rpcClient.go

package navcoind

import (
	"bytes"
	"crypto/tls"
	"encoding/json"
	"errors"
	"fmt"
	"go.uber.org/zap"
	"io/ioutil"
	"net/http"
	"time"
)

// A rpcClient represents a JSON RPC client (over HTTP(s)).
type rpcClient struct {
	serverAddr string
	user       string
	passwd     string
	httpClient *http.Client
	timeout    int
	debug      bool
}

// rpcRequest represent a RCP request
type rpcRequest struct {
	Method  string      `json:"method"`
	Params  interface{} `json:"params"`
	Id      int64       `json:"id"`
	JsonRpc string      `json:"jsonrpc"`
}

// RPCErrorCode represents an error code to be used as a part of an RPCError
// which is in turn used in a JSON-RPC Response object.
//
// A specific type is used to help ensure the wrong errors aren't used.
type RPCErrorCode int

// RPCError represents an error that is used as a part of a JSON-RPC Response
// object.
type RPCError struct {
	Code    RPCErrorCode `json:"code,omitempty"`
	Message string       `json:"message,omitempty"`
}

// Guarantee RPCError satisfies the builtin error interface.
var _, _ error = RPCError{}, (*RPCError)(nil)

// Error returns a string describing the RPC error.  This satisfies the
// builtin error interface.
func (e RPCError) Error() string {
	return fmt.Sprintf("%d: %s", e.Code, e.Message)
}

type rpcResponse struct {
	Id     int64           `json:"id"`
	Result json.RawMessage `json:"result"`
	Err    *RPCError       `json:"error"`
}

func newClient(host string, port int, user, passwd string, useSSL bool, timeout int, debug bool) (c *rpcClient, err error) {
	if len(host) == 0 {
		err = errors.New("Bad call missing argument host")
		return
	}
	var serverAddr string
	var httpClient *http.Client
	if useSSL {
		serverAddr = "https://"
		t := &http.Transport{
			TLSClientConfig: &tls.Config{InsecureSkipVerify: true},
		}
		httpClient = &http.Client{Transport: t}
	} else {
		serverAddr = "http://"
		httpClient = &http.Client{}
	}
	c = &rpcClient{
		fmt.Sprintf("%s%s:%d", serverAddr, host, port),
		user,
		passwd,
		httpClient,
		timeout,
		debug,
	}
	return
}

// doTimeoutRequest process a HTTP request with timeout
func (c *rpcClient) doTimeoutRequest(timer *time.Timer, req *http.Request) (*http.Response, error) {
	type result struct {
		resp *http.Response
		err  error
	}
	done := make(chan result, 1)
	go func() {
		resp, err := c.httpClient.Do(req)
		done <- result{resp, err}
	}()
	// Wait for the read or the timeout
	select {
	case r := <-done:
		return r.resp, r.err
	case <-timer.C:
		return nil, errors.New("Timeout reading data from server")
	}
}

// call prepare & exec the request
func (c *rpcClient) call(method string, params interface{}) (rr rpcResponse, err error) {
	rpcR := rpcRequest{method, params, time.Now().UnixNano(), "1.0"}
	payloadBuffer := &bytes.Buffer{}
	jsonEncoder := json.NewEncoder(payloadBuffer)
	err = jsonEncoder.Encode(rpcR)
	if err != nil {
		return
	}

	if c.debug {
		zap.L().With(
			zap.String("request", payloadBuffer.String()),
		).Debug("Navcoind: RPC Request")
	}

	req, err := http.NewRequest("POST", c.serverAddr, payloadBuffer)
	if err != nil {
		return
	}
	req.Header.Add("Content-Type", "application/json;charset=utf-8")
	req.Header.Add("Accept", "application/json")

	// Auth ?
	if len(c.user) > 0 || len(c.passwd) > 0 {
		req.SetBasicAuth(c.user, c.passwd)
	}

	resp, err := c.doTimeoutRequest(time.NewTimer(time.Duration(c.timeout)*time.Second), req)
	if err != nil {
		return
	}
	defer resp.Body.Close()

	data, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		return
	}

	if c.debug {
		zap.L().With(
			zap.String("response", string(data)),
		).Debug("Navcoind: RPC Response")
	}

	err = json.Unmarshal(data, &rr)
	return
}