package consul import ( "crypto/tls" "fmt" "io" "math/rand" "net" "strings" "time" "github.com/armon/go-metrics" "github.com/hashicorp/consul/consul/structs" "github.com/hashicorp/go-msgpack/codec" "github.com/hashicorp/yamux" "github.com/inconshreveable/muxado" ) type RPCType byte const ( rpcConsul RPCType = iota rpcRaft rpcMultiplex rpcTLS rpcMultiplexV2 ) const ( // maxQueryTime is used to bound the limit of a blocking query maxQueryTime = 600 * time.Second // Warn if the Raft command is larger than this. // If it's over 1MB something is probably being abusive. raftWarnSize = 1024 * 1024 // enqueueLimit caps how long we will wait to enqueue // a new Raft command. Something is probably wrong if this // value is ever reached. However, it prevents us from blocking // the requesting goroutine forever. enqueueLimit = 30 * time.Second ) // listen is used to listen for incoming RPC connections func (s *Server) listen() { for { // Accept a connection conn, err := s.rpcListener.Accept() if err != nil { if s.shutdown { return } s.logger.Printf("[ERR] consul.rpc: failed to accept RPC conn: %v", err) continue } go s.handleConn(conn, false) metrics.IncrCounter([]string{"consul", "rpc", "accept_conn"}, 1) } } // handleConn is used to determine if this is a Raft or // Consul type RPC connection and invoke the correct handler func (s *Server) handleConn(conn net.Conn, isTLS bool) { // Read a single byte buf := make([]byte, 1) if _, err := conn.Read(buf); err != nil { if err != io.EOF { s.logger.Printf("[ERR] consul.rpc: failed to read byte: %v", err) } conn.Close() return } // Enforce TLS if VerifyIncoming is set if s.config.VerifyIncoming && !isTLS && RPCType(buf[0]) != rpcTLS { s.logger.Printf("[WARN] consul.rpc: Non-TLS connection attempted with VerifyIncoming set") conn.Close() return } // Switch on the byte switch RPCType(buf[0]) { case rpcConsul: s.handleConsulConn(conn) case rpcRaft: metrics.IncrCounter([]string{"consul", "rpc", "raft_handoff"}, 1) s.raftLayer.Handoff(conn) case rpcMultiplex: s.handleMultiplex(conn) case rpcTLS: if s.rpcTLS == nil { s.logger.Printf("[WARN] consul.rpc: TLS connection attempted, server not configured for TLS") conn.Close() return } conn = tls.Server(conn, s.rpcTLS) s.handleConn(conn, true) case rpcMultiplexV2: s.handleMultiplexV2(conn) default: s.logger.Printf("[ERR] consul.rpc: unrecognized RPC byte: %v", buf[0]) conn.Close() return } } // handleMultiplex is used to multiplex a single incoming connection // using the Muxado multiplexer func (s *Server) handleMultiplex(conn net.Conn) { defer conn.Close() server := muxado.Server(conn) for { sub, err := server.Accept() if err != nil { if !strings.Contains(err.Error(), "closed") { s.logger.Printf("[ERR] consul.rpc: multiplex conn accept failed: %v", err) } return } go s.handleConsulConn(sub) } } // handleMultiplexV2 is used to multiplex a single incoming connection // using the Yamux multiplexer func (s *Server) handleMultiplexV2(conn net.Conn) { defer conn.Close() conf := yamux.DefaultConfig() conf.LogOutput = s.config.LogOutput server, _ := yamux.Server(conn, conf) for { sub, err := server.Accept() if err != nil { if err != io.EOF { s.logger.Printf("[ERR] consul.rpc: multiplex conn accept failed: %v", err) } return } go s.handleConsulConn(sub) } } // handleConsulConn is used to service a single Consul RPC connection func (s *Server) handleConsulConn(conn net.Conn) { defer conn.Close() rpcCodec := codec.GoRpc.ServerCodec(conn, msgpackHandle) for { select { case <-s.shutdownCh: return default: } if err := s.rpcServer.ServeRequest(rpcCodec); err != nil { if err != io.EOF && !strings.Contains(err.Error(), "closed") { s.logger.Printf("[ERR] consul.rpc: RPC error: %v (%v)", err, conn) } return } } } // forward is used to forward to a remote DC or to forward to the local leader // Returns a bool of if forwarding was performed, as well as any error func (s *Server) forward(method string, info structs.RPCInfo, args interface{}, reply interface{}) (bool, error) { // Handle DC forwarding dc := info.RequestDatacenter() if dc != s.config.Datacenter { err := s.forwardDC(method, dc, args, reply) return true, err } // Check if we can allow a stale read if info.IsRead() && info.AllowStaleRead() { return false, nil } // Handle leader forwarding if !s.IsLeader() { err := s.forwardLeader(method, args, reply) return true, err } return false, nil } // forwardLeader is used to forward an RPC call to the leader, or