package agent import ( "encoding/base64" "fmt" "net/http" "strings" "time" "github.com/hashicorp/consul/agent/structs" "github.com/hashicorp/consul/api" "github.com/hashicorp/consul/types" ) const ( // maxTxnOps is used to set an upper limit on the number of operations // inside a transaction. If there are more operations than this, then the // client is likely abusing transactions. maxTxnOps = 64 ) // decodeValue decodes the value member of the given operation. func decodeValue(rawKV interface{}) error { rawMap, ok := rawKV.(map[string]interface{}) if !ok { return fmt.Errorf("unexpected raw KV type: %T", rawKV) } for k, v := range rawMap { switch strings.ToLower(k) { case "value": // Leave the byte slice nil if we have a nil // value. if v == nil { return nil } // Otherwise, base64 decode it. s, ok := v.(string) if !ok { return fmt.Errorf("unexpected value type: %T", v) } decoded, err := base64.StdEncoding.DecodeString(s) if err != nil { return fmt.Errorf("failed to decode value: %v", err) } rawMap[k] = decoded return nil } } return nil } // isWrite returns true if the given operation alters the state store. func isWrite(op api.KVOp) bool { switch op { case api.KVSet, api.KVDelete, api.KVDeleteCAS, api.KVDeleteTree, api.KVCAS, api.KVLock, api.KVUnlock: return true } return false } // convertOps takes the incoming body in API format and converts it to the // internal RPC format. This returns a count of the number of write ops, and // a boolean, that if false means an error response has been generated and // processing should stop. func (s *HTTPHandlers) convertOps(resp http.ResponseWriter, req *http.Request) (structs.TxnOps, int, bool) { // The TxnMaxReqLen limit and KVMaxValueSize limit both default to the // suggested raft data size and can be configured independently. The // TxnMaxReqLen is enforced on the cumulative size of the transaction, // whereas the KVMaxValueSize limit is imposed on the values of individual KV // operations -- this is to keep consistent with the behavior for KV values // in the kvs endpoint. // // The defaults are set to the suggested raft size to keep the total // transaction size reasonable to account for timely heartbeat signals. If // the TxnMaxReqLen limit is above the raft's suggested threshold, large // transactions are automatically set to attempt a chunking apply. // Performance may degrade and warning messages may appear. maxTxnLen := int64(s.agent.config.TxnMaxReqLen) kvMaxValueSize := int64(s.agent.config.KVMaxValueSize) // For backward compatibility, KVMaxValueSize is used as the max txn request // length if it is configured greater than TxnMaxReqLen or its default if maxTxnLen < kvMaxValueSize { maxTxnLen = kvMaxValueSize } // Check Content-Length first before decoding to return early if req.ContentLength > maxTxnLen { resp.WriteHeader(http.StatusRequestEntityTooLarge) fmt.Fprintf(resp, "Request body(%d bytes) too large, max size: %d bytes. See %s.", req.ContentLength, maxTxnLen, "https://www.consul.io/docs/agent/options.html#txn_max_req_len", ) return nil, 0, false } var ops api.TxnOps req.Body = http.MaxBytesReader(resp, req.Body, maxTxnLen) if err := decodeBody(req.Body, &ops); err != nil { if err.Error() == "http: request body too large" { // The request size is also verified during decoding to double check // if the Content-Length header was not set by the client. resp.WriteHeader(http.StatusRequestEntityTooLarge) fmt.Fprintf(resp, "Request body too large, max size: %d bytes. See %s.", maxTxnLen, "https://www.consul.io/docs/agent/options.html#txn_max_req_len", ) } else { // Note the body is in API format, and not the RPC format. If we can't // decode it, we will return a 400 since we don't have enough context to // associate the error with a given operation. resp.WriteHeader(http.StatusBadRequest) fmt.Fprintf(resp, "Failed to parse body: %v", err) } return nil, 0, false } // Enforce a reasonable upper limit on the number of operations in a // transaction in order to curb abuse. if size := len(ops); size > maxTxnOps { resp.WriteHeader(http.StatusRequestEntityTooLarge) fmt.Fprintf(resp, "Transaction contains too many operations (%d > %d)", size, maxTxnOps) return nil, 0, false } // Convert the KV API format into the RPC format. Note that fixupKVOps // above will have already converted the base64 encoded strings into // byte arrays so we can assign right over. var opsRPC structs.TxnOps var writes int for _, in := range ops { switch { case in.KV != nil: size := len(in.KV.Value) if int64(size) > kvMaxValueSize { resp.WriteHeader(http.StatusRequestEntityTooLarge) fmt.Fprintf(resp, "Value for key %q is too large (%d > %d bytes)", in.KV.Key, size, s.agent.config.KVMaxValueSize) return nil, 0, false } verb := in.KV.Verb if isWrite(verb) { writes++ } out := &structs.TxnOp{ KV: &structs.TxnKVOp{ Verb: verb, DirEnt: structs.DirEntry{ Key: in.KV.Key, Value: in.KV.Value, Flags: in.KV.Flags, Session: in.KV.Session, EnterpriseMeta: