swarm: codebase split from go-ethereum (#1405)

chunk/chunk.go

@@ -0,0 +1,261 @@
+// Copyright 2019 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package chunk
+
+import (
+	"context"
+	"errors"
+	"fmt"
+
+	"github.com/ethereum/go-ethereum/common"
+)
+
+const (
+	DefaultSize   = 4096
+	MaxPO         = 16
+	AddressLength = 32
+)
+
+var (
+	ErrChunkNotFound = errors.New("chunk not found")
+	ErrChunkInvalid  = errors.New("invalid chunk")
+)
+
+type Chunk interface {
+	Address() Address
+	Data() []byte
+}
+
+type chunk struct {
+	addr  Address
+	sdata []byte
+}
+
+func NewChunk(addr Address, data []byte) Chunk {
+	return &chunk{
+		addr:  addr,
+		sdata: data,
+	}
+}
+
+func (c *chunk) Address() Address {
+	return c.addr
+}
+
+func (c *chunk) Data() []byte {
+	return c.sdata
+}
+
+func (self *chunk) String() string {
+	return fmt.Sprintf("Address: %v Chunksize: %v", self.addr.Log(), len(self.sdata))
+}
+
+type Address []byte
+
+var ZeroAddr = Address(common.Hash{}.Bytes())
+
+func (a Address) Hex() string {
+	return fmt.Sprintf("%064x", []byte(a[:]))
+}
+
+func (a Address) Log() string {
+	if len(a[:]) < 8 {
+		return fmt.Sprintf("%x", []byte(a[:]))
+	}
+	return fmt.Sprintf("%016x", []byte(a[:8]))
+}
+
+func (a Address) String() string {
+	return fmt.Sprintf("%064x", []byte(a))
+}
+
+func (a Address) MarshalJSON() (out []byte, err error) {
+	return []byte(`"` + a.String() + `"`), nil
+}
+
+func (a *Address) UnmarshalJSON(value []byte) error {
+	s := string(value)
+	*a = make([]byte, 32)
+	h := common.Hex2Bytes(s[1 : len(s)-1])
+	copy(*a, h)
+	return nil
+}
+
+// Proximity returns the proximity order of the MSB distance between x and y
+//
+// The distance metric MSB(x, y) of two equal length byte sequences x an y is the
+// value of the binary integer cast of the x^y, ie., x and y bitwise xor-ed.
+// the binary cast is big endian: most significant bit first (=MSB).
+//
+// Proximity(x, y) is a discrete logarithmic scaling of the MSB distance.
+// It is defined as the reverse rank of the integer part of the base 2
+// logarithm of the distance.
+// It is calculated by counting the number of common leading zeros in the (MSB)
+// binary representation of the x^y.
+//
+// (0 farthest, 255 closest, 256 self)
+func Proximity(one, other []byte) (ret int) {
+	b := (MaxPO-1)/8 + 1
+	if b > len(one) {
+		b = len(one)
+	}
+	m := 8
+	for i := 0; i < b; i++ {
+		oxo := one[i] ^ other[i]
+		for j := 0; j < m; j++ {
+			if (oxo>>uint8(7-j))&0x01 != 0 {
+				return i*8 + j
+			}
+		}
+	}
+	return MaxPO
+}
+
+// ModeGet enumerates different Getter modes.
+type ModeGet int
+
+func (m ModeGet) String() string {
+	switch m {
+	case ModeGetRequest:
+		return "Request"
+	case ModeGetSync:
+		return "Sync"
+	case ModeGetLookup:
+		return "Lookup"
+	default:
+		return "Unknown"
+	}
+}
+
+// Getter modes.
+const (
+	// ModeGetRequest: when accessed for retrieval
+	ModeGetRequest ModeGet = iota
+	// ModeGetSync: when accessed for syncing or proof of custody request
+	ModeGetSync
+	// ModeGetLookup: when accessed to lookup a a chunk in feeds or other places
+	ModeGetLookup
+)
+
+// ModePut enumerates different Putter modes.
+type ModePut int
+
+func (m ModePut) String() string {
+	switch m {
+	case ModePutRequest:
+		return "Request"
+	case ModePutSync:
+		return "Sync"
+	case ModePutUpload:
+		return "Upload"
+	default:
+		return "Unknown"
+	}
+}
+
+// Putter modes.
+const (
+	// ModePutRequest: when a chunk is received as a result of retrieve request and delivery
+	ModePutRequest ModePut = iota
+	// ModePutSync: when a chunk is received via syncing
+	ModePutSync
+	// ModePutUpload: when a chunk is created by local upload
+	ModePutUpload
+)
+
+// ModeSet enumerates different Setter modes.
+type ModeSet int
+
+func (m ModeSet) String() string {
+	switch m {
+	case ModeSetAccess:
+		return "Access"
+	case ModeSetSync:
+		return "Sync"
+	case ModeSetRemove:
+		return "Remove"
+	default:
+		return "Unknown"
+	}
+}
+
+// Setter modes.
+const (
+	// ModeSetAccess: when an update request is received for a chunk or chunk is retrieved for delivery
+	ModeSetAccess ModeSet = iota
+	// ModeSetSync: when a chunk is added to a pull sync batch or when a push sync receipt is received
+	ModeSetSync
+	// ModeSetRemove: when a chunk is removed
+	ModeSetRemove
+)
+
+// Descriptor holds information required for Pull syncing. This struct
+// is provided by subscribing to pull index.
+type Descriptor struct {
+	Address Address
+	BinID   uint64
+}
+
+func (d *Descriptor) String() string {
+	if d == nil {
+		return ""
+	}
+	return fmt.Sprintf("%s bin id %v", d.Address.Hex(), d.BinID)
+}
+
+type Store interface {
+	Get(ctx context.Context, mode ModeGet, addr Address) (ch Chunk, err error)
+	Put(ctx context.Context, mode ModePut, ch Chunk) (exists bool, err error)
+	Has(ctx context.Context, addr Address) (yes bool, err error)
+	Set(ctx context.Context, mode ModeSet, addr Address) (err error)
+	LastPullSubscriptionBinID(bin uint8) (id uint64, err error)
+	SubscribePull(ctx context.Context, bin uint8, since, until uint64) (c <-chan Descriptor, stop func())
+	Close() (err error)
+}
+
+// Validator validates a chunk.
+type Validator interface {
+	Validate(ch Chunk) bool
+}
+
+// ValidatorStore encapsulates Store by decorting the Put method
+// with validators check.
+type ValidatorStore struct {
+	Store
+	validators []Validator
+}
+
+// NewValidatorStore returns a new ValidatorStore which uses
+// provided validators to validate chunks on Put.
+func NewValidatorStore(store Store, validators ...Validator) (s *ValidatorStore) {
+	return &ValidatorStore{
+		Store:      store,
+		validators: validators,
+	}
+}
+
+// Put overrides Store put method with validators check. If one of the validators
+// return true, the chunk is considered valid and Store Put method is called.
+// If all validators return false, ErrChunkInvalid is returned.
+func (s *ValidatorStore) Put(ctx context.Context, mode ModePut, ch Chunk) (exists bool, err error) {
+	for _, v := range s.validators {
+		if v.Validate(ch) {
+			return s.Store.Put(ctx, mode, ch)
+		}
+	}
+	return false, ErrChunkInvalid
+}