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<TITLE>HTAccess: Access manager for libwww</TITLE>
<NEXTID N="z11">
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<H1>Access Manager</H1>
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.<P>
<B>Note:</B> HTRequest defined and request parameter added to almost all calls
18 Nov 1993.<P>
This document is a part of the <A NAME="z0" HREF="Overview.html">
libwww library</A>. The code is implemented in <A NAME="z8" HREF="HTAccess.c">
HTAcces.c</A>
<PRE>
#ifndef HTACCESS_H
#define HTACCESS_H
#include "HTList.h"
</PRE>
<B>Short Names</B>
<PRE>
#ifdef SHORT_NAMES
#define HTClientHost HTClHost
#define HTSearchAbsolute HTSeAbso
#define HTOutputStream HTOuStre
#define HTOutputFormat HTOuForm
#endif
</PRE>
<H2>Flags which may be set to control this module</H2>
<PRE>
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 */
</PRE>
<H2>Method Management</H2>
Thesse are the valid methods, see <A HREF="http://info.cern.ch/hypertext/WWW/Protocols/HTTP/Methods.html">HTTP Methods</A>
<PRE>
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;
</PRE>
<H3>Get Method Enumeration</H3>
Gives the enumeration value of the method as a function of the (char *) name.
<PRE>
PUBLIC HTMethod HTMethod_enum PARAMS((char * name));
</PRE>
<H3>Get Method String</H3>
The reverse of <I>HTMethod_enum()</I>
<PRE>
PUBLIC char * HTMethod_name PARAMS((HTMethod method));
</PRE>
<H3>Valid Methods</H3>
This functions searches the list of valid methods for a given anchor, see
<A HREF="HTAnchor.html">HTAnchor module</A> If the method is found it returns
YES else NO.
<PRE>
PUBLIC BOOL HTMethod_inList PARAMS((HTMethod method,
HTList * list));
</PRE>
<HR>
<EM>This section might be move to the Access Authentication Module</EM>
<H4>Match Template Against Filename</H4>
<PRE>
/* 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));
</PRE>
<HR>
The following have to be defined
in advance of the other include files
because of circular references.
<PRE>
typedef struct _HTRequest HTRequest;
/*
** Callback to call when username and password
** have been prompted.
*/
typedef int (*HTRetryCallbackType) PARAMS((HTRequest * req));
#include "HTAnchor.h"
#include <A
NAME="z3" HREF="HTFormat.html">"HTFormat.h"</A>
#include "HTAAUtil.h" /* HTAAScheme, HTAAFailReason */
#include "HTAABrow.h" /* HTAASetup */
</PRE>
<H2>Default WWW Addresses</H2>
These control the home page selection. To mess with these for normal browses
is asking for user confusion.
<PRE>
#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
</PRE>
<H2><A NAME="HTNetInfo">Protocol Specific Information</A></H2>
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 <A HREF="http://info.cern.ch/hypertext/WWW/Library/User/Multithread/multithread.html">Multiple Threads</A>.
<PRE>
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;
</PRE>
<EM><B>Note:</B> 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.</EM>
<H2><A
NAME="z1">The Request structure</A></H2>When a request is handled, all kinds
of things about it need to be passed
along. These are all put into a
HTRequest structure. <P>
<B>Note 1:</B> There is also a <A NAME="z4" HREF="HTFormat.html#z17">global list of converters</A> <P>
<B>Note 2:</B> 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 <A HREF="#z100">functions to manipulate HTRequest
Structure</A>. The library handles its own internal information from request
to request but the information set by the caller is untouched.
<PRE>struct _HTRequest {
</PRE>The elements of the request structure
are as follows.
<H3>Set by the caller of HTaccess:</H3>
<H4>Conditions of the request itself:</H4>
<PRE> HTMethod method;
</PRE>An atom for the name of the operation
using HTTP <A
NAME="z7" HREF="../../Protocols/HTTP/Methods.html">method names</A> .
<PRE> HTList * conversions ;
</PRE>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.
<PRE> HTList * encodings; /* allowed content-encodings */
</PRE>The list of encodings acceptablein
the output stream.
<PRE> HTList * languages; /* accepted content-languages */
</PRE>The list of (human) language values
acceptable in the response
<PRE> BOOL (*<A
NAME="z9"> callback</A> ) PARAMS((
struct _HTRequest* request,
void *param));
</PRE>A function to be called back in the
event that a file has been saved
to disk by HTSaveAndCallBack for
example.
