add an extension mechanism for LibVNCClient, modify the client data handling

so that more than one data structure can be attached, and add an example
to speak the client part of the back channel.

client_examples/Makefile.am

@@ -23,7 +23,7 @@ SDLvncviewer_CFLAGS=$(SDL_CFLAGS)
 SDLvncviewer_LDADD=$(LDADD) $(SDL_LIBS)
 endif
 
-noinst_PROGRAMS=ppmtest $(SDLVIEWER) $(FFMPEG_CLIENT)
+noinst_PROGRAMS=ppmtest $(SDLVIEWER) $(FFMPEG_CLIENT) backchannel
 
 
 

client_examples/SDLvncviewer.c

@@ -16,7 +16,7 @@ static rfbBool resize(rfbClient* client) {
 			okay=SDL_VideoModeOK(width,height,depth,flags);
 	if(okay) {
 		SDL_Surface* sdl=SDL_SetVideoMode(width,height,depth,flags);
-		client->clientData=sdl;
+		rfbClientSetClientData(client, SDL_Init, sdl);
 		client->frameBuffer=sdl->pixels;
 		if(first || depth!=client->format.bitsPerPixel) {
 			first=FALSE;
@@ -30,7 +30,7 @@ static rfbBool resize(rfbClient* client) {
 			SetFormatAndEncodings(client);
 		}
 	} else {
-		SDL_Surface* sdl=client->clientData;
+		SDL_Surface* sdl=rfbClientGetClientData(client, SDL_Init);
 		rfbClientLog("Could not set resolution %dx%d!\n",
 				client->width,client->height);
 		if(sdl) {
@@ -188,7 +188,7 @@ static rfbKeySym SDL_keysym2rfbKeySym(int keysym) {
 }
 
 static void update(rfbClient* cl,int x,int y,int w,int h) {
-	SDL_UpdateRect(cl->clientData, x, y, w, h);
+	SDL_UpdateRect(rfbClientGetClientData(cl, SDL_Init), x, y, w, h);
 }
 
 #ifdef __MINGW32__

client_examples/backchannel.c

+/* A simple example of an RFB client */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+#include <errno.h>
+#include <rfb/rfbclient.h>
+
+static void HandleRect(rfbClient* client, int x, int y, int w, int h) {
+}
+
+/*
+ * The client part of the back channel extension example.
+ *
+ */
+
+#define rfbBackChannel 155
+
+typedef struct backChannelMsg {
+        uint8_t type;
+        uint8_t pad1;
+        uint16_t pad2;
+        uint32_t size;
+} backChannelMsg;
+
+static void sendMessage(rfbClient* client, char* text)
+{
+	backChannelMsg msg;
+	uint32_t length = strlen(text)+1;
+
+	msg.type = rfbBackChannel;
+	msg.size = rfbClientSwap32IfLE(length);
+	if(!WriteToRFBServer(client, (char*)&msg, sizeof(msg)) ||
+			!WriteToRFBServer(client, text, length)) {
+		rfbClientLog("enableBackChannel: write error (%d: %s)", errno, strerror(errno));
+	}
+}
+
+static rfbBool handleBackChannelMessage(rfbClient* client,
+	rfbServerToClientMsg* message)
+{
+	backChannelMsg msg;
+	char* text;
+
+	if(message->type != rfbBackChannel)
+		return FALSE;
+
+	rfbClientSetClientData(client, sendMessage, sendMessage);
+
+	if(!ReadFromRFBServer(client, ((char*)&msg)+1, sizeof(msg)-1))
+		return TRUE;
+	msg.size = rfbClientSwap32IfLE(msg.size);
+	text = malloc(msg.size);
+	if(!ReadFromRFBServer(client, text, msg.size)) {
+		free(text);
+		return TRUE;
+	}
+
+	rfbClientLog("got back channel message: %s\n", text);
+	free(text);
+
+	return TRUE;
+}
+
+static int backChannelEncodings[] = { rfbBackChannel, 0 };
+
+static rfbClientProtocolExtension backChannel = {
+	backChannelEncodings,		/* encodings */
+	NULL,				/* handleEncoding */
+	handleBackChannelMessage,	/* handleMessage */
+	NULL				/* next extension */
+};
+
+int
+main(int argc, char **argv)
+{
+	rfbClient* client = rfbGetClient(8,3,4);
+
+	client->GotFrameBufferUpdate = HandleRect;
+	rfbClientRegisterExtension(&backChannel);
+
+	if (!rfbInitClient(client,&argc,argv))
+		return 1;
+
+	while (1) {
+		/* After each idle second, send a message */
+		if(WaitForMessage(client,1000000)>0)
+			HandleRFBServerMessage(client);
+		else if(rfbClientGetClientData(client, sendMessage))
+			sendMessage(client, "Dear Server,\n"
+					"thank you for understanding "
+					"back channel messages!");
+	}
+
+	rfbClientCleanup(client);
+
+	return 0;
+}
+

