Update dependencies

vendor/github.com/insomniacslk/dhcp/dhcpv4/option_subnet_mask.go

@@ -0,0 +1,40 @@
+package dhcpv4
+
+import (
+	"net"
+
+	"github.com/u-root/uio/uio"
+)
+
+// IPMask represents an option encapsulating the subnet mask.
+//
+// This option implements the subnet mask option in RFC 2132, Section 3.3.
+type IPMask net.IPMask
+
+// ToBytes returns a serialized stream of bytes for this option.
+func (im IPMask) ToBytes() []byte {
+	if len(im) > net.IPv4len {
+		return im[:net.IPv4len]
+	}
+	return im
+}
+
+// String returns a human-readable string.
+func (im IPMask) String() string {
+	return net.IPMask(im).String()
+}
+
+// FromBytes parses im from data per RFC 2132.
+func (im *IPMask) FromBytes(data []byte) error {
+	buf := uio.NewBigEndianBuffer(data)
+	*im = IPMask(buf.CopyN(net.IPv4len))
+	return buf.FinError()
+}
+
+// OptSubnetMask returns a new DHCPv4 SubnetMask option per RFC 2132, Section 3.3.
+func OptSubnetMask(mask net.IPMask) Option {
+	return Option{
+		Code:  OptionSubnetMask,
+		Value: IPMask(mask),
+	}
+}