We had the original name lingering on for the Autotools packaging process, but that is gone since.pull/3/head
Christian Beier
6 years ago
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f997b5a75f
commit
af2448218c
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[](https://travis-ci.org/LibVNC/libvncserver) [](https://ci.appveyor.com/project/bk138/libvncserver/branch/master)
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LibVNCServer: A library for easy implementation of a VNC server.
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Copyright (C) 2001-2003 Johannes E. Schindelin
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If you already used LibVNCServer, you probably want to read NEWS.
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What is it?
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===========
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VNC is a set of programs using the RFB (Remote Frame Buffer) protocol. They
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are designed to "export" a frame buffer via net (if you don't know VNC, I
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suggest you read "Basics" below). It is already in wide use for
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administration, but it is not that easy to program a server yourself.
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This has been changed by LibVNCServer.
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There are two examples included:
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- example, a shared scribble sheet
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- pnmshow, a program to show PNMs (pictures) over the net.
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The examples are not too well documented, but easy straight forward and a
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good starting point.
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Try example: it outputs on which port it listens (default: 5900), so it is
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display 0. To view, call
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`vncviewer :0`
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You should see a sheet with a gradient and "Hello World!" written on it. Try
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to paint something. Note that every time you click, there is some bigger blot,
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whereas when you drag the mouse while clicked you draw a line. The size of the
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blot depends on the mouse button you click. Open a second vncviewer with
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the same parameters and watch it as you paint in the other window. This also
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works over internet. You just have to know either the name or the IP of your
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machine. Then it is
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`vncviewer machine.where.example.runs.com:0`
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or similar for the remote client. Now you are ready to type something. Be sure
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that your mouse sits still, because every time the mouse moves, the cursor is
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reset to the position of the pointer! If you are done with that demo, press
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the down or up arrows. If your viewer supports it, then the dimensions of the
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sheet change. Just press Escape in the viewer. Note that the server still
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runs, even if you closed both windows. When you reconnect now, everything you
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painted and wrote is still there. You can press "Page Up" for a blank page.
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The demo pnmshow is much simpler: you either provide a filename as argument
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or pipe a file through stdin. Note that the file has to be a raw pnm/ppm file,
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i.e. a truecolour graphics. Only the Escape key is implemented. This may be
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the best starting point if you want to learn how to use LibVNCServer. You
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are confronted with the fact that the bytes per pixel can only be 8, 16 or 32.
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If you want to build a VNC client instead, please have a look at the [various
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client examples](./client_examples).
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Projects using it
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=================
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VNC for KDE
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http://www.tjansen.de/krfb
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GemsVNC
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http://www.elilabs.com/~rj/gemsvnc/
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VNC for Netware
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http://forge.novell.com/modules/xfmod/project/?vncnw
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RDesktop
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http://rdesktop.sourceforge.net
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VNCpp
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https://github.com/ocrespo/VNCpp
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VirtualBox
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https://www.virtualbox.org/
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Veyon
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https://veyon.io
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Mail me, if your application is missing!
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How to build
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============
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LibVNCServer uses CMake, so you can build via:
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mkdir build
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cd build
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cmake ..
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cmake --build .
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For some more comprehensive examples that include installation of dependencies, see
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the [Unix CI](.travis.yml) and [Windows CI](.appveyor.yml) build setups.
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Crosscompiling involves some more advanced command line switches but is easily possible
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as well.
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For instance, building for Android (see https://developer.android.com/ndk/guides/cmake.html as a reference):
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mkdir build
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cd build
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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
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cmake --build .
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How to use
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==========
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To make a server, you just have to initialise a server structure using the
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function rfbDefaultScreenInit, like
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rfbScreenInfoPtr rfbScreen =
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rfbGetScreen(argc,argv,width,height,8,3,bpp);
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where byte per pixel should be 1, 2 or 4. If performance doesn't matter,
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you may try bpp=3 (internally one cannot use native data types in this
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case; if you want to use this, look at pnmshow24).
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You then can set hooks and io functions (see below) or other
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options (see below).
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And you allocate the frame buffer like this:
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rfbScreen->frameBuffer = (char*)malloc(width*height*bpp);
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After that, you initialize the server, like
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rfbInitServer(rfbScreen);
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You can use a blocking event loop, a background (pthread based) event loop,
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or implement your own using the rfbProcessEvents function.
