malformed packet received on agent peer-port crashes agent #259
Description
Describe the bug
The bug happens when random packet received on the peer-port of the kraken-agent, instead of a p2p message from other peers.
When receiving a packet from the peer-port , this code will retrieve the content and validate the msg:
https://github.com/uber/kraken/blob/master/lib/torrent/scheduler/conn/message.go#L126-L144
However, if some malformed packet accidentally passes those 4 checks, and finally constructs an empty p2p.Message struct, the empty msg struct will then go to here:
m.Type checking is fine, since the default value for int32 is 0 - unexpectedly matches this check; but when retrieving m.Bitfield, there would be a nil pointer panic.
To Reproduce
Try to send an empty p2p msg mocking the peer msg
Expected behavior
kraken-agent will panic with nil pointer.
Environments
docker container running on bare metal.
Additional context
panic strack trace:
panic: runtime error: invalid memory address or nil pointer dereference
signal SIGSEGV: segmentation violation code=0x1 addr=0x28 pc=0x8148f8
goroutine 200 [running]:
github.com/uber/kraken/lib/torrent/scheduler/conn.handshakeFromP2PMessage(0xc0004024b0, 0xc00000e1c0, 0x12a05f200, 0xc0004024b0)
/go/src/github.com/uber/kraken/lib/torrent/scheduler/conn/handshaker.go:101 +0x48
github.com/uber/kraken/lib/torrent/scheduler/conn.(*Handshaker).readHandshake(0xc000404280, 0xccbda0, 0xc00000e1c0, 0xc000200c40, 0xc000200cb0, 0xc000200d20)
/go/src/github.com/uber/kraken/lib/torrent/scheduler/conn/handshaker.go:302 +0xe9
github.com/uber/kraken/lib/torrent/scheduler/conn.(*Handshaker).Accept(0xc000404280, 0xccbda0, 0xc00000e1c0, 0xc000201180, 0xc0002011f0, 0xc000201260)
/go/src/github.com/uber/kraken/lib/torrent/scheduler/conn/handshaker.go:228 +0x43
github.com/uber/kraken/lib/torrent/scheduler.(*scheduler).listenLoop.func1(0xc0000e2500, 0xccbda0, 0xc00000e1c0)
/go/src/github.com/uber/kraken/lib/torrent/scheduler/scheduler.go:326 +0x4a
created by github.com/uber/kraken/lib/torrent/scheduler.(*scheduler).listenLoop
/go/src/github.com/uber/kraken/lib/torrent/scheduler/scheduler.go:325 +0x174