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@@ -1,476 +0,0 @@ -[](https://travis-ci.org/LibVNC/libvncserver) [](https://ci.appveyor.com/project/bk138/libvncserver/branch/master) - -LibVNCServer: A library for easy implementation of a 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 every time 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 every time 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. - -If you want to build a VNC client instead, please have a look at the [various -client examples](./client_examples). - -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 - -VNCpp -https://github.com/ocrespo/VNCpp - -VirtualBox -https://www.virtualbox.org/ - -Veyon -https://veyon.io - -Mail me, if your application is missing! - -How to build -============ - -LibVNCServer uses CMake, so you can build via: - - mkdir build - cd build - cmake .. - cmake --build . - -For some more comprehensive examples that include installation of dependencies, see -the [Unix CI](.travis.yml) and [Windows CI](.appveyor.yml) build setups. - -Crosscompiling involves some more advanced command line switches but is easily possible -as well. - -For instance, building for Android (see https://developer.android.com/ndk/guides/cmake.html as a reference): - - mkdir build - cd build - cmake .. -DANDROID_NDK=<path> -DCMAKE_TOOLCHAIN_FILE=<path> -DANDROID_NATIVE_API_LEVEL=<API level you want> -DWITH_PNG=OFF # NDK not shipping png per default - cmake --build . - - -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. - -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 every time 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 - rfbDefaultPtrAddEvent(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 "webclients" 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 - rfbDefaultPtrAddEvent(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 -its 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 its 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 every time annoying again, is that they don't do it right. Every -concept has its 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 its 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 - |