// Copyright 2014 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 <http://www.gnu.org/licenses/>.
// Package p2p implements the Ethereum p2p network protocols.
package p2p
import (
"crypto/ecdsa"
"errors"
"fmt"
"net"
"sync"
"time"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/common/mclock"
"github.com/ethereum/go-ethereum/log"
"github.com/ethereum/go-ethereum/p2p/discover"
"github.com/ethereum/go-ethereum/p2p/discv5"
"github.com/ethereum/go-ethereum/p2p/nat"
"github.com/ethereum/go-ethereum/p2p/netutil"
)
const (
defaultDialTimeout = 15 * time.Second
refreshPeersInterval = 30 * time.Second
staticPeerCheckInterval = 15 * time.Second
// Maximum number of concurrently handshaking inbound connections.
maxAcceptConns = 50
// Maximum number of concurrently dialing outbound connections.
maxActiveDialTasks = 16
// Maximum time allowed for reading a complete message.
// This is effectively the amount of time a connection can be idle.
frameReadTimeout = 30 * time.Second
// Maximum amount of time allowed for writing a complete message.
frameWriteTimeout = 20 * time.Second
)
var errServerStopped = errors.New("server stopped")
// Config holds Server options.
type Config struct {
// This field must be set to a valid secp256k1 private key.
PrivateKey *ecdsa.PrivateKey `toml:"-"`
// MaxPeers is the maximum number of peers that can be
// connected. It must be greater than zero.
MaxPeers int
// MaxPendingPeers is the maximum number of peers that can be pending in the
// handshake phase, counted separately for inbound and outbound connections.
// Zero defaults to preset values.
MaxPendingPeers int `toml:",omitempty"`
// NoDiscovery can be used to disable the peer discovery mechanism.
// Disabling is useful for protocol debugging (manual topology).
NoDiscovery bool
// DiscoveryV5 specifies whether the the new topic-discovery based V5 discovery
// protocol should be started or not.
DiscoveryV5 bool `toml:",omitempty"`
// Listener address for the V5 discovery protocol UDP traffic.
DiscoveryV5Addr string `toml:",omitempty"`
// Name sets the node name of this server.
// Use common.MakeName to create a name that follows existing conventions.
Name string `toml:"-"`
// BootstrapNodes are used to establish connectivity
// with the rest of the network.
BootstrapNodes []*discover.Node
// BootstrapNodesV5 are used to establish connectivity
// with the rest of the network using the V5 discovery
// protocol.
BootstrapNodesV5 []*discv5.Node `toml:",omitempty"`
// Static nodes are used as pre-configured connections which are always
// maintained and re-connected on disconnects.
StaticNodes []*discover.Node
// Trusted nodes are used as pre-configured connections which are always
// allowed to connect, even above the peer limit.
TrustedNodes []*discover.Node
// Connectivity can be restricted to certain IP networks.
// If this option is set to a non-nil value, only hosts which match one of the
// IP networks contained in the list are considered.
NetRestrict *netutil.Netlist `toml:",omitempty"`
// NodeDatabase is the path to the database containing the previously seen
// live nodes in the network.
NodeDatabase string `toml:",omitempty"`
// Protocols should contain the protocols supported
// by the server. Matching protocols are launched for
// each peer.
Protocols []Protocol `toml:"-"`
// If ListenAddr is set to a non-nil address, the server
// will listen for incoming connections.
//
// If the port is zero, the operating system will pick a port. The
// ListenAddr field will be updated with the actual address when
// the server is started.
ListenAddr string
// If set to a non-nil value, the given NAT port mapper
// is used to make the listening port available to the
// Internet.
NAT nat.Interface `toml:",omitempty"`
// If Dialer is set to a non-nil value, the given Dialer
// is used to dial outbound peer connections.
Dialer *net.Dialer `toml:"-"`
// If NoDial is true, the server will not dial any peers.
NoDial bool `toml:",omitempty"`
}
// Server manages all peer connections.
type Server struct {
// Config fields may not be modified while the server is running.
