Allow client to specify a multicast "keep alive" with -K.

Experiment: lets see if this helps revive stuck multicast sessions.
With "-K <seconds>", the client will send a IGMP-leave/IGMP-join after
<seconds> of no received packets.

os/frisbee.redux/client.c

@@ -57,6 +57,7 @@ int		tracing = 0;
 char		traceprefix[64];
 int		randomize = 1;
 int		zero = 0;
+int		keepalive;
 int		portnum;
 struct in_addr	mcastaddr;
 struct in_addr	mcastif;
@@ -137,7 +138,7 @@ ClientStats_t	Stats;
 #endif
 
 char *usagestr = 
- "usage: frisbee [-drzbn] [-s #] <-p #> <-m ipaddr> <output filename>\n"
+ "usage: frisbee [-drzbnN] [-s #] <-m ipaddr> <-p #> <output filename>\n"
  " -d              Turn on debugging. Multiple -d options increase output.\n"
  " -r              Randomly delay first request by up to one second.\n"
  " -z              Zero fill unused block ranges (default is to seek past).\n"
@@ -149,6 +150,7 @@ char *usagestr =
  " -i mcastif      Specify a multicast interface in dotted notation.\n"
  " -s slice        Output to DOS slice (DOS numbering 1-4)\n"
  "                 NOTE: Must specify a raw disk device for output filename.\n"
+ " -K seconds      Send a multicast keep alive after a period of inactivity.\n"
  "\n"
  "tuning options (if you don't know what they are, don't use em!):\n"
  " -C MB           Max MB of memory to use for network chunk buffering.\n"
@@ -191,7 +193,7 @@ main(int argc, char **argv)
 	int	dostype = -1;
 	int	slice = 0;
 
-	while ((ch = getopt(argc, argv, "dhp:m:s:i:tbznT:r:E:D:C:W:S:M:R:I:ON")) != -1)
+	while ((ch = getopt(argc, argv, "dhp:m:s:i:tbznT:r:E:D:C:W:S:M:R:I:ONK:")) != -1)
 		switch(ch) {
 		case 'd':
 			debug++;
@@ -306,6 +308,12 @@ main(int argc, char **argv)
 			nodecompress = 1;
 			break;
 
+		case 'K':
+			keepalive = atoi(optarg);
+			if (keepalive < 0)
+				keepalive = 0;
+			break;
+
 		case 'h':
 		case '?':
 		default:
@@ -459,6 +467,14 @@ main(int argc, char **argv)
 			DiskStatusCallback = WriterStatusCallback;
 	}
 
+	/*
+	 * Set the MC keepalive counter (but only if we are multicasting!)
+	 */
+	if (broadcast || (ntohl(mcastaddr.s_addr) >> 28) != 14)
+		keepalive = 0;
+	if (keepalive)
+		log("Enabling MC keepalive at %d seconds", keepalive);
+
 	PlayFrisbee();
 
 	if (tracing) {
@@ -499,12 +515,14 @@ void *
 ClientRecvThread(void *arg)
 {
 	Packet_t	packet, *p = &packet;
-	int		IdleCounter, BackOff;
+	int		IdleCounter, BackOff, KACounter;
 	static int	gotone;
 
 	if (debug)
 		log("Receive pthread starting up ...");
 
+	KACounter = keepalive * TIMEOUT_HZ;
+
 	/*
 	 * Use this to control the rate at which we request blocks.
 	 * The IdleCounter is how many ticks we let pass without a
@@ -549,6 +567,23 @@ ClientRecvThread(void *arg)
 		 */
 		if (PacketReceive(p) != 0) {
 			pthread_testcancel();
+
+			/*
+			 * See if we should send a keep alive
+			 */
+			if (KACounter == 1) {
+				/* If for some reason it fails, stop trying */
+				if (debug)
+					log("sending keepalive...");
+				if (NetMCKeepAlive()) {
+					log("Multicast keepalive failed, "
+					    "disabling keepalive");
+					keepalive = 0;
+				}
+				KACounter = keepalive * TIMEOUT_HZ;
+			} else if (KACounter > 1)
+				KACounter--;
+
 			if (--IdleCounter <= 0) {
 				if (gotone)
 					DOSTAT(recvidles++);
@@ -569,6 +604,8 @@ ClientRecvThread(void *arg)
 			continue;
 		}
 		pthread_testcancel();
+		if (keepalive)
+			KACounter = keepalive * TIMEOUT_HZ;
 		gotone = 1;
 
 		if (! PacketValid(p, TotalChunkCount)) {

os/frisbee.redux/decls.h

@@ -320,7 +320,7 @@ typedef struct {
 int	GetSockbufSize(void);
 int	ClientNetInit(void);
 int	ServerNetInit(void);
-int	ServerNetMCKeepAlive(void);
+int	NetMCKeepAlive(void);
 unsigned long ClientNetID(void);
 int	PacketReceive(Packet_t *p);
 void	PacketSend(Packet_t *p, int *resends);

os/frisbee.redux/network.c

@@ -249,7 +249,7 @@ ServerNetInit(void)
  * We need a better way to do this!
  */
 int
-ServerNetMCKeepAlive(void)
+NetMCKeepAlive(void)
 {
 	struct ip_mreq mreq;
 

os/frisbee.redux/server.c

@@ -604,7 +604,7 @@ ServerRecvThread(void *arg)
 		pthread_testcancel();
 		if (PacketReceive(p) != 0) {
 			if (keepalive && ++idles > keepalive) {
-				if (ServerNetMCKeepAlive()) {
+				if (NetMCKeepAlive()) {
 					warning("Multicast keepalive failed");
 					if (++kafails > 5) {
 						warning("too many failures, disabled");