122 lines
4.1 KiB
Go
122 lines
4.1 KiB
Go
/*
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Package nns provide some RPC wrappers for the non-native NNS contract.
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It's not yet a complete interface because there are different NNS versions
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available, yet it provides the most widely used ones that were available from
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the old RPC client API.
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*/
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package nns
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import (
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"fmt"
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"github.com/google/uuid"
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"github.com/nspcc-dev/neo-go/pkg/neorpc/result"
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"github.com/nspcc-dev/neo-go/pkg/rpcclient/unwrap"
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"github.com/nspcc-dev/neo-go/pkg/util"
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"github.com/nspcc-dev/neo-go/pkg/vm/stackitem"
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)
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// Invoker is used by ContractReader to call various methods.
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type Invoker interface {
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Call(contract util.Uint160, operation string, params ...interface{}) (*result.Invoke, error)
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CallAndExpandIterator(contract util.Uint160, method string, maxItems int, params ...interface{}) (*result.Invoke, error)
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TerminateSession(sessionID uuid.UUID) error
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TraverseIterator(sessionID uuid.UUID, iterator *result.Iterator, num int) ([]stackitem.Item, error)
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}
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// ContractReader provides an interface to call read-only NNS contract methods.
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type ContractReader struct {
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invoker Invoker
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hash util.Uint160
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}
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// RecordIterator is used for iterating over GetAllRecords results.
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type RecordIterator struct {
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client Invoker
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session uuid.UUID
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iterator result.Iterator
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}
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// NewReader creates an instance of ContractReader that can be used to read
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// data from the contract.
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func NewReader(invoker Invoker, hash util.Uint160) *ContractReader {
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return &ContractReader{invoker, hash}
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}
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// GetPrice returns current domain registration price in GAS.
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func (c *ContractReader) GetPrice() (int64, error) {
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return unwrap.Int64(c.invoker.Call(c.hash, "getPrice"))
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}
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// IsAvailable checks whether the domain given is available for registration.
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func (c *ContractReader) IsAvailable(name string) (bool, error) {
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return unwrap.Bool(c.invoker.Call(c.hash, "isAvailable", name))
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}
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// Resolve resolves the given record type for the given domain (with no more
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// than three redirects).
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func (c *ContractReader) Resolve(name string, typ RecordType) (string, error) {
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return unwrap.UTF8String(c.invoker.Call(c.hash, "resolve", name, int64(typ)))
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}
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// GetAllRecords returns an iterator that allows to retrieve all RecordState
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// items for the given domain name. It depends on the server to provide proper
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// session-based iterator, but can also work with expanded one.
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func (c *ContractReader) GetAllRecords(name string) (*RecordIterator, error) {
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sess, iter, err := unwrap.SessionIterator(c.invoker.Call(c.hash, "getAllRecords", name))
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if err != nil {
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return nil, err
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}
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return &RecordIterator{
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client: c.invoker,
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iterator: iter,
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session: sess,
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}, nil
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}
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// Next returns the next set of elements from the iterator (up to num of them).
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// It can return less than num elements in case iterator doesn't have that many
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// or zero elements if the iterator has no more elements or the session is
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// expired.
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func (r *RecordIterator) Next(num int) ([]RecordState, error) {
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items, err := r.client.TraverseIterator(r.session, &r.iterator, num)
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if err != nil {
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return nil, err
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}
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return itemsToRecords(items)
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}
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// Terminate closes the iterator session used by RecordIterator (if it's
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// session-based).
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func (r *RecordIterator) Terminate() error {
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if r.iterator.ID == nil {
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return nil
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}
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return r.client.TerminateSession(r.session)
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}
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// GetAllRecordsExpanded is similar to GetAllRecords (uses the same NNS
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// method), but can be useful if the server used doesn't support sessions and
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// doesn't expand iterators. It creates a script that will get num of result
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// items from the iterator right in the VM and return them to you. It's only
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// limited by VM stack and GAS available for RPC invocations.
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func (c *ContractReader) GetAllRecordsExpanded(name string, num int) ([]RecordState, error) {
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arr, err := unwrap.Array(c.invoker.CallAndExpandIterator(c.hash, "getAllRecords", num, name))
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if err != nil {
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return nil, err
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}
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return itemsToRecords(arr)
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}
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func itemsToRecords(arr []stackitem.Item) ([]RecordState, error) {
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res := make([]RecordState, len(arr))
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for i := range arr {
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err := res[i].FromStackItem(arr[i])
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if err != nil {
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return nil, fmt.Errorf("item #%d: %w", i, err)
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}
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}
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return res, nil
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}
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