lotus/chain/exchange/client.go
2022-06-14 17:00:51 +02:00

494 lines
15 KiB
Go

package exchange
import (
"bufio"
"context"
"fmt"
"math/rand"
"time"
"github.com/libp2p/go-libp2p-core/host"
"github.com/libp2p/go-libp2p-core/network"
"github.com/libp2p/go-libp2p-core/peer"
"go.opencensus.io/trace"
"go.uber.org/fx"
"golang.org/x/xerrors"
cborutil "github.com/filecoin-project/go-cbor-util"
"github.com/filecoin-project/lotus/build"
"github.com/filecoin-project/lotus/chain/store"
"github.com/filecoin-project/lotus/chain/types"
incrt "github.com/filecoin-project/lotus/lib/increadtimeout"
"github.com/filecoin-project/lotus/lib/peermgr"
)
// client implements exchange.Client, using the libp2p ChainExchange protocol
// as the fetching mechanism.
type client struct {
// Connection manager used to contact the server.
// FIXME: We should have a reduced interface here, initialized
// just with our protocol ID, we shouldn't be able to open *any*
// connection.
host host.Host
peerTracker *bsPeerTracker
}
var _ Client = (*client)(nil)
// NewClient creates a new libp2p-based exchange.Client that uses the libp2p
// ChainExhange protocol as the fetching mechanism.
func NewClient(lc fx.Lifecycle, host host.Host, pmgr peermgr.MaybePeerMgr) Client {
return &client{
host: host,
peerTracker: newPeerTracker(lc, host, pmgr.Mgr),
}
}
// Main logic of the client request service. The provided `Request`
// is sent to the `singlePeer` if one is indicated or to all available
// ones otherwise. The response is processed and validated according
// to the `Request` options. Either a `validatedResponse` is returned
// (which can be safely accessed), or an `error` that may represent
// either a response error status, a failed validation or an internal
// error.
//
// This is the internal single point of entry for all external-facing
// APIs, currently we have 3 very heterogeneous services exposed:
// * GetBlocks: Headers
// * GetFullTipSet: Headers | Messages
// * GetChainMessages: Messages
// This function handles all the different combinations of the available
// request options without disrupting external calls. In the future the
// consumers should be forced to use a more standardized service and
// adhere to a single API derived from this function.
func (c *client) doRequest(
ctx context.Context,
req *Request,
singlePeer *peer.ID,
// In the `GetChainMessages` case, we won't request the headers but we still
// need them to check the integrity of the `CompactedMessages` in the response
// so the tipset blocks need to be provided by the caller.
tipsets []*types.TipSet,
) (*validatedResponse, error) {
// Validate request.
if req.Length == 0 {
return nil, xerrors.Errorf("invalid request of length 0")
}
if req.Length > MaxRequestLength {
return nil, xerrors.Errorf("request length (%d) above maximum (%d)",
req.Length, MaxRequestLength)
}
if req.Options == 0 {
return nil, xerrors.Errorf("request with no options set")
}
// Generate the list of peers to be queried, either the
// `singlePeer` indicated or all peers available (sorted
// by an internal peer tracker with some randomness injected).
var peers []peer.ID
if singlePeer != nil {
peers = []peer.ID{*singlePeer}
} else {
peers = c.getShuffledPeers()
if len(peers) == 0 {
return nil, xerrors.Errorf("no peers available")
}
}
// Try the request for each peer in the list,
// return on the first successful response.
// FIXME: Doing this serially isn't great, but fetching in parallel
// may not be a good idea either. Think about this more.
globalTime := build.Clock.Now()
// Global time used to track what is the expected time we will need to get
// a response if a client fails us.
for _, peer := range peers {
select {
case <-ctx.Done():
return nil, xerrors.Errorf("context cancelled: %w", ctx.Err())
default:
}
// Send request, read response.
res, err := c.sendRequestToPeer(ctx, peer, req)
if err != nil {
if !xerrors.Is(err, network.ErrNoConn) {
log.Warnf("could not send request to peer %s: %s",
peer.String(), err)
}
continue
}
// Process and validate response.
