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server.go
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server.go
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// Copyright (c) 2013-2015 The btcsuite developers
// Copyright (c) 2017-2019 The Hdfchain developers
// Use of this source code is governed by an ISC
// license that can be found in the LICENSE file.
package jsonrpc
import (
"context"
"crypto/sha256"
"crypto/subtle"
"encoding/base64"
"encoding/json"
"io"
"io/ioutil"
"net"
"net/http"
"runtime/trace"
"sync"
"sync/atomic"
"time"
"github.com/hdfchain/hdfwallet/errors"
"github.com/hdfchain/hdfwallet/internal/loader"
"github.com/hdfchain/hdfwallet/rpc/jsonrpc/types"
"github.com/hdfchain/hdfd/chaincfg/v3"
"github.com/hdfchain/hdfd/dcrjson/v3"
hdfdtypes "github.com/hdfchain/hdfd/rpc/jsonrpc/types/v2"
"github.com/gorilla/websocket"
)
type websocketClient struct {
conn *websocket.Conn
authenticated bool
allRequests chan []byte
responses chan []byte
cancel func()
quit chan struct{} // closed on disconnect
wg sync.WaitGroup
}
func newWebsocketClient(c *websocket.Conn, cancel func(), authenticated bool) *websocketClient {
return &websocketClient{
conn: c,
authenticated: authenticated,
allRequests: make(chan []byte),
responses: make(chan []byte),
cancel: cancel,
quit: make(chan struct{}),
}
}
func (c *websocketClient) send(b []byte) error {
select {
case c.responses <- b:
return nil
case <-c.quit:
return errors.New("websocket client disconnected")
}
}
// Server holds the items the RPC server may need to access (auth,
// config, shutdown, etc.)
type Server struct {
httpServer http.Server
walletLoader *loader.Loader
listeners []net.Listener
authsha [sha256.Size]byte
upgrader websocket.Upgrader
cfg Options
wg sync.WaitGroup
quit chan struct{}
quitMtx sync.Mutex
requestShutdownChan chan struct{}
activeNet *chaincfg.Params
}
type handler struct {
fn func(*Server, context.Context, interface{}) (interface{}, error)
noHelp bool
}
// jsonAuthFail sends a message back to the client if the http auth is rejected.
func jsonAuthFail(w http.ResponseWriter) {
w.Header().Add("WWW-Authenticate", `Basic realm="hdfwallet RPC"`)
http.Error(w, "401 Unauthorized.", http.StatusUnauthorized)
}
// NewServer creates a new server for serving JSON-RPC client connections,
// both HTTP POST and websocket.
func NewServer(opts *Options, activeNet *chaincfg.Params, walletLoader *loader.Loader, listeners []net.Listener) *Server {
serveMux := http.NewServeMux()
const rpcAuthTimeoutSeconds = 10
server := &Server{
httpServer: http.Server{
Handler: serveMux,
// Timeout connections which don't complete the initial
// handshake within the allowed timeframe.
ReadTimeout: time.Second * rpcAuthTimeoutSeconds,
},
walletLoader: walletLoader,
cfg: *opts,
listeners: listeners,
// A hash of the HTTP basic auth string is used for a constant
// time comparison.
authsha: sha256.Sum256(httpBasicAuth(opts.Username, opts.Password)),
upgrader: websocket.Upgrader{
// Allow all origins.
CheckOrigin: func(r *http.Request) bool { return true },
},
quit: make(chan struct{}),
requestShutdownChan: make(chan struct{}, 1),
activeNet: activeNet,
}
serveMux.Handle("/", throttledFn(opts.MaxPOSTClients,
func(w http.ResponseWriter, r *http.Request) {
w.Header().Set("Connection", "close")
w.Header().Set("Content-Type", "application/json")
r.Close = true
if err := server.checkAuthHeader(r); err != nil {
log.Warnf("Failed authentication attempt from client %s",
r.RemoteAddr)
jsonAuthFail(w)
return
}
server.wg.Add(1)
defer server.wg.Done()
server.postClientRPC(w, r)
}))
serveMux.Handle("/ws", throttledFn(opts.MaxWebsocketClients,
func(w http.ResponseWriter, r *http.Request) {
authenticated := false
switch server.checkAuthHeader(r) {
case nil:
authenticated = true
case errNoAuth:
// nothing
default:
// If auth was supplied but incorrect, rather than simply
// being missing, immediately terminate the connection.
