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server.go
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server.go
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package lrpc
import (
"bytes"
"encoding/binary"
"io"
"net"
"time"
"github.com/centrify/platform-go-sdk/internal/logging"
)
// type lrpc2Server represents a LRPC2 server session. It must implement the MessageServer interface
type lrpc2Server struct {
lrpc2HeaderV4
endpoint string // endpoint information
listener net.Listener // main listener
conn net.Conn // network connection
config *lrpc2SrvConfig // lrpc2 server config
connected bool // flag to show if connected
doneHandShake chan bool // channel for synchronizing handshake
inHandShake bool // state to show whether handshake in progress
handShakeError error // handshake error
}
// lrpc2SrvConfig contains LRPC server configuration
type lrpc2SrvConfig struct {
// LRPC2 server-side timeout when establishing connection (handshake)
ConnectTimeout time.Duration
// LRPC2 server-side timeout when reading data from a client request
ReceiveTimeout time.Duration
// LRPC2 server-side timeout when sending reply back to client
SendTimeout time.Duration
}
func initLrpc2ServerConfig() *lrpc2SrvConfig {
return &lrpc2SrvConfig{
ConnectTimeout: lrpc2ConnectTimeout,
ReceiveTimeout: lrpc2ReceiveTimeout,
SendTimeout: lrpc2SendTimeout,
}
}
// initLrpc2ServerSession init a new LRPC2 server session object.
func initLrpc2ServerSession(endpoint string, config *lrpc2SrvConfig) *lrpc2Server {
s := new(lrpc2Server)
s.magicNum = lrpc2MagicNum
s.headerLen = lrpc2HeaderLengthV4
s.version = lrpc2Version4
s.endpoint = endpoint
s.connected = false
s.config = config
return s
}
// createMessageServer creates a new LRPC2 server session object.
func createMessageServer(endpoint string, acl AccessControlLevel) MessageServer {
var err error
config := initLrpc2ServerConfig()
s := initLrpc2ServerSession(endpoint, config)
if config == nil || s == nil {
logging.Errorf("LRPC Server: Cannot init message server session for endpoint %s", endpoint)
return nil
}
// start listener
s.listener, err = StartListener(s.endpoint, acl)
if err != nil {
// cannot start listener
logging.Errorf("LRPC Server: Cannot create message server session for endpoint %s: %v", endpoint, err)
return nil
}
logging.Debugf("LRPC Server: New message server session [%p] created for endpoint %s", s, endpoint)
return s
}
// Accept() accepts an incoming connection.
// Notes:
// 1. It needs to perform the LRPC handshake
// 2. It returns error if the incoming connection does not completes the handshake. In this case, there is no new
// socket or MessageServer object returned. However, the caller should continue to listen to further requests for
// the same endpoint (i.e., others should still be able to connect to it)
func (s *lrpc2Server) Accept() (MessageServer, error) {
var err error
if s.connected {
return nil, ErrLrpcServerAlreadyConnected
}
// do accept in network layer first
newconn, err := s.listener.Accept()
if err != nil {
if err == io.EOF {
logging.Debug("Connection closed")
}
// cannot accept
return nil, err
}
// clone a new MessageServer object for the new connection
ret := initLrpc2ServerSession(s.endpoint, s.config)
ret.doneHandShake = make(chan bool, 1)
ret.inHandShake = true
ret.conn = newconn
// note: actual handshake is done as a goroutine....
logging.Debugf("LRPC SERVER: accept new connection %p. Network connection %p", ret, newconn)
go ret.doHandShake()
return ret, nil
}
func (s *lrpc2Server) sendBuf(data []interface{}) error {
var err error
buf := new(bytes.Buffer)
// encoding data into byte buffer
for _, v := range data {
err = binary.Write(buf, lrpc2ByteOrder, v)
if err != nil {
logging.Errorf("LRPC SERVER: Failed to write to intermediate buffer: %v", err)
return err
}
}
return write(s.conn, buf.Bytes())
}
func (s *lrpc2Server) replyNACK() error {
data := []interface{}{
uint32(lrpc2Nack),
}
err := s.sendBuf(data)
if err != nil {
logging.Errorf("LRPC SERVER: Error in sending NACK in connection %p: %v", s, err)
}
return err
}
func (s *lrpc2Server) replyACK() error {
data := []interface{}{
uint32(lrpc2Ack),
uint32(lrpc2MaxMsgLen),
}
err := s.sendBuf(data)
if err != nil {
logging.Errorf("LRPC SERVER: Error in sending ACK in connection %p: %v", s, err)
}
return err
}
func (s *lrpc2Server) setHandShakeErr(err error) {
s.inHandShake = false
s.connected = false
s.handShakeError = err
s.doneHandShake <- true // unblocker any potential caller
}
func (s *lrpc2Server) doHandShake() {
var err error
//
// Set timeout
//
// Note that the connection timeout is for the whole handshake. So no
// need to set again for every read/write operation.
