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server.go
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/
server.go
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package rpccommon
import (
"bytes"
"encoding/json"
"fmt"
"io"
"net"
"net/rpc"
"net/rpc/jsonrpc"
"os"
"reflect"
"runtime"
"sync"
"unicode"
"unicode/utf8"
"github.com/go-delve/delve/pkg/logflags"
"github.com/go-delve/delve/pkg/version"
"github.com/go-delve/delve/service"
"github.com/go-delve/delve/service/api"
"github.com/go-delve/delve/service/debugger"
"github.com/go-delve/delve/service/rpc1"
"github.com/go-delve/delve/service/rpc2"
"github.com/sirupsen/logrus"
)
// ServerImpl implements a JSON-RPC server that can switch between two
// versions of the API.
type ServerImpl struct {
// config is all the information necessary to start the debugger and server.
config *service.Config
// listener is used to serve HTTP.
listener net.Listener
// stopChan is used to stop the listener goroutine.
stopChan chan struct{}
// debugger is the debugger service.
debugger *debugger.Debugger
// s1 is APIv1 server.
s1 *rpc1.RPCServer
// s2 is APIv2 server.
s2 *rpc2.RPCServer
// maps of served methods, one for each supported API.
methodMaps []map[string]*methodType
log *logrus.Entry
}
type RPCCallback struct {
s *ServerImpl
sending *sync.Mutex
codec rpc.ServerCodec
req rpc.Request
}
// RPCServer implements the RPC method calls common to all versions of the API.
type RPCServer struct {
s *ServerImpl
}
type methodType struct {
method reflect.Method
Rcvr reflect.Value
ArgType reflect.Type
ReplyType reflect.Type
Synchronous bool
}
// NewServer creates a new RPCServer.
func NewServer(config *service.Config) *ServerImpl {
logger := logflags.RPCLogger()
if config.APIVersion < 2 {
logger.Info("Using API v1")
}
if config.Debugger.Foreground {
// Print listener address
logflags.WriteAPIListeningMessage(config.Listener.Addr().String())
logger.Debug("API server pid = ", os.Getpid())
}
return &ServerImpl{
config: config,
listener: config.Listener,
stopChan: make(chan struct{}),
log: logger,
}
}
// Stop stops the JSON-RPC server.
func (s *ServerImpl) Stop() error {
if s.config.AcceptMulti {
close(s.stopChan)
s.listener.Close()
}
kill := s.config.Debugger.AttachPid == 0
return s.debugger.Detach(kill)
}
// Run starts a debugger and exposes it with an HTTP server. The debugger
// itself can be stopped with the `detach` API. Run blocks until the HTTP
// server stops.
func (s *ServerImpl) Run() error {
var err error
if s.config.APIVersion < 2 {
s.config.APIVersion = 1
}
if s.config.APIVersion > 2 {
return fmt.Errorf("unknown API version")
}
// Create and start the debugger
config := s.config.Debugger
if s.debugger, err = debugger.New(&config, s.config.ProcessArgs); err != nil {
return err
}
s.s1 = rpc1.NewServer(s.config, s.debugger)
s.s2 = rpc2.NewServer(s.config, s.debugger)
rpcServer := &RPCServer{s}
s.methodMaps = make([]map[string]*methodType, 2)
s.methodMaps[0] = map[string]*methodType{}
s.methodMaps[1] = map[string]*methodType{}
suitableMethods(s.s1, s.methodMaps[0], s.log)
suitableMethods(rpcServer, s.methodMaps[0], s.log)
suitableMethods(s.s2, s.methodMaps[1], s.log)
suitableMethods(rpcServer, s.methodMaps[1], s.log)
go func() {
defer s.listener.Close()
for {
c, err := s.listener.Accept()
if err != nil {
select {
case <-s.stopChan:
// We were supposed to exit, do nothing and return
return
default:
panic(err)
}
}
if s.config.CheckLocalConnUser {
if !canAccept(s.listener.Addr(), c.RemoteAddr()) {
c.Close()
continue
}
}
go s.serveJSONCodec(c)
if !s.config.AcceptMulti {
break
}
}
}()
return nil
}
// Precompute the reflect type for error. Can't use error directly
// because Typeof takes an empty interface value. This is annoying.
var typeOfError = reflect.TypeOf((*error)(nil)).Elem()
// Is this an exported - upper case - name?
func isExported(name string) bool {
rune, _ := utf8.DecodeRuneInString(name)
return unicode.IsUpper(rune)
}
// Is this type exported or a builtin?
func isExportedOrBuiltinType(t reflect.Type) bool {
for t.Kind() == reflect.Ptr {
t = t.Elem()
}
// PkgPath will be non-empty even for an exported type,
// so we need to check the type name as well.
return isExported(t.Name()) || t.PkgPath() == ""
}
// Fills methods map with the methods of receiver that should be made
// available through the RPC interface.
