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package dhcp6opts
import (
"io"
"net"
"time"
"github.com/mdlayher/dhcp6"
"github.com/mdlayher/dhcp6/internal/buffer"
)
// IAAddr represents an Identity Association Address, as defined in RFC 3315,
// Section 22.6.
//
// DHCP clients use identity association addresses (IAAddrs) to request IPv6
// addresses from a DHCP server, using the lifetimes specified in the preferred
// lifetime and valid lifetime fields. Multiple IAAddrs may be present in a
// single DHCP request, but only enscapsulated within an IANA or IATA options
// field.
type IAAddr struct {
// IP specifies the IPv6 address to offer to a client. The validity of the
// address is controlled by the PreferredLifetime and ValidLifetime fields.
IP net.IP
// PreferredLifetime specifies the preferred lifetime of an IPv6 address.
// When the preferred lifetime of an address expires, the address becomes
// deprecated, and should not be used in new communications.
//
// The preferred lifetime of an address must not be greater than its
// valid lifetime.
PreferredLifetime time.Duration
// ValidLifetime specifies the valid lifetime of an IPv6 address. When the
// valid lifetime of an address expires, the address should not be used for
// any further communication.
//
// The valid lifetime of an address must be greater than its preferred
// lifetime.
ValidLifetime time.Duration
// Options specifies a map of DHCP options specific to this IAAddr.
// Its methods can be used to retrieve data from an incoming IAAddr, or
// send data with an outgoing IAAddr.
Options dhcp6.Options
}
// NewIAAddr creates a new IAAddr from an IPv6 address, preferred and valid lifetime
// durations, and an optional Options map.
//
// The IP must be exactly 16 bytes, the correct length for an IPv6 address.
// The preferred lifetime duration must be less than the valid lifetime
// duration. Failure to meet either of these conditions will result in an error.
// If an Options map is not specified, a new one will be allocated.
func NewIAAddr(ip net.IP, preferred time.Duration, valid time.Duration, options dhcp6.Options) (*IAAddr, error) {
// From documentation: If ip is not an IPv4 address, To4 returns nil.
if ip.To4() != nil {
return nil, ErrInvalidIP
}
// Preferred lifetime must always be less than valid lifetime.
if preferred > valid {
return nil, ErrInvalidLifetimes
}
// If no options set, make empty map
if options == nil {
options = make(dhcp6.Options)
}
return &IAAddr{
IP: ip,
PreferredLifetime: preferred,
ValidLifetime: valid,
Options: options,
}, nil
}
// MarshalBinary allocates a byte slice containing the data from a IAAddr.
func (i *IAAddr) MarshalBinary() ([]byte, error) {
// 16 bytes: IPv6 address
// 4 bytes: preferred lifetime
// 4 bytes: valid lifetime
// N bytes: options
b := buffer.New(nil)
copy(b.WriteN(net.IPv6len), i.IP)
b.Write32(uint32(i.PreferredLifetime / time.Second))
b.Write32(uint32(i.ValidLifetime / time.Second))
opts, err := i.Options.MarshalBinary()
if err != nil {
return nil, err
}
b.WriteBytes(opts)
return b.Data(), nil
}
// UnmarshalBinary unmarshals a raw byte slice into a IAAddr.
//
// If the byte slice does not contain enough data to form a valid IAAddr,
// io.ErrUnexpectedEOF is returned. If the preferred lifetime value in the
// byte slice is less than the valid lifetime, ErrInvalidLifetimes is returned.
func (i *IAAddr) UnmarshalBinary(p []byte) error {
b := buffer.New(p)
if b.Len() < 24 {
return io.ErrUnexpectedEOF
}
i.IP = make(net.IP, net.IPv6len)
copy(i.IP, b.Consume(net.IPv6len))
i.PreferredLifetime = time.Duration(b.Read32()) * time.Second
i.ValidLifetime = time.Duration(b.Read32()) * time.Second
// Preferred lifetime must always be less than valid lifetime.
if i.PreferredLifetime > i.ValidLifetime {
return ErrInvalidLifetimes
}
return (&i.Options).UnmarshalBinary(b.Remaining())
}
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