now := time.Now()
err = s.conn.SetDeadline(now.Add(s.config.ConnectTimeout))
// NOT sending NACK back if failed to set timeout. Since we cannot
// guarantee the write operation will time out in time. So we do not
// reply to avoid blocking indefinitely. This should be an internal
// error that rarely occurs.
if err != nil {
logging.Infof("Failed to set timeout for LRPC2 connection [%p]: %v", s.conn, err)
return
}
logging.Tracef("LRPC SERVER: Start handshake for server [%p] and connection [%v] with timeout [%v]",
s, s.conn, s.config.ConnectTimeout)
var bytesRequest = make([]byte, lrpc2HandshakeRequestSize)
n, err := read(s.conn, bytesRequest)
if err != nil {
switch t := err.(type) {
case *net.OpError:
if t.Err.Error() == "i/o timeout" || t.Err.Error() == "broken pipe" {
logging.Debugf("LRPC SERVER: Connection not working. Not replying handshake for connection %p. Error: %v",
s, err)
} else {
logging.Debugf("LRPC SERVER: Other connection error for connection %p: %v. Send NACK", s, err)
s.replyNACK()
}
default:
logging.Debugf("LRPC SERVER: Other non-network error for connection %p: %v.", s, err)
}
// update state...
s.setHandShakeErr(err)
return
}
if n != lrpc2HandshakeRequestSize {
logging.Errorf("LRPC SERVER: Handshake request size mismatched. Expect %d, got %d", lrpc2HandshakeRequestSize, n)
s.replyNACK()
// update error status
s.setHandShakeErr(ErrMsgBadHandshakeSize)
return
}
req := bytes.NewBuffer(bytesRequest)
var protocolVersion uint32
err = binary.Read(req, lrpc2ByteOrder, &protocolVersion)
if err != nil {
logging.Errorf("LRPC SERVER: Failed to read LRPC2 protocol version from handshake request for connection %p: %v", s, err)
s.setHandShakeErr(err)
return
}
if protocolVersion != lrpc2Version4 {
logging.Errorf("LRPC SERVER: Unknown LRPC version number for connection %p: %d", s, protocolVersion)
s.replyNACK()
s.setHandShakeErr(ErrMsgBadVersion)
return
}
logging.Tracef("LRPC SERVER: Accept handshake for connection %p. Send ACK", s)
err = s.replyACK()
if err != nil {
logging.Errorf("LRPC SERVER: Error in sending ack for connection %p: %v", s, err)
s.setHandShakeErr(err)
return
}
logging.Tracef("LRPC SERVER: connection %p is ready for requests", s)
// everything is good...update state and return
s.inHandShake = false
s.connected = true
s.doneHandShake <- true
return
}
func (s *lrpc2Server) Close() error {
s.connected = false
if s.listener != nil {
return s.listener.Close()
}
conn := s.conn
if conn != nil {
return conn.Close()
}
return nil
}
func (s *lrpc2Server) GetSessionCtxt() (SessionCtxt, error) {
return NewSessionCtxt(s.conn)
}
func (s *lrpc2Server) IsNamedMessagesSupported() bool {
return false
}
func (s *lrpc2Server) ReadRequest() (interface{}, interface{}, []interface{}, error) {
var err error
var hdr lrpc2HeaderV4 // for handling the received header....
now := time.Now()
err = s.conn.SetDeadline(now.Add(s.config.ReceiveTimeout))
if err != nil {
logging.Infof("Failed to set timeout for LRPC2 connection [%p]: %v", s.conn, err)
return nil, nil, nil, err
}
logging.Tracef("LRPC SERVER: ReadRequest for connection [%p] with timeout [%v]",
s.conn, s.config.ReceiveTimeout)
if s.inHandShake {
// wait for handshake to be done
if s.doneHandShake != nil {
logging.Tracef("LRPC SERVER: Connection %p Waiting for handshake to be done first", s)
<-s.doneHandShake
logging.Tracef("LRPC SERVER: Connection %p Handshake is done", s)
}
if s.handShakeError != nil {
logging.Debugf("LRPC SERVER: Connection %p has handshake error: %v", s, s.handShakeError)
return nil, nil, nil, s.handShakeError
}
}
if !s.connected {
logging.Debugf("LRPC SERVER: Connection %p is not connected.", s)
return nil, nil, nil, ErrLrpcServerNotConnected
}
// good connection....
