frostfs-sdk-go/resolver/nns.go
Leonard Lyubich 146fc4f07a [#179] resolver: Refactor and document the package
Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>
2022-04-13 10:46:27 +03:00

117 lines
3.4 KiB
Go

package resolver
import (
"context"
"errors"
"fmt"
nns "github.com/nspcc-dev/neo-go/examples/nft-nd-nns"
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.Client interface wrapper, needed for testing
neoClient interface {
invoke(contract util.Uint160, method string, prm []smartcontract.Parameter) (*result.Invoke, error)
}
}
// client is a core implementation of internal NNS.neoClient which is used by NNS.Dial.
type client neoclient.Client
func (x *client) invoke(contract util.Uint160, method string, prm []smartcontract.Parameter) (*result.Invoke, error) {
return (*neoclient.Client)(x).InvokeFunction(contract, method, prm, nil)
}
// Dial connects to the address of the NNS server. If fails, the instance
// SHOULD NOT be used.
func (n *NNS) Dial(address string) error {
cli, err := neoclient.New(context.Background(), address, neoclient.Options{})
if err != nil {
return fmt.Errorf("create neo client: %w", err)
}
if err = cli.Init(); err != nil {
return fmt.Errorf("initialize neo client: %w", err)
}
nnsContract, err := cli.GetContractStateByID(1)
if err != nil {
return fmt.Errorf("get NNS contract state: %w", err)
}
n.neoClient = (*client)(cli)
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.invoke(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
}