+++ /dev/null
-LibVNCServer: a library for easy implementation of a RDP/VNC server.
-Copyright (C) 2001-2003 Johannes E. Schindelin
-
-If you already used LibVNCServer, you probably want to read NEWS.
-
-What is it?
------------
-
-VNC is a set of programs using the RFB (Remote Frame Buffer) protocol. They
-are designed to "export" a frame buffer via net (if you don't know VNC, I
-suggest you read "Basics" below). It is already in wide use for
-administration, but it is not that easy to program a server yourself.
-
-This has been changed by LibVNCServer.
-
-There are two examples included:
- - example, a shared scribble sheet
- - pnmshow, a program to show PNMs (pictures) over the net.
-
-The examples are not too well documented, but easy straight forward and a
-good starting point.
-
-Try example: it outputs on which port it listens (default: 5900), so it is
-display 0. To view, call
- vncviewer :0
-You should see a sheet with a gradient and "Hello World!" written on it. Try
-to paint something. Note that everytime you click, there is some bigger blot,
-whereas when you drag the mouse while clicked you draw a line. The size of the
-blot depends on the mouse button you click. Open a second vncviewer with
-the same parameters and watch it as you paint in the other window. This also
-works over internet. You just have to know either the name or the IP of your
-machine. Then it is
- vncviewer machine.where.example.runs.com:0
-or similar for the remote client. Now you are ready to type something. Be sure
-that your mouse sits still, because everytime the mouse moves, the cursor is
-reset to the position of the pointer! If you are done with that demo, press
-the down or up arrows. If your viewer supports it, then the dimensions of the
-sheet change. Just press Escape in the viewer. Note that the server still
-runs, even if you closed both windows. When you reconnect now, everything you
-painted and wrote is still there. You can press "Page Up" for a blank page.
-
-The demo pnmshow is much simpler: you either provide a filename as argument
-or pipe a file through stdin. Note that the file has to be a raw pnm/ppm file,
-i.e. a truecolour graphics. Only the Escape key is implemented. This may be
-the best starting point if you want to learn how to use LibVNCServer. You
-are confronted with the fact that the bytes per pixel can only be 8, 16 or 32.
-
-Projects using it
-----------------------------------------
-
-VNC for KDE
-http://www.tjansen.de/krfb
-
-GemsVNC
-http://www.elilabs.com/~rj/gemsvnc/
-
-VNC for Netware
-http://forge.novell.com/modules/xfmod/project/?vncnw
-
-RDesktop
-http://rdesktop.sourceforge.net
-
-Mail me, if your application is missing!
-
-How to use
-----------
-
-To make a server, you just have to initialise a server structure using the
-function rfbDefaultScreenInit, like
- rfbScreenInfoPtr rfbScreen =
- rfbGetScreen(argc,argv,width,height,8,3,bpp);
-where byte per pixel should be 1, 2 or 4. If performance doesn't matter,
-you may try bpp=3 (internally one cannot use native data types in this
-case; if you want to use this, look at pnmshow24).
-
-
-You then can set hooks and io functions (see below) or other
-options (see below).
-
-And you allocate the frame buffer like this:
- rfbScreen->frameBuffer = (char*)malloc(width*height*bpp);
-
-After that, you initialize the server, like
- rfbInitServer(rfbScreen);
-
-You can use a blocking event loop, a background (pthread based) event loop,
-or implement your own using the rfbProcessEvents function.
-
-Making it interactive
----------------------
-
-Input is handled by IO functions (see below).
-
-Whenever you change something in the frame buffer, call rfbMarkRectAsModified.
-You should make sure that the cursor is not drawn before drawing yourself
-by calling rfbUndrawCursor. You can also draw the cursor using rfbDrawCursor,
-but it hardly seems necessary. For cursor details, see below.
-
-Utility functions
------------------
-
-Whenever you draw something, you have to call
- rfbMarkRectAsModified(screen,x1,y1,x2,y2).
-This tells LibVNCServer to send updates to all connected clients.
-
-Before you draw something, be sure to call
- rfbUndrawCursor(screen).
-This tells LibVNCServer to hide the cursor.
-Remark: There are vncviewers out there, which know a cursor encoding, so
-that network traffic is low, and also the cursor doesn't need to be
-drawn the cursor everytime an update is sent. LibVNCServer handles
-all the details. Just set the cursor and don't bother any more.