validRes, err := c.processResponse(req, res, tipsets)
if err != nil {
log.Warnf("processing peer %s response failed: %s",
peer.String(), err)
continue
}
c.peerTracker.logGlobalSuccess(build.Clock.Since(globalTime))
c.host.ConnManager().TagPeer(peer, "bsync", SuccessPeerTagValue)
return validRes, nil
}
errString := "doRequest failed for all peers"
if singlePeer != nil {
errString = fmt.Sprintf("doRequest failed for single peer %s", *singlePeer)
}
return nil, xerrors.Errorf(errString)
}
// Process and validate response. Check the status, the integrity of the
// information returned, and that it matches the request. Extract the information
// into a `validatedResponse` for the external-facing APIs to select what they
// need.
//
// We are conflating in the single error returned both status and validation
// errors. Peer penalization should happen here then, before returning, so
// we can apply the correct penalties depending on the cause of the error.
// FIXME: Add the `peer` as argument once we implement penalties.
func (c *client) processResponse(req *Request, res *Response, tipsets []*types.TipSet) (r *validatedResponse, err error) {
err = res.statusToError()
if err != nil {
return nil, xerrors.Errorf("status error: %s", err)
}
defer func() {
if rerr := recover(); rerr != nil {
log.Errorf("process response error: %s", rerr)
err = xerrors.Errorf("process response error: %s", rerr)
return
}
}()
options := parseOptions(req.Options)
if options.noOptionsSet() {
// Safety check: this shouldn't have been sent, and even if it did
// it should have been caught by the peer in its error status.
return nil, xerrors.Errorf("nothing was requested")
}
// Verify that the chain segment returned is in the valid range.
// Note that the returned length might be less than requested.
resLength := len(res.Chain)
if resLength == 0 {
return nil, xerrors.Errorf("got no chain in successful response")
}
if resLength > int(req.Length) {
return nil, xerrors.Errorf("got longer response (%d) than requested (%d)",
resLength, req.Length)
}
if resLength < int(req.Length) && res.Status != Partial {
return nil, xerrors.Errorf("got less than requested without a proper status: %d", res.Status)
}
validRes := &validatedResponse{}
if options.IncludeHeaders {
// Check for valid block sets and extract them into `TipSet`s.
validRes.tipsets = make([]*types.TipSet, resLength)
for i := 0; i < resLength; i++ {
if res.Chain[i] == nil {
return nil, xerrors.Errorf("response with nil tipset in pos %d", i)
}
for blockIdx, block := range res.Chain[i].Blocks {
if block == nil {
return nil, xerrors.Errorf("tipset with nil block in pos %d", blockIdx)
// FIXME: Maybe we should move this check to `NewTipSet`.
}
}
validRes.tipsets[i], err = types.NewTipSet(res.Chain[i].Blocks)
if err != nil {
return nil, xerrors.Errorf("invalid tipset blocks at height (head - %d): %w", i, err)
}
}
// Check that the returned head matches the one requested.
if !types.CidArrsEqual(validRes.tipsets[0].Cids(), req.Head) {
return nil, xerrors.Errorf("returned chain head does not match request")
}
// Check `TipSet`s are connected (valid chain).
for i := 0; i < len(validRes.tipsets)-1; i++ {
if validRes.tipsets[i].IsChildOf(validRes.tipsets[i+1]) == false {
return nil, fmt.Errorf("tipsets are not connected at height (head - %d)/(head - %d)",
i, i+1)
// FIXME: Maybe give more information here, like CIDs.
}
}
}
if options.IncludeMessages {
validRes.messages = make([]*CompactedMessages, resLength)
for i := 0; i < resLength; i++ {
if res.Chain[i].Messages == nil {
return nil, xerrors.Errorf("no messages included for tipset at height (head - %d)", i)
}
validRes.messages[i] = res.Chain[i].Messages
}
if options.IncludeHeaders {
// If the headers were also returned check that the compression
// indexes are valid before `toFullTipSets()` is called by the
// consumer.
err := c.validateCompressedIndices(res.Chain)
if err != nil {
return nil, err
}
} else {
// If we didn't request the headers they should have been provided
// by the caller.
