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peers.go
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peers.go
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package gateway
import (
"errors"
"fmt"
"net"
"time"
"github.com/NebulousLabs/Sia/build"
"github.com/NebulousLabs/Sia/encoding"
"github.com/NebulousLabs/Sia/modules"
"github.com/NebulousLabs/Sia/types"
"github.com/NebulousLabs/fastrand"
)
var (
errPeerExists = errors.New("already connected to this peer")
errPeerRejectedConn = errors.New("peer rejected connection")
)
// insufficientVersionError indicates a peer's version is insufficient.
type insufficientVersionError string
// Error implements the error interface for insufficientVersionError.
func (s insufficientVersionError) Error() string {
return "unacceptable version: " + string(s)
}
// invalidVersionError indicates a peer's version is not a valid version number.
type invalidVersionError string
// Error implements the error interface for invalidVersionError.
func (s invalidVersionError) Error() string {
return "invalid version: " + string(s)
}
type peer struct {
modules.Peer
sess streamSession
}
// sessionHeader is sent after the initial version exchange. It prevents peers
// on different blockchains from connecting to each other, and prevents the
// gateway from connecting to itself.
type sessionHeader struct {
GenesisID types.BlockID
UniqueID gatewayID
NetAddress modules.NetAddress
}
func (p *peer) open() (modules.PeerConn, error) {
conn, err := p.sess.Open()
if err != nil {
return nil, err
}
return &peerConn{conn, p.NetAddress}, nil
}
func (p *peer) accept() (modules.PeerConn, error) {
conn, err := p.sess.Accept()
if err != nil {
return nil, err
}
return &peerConn{conn, p.NetAddress}, nil
}
// addPeer adds a peer to the Gateway's peer list, spawns a listener thread to
// handle its requests and increments the remotePeers accordingly
func (g *Gateway) addPeer(p *peer) {
g.peers[p.NetAddress] = p
go g.threadedListenPeer(p)
}
// callInitRPCs calls the rpcs that are registered to be called upon connecting
// to a peer.
func (g *Gateway) callInitRPCs(addr modules.NetAddress) {
for name, fn := range g.initRPCs {
go func(name string, fn modules.RPCFunc) {
if g.threads.Add() != nil {
return
}
defer g.threads.Done()
err := g.managedRPC(addr, name, fn)
if err != nil {
g.log.Debugf("INFO: RPC %q on peer %q failed: %v", name, addr, err)
}
}(name, fn)
}
}
// randomOutboundPeer returns a random outbound peer.
func (g *Gateway) randomOutboundPeer() (modules.NetAddress, error) {
// Get the list of outbound peers.
var addrs []modules.NetAddress
for addr, peer := range g.peers {
if peer.Inbound {
continue
}
addrs = append(addrs, addr)
}
if len(addrs) == 0 {
return "", errNoPeers
}
// Of the remaining options, select one at random.
return addrs[fastrand.Intn(len(addrs))], nil
}
// permanentListen handles incoming connection requests. If the connection is
// accepted, the peer will be added to the Gateway's peer list.
func (g *Gateway) permanentListen(closeChan chan struct{}) {
// Signal that the permanentListen thread has completed upon returning.
defer close(closeChan)
for {
conn, err := g.listener.Accept()
if err != nil {
g.log.Debugln("[PL] Closing permanentListen:", err)
return
}
go g.threadedAcceptConn(conn)
// Sleep after each accept. This limits the rate at which the Gateway
// will accept new connections. The intent here is to prevent new
// incoming connections from kicking out old ones before they have a
// chance to request additional nodes.
select {
case <-time.After(acceptInterval):
case <-g.threads.StopChan():
return
}
}
}
// threadedAcceptConn adds a connecting node as a peer.
