forked from btcsuite/btcrpcclient
/
infrastructure.go
1066 lines (923 loc) · 31.9 KB
/
infrastructure.go
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// Copyright (c) 2014 Conformal Systems LLC.
// Use of this source code is governed by an ISC
// license that can be found in the LICENSE file.
package btcrpcclient
import (
"bytes"
"container/list"
"crypto/tls"
"crypto/x509"
"encoding/base64"
"encoding/json"
"errors"
"fmt"
"github.com/conformal/btcjson"
"github.com/conformal/btcws"
"github.com/conformal/go-socks"
"github.com/conformal/websocket"
"net"
"net/http"
"net/url"
"sync"
"sync/atomic"
"time"
)
var (
// ErrInvalidAuth is an error to describe the condition where the client
// is either unable to authenticate or the specified endpoint is
// incorrect.
ErrInvalidAuth = errors.New("authentication failure")
// ErrInvalidEndpoint is an error to describe the condition where the
// websocket handshake failed with the specified endpoint.
ErrInvalidEndpoint = errors.New("the endpoint either does not support " +
"websockets or does not exist")
// ErrClientDisconnect is an error to describe the condition where the
// client has been disconnected from the RPC server. When the
// DisableAutoReconnect option is not set, any outstanding futures
// when a client disconnect occurs will return this error as will
// any new requests.
ErrClientDisconnect = errors.New("the client has been disconnected")
// ErrClientShutdown is an error to describe the condition where the
// client is either already shutdown, or in the process of shutting
// down. Any outstanding futures when a client shutdown occurs will
// return this error as will any new requests.
ErrClientShutdown = errors.New("the client has been shutdown")
)
const (
// sendBufferSize is the number of elements the websocket send channel
// can queue before blocking.
sendBufferSize = 50
// sendPostBufferSize is the number of elements the HTTP POST send
// channel can queue before blocking.
sendPostBufferSize = 100
// connectionRetryInterval is the amount of time to wait in between
// retries when automatically reconnecting to an RPC server.
connectionRetryInterval = time.Second * 5
)
// futureResult holds information about a future promise to deliver the result
// of an asynchronous request.
type futureResult struct {
reply *btcjson.Reply
err error
}
// sendPostDetails houses an HTTP POST request to send to an RPC server as well
// as the original JSON-RPC command and a channel to reply on when the server
// responds with the result.
type sendPostDetails struct {
command btcjson.Cmd
request *http.Request
responseChan chan *futureResult
}
// jsonRequest holds information about a json request that is used to properly
// detect, interpret, and deliver a reply to it.
type jsonRequest struct {
cmd btcjson.Cmd
responseChan chan *futureResult
}
// Client represents a Bitcoin RPC client which allows easy access to the
// various RPC methods available on a Bitcoin RPC server. Each of the wrapper
// functions handle the details of converting the passed and return types to and
// from the underlying JSON types which are required for the JSON-RPC
// invocations
//
// The client provides each RPC in both synchronous (blocking) and asynchronous
// (non-blocking) forms. The asynchronous forms are based on the concept of
// futures where they return an instance of a type that promises to deliver the
// result of the invocation at some future time. Invoking the Receive method on
// the returned future will block until the result is available if it's not
// already.
type Client struct {
id uint64 // atomic, so must stay 64-bit aligned
// config holds the connection configuration assoiated with this client.
config *ConnConfig
// wsConn is the underlying websocket connection when not in HTTP POST
// mode.
wsConn *websocket.Conn
// httpClient is the underlying HTTP client to use when running in HTTP
// POST mode.
httpClient *http.Client
// mtx is a mutex to protect access to connection related fields.
mtx sync.Mutex
// disconnected indicated whether or not the server is disconnected.
disconnected bool
// retryCount holds the number of times the client has tried to
// reconnect to the RPC server.
retryCount int64
// Track command and their response channels by ID.
requestLock sync.Mutex
requestMap map[uint64]*list.Element
requestList *list.List
// Notifications.
ntfnHandlers *NotificationHandlers
ntfnState *notificationState
// Networking infrastructure.
sendChan chan []byte
sendPostChan chan *sendPostDetails
disconnect chan struct{}
shutdown chan struct{}
wg sync.WaitGroup
}
// NextID returns the next id to be used when sending a JSON-RPC message. This
// ID allows responses to be associated with particular requests per the
// JSON-RPC specification. Typically the consumer of the client does not need
// to call this function, however, if a custom request is being created and used
// this function should be used to ensure the ID is unique amongst all requests
// being made.
func (c *Client) NextID() uint64 {
return atomic.AddUint64(&c.id, 1)
}
// addRequest associates the passed jsonRequest with the passed id. This allows
// the response from the remote server to be unmarshalled to the appropriate
// type and sent to the specified channel when it is received.
