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package comms
import (
"encoding/json"
"fmt"
"io"
"io/ioutil"
"net"
"net/http"
"time"
"github.com/ethereum/go-ethereum/logger"
"github.com/ethereum/go-ethereum/logger/glog"
"github.com/ethereum/go-ethereum/rpc/codec"
"github.com/ethereum/go-ethereum/rpc/shared"
)
// When https://github.com/golang/go/issues/4674 is implemented this could be replaced
type stoppableTCPListener struct {
*net.TCPListener
stop chan struct{} // closed when the listener must stop
}
func newStoppableTCPListener(addr string) (*stoppableTCPListener, error) {
wl, err := net.Listen("tcp", addr)
if err != nil {
return nil, err
}
if tcpl, ok := wl.(*net.TCPListener); ok {
stop := make(chan struct{})
return &stoppableTCPListener{tcpl, stop}, nil
}
return nil, fmt.Errorf("Unable to create TCP listener for RPC service")
}
// Stop the listener and all accepted and still active connections.
func (self *stoppableTCPListener) Stop() {
close(self.stop)
}
func (self *stoppableTCPListener) Accept() (net.Conn, error) {
for {
self.SetDeadline(time.Now().Add(time.Duration(1 * time.Second)))
c, err := self.TCPListener.AcceptTCP()
select {
case <-self.stop:
if c != nil { // accept timeout
c.Close()
}
self.TCPListener.Close()
return nil, listenerStoppedError
default:
}
if err != nil {
if netErr, ok := err.(net.Error); ok && netErr.Timeout() && netErr.Temporary() {
continue // regular timeout
}
}
return &closableConnection{c, self.stop}, err
}
}
type closableConnection struct {
*net.TCPConn
closed chan struct{}
}
func (self *closableConnection) Read(b []byte) (n int, err error) {
select {
case <-self.closed:
self.TCPConn.Close()
return 0, io.EOF
default:
return self.TCPConn.Read(b)
}
}
// Wraps the default handler and checks if the RPC service was stopped. In that case it returns an
// error indicating that the service was stopped. This will only happen for connections which are
// kept open (HTTP keep-alive) when the RPC service was shutdown.
func newStoppableHandler(h http.Handler, stop chan struct{}) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
select {
case <-stop:
w.Header().Set("Content-Type", "application/json")
err := fmt.Errorf("RPC service stopped")
response := shared.NewRpcResponse(-1, shared.JsonRpcVersion, nil, err)
httpSend(w, response)
default:
h.ServeHTTP(w, r)
}
})
}
func httpSend(writer io.Writer, v interface{}) (n int, err error) {
var payload []byte
payload, err = json.MarshalIndent(v, "", "\t")
if err != nil {
glog.V(logger.Error).Infoln("Error marshalling JSON", err)
return 0, err
}
glog.V(logger.Detail).Infof("Sending payload: %s", payload)
return writer.Write(payload)
}
func gethHttpHandler(codec codec.Codec, a shared.EthereumApi) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
w.Header().Set("Content-Type", "application/json")
// Limit request size to resist DoS
if req.ContentLength > maxHttpSizeReqLength {
err := fmt.Errorf("Request too large")
response := shared.NewRpcErrorResponse(-1, shared.JsonRpcVersion, -32700, err)
httpSend(w, &response)
return
}
defer req.Body.Close()
payload, err := ioutil.ReadAll(req.Body)
if err != nil {
err := fmt.Errorf("Could not read request body")
response := shared.NewRpcErrorResponse(-1, shared.JsonRpcVersion, -32700, err)
httpSend(w, &response)
return
}
c := codec.New(nil)
var rpcReq shared.Request
if err = c.Decode(payload, &rpcReq); err == nil {
reply, err := a.Execute(&rpcReq)
res := shared.NewRpcResponse(rpcReq.Id, rpcReq.Jsonrpc, reply, err)
httpSend(w, &res)
return
}
var reqBatch []shared.Request
if err = c.Decode(payload, &reqBatch); err == nil {
resBatch := make([]*interface{}, len(reqBatch))
resCount := 0
for i, rpcReq := range reqBatch {
reply, err := a.Execute(&rpcReq)
if rpcReq.Id != nil { // this leaves nil entries in the response batch for later removal
resBatch[i] = shared.NewRpcResponse(rpcReq.Id, rpcReq.Jsonrpc, reply, err)
resCount += 1
}
}
// make response omitting nil entries
resBatch = resBatch[:resCount]
httpSend(w, resBatch)
return
}
// invalid request
err = fmt.Errorf("Could not decode request")
res := shared.NewRpcErrorResponse(-1, shared.JsonRpcVersion, -32600, err)
httpSend(w, res)
})
}
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