Config
// Hooks for testing. These are useful because we can inhibit
// the whole protocol stack.
newTransport func(net.Conn) transport
newPeerHook func(*Peer)
lock sync.Mutex // protects running
running bool
ntab discoverTable
listener net.Listener
ourHandshake *protoHandshake
lastLookup time.Time
DiscV5 *discv5.Network
// These are for Peers, PeerCount (and nothing else).
peerOp chan peerOpFunc
peerOpDone chan struct{}
quit chan struct{}
addstatic chan *discover.Node
removestatic chan *discover.Node
posthandshake chan *conn
addpeer chan *conn
delpeer chan peerDrop
loopWG sync.WaitGroup // loop, listenLoop
}
type peerOpFunc func(map[discover.NodeID]*Peer)
type peerDrop struct {
*Peer
err error
requested bool // true if signaled by the peer
}
type connFlag int
const (
dynDialedConn connFlag = 1 << iota
staticDialedConn
inboundConn
trustedConn
)
// conn wraps a network connection with information gathered
// during the two handshakes.
type conn struct {
fd net.Conn
transport
flags connFlag
cont chan error // The run loop uses cont to signal errors to setupConn.
id discover.NodeID // valid after the encryption handshake
caps []Cap // valid after the protocol handshake
name string // valid after the protocol handshake
}
type transport interface {
// The two handshakes.
doEncHandshake(prv *ecdsa.PrivateKey, dialDest *discover.Node) (discover.NodeID, error)
doProtoHandshake(our *protoHandshake) (*protoHandshake, error)
// The MsgReadWriter can only be used after the encryption
// handshake has completed. The code uses conn.id to track this
// by setting it to a non-nil value after the encryption handshake.
MsgReadWriter
// transports must provide Close because we use MsgPipe in some of
// the tests. Closing the actual network connection doesn't do
// anything in those tests because NsgPipe doesn't use it.
close(err error)
}
func (c *conn) String() string {
s := c.flags.String()
if (c.id != discover.NodeID{}) {
s += " " + c.id.String()
}
s += " " + c.fd.RemoteAddr().String()
return s
}
func (f connFlag) String() string {
s := ""
if f&trustedConn != 0 {
s += "-trusted"
}
if f&dynDialedConn != 0 {
s += "-dyndial"
}
if f&staticDialedConn != 0 {
s += "-staticdial"
}
if f&inboundConn != 0 {
s += "-inbound"
}
if s != "" {
s = s[1:]
}
return s
}
func (c *conn) is(f connFlag) bool {
return c.flags&f != 0
}
// Peers returns all connected peers.
func (srv *Server) Peers() []*Peer {
var ps []*Peer
select {
// Note: We'd love to put this function into a variable but
// that seems to cause a weird compiler error in some
// environments.
case srv.peerOp <- func(peers map[discover.NodeID]*Peer) {
for _, p := range peers {
ps = append(ps, p)
}
}:
<-srv.peerOpDone
case <-srv.quit:
}
return ps
}
// PeerCount returns the number of connected peers.
func (srv *Server) PeerCount() int {
var count int
select {
case srv.peerOp <- func(ps map[discover.NodeID]*Peer) { count = len(ps) }:
<-srv.peerOpDone
case <-srv.quit:
}
return count
}
// AddPeer connects to the given node and maintains the connection until the
// server is shut down. If the connection fails for any reason, the server will
// attempt to reconnect the peer.
func (srv *Server) AddPeer(node *discover.Node) {
select {
case srv.addstatic <- node:
case <-srv.quit:
}
}
// RemovePeer disconnects from the given node
func (srv *Server) RemovePeer(node *discover.Node) {
select {
case srv.removestatic <- node:
case <-srv.quit:
}
}
// Self returns the local node's endpoint information.
func (srv *Server) Self() *discover.Node {
srv.lock.Lock()
defer srv.lock.Unlock()
if !srv.running {
return &discover.Node{IP: net.ParseIP("0.0.0.0")}
}
return srv.makeSelf(srv.listener, srv.ntab)
}
func (srv *Server) makeSelf(listener net.Listener, ntab discoverTable) *discover.Node {
// If the server's not running, return an empty node.