log.Warnf("Failed authentication attempt from client %s",
r.RemoteAddr)
jsonAuthFail(w)
return
}
conn, err := server.upgrader.Upgrade(w, r, nil)
if err != nil {
log.Warnf("Cannot websocket upgrade client %s: %v",
r.RemoteAddr, err)
return
}
ctx := withRemoteAddr(r.Context(), r.RemoteAddr)
ctx, cancel := context.WithCancel(ctx)
wsc := newWebsocketClient(conn, cancel, authenticated)
server.websocketClientRPC(ctx, wsc)
}))
for _, lis := range listeners {
server.serve(lis)
}
return server
}
// httpBasicAuth returns the UTF-8 bytes of the HTTP Basic authentication
// string:
//
// "Basic " + base64(username + ":" + password)
func httpBasicAuth(username, password string) []byte {
const header = "Basic "
base64 := base64.StdEncoding
b64InputLen := len(username) + len(":") + len(password)
b64Input := make([]byte, 0, b64InputLen)
b64Input = append(b64Input, username...)
b64Input = append(b64Input, ':')
b64Input = append(b64Input, password...)
output := make([]byte, len(header)+base64.EncodedLen(b64InputLen))
copy(output, header)
base64.Encode(output[len(header):], b64Input)
return output
}
// serve serves HTTP POST and websocket RPC for the JSON-RPC RPC server.
// This function does not block on lis.Accept.
func (s *Server) serve(lis net.Listener) {
s.wg.Add(1)
go func() {
defer s.wg.Done()
log.Infof("Listening on %s", lis.Addr())
err := s.httpServer.Serve(lis)
log.Tracef("Finished serving RPC: %v", err)
}()
}
// Stop gracefully shuts down the rpc server by stopping and disconnecting all
// clients. This blocks until shutdown completes.
func (s *Server) Stop() {
s.quitMtx.Lock()
select {
case <-s.quit:
s.quitMtx.Unlock()
return
default:
}
// Stop all the listeners.
for _, listener := range s.listeners {
err := listener.Close()
if err != nil {
log.Errorf("Cannot close listener `%s`: %v",
listener.Addr(), err)
}
}
// Signal the remaining goroutines to stop.
close(s.quit)
s.quitMtx.Unlock()
// Wait for all remaining goroutines to exit.
s.wg.Wait()
}
// handlerClosure creates a closure function for handling requests of the given
// method. This may be a request that is handled directly by hdfwallet, or
// a chain server request that is handled by passing the request down to hdfd.
//
// NOTE: These handlers do not handle special cases, such as the authenticate
// method. Each of these must be checked beforehand (the method is already
// known) and handled accordingly.
func (s *Server) handlerClosure(ctx context.Context, request *dcrjson.Request) lazyHandler {
log.Infof("RPC method %q invoked by %v", request.Method, remoteAddr(ctx))
return lazyApplyHandler(s, ctx, request)
}
// errNoAuth represents an error where authentication could not succeed
// due to a missing Authorization HTTP header.
var errNoAuth = errors.E("missing Authorization header")
// checkAuthHeader checks the HTTP Basic authentication supplied by a client
// in the HTTP request r.
//
// The authentication comparison is time constant.
func (s *Server) checkAuthHeader(r *http.Request) error {
authhdr := r.Header["Authorization"]
if len(authhdr) == 0 {
return errNoAuth
}
authsha := sha256.Sum256([]byte(authhdr[0]))
cmp := subtle.ConstantTimeCompare(authsha[:], s.authsha[:])
if cmp != 1 {
return errors.New("invalid Authorization header")
}
return nil
}
// throttledFn wraps an http.HandlerFunc with throttling of concurrent active
// clients by responding with an HTTP 429 when the threshold is crossed.
func throttledFn(threshold int64, f http.HandlerFunc) http.Handler {
return throttled(threshold, f)
}
// throttled wraps an http.Handler with throttling of concurrent active
// clients by responding with an HTTP 429 when the threshold is crossed.
func throttled(threshold int64, h http.Handler) http.Handler {
var active int64
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
current := atomic.AddInt64(&active, 1)
defer atomic.AddInt64(&active, -1)
if current-1 >= threshold {
log.Warnf("Reached threshold of %d concurrent active clients", threshold)
http.Error(w, "429 Too Many Requests", http.StatusTooManyRequests)
return
}
h.ServeHTTP(w, r)
})
}
// idPointer returns a pointer to the passed ID, or nil if the interface is nil.