// These are all the public methods of rcvr that have one of those
// two signatures:
// func (rcvr ReceiverType) Method(in InputType, out *ReplyType) error
// func (rcvr ReceiverType) Method(in InputType, cb service.RPCCallback)
func suitableMethods(rcvr interface{}, methods map[string]*methodType, log *logrus.Entry) {
typ := reflect.TypeOf(rcvr)
rcvrv := reflect.ValueOf(rcvr)
sname := reflect.Indirect(rcvrv).Type().Name()
if sname == "" {
log.Debugf("rpc.Register: no service name for type %s", typ)
return
}
for m := 0; m < typ.NumMethod(); m++ {
method := typ.Method(m)
mname := method.Name
mtype := method.Type
// method must be exported
if method.PkgPath != "" {
continue
}
// Method needs three ins: (receive, *args, *reply) or (receiver, *args, *RPCCallback)
if mtype.NumIn() != 3 {
log.Warn("method", mname, "has wrong number of ins:", mtype.NumIn())
continue
}
// First arg need not be a pointer.
argType := mtype.In(1)
if !isExportedOrBuiltinType(argType) {
log.Warn(mname, "argument type not exported:", argType)
continue
}
replyType := mtype.In(2)
synchronous := replyType.String() != "service.RPCCallback"
if synchronous {
// Second arg must be a pointer.
if replyType.Kind() != reflect.Ptr {
log.Warn("method", mname, "reply type not a pointer:", replyType)
continue
}
// Reply type must be exported.
if !isExportedOrBuiltinType(replyType) {
log.Warn("method", mname, "reply type not exported:", replyType)
continue
}
// Method needs one out.
if mtype.NumOut() != 1 {
log.Warn("method", mname, "has wrong number of outs:", mtype.NumOut())
continue
}
// The return type of the method must be error.
if returnType := mtype.Out(0); returnType != typeOfError {
log.Warn("method", mname, "returns", returnType.String(), "not error")
continue
}
} else {
// Method needs zero outs.
if mtype.NumOut() != 0 {
log.Warn("method", mname, "has wrong number of outs:", mtype.NumOut())
continue
}
}
methods[sname+"."+mname] = &methodType{method: method, ArgType: argType, ReplyType: replyType, Synchronous: synchronous, Rcvr: rcvrv}
}
}
func (s *ServerImpl) serveJSONCodec(conn io.ReadWriteCloser) {
defer func() {
if !s.config.AcceptMulti && s.config.DisconnectChan != nil {
close(s.config.DisconnectChan)
}
}()
sending := new(sync.Mutex)
codec := jsonrpc.NewServerCodec(conn)
var req rpc.Request
var resp rpc.Response
for {
req = rpc.Request{}
err := codec.ReadRequestHeader(&req)
if err != nil {
if err != io.EOF {
s.log.Error("rpc:", err)
}
break
}
mtype, ok := s.methodMaps[s.config.APIVersion-1][req.ServiceMethod]
if !ok {
s.log.Errorf("rpc: can't find method %s", req.ServiceMethod)
s.sendResponse(sending, &req, &rpc.Response{}, nil, codec, fmt.Sprintf("unknown method: %s", req.ServiceMethod))
continue
}
var argv, replyv reflect.Value
// Decode the argument value.
argIsValue := false // if true, need to indirect before calling.
if mtype.ArgType.Kind() == reflect.Ptr {
argv = reflect.New(mtype.ArgType.Elem())
} else {
argv = reflect.New(mtype.ArgType)
argIsValue = true
}
// argv guaranteed to be a pointer now.