-
-To set the mouse coordinates (or emulate mouse clicks), call
- defaultPtrAddEvent(buttonMask,x,y,cl);
-IMPORTANT: do this at the end of your function, because this actually draws
-the cursor if no cursor encoding is active.
-
-What is the difference between rfbScreenInfoPtr and rfbClientPtr?
------------------------------------------------------------------
-
-The rfbScreenInfoPtr is a pointer to a rfbScreenInfo structure, which
-holds information about the server, like pixel format, io functions,
-frame buffer etc.
-
-The rfbClientPtr is a pointer to an rfbClientRec structure, which holds
-information about a client, like pixel format, socket of the
-connection, etc.
-
-A server can have several clients, but needn't have any. So, if you
-have a server and three clients are connected, you have one instance
-of a rfbScreenInfo and three instances of rfbClientRec's.
-
-The rfbClientRec structure holds a member
- rfbScreenInfoPtr screen
-which points to the server and a member
- rfbClientPtr next
-to the next client.
-
-The rfbScreenInfo structure holds a member
- rfbClientPtr rfbClientHead
-which points to the first client.
-
-So, to access the server from the client structure, you use client->screen.
-To access all clients from a server, get screen->rfbClientHead and
-iterate using client->next.
-
-If you change client settings, be sure to use the provided iterator
- rfbGetClientIterator(rfbScreen)
-with
- rfbClientIteratorNext(iterator)
-and
- rfbReleaseClientIterator
-to prevent thread clashes.
-
-Other options
--------------
-
-These options have to be set between rfbGetScreen and rfbInitServer.
-
-If you already have a socket to talk to, just set rfbScreen->inetdSock
-(originally this is for inetd handling, but why not use it for your purpose?).
-
-To also start an HTTP server (running on port 5800+display_number), you have
-to set rfbScreen->httpdDir to a directory containing vncviewer.jar and
-index.vnc (like the included "classes" directory).
-
-Hooks and IO functions
-----------------------
-
-There exist the following IO functions as members of rfbScreen:
-kbdAddEvent, kbdReleaseAllKeys, ptrAddEvent and setXCutText
-
-kbdAddEvent(rfbBool down,rfbKeySym key,rfbClientPtr cl)
- is called when a key is pressed.
-kbdReleaseAllKeys(rfbClientPtr cl)
- is not called at all (maybe in the future).
-ptrAddEvent(int buttonMask,int x,int y,rfbClientPtr cl)
- is called when the mouse moves or a button is pressed.
- WARNING: if you want to have proper cursor handling, call
- defaultPtrAddEvent(buttonMask,x,y,cl)
- in your own function. This sets the coordinates of the cursor.
-setXCutText(char* str,int len,rfbClientPtr cl)
- is called when the selection changes.
-
-There are only two hooks:
-newClientHook(rfbClientPtr cl)
- is called when a new client has connected.
-displayHook
- is called just before a frame buffer update is sent.
-
-You can also override the following methods:
-getCursorPtr(rfbClientPtr cl)
- This could be used to make an animated cursor (if you really want ...)
-setTranslateFunction(rfbClientPtr cl)
- If you insist on colour maps or something more obscure, you have to
- implement this. Default is a trueColour mapping.
-
-Cursor handling
----------------
-
-The screen holds a pointer
- rfbCursorPtr cursor
-to the current cursor. Whenever you set it, remember that any dynamically
-created cursor (like return value from rfbMakeXCursor) is not free'd!
-
-The rfbCursor structure consists mainly of a mask and a source. The mask
-describes, which pixels are drawn for the cursor (a cursor needn't be
-rectangular). The source describes, which colour those pixels should have.
-
-The standard is an XCursor: a cursor with a foreground and a background
-colour (stored in backRed,backGreen,backBlue and the same for foreground
-in a range from 0-0xffff). Therefore, the arrays "mask" and "source"
-contain pixels as single bits stored in bytes in MSB order. The rows are
-padded, such that each row begins with a new byte (i.e. a 10x4
-cursor's mask has 2x4 bytes, because 2 bytes are needed to hold 10 bits).
-
-It is however very easy to make a cursor like this:
-
-char* cur=" "
- " xx "
- " x "
- " ";
-char* mask="xxxx"
- "xxxx"
- "xxxx"
- "xxx ";
-rfbCursorPtr c=rfbMakeXCursor(4,4,cur,mask);
-
-You can even set "mask" to NULL in this call and LibVNCServer will calculate
-a mask for you (dynamically, so you have to free it yourself).
