X-Git-Url: http://git.osdn.net/view?a=blobdiff_plain;f=p2p%2Fexternal_ip.go;fp=p2p%2Fexternal_ip.go;h=5c2c90cfeb03e25850aa25d24a08b54a3756aa92;hb=54373c1a3efe0e373ec1605840a4363e4b246c46;hp=0000000000000000000000000000000000000000;hpb=ee01d543fdfe1fd0a4d548965c66f7923ea7b062;p=bytom%2Fvapor.git

diff --git a/p2p/external_ip.go b/p2p/external_ip.go
new file mode 100644
index 00000000..5c2c90cf
--- /dev/null
+++ b/p2p/external_ip.go
@@ -0,0 +1,47 @@
+package p2p
+
+import (
+	"net"
+)
+
+// ExternalIPv4 returns the first IPv4 available.
+func ExternalIPv4() (string, error) {
+	ifaces, err := net.Interfaces()
+	if err != nil {
+		return "", err
+	}
+
+	for _, iface := range ifaces {
+		// interface down
+		if iface.Flags&net.FlagUp == 0 {
+			continue
+		}
+		// loopback interface
+		if iface.Flags&net.FlagLoopback != 0 {
+			continue
+		}
+		addrs, err := iface.Addrs()
+		if err != nil {
+			return "", err
+		}
+
+		for _, addr := range addrs {
+			var ip net.IP
+			switch v := addr.(type) {
+			case *net.IPNet:
+				ip = v.IP
+			case *net.IPAddr:
+				ip = v.IP
+			}
+			if ip == nil || ip.IsLoopback() {
+				continue
+			}
+			ip = ip.To4()
+			if ip == nil {
+				continue // not an ipv4 address
+			}
+			return ip.String(), nil
+		}
+	}
+	return "127.0.0.1", nil
+}