//
// This function is safe for concurrent access.
func (c *Client) addRequest(id uint64, request *jsonRequest) {
c.requestLock.Lock()
defer c.requestLock.Unlock()
// TODO(davec): Already there?
element := c.requestList.PushBack(request)
c.requestMap[id] = element
}
// removeRequest returns and removes the jsonRequest which contains the response
// channel and original method associated with the passed id or nil if there is
// no association.
//
// This function is safe for concurrent access.
func (c *Client) removeRequest(id uint64) *jsonRequest {
c.requestLock.Lock()
defer c.requestLock.Unlock()
element := c.requestMap[id]
if element != nil {
delete(c.requestMap, id)
request := c.requestList.Remove(element).(*jsonRequest)
return request
}
return nil
}
// removeAllRequests removes all the jsonRequests which contain the response
// channels for outstanding requests.
//
// This function is safe for concurrent access.
func (c *Client) removeAllRequests() {
c.requestLock.Lock()
defer c.requestLock.Unlock()
c.requestMap = make(map[uint64]*list.Element)
c.requestList.Init()
}
// trackRegisteredNtfns examines the passed command to see if it is one of
// the notification commands and updates the notification state that is used
// to automatically re-establish registered notifications on reconnects.
func (c *Client) trackRegisteredNtfns(cmd btcjson.Cmd) {
// Nothing to do if the caller is not interested in notifications.
if c.ntfnHandlers == nil {
return
}
c.ntfnState.Lock()
defer c.ntfnState.Unlock()
switch bcmd := cmd.(type) {
case *btcws.NotifyBlocksCmd:
c.ntfnState.notifyBlocks = true
case *btcws.NotifyNewTransactionsCmd:
if bcmd.Verbose {
c.ntfnState.notifyNewTxVerbose = true
} else {
c.ntfnState.notifyNewTx = true
}
case *btcws.NotifySpentCmd:
for _, op := range bcmd.OutPoints {
c.ntfnState.notifySpent[op] = struct{}{}
}
case *btcws.NotifyReceivedCmd:
for _, addr := range bcmd.Addresses {
c.ntfnState.notifyReceived[addr] = struct{}{}
}
}
}
// handleMessage is the main handler for incoming requests. It enforces
// authentication, parses the incoming json, looks up and executes handlers
// (including pass through for standard RPC commands), sends the appropriate
// response. It also detects commands which are marked as long-running and
// sends them off to the asyncHander for processing.
func (c *Client) handleMessage(msg []byte) {
// Attempt to unmarshal the message as a known JSON-RPC command.
if cmd, err := btcjson.ParseMarshaledCmd(msg); err == nil {
// Commands that have an ID associated with them are not
// notifications. Since this is a client, it should not
// be receiving non-notifications.
if cmd.Id() != nil {
// Invalid response
log.Warnf("Remote server sent a non-notification "+
"JSON-RPC Request (Id: %v)", cmd.Id())
return
}
// Deliver the notification.
log.Tracef("Received notification [%s]", cmd.Method())
c.handleNotification(cmd)
return
}
// The message was not a command/notification, so it should be a reply
// to a previous request.
var r btcjson.Reply
if err := json.Unmarshal([]byte(msg), &r); err != nil {
log.Warnf("Unable to unmarshal inbound message as " +
"notification or response")
return
}
// Ensure the reply has an id.
if r.Id == nil {
log.Warnf("Received response with no id")
return
}
// Ensure the id is the expected type.
fid, ok := (*r.Id).(float64)
if !ok {
log.Warnf("Received unexpected id type: %T (value %v)",
*r.Id, *r.Id)
return
}
id := uint64(fid)
log.Tracef("Received response for id %d (result %v)", id, r.Result)
request := c.removeRequest(id)
// Nothing more to do if there is no request associated with this reply.
