Cleaned up error handling in hkexnet.Conn.Read() a bit

This commit is contained in:
Russ Magee 2018-10-30 21:07:42 -07:00
parent e75ed159f6
commit fcbdb77c79
3 changed files with 277 additions and 26 deletions

View file

@ -685,10 +685,8 @@ func (hl *HKExListener) Accept() (hc Conn, err error) {
//
// See go doc io.Reader
func (hc Conn) Read(b []byte) (n int, err error) {
//log.Printf("[Decrypting...]\r\n")
for {
//log.Printf("hc.dBuf.Len(): %d\n", hc.dBuf.Len())
if hc.dBuf.Len() > 0 /* len(b) */ {
if hc.dBuf.Len() > 0 {
break
}
@ -698,31 +696,52 @@ func (hc Conn) Read(b []byte) (n int, err error) {
// Read ctrl/status opcode (CSOHmacInvalid on hmac mismatch)
err = binary.Read(*hc.c, binary.BigEndian, &ctrlStatOp)
if err != nil {
if err.Error() == "EOF" {
return 0, io.EOF
}
if strings.HasSuffix(err.Error(), "use of closed network connection") {
logger.LogNotice(fmt.Sprintln("[Client hung up]"))
return 0, io.EOF
}
etxt := fmt.Sprintf("** Failed read:%s (%s) **", "ctrlStatOp", err)
logger.LogErr(etxt)
return 0, errors.New(etxt)
}
log.Printf("[ctrlStatOp: %v]\n", ctrlStatOp)
if ctrlStatOp == CSOHmacInvalid {
// Other side indicated channel tampering, close channel
hc.Close()
return 1, errors.New("** ALERT - remote end detected HMAC mismatch - possible channel tampering **")
return 0, errors.New("** ALERT - remote end detected HMAC mismatch - possible channel tampering **")
}
// Read the hmac and payload len first
err = binary.Read(*hc.c, binary.BigEndian, &hmacIn)
// Normal client 'exit' from interactive session will cause
// (on server side) err.Error() == "<iface/addr info ...>: use of closed network connection"
if err != nil {
if err == io.EOF || strings.HasSuffix(err.Error(), "use of closed network connection") {
logger.LogNotice(fmt.Sprintln("[Client hung up]"))
} else {
log.Println(err)
if err.Error() == "EOF" {
return 0, io.EOF
}
return 0, err
if strings.HasSuffix(err.Error(), "use of closed network connection") {
logger.LogNotice(fmt.Sprintln("[Client hung up]"))
return 0, io.EOF
}
etxt := fmt.Sprintf("** Failed read:%s (%s) **", "HMAC", err)
logger.LogErr(etxt)
return 0, errors.New(etxt)
}
err = binary.Read(*hc.c, binary.BigEndian, &payloadLen)
if err != nil {
if err.Error() != "EOF" {
logger.LogErr(fmt.Sprintln("[2]unexpected Read() err:", err))
if err.Error() == "EOF" {
return 0, io.EOF
}
if strings.HasSuffix(err.Error(), "use of closed network connection") {
logger.LogNotice(fmt.Sprintln("[Client hung up]"))
return 0, io.EOF
}
etxt := fmt.Sprintf("** Failed read:%s (%s) **", "payloadLen", err)
logger.LogErr(etxt)
return 0, errors.New(etxt)
}
if payloadLen > MAX_PAYLOAD_LEN {
@ -733,15 +752,17 @@ func (hc Conn) Read(b []byte) (n int, err error) {
var payloadBytes = make([]byte, payloadLen)
n, err = io.ReadFull(*hc.c, payloadBytes)
// Normal client 'exit' from interactive session will cause
// (on server side) err.Error() == "<iface/addr info ...>: use of closed network connection"
if err != nil && err.Error() != "EOF" {
if !strings.HasSuffix(err.Error(), "use of closed network connection") {
logger.LogErr(fmt.Sprintln("[3]unexpected Read() err:", err))
} else {
logger.LogNotice(fmt.Sprintln("[Client hung up]"))
if err != nil {
if err.Error() == "EOF" {
return 0, io.EOF
}
if strings.HasSuffix(err.Error(), "use of closed network connection") {
logger.LogNotice(fmt.Sprintln("[Client hung up]"))
return 0, io.EOF
}
etxt := fmt.Sprintf("** Failed read:%s (%s) **", "payloadBytes", err)
logger.LogErr(etxt)
return 0, errors.New(etxt)
}
log.Printf(" <:ctext:\r\n%s\r\n", hex.Dump(payloadBytes[:n]))
@ -797,19 +818,21 @@ func (hc Conn) Read(b []byte) (n int, err error) {
} else if ctrlStatOp == CSOTunData {
lport := binary.BigEndian.Uint16(payloadBytes)
rport := binary.BigEndian.Uint16(payloadBytes[2:4])
fmt.Printf("[Got CSOTunData: [lport %d:rport %d] data:%v\n", lport, rport, payloadBytes[4:])
_ = lport
//fmt.Printf("[Got CSOTunData: [lport %d:rport %d] data:%v\n", lport, rport, payloadBytes[4:])
if hc.tuns[rport] == nil {
fmt.Printf("[Invalid rport:%d]\n", rport)
fmt.Printf("[Invalid rport:%d]\r\n", rport)
} else {
hc.tuns[rport] <- payloadBytes[4:]
}
fmt.Printf("[Done stuffing hc.tuns[rport]\n")
//fmt.Printf("[Done stuffing hc.tuns[rport]\n")
} else if ctrlStatOp == CSOTunClose {
lport := binary.BigEndian.Uint16(payloadBytes)
rport := binary.BigEndian.Uint16(payloadBytes[2:4])
fmt.Printf("[Got CSOTunClose: [lport %d:rport %d]\n", lport, rport)
fmt.Printf("[Got CSOTunClose: [lport %d:rport %d]\r\n", lport, rport)
if hc.tuns[rport] != nil {
close(hc.tuns[rport])
hc.tuns[rport] = nil
}
} else {
hc.dBuf.Write(payloadBytes)

