Golang go-multihash.Cast函数代码示例

func addressBytesToString(p Protocol, b []byte) (string, error) {
	switch p.Code {

	// ipv4,6
	case P_IP4, P_IP6:
		return net.IP(b).String(), nil

	// tcp udp dccp sctp
	case P_TCP, P_UDP, P_DCCP, P_SCTP:
		i := binary.BigEndian.Uint16(b)
		return strconv.Itoa(int(i)), nil

	case P_IPFS: // ipfs
		// the address is a varint-prefixed multihash string representation
		size, n := ReadVarintCode(b)
		b = b[n:]
		if len(b) != size {
			panic("inconsistent lengths")
		}
		m, err := mh.Cast(b)
		if err != nil {
			return "", err
		}
		return m.B58String(), nil
	}

	return "", fmt.Errorf("unknown protocol")
}

func ParseKeyToPath(txt string) (Path, error) {
	if txt == "" {
		return "", ErrNoComponents
	}

	chk := b58.Decode(txt)
	if len(chk) == 0 {
		return "", errors.New("not a key")
	}

	if _, err := mh.Cast(chk); err != nil {
		return "", err
	}
	return FromKey(key.Key(chk)), nil
}

// Unmarshal decodes raw data into a *Node instance.
// The conversion uses an intermediate PBNode.
func (n *Node) Unmarshal(encoded []byte) error {
	var pbn pb.PBNode
	if err := pbn.Unmarshal(encoded); err != nil {
		return fmt.Errorf("Unmarshal failed. %v", err)
	}

	pbnl := pbn.GetLinks()
	n.Links = make([]*Link, len(pbnl))
	for i, l := range pbnl {
		n.Links[i] = &Link{Name: l.GetName(), Size: l.GetTsize()}
		h, err := mh.Cast(l.GetHash())
		if err != nil {
			return fmt.Errorf("Link hash is not valid multihash. %v", err)
		}
		n.Links[i].Hash = h
	}
	sort.Stable(LinkSlice(n.Links)) // keep links sorted

	n.Data = pbn.GetData()
	return nil
}

// AllKeysChan runs a query for keys from the blockstore.
// this is very simplistic, in the future, take dsq.Query as a param?
//
// AllKeysChan respects context
func (bs *blockstore) AllKeysChan(ctx context.Context) (<-chan key.Key, error) {

	// KeysOnly, because that would be _a lot_ of data.
	q := dsq.Query{KeysOnly: true}
	// datastore/namespace does *NOT* fix up Query.Prefix
	q.Prefix = BlockPrefix.String()
	res, err := bs.datastore.Query(q)
	if err != nil {
		return nil, err
	}

	// this function is here to compartmentalize
	get := func() (key.Key, bool) {
		select {
		case <-ctx.Done():
			return "", false
		case e, more := <-res.Next():
			if !more {
				return "", false
			}
			if e.Error != nil {
				log.Debug("blockstore.AllKeysChan got err:", e.Error)
				return "", false
			}

			// need to convert to key.Key using key.KeyFromDsKey.
			k, err := key.KeyFromDsKey(ds.NewKey(e.Key))
			if err != nil {
				log.Warningf("error parsing key from DsKey: ", err)
				return "", true
			}
			log.Debug("blockstore: query got key", k)

			// key must be a multihash. else ignore it.
			_, err = mh.Cast([]byte(k))
			if err != nil {
				log.Warningf("key from datastore was not a multihash: ", err)
				return "", true
			}

			return k, true
		}
	}

	output := make(chan key.Key, dsq.KeysOnlyBufSize)
	go func() {
		defer func() {
			res.Process().Close() // ensure exit (signals early exit, too)
			close(output)
		}()

		for {
			k, ok := get()
			if !ok {
				return
			}
			if k == "" {
				continue
			}

			select {
			case <-ctx.Done():
				return
			case output <- k:
			}
		}
	}()

	return output, nil
}

// ValidatePublicKeyRecord implements ValidatorFunc and
// verifies that the passed in record value is the PublicKey
// that matches the passed in key.
func ValidatePublicKeyRecord(k key.Key, val []byte) error {
	if len(k) < 5 {
		return errors.New("invalid public key record key")
	}

	prefix := string(k[:4])
	if prefix != "/pk/" {
		return errors.New("key was not prefixed with /pk/")
	}

	keyhash := []byte(k[4:])
	if _, err := mh.Cast(keyhash); err != nil {
		return fmt.Errorf("key did not contain valid multihash: %s", err)
	}

	pkh := u.Hash(val)
	if !bytes.Equal(keyhash, pkh) {
		return errors.New("public key does not match storage key")
	}
	return nil
}

// IDFromBytes cast a string to ID type, and validate
// the id to make sure it is a multihash.
func IDFromBytes(b []byte) (ID, error) {
	if _, err := mh.Cast(b); err != nil {
		return ID(""), err
	}
	return ID(b), nil
}