if request == nil || request.responseChan == nil {
log.Warnf("Received unexpected reply: %s (id %d)", r.Result, id)
return
}
// Unmarshal the reply into a concrete result if possible and deliver
// it to the associated channel.
reply, err := btcjson.ReadResultCmd(request.cmd.Method(), []byte(msg))
if err != nil {
log.Warnf("Failed to unmarshal reply to command [%s] "+
"(id %d): %v", request.cmd.Method(), id, err)
request.responseChan <- &futureResult{reply: nil, err: err}
return
}
// Since the command was successful, examine it to see if it's a
// notification, and if is, add it to the notification state so it
// can automatically be re-established on reconnect.
c.trackRegisteredNtfns(request.cmd)
// Deliver the reply.
request.responseChan <- &futureResult{reply: &reply, err: nil}
}
// wsInHandler handles all incoming messages for the websocket connection
// associated with the client. It must be run as a goroutine.
func (c *Client) wsInHandler() {
out:
for {
// Break out of the loop once the shutdown channel has been
// closed. Use a non-blocking select here so we fall through
// otherwise.
select {
case <-c.shutdown:
break out
default:
}
_, msg, err := c.wsConn.ReadMessage()
if err != nil {
// Log the error if it's not due to disconnecting.
if _, ok := err.(*net.OpError); !ok {
log.Errorf("Websocket receive error from "+
"%s: %v", c.config.Host, err)
}
break out
}
c.handleMessage(msg)
}
// Ensure the connection is closed.
c.Disconnect()
c.wg.Done()
log.Tracef("RPC client input handler done for %s", c.config.Host)
}
// wsOutHandler handles all outgoing messages for the websocket connection. It
// uses a buffered channel to serialize output messages while allowing the
// sender to continue running asynchronously. It must be run as a goroutine.
func (c *Client) wsOutHandler() {
out:
for {
// Send any messages ready for send until the client is
// disconnected closed.
select {
case msg := <-c.sendChan:
err := c.wsConn.WriteMessage(websocket.TextMessage, msg)
if err != nil {
c.Disconnect()
break out
}
case <-c.disconnect:
break out
}
}
// Drain any channels before exiting so nothing is left waiting around
// to send.
cleanup:
for {
select {
case <-c.sendChan:
default:
break cleanup
}
}
c.wg.Done()
log.Tracef("RPC client output handler done for %s", c.config.Host)
}
// sendMessage sends the passed JSON to the connected server using the
// websocket connection. It is backed by a buffered channel, so it will not
// block until the send channel is full.
func (c *Client) sendMessage(marshalledJSON []byte) {
// Don't send the message if disconnected.
if c.Disconnected() {
return
}
c.sendChan <- marshalledJSON
}
// reregisterNtfns creates and sends commands needed to re-establish the current
// notification state associated with the client. It should only be called on
// on reconnect by the resendCmds function.
func (c *Client) reregisterNtfns() error {
// Nothing to do if the caller is not interested in notifications.
if c.ntfnHandlers == nil {
return nil
}
// In order to avoid holding the lock on the notification state for the
// entire time of the potentially long running RPCs issued below, make a
// copy of it and work from that.
//
// Also, other commands will be running concurrently which could modify
// the notification state (while not under the lock of course) which
// also register it with the remote RPC server, so this prevents double
// registrations.
stateCopy := c.ntfnState.Copy()
// Reregister notifyblocks if needed.
if stateCopy.notifyBlocks {
log.Debugf("Reregistering [notifyblocks]")
if err := c.NotifyBlocks(); err != nil {
return err
}
}
// Reregister notifynewtransactions if needed.
if stateCopy.notifyNewTx || stateCopy.notifyNewTxVerbose {
log.Debugf("Reregistering [notifynewtransactions] (verbose=%v)",
stateCopy.notifyNewTxVerbose)
err := c.NotifyNewTransactions(stateCopy.notifyNewTxVerbose)
if err != nil {
return err
}
}
// Reregister the combination of all previously registered notifyspent
// outpoints in one command if needed.