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Making it interactive
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---------------------
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Input is handled by IO functions (see below).
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Whenever you change something in the frame buffer, call rfbMarkRectAsModified.
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Utility functions
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-----------------
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Whenever you draw something, you have to call
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rfbMarkRectAsModified(screen,x1,y1,x2,y2).
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This tells LibVNCServer to send updates to all connected clients.
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Before you draw something, be sure to call
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rfbUndrawCursor(screen).
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This tells LibVNCServer to hide the cursor.
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Remark: There are vncviewers out there, which know a cursor encoding, so
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that network traffic is low, and also the cursor doesn't need to be
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drawn the cursor every time an update is sent. LibVNCServer handles
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all the details. Just set the cursor and don't bother any more.
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To set the mouse coordinates (or emulate mouse clicks), call
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rfbDefaultPtrAddEvent(buttonMask,x,y,cl);
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IMPORTANT: do this at the end of your function, because this actually draws
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the cursor if no cursor encoding is active.
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What is the difference between rfbScreenInfoPtr and rfbClientPtr?
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-----------------------------------------------------------------
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The rfbScreenInfoPtr is a pointer to a rfbScreenInfo structure, which
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holds information about the server, like pixel format, io functions,
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frame buffer etc.
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The rfbClientPtr is a pointer to an rfbClientRec structure, which holds
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information about a client, like pixel format, socket of the
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connection, etc.
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A server can have several clients, but needn't have any. So, if you
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have a server and three clients are connected, you have one instance
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of a rfbScreenInfo and three instances of rfbClientRec's.
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The rfbClientRec structure holds a member
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rfbScreenInfoPtr screen
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which points to the server and a member
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rfbClientPtr next
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to the next client.
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The rfbScreenInfo structure holds a member
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rfbClientPtr rfbClientHead
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which points to the first client.
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So, to access the server from the client structure, you use client->screen.
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To access all clients from a server, get screen->rfbClientHead and
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iterate using client->next.
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If you change client settings, be sure to use the provided iterator
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rfbGetClientIterator(rfbScreen)
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with
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rfbClientIteratorNext(iterator)
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and
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rfbReleaseClientIterator
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to prevent thread clashes.
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Other options
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-------------
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These options have to be set between rfbGetScreen and rfbInitServer.
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If you already have a socket to talk to, just set rfbScreen->inetdSock
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(originally this is for inetd handling, but why not use it for your purpose?).
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To also start an HTTP server (running on port 5800+display_number), you have
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to set rfbScreen->httpdDir to a directory containing vncviewer.jar and
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index.vnc (like the included "webclients" directory).
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Hooks and IO functions
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----------------------
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There exist the following IO functions as members of rfbScreen:
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kbdAddEvent, kbdReleaseAllKeys, ptrAddEvent and setXCutText
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kbdAddEvent(rfbBool down,rfbKeySym key,rfbClientPtr cl)
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is called when a key is pressed.
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kbdReleaseAllKeys(rfbClientPtr cl)
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is not called at all (maybe in the future).
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ptrAddEvent(int buttonMask,int x,int y,rfbClientPtr cl)
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is called when the mouse moves or a button is pressed.
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WARNING: if you want to have proper cursor handling, call
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rfbDefaultPtrAddEvent(buttonMask,x,y,cl)
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in your own function. This sets the coordinates of the cursor.
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setXCutText(char* str,int len,rfbClientPtr cl)
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is called when the selection changes.
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There are only two hooks:
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newClientHook(rfbClientPtr cl)
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is called when a new client has connected.
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displayHook
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is called just before a frame buffer update is sent.
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You can also override the following methods:
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getCursorPtr(rfbClientPtr cl)
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This could be used to make an animated cursor (if you really want ...)
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setTranslateFunction(rfbClientPtr cl)
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If you insist on colour maps or something more obscure, you have to
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implement this. Default is a trueColour mapping.
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Cursor handling
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---------------
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The screen holds a pointer
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rfbCursorPtr cursor
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to the current cursor. Whenever you set it, remember that any dynamically
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created cursor (like return value from rfbMakeXCursor) is not free'd!