fail if no leader func (s *Server) forwardLeader(method string, args interface{}, reply interface{}) error { // Get the leader leader := s.raft.Leader() if leader == nil { return structs.ErrNoLeader } // Lookup the server s.localLock.RLock() server := s.localConsuls[leader.String()] s.localLock.RUnlock() // Handle a missing server if server == nil { return structs.ErrNoLeader } return s.connPool.RPC(server.Addr, server.Version, method, args, reply) } // forwardDC is used to forward an RPC call to a remote DC, or fail if no servers func (s *Server) forwardDC(method, dc string, args interface{}, reply interface{}) error { // Bail if we can't find any servers s.remoteLock.RLock() servers := s.remoteConsuls[dc] if len(servers) == 0 { s.remoteLock.RUnlock() s.logger.Printf("[WARN] consul.rpc: RPC request for DC '%s', no path found", dc) return structs.ErrNoDCPath } // Select a random addr offset := rand.Int31() % int32(len(servers)) server := servers[offset] s.remoteLock.RUnlock() // Forward to remote Consul metrics.IncrCounter([]string{"consul", "rpc", "cross-dc", dc}, 1) return s.connPool.RPC(server.Addr, server.Version, method, args, reply) } // globalRPC is used to forward an RPC request to one server in each datacenter. // This will only error for RPC-related errors. Otherwise, application-level // errors can be sent in the response objects. func (s *Server) globalRPC(method string, args interface{}, reply structs.CompoundResponse) error { errorCh := make(chan error) respCh := make(chan interface{}) // Make a new request into each datacenter for dc, _ := range s.remoteConsuls { go func(dc string) { rr := reply.New() if err := s.forwardDC(method, dc, args, &rr); err != nil { errorCh <- err return } respCh <- rr }(dc) } replies, total := 0, len(s.remoteConsuls) for replies < total { select { case err := <-errorCh: return err case rr := <-respCh: reply.Add(rr) replies++ } } return nil } // raftApply is used to encode a message, run it through raft, and return // the FSM response along with any errors func (s *Server) raftApply(t structs.MessageType, msg interface{}) (interface{}, error) { buf, err := structs.Encode(t, msg) if err != nil { return nil, fmt.Errorf("Failed to encode request: %v", err) } // Warn if the command is very large if n := len(buf); n > raftWarnSize { s.logger.Printf("[WARN] consul: Attempting to apply large raft entry (%d bytes)", n) } future := s.raft.Apply(buf, enqueueLimit) if err := future.Error(); err != nil { return nil, err } return future.Response(), nil } // blockingRPC is used for queries that need to wait for a // minimum index. This is used to block and wait for changes. func (s *Server) blockingRPC(b *structs.QueryOptions, m *structs.QueryMeta, tables MDBTables, run func() error) error { var timeout <-chan time.Time var notifyCh chan struct{} // Fast path non-blocking if b.MinQueryIndex == 0 { goto RUN_QUERY } // Sanity check that we have tables to block on if len(tables) == 0 { panic("no tables to block on") } // Restrict the max query time if b.MaxQueryTime > maxQueryTime { b.MaxQueryTime = maxQueryTime } // Ensure a time limit is set if we have an index if b.MinQueryIndex > 0 && b.MaxQueryTime == 0 { b.MaxQueryTime = maxQueryTime } // Setup a query timeout if b.MaxQueryTime > 0 { timeout = time.After(b.MaxQueryTime) } // Setup a notification channel for changes SETUP_NOTIFY: if b.MinQueryIndex > 0 { notifyCh = make(chan struct{}, 1) s.fsm.State().Watch(tables, notifyCh) } RUN_QUERY: // Update the query meta data s.setQueryMeta(m) // Check if query must be consistent if b.RequireConsistent { if err := s.consistentRead(); err != nil { return err } } // Run the query function err := run() // Check for minimum query time if err == nil && m.Index > 0 && m.Index <= b.MinQueryIndex { select { case <-notifyCh: goto SETUP_NOTIFY case <-timeout: } } return err } // setQueryMeta is used to populate the QueryMeta data for an RPC call func (s *Server) setQueryMeta(m *structs.QueryMeta) { if s.IsLeader() { m.LastContact = 0 m.KnownLeader = true } else { m.LastContact = time.Now().Sub(s.raft.LastContact()) m.KnownLeader = (s.raft.Leader() != nil) } } // consistentRead is used to ensure we do not perform a stale // read. This is done by verifying leadership before the read. func (s *Server) consistentRead() error { defer metrics.MeasureSince([]string{"consul", "rpc", "consistentRead"}, time.Now()) future := s.raft.VerifyLeader() return future.Error() }