nslen := len(stateCopy.notifySpent)
if nslen > 0 {
outpoints := make([]btcws.OutPoint, 0, nslen)
for op := range stateCopy.notifySpent {
outpoints = append(outpoints, op)
}
log.Debugf("Reregistering [notifyspent] outpoints: %v", outpoints)
if err := c.notifySpentInternal(outpoints).Receive(); err != nil {
return err
}
}
// Reregister the combination of all previously registered
// notifyreceived addresses in one command if needed.
nrlen := len(stateCopy.notifyReceived)
if nrlen > 0 {
addresses := make([]string, 0, nrlen)
for addr := range stateCopy.notifyReceived {
addresses = append(addresses, addr)
}
log.Debugf("Reregistering [notifyreceived] addresses: %v", addresses)
if err := c.notifyReceivedInternal(addresses).Receive(); err != nil {
return err
}
}
return nil
}
// resendCmds resends any commands that had not completed when the client
// disconnected. It is intended to be called once the client has reconnected as
// a separate goroutine.
func (c *Client) resendCmds() {
// Set the notification state back up. If anything goes wrong,
// disconnect the client.
if err := c.reregisterNtfns(); err != nil {
log.Warnf("Unable to re-establish notification state: %v", err)
c.Disconnect()
return
}
// Since it's possible to block on send and more commands might be
// added by the caller while resending, make a copy of all of the
// commands that need to be resent now and work from the copy. This
// also allows the lock to be released quickly.
c.requestLock.Lock()
resendCmds := make([]*jsonRequest, 0, c.requestList.Len())
for e := c.requestList.Front(); e != nil; e = e.Next() {
req := e.Value.(*jsonRequest)
resendCmds = append(resendCmds, req)
}
c.requestLock.Unlock()
for _, req := range resendCmds {
// Stop resending commands if the client disconnected again
// since the next reconnect will handle them.
if c.Disconnected() {
return
}
c.marshalAndSend(req.cmd, req.responseChan)
}
}
// wsReconnectHandler listens for client disconnects and automatically tries
// to reconnect with retry interval that scales based on the number of retries.
// It also resends any commands that had not completed when the client
// disconnected so the disconnect/reconnect process is largely transparent to
// the caller. This function is not run when the DisableAutoReconnect config
// options is set.
//
// This function must be run as a goroutine.
func (c *Client) wsReconnectHandler() {
out:
for {
select {
case <-c.disconnect:
// On disconnect, fallthrough to reestablish the
// connection.
case <-c.shutdown:
break out
}
reconnect:
for {
select {
case <-c.shutdown:
break out
default:
}
wsConn, err := dial(c.config)
if err != nil {
c.retryCount++
log.Infof("Failed to connect to %s: %v",
c.config.Host, err)
// Scale the retry interval by the number of
// retries so there is a backoff up to a max
// of 1 minute.
scaledInterval := connectionRetryInterval.Nanoseconds() * c.retryCount
scaledDuration := time.Duration(scaledInterval)
if scaledDuration > time.Minute {
scaledDuration = time.Minute
}
log.Infof("Retrying connection to %s in "+
"%s", c.config.Host, scaledDuration)
time.Sleep(scaledDuration)
continue reconnect
}
log.Infof("Reestablished connection to RPC server %s",
c.config.Host)
// Reset the connection state and signal the reconnect
// has happened.
c.wsConn = wsConn
c.retryCount = 0
c.disconnect = make(chan struct{})
c.mtx.Lock()
c.disconnected = false
c.mtx.Unlock()
// Start processing input and output for the
// new connection.
c.start()
// Reissue pending commands in another goroutine since
// the send can block.
go c.resendCmds()
// Break out of the reconnect loop back to wait for
// disconnect again.
break reconnect
}
}
c.wg.Done()
log.Tracef("RPC client reconnect handler done for %s", c.config.Host)
}
// handleSendPostMessage handles performing the passed HTTP request, reading the
// result, unmarshalling it, and delivering the unmarhsalled result to the
// provided response channel.
func (c *Client) handleSendPostMessage(details *sendPostDetails) {
// Post the request.
cmd := details.command
log.Tracef("Sending command [%s] with id %d", cmd.Method(), cmd.Id())
httpResponse, err := c.httpClient.Do(details.request)
if err != nil {
details.responseChan <- &futureResult{reply: nil, err: err}
return
}
// Read the raw bytes and close the response.
