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authordscho <dscho>2005-10-06 19:23:26 +0000
committerdscho <dscho>2005-10-06 19:23:26 +0000
commit11fc700c5db6afc6978211f5735707848b94ae8e (patch)
tree76101bd2488e55e0669a3513d6a04a354d1e27a2
parent5c1fdb47d31fcf17b37c82b9aa95d887f1c22f6a (diff)
downloadlibtdevnc-11fc700c5db6afc6978211f5735707848b94ae8e.tar.gz
libtdevnc-11fc700c5db6afc6978211f5735707848b94ae8e.zip
add BackChannel extension example
-rw-r--r--examples/Makefile.am2
-rw-r--r--examples/backchannel.c113
2 files changed, 114 insertions, 1 deletions
diff --git a/examples/Makefile.am b/examples/Makefile.am
index 2a14db9..b936e77 100644
--- a/examples/Makefile.am
+++ b/examples/Makefile.am
@@ -14,6 +14,6 @@ noinst_HEADERS=radon.h
noinst_PROGRAMS=example pnmshow regiontest pnmshow24 fontsel \
vncev storepasswd colourmaptest simple simple15 $(MAC) \
- $(FILETRANSFER)
+ $(FILETRANSFER) backchannel
diff --git a/examples/backchannel.c b/examples/backchannel.c
new file mode 100644
index 0000000..4db01a8
--- /dev/null
+++ b/examples/backchannel.c
@@ -0,0 +1,113 @@
+#include <rfb/rfb.h>
+
+/*
+ * This is a simple example demonstrating a protocol extension.
+ *
+ * The "back channel" permits sending commands between client and server.
+ * It works by sending plain text messages.
+ *
+ * As suggested in the RFB protocol, the back channel is enabled by asking
+ * for a "pseudo encoding", and enabling the back channel on the client side
+ * as soon as it gets a back channel message from the server.
+ *
+ * This implements the server part.
+ *
+ * Note: If you design your own extension and want it to be useful for others,
+ * too, you should make sure that
+ *
+ * - your server as well as your client can speak to other clients and
+ * servers respectively (i.e. they are nice if they are talking to a
+ * program which does not know about your extension).
+ *
+ * - if the machine is little endian, all 16-bit and 32-bit integers are
+ * swapped before they are sent and after they are received.
+ *
+ */
+
+#define rfbBackChannel 155
+
+typedef struct backChannelMsg {
+ uint8_t type;
+ uint8_t pad1;
+ uint16_t pad2;
+ uint32_t size;
+} backChannelMsg;
+
+rfbBool enableBackChannel(rfbClientPtr cl, void* data, int encoding)
+{
+ if(encoding == rfbBackChannel) {
+ backChannelMsg msg;
+ const char* text="Server acknowledges back channel encoding\n";
+ uint32_t length = strlen(text)+1;
+ int n;
+
+ rfbLog("Enabling the back channel\n");
+
+ msg.type = rfbBackChannel;
+ msg.size = Swap32IfLE(length);
+ if((n = rfbWriteExact(cl, (char*)&msg, sizeof(msg))) <= 0 ||
+ (n = rfbWriteExact(cl, text, length)) <= 0) {
+ rfbLogPerror("enableBackChannel: write");
+ }
+ return TRUE;
+ }
+ return FALSE;
+}
+
+static rfbBool handleBackChannelMessage(rfbClientPtr cl, void* data,
+ const rfbClientToServerMsg* message)
+{
+ if(message->type == rfbBackChannel) {
+ backChannelMsg msg;
+ char* text;
+ int n;
+ if((n = rfbReadExact(cl, ((char*)&msg)+1, sizeof(backChannelMsg)-1)) <= 0) {
+ if(n != 0)
+ rfbLogPerror("handleBackChannelMessage: read");
+ rfbCloseClient(cl);
+ return TRUE;
+ }
+ msg.size = Swap32IfLE(msg.size);
+ if((text = malloc(msg.size)) == NULL) {
+ rfbErr("Could not allocate %d bytes\n", msg.size);
+ return TRUE;
+ }
+ if((n = rfbReadExact(cl, text, msg.size)) <= 0) {
+ if(n != 0)
+ rfbLogPerror("handleBackChannelMessage: read");
+ rfbCloseClient(cl);
+ return TRUE;
+ }
+ rfbLog("got message:\n%s\n", text);
+ free(text);
+ return TRUE;
+ }
+ return FALSE;
+}
+
+static int backChannelEncodings[] = {rfbBackChannel, 0};
+
+static rfbProtocolExtension backChannelExtension = {
+ NULL, /* newClient */
+ NULL, /* init */
+ backChannelEncodings, /* pseudoEncodings */
+ enableBackChannel, /* enablePseudoEncoding */
+ handleBackChannelMessage, /* handleMessage */
+ NULL, /* close */
+ NULL, /* usage */
+ NULL, /* processArgument */
+ NULL /* next extension */
+};
+
+int main(int argc,char** argv)
+{
+ rfbScreenInfoPtr server;
+
+ rfbRegisterProtocolExtension(&backChannelExtension);
+
+ server=rfbGetScreen(&argc,argv,400,300,8,3,4);
+ server->frameBuffer=(char*)malloc(400*300*4);
+ rfbInitServer(server);
+ rfbRunEventLoop(server,-1,FALSE);
+ return(0);
+}