chore: Get Next Immediate Port (#157)

Author: sivanantham-gnanavel

net/port.go

@@ -46,6 +46,25 @@ func GetFreePort() (Port, error) {
 	return Port(l.Addr().(*net.TCPAddr).Port), nil
 }
 
+// GetNextFreePort - returns the immediate next port if it's available. The maximum allowed input is 65534, since we increment the value by 1.
+func GetNextFreePort(port string) (Port, error) {
+	if port == "" || port == "0" {
+		return 0, errors.New("invalid starting port")
+	}
+	p, err := strconv.Atoi(port)
+	if err != nil || p <= 0 || p >= 65535 {
+		return 0, errors.New("invalid port number (must be between 1 and 65534)")
+	}
+	nextPort := p + 1
+	addr := &net.TCPAddr{IP: net.ParseIP("127.0.0.1"), Port: nextPort}
+	l, err := net.ListenTCP("tcp", addr)
+	if err != nil {
+		return 0, err
+	}
+	defer l.Close()
+	return Port(l.Addr().(*net.TCPAddr).Port), nil
+}
+
 // ParsePort - parses string into Port
 func ParsePort(s string) (p Port, err error) {
 	switch s {