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")
}

// IsValidHash checks whether a given hash is valid (b58 decodable, len > 0)
func IsValidHash(s string) bool {
	out := b58.Decode(s)
	if out == nil || len(out) == 0 {
		return false
	}
	_, err := mh.Cast(out)
	if err != nil {
		return false
	}
	return true
}

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

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

	ipnsKey := key.Key(h)
	val, err := r.routing.GetValue(ctx, ipnsKey)
	if err != nil {
		log.Warning("RoutingResolve get failed.")
		return "", err
	}

	entry := new(pb.IpnsEntry)
	err = proto.Unmarshal(val, entry)
	if err != nil {
		return "", err
	}

	// name should be a public key retrievable from ipfs
	pubkey, err := routing.GetPublicKey(r.routing, ctx, hash)
	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
		return path.ParsePath(string(entry.GetValue()))
	} else {
		// Its an old style multihash record
		log.Warning("Detected old style multihash record")
		return path.FromKey(key.Key(valh)), nil
	}
}

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

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

func Decode(encoding, digest string) (mh.Multihash, error) {
	switch encoding {
	case "raw":
		return mh.Cast([]byte(digest))
	case "hex":
		return hex.DecodeString(digest)
	case "base58":
		return base58.Decode(digest), nil
	case "base64":
		return base64.StdEncoding.DecodeString(digest)
	default:
		return nil, fmt.Errorf("unknown encoding: %s", encoding)
	}
}

func (cs *cliqueService) listenToTells() error {
	messageIn, err := cs.listen("tell")
	if err != nil {
		return err
	}

	tellChan := make(chan *tellMessage)

	go func() {
		for {
			select {
			case <-messageIn:
			case <-cs.ctx.Done():
				return

			case message := <-messageIn:

				// Check if the message is a valid node key
				_, err := mh.Cast(message.data)
				if err != nil {
					log.Printf("Cliqueservice got an invalid tell node key")
					continue
				}

				signatureNodeKey := key.Key(message.data)
				nodePromise := cs.ipfsNode.DAG.GetNodes(cs.ctx, []key.Key{signatureNodeKey})[0]

				go func() {
					if node, err := nodePromise.Get(cs.ctx); err == nil {
						signatureNodeInOut <- node
					}
				}()

			case signatureNode := <-tellChan:

				ok, err := verifySignatureNode(cs.ipfsNode, signatureNode)
				if err != nil {
					log.Printf("Cliqueservice failed to verify a signature node: %s\n", err)
					continue
				}

				if !ok {
					log.Printf("Cliqueservice received an invalid signature node.\n")
				}
			}
		}
	}()

	return nil
}

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() (k key.Key, ok bool) {
		select {
		case <-ctx.Done():
			return k, false
		case e, more := <-res.Next():
			if !more {
				return k, false
			}
			if e.Error != nil {
				log.Debug("blockstore.AllKeysChan got err:", e.Error)
				return k, false
			}

			// need to convert to key.Key using key.KeyFromDsKey.
			k = key.KeyFromDsKey(ds.NewKey(e.Key))
			log.Debug("blockstore: query got key", k)

			// key must be a multihash. else ignore it.
			_, err := mh.Cast([]byte(k))
			if err != nil {
				return "", true
			}

			return k, true
		}
	}

	output := make(chan key.Key)
	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
}

// 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
}