does the transmission end like this */
    struct _HTRequest *	request;	   /* Link back to request structure */
} HTNetInfo;

Note: The AddressCount varaible is used to count the number of attempt to connect to a multi-homed host so we know when to stop trying new IP-addresses.

The Request structure

When a request is handled, all kinds of things about it need to be passed along. These are all put into a HTRequest structure.

Note 1: There is also a global list of converters

Note 2: If you reuse the request structure for more than one request then make sure that the request is re-initialized, so that no `old' data is reused, see functions to manipulate HTRequest Structure. The library handles its own internal information from request to request but the information set by the caller is untouched.

struct _HTRequest {

The elements of the request structure are as follows.

Set by the caller of HTaccess:

Conditions of the request itself:

	HTMethod	method;

An atom for the name of the operation using HTTP method names .

	HTList * 	conversions ;

NULL, or a list of conversions which the format manager can do in order to fulfill the request. This is set by the caller of HTAccess. Typically points to a list set up an initialisation time for example by HTInit.

	HTList *	encodings;	/* allowed content-encodings	  */

The list of encodings acceptablein the output stream.

	HTList *	languages;	/* accepted content-languages	  */

The list of (human) language values acceptable in the response

	BOOL (* callback ) PARAMS((
				struct _HTRequest* request,
				void *param));

A function to be called back in the event that a file has been saved to disk by HTSaveAndCallBack for example.

	void *		context;	/* caller data -- HTAccess unaware */

An arbitrary pointer passed to HTAccess and passed back as a parameter to the callback .

	HTStream*	output_stream;

NULL in the case of display to the user, or if a specific output stream is required, the stream.

	HTAtom * 	output_format;

The output format required, or a generic format such as www/present (present to user).

Information about the requester

	char *		from;

Email format address of person responible for request, see From field in HTTP Protocol. The default address used is the current location, but that can be changed, see HTTCP module.

The URI from which this request was obtained

	HTParentAnchor *parentAnchor;

If this parameter is set then a `Referer: <parent address> is generated in the request to the server, see Referer field in a HTTP Request

Set by HTAccess

None of the bits below may be looked at by a client application except in the callback routine, when the anchor may be picked out.

	HTParentAnchor*	anchor;

The anchor for the object in question. Set immediately by HTAcesss. Used by the protocol and parsing modules. Valid thoughout the access.

	HTChildAnchor *	childAnchor;	/* For element within the object  */

The anchor for the sub object if any. The object builder should ensure that htis is selected, highlighted, etc when the object is loaded. NOTE: Set by HTAccess.

	void *		using_cache;

pointer to cache element if cache hit

Error Diagnostics

	BOOL		error_block;	/* YES if stream has been used	  */
	HTList *	error_stack;	/* List of errors		  */

Library Side

	HTNetInfo *	net_info;	/* Information about socket etc. */
	int		redirections;	/* Number of redirections */

Server Side

	HTAtom *	content_type;	/* Content-Type:		  */
	HTAtom *	content_language;/* Language			  */
	HTAtom *	content_encoding;/* Encoding			  */
	int		content_length;	/* Content-Length:		  */
	HTInputSocket *	isoc;		/* InputSocket object for reading */
	char *		authorization;	/* Authorization: field		  */
	HTAAScheme	scheme;		/* Authentication scheme used	  */

Client Side

	HTList *	valid_schemes;	/* Valid auth.schemes		  */
	HTAssocList **	scheme_specifics;/* Scheme-specific parameters	  */
	char *		prot_template;	/* WWW-Protection-Template: field */
	HTAASetup *	setup;		/* Doc protection info		  */
	HTAARealm *	realm;		/* Password realm		  */
	char *		dialog_msg;	/* Authentication prompt (client) */
	HTRetryCallbackType
			retry_callback;	/* Called when password entered	  */
};

Functions to Manipulate a HTRequest Structure

Just to make things easier especially for clients, here are some functions to manipulate the request structure:

Create blank request

This request has defaults in -- in most cases it will need some information added before being passed to HTAccess, but it will work as is for a simple request.

PUBLIC HTRequest * HTRequest_new NOPARAMS;

Delete request structure

Frees also conversion list hanging from req->conversions.