respBytes, err := btcjson.GetRaw(httpResponse.Body)
if err != nil {
details.responseChan <- &futureResult{reply: nil, err: err}
return
}
// Unmarshal the reply into a concrete result if possible.
reply, err := btcjson.ReadResultCmd(cmd.Method(), respBytes)
if err != nil {
details.responseChan <- &futureResult{reply: nil, err: err}
return
}
details.responseChan <- &futureResult{reply: &reply, err: nil}
}
// sendPostHandler handles all outgoing messages when the client is running
// in HTTP POST mode. It uses a buffered channel to serialize output messages
// while allowing the sender to continue running asynchronously. It must be run
// as a goroutine.
func (c *Client) sendPostHandler() {
out:
for {
// Send any messages ready for send until the shutdown channel
// is closed.
select {
case details := <-c.sendPostChan:
c.handleSendPostMessage(details)
case <-c.shutdown:
break out
}
}
// Drain any wait channels before exiting so nothing is left waiting
// around to send.
cleanup:
for {
select {
case details := <-c.sendPostChan:
details.responseChan <- &futureResult{
reply: nil,
err: ErrClientShutdown,
}
default:
break cleanup
}
}
c.wg.Done()
log.Tracef("RPC client send handler done for %s", c.config.Host)
}
// sendPostRequest sends the passed HTTP request to the RPC server using the
// HTTP client associated with the client. It is backed by a buffered channel,
// so it will not block until the send channel is full.
func (c *Client) sendPostRequest(req *http.Request, command btcjson.Cmd, responseChan chan *futureResult) {
// Don't send the message if shutting down.
select {
case <-c.shutdown:
responseChan <- &futureResult{reply: nil, err: ErrClientShutdown}
default:
}
c.sendPostChan <- &sendPostDetails{
request: req,
command: command,
responseChan: responseChan,
}
}
// newFutureError returns a new future result channel that already has the
// passed error waitin on the channel with the reply set to nil. This is useful
// to easily return errors from the various Async functions.
func newFutureError(err error) chan *futureResult {
responseChan := make(chan *futureResult, 1)
responseChan <- &futureResult{err: err}
return responseChan
}
// receiveFuture receives from the passed futureResult channel to extract a
// reply or any errors. The examined errors include an error in the
// futureResult and the error in the reply from the server. This will block
// until the result is available on the passed channel.
func receiveFuture(responseChan chan *futureResult) (interface{}, error) {
// Wait for a response on the returned channel.
response := <-responseChan
if response.err != nil {
return nil, response.err
}
// At this point, the command was either sent to the server and
// there is a response from it, or it is intentionally a nil result
// used to bybass sends for cases such a requesting notifications when
// there are no handlers.
reply := response.reply
if reply == nil {
return nil, nil
}
if reply.Error != nil {
return nil, reply.Error
}
return reply.Result, nil
}
// marshalAndSendPost marshals the passed command to JSON-RPC and sends it to
// the server by issuing an HTTP POST request and returns a response channel
// on which the reply will be delivered. Typically a new connection is opened
// and closed for each command when using this method, however, the underlying
// HTTP client might coalesce multiple commands depending on several factors
// including the remote server configuration.
func (c *Client) marshalAndSendPost(cmd btcjson.Cmd, responseChan chan *futureResult) {
marshalledJSON, err := json.Marshal(cmd)
if err != nil {
responseChan <- &futureResult{reply: nil, err: err}
return
}
// Generate a request to the configured RPC server.
protocol := "http"
if !c.config.DisableTLS {
protocol = "https"
}
url := protocol + "://" + c.config.Host
req, err := http.NewRequest("POST", url, bytes.NewReader(marshalledJSON))
if err != nil {
responseChan <- &futureResult{reply: nil, err: err}
return
}
req.Close = true
req.Header.Set("Content-Type", "application/json")
// Configure basic access authorization.
req.SetBasicAuth(c.config.User, c.config.Pass)
log.Tracef("Sending command [%s] with id %d", cmd.Method(), cmd.Id())
c.sendPostRequest(req, cmd, responseChan)
}
// marshalAndSend marshals the passed command to JSON-RPC and sends it to the
// server. It returns a response channel on which the reply will be delivered.