// read in header first
bytesHeader := make([]byte, s.HeaderLen())
_, err = read(s.conn, bytesHeader)
if err != nil {
if err == io.EOF {
logging.Tracef("LRPC SERVER: Get EOF for connection %p.", s)
} else {
logging.Errorf("LRPC SERVER: Error in reading %d bytes. Connection %p: %v", s.HeaderLen(), s, err)
}
return nil, nil, nil, err
}
logging.Tracef("LRPC SERVER: Got message header for connection %p", s)
msgHdr := bytes.NewBuffer(bytesHeader)
err = hdr.decodeHeader(msgHdr)
if err != nil {
return nil, nil, nil, err
}
err = hdr.verifyHeader()
if err != nil {
logging.Debugf("LRPC SERVER: Cannot verify header for connection %p: %v", s, err)
return nil, nil, nil, err
}
logging.Tracef("LRPC SERVER: Connection %p. Header verified. Try to read %d bytes for message body.", s, hdr.msgDataLen)
bytesMsgData := make([]byte, hdr.msgDataLen)
_, err = read(s.conn, bytesMsgData)
if err != nil {
logging.Debugf("LRPC SERVER: Connection %p. Error in reading %d bytes of message body: %v", s, hdr.msgDataLen, err)
return nil, nil, nil, err
}
msgData := bytes.NewBuffer(bytesMsgData)
cmd, args, err := decode(msgData)
if err != nil {
logging.Debugf("LRPC SERVER: Connection %p. Error in decoding incoming message: %v", s, err)
return nil, nil, nil, err
}
// everything good, save the sequence number, pid and timestamp information from message header
logging.Tracef("LRPC SERVER: Connection %p: Read sequence number: %d", s, hdr.sequenceNum)
return hdr, uint16(cmd), args, nil
}
func (s *lrpc2Server) WriteResponse(msg interface{}, command interface{}, results []interface{}) error {
var err error
now := time.Now()
err = s.conn.SetDeadline(now.Add(s.config.SendTimeout))
if err != nil {
logging.Infof("Failed to set timeout for LRPC2 connection [%p]: %v", s.conn, err)
return err
}
logging.Tracef("LRPC SERVER: WriteResponse to connection [%p] with timeout %v...",
s.conn, s.config.SendTimeout)
if !s.connected {
logging.Debugf("LRPC SERVER: Connection %p is not connected.", s)
return ErrLrpcServerNotConnected
}
hdr, ok := msg.(lrpc2HeaderV4)
if !ok {
logging.Errorf("LRPC SERVER: Wrong message context for connection %p\n", s)
return ErrMsgBadContext
}
cmd, ok := command.(uint16)
if !ok {
logging.Errorf("LRPC SERVER: wrong command type %T. Value: %v\n", command, command)
return ErrMsgBadContext
}
msgData, err := encode(cmd, results)
if err != nil {
logging.Errorf("LRPC SERVER: Connection %p. Error in encoding results: %v", s, err)
return err
}
len := uint32(msgData.Len()) + uint32(s.HeaderLen())
bytesMsg := make([]byte, 0, len)
msgBuf := bytes.NewBuffer(bytesMsg)
// update the header information
s.sequenceNum = hdr.sequenceNum
s.pid = hdr.pid
s.timestamp = uint64(time.Now().Unix())
s.msgDataLen = uint32(msgData.Len())
// encode header
err = s.encodeHeader(msgBuf)
if err != nil {
logging.Errorf("LRPC SERVER: Connection %p. Error in encoding header: %v", s, err)
return err
}
// write data
err = binary.Write(msgBuf, lrpc2ByteOrder, msgData.Bytes())
if err != nil {
logging.Errorf("LRPC SERVER: Connection %p. Error in encoding message data: %v", s, err)
return err
}
// send reply
err = write(s.conn, msgBuf.Bytes())
if err != nil {
logging.Errorf("LRPC SERVER: Connection %p. Error in writing reply to network: %v", s, err)
} else {
logging.Tracef("LRPC SERVER: Connection %p. Reply sent", s)
}
return err
}