update for dhcp4client changes

internal/dhcp4/dhcp4.go

@@ -3,7 +3,6 @@ package dhcp4
 
 import (
 	"bytes"
-	"crypto/rand"
 	"encoding/binary"
 	"fmt"
 	"log"
@@ -36,7 +35,7 @@ type Client struct {
 	hardwareAddr net.HardwareAddr
 	cfg          Config
 	timeNow      func() time.Time
-	randRead     func([]byte) (int, error)
+	generateXID  func([]byte)
 
 	// last DHCPACK packet for renewal/release
 	ack dhcp4.Packet
@@ -48,9 +47,6 @@ func (c *Client) ObtainOrRenew() bool {
 		if c.timeNow == nil {
 			c.timeNow = time.Now
 		}
-		if c.randRead == nil {
-			c.randRead = rand.Read
-		}
 		if c.connection == nil && c.Interface != nil {
 			pktsock, err := dhcp4client.NewPacketSock(c.Interface.Index)
 			if err != nil {
@@ -71,14 +67,15 @@ func (c *Client) ObtainOrRenew() bool {
 			dhcp4client.Timeout(5*time.Second),
 			dhcp4client.Broadcast(false),
 			dhcp4client.Connection(c.connection),
+			dhcp4client.GenerateXID(c.generateXID),
 		)
 		if err != nil {
 			c.err = err
 			return
 		}
-		dhcp.RandRead = c.randRead
 		c.dhcp = dhcp
 	})
+	c.err = nil // clear previous error
 	// TODO: renew if c.ack != nil, fall back if renewal fails
 	ok, ack, err := c.dhcpRequest()
 	if err != nil {

internal/dhcp4/dhcp4_test.go

@@ -64,13 +64,12 @@ func TestDHCP4(t *testing.T) {
 		hardwareAddr: mac,
 		timeNow:      func() time.Time { return now },
 		connection:   &replayer{pcapr: pcapr},
-		randRead: func(b []byte) (n int, err error) {
+		generateXID: func(b []byte) {
 			if got, want := len(b), 4; got != want {
-				return 0, fmt.Errorf("github.com/d2g/dhcp4client request unexpected amount of bytes: got %d, want %d", got, want)
+				t.Fatalf("github.com/d2g/dhcp4client request unexpected amount of bytes: got %d, want %d", got, want)
 			}
 			// TODO: read the transaction ID from the pcap file
 			copy(b, []byte{0x77, 0x08, 0xd7, 0x24})
-			return len(b), nil
 		},
 	}