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package dhcpv4
import (
"fmt"
"net"
"strings"
"github.com/u-root/u-root/pkg/uio"
)
// IPs are IPv4 addresses from a DHCP packet as used and specified by options
// in RFC 2132, Sections 3.5 through 3.13, 8.2, 8.3, 8.5, 8.6, 8.9, and 8.10.
//
// IPs implements the OptionValue type.
type IPs []net.IP
// FromBytes parses an IPv4 address from a DHCP packet as used and specified by
// options in RFC 2132, Sections 3.5 through 3.13, 8.2, 8.3, 8.5, 8.6, 8.9, and
// 8.10.
func (i *IPs) FromBytes(data []byte) error {
buf := uio.NewBigEndianBuffer(data)
if buf.Len() == 0 {
return fmt.Errorf("IP DHCP options must always list at least one IP")
}
*i = make(IPs, 0, buf.Len()/net.IPv4len)
for buf.Has(net.IPv4len) {
*i = append(*i, net.IP(buf.CopyN(net.IPv4len)))
}
return buf.FinError()
}
// ToBytes marshals IPv4 addresses to a DHCP packet as specified by RFC 2132,
// Section 3.5 et al.
func (i IPs) ToBytes() []byte {
buf := uio.NewBigEndianBuffer(nil)
for _, ip := range i {
buf.WriteBytes(ip.To4())
}
return buf.Data()
}
// String returns a human-readable representation of a list of IPs.
func (i IPs) String() string {
s := make([]string, 0, len(i))
for _, ip := range i {
s = append(s, ip.String())
}
return strings.Join(s, ", ")
}
// GetIPs parses a list of IPs from code in o.
func GetIPs(code OptionCode, o Options) []net.IP {
v := o.Get(code)
if v == nil {
return nil
}
var ips IPs
if err := ips.FromBytes(v); err != nil {
return nil
}
return []net.IP(ips)
}
// GetRouter parses the DHCPv4 Router option if present.
//
// The Router option is described by RFC 2132, Section 3.5.
func GetRouter(o Options) []net.IP {
return GetIPs(OptionRouter, o)
}
// OptRouter returns a new DHCPv4 Router option.
//
// The Router option is described by RFC 2132, Section 3.5.
func OptRouter(routers ...net.IP) Option {
return Option{
Code: OptionRouter,
Value: IPs(routers),
}
}
// WithRouter updates a packet with the DHCPv4 Router option.
func WithRouter(routers ...net.IP) Modifier {
return WithOption(OptRouter(routers...))
}
// GetNTPServers parses the DHCPv4 NTP Servers option if present.
//
// The NTP servers option is described by RFC 2132, Section 8.3.
func GetNTPServers(o Options) []net.IP {
return GetIPs(OptionNTPServers, o)
}
// OptNTPServers returns a new DHCPv4 NTP Server option.
//
// The NTP servers option is described by RFC 2132, Section 8.3.
func OptNTPServers(ntpServers ...net.IP) Option {
return Option{
Code: OptionNTPServers,
Value: IPs(ntpServers),
}
}
// GetDNS parses the DHCPv4 Domain Name Server option if present.
//
// The DNS server option is described by RFC 2132, Section 3.8.
func GetDNS(o Options) []net.IP {
return GetIPs(OptionDomainNameServer, o)
}
// OptDNS returns a new DHCPv4 Domain Name Server option.
//
// The DNS server option is described by RFC 2132, Section 3.8.
func OptDNS(servers ...net.IP) Option {
return Option{
Code: OptionDomainNameServer,
Value: IPs(servers),
}
}
// WithDNS modifies a packet with the DHCPv4 Domain Name Server option.
func WithDNS(servers ...net.IP) Modifier {
return WithOption(OptDNS(servers...))
}
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