func (g *Gateway) threadedAcceptConn(conn net.Conn) {
if g.threads.Add() != nil {
conn.Close()
return
}
defer g.threads.Done()
conn.SetDeadline(time.Now().Add(connStdDeadline))
addr := modules.NetAddress(conn.RemoteAddr().String())
g.log.Debugf("INFO: %v wants to connect", addr)
remoteVersion, err := acceptVersionHandshake(conn, build.Version)
if err != nil {
g.log.Debugf("INFO: %v wanted to connect but version handshake failed: %v", addr, err)
conn.Close()
return
}
if build.VersionCmp(remoteVersion, minimumAcceptablePeerVersion) >= 0 {
err = g.managedAcceptConnPeer(conn, remoteVersion)
} else {
err = errors.New("version number is below threshold")
}
if err != nil {
g.log.Debugf("INFO: %v wanted to connect, but failed: %v", addr, err)
conn.Close()
return
}
// Handshake successful, remove the deadline.
conn.SetDeadline(time.Time{})
g.log.Debugf("INFO: accepted connection from new peer %v (v%v)", addr, remoteVersion)
}
// acceptableSessionHeader returns an error if remoteHeader indicates a peer
// that should not be connected to.
func acceptableSessionHeader(ourHeader, remoteHeader sessionHeader, remoteAddr string) error {
if remoteHeader.GenesisID != ourHeader.GenesisID {
return errPeerGenesisID
} else if remoteHeader.UniqueID == ourHeader.UniqueID {
return errOurAddress
} else if err := remoteHeader.NetAddress.IsStdValid(); err != nil {
return fmt.Errorf("invalid remote address: %v", err)
}
return nil
}
// managedAcceptConnPeer accepts connection requests from peers >= v1.3.1.
// The requesting peer is added as a node and a peer. The peer is only added if
// a nil error is returned.
func (g *Gateway) managedAcceptConnPeer(conn net.Conn, remoteVersion string) error {
g.log.Debugln("Sending sessionHeader with address", g.myAddr, g.myAddr.IsLocal())
// Perform header handshake.
g.mu.RLock()
ourHeader := sessionHeader{
GenesisID: types.GenesisID,
UniqueID: g.staticId,
NetAddress: g.myAddr,
}
g.mu.RUnlock()
remoteHeader, err := exchangeRemoteHeader(conn, ourHeader)
if err != nil {
return err
}
if err := exchangeOurHeader(conn, ourHeader); err != nil {
return err
}
// Get the remote address on which the connecting peer is listening on.
// This means we need to combine the incoming connections ip address with
// the announced open port of the peer.
remoteIP := modules.NetAddress(conn.RemoteAddr().String()).Host()
remotePort := remoteHeader.NetAddress.Port()
remoteAddr := modules.NetAddress(net.JoinHostPort(remoteIP, remotePort))
// Accept the peer.
peer := &peer{
Peer: modules.Peer{
Inbound: true,
// NOTE: local may be true even if the supplied NetAddress is not
// actually reachable.
Local: remoteAddr.IsLocal(),
// Ignoring claimed IP address (which should be == to the socket address)
// by the host but keeping note of the port number so we can call back
NetAddress: remoteAddr,
Version: remoteVersion,
},
sess: newServerStream(conn, remoteVersion),
}
g.mu.Lock()
g.acceptPeer(peer)
g.mu.Unlock()
// Attempt to ping the supplied address. If successful, we will add
// remoteHeader.NetAddress to our node list after accepting the peer. We
// do this in a goroutine so that we can begin communicating with the peer
// immediately.
go func() {
err := g.staticPingNode(remoteAddr)
if err == nil {
g.mu.Lock()
g.addNode(remoteAddr)
g.mu.Unlock()
}
}()
return nil
}
// acceptPeer makes room for the peer if necessary by kicking out existing
// peers, then adds the peer to the peer list.
func (g *Gateway) acceptPeer(p *peer) {
// If we are not fully connected, add the peer without kicking any out.
if len(g.peers) < fullyConnectedThreshold {
g.addPeer(p)
return
}
// Select a peer to kick. Outbound peers and local peers are not
// available to be kicked.
var addrs []modules.NetAddress
for addr, peer := range g.peers {
// Do not kick outbound peers or local peers.
if !peer.Inbound || peer.Local {
continue
}
// Prefer kicking a peer with the same hostname.
if addr.Host() == p.NetAddress.Host() {
addrs = []modules.NetAddress{addr}
break
}
addrs = append(addrs, addr)
}
if len(addrs) == 0 {
// There is nobody suitable to kick, therefore do not kick anyone.