// If the node is running but discovery is off, manually assemble the node infos.
if ntab == nil {
// Inbound connections disabled, use zero address.
if listener == nil {
return &discover.Node{IP: net.ParseIP("0.0.0.0"), ID: discover.PubkeyID(&srv.PrivateKey.PublicKey)}
}
// Otherwise inject the listener address too
addr := listener.Addr().(*net.TCPAddr)
return &discover.Node{
ID: discover.PubkeyID(&srv.PrivateKey.PublicKey),
IP: addr.IP,
TCP: uint16(addr.Port),
}
}
// Otherwise return the discovery node.
return ntab.Self()
}
// Stop terminates the server and all active peer connections.
// It blocks until all active connections have been closed.
func (srv *Server) Stop() {
srv.lock.Lock()
defer srv.lock.Unlock()
if !srv.running {
return
}
srv.running = false
if srv.listener != nil {
// this unblocks listener Accept
srv.listener.Close()
}
close(srv.quit)
srv.loopWG.Wait()
}
// Start starts running the server.
// Servers can not be re-used after stopping.
func (srv *Server) Start() (err error) {
srv.lock.Lock()
defer srv.lock.Unlock()
if srv.running {
return errors.New("server already running")
}
srv.running = true
log.Info("Starting P2P networking")
// static fields
if srv.PrivateKey == nil {
return fmt.Errorf("Server.PrivateKey must be set to a non-nil key")
}
if srv.newTransport == nil {
srv.newTransport = newRLPX
}
if srv.Dialer == nil {
srv.Dialer = &net.Dialer{Timeout: defaultDialTimeout}
}
srv.quit = make(chan struct{})
srv.addpeer = make(chan *conn)
srv.delpeer = make(chan peerDrop)
srv.posthandshake = make(chan *conn)
srv.addstatic = make(chan *discover.Node)
srv.removestatic = make(chan *discover.Node)
srv.peerOp = make(chan peerOpFunc)
srv.peerOpDone = make(chan struct{})
// node table
if !srv.NoDiscovery {
ntab, err := discover.ListenUDP(srv.PrivateKey, srv.ListenAddr, srv.NAT, srv.NodeDatabase, srv.NetRestrict)
if err != nil {
return err
}
if err := ntab.SetFallbackNodes(srv.BootstrapNodes); err != nil {
return err
}
srv.ntab = ntab
}
if srv.DiscoveryV5 {
ntab, err := discv5.ListenUDP(srv.PrivateKey, srv.DiscoveryV5Addr, srv.NAT, "", srv.NetRestrict) //srv.NodeDatabase)
if err != nil {
return err
}
if err := ntab.SetFallbackNodes(srv.BootstrapNodesV5); err != nil {
return err
}
srv.DiscV5 = ntab
}
dynPeers := (srv.MaxPeers + 1) / 2
if srv.NoDiscovery {
dynPeers = 0
}
dialer := newDialState(srv.StaticNodes, srv.BootstrapNodes, srv.ntab, dynPeers, srv.NetRestrict)
// handshake
srv.ourHandshake = &protoHandshake{Version: baseProtocolVersion, Name: srv.Name, ID: discover.PubkeyID(&srv.PrivateKey.PublicKey)}
for _, p := range srv.Protocols {
srv.ourHandshake.Caps = append(srv.ourHandshake.Caps, p.cap())
}
// listen/dial
if srv.ListenAddr != "" {
if err := srv.startListening(); err != nil {
return err
}
}
if srv.NoDial && srv.ListenAddr == "" {
log.Warn("P2P server will be useless, neither dialing nor listening")
}
srv.loopWG.Add(1)
go srv.run(dialer)
srv.running = true
return nil
}
func (srv *Server) startListening() error {
// Launch the TCP listener.
listener, err := net.Listen("tcp", srv.ListenAddr)
if err != nil {
return err
}
laddr := listener.Addr().(*net.TCPAddr)
srv.ListenAddr = laddr.String()
srv.listener = listener
srv.loopWG.Add(1)
go srv.listenLoop()
// Map the TCP listening port if NAT is configured.
