Add util

util/addr/addr.go

@@ -0,0 +1,126 @@
+package addr
+
+import (
+	"fmt"
+	"net"
+)
+
+var (
+	privateBlocks []*net.IPNet
+)
+
+func init() {
+	for _, b := range []string{"10.0.0.0/8", "172.16.0.0/12", "192.168.0.0/16", "100.64.0.0/10", "fd00::/8"} {
+		if _, block, err := net.ParseCIDR(b); err == nil {
+			privateBlocks = append(privateBlocks, block)
+		}
+	}
+}
+
+func isPrivateIP(ipAddr string) bool {
+	ip := net.ParseIP(ipAddr)
+	for _, priv := range privateBlocks {
+		if priv.Contains(ip) {
+			return true
+		}
+	}
+	return false
+}
+
+// Extract returns a real ip
+func Extract(addr string) (string, error) {
+	// if addr specified then its returned
+	if len(addr) > 0 && (addr != "0.0.0.0" && addr != "[::]") {
+		return addr, nil
+	}
+
+	ifaces, err := net.Interfaces()
+	if err != nil {
+		return "", fmt.Errorf("Failed to get interfaces! Err: %v", err)
+	}
+
+	var addrs []net.Addr
+	for _, iface := range ifaces {
+		ifaceAddrs, err := iface.Addrs()
+		if err != nil {
+			// ignore error, interface can dissapear from system
+			continue
+		}
+		addrs = append(addrs, ifaceAddrs...)
+	}
+
+	var ipAddr []byte
+	var publicIP []byte
+
+	for _, rawAddr := range addrs {
+		var ip net.IP
+		switch addr := rawAddr.(type) {
+		case *net.IPAddr:
+			ip = addr.IP
+		case *net.IPNet:
+			ip = addr.IP
+		default:
+			continue
+		}
+
+		if !isPrivateIP(ip.String()) {
+			publicIP = ip
+			continue
+		}
+
+		ipAddr = ip
+		break
+	}
+
+	// return private ip
+	if ipAddr != nil {
+		return net.IP(ipAddr).String(), nil
+	}
+
+	// return public or virtual ip
+	if publicIP != nil {
+		return net.IP(publicIP).String(), nil
+	}
+
+	return "", fmt.Errorf("No IP address found, and explicit IP not provided")
+}
+
+// IPs returns all known ips
+func IPs() []string {
+	ifaces, err := net.Interfaces()
+	if err != nil {
+		return nil
+	}
+
+	var ipAddrs []string
+
+	for _, i := range ifaces {
+		addrs, err := i.Addrs()
+		if err != nil {
+			continue
+		}
+
+		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 {
+				continue
+			}
+
+			ip = ip.To4()
+			if ip == nil {
+				continue
+			}
+
+			ipAddrs = append(ipAddrs, ip.String())
+		}
+	}
+
+	return ipAddrs
+}