func (c *Client) marshalAndSend(cmd btcjson.Cmd, responseChan chan *futureResult) {
marshalledJSON, err := json.Marshal(cmd)
if err != nil {
responseChan <- &futureResult{reply: nil, err: err}
return
}
log.Tracef("Sending command [%s] with id %d", cmd.Method(), cmd.Id())
c.sendMessage(marshalledJSON)
}
// sendCmd sends the passed command to the associated server and returns a
// response channel on which the reply will be deliver at some point in the
// future. It handles both websocket and HTTP POST mode depending on the
// configuration of the client.
func (c *Client) sendCmd(cmd btcjson.Cmd) chan *futureResult {
// Choose which marshal and send function to use depending on whether
// the client running in HTTP POST mode or not. When running in HTTP
// POST mode, the command is issued via an HTTP client. Otherwise,
// the command is issued via the asynchronous websocket channels.
responseChan := make(chan *futureResult, 1)
if c.config.HttpPostMode {
c.marshalAndSendPost(cmd, responseChan)
return responseChan
}
c.addRequest(cmd.Id().(uint64), &jsonRequest{
cmd: cmd,
responseChan: responseChan,
})
c.marshalAndSend(cmd, responseChan)
return responseChan
}
// sendCmdAndWait sends the passed command to the associated server, waits
// for the reply, and returns the result from it. It will return the error
// field in the reply if there is one.
func (c *Client) sendCmdAndWait(cmd btcjson.Cmd) (interface{}, error) {
// Marshal the command to JSON-RPC, send it to the connected server, and
// wait for a response on the returned channel.
return receiveFuture(c.sendCmd(cmd))
}
// Disconnected returns whether or not the server is disconnected.
func (c *Client) Disconnected() bool {
c.mtx.Lock()
defer c.mtx.Unlock()
return c.disconnected
}
// Disconnect disconnects the current websocket associated with the client. The
// connection will automatically be re-established unless the client was
// created with the DisableAutoReconnect flag.
//
// This function has no effect when the client is running in HTTP POST mode.
func (c *Client) Disconnect() {
if c.config.HttpPostMode {
return
}
c.mtx.Lock()
defer c.mtx.Unlock()
// Nothing to do if already disconnected.
if c.disconnected {
return
}
log.Tracef("Disconnecting RPC client %s", c.config.Host)
close(c.disconnect)
c.wsConn.Close()
c.disconnected = true
// When operating without auto reconnect, send errors to any pending
// requests and shutdown the client.
if c.config.DisableAutoReconnect {
c.requestLock.Lock()
for e := c.requestList.Front(); e != nil; e = e.Next() {
req := e.Value.(*jsonRequest)
req.responseChan <- &futureResult{
reply: nil,
err: ErrClientDisconnect,
}
}
c.requestLock.Unlock()
c.removeAllRequests()
c.Shutdown()
}
}
// Shutdown shuts down the client by disconnecting any connections associated
// with the client and, when automatic reconnect is enabled, preventing future
// attempts to reconnect. It also stops all goroutines.
func (c *Client) Shutdown() {
// Ignore the shutdown request if the client is already in the process
// of shutting down or already shutdown.
select {
case <-c.shutdown:
return
default:
}
log.Tracef("Shutting down RPC client %s", c.config.Host)
close(c.shutdown)
// Send the ErrClientShutdown error to any pending requests.
c.requestLock.Lock()
for e := c.requestList.Front(); e != nil; e = e.Next() {
req := e.Value.(*jsonRequest)
req.responseChan <- &futureResult{
reply: nil,
err: ErrClientShutdown,
}
}
c.requestLock.Unlock()
c.removeAllRequests()
c.Disconnect()
}
// Start begins processing input and output messages.
func (c *Client) start() {
log.Tracef("Starting RPC client %s", c.config.Host)
// Start the I/O processing handlers depending on whether the client is
// in HTTP POST mode or the default websocket mode.
if c.config.HttpPostMode {
c.wg.Add(1)
go c.sendPostHandler()
} else {
c.wg.Add(2)
go c.wsInHandler()
go c.wsOutHandler()
}
}
// WaitForShutdown blocks until the client goroutines are stopped and the
// connection is closed.
func (c *Client) WaitForShutdown() {
c.wg.Wait()
}
// ConnConfig describes the connection configuration parameters for the client.
