Peer discovery enhancements/filtering

[lvets]

Hi,

I saw this in my logs today:

INFO:PeerManager:failed connecting to $HOST at SSL port 50002 in 0.5s: [Errno -2] Name or service not known
INFO:PeerManager:failed connecting to $HOST at TCP port 50001 in 0.0s: [Errno -2] Name or service not known
INFO:PeerManager:failed connecting to $HOST at SSL port 50002 in 0.0s: [Errno -2] Name or service not known
INFO:PeerManager:failed connecting to $HOST at TCP port 50001 in 0.0s: [Errno -2] Name or service not known
INFO:PeerManager:forgetting unreachable peer: $HOST
INFO:PeerManager:add_peer request from 45.55.32.24 for $HOST
INFO:PeerManager:failed connecting to $HOST at SSL port 50002 in 0.0s: [Errno -2] Name or service not known
INFO:PeerManager:failed connecting to $HOST at TCP port 50001 in 0.0s: [Errno -2] Name or service not known
INFO:PeerManager:failed connecting to $HOST at SSL port 50002 in 0.0s: [Errno -2] Name or service not known
INFO:PeerManager:failed connecting to $HOST at TCP port 50001 in 0.0s: [Errno -2] Name or service not known
INFO:PeerManager:failed connecting to $HOST at SSL port 50002 in 0.0s: [Errno -2] Name or service not known
INFO:PeerManager:failed connecting to $HOST at TCP port 50001 in 0.0s: [Errno -2] Name or service not known
INFO:PeerManager:forgetting unreachable peer: $HOST
INFO:PeerManager:add_peer request from 84.26.241.153 for $HOST
INFO:PeerManager:failed connecting to $HOST at SSL port 50002 in 0.0s: [Errno -2] Name or service not known
INFO:PeerManager:failed connecting to $HOST at TCP port 50001 in 0.0s: [Errno -2] Name or service not known
INFO:PeerManager:failed connecting to $HOST at SSL port 50002 in 0.0s: [Errno -2] Name or service not known
INFO:PeerManager:failed connecting to $HOST at TCP port 50001 in 0.0s: [Errno -2] Name or service not known
INFO:PeerManager:failed connecting to $HOST at SSL port 50002 in 0.0s: [Errno -2] Name or service not known
INFO:PeerManager:failed connecting to $HOST at TCP port 50001 in 0.0s: [Errno -2] Name or service not known
INFO:PeerManager:forgetting unreachable peer: $HOST

Any chance we can put some sort of filtering in place? For instance, I saw the following invalid peers: "localhost", "$HOST" & "172.19.16.117" (RFC1918 address).

[kyuupichan]

I deliberately decided to accept private addresses thinking someone might be running servers on a private network.

However they are not returned (by recent versions) in the server.peers.subscribe list. We only maintain the peer list to serve it to incoming connections so perhaps accepting them is pointless after all.