228
hkexnet/hkextun.go Normal file
View file

@ -0,0 +1,228 @@
// hkextun.go - Tunnel setup using an established hkexnet.Conn
// Copyright (c) 2017-2018 Russell Magee
// Licensed under the terms of the MIT license (see LICENSE.mit in this
// distribution)
//
// golang implementation by Russ Magee (rmagee_at_gmail.com)
package hkexnet
import (
"bytes"
"encoding/binary"
"fmt"
"io"
"log"
"net"
"blitter.com/go/hkexsh/logger"
)
type (
// Tunnels
// --
// 1. client is given (lport, remhost, rport) by local user
// 2. client sends [CSOTunReq:rport] to server
// client=> [CSOTunReq:rport] =>remhost
//
// remhost starts worker to receive/send data using rport
// remhost replies to client with rport to acknowledge tun is ready
// client<= [CSOTunAck:rport] <=remhost
// ... or if rhost rport refuses connection, sends
// [CSOTunRefused:rport]
//
// client starts worker to receive/send data using lport
// ... client disconnects: sends remhost [CSOTunClose:rport]
// ... or server disconnects: sends client [CSOTunClose:lport]
// server at any time sends [CSOTunRefused:rport] if daemon died
// --
// TunEndpoint [securePort:peer:dataPort]
TunEndpoint struct {
Rport uint16 // Names are from client's perspective
Lport uint16 // ... ie., RPort is on server, LPort is on client
Peer string //net.Addr
}
TunPacket struct {
n uint32
data []byte
}
)
func startServerTunnel(hc *Conn, lport, rport uint16) {
if hc.tuns == nil {
hc.tuns = make(map[uint16]chan []byte)
}
if hc.tuns[rport] == nil {
hc.tuns[rport] = make(chan []byte, 32)
}
addrs, _ := net.InterfaceAddrs()
t := TunEndpoint{Peer: addrs[0].String(), Lport: lport, Rport: rport}
var resp bytes.Buffer
binary.Write(&resp, binary.BigEndian, t.Lport)
//var dialHangup chan<- bool
c, err := net.Dial("tcp", fmt.Sprintf(":%d", rport))
if err != nil {
logger.LogErr(fmt.Sprintf("Nothing is serving at rport :%d!", rport))
binary.Write(&resp, binary.BigEndian, uint16(0))
// Inform client of the tunPort
hc.WritePacket(resp.Bytes(), CSOTunRefused)
} else {
binary.Write(&resp, binary.BigEndian, t.Rport)
logger.LogNotice(fmt.Sprintf("[Tunnel Opened - %d:%s:%d]", t.Lport, t.Peer, t.Rport))
//
// worker to read data from the rport (to encrypt & send to client)
//
go func() {
defer func() {
//if hc.tuns[rport] != nil {
// close(hc.tuns[rport])
// hc.tuns[rport] = nil
//}
c.Close()
}()
var tunDst bytes.Buffer
binary.Write(&tunDst, binary.BigEndian, t.Lport)
binary.Write(&tunDst, binary.BigEndian, t.Rport)
for {
rBuf := make([]byte, 1024)
// Read data from c, encrypt/write via hc to client(lport)
n, e := c.Read(rBuf)
if e != nil {
if e == io.EOF {
logger.LogNotice(fmt.Sprintf("rport Disconnected: shutting down tunnel %v\n", t))
} else {
logger.LogErr(fmt.Sprintf("Read error from rport of tun %v\n%s", t, e))
}
hc.WritePacket(resp.Bytes(), CSOTunClose)
fmt.Printf("Closing server rport net.Dial()\n")
break
}
if n > 0 {