structs.NewEnterpriseMeta(in.KV.Namespace), RaftIndex: structs.RaftIndex{ ModifyIndex: in.KV.Index, }, }, }, } opsRPC = append(opsRPC, out) case in.Node != nil: if in.Node.Verb != api.NodeGet { writes++ } // Setup the default DC if not provided if in.Node.Node.Datacenter == "" { in.Node.Node.Datacenter = s.agent.config.Datacenter } node := in.Node.Node out := &structs.TxnOp{ Node: &structs.TxnNodeOp{ Verb: in.Node.Verb, Node: structs.Node{ ID: types.NodeID(node.ID), Node: node.Node, Address: node.Address, Datacenter: node.Datacenter, TaggedAddresses: node.TaggedAddresses, Meta: node.Meta, RaftIndex: structs.RaftIndex{ ModifyIndex: node.ModifyIndex, }, }, }, } opsRPC = append(opsRPC, out) case in.Service != nil: if in.Service.Verb != api.ServiceGet { writes++ } svc := in.Service.Service out := &structs.TxnOp{ Service: &structs.TxnServiceOp{ Verb: in.Service.Verb, Node: in.Service.Node, Service: structs.NodeService{ ID: svc.ID, Service: svc.Service, Tags: svc.Tags, Address: svc.Address, Meta: svc.Meta, Port: svc.Port, Weights: &structs.Weights{ Passing: svc.Weights.Passing, Warning: svc.Weights.Warning, }, EnableTagOverride: svc.EnableTagOverride, EnterpriseMeta: structs.NewEnterpriseMeta(svc.Namespace), RaftIndex: structs.RaftIndex{ ModifyIndex: svc.ModifyIndex, }, }, }, } opsRPC = append(opsRPC, out) case in.Check != nil: if in.Check.Verb != api.CheckGet { writes++ } check := in.Check.Check // Check if the internal duration fields are set as well as the normal ones. This is // to be backwards compatible with a bug where the internal duration fields were being // deserialized from instead of the correct fields. // See https://github.com/hashicorp/consul/issues/5477 for more details. interval := check.Definition.IntervalDuration if dur := time.Duration(check.Definition.Interval); dur != 0 { interval = dur } timeout := check.Definition.TimeoutDuration if dur := time.Duration(check.Definition.Timeout); dur != 0 { timeout = dur } deregisterCriticalServiceAfter := check.Definition.DeregisterCriticalServiceAfterDuration if dur := time.Duration(check.Definition.DeregisterCriticalServiceAfter); dur != 0 { deregisterCriticalServiceAfter = dur } out := &structs.TxnOp{ Check: &structs.TxnCheckOp{ Verb: in.Check.Verb, Check: structs.HealthCheck{ Node: check.Node, CheckID: types.CheckID(check.CheckID), Name: check.Name, Status: check.Status, Notes: check.Notes, Output: check.Output, ServiceID: check.ServiceID, ServiceName: check.ServiceName, ServiceTags: check.ServiceTags, Definition: structs.HealthCheckDefinition{ HTTP: check.Definition.HTTP, TLSServerName: check.Definition.TLSServerName, TLSSkipVerify: check.Definition.TLSSkipVerify, Header: check.Definition.Header, Method: check.Definition.Method, Body: check.Definition.Body, TCP: check.Definition.TCP, Interval: interval, Timeout: timeout, DeregisterCriticalServiceAfter: deregisterCriticalServiceAfter, }, EnterpriseMeta: structs.NewEnterpriseMeta(check.Namespace), RaftIndex: structs.RaftIndex{ ModifyIndex: check.ModifyIndex, }, }, }, } opsRPC = append(opsRPC, out) } } return opsRPC, writes, true } // Txn handles requests to apply multiple operations in a single, atomic // transaction. A transaction consisting of only read operations will be fast- // pathed to an endpoint that supports consistency modes (but not blocking), // and everything else will be routed through Raft like a normal write. func (s *HTTPHandlers) Txn(resp http.ResponseWriter, req *http.Request) (interface{}, error) { // Convert the ops from the API format to the internal format. ops, writes, ok := s.convertOps(resp, req) if !ok { return nil, nil } // Fast-path a transaction with only writes to the read-only endpoint, // which bypasses Raft, and allows for staleness. conflict := false var ret interface{} if writes == 0 { args := structs.TxnReadRequest{Ops: ops} if done := s.parse(resp, req, &args.Datacenter, &args.QueryOptions); done { return nil, nil } var reply structs.TxnReadResponse if err := s.agent.RPC("Txn.Read", &args, &reply); err != nil { return nil, err } // Since we don't do blocking, we only add the relevant headers // for metadata. setLastContact(resp, reply.LastContact) setKnownLeader(resp, reply.KnownLeader) ret, conflict = reply, len(reply.Errors) > 0 } else { args := structs.TxnRequest{Ops: ops} s.parseDC(req, &args.Datacenter) s.parseToken(req, &args.Token) var reply structs.TxnResponse if err := s.agent.RPC("Txn.Apply", &args, &reply); err != nil { return nil, err } ret, conflict = reply, len(reply.Errors) > 0 } // If there was a conflict return the response object but set a special // status code. if conflict { var buf []byte var err error buf, err = s.marshalJSON(req, ret) if err != nil { return nil, err } resp.Header().Set("Content-Type", "application/json") resp.WriteHeader(http.StatusConflict) resp.Write(buf) return nil, nil } // Otherwise, return the results of the successful transaction. return ret, nil }