gitsrc · September 2, 2021 06:45 · Sep 17, 2015
diff --git a/ipcalc.go b/ipcalc.go
@@ -0,0 +1,84 @@
+package main
+
+import (
+	"net"
+	"os/exec"
+
+	"github.com/k0kubun/pp"
+)
+
+func Hosts(cidr string) ([]string, error) {
+	ip, ipnet, err := net.ParseCIDR(cidr)
+	if err != nil {
+		return nil, err
+	}
+
+	var ips []string
+	for ip := ip.Mask(ipnet.Mask); ipnet.Contains(ip); inc(ip) {
+		ips = append(ips, ip.String())
+	}
+	// remove network address and broadcast address
+	return ips[1 : len(ips)-1], nil
+}
+
+//  http://play.golang.org/p/m8TNTtygK0
+func inc(ip net.IP) {
+	for j := len(ip) - 1; j >= 0; j-- {
+		ip[j]++
+		if ip[j] > 0 {
+			break
+		}
+	}
+}
+
+type Pong struct {
+	Ip    string
+	Alive bool
+}
+
+func ping(pingChan <-chan string, pongChan chan<- Pong) {
+	for ip := range pingChan {
+		_, err := exec.Command("ping", "-c1", "-t1", ip).Output()
+		var alive bool
+		if err != nil {
+			alive = false
+		} else {
+			alive = true
+		}
+		pongChan <- Pong{Ip: ip, Alive: alive}
+	}
+}
+
+func receivePong(pongNum int, pongChan <-chan Pong, doneChan chan<- []Pong) {
+	var alives []Pong
+	for i := 0; i < pongNum; i++ {
+		pong := <-pongChan
+		//  fmt.Println("received:", pong)
+		if pong.Alive {
+			alives = append(alives, pong)
+		}
+	}
+	doneChan <- alives
+}
+
+func main() {
+	hosts, _ := Hosts("192.168.11.0/24")
+	concurrentMax := 100
+	pingChan := make(chan string, concurrentMax)
+	pongChan := make(chan Pong, len(hosts))
+	doneChan := make(chan []Pong)
+
+	for i := 0; i < concurrentMax; i++ {
+		go ping(pingChan, pongChan)
+	}
+
+	go receivePong(len(hosts), pongChan, doneChan)
+
+	for _, ip := range hosts {
+		pingChan <- ip
+		//  fmt.Println("sent: " + ip)
+	}
+
+	alives := <-doneChan
+	pp.Println(alives)
+}