// Interface pointers are usually a red flag of doing something incorrectly,
// but this is only implemented here to work around an oddity with dcrjson,
// which uses empty interface pointers for response IDs.
func idPointer(id interface{}) (p *interface{}) {
if id != nil {
p = &id
}
return
}
// invalidAuth checks whether a websocket request is a valid (parsable)
// authenticate request and checks the supplied username and passphrase
// against the server auth.
func (s *Server) invalidAuth(req *dcrjson.Request) bool {
cmd, err := dcrjson.ParseParams(types.Method(req.Method), req.Params)
if err != nil {
return false
}
authCmd, ok := cmd.(*hdfdtypes.AuthenticateCmd)
if !ok {
return false
}
// Check credentials.
login := authCmd.Username + ":" + authCmd.Passphrase
auth := "Basic " + base64.StdEncoding.EncodeToString([]byte(login))
authSha := sha256.Sum256([]byte(auth))
return subtle.ConstantTimeCompare(authSha[:], s.authsha[:]) != 1
}
func (s *Server) websocketClientRead(ctx context.Context, wsc *websocketClient) {
for {
_, request, err := wsc.conn.ReadMessage()
if err != nil {
if !errors.Is(err, io.EOF) && !errors.Is(err, io.ErrUnexpectedEOF) {
log.Warnf("Websocket receive failed from client %s: %v",
remoteAddr(ctx), err)
}
close(wsc.allRequests)
wsc.cancel()
break
}
wsc.allRequests <- request
}
}
func (s *Server) websocketClientRespond(ctx context.Context, wsc *websocketClient) {
// A for-select with a read of the quit channel is used instead of a
// for-range to provide clean shutdown. This is necessary due to
// WebsocketClientRead (which sends to the allRequests chan) not closing
// allRequests during shutdown if the remote websocket client is still
// connected.
out:
for {
select {
case reqBytes, ok := <-wsc.allRequests:
if !ok {
// client disconnected
break out
}
var req dcrjson.Request
err := json.Unmarshal(reqBytes, &req)
if err != nil {
log.Warnf("Failed unmarshal of JSON-RPC request object "+
"from client %s", remoteAddr(ctx))
if !wsc.authenticated {
// Disconnect immediately.
break out
}
resp := makeResponse(req.ID, nil,
dcrjson.ErrRPCInvalidRequest)
mresp, err := json.Marshal(resp)
// We expect the marshal to succeed. If it
// doesn't, it indicates some non-marshalable
// type in the response.
if err != nil {
panic(err)
}
err = wsc.send(mresp)
if err != nil {
break out
}
continue
}
if req.Method == "authenticate" {
log.Infof("RPC method authenticate invoked by %s",
remoteAddr(ctx))
switch {
case wsc.authenticated:
log.Warnf("Multiple authentication attempts from %s",
remoteAddr(ctx))
break out
case s.invalidAuth(&req):
log.Warnf("Failed authentication attempt from %s",
remoteAddr(ctx))
break out
}
wsc.authenticated = true
resp := makeResponse(req.ID, nil, nil)
// Expected to never fail.
mresp, err := json.Marshal(resp)
if err != nil {
panic(err)
}
err = wsc.send(mresp)
if err != nil {
break out
}
continue
}
if !wsc.authenticated {
// Disconnect immediately.
break out
}
switch req.Method {
case "stop":
log.Infof("RPC method stop invoked by %s", remoteAddr(ctx))
resp := makeResponse(req.ID,
"hdfwallet stopping.", nil)
mresp, err := json.Marshal(resp)
// Expected to never fail.
if err != nil {
panic(err)
}
err = wsc.send(mresp)
if err != nil {
break out
}
s.requestProcessShutdown()
break out
default:
req := req // Copy for the closure
ctx, task := trace.NewTask(ctx, req.Method)
f := s.handlerClosure(ctx, &req)
wsc.wg.Add(1)
go func() {
defer task.End()
defer wsc.wg.Done()
resp, jsonErr := f()
mresp, err := dcrjson.MarshalResponse(req.Jsonrpc, req.ID, resp, jsonErr)
if err != nil {
log.Errorf("Unable to marshal response to client %s: %v",
remoteAddr(ctx), err)
} else {
_ = wsc.send(mresp)
}
}()
}
case <-s.quit:
break out
}
}
// allow client to disconnect after all handler goroutines are done
wsc.wg.Wait()
close(wsc.responses)
s.wg.Done()
}
func (s *Server) websocketClientSend(ctx context.Context, wsc *websocketClient) {
defer s.wg.Done()
const deadline time.Duration = 2 * time.Second
out:
for {
select {
case response, ok := <-wsc.responses:
if !ok {
// client disconnected
break out
}
err := wsc.conn.SetWriteDeadline(time.Now().Add(deadline))
if err != nil {
log.Warnf("Cannot set write deadline on "+
"client %s: %v", remoteAddr(ctx), err)
}
err = wsc.conn.WriteMessage(websocket.TextMessage,
response)
if err != nil {
log.Warnf("Failed websocket send to client "+
"%s: %v", remoteAddr(ctx), err)
break out
}
case <-s.quit:
break out
}
}
close(wsc.quit)
log.Infof("Disconnected websocket client %s", remoteAddr(ctx))
}
// websocketClientRPC starts the goroutines to serve JSON-RPC requests over a
// websocket connection for a single client.
