add delay before returning from windows dhcp otherwise net adapter not found

Author: QxBytes

dhcp/dhcp.go

@@ -234,7 +234,7 @@ func (c *DHCP) receiveDHCPResponse(ctx context.Context, reader io.ReadCloser, xi
 			if opcode != dhcpOpCodeReply {
 				continue // opcode is not a reply, so continue
 			}
-
+			c.logger.Info("Received DHCP reply packet", zap.Int("opCode", int(opcode)), zap.Any("transactionID", TransactionID(txid)))
 			if TransactionID(txid) == xid {
 				break
 			}

dhcp/dhcp_windows.go

@@ -16,6 +16,7 @@ const (
 	dummySubnetMask      = "255.255.128.0"
 	addIPAddressDelay    = 4 * time.Second
 	deleteIPAddressDelay = 2 * time.Second
+	returnDelay          = 8 * time.Second // time to wait before returning from DiscoverRequest
 
 	socketTimeoutMillis = 1000
 )
@@ -97,7 +98,7 @@ func (c *DHCP) DiscoverRequest(ctx context.Context, macAddress net.HardwareAddr,
 	// delete dummy ip off the interface if it already exists
 	ret, err := c.execClient.ExecuteCommand(ctx, "netsh", "interface", "ipv4", "delete", "address", ifName, dummyIPAddressStr)
 	if err != nil {
-		c.logger.Info("Could not remove dummy ip", zap.String("output", ret), zap.Error(err))
+		c.logger.Info("Could not remove dummy ip, likely because it doesn't exist", zap.String("output", ret), zap.Error(err))
 	}
 	time.Sleep(deleteIPAddressDelay)
 
@@ -110,8 +111,10 @@ func (c *DHCP) DiscoverRequest(ctx context.Context, macAddress net.HardwareAddr,
 	defer func() {
 		ret, cleanupErr := c.execClient.ExecuteCommand(ctx, "netsh", "interface", "ipv4", "delete", "address", ifName, dummyIPAddressStr)
 		if cleanupErr != nil {
-			c.logger.Info("Could not remove dummy ip on leaving function", zap.String("output", ret), zap.Error(err))
+			c.logger.Info("Failed to remove dummy ip on leaving function", zap.String("output", ret), zap.Error(err))
 		}
+		// wait for nic to retrieve autoconfiguration ip
+		time.Sleep(returnDelay)
 	}()
 	// it takes time for the address to be assigned
 	time.Sleep(addIPAddressDelay)

network/network_windows.go

@@ -447,6 +447,7 @@ func (nw *networkManager) sendDHCPDiscoverOnSecondary(client dhcpClient, mac net
 	if err != nil {
 		return errors.Wrapf(err, "failed to issue dhcp discover packet to create mapping in host")
 	}
+	logger.Info("Successfully received DHCP reply packet")
 	return nil
 }