rBuf = append(tunDst.Bytes(), rBuf[:n]...)
logger.LogNotice(fmt.Sprintf("Got rport data:%v", tunDst.Bytes()))
hc.WritePacket(rBuf[:n+4], CSOTunData)
}
}
}()
// worker to read data from client (already decrypted) & fwd to rport
go func() {
defer func() {
//if hc.tuns[rport] != nil {
//close(hc.tuns[rport])
//hc.tuns[rport] = nil
//}
c.Close()
}()
for {
rData, ok := <-hc.tuns[rport]
if ok {
logger.LogNotice(fmt.Sprintf("Got client data:%v", rData))
c.Write(rData)
} else {
logger.LogErr("!!! ERROR reading from hc.tuns[] channel !!!")
break
}
}
}()
// Inform client of the tunPort
hc.WritePacket(resp.Bytes(), CSOTunAck)
}
}
func StartClientTunnel(hc *Conn, lport, rport uint16) {
go func() {
if hc.tuns == nil {
hc.tuns = make(map[uint16]chan []byte)
}
if hc.tuns[rport] == nil {
hc.tuns[rport] = make(chan []byte, 32)
}
l, e := net.Listen("tcp", fmt.Sprintf(":%d", lport))
if e != nil {
fmt.Printf("[Could not get lport %d! (%s)\n", lport, e)
} else {
defer l.Close()
for {
c, e := l.Accept()
defer func() {
//if hc.tuns[rport] != nil {
// close(hc.tuns[rport])
// hc.tuns[rport] = nil
//}
c.Close()
}()
if e != nil {
log.Printf("Accept() got error(%v), hanging up.\n", e)
break
//log.Fatal(err)
} else {
log.Println("Accepted client")
// outside client -> tunnel lport
go func() {
var tunDst bytes.Buffer
binary.Write(&tunDst, binary.BigEndian, lport)
binary.Write(&tunDst, binary.BigEndian, rport)
for {
rBuf := make([]byte, 1024)
//Read data from c, encrypt/write via hc to client(lport)
n, e := c.Read(rBuf)
if e != nil {
if e == io.EOF {
logger.LogNotice(fmt.Sprintf("lport Disconnected: shutting down tunnel [%d:%d]\n", lport, rport))
} else {
logger.LogErr(fmt.Sprintf("Read error from lport of tun [%d:%d]\n%s", lport, rport, e))
}
hc.WritePacket(tunDst.Bytes(), CSOTunClose)
break
}
if n > 0 {
rBuf = append(tunDst.Bytes(), rBuf[:n]...)
logger.LogNotice(fmt.Sprintf("Got lport data:%v\n", tunDst.Bytes()))
hc.WritePacket(rBuf[:n+4], CSOTunData)
}
}
}()
// tunnel lport -> outside client (c)
go func() {
defer func() {
//if hc.tuns[rport] != nil {
// close(hc.tuns[rport])
// hc.tuns[rport] = nil
//}
c.Close()
}()
for {
//fmt.Printf("Reading from client hc.tuns[%d]\n", lport)
bytes, ok := <-hc.tuns[rport]
if ok {
//fmt.Printf("[Got this through tunnel:%v]\n", bytes)
c.Write(bytes)
} else {
fmt.Printf("[Channel closed? exiting client worker!]\n")
break
}
}
}()
}
}
}
}()
}

View file

@ -352,7 +352,7 @@ func requestTunnel(hc *hkexnet.Conn, lp uint16, p string /*net.Addr*/, rp uint16
errL := binary.Read(hc, binary.BigEndian, &lportReply)
errR := binary.Read(hc, binary.BigEndian, &rportReply)
if errL == nil && errR == nil {
fmt.Printf("Server established tunnel [%d:%d]\n", lportReply, rportReply)
fmt.Printf("Server established tunnel [%d:%d]\r\n", lportReply, rportReply)
hkexnet.StartClientTunnel(hc, lp, rp)
} else {
fmt.Println("FAILED reading remPort")