<PRE> void * context; /* caller data -- HTAccess unaware */
</PRE>An arbitrary pointer passed to HTAccess
and passed back as a parameter to
the <A
NAME="z10" HREF="#z9">callback</A> .
<PRE> HTStream* output_stream;
</PRE>NULL in the case of display to the
user, or if a specific output stream
is required, the stream.
<PRE> HTAtom * output_format;
</PRE>The output format required, or a
generic format such as www/present
(present to user).
<H4>Information about the requester</H4>
<PRE> char * from;
</PRE>
Email format address of person responible for request, see <A HREF="http://info.cern.ch/hypertext/WWW/Protocols/HTTP/HTRQ_Headers.html#from">From field in
HTTP Protocol</A>. The default address used is the current location, but that
can be changed, see <A HREF="HTTCP.html#HTGetHostName">HTTCP module</A>.
<H4>The URI from which this request was obtained</H4>
<PRE> HTParentAnchor *parentAnchor;
</PRE>
If this parameter is set then a `Referer: <parent address> is generated
in the request to the server, see <A HREF="http://info.cern.ch/hypertext/WWW/Protocols/HTTP/HTRQ_Headers.html#z14">Referer field in a HTTP Request</A>
<H3>Set by HTAccess</H3>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.
<PRE> HTParentAnchor* anchor;
</PRE>The anchor for the object in question.
Set immediately by HTAcesss. Used
by the protocol and parsing modules.
Valid thoughout the access.
<PRE> HTChildAnchor * childAnchor; /* For element within the object */
</PRE>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.
<PRE> void * using_cache;
</PRE>pointer to cache element if cache
hit
<H3>Error Diagnostics</H3>
<PRE>
BOOL error_block; /* YES if stream has been used */
HTList * error_stack; /* List of errors */
</PRE>
<H3>Library Side</H3>
<PRE>
HTNetInfo * net_info; /* Information about socket etc. */
int redirections; /* Number of redirections */
</PRE>
<H3>Server Side</H3>
<PRE>
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 */
</PRE>
<H3>Client Side</H3>
<PRE>
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 */
};
</PRE>
<H2><A NAME="z100">Functions to Manipulate a HTRequest Structure</A></H2>
Just to make things easier especially for clients, here are some functions to
manipulate the request structure:
<H3>Create blank request</H3>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.
<PRE>
PUBLIC HTRequest * HTRequest_new NOPARAMS;
</PRE>
<H3>Delete request structure</H3>Frees also conversion list hanging
from req->conversions.
<PRE>
PUBLIC void HTRequest_delete PARAMS((HTRequest * req));
</PRE>
<H3>Clear a request structure</H3>
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.
<PRE>
extern void HTRequest_clear PARAMS((HTRequest * req));
</PRE>
<H2>Load a document from relative name</H2>
<H3>On Entry,</H3>
<DL>
<DT>relative_name
<DD> The relative address
of the file to be accessed.
<DT>here
<DD> The anchor of the object being
searched
<DT>request->anchor
<DD> not filled in yet
</DL>
<H3>On Exit,</H3>
<DL>
<DT>returns YES
<DD> Success in opening
file
<DT>NO
<DD> Failure
</DL>
<PRE>extern BOOL HTLoadRelative PARAMS((
CONST char * relative_name,
HTParentAnchor * here,
HTRequest * request));
</PRE>
<H2>Load a document from absolute name</H2>
<H3>On Entry,</H3>
<DL>
<DT>addr
<DD> The absolute address of the
document to be accessed.
<DT>filter
<DD> if YES, treat document as
HTML
<DT>request->anchor
<DD> not filled in yet
</DL>
<PRE>
</PRE>
<H3>On Exit,</H3>
<PRE>
</PRE>
<DL>
<DT>returns YES
<DD> Success in opening document
<DT>NO
<DD> Failure
</DL>
<PRE>extern BOOL HTLoadAbsolute PARAMS((CONST char * addr,
HTRequest * request));
</PRE>
<H2>Load a document from absolute name
to a stream</H2>
<H3>On Entry,</H3>
<DL>
<DT>addr
<DD> The absolute address of the
document to be accessed.
