Extract private ip for registration when 0.0.0.0 is specified as bind address

server/extractor.go

@@ -2,11 +2,24 @@ package server
 
 import (
 	"fmt"
+	"net"
 	"reflect"
 
 	"github.com/myodc/go-micro/registry"
 )
 
+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"} {
+		if _, block, err := net.ParseCIDR(b); err == nil {
+			privateBlocks = append(privateBlocks, block)
+		}
+	}
+}
+
 func extractValue(v reflect.Type) *registry.Value {
 	if v == nil {
 		return nil
@@ -81,3 +94,55 @@ func extractSubValue(typ reflect.Type) *registry.Value {
 	}
 	return extractValue(reqType)
 }
+
+func extractAddress(addr string) (string, error) {
+	if len(addr) > 0 && (addr != "0.0.0.0" && addr != "[::]") {
+		return addr, nil
+	}
+
+	addrs, err := net.InterfaceAddrs()
+	if err != nil {
+		return "", fmt.Errorf("Failed to get interface addresses! Err: %v", err)
+	}
+
+	var ipAddr []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 ip.To4() == nil {
+			continue
+		}
+
+		if !isPrivateIP(ip.String()) {
+			continue
+		}
+
+		ipAddr = ip
+		break
+	}
+
+	if ipAddr == nil {
+		return "", fmt.Errorf("No private IP address found, and explicit IP not provided")
+	}
+
+	return net.IP(ipAddr).String(), nil
+}
+
+func isPrivateIP(ipAddr string) bool {
+	ip := net.ParseIP(ipAddr)
+	for _, priv := range privateBlocks {
+		if priv.Contains(ip) {
+			return true
+		}
+	}
+	return false
+}