if len(tipsets) < len(res.Chain) {
return nil, xerrors.Errorf("not enought tipsets provided for message response validation, needed %d, have %d", len(res.Chain), len(tipsets))
}
chain := make([]*BSTipSet, 0, resLength)
for i, resChain := range res.Chain {
next := &BSTipSet{
Blocks: tipsets[i].Blocks(),
Messages: resChain.Messages,
}
chain = append(chain, next)
}
err := c.validateCompressedIndices(chain)
if err != nil {
return nil, err
}
}
}
return validRes, nil
}
func (c *client) validateCompressedIndices(chain []*BSTipSet) error {
resLength := len(chain)
for tipsetIdx := 0; tipsetIdx < resLength; tipsetIdx++ {
msgs := chain[tipsetIdx].Messages
blocksNum := len(chain[tipsetIdx].Blocks)
if len(msgs.BlsIncludes) != blocksNum {
return xerrors.Errorf("BlsIncludes (%d) does not match number of blocks (%d)",
len(msgs.BlsIncludes), blocksNum)
}
if len(msgs.SecpkIncludes) != blocksNum {
return xerrors.Errorf("SecpkIncludes (%d) does not match number of blocks (%d)",
len(msgs.SecpkIncludes), blocksNum)
}
for blockIdx := 0; blockIdx < blocksNum; blockIdx++ {
for _, mi := range msgs.BlsIncludes[blockIdx] {
if int(mi) >= len(msgs.Bls) {
return xerrors.Errorf("index in BlsIncludes (%d) exceeds number of messages (%d)",
mi, len(msgs.Bls))
}
}
for _, mi := range msgs.SecpkIncludes[blockIdx] {
if int(mi) >= len(msgs.Secpk) {
return xerrors.Errorf("index in SecpkIncludes (%d) exceeds number of messages (%d)",
mi, len(msgs.Secpk))
}
}
}
}
return nil
}
// GetBlocks implements Client.GetBlocks(). Refer to the godocs there.
func (c *client) GetBlocks(ctx context.Context, tsk types.TipSetKey, count int) ([]*types.TipSet, error) {
ctx, span := trace.StartSpan(ctx, "bsync.GetBlocks")
defer span.End()
if span.IsRecordingEvents() {
span.AddAttributes(
trace.StringAttribute("tipset", fmt.Sprint(tsk.Cids())),
trace.Int64Attribute("count", int64(count)),
)
}
req := &Request{
Head: tsk.Cids(),
Length: uint64(count),
Options: Headers,
}
validRes, err := c.doRequest(ctx, req, nil, nil)
if err != nil {
return nil, err
}
return validRes.tipsets, nil
}
// GetFullTipSet implements Client.GetFullTipSet(). Refer to the godocs there.
func (c *client) GetFullTipSet(ctx context.Context, peer peer.ID, tsk types.TipSetKey) (*store.FullTipSet, error) {
// TODO: round robin through these peers on error
req := &Request{
Head: tsk.Cids(),
Length: 1,
Options: Headers | Messages,
}
validRes, err := c.doRequest(ctx, req, &peer, nil)
if err != nil {
return nil, err
}
return validRes.toFullTipSets()[0], nil
// If `doRequest` didn't fail we are guaranteed to have at least
// *one* tipset here, so it's safe to index directly.
}
// GetChainMessages implements Client.GetChainMessages(). Refer to the godocs there.
func (c *client) GetChainMessages(ctx context.Context, tipsets []*types.TipSet) ([]*CompactedMessages, error) {
head := tipsets[0]
length := uint64(len(tipsets))
ctx, span := trace.StartSpan(ctx, "GetChainMessages")
if span.IsRecordingEvents() {
span.AddAttributes(
trace.StringAttribute("tipset", fmt.Sprint(head.Cids())),
trace.Int64Attribute("count", int64(length)),
)
}
defer span.End()
req := &Request{
Head: head.Cids(),
Length: length,
Options: Messages,
}
validRes, err := c.doRequest(ctx, req, nil, tipsets)
if err != nil {
return nil, err
}
return validRes.messages, nil
}
// Send a request to a peer. Write request in the stream and read the
// response back. We do not do any processing of the request/response
// here.
