synergy hook DLL will now restart itself if a client tries to

init() it while it's already running.  fixed an uninitialized
pointer bug in CServer and some cleanup-on-error code in
CMSWindowsPrimaryScreen.  also added timeout to read() on
IInputStream and a heartbeat sent by clients so the server
can disconnect clients that are dead but never reset the TCP
connection.  previously the server would keep these dead
clients around forever and if the user was locked on the
client screen for some reason then the server would have to
be rebooted (or the server would have to be killed via a
remote login).

synergy/CInputPacketStream.cpp

@@ -1,5 +1,6 @@
 #include "CInputPacketStream.h"
 #include "CLock.h"
+#include "CStopwatch.h"
 
 //
 // CInputPacketStream
@@ -26,14 +27,21 @@ CInputPacketStream::close()
 }
 
 UInt32
-CInputPacketStream::read(void* buffer, UInt32 n)
+CInputPacketStream::read(void* buffer, UInt32 n, double timeout)
 {
 	CLock lock(&m_mutex);
 
-	// wait for entire message to be read.  return immediately if
-	// stream hungup.
-	if (!waitForFullMessage()) {
+	// wait for entire message to be read.  return if stream
+	// hungup or timeout.
+	switch (waitForFullMessage(timeout)) {
+	case kData:
+		break;
+
+	case kHungup:
 		return 0;
+
+	case kTimedout:
+		return (UInt32)-1;
 	}
 
 	// limit number of bytes to read to the number of bytes left in the
@@ -43,7 +51,7 @@ CInputPacketStream::read(void* buffer, UInt32 n)
 	}
 
 	// now read from our buffer
-	n = m_buffer.readNoLock(buffer, n);
+	n = m_buffer.readNoLock(buffer, n, -1.0);
 	assert(n <= m_size);
 	m_size -= n;
 
@@ -60,48 +68,70 @@ CInputPacketStream::getSize() const
 UInt32
 CInputPacketStream::getSizeNoLock() const
 {
+	CStopwatch timer(true);
 	while (!hasFullMessage() && getStream()->getSize() > 0) {
 		// read more data
-		if (!getMoreMessage()) {
+		if (getMoreMessage(-1.0) != kData) {
 			// stream hungup
-			return false;
+			return 0;
 		}
 	}
 
 	return m_size;
 }
 
-bool
-CInputPacketStream::waitForFullMessage() const
+CInputPacketStream::EResult
+CInputPacketStream::waitForFullMessage(double timeout) const
 {
+	CStopwatch timer(true);
 	while (!hasFullMessage()) {
+		// compute remaining timeout
+		double t = timeout - timer.getTime();
+		if (timeout >= 0.0 && t <= 0.0) {
+			// timeout
+			return kTimedout;
+		}
+
 		// read more data
-		if (!getMoreMessage()) {
+		switch (getMoreMessage(t)) {
+		case kData:
+			break;
+
+		case kHungup:
 			// stream hungup
-			return false;
+			return kHungup;
+
+		case kTimedout:
+			// stream timed out
+			return kTimedout;
 		}
 	}
 
-	return true;
+	return kData;
 }
 
-bool
-CInputPacketStream::getMoreMessage() const
+CInputPacketStream::EResult
+CInputPacketStream::getMoreMessage(double timeout) const
 {
 	// read more data
 	char buffer[4096];
-	UInt32 n = getStream()->read(buffer, sizeof(buffer));
+	UInt32 n = getStream()->read(buffer, sizeof(buffer), timeout);
+
+	// return if stream timed out
+	if (n == (UInt32)-1) {
+		return kTimedout;
+	}
 
 	// return if stream hungup
 	if (n == 0) {
 		m_buffer.hangup();
-		return false;
+		return kHungup;
 	}
 
 	// append to our buffer
 	m_buffer.write(buffer, n);
 
-	return true;
+	return kData;
 }
 
 bool
@@ -117,7 +147,7 @@ CInputPacketStream::hasFullMessage() const
 
 		// save payload length
 		UInt8 buffer[4];
-		UInt32 n = m_buffer.readNoLock(buffer, sizeof(buffer));
+		UInt32 n = m_buffer.readNoLock(buffer, sizeof(buffer), -1.0);
 		assert(n == 4);
 		m_size = ((UInt32)buffer[0] << 24) |
 				 ((UInt32)buffer[1] << 16) |