2 files changed, 23 insertions, 17 deletions
diff --git a/dhcpv4/bsdp/bsdp.go b/dhcpv4/bsdp/bsdp.go
index 42edf7f..bf84508 100644
--- a/dhcpv4/bsdp/bsdp.go
+++ b/dhcpv4/bsdp/bsdp.go
@@ -37,6 +37,28 @@ func needsReplyPort(replyPort uint16) bool {
 	return replyPort != 0 && replyPort != dhcpv4.ClientPort
 }
 
+// NewInformListForInterface creates a new INFORM packet for interface ifname
+// with configuration options specified by config.
+func NewInformListForInterface(ifname string, replyPort uint16) (*dhcpv4.DHCPv4, error) {
+	iface, err := net.InterfaceByName(ifname)
+	if err != nil {
+		return nil, err
+	}
+	// Get currently configured IP.
+	addrs, err := iface.Addrs()
+	if err != nil {
+		return nil, err
+	}
+	localIPs, err := dhcpv4.GetExternalIPv4Addrs(addrs)
+	if err != nil {
+		return nil, fmt.Errorf("could not get local IPv4 addr for %s: %v", iface.Name, err)
+	}
+	if localIPs == nil || len(localIPs) == 0 {
+		return nil, fmt.Errorf("could not get local IPv4 addr for %s", iface.Name)
+	}
+	return NewInformList(iface.HardwareAddr, localIPs[0], replyPort)
+}
+
 // NewInformList creates a new INFORM packet for interface with hardware address
 // `hwaddr` and IP `localIP`. Packet will be sent out on port `replyPort`.
 func NewInformList(hwaddr net.HardwareAddr, localIP net.IP, replyPort uint16) (*dhcpv4.DHCPv4, error) {
diff --git a/dhcpv4/bsdp/client.go b/dhcpv4/bsdp/client.go
index 38de094..255d54b 100644
--- a/dhcpv4/bsdp/client.go
+++ b/dhcpv4/bsdp/client.go
@@ -2,8 +2,6 @@ package bsdp
 
 import (
 	"errors"
-	"fmt"
-	"net"
 
 	"github.com/insomniacslk/dhcp/dhcpv4"
 )
@@ -51,24 +49,10 @@ func (c *Client) Exchange(ifname string, informList *dhcpv4.DHCPv4) ([]*dhcpv4.D
 	if err != nil {
 		return conversation, err
 	}
-	iface, err := net.InterfaceByName(ifname)
-	if err != nil {
-		return conversation, err
-	}
-
-	// Get currently configured IP.
-	addrs, err := iface.Addrs()
-	if err != nil {
-		return conversation, err
-	}
-	localIPs, err := dhcpv4.GetExternalIPv4Addrs(addrs)
-	if err != nil {
-		return conversation, fmt.Errorf("could not get local IPv4 addr for %s: %v", iface.Name, err)
-	}
 
 	// INFORM[LIST]
 	if informList == nil {
-		informList, err = NewInformList(iface.HardwareAddr, localIPs[0], dhcpv4.ClientPort)
+		informList, err = NewInformListForInterface(ifname, dhcpv4.ClientPort)
 		if err != nil {
 			return conversation, err
 		}