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// Copyright 2018-present the CoreDHCP Authors. All rights reserved
// This source code is licensed under the MIT license found in the
// LICENSE file in the root directory of this source tree.
// Package allocators provides the interface and the algorithm(s) for allocation of ipv6
// prefixes of various sizes within a larger prefix.
// There are many many parallels with memory allocation.
package allocators
import (
"errors"
"fmt"
"net"
)
// Allocator is the interface to the address allocator. It only finds and
// allocates blocks and is not concerned with lease-specific questions like
// expiration (ie garbage collection needs to be handled separately)
type Allocator interface {
// Allocate finds a suitable prefix of the given size and returns it.
//
// hint is a prefix, which the client desires especially, and that the
// allocator MAY try to return; the allocator SHOULD try to return a prefix of
// the same size as the given hint prefix. The allocator MUST NOT return an
// error if a prefix was successfully assigned, even if the prefix has nothing
// in common with the hinted prefix
Allocate(hint net.IPNet) (net.IPNet, error)
// Free returns the prefix containing the given network to the pool
//
// Free may return a DoubleFreeError if the prefix being returned was not
// previously allocated
Free(net.IPNet) error
}
// ErrDoubleFree is an error type returned by Allocator.Free() when a
// non-allocated block is passed
type ErrDoubleFree struct {
Loc net.IPNet
}
// String returns a human-readable error message for a DoubleFree error
func (err *ErrDoubleFree) Error() string {
return fmt.Sprint("Attempted to free unallocated block at ", err.Loc.String())
}
// ErrNoAddrAvail is returned when we can't allocate an IP because there's no unallocated space left
var ErrNoAddrAvail = errors.New("no address available to allocate")
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