Restart fails: UDP socket reuse

[ebuchman]

I'm writing a little wrapper to make it easier to use ipfs as a library.

I've been having trouble restarting the node due to socket reuse problems with the utp socket. I noticed the SO_REUSE opts commented out in net/swarm/conn.go, but it seems to have no problem reusing the TCP connection, so I'm especially surprised there's a problem reusing the UDP. I have confirmed the socket indeed remains open while the TCP connection is closed (using lsof -i) even after the log (below) indicates it's been closed.

21:35:04.003  INFO       conn: listener closing: [Peer Qme5epCPhcKA] /ip4/0.0.0.0/tcp/4001 listen.go:47
21:35:04.003 DEBUG       conn: [Peer Qme5epCPhcKA] closing Conn with [Peer QmaCpDMGvV2B] multiconn.go:216
21:35:04.003  INFO       conn: listener closing: [Peer Qme5epCPhcKA] /ip4/0.0.0.0/udp/4002/utp listen.go:47
21:35:04.003 DEBUG       conn: [Peer Qme5epCPhcKA] closing Conn with [Peer QmaCpDMGvV2B] conn.go:115
2014/11/27 21:35:09 restarting...
21:35:09.753  INFO      swarm: InterfaceListenAddresses:[/ip6/fe80::4e8d:79ff:fedb:fd72/tcp/4001 /ip4/192.168.1.140/tcp/4001] addrs.go:64
21:35:09.753  INFO      swarm: InterfaceListenAddresses:[/ip6/fe80::4e8d:79ff:fedb:fd72/udp/4002/utp /ip4/192.168.1.140/udp/4002/utp] addrs.go:64
21:35:09.753 ERROR      swarm: Failed to listen on: /ip4/0.0.0.0/udp/4002/utp - Failed to listen on /ip4/0.0.0.0/udp/4002/utp: listen udp 0.0.0.0:4002: bind: address already in use conn.go:28
21:35:09.753  INFO       conn: swarm listening on /ip4/0.0.0.0/tcp/4001 -- &{0xc20803c070 0xc208206d80}
 listen.go:78
2014/11/27 21:35:09 1: Failed to listen on /ip4/0.0.0.0/udp/4002/utp: listen udp 0.0.0.0:4002: bind: address already in use

[jbenet]

Oh, this is interesting. thanks for finding this. It's possible this is due to how the utp lib works. I'll take a look at this in the next few days. cc @anacrolix as he may be interested.

[jbenet]

@ebuchman i imagine this is a bug in h2so5/utp or jbenet/go-multiaddr-net. it shouldn't be in master as of #490 (merging shortly). Depending on what other udp transport we use (#58), this may or may not resurce. closing for now.