144 lines
3.3 KiB
Go
144 lines
3.3 KiB
Go
package retrieval
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import (
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"context"
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"io"
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blocks "github.com/ipfs/go-block-format"
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"github.com/ipfs/go-cid"
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ipld "github.com/ipfs/go-ipld-format"
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"github.com/ipfs/go-merkledag"
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"github.com/ipfs/go-unixfs"
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pb "github.com/ipfs/go-unixfs/pb"
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"golang.org/x/xerrors"
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"github.com/filecoin-project/go-lotus/build"
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)
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type BlockVerifier interface {
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Verify(context.Context, blocks.Block, io.Writer) (internal bool, err error)
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}
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type OptimisticVerifier struct {
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}
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func (o *OptimisticVerifier) Verify(context.Context, blocks.Block, io.Writer) (bool, error) {
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// It's probably fine
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return false, nil
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}
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type UnixFs0Verifier struct {
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Root cid.Cid
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rootBlk blocks.Block
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expect int
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seen int
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sub *UnixFs0Verifier
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}
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func (b *UnixFs0Verifier) verify(ctx context.Context, blk blocks.Block, out io.Writer) (last bool, internal bool, err error) {
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if b.sub != nil {
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// TODO: check links here (iff b.sub.sub == nil)
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subLast, internal, err := b.sub.verify(ctx, blk, out)
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if err != nil {
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return false, false, err
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}
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if subLast {
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b.sub = nil
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b.seen++
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}
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return b.seen == b.expect, internal, nil
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}
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if b.seen >= b.expect { // this is probably impossible
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return false, false, xerrors.New("unixfs verifier: too many nodes in level")
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}
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links, err := b.checkInternal(blk, out)
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if err != nil {
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return false, false, err
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}
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if links > 0 { // TODO: check if all links are intermediate (or all aren't)
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if links > build.UnixfsLinksPerLevel {
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return false, false, xerrors.New("unixfs verifier: too many links in intermediate node")
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}
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if b.seen+1 == b.expect && links != build.UnixfsLinksPerLevel {
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return false, false, xerrors.New("unixfs verifier: too few nodes in level")
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}
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b.sub = &UnixFs0Verifier{
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Root: blk.Cid(),
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rootBlk: blk,
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expect: links,
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}
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// don't mark as seen yet
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return false, true, nil
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}
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b.seen++
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return b.seen == b.expect, false, nil
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}
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func (b *UnixFs0Verifier) checkInternal(blk blocks.Block, out io.Writer) (int, error) {
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nd, err := ipld.Decode(blk)
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if err != nil {
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log.Warnf("IPLD Decode failed: %s", err)
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return 0, err
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}
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// TODO: check size
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switch nd := nd.(type) {
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case *merkledag.ProtoNode:
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fsn, err := unixfs.FSNodeFromBytes(nd.Data())
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if err != nil {
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log.Warnf("unixfs.FSNodeFromBytes failed: %s", err)
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return 0, err
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}
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if fsn.Type() != pb.Data_File {
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return 0, xerrors.New("internal nodes must be a file")
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}
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if len(fsn.Data()) > 0 {
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return 0, xerrors.New("internal node with data")
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}
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if len(nd.Links()) == 0 {
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return 0, xerrors.New("internal node with no links")
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}
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return len(nd.Links()), nil
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case *merkledag.RawNode:
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_, err := out.Write(nd.RawData())
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return 0, err
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default:
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return 0, xerrors.New("verifier: unknown node type")
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}
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}
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func (b *UnixFs0Verifier) Verify(ctx context.Context, blk blocks.Block, w io.Writer) (bool, error) {
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// root is special
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if b.rootBlk == nil {
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if !b.Root.Equals(blk.Cid()) {
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return false, xerrors.Errorf("unixfs verifier: root block CID didn't match: valid %s, got %s", b.Root, blk.Cid())
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}
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b.rootBlk = blk
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links, err := b.checkInternal(blk, w)
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if err != nil {
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return false, err
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}
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b.expect = links
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return links != 0, nil
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}
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_, internal, err := b.verify(ctx, blk, w)
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return internal, err
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}
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var _ BlockVerifier = &OptimisticVerifier{}
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var _ BlockVerifier = &UnixFs0Verifier{}
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