dhcpv4: simplify host name and boot file handling.

3 files changed, 47 insertions, 78 deletions

diff --git a/dhcpv4/bsdp/bsdp_test.go b/dhcpv4/bsdp/bsdp_test.go
index 9da86fa..610b8d6 100644
--- a/dhcpv4/bsdp/bsdp_test.go
+++ b/dhcpv4/bsdp/bsdp_test.go
@@ -274,7 +274,7 @@ func TestNewReplyForInformList(t *testing.T) {
 	require.NoError(t, err)
 	require.Equal(t, net.IP{1, 2, 3, 4}, ack.ClientIPAddr())
 	require.Equal(t, net.IPv4zero, ack.YourIPAddr())
-	require.Equal(t, "bsdp.foo.com", ack.ServerHostNameToString())
+	require.Equal(t, "bsdp.foo.com", ack.ServerHostName())
 
 	// Validate options.
 	RequireHasOption(t, ack, &dhcpv4.OptMessageType{MessageType: dhcpv4.MessageTypeAck})
@@ -355,7 +355,7 @@ func TestNewReplyForInformSelect(t *testing.T) {
 	require.NoError(t, err)
 	require.Equal(t, net.IP{1, 2, 3, 4}, ack.ClientIPAddr())
 	require.Equal(t, net.IPv4zero, ack.YourIPAddr())
-	require.Equal(t, "bsdp.foo.com", ack.ServerHostNameToString())
+	require.Equal(t, "bsdp.foo.com", ack.ServerHostName())
 
 	// Validate options.
 	RequireHasOption(t, ack, &dhcpv4.OptMessageType{MessageType: dhcpv4.MessageTypeAck})
diff --git a/dhcpv4/dhcpv4.go b/dhcpv4/dhcpv4.go
index 56554eb..35e1917 100644
--- a/dhcpv4/dhcpv4.go
+++ b/dhcpv4/dhcpv4.go
@@ -43,8 +43,8 @@ type DHCPv4 struct {
 	serverIPAddr   net.IP
 	gatewayIPAddr  net.IP
 	clientHwAddr   net.HardwareAddr
-	serverHostName [64]byte
-	bootFileName   [128]byte
+	serverHostName string
+	bootFileName   string
 	options        []Option
 }
 
@@ -123,11 +123,8 @@ func New() (*DHCPv4, error) {
 		yourIPAddr:    net.IPv4zero,
 		serverIPAddr:  net.IPv4zero,
 		gatewayIPAddr: net.IPv4zero,
+		options:       make([]Option, 0, 10),
 	}
-	copy(d.serverHostName[:], []byte{})
-	copy(d.bootFileName[:], []byte{})
-
-	d.options = make([]Option, 0, 10)
 	// the End option has to be added explicitly
 	d.AddOption(&OptionGeneric{OptionCode: OptionEnd})
 	return &d, nil
@@ -295,8 +292,21 @@ func FromBytes(q []byte) (*DHCPv4, error) {
 	buf.ReadBytes(p.clientHwAddr)
 	p.clientHwAddr = p.clientHwAddr[:hwAddrLen]
 
-	buf.ReadBytes(p.serverHostName[:])
-	buf.ReadBytes(p.bootFileName[:])
+	var sname [64]byte
+	buf.ReadBytes(sname[:])
+	length := strings.Index(string(sname[:]), "\x00")
+	if length == -1 {
+		length = 64
+	}
+	p.serverHostName = string(sname[:length])
+
+	var file [128]byte
+	buf.ReadBytes(file[:])
+	length = strings.Index(string(file[:]), "\x00")
+	if length == -1 {
+		length = 128
+	}
+	p.bootFileName = string(file[:length])
 
 	var cookie [4]byte
 	buf.ReadBytes(cookie[:])
@@ -488,57 +498,25 @@ func (d *DHCPv4) SetClientHwAddr(clientHwAddr net.HardwareAddr) {
 }
 
 // ServerHostName returns the server host name as a sequence of bytes.
-func (d *DHCPv4) ServerHostName() [64]byte {
+func (d *DHCPv4) ServerHostName() string {
 	return d.serverHostName
 }
 
-// ServerHostNameToString returns the server host name as a string, after
-// trimming the null bytes at the end.
-func (d *DHCPv4) ServerHostNameToString() string {
-	return strings.TrimRight(string(d.serverHostName[:]), "\x00")
-}
-
 // SetServerHostName replaces the server host name, from a sequence of bytes,
 // truncating it to the maximum length of 64.
-func (d *DHCPv4) SetServerHostName(serverHostName []byte) {
-	if len(serverHostName) > 64 {
-		serverHostName = serverHostName[:64]
-	} else if len(serverHostName) < 64 {
-		for i := len(serverHostName) - 1; i < 64; i++ {
-			serverHostName = append(serverHostName, 0)
-		}
-	}
-	// need an array, not a slice, so let's copy it
-	var newServerHostName [64]byte
-	copy(newServerHostName[:], serverHostName)
-	d.serverHostName = newServerHostName
+func (d *DHCPv4) SetServerHostName(serverHostName string) {
+	d.serverHostName = serverHostName
 }
 
 // BootFileName returns the boot file name as a sequence of bytes.
-func (d *DHCPv4) BootFileName() [128]byte {
+func (d *DHCPv4) BootFileName() string {
 	return d.bootFileName
 }
 