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The rfbCursor structure consists mainly of a mask and a source. The mask
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describes, which pixels are drawn for the cursor (a cursor needn't be
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rectangular). The source describes, which colour those pixels should have.
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The standard is an XCursor: a cursor with a foreground and a background
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colour (stored in backRed,backGreen,backBlue and the same for foreground
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in a range from 0-0xffff). Therefore, the arrays "mask" and "source"
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contain pixels as single bits stored in bytes in MSB order. The rows are
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padded, such that each row begins with a new byte (i.e. a 10x4
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cursor's mask has 2x4 bytes, because 2 bytes are needed to hold 10 bits).
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It is however very easy to make a cursor like this:
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char* cur=" "
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" xx "
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" x "
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" ";
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char* mask="xxxx"
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"xxxx"
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"xxxx"
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"xxx ";
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rfbCursorPtr c=rfbMakeXCursor(4,4,cur,mask);
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You can even set "mask" to NULL in this call and LibVNCServer will calculate
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a mask for you (dynamically, so you have to free it yourself).
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There is also an array named "richSource" for colourful cursors. They have
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the same format as the frameBuffer (i.e. if the server is 32 bit,
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a 10x4 cursor has 4x10x4 bytes).
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History
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=======
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LibVNCServer is based on Tridia VNC and OSXvnc, which in turn are based on
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the original code from ORL/AT&T.
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When I began hacking with computers, my first interest was speed. So, when I
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got around assembler, I programmed the floppy to do much of the work, because
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its clock rate was higher than that of my C64. This was my first experience
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with client/server techniques.
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When I came around Xwindows (much later), I was at once intrigued by the
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elegance of such connectedness between the different computers. I used it
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a lot - not the least priority lay on games. However, when I tried it over
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modem from home, it was no longer that much fun.
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When I started working with ASP (Application Service Provider) programs, I
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tumbled across Tarantella and Citrix. Being a security fanatic, the idea of
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running a server on windows didn't appeal to me, so Citrix went down the
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basket. However, Tarantella has its own problems (security as well as the
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high price). But at the same time somebody told me about this "great little
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administrator's tool" named VNC. Being used to windows programs' sizes, the
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surprise was reciprocal inverse to the size of VNC!
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At the same time, the program "rdesktop" (a native Linux client for the
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Terminal Services of Windows servers) came to my attention. There where even
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works under way to make a protocol converter "rdp2vnc" out of this. However,
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my primary goal was a slow connection and rdp2vnc could only speak RRE
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encoding, which is not that funny with just 5kB/s. Tim Edmonds, the original
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author of rdp2vnc, suggested that I adapt it to Hextile Encoding, which is
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better. I first tried that, but had no success at all (crunchy pictures).
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Also, I liked the idea of an HTTP server included and possibly other
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encodings like the Tight Encodings from Const Kaplinsky. So I started looking
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for libraries implementing a VNC server where I could steal what I can't make.
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I found some programs based on the demo server from AT&T, which was also the
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basis for rdp2vnc (can only speak Raw and RRE encoding). There were some
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rumors that GGI has a VNC backend, but I didn't find any code, so probably
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there wasn't a working version anyway.
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All of a sudden, everything changed: I read on freshmeat that "OSXvnc" was
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released. I looked at the code and it was not much of a problem to work out
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a simple server - using every functionality there is in Xvnc. It became clear
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to me that I *had* to build a library out of it, so everybody can use it.
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Every change, every new feature can propagate to every user of it.
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It also makes everything easier:
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You don't care about the cursor, once set (or use the standard cursor).
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You don't care about those sockets. You don't care about encodings.
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You just change your frame buffer and inform the library about it. Every once
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in a while you call rfbProcessEvents and that's it.
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Basics
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======
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VNC (Virtual network computing) works like this: You set up a server and can
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connect to it via vncviewers. The communication uses a protocol named RFB
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(Remote Frame Buffer). If the server supports HTTP, you can also connect
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using a java enabled browser. In this case, the server sends back a
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vncviewer applet with the correct settings.
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There exist several encodings for VNC, which are used to compress the regions
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which have changed before they are sent to the client. A client need not be
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able to understand every encoding, but at least Raw encoding. Which encoding
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it understands is negotiated by the RFB protocol.