libvncclient/rfbproto.c

@@ -77,6 +77,49 @@ rfbDefaultClientLog(const char *format, ...)
 rfbClientLogProc rfbClientLog=rfbDefaultClientLog;
 rfbClientLogProc rfbClientErr=rfbDefaultClientLog;
 
+/* extensions */
+
+rfbClientProtocolExtension* rfbClientExtensions = NULL;
+
+void rfbClientRegisterExtension(rfbClientProtocolExtension* e)
+{
+	e->next = rfbClientExtensions;
+	rfbClientExtensions = e;
+}
+
+/* client data */
+
+void rfbClientSetClientData(rfbClient* client, void* tag, void* data)
+{
+	rfbClientData* clientData = client->clientData;
+
+	while(clientData && clientData->tag != tag)
+		clientData = clientData->next;
+	if(clientData == NULL) {
+		clientData = calloc(sizeof(rfbClientData), 1);
+		clientData->next = client->clientData;
+		client->clientData = clientData;
+		clientData->tag = tag;
+	}
+
+	clientData->data = data;
+}
+
+void* rfbClientGetClientData(rfbClient* client, void* tag)
+{
+	rfbClientData* clientData = client->clientData;
+
+	while(clientData) {
+		if(clientData->tag == tag)
+			return clientData->data;
+		clientData = clientData->next;
+	}
+
+	return NULL;
+}
+
+/* messages */
+
 static void FillRectangle(rfbClient* client, int x, int y, int w, int h, uint32_t colour) {
   int i,j;
 
@@ -259,6 +302,12 @@ InitialiseRFBConnection(rfbClient* client)
     return FALSE;
   }
 
+#if rfbProtocolMinorVersion == 7
+  /* work around LibVNCClient not yet speaking RFB 3.7 */
+#undef rfbProtocolMinorVersion
+#define rfbProtocolMinorVersion 3
+#endif
+
   rfbClientLog("VNC server supports protocol version %d.%d (viewer %d.%d)\n",
 	  major, minor, rfbProtocolMajorVersion, rfbProtocolMinorVersion);
 
@@ -394,6 +443,7 @@ SetFormatAndEncodings(rfbClient* client)
   rfbBool requestCompressLevel = FALSE;
   rfbBool requestQualityLevel = FALSE;
   rfbBool requestLastRectEncoding = FALSE;
+  rfbClientProtocolExtension* e;
 
   spf.type = rfbSetPixelFormat;
   spf.format = client->format;
@@ -535,6 +585,13 @@ SetFormatAndEncodings(rfbClient* client)
     encs[se->nEncodings++] = rfbClientSwap32IfLE(rfbEncodingLastRect);
   }
 
