package client import ( "bytes" "context" "encoding/json" "errors" "fmt" "net" "net/http" "net/url" "time" "github.com/nspcc-dev/neo-go/pkg/config/netmode" "github.com/nspcc-dev/neo-go/pkg/rpc/request" "github.com/nspcc-dev/neo-go/pkg/rpc/response" ) const ( defaultDialTimeout = 4 * time.Second defaultRequestTimeout = 4 * time.Second defaultClientVersion = "2.0" // number of blocks after which cache is expired cacheTimeout = 100 ) // Client represents the middleman for executing JSON RPC calls // to remote NEO RPC nodes. type Client struct { cli *http.Client endpoint *url.URL network netmode.Magic initDone bool ctx context.Context opts Options requestF func(*request.Raw) (*response.Raw, error) cache cache } // Options defines options for the RPC client. // All values are optional. If any duration is not specified // a default of 4 seconds will be used. type Options struct { // Cert is a client-side certificate, it doesn't work at the moment along // with the other two options below. Cert string Key string CACert string DialTimeout time.Duration RequestTimeout time.Duration } // cache stores cache values for the RPC client methods type cache struct { calculateValidUntilBlock calculateValidUntilBlockCache } // calculateValidUntilBlockCache stores cached number of validators and // cache expiration value in blocks type calculateValidUntilBlockCache struct { validatorsCount uint32 expiresAt uint32 } // New returns a new Client ready to use. You should call Init method to // initialize network magic the client is operating on. func New(ctx context.Context, endpoint string, opts Options) (*Client, error) { url, err := url.Parse(endpoint) if err != nil { return nil, err } if opts.DialTimeout <= 0 { opts.DialTimeout = defaultDialTimeout } if opts.RequestTimeout <= 0 { opts.RequestTimeout = defaultRequestTimeout } httpClient := &http.Client{ Transport: &http.Transport{ DialContext: (&net.Dialer{ Timeout: opts.DialTimeout, }).DialContext, }, Timeout: opts.RequestTimeout, } // TODO(@antdm): Enable SSL. if opts.Cert != "" && opts.Key != "" { } cl := &Client{ ctx: ctx, cli: httpClient, endpoint: url, } cl.opts = opts cl.requestF = cl.makeHTTPRequest return cl, nil } // Init sets magic of the network client connected to. This method should be called // before any transaction-, header- or block-related requests in order to deserialize // responses properly. func (c *Client) Init() error { version, err := c.GetVersion() if err != nil { return fmt.Errorf("failed to get network magic: %w", err) } c.network = version.Magic c.initDone = true return nil } func (c *Client) performRequest(method string, p request.RawParams, v interface{}) error { var r = request.Raw{ JSONRPC: request.JSONRPCVersion, Method: method, RawParams: p.Values, ID: 1, } raw, err := c.requestF(&r) if raw != nil && raw.Error != nil { return raw.Error } else if err != nil { return err } else if raw == nil || raw.Result == nil { return errors.New("no result returned") } return json.Unmarshal(raw.Result, v) } func (c *Client) makeHTTPRequest(r *request.Raw) (*response.Raw, error) { var ( buf = new(bytes.Buffer) raw = new(response.Raw) ) if err := json.NewEncoder(buf).Encode(r); err != nil { return nil, err } req, err := http.NewRequest("POST", c.endpoint.String(), buf) if err != nil { return nil, err } resp, err := c.cli.Do(req) if err != nil { return nil, err } defer resp.Body.Close() // The node might send us proper JSON anyway, so look there first and if // it parses, then it has more relevant data than HTTP error code. err = json.NewDecoder(resp.Body).Decode(raw) if err != nil { if resp.StatusCode != http.StatusOK { err = fmt.Errorf("HTTP %d/%s", resp.StatusCode, http.StatusText(resp.StatusCode)) } else { err = fmt.Errorf("JSON decoding: %w", err) } } if err != nil { return nil, err } return raw, nil } // Ping attempts to create a connection to the endpoint. // and returns an error if there is one. func (c *Client) Ping() error { conn, err := net.DialTimeout("tcp", c.endpoint.Host, defaultDialTimeout) if err != nil { return err } _ = conn.Close() return nil }