-
-There is also an array named "richSource" for colourful cursors. They have
-the same format as the frameBuffer (i.e. if the server is 32 bit,
-a 10x4 cursor has 4x10x4 bytes).
-
-History
--------
-
-LibVNCServer is based on Tridia VNC and OSXvnc, which in turn are based on
-the original code from ORL/AT&T.
-
-When I began hacking with computers, my first interest was speed. So, when I
-got around assembler, I programmed the floppy to do much of the work, because
-it's clock rate was higher than that of my C64. This was my first experience
-with client/server techniques.
-
-When I came around Xwindows (much later), I was at once intrigued by the
-elegance of such connectedness between the different computers. I used it
-a lot - not the least priority lay on games. However, when I tried it over
-modem from home, it was no longer that much fun.
-
-When I started working with ASP (Application Service Provider) programs, I
-tumbled across Tarantella and Citrix. Being a security fanatic, the idea of
-running a server on windows didn't appeal to me, so Citrix went down the
-basket. However, Tarantella has it's own problems (security as well as the
-high price). But at the same time somebody told me about this "great little
-administrator's tool" named VNC. Being used to windows programs' sizes, the
-surprise was reciprocal inverse to the size of VNC!
-
-At the same time, the program "rdesktop" (a native Linux client for the
-Terminal Services of Windows servers) came to my attention. There where even
-works under way to make a protocol converter "rdp2vnc" out of this. However,
-my primary goal was a slow connection and rdp2vnc could only speak RRE
-encoding, which is not that funny with just 5kB/s. Tim Edmonds, the original
-author of rdp2vnc, suggested that I adapt it to Hextile Encoding, which is
-better. I first tried that, but had no success at all (crunchy pictures).
-
-Also, I liked the idea of an HTTP server included and possibly other
-encodings like the Tight Encodings from Const Kaplinsky. So I started looking
-for libraries implementing a VNC server where I could steal what I can't make.
-I found some programs based on the demo server from AT&T, which was also the
-basis for rdp2vnc (can only speak Raw and RRE encoding). There were some
-rumors that GGI has a VNC backend, but I didn't find any code, so probably
-there wasn't a working version anyway.
-
-All of a sudden, everything changed: I read on freshmeat that "OSXvnc" was
-released. I looked at the code and it was not much of a problem to work out
-a simple server - using every functionality there is in Xvnc. It became clear
-to me that I *had* to build a library out of it, so everybody can use it.
-Every change, every new feature can propagate to every user of it.
-
-It also makes everything easier:
- You don't care about the cursor, once set (or use the standard cursor).
-You don't care about those sockets. You don't care about encodings.
-You just change your frame buffer and inform the library about it. Every once
-in a while you call rfbProcessEvents and that's it.
-
-Basics
-------
-
-VNC (Virtual network computing) works like this: You set up a server and can
-connect to it via vncviewers. The communication uses a protocol named RFB
-(Remote Frame Buffer). If the server supports HTTP, you can also connect
-using a java enabled browser. In this case, the server sends back a
-vncviewer applet with the correct settings.
-
-There exist several encodings for VNC, which are used to compress the regions
-which have changed before they are sent to the client. A client need not be
-able to understand every encoding, but at least Raw encoding. Which encoding
-it understands is negotiated by the RFB protocol.
-
-The following encodings are known to me:
-Raw, RRE, CoRRE, Hextile, CopyRect from the original AT&T code and
-Tight, ZLib, LastRect, XCursor, RichCursor from Const Kaplinsky et al.
-
-If you are using a modem, you want to try the "new" encodings. Especially
-with my 56k modem I like ZLib or Tight with Quality 0. In my tests, it even
-beats Tarantella.
-
-There is the possibility to set a password, which is also negotiated by the
-RFB protocol, but IT IS NOT SECURE. Anybody sniffing your net can get the
-password. You really should tunnel through SSH.
-
-Windows or: why do you do that to me?
---------------------------------------------
-
-If you love products from Redmod, you better skip this paragraph.
-I am always amazed how people react whenever Microsoft(tm) puts in some
-features into their products which were around for a long time. Especially
-reporters seem to not know dick about what they are reporting about! But
-what is everytime annoying again, is that they don't do it right. Every
-concept has it's new name (remember what enumerators used to be until
-Mickeysoft(tm) claimed that enumerators are what we thought were iterators.