g.addPeer(p)
return
}
// Of the remaining options, select one at random.
kick := addrs[fastrand.Intn(len(addrs))]
g.peers[kick].sess.Close()
delete(g.peers, kick)
g.log.Printf("INFO: disconnected from %v to make room for %v\n", kick, p.NetAddress)
g.addPeer(p)
}
// acceptableVersion returns an error if the version is unacceptable.
func acceptableVersion(version string) error {
if !build.IsVersion(version) {
return invalidVersionError(version)
}
if build.VersionCmp(version, minimumAcceptablePeerVersion) < 0 {
return insufficientVersionError(version)
}
return nil
}
// connectVersionHandshake performs the version handshake and should be called
// on the side making the connection request. The remote version is only
// returned if err == nil.
func connectVersionHandshake(conn net.Conn, version string) (remoteVersion string, err error) {
// Send our version.
if err := encoding.WriteObject(conn, version); err != nil {
return "", fmt.Errorf("failed to write version: %v", err)
}
// Read remote version.
if err := encoding.ReadObject(conn, &remoteVersion, build.MaxEncodedVersionLength); err != nil {
return "", fmt.Errorf("failed to read remote version: %v", err)
}
// Check that their version is acceptable.
if remoteVersion == "reject" {
return "", errPeerRejectedConn
}
if err := acceptableVersion(remoteVersion); err != nil {
return "", err
}
return remoteVersion, nil
}
// acceptVersionHandshake performs the version handshake and should be
// called on the side accepting a connection request. The remote version is
// only returned if err == nil.
func acceptVersionHandshake(conn net.Conn, version string) (remoteVersion string, err error) {
// Read remote version.
if err := encoding.ReadObject(conn, &remoteVersion, build.MaxEncodedVersionLength); err != nil {
return "", fmt.Errorf("failed to read remote version: %v", err)
}
// Check that their version is acceptable.
if err := acceptableVersion(remoteVersion); err != nil {
if err := encoding.WriteObject(conn, "reject"); err != nil {
return "", fmt.Errorf("failed to write reject: %v", err)
}
return "", err
}
// Send our version.
if err := encoding.WriteObject(conn, version); err != nil {
return "", fmt.Errorf("failed to write version: %v", err)
}
return remoteVersion, nil
}
// exchangeOurHeader writes ourHeader and reads the remote's error response.
func exchangeOurHeader(conn net.Conn, ourHeader sessionHeader) error {
// Send our header.
if err := encoding.WriteObject(conn, ourHeader); err != nil {
return fmt.Errorf("failed to write header: %v", err)
}
// Read remote response.
var response string
if err := encoding.ReadObject(conn, &response, 100); err != nil {
return fmt.Errorf("failed to read header acceptance: %v", err)
} else if response == modules.StopResponse {
return errors.New("peer did not want a connection")
} else if response != modules.AcceptResponse {
return fmt.Errorf("peer rejected our header: %v", response)
}
return nil
}
// exchangeRemoteHeader reads the remote header and writes an error response.
func exchangeRemoteHeader(conn net.Conn, ourHeader sessionHeader) (sessionHeader, error) {
// Read remote header.
var remoteHeader sessionHeader
if err := encoding.ReadObject(conn, &remoteHeader, maxEncodedSessionHeaderSize); err != nil {
return sessionHeader{}, fmt.Errorf("failed to read remote header: %v", err)
}
// Validate remote header and write acceptance or rejection.
err := acceptableSessionHeader(ourHeader, remoteHeader, conn.RemoteAddr().String())
if err != nil {
encoding.WriteObject(conn, err.Error()) // error can be ignored
return sessionHeader{}, fmt.Errorf("peer's header was not acceptable: %v", err)
} else if err := encoding.WriteObject(conn, modules.AcceptResponse); err != nil {
return sessionHeader{}, fmt.Errorf("failed to write header acceptance: %v", err)
}
return remoteHeader, nil
}
// managedConnectPeer connects to peers >= v1.3.1. The peer is added as a
// node and a peer. The peer is only added if a nil error is returned.