func (s *Server) websocketClientRPC(ctx context.Context, wsc *websocketClient) {
log.Infof("New websocket client %s", remoteAddr(ctx))
// Clear the read deadline set before the websocket hijacked
// the connection.
if err := wsc.conn.SetReadDeadline(time.Time{}); err != nil {
log.Warnf("Cannot remove read deadline: %v", err)
}
// WebsocketClientRead is intentionally not run with the waitgroup
// so it is ignored during shutdown. This is to prevent a hang during
// shutdown where the goroutine is blocked on a read of the
// websocket connection if the client is still connected.
go s.websocketClientRead(ctx, wsc)
s.wg.Add(2)
go s.websocketClientRespond(ctx, wsc)
go s.websocketClientSend(ctx, wsc)
<-wsc.quit
}
// maxRequestSize specifies the maximum number of bytes in the request body
// that may be read from a client. This is currently limited to 4MB.
const maxRequestSize = 1024 * 1024 * 4
// postClientRPC processes and replies to a JSON-RPC client request.
func (s *Server) postClientRPC(w http.ResponseWriter, r *http.Request) {
ctx := withRemoteAddr(r.Context(), r.RemoteAddr)
body := http.MaxBytesReader(w, r.Body, maxRequestSize)
rpcRequest, err := ioutil.ReadAll(body)
if err != nil {
// TODO: what if the underlying reader errored?
log.Warnf("Request from client %v exceeds maximum size", r.RemoteAddr)
http.Error(w, "413 Request Too Large.",
http.StatusRequestEntityTooLarge)
return
}
// First check whether wallet has a handler for this request's method.
// If unfound, the request is sent to the chain server for further
// processing. While checking the methods, disallow authenticate
// requests, as they are invalid for HTTP POST clients.
var req dcrjson.Request
err = json.Unmarshal(rpcRequest, &req)
if err != nil {
resp, err := dcrjson.MarshalResponse(req.Jsonrpc, req.ID, nil, dcrjson.ErrRPCInvalidRequest)
if err != nil {
log.Errorf("Unable to marshal response to client %s: %v",
r.RemoteAddr, err)
http.Error(w, "500 Internal Server Error",
http.StatusInternalServerError)
return
}
_, err = w.Write(resp)
if err != nil {
log.Warnf("Cannot write invalid request request to "+
"client %s: %v", r.RemoteAddr, err)
}
return
}
ctx, task := trace.NewTask(ctx, req.Method)
defer task.End()
// Create the response and error from the request. Two special cases
// are handled for the authenticate and stop request methods.
var res interface{}
var jsonErr *dcrjson.RPCError
var stop bool
switch req.Method {
case "authenticate":
log.Warnf("Invalid RPC method authenticate invoked by HTTP POST client %s",
r.RemoteAddr)
// Drop it.
return
case "stop":
log.Infof("RPC method stop invoked by %s", r.RemoteAddr)
stop = true
res = "hdfwallet stopping"
default:
res, jsonErr = s.handlerClosure(ctx, &req)()
}
// Marshal and send.
mresp, err := dcrjson.MarshalResponse(req.Jsonrpc, req.ID, res, jsonErr)
if err != nil {
log.Errorf("Unable to marshal response to client %s: %v",
r.RemoteAddr, err)
http.Error(w, "500 Internal Server Error", http.StatusInternalServerError)
return
}
_, err = w.Write(mresp)
if err != nil {
log.Warnf("Failed to write response to client %s: %v",
r.RemoteAddr, err)
}
if stop {
s.requestProcessShutdown()
}
}
func (s *Server) requestProcessShutdown() {
s.requestShutdownChan <- struct{}{}
}
// RequestProcessShutdown returns a channel that is sent to when an authorized
// client requests remote shutdown.
func (s *Server) RequestProcessShutdown() <-chan struct{} {
return s.requestShutdownChan
}