<DT>filter
<DD> if YES, treat document as
HTML
<DT>request->anchor
<DD> not filled in yet
</DL>
<H3>On Exit,</H3>
<DL>
<DT>returns YES
<DD> Success in opening document
<DT>NO
<DD> Failure
</DL>
Note: This is equivalent to HTLoadDocument
<PRE>extern BOOL HTLoadToStream PARAMS((
CONST char * addr,
BOOL filter,
HTRequest * request));
</PRE>
<H2>Load if necessary, and select an
anchor</H2>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.
<H3>On Entry,</H3>
<DL>
<DT>anchor
<DD> may be a child or parenet
anchor or 0 in which case there is
no effect.
<DT>request->anchor
<DD> Not set
yet.
</DL>
<H3>On Exit,</H3>
<PRE>
</PRE>
<DL>
<DT>returns YES
<DD> Success
<DT>returns NO
<DD> Failure
<DT>request->anchor
<DD> The parenet anchor.
</DL>
<PRE>
extern BOOL HTLoadAnchor PARAMS((HTAnchor * a,
HTRequest * request));
extern BOOL HTLoadAnchorRecursive PARAMS((HTAnchor * a,
HTRequest * request));
</PRE>
<H2>Load a Document</H2>
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).
<H3>On entry,</H3>
<DL>
<DT> request->
<DD>
<DL>
<DT> anchor <DD> a parent anchor with fully qualified
hypertext reference as its address set
<DT> output_format <DD> valid
<DT> output_stream <DD> valid on NULL
</DL>
<DT> keep_error_stack
<DD> If this is set to YES then the error (or info) stack is not cleared from
the previous call.
</DL>
<H3>On exit,</H3>
returns
<DL>
<DT> <0 <DD> Error has occured.
<DT> HT_LOADED <DD> Success
<DT> HT_NO_DATA <DD> Success, but no document loaded.
(telnet sesssion started etc)
</DL>
<PRE>
PUBLIC int HTLoad PARAMS((HTRequest * request, BOOL keep_error_stack));
</PRE>
<H2>Bind an anchor to a request structure
without loading</H2>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
<H3>On Entry,</H3>
<DL>
<DT>anchor
<DD> may be a child or parenet
anchor or 0 in which case there is
no effect.
<DT>request->anchor
<DD> Not set yet.
</DL>
<H3>On Exit,</H3>
<PRE>
</PRE>returns YES Success<P>
returns NO Failure <P>
request->anchor The parenet anchor.
<PRE>
extern BOOL HTBindAnchor PARAMS((HTAnchor *anchor, HTRequest *request));
</PRE>
<H2>Make a stream for Saving object back</H2>
<H3>On Entry,</H3>
<DL>
<DT>request->anchor
<DD> is valid anchor which
has previously beeing loaded
</DL>
<H3>On exit,</H3>
<DL>
<DT>returns
<DD> 0 if error else a stream
to save the object to.
</DL>
<PRE>
extern HTStream * HTSaveStream PARAMS((HTRequest * request));
</PRE>
<H2>Search</H2>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.
<H3>On Entry,</H3>
<DL>
<DT>*keywords
<DD> space-separated keyword
list or similar search list
<DT>here
<DD> The anchor of the object being
searched
</DL>
<PRE>extern BOOL HTSearch PARAMS((
CONST char * keywords,
HTParentAnchor* here,
HTRequest * request));
</PRE>
<H2>Search Given Indexname</H2>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.
<H3>On Entry,</H3>
<DL>
<DT>*keywords
<DD> space-separated keyword
list or similar search list
<DT>*indexname
<DD> is name of object search
is to be done on.
</DL>
<PRE>extern BOOL HTSearchAbsolute PARAMS((
CONST char * keywords,
CONST char * indexname,
HTRequest * request));
</PRE>
<H2>Register an access method</H2>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.<P>
Each of these routine takes as a
parameter a <A
NAME="z2" HREF="#z1">request structure</A> containing
details ofthe request. When the
protocol class routine is called,
the anchor elemnt in the request
is already valid (made valid by HTAccess).
<PRE>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));
</PRE>
<H2>Generate the anchor for the home
page</H2>
<PRE>
</PRE>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.
<PRE>
extern HTParentAnchor * HTHomeAnchor NOPARAMS;
</PRE>
<PRE>
#endif /* HTACCESS_H */
</PRE>
end of HTAccess
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