PUBLIC void HTRequest_delete PARAMS((HTRequest * req));

Clear a request structure

Clears a request structure so that it can be reused. The only thing that differs from using free/new is that the list of conversions is kept.

extern void HTRequest_clear PARAMS((HTRequest * req));

Load a document from relative name

On Entry,

relative_name: The relative address of the file to be accessed.
here: The anchor of the object being searched
request->anchor: not filled in yet

On Exit,

returns YES: Success in opening file
NO: Failure

extern  BOOL HTLoadRelative PARAMS((
		CONST char * 		relative_name,
		HTParentAnchor *	here,
		HTRequest *		request));

Load a document from absolute name

On Entry,

addr: The absolute address of the document to be accessed.
filter: if YES, treat document as HTML
request->anchor: not filled in yet

On Exit,

returns YES: Success in opening document
NO: Failure

extern BOOL HTLoadAbsolute PARAMS((CONST char * addr,
		HTRequest *		request));

Load a document from absolute name to a stream

On Entry,

addr: The absolute address of the document to be accessed.
filter: if YES, treat document as HTML
request->anchor: not filled in yet

On Exit,

returns YES: Success in opening document
NO: Failure

Note: This is equivalent to HTLoadDocument

extern BOOL HTLoadToStream PARAMS((
		CONST char * 		addr,
		BOOL 			filter,
		HTRequest *		request));

Load if necessary, and select an anchor

The anchor parameter may be a child anchor. The anchor in the request is set to the parent anchor. The recursive function keeps the error stack in the request structure so that no information is lost having more than one call.

On Entry,

anchor: may be a child or parenet anchor or 0 in which case there is no effect.
request->anchor: Not set yet.

On Exit,

returns YES: Success
returns NO: Failure
request->anchor: The parenet anchor.

extern BOOL HTLoadAnchor PARAMS((HTAnchor  * a,
				 HTRequest *		request));
extern BOOL HTLoadAnchorRecursive PARAMS((HTAnchor  * a,
				 	  HTRequest *		request));

Load a Document

This is an internal routine, which has an address AND a matching anchor. (The public routines are called with one OR the other.) This is recursively called from file load module to try ftp (though this will be obsolete in the next major release).

On entry,

request->

anchor: a parent anchor with fully qualified hypertext reference as its address set
output_format: valid
output_stream: valid on NULL

keep_error_stack

If this is set to YES then the error (or info) stack is not cleared from the previous call.

On exit,

returns

<0: Error has occured.
HT_LOADED: Success
HT_NO_DATA: Success, but no document loaded. (telnet sesssion started etc)

PUBLIC int HTLoad PARAMS((HTRequest * request, BOOL keep_error_stack));

Bind an anchor to a request structure without loading

The anchor parameter may be a child anchor. The anchor in the request is set to the parent anchor. This is useful in non-interactive mode if no home-anchor is known. Actually the same as HTLoadAnchor(), but without loading

On Entry,

anchor: may be a child or parenet anchor or 0 in which case there is no effect.
request->anchor: Not set yet.

On Exit,

returns YES Success

returns NO Failure

request->anchor The parenet anchor.

extern BOOL HTBindAnchor PARAMS((HTAnchor *anchor, HTRequest *request));

Make a stream for Saving object back

On Entry,

request->anchor: is valid anchor which has previously beeing loaded

On exit,

returns: 0 if error else a stream to save the object to.


extern HTStream * HTSaveStream PARAMS((HTRequest * request));

Search

Performs a search on word given by the user. Adds the search words to the end of the current address and attempts to open the new address.

On Entry,

*keywords: space-separated keyword list or similar search list
here: The anchor of the object being searched

extern BOOL HTSearch PARAMS((
		CONST char *		keywords,
		HTParentAnchor*		here,
		HTRequest *		request));

Search Given Indexname

Performs a keyword search on word given by the user. Adds the keyword to the end of the current address and attempts to open the new address.

On Entry,

*keywords: space-separated keyword list or similar search list
*indexname: is name of object search is to be done on.

extern BOOL HTSearchAbsolute PARAMS((
	CONST char * 		keywords,
	CONST char * 		indexname,
	HTRequest *		request));

Register an access method

An access method is defined by an HTProtocol structure which point to the routines for performing the various logical operations on an object: in HTTP terms, GET, PUT, and POST.

Each of these routine takes as a parameter a request structure containing details ofthe request. When the protocol class routine is called, the anchor elemnt in the request is already valid (made valid by HTAccess).

typedef struct _HTProtocol {
	char * name;
	
	int (*load)PARAMS((HTRequest *	request));
		
	HTStream* (*saveStream)PARAMS((HTRequest *	request));

	HTStream* (*postStream)PARAMS((
				HTRequest *	request,
				HTParentAnchor* postTo));

} HTProtocol;

extern BOOL HTRegisterProtocol PARAMS((HTProtocol * protocol));

Generate the anchor for the home page

As it involves file access, this should only be done once when the program first runs. This is a default algorithm -- browser don't HAVE to use this.

extern HTParentAnchor * HTHomeAnchor NOPARAMS;

#endif /* HTACCESS_H */

end of HTAccess