// IDFromString cast a string to ID type, and validate
// the id to make sure it is a multihash.
func IDFromString(s string) (ID, error) {
	if _, err := mh.Cast([]byte(s)); err != nil {
		return ID(""), err
	}
	return ID(s), nil
}

func TestMultisetRoundtrip(t *testing.T) {
	dstore := dssync.MutexWrap(datastore.NewMapDatastore())
	bstore := blockstore.NewBlockstore(dstore)
	bserv := blockservice.New(bstore, offline.Exchange(bstore))
	dag := merkledag.NewDAGService(bserv)

	fn := func(m map[key.Key]uint16) bool {
		// Convert invalid multihash from input to valid ones
		for k, v := range m {
			if _, err := mh.Cast([]byte(k)); err != nil {
				delete(m, k)
				m[key.Key(u.Hash([]byte(k)))] = v
			}
		}

		// Generate a smaller range for refcounts than full uint64, as
		// otherwise this just becomes overly cpu heavy, splitting it
		// out into too many items. That means we need to convert to
		// the right kind of map. As storeMultiset mutates the map as
		// part of its bookkeeping, this is actually good.
		refcounts := copyMap(m)

		ctx := context.Background()
		n, err := storeMultiset(ctx, dag, refcounts, ignoreKeys)
		if err != nil {
			t.Fatalf("storing multiset: %v", err)
		}

		// Check that the node n is in the DAG
		k, err := n.Key()
		if err != nil {
			t.Fatalf("Could not get key: %v", err)
		}
		_, err = dag.Get(ctx, k)
		if err != nil {
			t.Fatalf("Could not get node: %v", err)
		}

		root := &merkledag.Node{}
		const linkName = "dummylink"
		if err := root.AddNodeLink(linkName, n); err != nil {
			t.Fatalf("adding link to root node: %v", err)
		}

		roundtrip, err := loadMultiset(ctx, dag, root, linkName, ignoreKeys)
		if err != nil {
			t.Fatalf("loading multiset: %v", err)
		}

		orig := copyMap(m)
		success := true
		for k, want := range orig {
			if got, ok := roundtrip[k]; ok {
				if got != want {
					success = false
					t.Logf("refcount changed: %v -> %v for %q", want, got, k)
				}
				delete(orig, k)
				delete(roundtrip, k)
			}
		}
		for k, v := range orig {
			success = false
			t.Logf("refcount missing: %v for %q", v, k)
		}
		for k, v := range roundtrip {
			success = false
			t.Logf("refcount extra: %v for %q", v, k)
		}
		return success
	}
	if err := quick.Check(fn, nil); err != nil {
		t.Fatal(err)
	}
}

// resolveOnce implements resolver. Uses the IPFS routing system to
// resolve SFS-like names.
func (r *routingResolver) resolveOnce(ctx context.Context, name string) (path.Path, error) {
	log.Debugf("RoutingResolve: '%s'", name)
	cached, ok := r.cacheGet(name)
	if ok {
		return cached, nil
	}

	hash, err := mh.FromB58String(name)
	if err != nil {
		// name should be a multihash. if it isn't, error out here.
		log.Warningf("RoutingResolve: bad input hash: [%s]\n", name)
		return "", err
	}

	// use the routing system to get the name.
	// /ipns/<name>
	h := []byte("/ipns/" + string(hash))

	var entry *pb.IpnsEntry
	var pubkey ci.PubKey

	resp := make(chan error, 2)
	go func() {
		ipnsKey := key.Key(h)
		val, err := r.routing.GetValue(ctx, ipnsKey)
		if err != nil {
			log.Warning("RoutingResolve get failed.")
			resp <- err
		}

		entry = new(pb.IpnsEntry)
		err = proto.Unmarshal(val, entry)
		if err != nil {
			resp <- err
		}
		resp <- nil
	}()

	go func() {
		// name should be a public key retrievable from ipfs
		pubk, err := routing.GetPublicKey(r.routing, ctx, hash)
		if err != nil {
			resp <- err
		}
		pubkey = pubk
		resp <- nil
	}()

	for i := 0; i < 2; i++ {
		err = <-resp
		if err != nil {
			return "", err
		}
	}

	hsh, _ := pubkey.Hash()
	log.Debugf("pk hash = %s", key.Key(hsh))

	// check sig with pk
	if ok, err := pubkey.Verify(ipnsEntryDataForSig(entry), entry.GetSignature()); err != nil || !ok {
		return "", fmt.Errorf("Invalid value. Not signed by PrivateKey corresponding to %v", pubkey)
	}

	// ok sig checks out. this is a valid name.

	// check for old style record:
	valh, err := mh.Cast(entry.GetValue())
	if err != nil {
		// Not a multihash, probably a new record
		p, err := path.ParsePath(string(entry.GetValue()))
		if err != nil {
			return "", err
		}

		r.cacheSet(name, p, entry)
		return p, nil
	} else {
		// Its an old style multihash record
		log.Warning("Detected old style multihash record")
		p := path.FromKey(key.Key(valh))
		r.cacheSet(name, p, entry)
		return p, nil
	}
}