if !laddr.IP.IsLoopback() && srv.NAT != nil {
srv.loopWG.Add(1)
go func() {
nat.Map(srv.NAT, srv.quit, "tcp", laddr.Port, laddr.Port, "ethereum p2p")
srv.loopWG.Done()
}()
}
return nil
}
type dialer interface {
newTasks(running int, peers map[discover.NodeID]*Peer, now time.Time) []task
taskDone(task, time.Time)
addStatic(*discover.Node)
removeStatic(*discover.Node)
}
func (srv *Server) run(dialstate dialer) {
defer srv.loopWG.Done()
var (
peers = make(map[discover.NodeID]*Peer)
trusted = make(map[discover.NodeID]bool, len(srv.TrustedNodes))
taskdone = make(chan task, maxActiveDialTasks)
runningTasks []task
queuedTasks []task // tasks that can't run yet
)
// Put trusted nodes into a map to speed up checks.
// Trusted peers are loaded on startup and cannot be
// modified while the server is running.
for _, n := range srv.TrustedNodes {
trusted[n.ID] = true
}
// removes t from runningTasks
delTask := func(t task) {
for i := range runningTasks {
if runningTasks[i] == t {
runningTasks = append(runningTasks[:i], runningTasks[i+1:]...)
break
}
}
}
// starts until max number of active tasks is satisfied
startTasks := func(ts []task) (rest []task) {
i := 0
for ; len(runningTasks) < maxActiveDialTasks && i < len(ts); i++ {
t := ts[i]
log.Trace("New dial task", "task", t)
go func() { t.Do(srv); taskdone <- t }()
runningTasks = append(runningTasks, t)
}
return ts[i:]
}
scheduleTasks := func() {
// Start from queue first.
queuedTasks = append(queuedTasks[:0], startTasks(queuedTasks)...)
// Query dialer for new tasks and start as many as possible now.
if len(runningTasks) < maxActiveDialTasks {
nt := dialstate.newTasks(len(runningTasks)+len(queuedTasks), peers, time.Now())
queuedTasks = append(queuedTasks, startTasks(nt)...)
}
}
running:
for {
scheduleTasks()
select {
case <-srv.quit:
// The server was stopped. Run the cleanup logic.
break running
case n := <-srv.addstatic:
// This channel is used by AddPeer to add to the
// ephemeral static peer list. Add it to the dialer,
// it will keep the node connected.
log.Debug("Adding static node", "node", n)
dialstate.addStatic(n)
case n := <-srv.removestatic:
// This channel is used by RemovePeer to send a
// disconnect request to a peer and begin the
// stop keeping the node connected
log.Debug("Removing static node", "node", n)
dialstate.removeStatic(n)
if p, ok := peers[n.ID]; ok {
p.Disconnect(DiscRequested)
}
case op := <-srv.peerOp:
// This channel is used by Peers and PeerCount.
op(peers)
srv.peerOpDone <- struct{}{}
case t := <-taskdone:
// A task got done. Tell dialstate about it so it
// can update its state and remove it from the active
// tasks list.
log.Trace("Dial task done", "task", t)
dialstate.taskDone(t, time.Now())
delTask(t)
case c := <-srv.posthandshake:
// A connection has passed the encryption handshake so
// the remote identity is known (but hasn't been verified yet).
if trusted[c.id] {
// Ensure that the trusted flag is set before checking against MaxPeers.
c.flags |= trustedConn
}
// TODO: track in-progress inbound node IDs (pre-Peer) to avoid dialing them.
c.cont <- srv.encHandshakeChecks(peers, c)
case c := <-srv.addpeer:
// At this point the connection is past the protocol handshake.
// Its capabilities are known and the remote identity is verified.
err := srv.protoHandshakeChecks(peers, c)
if err == nil {
// The handshakes are done and it passed all checks.
p := newPeer(c, srv.Protocols)
name := truncateName(c.name)
log.Debug("Adding p2p peer", "id", c.id, "name", name, "addr", c.fd.RemoteAddr(), "peers", len(peers)+1)
peers[c.id] = p
go srv.runPeer(p)
}
// The dialer logic relies on the assumption that
// dial tasks complete after the peer has been added or
// discarded. Unblock the task last.
c.cont <- err
case pd := <-srv.delpeer:
// A peer disconnected.