-// BootFileNameToString returns the boot file name as a string, after trimming
-// the null bytes at the end.
-func (d *DHCPv4) BootFileNameToString() string {
-	return strings.TrimRight(string(d.bootFileName[:]), "\x00")
-}
-
 // SetBootFileName replaces the boot file name, from a sequence of bytes,
 // truncating it to the maximum length oh 128.
-func (d *DHCPv4) SetBootFileName(bootFileName []byte) {
-	if len(bootFileName) > 128 {
-		bootFileName = bootFileName[:128]
-	} else if len(bootFileName) < 128 {
-		for i := len(bootFileName) - 1; i < 128; i++ {
-			bootFileName = append(bootFileName, 0)
-		}
-	}
-	// need an array, not a slice, so let's copy it
-	var newBootFileName [128]byte
-	copy(newBootFileName[:], bootFileName)
-	d.bootFileName = newBootFileName
+func (d *DHCPv4) SetBootFileName(bootFileName string) {
+	d.bootFileName = bootFileName
 }
 
 // Options returns the DHCPv4 options defined for the packet.
@@ -662,8 +640,8 @@ func (d *DHCPv4) Summary() string {
 		d.ServerIPAddr(),
 		d.GatewayIPAddr(),
 		d.ClientHwAddrToString(),
-		d.ServerHostNameToString(),
-		d.BootFileNameToString(),
+		d.ServerHostName(),
+		d.BootFileName(),
 	)
 	ret += "  options=\n"
 	for _, opt := range d.options {
@@ -752,8 +730,13 @@ func (d *DHCPv4) ToBytes() []byte {
 
 	copy(buf.WriteN(maxHWAddrLen), d.clientHwAddr)
 
-	buf.WriteBytes(d.serverHostName[:])
-	buf.WriteBytes(d.bootFileName[:])
+	var sname [64]byte
+	copy(sname[:], []byte(d.serverHostName))
+	buf.WriteBytes(sname[:])
+
+	var file [128]byte
+	copy(file[:], []byte(d.bootFileName))
+	buf.WriteBytes(file[:])
 
 	// The magic cookie.
 	buf.WriteBytes(magicCookie[:])
diff --git a/dhcpv4/dhcpv4_test.go b/dhcpv4/dhcpv4_test.go
index 27df44d..893377d 100644
--- a/dhcpv4/dhcpv4_test.go
+++ b/dhcpv4/dhcpv4_test.go
@@ -71,10 +71,8 @@ func TestFromBytes(t *testing.T) {
 	require.True(t, d.YourIPAddr().Equal(net.IPv4zero))
 	require.True(t, d.GatewayIPAddr().Equal(net.IPv4zero))
 	require.Equal(t, d.ClientHwAddr(), net.HardwareAddr{0xaa, 0xbb, 0xcc, 0xdd, 0xee, 0xff})
-	hostname := d.ServerHostName()
-	require.Equal(t, hostname[:], expectedHostname)
-	bootfileName := d.BootFileName()
-	require.Equal(t, bootfileName[:], expectedBootfilename)
+	require.Equal(t, d.ServerHostName(), "")
+	require.Equal(t, d.BootFileName(), "")
 	// no need to check Magic Cookie as it is already validated in FromBytes
 	// above
 }
@@ -207,26 +205,14 @@ func TestSettersAndGetters(t *testing.T) {
 	d.SetFlags(0)
 
 	// getter/setter for ServerHostName
-	serverhostname := d.ServerHostName()
-	require.Equal(t, expectedHostname, serverhostname[:])
-	newHostname := []byte{'t', 'e', 's', 't'}
-	for i := 0; i < 60; i++ {
-		newHostname = append(newHostname, 0)
-	}
-	d.SetServerHostName(newHostname)
-	serverhostname = d.ServerHostName()
-	require.Equal(t, newHostname, serverhostname[:])
+	require.Equal(t, "", d.ServerHostName())
+	d.SetServerHostName("test")
+	require.Equal(t, "test", d.ServerHostName())
 
 	// getter/setter for BootFileName
-	bootfilename := d.BootFileName()
-	require.Equal(t, expectedBootfilename, bootfilename[:])
-	newBootfilename := []byte{'t', 'e', 's', 't'}
-	for i := 0; i < 124; i++ {
-		newBootfilename = append(newBootfilename, 0)
-	}
-	d.SetBootFileName(newBootfilename)
-	bootfilename = d.BootFileName()
-	require.Equal(t, newBootfilename, bootfilename[:])
+	require.Equal(t, "", d.BootFileName())
+	d.SetBootFileName("test")
+	require.Equal(t, "test", d.BootFileName())
 }
 
 func TestToStringMethods(t *testing.T) {
@@ -263,12 +249,12 @@ func TestToStringMethods(t *testing.T) {
 	require.Equal(t, "aa:bb:cc:dd:ee:ff", d.ClientHwAddrToString())
 
 	// ServerHostNameToString
-	d.SetServerHostName([]byte("my.host.local"))
-	require.Equal(t, "my.host.local", d.ServerHostNameToString())
+	d.SetServerHostName("my.host.local")
+	require.Equal(t, "my.host.local", d.ServerHostName())
 
 	// BootFileNameToString
-	d.SetBootFileName([]byte("/my/boot/file"))
-	require.Equal(t, "/my/boot/file", d.BootFileNameToString())
+	d.SetBootFileName("/my/boot/file")
+	require.Equal(t, "/my/boot/file", d.BootFileName())
 }
 
 func TestNewToBytes(t *testing.T) {