--- libaitmqtt/src/cmds.c	2012/05/03 08:21:28	1.1.2.1
+++ libaitmqtt/src/cmds.c	2012/05/05 13:10:24	1.1.2.2
@@ -1,3 +1,74 @@
 #include "global.h"
 
 
+static inline int
+_wait4data(int sock, u_short ka, short events)
+{
+	int ret = 0;
+	struct pollfd pfd;
+
+	if (sock < 3)
+		return -1;	/* error */
+
+	pfd.fd = sock;
+	pfd.events = POLLOUT;
+	if ((ret = poll(&pfd, 1, ka * 1000)) == -1 || 
+			pfd.revents & (POLLERR | POLLHUP | POLLNVAL)) {
+		LOGERR;
+		return -1;	/* error */
+	} else if (!ret)
+		return 1;	/* timeout */
+
+	return 0;		/* ready */
+}
+
+
+/*
+ * mqtt_KeepAlive() - Keep Alive check routine
+ *
+ * @sock = connected socket
+ * @ka = keep alive timeout
+ * @tries = tries for receive correct ping response, usually ==1
+ * return: -1 error, 0 host is alive, 1 timeout session or 2 broken session
+ */
+int
+mqtt_KeepAlive(int sock, u_short ka, u_char tries)
+{
+	int ret = 0;
+	mqtt_msg_t msg = { NULL, 0 };
+
+	if (sock < 3)
+		return -1;	/* error */
+
+	if ((ret = _wait4data(sock, ka, POLLOUT)))
+		return ret;
+	/* ping request */
+	if ((ret = mqtt_msgPINGREQ(&msg)) == -1)
+		return -1;	/* error */
+	if ((ret = send(sock, msg.msg_base, ret, MSG_NOSIGNAL)) == -1) {
+		LOGERR;
+		goto end;
+	}
+
+	while (tries--) {
+		if ((ret = _wait4data(sock, ka, POLLIN | POLLPRI))) {
+			if (ret == -1)
+				break;
+			else
+				continue;
+		}
+		/* receive & decode packet */
+		if ((ret = recv(sock, msg.msg_base, msg.msg_len, 0)) == -1) {
+			LOGERR;
+			break;
+		}
+		if (!mqtt_readPINGRESP(&msg)) {
+			ret = 0;	/* Host is alive */
+			break;
+		} else
+			ret = 2;	/* Session is broken ... must be disconnect! */
+	}
+end:
+	free(msg.msg_base);
+	return ret;
+}