+  for(e = rfbClientExtensions; e; e = e->next)
+    if(e->encodings) {
+      int* enc;
+      for(enc = e->encodings; *enc; enc++)
+	encs[se->nEncodings++] = rfbClientSwap32IfLE(*enc);
+    }
+
   len = sz_rfbSetEncodingsMsg + se->nEncodings * 4;
 
   se->nEncodings = rfbClientSwap16IfLE(se->nEncodings);
@@ -923,9 +980,20 @@ HandleRFBServerMessage(rfbClient* client)
 #endif
 
       default:
-	rfbClientLog("Unknown rect encoding %d\n",
-		(int)rect.encoding);
-	return FALSE;
+	 {
+	   rfbBool handled = FALSE;
+	   rfbClientProtocolExtension* e;
+
+	   for(e = rfbClientExtensions; !handled && e; e = e->next)
+	     if(e->handleEncoding && e->handleEncoding(client, &rect))
+	       handled = TRUE;
+
+	   if(!handled) {
+	     rfbClientLog("Unknown rect encoding %d\n",
+		 (int)rect.encoding);
+	     return FALSE;
+	   }
+	 }
       }
 
       /* Now we may discard "soft cursor locks". */
@@ -934,16 +1002,6 @@ HandleRFBServerMessage(rfbClient* client)
       client->GotFrameBufferUpdate(client, rect.r.x, rect.r.y, rect.r.w, rect.r.h);
     }
 
-#ifdef MITSHM
-    /* if using shared memory PutImage, make sure that the X server has
-       updated its framebuffer before we reuse the shared memory.  This is
-       mainly to avoid copyrect using invalid screen contents - not sure
-       if we'd need it otherwise. */
-
-    if (client->appData.useShm)
-      XSync(dpy, FALSE);
-#endif
-
     if (!SendIncrementalFramebufferUpdateRequest(client))
       return FALSE;
 
@@ -981,8 +1039,21 @@ HandleRFBServerMessage(rfbClient* client)
   }
 
   default:
-    rfbClientLog("Unknown message type %d from VNC server\n",msg.type);
-    return FALSE;
+    {
+      rfbBool handled = FALSE;
+      rfbClientProtocolExtension* e;
+
+      for(e = rfbClientExtensions; !handled && e; e = e->next)
+	if(e->handleMessage && e->handleMessage(client, &msg))
+	  handled = TRUE;
+
+      if(!handled) {
+	char buffer[256];
+	ReadFromRFBServer(client, buffer, 256);
+	rfbClientLog("Unknown message type %d from VNC server\n",msg.type);
+	return FALSE;
+      }
+    }
   }
 
   return TRUE;

rfb/rfbclient.h

@@ -63,6 +63,15 @@ typedef struct {
   rfbBool doNotSleep;
 } rfbVNCRec;
 
+/* client data */
+
+typedef struct rfbClientData {
+	void* tag;
+	void* data;
+	struct rfbClientData* next;
+} rfbClientData;
+
+/* app data (belongs into rfbClient?) */
 
 typedef struct {
   rfbBool shareDesktop;
@@ -181,7 +190,7 @@ typedef struct _rfbClient {
 	uint8_t *rcSource, *rcMask;
 
 	/* private data pointer */
-	void* clientData;
+	rfbClientData* clientData;
 
 	rfbVNCRec* vncRec;
 
@@ -223,6 +232,26 @@ extern rfbBool HandleRFBServerMessage(rfbClient* client);
 
 extern void PrintPixelFormat(rfbPixelFormat *format);
 
+/* client data */
+
+void rfbClientSetClientData(rfbClient* client, void* tag, void* data);
+void* rfbClientGetClientData(rfbClient* client, void* tag);
+
+/* protocol extensions */
+
+typedef struct _rfbClientProtocolExtension {
+	int* encodings;
+	/* returns TRUE if the encoding was handled */
+	rfbBool (*handleEncoding)(rfbClient* cl,
+		rfbFramebufferUpdateRectHeader* rect);
+	/* returns TRUE if it handled the message */
+	rfbBool (*handleMessage)(rfbClient* cl,
+		 rfbServerToClientMsg* message);
+	struct _rfbClientProtocolExtension* next;
+} rfbClientProtocolExtension;
+
+void rfbClientRegisterExtension(rfbClientProtocolExtension* e);
+
 /* sockets.c */
 
 extern rfbBool errorMessageOnReadFailure;