d := common.PrettyDuration(mclock.Now() - pd.created)
pd.log.Debug("Removing p2p peer", "duration", d, "peers", len(peers)-1, "req", pd.requested, "err", pd.err)
delete(peers, pd.ID())
}
}
log.Trace("P2P networking is spinning down")
// Terminate discovery. If there is a running lookup it will terminate soon.
if srv.ntab != nil {
srv.ntab.Close()
}
if srv.DiscV5 != nil {
srv.DiscV5.Close()
}
// Disconnect all peers.
for _, p := range peers {
p.Disconnect(DiscQuitting)
}
// Wait for peers to shut down. Pending connections and tasks are
// not handled here and will terminate soon-ish because srv.quit
// is closed.
for len(peers) > 0 {
p := <-srv.delpeer
p.log.Trace("<-delpeer (spindown)", "remainingTasks", len(runningTasks))
delete(peers, p.ID())
}
}
func (srv *Server) protoHandshakeChecks(peers map[discover.NodeID]*Peer, c *conn) error {
// Drop connections with no matching protocols.
if len(srv.Protocols) > 0 && countMatchingProtocols(srv.Protocols, c.caps) == 0 {
return DiscUselessPeer
}
// Repeat the encryption handshake checks because the
// peer set might have changed between the handshakes.
return srv.encHandshakeChecks(peers, c)
}
func (srv *Server) encHandshakeChecks(peers map[discover.NodeID]*Peer, c *conn) error {
switch {
case !c.is(trustedConn|staticDialedConn) && len(peers) >= srv.MaxPeers:
return DiscTooManyPeers
case peers[c.id] != nil:
return DiscAlreadyConnected
case c.id == srv.Self().ID:
return DiscSelf
default:
return nil
}
}
type tempError interface {
Temporary() bool
}
// listenLoop runs in its own goroutine and accepts
// inbound connections.
func (srv *Server) listenLoop() {
defer srv.loopWG.Done()
log.Info("RLPx listener up", "self", srv.makeSelf(srv.listener, srv.ntab))
// This channel acts as a semaphore limiting
// active inbound connections that are lingering pre-handshake.
// If all slots are taken, no further connections are accepted.
tokens := maxAcceptConns
if srv.MaxPendingPeers > 0 {
tokens = srv.MaxPendingPeers
}
slots := make(chan struct{}, tokens)
for i := 0; i < tokens; i++ {
slots <- struct{}{}
}
for {
// Wait for a handshake slot before accepting.
<-slots
var (
fd net.Conn
err error
)
for {
fd, err = srv.listener.Accept()
if tempErr, ok := err.(tempError); ok && tempErr.Temporary() {
log.Debug("Temporary read error", "err", err)
continue
} else if err != nil {
log.Debug("Read error", "err", err)
return
}
break
}
// Reject connections that do not match NetRestrict.
if srv.NetRestrict != nil {
if tcp, ok := fd.RemoteAddr().(*net.TCPAddr); ok && !srv.NetRestrict.Contains(tcp.IP) {
log.Debug("Rejected conn (not whitelisted in NetRestrict)", "addr", fd.RemoteAddr())
fd.Close()
slots <- struct{}{}
continue
}
}
fd = newMeteredConn(fd, true)
log.Trace("Accepted connection", "addr", fd.RemoteAddr())
// Spawn the handler. It will give the slot back when the connection
// has been established.
go func() {
srv.setupConn(fd, inboundConn, nil)
slots <- struct{}{}
}()
}
}
// setupConn runs the handshakes and attempts to add the connection
// as a peer. It returns when the connection has been added as a peer
// or the handshakes have failed.
func (srv *Server) setupConn(fd net.Conn, flags connFlag, dialDest *discover.Node) {
// Prevent leftover pending conns from entering the handshake.
srv.lock.Lock()
running := srv.running
srv.lock.Unlock()
c := &conn{fd: fd, transport: srv.newTransport(fd), flags: flags, cont: make(chan error)}
if !running {
c.close(errServerStopped)
return
}
// Run the encryption handshake.
var err error
if c.id, err = c.doEncHandshake(srv.PrivateKey, dialDest); err != nil {
log.Trace("Failed RLPx handshake", "addr", c.fd.RemoteAddr(), "conn", c.flags, "err", err)
c.close(err)
return
}
clog := log.New("id", c.id, "addr", c.fd.RemoteAddr(), "conn", c.flags)
// For dialed connections, check that the remote public key matches.
