server4: Use port 0 in tests

Tests use a randPort() workaround for not using port 0, as port 0 is not
usable with raw sockets.
We don't actually use raw sockets, so port 0 is fine, this makes use of
it which ensures we avoid port collisions.

Signed-off-by: Anatole Denis <natolumin@unverle.fr>

1 files changed, 6 insertions, 12 deletions

diff --git a/dhcpv4/server4/server_test.go b/dhcpv4/server4/server_test.go
index e64be09..da2b199 100644
--- a/dhcpv4/server4/server_test.go
+++ b/dhcpv4/server4/server_test.go
@@ -22,13 +22,6 @@ func init() {
 	rand.Seed(time.Now().UTC().UnixNano())
 }
 
-func randPort() int {
-	// can't use port 0 with raw sockets, so until we implement
-	// a non-raw-sockets client for non-static ports, we have to
-	// deal with this "randomness"
-	return 32*1024 + rand.Intn(65536-32*1024)
-}
-
 // DORAHandler is a server handler suitable for DORA transactions
 func DORAHandler(conn net.PacketConn, peer net.Addr, m *dhcpv4.DHCPv4) {
 	if m == nil {
@@ -65,27 +58,28 @@ func DORAHandler(conn net.PacketConn, peer net.Addr, m *dhcpv4.DHCPv4) {
 func setUpClientAndServer(t *testing.T, iface net.Interface, handler Handler) (*nclient4.Client, *Server) {
 	// strong assumption, I know
 	loAddr := net.ParseIP("127.0.0.1")
-	saddr := net.UDPAddr{
+	saddr := &net.UDPAddr{
 		IP:   loAddr,
-		Port: randPort(),
+		Port: 0,
 	}
 	caddr := net.UDPAddr{
 		IP:   loAddr,
-		Port: randPort(),
+		Port: 0,
 	}
-	s, err := NewServer("", &saddr, handler)
+	s, err := NewServer("", saddr, handler)
 	if err != nil {
 		t.Fatal(err)
 	}
 	go func() {
 		_ = s.Serve()
 	}()
+	saddr = s.conn.LocalAddr().(*net.UDPAddr)
 
 	clientConn, err := NewIPv4UDPConn("", &caddr)
 	if err != nil {
 		t.Fatal(err)
 	}
-	c, err := nclient4.NewWithConn(clientConn, iface.HardwareAddr, nclient4.WithServerAddr(&saddr))
+	c, err := nclient4.NewWithConn(clientConn, iface.HardwareAddr, nclient4.WithServerAddr(saddr))
 	if err != nil {
 		t.Fatal(err)
 	}