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The following encodings are known to me:
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Raw, RRE, CoRRE, Hextile, CopyRect from the original AT&T code and
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Tight, ZLib, LastRect, XCursor, RichCursor from Const Kaplinsky et al.
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If you are using a modem, you want to try the "new" encodings. Especially
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with my 56k modem I like ZLib or Tight with Quality 0. In my tests, it even
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beats Tarantella.
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There is the possibility to set a password, which is also negotiated by the
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RFB protocol, but IT IS NOT SECURE. Anybody sniffing your net can get the
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password. You really should tunnel through SSH.
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Windows or: why do you do that to me?
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=====================================
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If you love products from Redmod, you better skip this paragraph.
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I am always amazed how people react whenever Microsoft(tm) puts in some
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features into their products which were around for a long time. Especially
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reporters seem to not know dick about what they are reporting about! But
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what is every time annoying again, is that they don't do it right. Every
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concept has its new name (remember what enumerators used to be until
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Mickeysoft(tm) claimed that enumerators are what we thought were iterators.
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Yeah right, enumerators are also containers. They are not separated. Muddy.)
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There are three packages you want to get hold of: zlib, jpeg and pthreads.
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The latter is not strictly necessary, but when you put something like this
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into your source:
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```
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#define MUTEX(s)
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struct {
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int something;
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MUTEX(latex);
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}
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```
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Microsoft's C++ compiler doesn't do it. It complains that this is an error.
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This, however, is how I implemented mutexes in case you don't need pthreads,
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and so don't need the mutex.
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You can find the packages at
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http://www.gimp.org/win32/extralibs-dev-20001007.zip
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Thanks go to all the GIMP team!
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What are those other targets in the Makefile?
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=============================================
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OSXvnc-server is the original OSXvnc adapted to use the library, which was in
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turn adapted from OSXvnc. As you easily can see, the OSX dependend part is
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minimal.
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storepasswd is the original program to save a vnc style password in a file.
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Unfortunately, authentication as every vncviewer speaks it means the server
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has to know the plain password. You really should tunnel via ssh or use
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your own PasswordCheck to build a PIN/TAN system.
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sratest is a test unit. Run it to assert correct behaviour of sraRegion. I
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wrote this to test my iterator implementation.
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blooptest is a test of pthreads. It is just the example, but with a background
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loop to hunt down thread lockups.
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pnmshow24 is like pnmshow, but it uses 3 bytes/pixel internally, which is not
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as efficient as 4 bytes/pixel for translation, because there is no native data
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type of that size, so you have to memcpy pixels and be real cautious with
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endianness. Anyway, it works.
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fontsel is a test for rfbSelectBox and rfbLoadConsoleFont. If you have Linux
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console fonts, you can browse them via VNC. Directory browsing not implemented
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yet :-(
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Why I don't feel bad about GPL
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==============================
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At the beginning of this projects I would have liked to make it a BSD
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license. However, it is based on plenty of GPL'ed code, so it has to be
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a GPL. I hear BeeGee complaining: "but that's invasive, every derivative
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work, even just linking, makes my software GPL!"
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Yeah. That's right. It is because there are nasty jarheads out there who
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would take anybody's work and claim it their own, selling it for much too
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much money, stealing freedom and innovation from others, saying they were
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the maintainers of innovation, lying, making money with that.
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The people at AT&T worked really well to produce something as clean and lean
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as VNC. The managers decided that for their fame, they would release the
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program for free. But not only that! They realized that by releasing also
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the code for free, VNC would become an evolving little child, conquering
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new worlds, making its parents very proud. As well they can be! To protect
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this innovation, they decided to make it GPL, not BSD. The principal
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difference is: You can make closed source programs deriving from BSD, not
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from GPL. You have to give proper credit with both.
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Now, why not BSD? Well, imagine your child being some famous actor. Along
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comes a manager who exploits your child exclusively, that is: nobody else
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can profit from the child, it itself included. Got it?
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What reason do you have now to use this library commercially?
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Several: You don't have to give away your product. Then you have effectively
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circumvented the GPL, because you have the benefits of other's work and you
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don't give back anything and you will be in hell for that. In fact, this
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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
|
||||
|
||||
@ -0,0 +1,476 @@
|
||||
[](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
|
||||
|
||||
Loading…
Reference in new issue