Panic runtime error: slice bounds out of range

[gabstv]

Emitter Server - Docker Image
emitter/server:latest
Digest:sha256:ebd92d6930447120d6746505bb35a434c7c311b26caf53baf31d2d2f5da65baa

2020/02/04 12:42:38 [closing] panic recovered: runtime error: slice bounds out of range [:258] with capacity 3 
 goroutine 1738145 [running]:
runtime/debug.Stack(0xc00067ace8, 0x11387c0, 0xc000039a00)
	/usr/local/go/src/runtime/debug/stack.go:24 +0x9d
github.com/emitter-io/emitter/internal/broker.(*Conn).Close(0xc0026f8600, 0xc002e86b98, 0xc00067af68)
	/go-build/src/github.com/emitter-io/emitter/internal/broker/conn.go:301 +0x243
panic(0x11387c0, 0xc000039a00)
	/usr/local/go/src/runtime/panic.go:679 +0x1b2
github.com/emitter-io/emitter/internal/network/mqtt.readString(...)
	/go-build/src/github.com/emitter-io/emitter/internal/network/mqtt/mqtt.go:857
github.com/emitter-io/emitter/internal/network/mqtt.decodeConnect(0xc003e16804, 0x3, 0x3, 0x3, 0x3)
	/go-build/src/github.com/emitter-io/emitter/internal/network/mqtt/mqtt.go:640 +0x601
github.com/emitter-io/emitter/internal/network/mqtt.DecodePacket(0x13b2e20, 0xc004562fc0, 0x10000, 0x197b680, 0x0, 0x0, 0x197b680)
	/go-build/src/github.com/emitter-io/emitter/internal/network/mqtt/mqtt.go:211 +0x270
github.com/emitter-io/emitter/internal/broker.(*Conn).Process(0xc0026f8600, 0x0, 0x0)
	/go-build/src/github.com/emitter-io/emitter/internal/broker/conn.go:128 +0x1ae
created by github.com/emitter-io/emitter/internal/broker.(*Service).onAcceptConn
	/go-build/src/github.com/emitter-io/emitter/internal/broker/service.go:303 +0x6e

This is probably a minor issue, since the panic is recovered and happens during a connection close.

[kelindar]

Indeed, looks like it received some invalid data. Are you able to consistently reproduce this?

[lzh2nix]

@kelindar when i send an invalid data, just telnet 8080 and send a bad data.

➜  emitter git:(master) ✗ telnet 127.0.0.1 8080
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
10a00100044d51545404c2000a0028363010a00100044d51545404c2000a00283630
Connection closed by foreign host.

and got above like panic

2020/03/02 22:09:27 [closing] panic recovered: runtime error: slice bounds out of range
 goroutine 80 [running]:
runtime/debug.Stack(0xc0003aad38, 0x49e8be0, 0x5374e90)
	/usr/local/go/src/runtime/debug/stack.go:24 +0x9d
github.com/emitter-io/emitter/internal/broker.(*Conn).Close(0xc0002b6880, 0x0, 0x0)
	/Users/lizhengqian/gopath/gocode/src/github.com/emitter-io/emitter/internal/broker/conn.go:301 +0x243
panic(0x49e8be0, 0x5374e90)
	/usr/local/go/src/runtime/panic.go:522 +0x1b5
github.com/emitter-io/emitter/internal/network/mqtt.readString(...)
	/Users/lizhengqian/gopath/gocode/src/github.com/emitter-io/emitter/internal/network/mqtt/mqtt.go:857
github.com/emitter-io/emitter/internal/network/mqtt.decodePublish(0xc0000407e0, 0x30, 0x30, 0x100, 0x30, 0x30)
	/Users/lizhengqian/gopath/gocode/src/github.com/emitter-io/emitter/internal/network/mqtt/mqtt.go:687 +0x202
github.com/emitter-io/emitter/internal/network/mqtt.DecodePacket(0x4d24e40, 0xc0000c3560, 0x10000, 0x5389560, 0x0, 0x0, 0x5389560)
	/Users/lizhengqian/gopath/gocode/src/github.com/emitter-io/emitter/internal/network/mqtt/mqtt.go:215 +0x3eb
github.com/emitter-io/emitter/internal/broker.(*Conn).Process(0xc0002b6880, 0x0, 0x0)
	/Users/lizhengqian/gopath/gocode/src/github.com/emitter-io/emitter/internal/broker/conn.go:128 +0x19a
created by github.com/emitter-io/emitter/internal/broker.(*Service).onAcceptConn
	/Users/lizhengqian/gopath/gocode/src/github.com/emitter-io/emitter/internal/broker/service.go:303 +0x6e

it seemed we should give rdr as parameter to decodexxx, then using rdr.Read() to get data, any good advice?