func (g *Gateway) managedConnectPeer(conn net.Conn, remoteVersion string, remoteAddr modules.NetAddress) error {
g.log.Debugln("Sending sessionHeader with address", g.myAddr, g.myAddr.IsLocal())
// Perform header handshake.
g.mu.RLock()
ourHeader := sessionHeader{
GenesisID: types.GenesisID,
UniqueID: g.staticId,
NetAddress: g.myAddr,
}
g.mu.RUnlock()
if err := exchangeOurHeader(conn, ourHeader); err != nil {
return err
} else if _, err := exchangeRemoteHeader(conn, ourHeader); err != nil {
return err
}
return nil
}
// managedConnect establishes a persistent connection to a peer, and adds it to
// the Gateway's peer list.
func (g *Gateway) managedConnect(addr modules.NetAddress) error {
// Perform verification on the input address.
g.mu.RLock()
gaddr := g.myAddr
g.mu.RUnlock()
if addr == gaddr {
return errors.New("can't connect to our own address")
}
if err := addr.IsStdValid(); err != nil {
return errors.New("can't connect to invalid address")
}
if net.ParseIP(addr.Host()) == nil {
return errors.New("address must be an IP address")
}
g.mu.RLock()
_, exists := g.peers[addr]
g.mu.RUnlock()
if exists {
return errPeerExists
}
// Dial the peer and perform peer initialization.
conn, err := g.staticDial(addr)
if err != nil {
return err
}
// Perform peer initialization.
remoteVersion, err := connectVersionHandshake(conn, build.Version)
if err != nil {
conn.Close()
return err
}
if build.VersionCmp(remoteVersion, minimumAcceptablePeerVersion) >= 0 {
err = g.managedConnectPeer(conn, remoteVersion, addr)
} else {
err = errors.New("version number is below threshold")
}
if err != nil {
conn.Close()
return err
}
// Connection successful, clear the timeout as to maintain a persistent
// connection to this peer.
conn.SetDeadline(time.Time{})
// Add the peer.
g.mu.Lock()
defer g.mu.Unlock()
g.addPeer(&peer{
Peer: modules.Peer{
Inbound: false,
Local: addr.IsLocal(),
NetAddress: addr,
Version: remoteVersion,
},
sess: newClientStream(conn, remoteVersion),
})
g.addNode(addr)
g.nodes[addr].WasOutboundPeer = true
if err := g.saveSync(); err != nil {
g.log.Println("ERROR: Unable to save new outbound peer to gateway:", err)
}
g.log.Debugln("INFO: connected to new peer", addr)
// call initRPCs
g.callInitRPCs(addr)
return nil
}
// Connect establishes a persistent connection to a peer, and adds it to the
// Gateway's peer list.
func (g *Gateway) Connect(addr modules.NetAddress) error {
if err := g.threads.Add(); err != nil {
return err
}
defer g.threads.Done()
return g.managedConnect(addr)
}
// Disconnect terminates a connection to a peer and removes it from the
// Gateway's peer list. The peer's address remains in the node list.
func (g *Gateway) Disconnect(addr modules.NetAddress) error {
if err := g.threads.Add(); err != nil {
return err
}
defer g.threads.Done()
g.mu.RLock()
p, exists := g.peers[addr]
g.mu.RUnlock()
if !exists {
return errors.New("not connected to that node")
}
p.sess.Close()
g.mu.Lock()
// Peer is removed from the peer list as well as the node list, to prevent
// the node from being re-connected while looking for a replacement peer.
delete(g.peers, addr)
delete(g.nodes, addr)
g.mu.Unlock()
g.log.Println("INFO: disconnected from peer", addr)
return nil
}
// Peers returns the addresses currently connected to the Gateway.
func (g *Gateway) Peers() []modules.Peer {
g.mu.RLock()
defer g.mu.RUnlock()
var peers []modules.Peer
for _, p := range g.peers {
peers = append(peers, p.Peer)
}
return peers
}
// Online returns true if the node is connected to the internet. During testing
// we always assume that the node is online
func (g *Gateway) Online() bool {
if build.Release == "dev" || build.Release == "testing" {
return true
}
g.mu.RLock()
defer g.mu.RUnlock()
for _, p := range g.peers {
if !p.Local {
return true
}
}
return false
}