bitcoin/bitcoin — pull request #1081 by jgarzik (2012-04-11 16:40:51+00:00)
Title: BIP 0031: pong message

Add a pong message that is sent in reply to a ping. It echoes back a nonce
field that is now added to the ping message. Send a nonce of zero in ping
messages.

Original author: Mike Hearn @ Google

Modified Mike's change to introduce a mild form of protocol documentation in
version.h.