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package dhcpv4
import (
"fmt"
"net"
"strings"
"github.com/u-root/u-root/pkg/uio"
)
// Route is a classless static route as per RFC 3442.
type Route struct {
// Dest is the destination network.
Dest *net.IPNet
// Router is the router to use for the given destination network.
Router net.IP
}
// Marshal implements uio.Marshaler.
//
// Format described in RFC 3442:
//
// <size of mask in number of bits>
// <destination address, omitting octets that must be zero per mask>
// <route IP>
func (r Route) Marshal(buf *uio.Lexer) {
ones, _ := r.Dest.Mask.Size()
buf.Write8(uint8(ones))
// Only write the non-zero octets.
dstLen := (ones + 7) / 8
buf.WriteBytes(r.Dest.IP.To4()[:dstLen])
buf.WriteBytes(r.Router.To4())
}
// Unmarshal implements uio.Unmarshaler.
func (r *Route) Unmarshal(buf *uio.Lexer) error {
maskSize := buf.Read8()
if maskSize > 32 {
return fmt.Errorf("invalid mask length %d in route option", maskSize)
}
r.Dest = &net.IPNet{
IP: make([]byte, net.IPv4len),
Mask: net.CIDRMask(int(maskSize), 32),
}
dstLen := (maskSize + 7) / 8
buf.ReadBytes(r.Dest.IP[:dstLen])
r.Router = buf.CopyN(net.IPv4len)
return buf.Error()
}
// String prints the destination network and router IP.
func (r *Route) String() string {
return fmt.Sprintf("route to %s via %s", r.Dest, r.Router)
}
// Routes is a collection of network routes.
type Routes []*Route
// FromBytes parses routes from a set of bytes as described by RFC 3442.
func (r *Routes) FromBytes(p []byte) error {
buf := uio.NewBigEndianBuffer(p)
for buf.Has(1) {
var route Route
if err := route.Unmarshal(buf); err != nil {
return err
}
*r = append(*r, &route)
}
return buf.FinError()
}
// ToBytes marshals a set of routes as described by RFC 3442.
func (r Routes) ToBytes() []byte {
buf := uio.NewBigEndianBuffer(nil)
for _, route := range r {
route.Marshal(buf)
}
return buf.Data()
}
// String prints all routes.
func (r Routes) String() string {
s := make([]string, 0, len(r))
for _, route := range r {
s = append(s, route.String())
}
return strings.Join(s, "; ")
}
// OptClasslessStaticRoute returns a new DHCPv4 Classless Static Route
// option.
//
// The Classless Static Route option is described by RFC 3442.
func OptClasslessStaticRoute(routes ...*Route) Option {
return Option{
Code: OptionClasslessStaticRoute,
Value: Routes(routes),
}
}
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