Merge pull request #323 from Natolumin/return_concrete_type_from_conn_creation

server{4,6}: Return UDPConn from NewIPv*UDPConn

2 files changed, 21 insertions, 4 deletions

diff --git a/dhcpv4/server4/conn.go b/dhcpv4/server4/conn.go
index 84d6aa3..0a4c73a 100644
--- a/dhcpv4/server4/conn.go
+++ b/dhcpv4/server4/conn.go
@@ -1,6 +1,7 @@
 package server4
 
 import (
+	"errors"
 	"fmt"
 	"net"
 	"os"
@@ -13,7 +14,7 @@ import (
 // given based on a IPv4 DGRAM socket. The UDP connection allows broadcasting.
 //
 // The interface must already be configured.
-func NewIPv4UDPConn(iface string, port int) (net.PacketConn, error) {
+func NewIPv4UDPConn(iface string, port int) (*net.UDPConn, error) {
 	fd, err := unix.Socket(unix.AF_INET, unix.SOCK_DGRAM, unix.IPPROTO_UDP)
 	if err != nil {
 		return nil, fmt.Errorf("cannot get a UDP socket: %v", err)
@@ -41,5 +42,13 @@ func NewIPv4UDPConn(iface string, port int) (net.PacketConn, error) {
 		return nil, fmt.Errorf("cannot bind to port %d: %v", port, err)
 	}
 
-	return net.FilePacketConn(f)
+	conn, err := net.FilePacketConn(f)
+	if err != nil {
+		return nil, err
+	}
+	udpconn, ok := conn.(*net.UDPConn)
+	if !ok {
+		return nil, errors.New("BUG(dhcp4): incorrect socket type, expected UDP")
+	}
+	return udpconn, nil
 }
diff --git a/dhcpv6/server6/conn.go b/dhcpv6/server6/conn.go
index 08c54e8..cbf72b4 100644
--- a/dhcpv6/server6/conn.go
+++ b/dhcpv6/server6/conn.go
@@ -15,7 +15,7 @@ import (
 // As a bonus, you can actually listen on a multicast address instead of being punted to the wildcard
 //
 // The interface must already be configured.
-func NewIPv6UDPConn(iface string, addr *net.UDPAddr) (net.PacketConn, error) {
+func NewIPv6UDPConn(iface string, addr *net.UDPAddr) (*net.UDPConn, error) {
 	fd, err := unix.Socket(unix.AF_INET6, unix.SOCK_DGRAM, unix.IPPROTO_UDP)
 	if err != nil {
 		return nil, fmt.Errorf("cannot get a UDP socket: %v", err)
@@ -58,5 +58,13 @@ func NewIPv6UDPConn(iface string, addr *net.UDPAddr) (net.PacketConn, error) {
 		return nil, fmt.Errorf("cannot bind to address %v: %v", addr, err)
 	}
 
-	return net.FilePacketConn(f)
+	conn, err := net.FilePacketConn(f)
+	if err != nil {
+		return nil, err
+	}
+	udpconn, ok := conn.(*net.UDPConn)
+	if !ok {
+		return nil, errors.New("BUG(dhcp6): incorrect socket type, expected UDP")
+	}
+	return udpconn, nil
 }