From ebfc3388143d848007a66bf12c46c45b62a5f77c Mon Sep 17 00:00:00 2001 From: Felix Lange Date: Thu, 10 Dec 2015 14:11:33 +0100 Subject: [PATCH] p2p: add connectivity docs and protocol-level Prefer channel --- p2p/doc.go | 61 +++++++++++++++++++++++++++++++++++++++++++++++++ p2p/protocol.go | 22 ++++++++++++------ p2p/server.go | 1 - 3 files changed, 76 insertions(+), 8 deletions(-) create mode 100644 p2p/doc.go diff --git a/p2p/doc.go b/p2p/doc.go new file mode 100644 index 0000000000..a89a2d3122 --- /dev/null +++ b/p2p/doc.go @@ -0,0 +1,61 @@ +// Copyright 2015 The go-ethereum Authors +// This file is part of the go-ethereum library. +// +// The go-ethereum library is free software: you can redistribute it and/or modify +// it under the terms of the GNU Lesser General Public License as published by +// the Free Software Foundation, either version 3 of the License, or +// (at your option) any later version. +// +// The go-ethereum library is distributed in the hope that it will be useful, +// but WITHOUT ANY WARRANTY; without even the implied warranty of +// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +// GNU Lesser General Public License for more details. +// +// You should have received a copy of the GNU Lesser General Public License +// along with the go-ethereum library. If not, see . + +/* +Package p2p implements the devp2p protocol suite. + +The devp2p suite is a framework for the definition of RLP-based +peer-to-peer protocols. + +From Nodes to Peers and Protocols + +Devp2p distinguishes nodes and peers. A node is any devp2p-capable +host participating in the network. Peers are nodes to which a +connection has been established. Nodes are identified by their Node +ID, a secp256k1 public key. + +On any particular connection, one or more protocols are spoken. The +protocols understood by the local node are declared when creating the +local Server. When the connection is established, the sets of +available protocols are matched against each other and the Run +function of each protocol present on both sides is launched. + +RLPx + +Connections between peers use the RLPx wire protocol, which provides +an encrypted and authenticated communication channel over TCP. RLPx +supports concurrent transfer of protocol messages, ensuring that all +protocols get an equal share of the available bandwidth. + +Connection Handling + +Package p2p establishes peer connections automatically by selecting +randomly from the pool of all existing nodes in the network. The +connectivity graph approaches an unstructured network with low +diameter. If a protocol requires stronger connectivity properties +(e.g. when building a structured overlay), the protocol implementation +should provide information about preferred nodes on its Prefer channel. + +In order to accomodate new nodes joining the network, non-preferred +peer connections may be terminated under certain conditions. Protocol +implementations are free to terminate connections at any time by +simply returning from the Run function. + +Users can configure static connectivity targets through the AddPeer +method of Server. It will attempt to keep such nodes connected at all +times. +*/ +package p2p diff --git a/p2p/protocol.go b/p2p/protocol.go index ee747ba23d..db4125b83b 100644 --- a/p2p/protocol.go +++ b/p2p/protocol.go @@ -35,22 +35,30 @@ type Protocol struct { // by the protocol. Length uint64 - // Run is called in a new groutine when the protocol has been + // Run is called in a new goroutine when the protocol has been // negotiated with a peer. It should read and write messages from // rw. The Payload for each message must be fully consumed. // - // The peer connection is closed when Start returns. It should return + // The peer connection is closed when Run returns. It should return // any protocol-level error (such as an I/O error) that is // encountered. Run func(peer *Peer, rw MsgReadWriter) error - // NodeInfo is an optional helper method to retrieve protocol specific metadata - // about the host node. + // Prefer, if non-nil, should receive nodes that the protocol + // implementation wants to be connected to. If a preferred node is + // not connected yet, package p2p will attempt to establish a + // connection. A successful send on this channel does not + // guarantee that a connection will actually be established. + Prefer <-chan *discover.Node + + // NodeInfo is an optional helper method to retrieve protocol + // specific metadata about the host node. NodeInfo func() interface{} - // PeerInfo is an optional helper method to retrieve protocol specific metadata - // about a certain peer in the network. If an info retrieval function is set, - // but returns nil, it is assumed that the protocol handshake is still running. + // PeerInfo is an optional helper method to retrieve protocol + // specific metadata about a certain peer in the network. If an + // info retrieval function is set, but returns nil, it is assumed + // that the protocol handshake is still running. PeerInfo func(id discover.NodeID) interface{} } diff --git a/p2p/server.go b/p2p/server.go index 7991585f17..d94d37201c 100644 --- a/p2p/server.go +++ b/p2p/server.go @@ -14,7 +14,6 @@ // You should have received a copy of the GNU Lesser General Public License // along with the go-ethereum library. If not, see . -// Package p2p implements the Ethereum p2p network protocols. package p2p import (