-Yeah right, enumerators are also containers. They are not separated. Muddy.)
-
-There are three packages you want to get hold of: zlib, jpeg and pthreads.
-The latter is not strictly necessary, but when you put something like this
-into your source:
-
-#define MUTEX(s)
- struct {
- int something;
- MUTEX(latex);
- }
-
-Microsoft's C++ compiler doesn't do it. It complains that this is an error.
-This, however, is how I implemented mutexes in case you don't need pthreads,
-and so don't need the mutex.
-
-You can find the packages at
-http://www.gimp.org/win32/extralibs-dev-20001007.zip
-
-Thanks go to all the GIMP team!
-
-What are those other targets in the Makefile?
----------------------------------------------
-
-OSXvnc-server is the original OSXvnc adapted to use the library, which was in
-turn adapted from OSXvnc. As you easily can see, the OSX dependend part is
-minimal.
-
-storepasswd is the original program to save a vnc style password in a file.
-Unfortunately, authentication as every vncviewer speaks it means the server
-has to know the plain password. You really should tunnel via ssh or use
-your own PasswordCheck to build a PIN/TAN system.
-
-sratest is a test unit. Run it to assert correct behaviour of sraRegion. I
-wrote this to test my iterator implementation.
-
-blooptest is a test of pthreads. It is just the example, but with a background
-loop to hunt down thread lockups.
-
-pnmshow24 is like pnmshow, but it uses 3 bytes/pixel internally, which is not
-as efficient as 4 bytes/pixel for translation, because there is no native data
-type of that size, so you have to memcpy pixels and be real cautious with
-endianness. Anyway, it works.
-
-fontsel is a test for rfbSelectBox and rfbLoadConsoleFont. If you have Linux
-console fonts, you can browse them via VNC. Directory browsing not implemented
-yet :-(
-
-Why I don't feel bad about GPL
-------------------------------
-
-At the beginning of this projects I would have liked to make it a BSD
-license. However, it is based on plenty of GPL'ed code, so it has to be
-a GPL. I hear BeeGee complaining: "but that's invasive, every derivative
-work, even just linking, makes my software GPL!"
-
-Yeah. That's right. It is because there are nasty jarheads out there who
-would take anybody's work and claim it their own, selling it for much too
-much money, stealing freedom and innovation from others, saying they were
-the maintainers of innovation, lying, making money with that.
-
-The people at AT&T worked really well to produce something as clean and lean
-as VNC. The managers decided that for their fame, they would release the
-program for free. But not only that! They realized that by releasing also
-the code for free, VNC would become an evolving little child, conquering
-new worlds, making it's parents very proud. As well they can be! To protect
-this innovation, they decided to make it GPL, not BSD. The principal
-difference is: You can make closed source programs deriving from BSD, not
-from GPL. You have to give proper credit with both.
-
-Now, why not BSD? Well, imagine your child being some famous actor. Along
-comes a manager who exploits your child exclusively, that is: nobody else
-can profit from the child, it itself included. Got it?
-
-What reason do you have now to use this library commercially?
-
-Several: You don't have to give away your product. Then you have effectively
-circumvented the GPL, because you have the benefits of other's work and you
-don't give back anything and you will be in hell for that. In fact, this
-library, as my other projects, is a payback for all the free software I can
-use (and sometimes, make better). For example, just now, I am using XEmacs
-on top of XFree86, all running under Linux.
-
-Better: Use a concept like MySQL. This is free software, however, they make
-money with it. If you want something implemented, you have the choice:
-Ask them to do it (and pay a fair price), or do it yourself, normally giving
-back your enhancements to the free world of computing.
-
-Learn from it: If you like the style this is written, learn how to imitate
-it. If you don't like the style, learn how to avoid those things you don't
-like. I learnt so much, just from looking at code like Linux, XEmacs,
-LilyPond, STL, etc.
-
-License
--------
-
-This program is free software; you can redistribute it and/or
-modify it under the terms of the GNU General Public License
-as published by the Free Software Foundation; either version 2
-of the License, or (at your option) any later version.
-
-This program is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License
-along with this program; if not, write to the Free Software
-Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.dfdf
-
-Contact
--------
-
-To contact me, mail me: Johannes dot Schindelin at gmx dot de
-
projects / presencevnc / blobdiff