func (c *client) sendRequestToPeer(ctx context.Context, peer peer.ID, req *Request) (_ *Response, err error) {
// Trace code.
ctx, span := trace.StartSpan(ctx, "sendRequestToPeer")
defer span.End()
if span.IsRecordingEvents() {
span.AddAttributes(
trace.StringAttribute("peer", peer.Pretty()),
)
}
defer func() {
if err != nil {
if span.IsRecordingEvents() {
span.SetStatus(trace.Status{
Code: 5,
Message: err.Error(),
})
}
}
}()
// -- TRACE --
supported, err := c.host.Peerstore().SupportsProtocols(peer, ChainExchangeProtocolID)
if err != nil {
c.RemovePeer(peer)
return nil, xerrors.Errorf("failed to get protocols for peer: %w", err)
}
if len(supported) == 0 || (supported[0] != ChainExchangeProtocolID) {
return nil, xerrors.Errorf("peer %s does not support protocols %s",
peer, []string{ChainExchangeProtocolID})
}
connectionStart := build.Clock.Now()
// Open stream to peer.
stream, err := c.host.NewStream(
network.WithNoDial(ctx, "should already have connection"),
peer,
ChainExchangeProtocolID)
if err != nil {
c.RemovePeer(peer)
return nil, xerrors.Errorf("failed to open stream to peer: %w", err)
}
defer stream.Close() //nolint:errcheck
// Write request.
_ = stream.SetWriteDeadline(time.Now().Add(WriteReqDeadline))
if err := cborutil.WriteCborRPC(stream, req); err != nil {
_ = stream.SetWriteDeadline(time.Time{})
c.peerTracker.logFailure(peer, build.Clock.Since(connectionStart), req.Length)
// FIXME: Should we also remove peer here?
return nil, err
}
_ = stream.SetWriteDeadline(time.Time{}) // clear deadline // FIXME: Needs
// its own API (https://github.com/libp2p/go-libp2p-core/issues/162).
// Read response.
var res Response
err = cborutil.ReadCborRPC(
bufio.NewReader(incrt.New(stream, ReadResMinSpeed, ReadResDeadline)),
&res)
if err != nil {
c.peerTracker.logFailure(peer, build.Clock.Since(connectionStart), req.Length)
return nil, xerrors.Errorf("failed to read chainxchg response: %w", err)
}
// FIXME: Move all this together at the top using a defer as done elsewhere.
// Maybe we need to declare `res` in the signature.
if span.IsRecordingEvents() {
span.AddAttributes(
trace.Int64Attribute("resp_status", int64(res.Status)),
trace.StringAttribute("msg", res.ErrorMessage),
trace.Int64Attribute("chain_len", int64(len(res.Chain))),
)
}
c.peerTracker.logSuccess(peer, build.Clock.Since(connectionStart), uint64(len(res.Chain)))
// FIXME: We should really log a success only after we validate the response.
// It might be a bit hard to do.
return &res, nil
}
// AddPeer implements Client.AddPeer(). Refer to the godocs there.
func (c *client) AddPeer(p peer.ID) {
c.peerTracker.addPeer(p)
}
// RemovePeer implements Client.RemovePeer(). Refer to the godocs there.
func (c *client) RemovePeer(p peer.ID) {
c.peerTracker.removePeer(p)
}
// getShuffledPeers returns a preference-sorted set of peers (by latency
// and failure counting), shuffling the first few peers so we don't always
// pick the same peer.
// FIXME: Consider merging with `shufflePrefix()s`.
func (c *client) getShuffledPeers() []peer.ID {
peers := c.peerTracker.prefSortedPeers()
shufflePrefix(peers)
return peers
}
func shufflePrefix(peers []peer.ID) {
prefix := ShufflePeersPrefix
if len(peers) < prefix {
prefix = len(peers)
}
buf := make([]peer.ID, prefix)
perm := rand.Perm(prefix)
for i, v := range perm {
buf[i] = peers[v]
}
copy(peers, buf)
}