if err = codec.ReadRequestBody(argv.Interface()); err != nil {
return
}
if argIsValue {
argv = argv.Elem()
}
if mtype.Synchronous {
if logflags.RPC() {
argvbytes, _ := json.Marshal(argv.Interface())
s.log.Debugf("<- %s(%T%s)", req.ServiceMethod, argv.Interface(), argvbytes)
}
replyv = reflect.New(mtype.ReplyType.Elem())
function := mtype.method.Func
var returnValues []reflect.Value
var errInter interface{}
func() {
defer func() {
if ierr := recover(); ierr != nil {
errInter = newInternalError(ierr, 2)
}
}()
returnValues = function.Call([]reflect.Value{mtype.Rcvr, argv, replyv})
errInter = returnValues[0].Interface()
}()
errmsg := ""
if errInter != nil {
errmsg = errInter.(error).Error()
}
resp = rpc.Response{}
if logflags.RPC() {
replyvbytes, _ := json.Marshal(replyv.Interface())
s.log.Debugf("-> %T%s error: %q", replyv.Interface(), replyvbytes, errmsg)
}
s.sendResponse(sending, &req, &resp, replyv.Interface(), codec, errmsg)
} else {
if logflags.RPC() {
argvbytes, _ := json.Marshal(argv.Interface())
s.log.Debugf("(async %d) <- %s(%T%s)", req.Seq, req.ServiceMethod, argv.Interface(), argvbytes)
}
function := mtype.method.Func
ctl := &RPCCallback{s, sending, codec, req}
go func() {
defer func() {
if ierr := recover(); ierr != nil {
ctl.Return(nil, newInternalError(ierr, 2))
}
}()
function.Call([]reflect.Value{mtype.Rcvr, argv, reflect.ValueOf(ctl)})
}()
}
}
codec.Close()
}
// A value sent as a placeholder for the server's response value when the server
// receives an invalid request. It is never decoded by the client since the Response
// contains an error when it is used.
var invalidRequest = struct{}{}
func (s *ServerImpl) sendResponse(sending *sync.Mutex, req *rpc.Request, resp *rpc.Response, reply interface{}, codec rpc.ServerCodec, errmsg string) {
resp.ServiceMethod = req.ServiceMethod
if errmsg != "" {
resp.Error = errmsg
reply = invalidRequest
}
resp.Seq = req.Seq
sending.Lock()
defer sending.Unlock()
err := codec.WriteResponse(resp, reply)
if err != nil {
s.log.Error("writing response:", err)
}
}
func (cb *RPCCallback) Return(out interface{}, err error) {
errmsg := ""
if err != nil {
errmsg = err.Error()
}
var resp rpc.Response
if logflags.RPC() {
outbytes, _ := json.Marshal(out)
cb.s.log.Debugf("(async %d) -> %T%s error: %q", cb.req.Seq, out, outbytes, errmsg)
}
cb.s.sendResponse(cb.sending, &cb.req, &resp, out, cb.codec, errmsg)
}
// GetVersion returns the version of delve as well as the API version
// currently served.
func (s *RPCServer) GetVersion(args api.GetVersionIn, out *api.GetVersionOut) error {
out.DelveVersion = version.DelveVersion.String()
out.APIVersion = s.s.config.APIVersion
return s.s.debugger.GetVersion(out)
}
// Changes version of the API being served.
func (s *RPCServer) SetApiVersion(args api.SetAPIVersionIn, out *api.SetAPIVersionOut) error {
if args.APIVersion < 2 {
args.APIVersion = 1
}
if args.APIVersion > 2 {
return fmt.Errorf("unknown API version")
}
s.s.config.APIVersion = args.APIVersion
return nil
}
type internalError struct {
Err interface{}
Stack []internalErrorFrame
}
type internalErrorFrame struct {
Pc uintptr
Func string
File string
Line int
}
func newInternalError(ierr interface{}, skip int) *internalError {
r := &internalError{ierr, nil}
for i := skip; ; i++ {
pc, file, line, ok := runtime.Caller(i)
if !ok {
break
}
fname := "<unknown>"
fn := runtime.FuncForPC(pc)
if fn != nil {
fname = fn.Name()
}
r.Stack = append(r.Stack, internalErrorFrame{pc, fname, file, line})
}
return r
}
func (err *internalError) Error() string {
var out bytes.Buffer
fmt.Fprintf(&out, "Internal debugger error: %v\n", err.Err)
for _, frame := range err.Stack {
fmt.Fprintf(&out, "%s (%#x)\n\t%s:%d\n", frame.Func, frame.Pc, frame.File, frame.Line)
}
return out.String()
}