123 lines
2.9 KiB
Go
123 lines
2.9 KiB
Go
// Copyright (C) 2018 Storj Labs, Inc.
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// See LICENSE for copying information.
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package audit
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import (
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"context"
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"crypto/rand"
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"math/big"
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"sync"
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"github.com/vivint/infectious"
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"storj.io/storj/pkg/eestream"
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"storj.io/storj/pkg/paths"
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"storj.io/storj/pkg/pb"
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"storj.io/storj/pkg/pointerdb/pdbclient"
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"storj.io/storj/pkg/storage/meta"
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)
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// Stripe keeps track of a stripe's index and its parent segment
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type Stripe struct {
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Index int
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Segment *pb.Pointer
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}
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// Cursor keeps track of audit location in pointer db
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type Cursor struct {
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pointers pdbclient.Client
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lastPath *paths.Path
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mutex sync.Mutex
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}
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// NewCursor creates a Cursor which iterates over pointer db
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func NewCursor(pointers pdbclient.Client) *Cursor {
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return &Cursor{pointers: pointers}
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}
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// NextStripe returns a random stripe to be audited
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func (cursor *Cursor) NextStripe(ctx context.Context) (stripe *Stripe, err error) {
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cursor.mutex.Lock()
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defer cursor.mutex.Unlock()
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var pointerItems []pdbclient.ListItem
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var path paths.Path
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var more bool
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if cursor.lastPath == nil {
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pointerItems, more, err = cursor.pointers.List(ctx, nil, nil, nil, true, 0, meta.None)
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} else {
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pointerItems, more, err = cursor.pointers.List(ctx, nil, *cursor.lastPath, nil, true, 0, meta.None)
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}
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if err != nil {
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return nil, err
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}
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// get random pointer
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pointerItem, err := getRandomPointer(pointerItems)
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if err != nil {
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return nil, err
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}
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// get path
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path = pointerItem.Path
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// keep track of last path listed
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if !more {
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cursor.lastPath = nil
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} else {
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cursor.lastPath = &pointerItems[len(pointerItems)-1].Path
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}
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// get pointer info
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pointer, err := cursor.pointers.Get(ctx, path)
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if err != nil {
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return nil, err
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}
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// create the erasure scheme so we can get the stripe size
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es, err := makeErasureScheme(pointer.GetRemote().GetRedundancy())
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if err != nil {
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return nil, err
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}
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//get random stripe
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index, err := getRandomStripe(es, pointer)
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if err != nil {
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return nil, err
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}
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return &Stripe{Index: index, Segment: pointer}, nil
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}
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// create the erasure scheme
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func makeErasureScheme(rs *pb.RedundancyScheme) (eestream.ErasureScheme, error) {
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fc, err := infectious.NewFEC(int(rs.GetMinReq()), int(rs.GetTotal()))
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if err != nil {
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return nil, err
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}
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es := eestream.NewRSScheme(fc, int(rs.GetErasureShareSize()))
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return es, nil
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}
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func getRandomStripe(es eestream.ErasureScheme, pointer *pb.Pointer) (index int, err error) {
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stripeSize := es.StripeSize()
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randomStripeIndex, err := rand.Int(rand.Reader, big.NewInt(pointer.GetSize()/int64(stripeSize)))
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if err != nil {
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return -1, err
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}
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return int(randomStripeIndex.Int64()), nil
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}
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func getRandomPointer(pointerItems []pdbclient.ListItem) (pointer pdbclient.ListItem, err error) {
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randomNum, err := rand.Int(rand.Reader, big.NewInt(int64(len(pointerItems))))
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if err != nil {
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return pdbclient.ListItem{}, err
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}
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randomNumInt64 := randomNum.Int64()
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pointerItem := pointerItems[randomNumInt64]
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return pointerItem, nil
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}
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