if dialDest != nil && c.id != dialDest.ID {
c.close(DiscUnexpectedIdentity)
clog.Trace("Dialed identity mismatch", "want", c, dialDest.ID)
return
}
if err := srv.checkpoint(c, srv.posthandshake); err != nil {
clog.Trace("Rejected peer before protocol handshake", "err", err)
c.close(err)
return
}
// Run the protocol handshake
phs, err := c.doProtoHandshake(srv.ourHandshake)
if err != nil {
clog.Trace("Failed proto handshake", "err", err)
c.close(err)
return
}
if phs.ID != c.id {
clog.Trace("Wrong devp2p handshake identity", "err", phs.ID)
c.close(DiscUnexpectedIdentity)
return
}
c.caps, c.name = phs.Caps, phs.Name
if err := srv.checkpoint(c, srv.addpeer); err != nil {
clog.Trace("Rejected peer", "err", err)
c.close(err)
return
}
// If the checks completed successfully, runPeer has now been
// launched by run.
}
func truncateName(s string) string {
if len(s) > 20 {
return s[:20] + "..."
}
return s
}
// checkpoint sends the conn to run, which performs the
// post-handshake checks for the stage (posthandshake, addpeer).
func (srv *Server) checkpoint(c *conn, stage chan<- *conn) error {
select {
case stage <- c:
case <-srv.quit:
return errServerStopped
}
select {
case err := <-c.cont:
return err
case <-srv.quit:
return errServerStopped
}
}
// runPeer runs in its own goroutine for each peer.
// it waits until the Peer logic returns and removes
// the peer.
func (srv *Server) runPeer(p *Peer) {
if srv.newPeerHook != nil {
srv.newPeerHook(p)
}
remoteRequested, err := p.run()
// Note: run waits for existing peers to be sent on srv.delpeer
// before returning, so this send should not select on srv.quit.
srv.delpeer <- peerDrop{p, err, remoteRequested}
}
// NodeInfo represents a short summary of the information known about the host.
type NodeInfo struct {
ID string `json:"id"` // Unique node identifier (also the encryption key)
Name string `json:"name"` // Name of the node, including client type, version, OS, custom data
Enode string `json:"enode"` // Enode URL for adding this peer from remote peers
IP string `json:"ip"` // IP address of the node
Ports struct {
Discovery int `json:"discovery"` // UDP listening port for discovery protocol
Listener int `json:"listener"` // TCP listening port for RLPx
} `json:"ports"`
ListenAddr string `json:"listenAddr"`
Protocols map[string]interface{} `json:"protocols"`
}
// NodeInfo gathers and returns a collection of metadata known about the host.
func (srv *Server) NodeInfo() *NodeInfo {
node := srv.Self()
// Gather and assemble the generic node infos
info := &NodeInfo{
Name: srv.Name,
Enode: node.String(),
ID: node.ID.String(),
IP: node.IP.String(),
ListenAddr: srv.ListenAddr,
Protocols: make(map[string]interface{}),
}
info.Ports.Discovery = int(node.UDP)
info.Ports.Listener = int(node.TCP)
// Gather all the running protocol infos (only once per protocol type)
for _, proto := range srv.Protocols {
if _, ok := info.Protocols[proto.Name]; !ok {
nodeInfo := interface{}("unknown")
if query := proto.NodeInfo; query != nil {
nodeInfo = proto.NodeInfo()
}
info.Protocols[proto.Name] = nodeInfo
}
}
return info
}
// PeersInfo returns an array of metadata objects describing connected peers.
func (srv *Server) PeersInfo() []*PeerInfo {
// Gather all the generic and sub-protocol specific infos
infos := make([]*PeerInfo, 0, srv.PeerCount())
for _, peer := range srv.Peers() {
if peer != nil {
infos = append(infos, peer.Info())
}
}
// Sort the result array alphabetically by node identifier
for i := 0; i < len(infos); i++ {
for j := i + 1; j < len(infos); j++ {
if infos[i].ID > infos[j].ID {
infos[i], infos[j] = infos[j], infos[i]
}
}
}
return infos
}
