Optimize UDP packet statistics collection and clear hashstring in Packet::onlySource()

[hy-n]

Hi,

I'm using this in my program on ubuntu, and recently I found that it can not show the pid of udp packets sometimes, then I look up the code carefully, and found it may concerned about the conninode_udp which got from /proc/net/udp, the rem_address in this file is sometimes empty, so the hashstring saved in conninode_udp sometimes may not accurate(only have source address), and when use conninode_udp in getProcess, the value somethimes may could't found, cause the hash key here is the full(which has both source addr and dest addr extracted from the info captured from libpcap), so it was added to the unknownudp; I think its inapposite, maybe use onlySource as key is better here?

Also, I've found that in Packet::onlySource(), the hashstring of new packet is forgot to release.

Hope this helps. Best regards.