// This
type ConnConfig struct {
// Host is the IP address and port of the RPC server you want to connect
// to.
Host string
// Endpoint is the websocket endpoint on the RPC server. This is
// typically "ws" or "frontend".
Endpoint string
// User is the username to use to authenticate to the RPC server.
User string
// Pass is the passphrase to use to authenticate to the RPC server.
Pass string
// DisableTLS specifies whether transport layer security should be
// disabled. It is recommended to always use TLS if the RPC server
// supports it as otherwise your username and password is sent across
// the wire in cleartext.
DisableTLS bool
// Certificates are the bytes for a PEM-encoded certificate chain used
// for the TLS connection. It has no effect if the DisableTLS parameter
// is true.
Certificates []byte
// Proxy specifies to connect through a SOCKS 5 proxy server. It may
// be an empty string if a proxy is not required.
Proxy string
// ProxyUser is an optional username to use for the proxy server if it
// requires authentication. It has no effect if the Proxy parameter
// is not set.
ProxyUser string
// ProxyPass is an optional password to use for the proxy server if it
// requires authentication. It has no effect if the Proxy parameter
// is not set.
ProxyPass string
// DisableAutoReconnect specifies the client should not automatically
// try to reconnect to the server when it has been disconnected.
DisableAutoReconnect bool
// HttpPostMode instructs the client to run using multiple independent
// connections issuing HTTP POST requests instead of using the default
// of websockets. Websockets are generally preferred as some of the
// features of the client such notifications only work with websockets,
// however, not all servers support the websocket extensions, so this
// flag can be set to true to use basic HTTP POST requests instead.
HttpPostMode bool
}
// newHttpClient returns a new http client that is configured according to the
// proxy and TLS settings in the associated connection configuration.
func newHttpClient(config *ConnConfig) (*http.Client, error) {
// Set proxy function if there is a proxy configured.
var proxyFunc func(*http.Request) (*url.URL, error)
if config.Proxy != "" {
proxyURL, err := url.Parse(config.Proxy)
if err != nil {
return nil, err
}
proxyFunc = http.ProxyURL(proxyURL)
}
// Configure TLS if needed.
var tlsConfig *tls.Config
if !config.DisableTLS {
pool := x509.NewCertPool()
pool.AppendCertsFromPEM(config.Certificates)
tlsConfig = &tls.Config{
RootCAs: pool,
}
}
client := http.Client{
Transport: &http.Transport{
Proxy: proxyFunc,
TLSClientConfig: tlsConfig,
},
}
return &client, nil
}
// dial opens a websocket connection using the passed connection configuration
// details.
func dial(config *ConnConfig) (*websocket.Conn, error) {
// Setup TLS if not disabled.
var tlsConfig *tls.Config
var scheme = "ws"
if !config.DisableTLS {
pool := x509.NewCertPool()
pool.AppendCertsFromPEM(config.Certificates)
tlsConfig = &tls.Config{
RootCAs: pool,
MinVersion: tls.VersionTLS12,
}
scheme = "wss"
}
// Create a websocket dialer that will be used to make the connection.
// It is modified by the proxy setting below as needed.
dialer := websocket.Dialer{TLSClientConfig: tlsConfig}
// Setup the proxy if one is configured.
if config.Proxy != "" {
proxy := &socks.Proxy{
Addr: config.Proxy,
Username: config.ProxyUser,
Password: config.ProxyPass,
}
dialer.NetDial = proxy.Dial
}
// The RPC server requires basic authorization, so create a custom
// request header with the Authorization header set.
login := config.User + ":" + config.Pass
auth := "Basic " + base64.StdEncoding.EncodeToString([]byte(login))
requestHeader := make(http.Header)
requestHeader.Add("Authorization", auth)
// Dial the connection.
url := fmt.Sprintf("%s://%s/%s", scheme, config.Host, config.Endpoint)
wsConn, resp, err := dialer.Dial(url, requestHeader)
if err != nil {
if err == websocket.ErrBadHandshake {
// Detect HTTP authentication error status codes.