package ns import ( "context" "errors" "fmt" "net/url" nns "github.com/nspcc-dev/neo-go/examples/nft-nd-nns" "github.com/nspcc-dev/neo-go/pkg/core/state" neoclient "github.com/nspcc-dev/neo-go/pkg/rpc/client" "github.com/nspcc-dev/neo-go/pkg/rpc/response/result" "github.com/nspcc-dev/neo-go/pkg/smartcontract" "github.com/nspcc-dev/neo-go/pkg/util" "github.com/nspcc-dev/neo-go/pkg/vm" "github.com/nspcc-dev/neo-go/pkg/vm/stackitem" cid "github.com/nspcc-dev/neofs-sdk-go/container/id" ) // NNS looks up NeoFS names using Neo Name Service. // // Instances are created with a variable declaration. Before work, the connection // to the NNS server MUST be established using Dial method. type NNS struct { nnsContract util.Uint160 neoClient neoClient } // represents virtual connection to Neo network used by NNS.Dial. type neoClient interface { // calls specified method of the Neo smart contract with provided parameters. call(contract util.Uint160, method string, prm []smartcontract.Parameter) (*result.Invoke, error) } // implements neoClient using Neo HTTP client. // // note: see NNS.Dial to realize why this isn't defined as type wrapper like neoWebSocket. type neoHTTP struct { *neoclient.Client } func (x *neoHTTP) call(contract util.Uint160, method string, prm []smartcontract.Parameter) (*result.Invoke, error) { return x.Client.InvokeFunction(contract, method, prm, nil) } // implements neoClient using Neo WebSocket client. type neoWebSocket neoclient.WSClient func (x *neoWebSocket) call(contract util.Uint160, method string, prm []smartcontract.Parameter) (*result.Invoke, error) { return (*neoclient.WSClient)(x).InvokeFunction(contract, method, prm, nil) } // Dial connects to the address of the NNS server. If fails, the instance // MUST NOT be used. // // If URL address scheme is 'ws' or 'wss', then WebSocket protocol is used, // otherwise HTTP. func (n *NNS) Dial(address string) error { // multiSchemeClient unites neoClient and common interface of // neoclient.Client and neoclient.WSClient. Interface is anonymous // according to assumption that common interface of these client types // is not required by design and may diverge with changes. var multiSchemeClient interface { neoClient // Init turns client to "ready-to-work" state. Init() error // GetContractStateByID returns state of the NNS contract on 1 input. GetContractStateByID(int32) (*state.Contract, error) } uri, err := url.Parse(address) if err == nil && (uri.Scheme == "ws" || uri.Scheme == "wss") { cWebSocket, err := neoclient.NewWS(context.Background(), address, neoclient.Options{}) if err != nil { return fmt.Errorf("create Neo WebSocket client: %w", err) } multiSchemeClient = (*neoWebSocket)(cWebSocket) } else { cHTTP, err := neoclient.New(context.Background(), address, neoclient.Options{}) if err != nil { return fmt.Errorf("create Neo HTTP client: %w", err) } // if neoHTTP is defined as type wrapper // type neoHTTP neoclient.Client // then next assignment causes compilation error // multiSchemeClient = (*neoHTTP)(cHTTP) multiSchemeClient = &neoHTTP{ Client: cHTTP, } } if err = multiSchemeClient.Init(); err != nil { return fmt.Errorf("initialize Neo client: %w", err) } nnsContract, err := multiSchemeClient.GetContractStateByID(1) if err != nil { return fmt.Errorf("get NNS contract state: %w", err) } n.neoClient = multiSchemeClient n.nnsContract = nnsContract.Hash return nil } // ResolveContainerName looks up for NNS TXT records for the given container name // by calling `resolve` method of NNS contract. Returns the first record which represents // valid container ID in a string format. Otherwise, returns an error. // // ResolveContainerName MUST NOT be called before successful Dial. // // See also https://docs.neo.org/docs/en-us/reference/nns.html. func (n *NNS) ResolveContainerName(name string) (*cid.ID, error) { res, err := n.neoClient.call(n.nnsContract, "resolve", []smartcontract.Parameter{ { Type: smartcontract.StringType, Value: name + ".container", }, { Type: smartcontract.IntegerType, Value: int64(nns.TXT), }, }) if err != nil { return nil, fmt.Errorf("invoke NNS contract: %w", err) } if res.State != vm.HaltState.String() { return nil, fmt.Errorf("NNS contract fault exception: %s", res.FaultException) } else if len(res.Stack) == 0 { return nil, errors.New("empty stack in invocation result") } itemArr, err := res.Stack[len(res.Stack)-1].Convert(stackitem.ArrayT) // top stack element is last in the array if err != nil { return nil, fmt.Errorf("convert stack item to %s", stackitem.ArrayT) } if _, ok := itemArr.(stackitem.Null); !ok { arr, ok := itemArr.Value().([]stackitem.Item) if !ok { // unexpected for types from stackitem package return nil, errors.New("invalid cast to stack item slice") } var id cid.ID for i := range arr { bs, err := arr[i].TryBytes() if err != nil { return nil, fmt.Errorf("convert array item to byte slice: %w", err) } err = id.Parse(string(bs)) if err == nil { return &id, nil } } } return nil, errNotFound }