Refactored registration to align with the spec

* We now keep track of sessions and their completed registration stages.
* We only complete registration if the client has completed a full flow.
* New Derived section in config for data derived from config options.
* New config options for captcha.
* Send params back to client for each registration stage.

Signed-off-by: Andrew (anoa) <anoa@openmailbox.org>

src/github.com/matrix-org/dendrite/clientapi/auth/authtypes/flow.go

@@ -0,0 +1,21 @@
+// Copyright 2017 Vector Creations Ltd
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package authtypes
+
+// Flow represents one possible way that the client can authenticate a request.
+// http://matrix.org/docs/spec/HEAD/client_server/r0.3.0.html#user-interactive-authentication-api
+type Flow struct {
+	Stages []LoginType `json:"stages"`
+}

src/github.com/matrix-org/dendrite/clientapi/routing/register.go

@@ -23,8 +23,8 @@ import (
 	"fmt"
 	"net/http"
 	"regexp"
+	"sort"
 	"strings"
-	"time"
 
 	"github.com/matrix-org/dendrite/common/config"
 
@@ -43,9 +43,14 @@ const (
 	minPasswordLength = 8   // http://matrix.org/docs/spec/client_server/r0.2.0.html#password-based
 	maxPasswordLength = 512 // https://github.com/matrix-org/synapse/blob/v0.20.0/synapse/rest/client/v2_alpha/register.py#L161
 	maxUsernameLength = 254 // http://matrix.org/speculator/spec/HEAD/intro.html#user-identifiers TODO account for domain
+	sessionIDLength   = 24
 )
 
-var validUsernameRegex = regexp.MustCompile(`^[0-9a-zA-Z_\-./]+$`)
+var (
+	// TODO: Remove old sessions. Need to do so on a session-specific timeout.
+	sessions           = make(map[string][]authtypes.LoginType) // Sessions and completed flow stages
+	validUsernameRegex = regexp.MustCompile(`^[0-9a-zA-Z_\-./]+$`)
+)
 
 // registerRequest represents the submitted registration request.
 // It can be broken down into 2 sections: the auth dictionary and registration parameters.
@@ -68,23 +73,18 @@ type authDict struct {
 	Type    authtypes.LoginType         `json:"type"`
 	Session string                      `json:"session"`
 	Mac     gomatrixserverlib.HexString `json:"mac"`
+
 	// TODO: Lots of custom keys depending on the type
 }
 
 // http://matrix.org/speculator/spec/HEAD/client_server/unstable.html#user-interactive-authentication-api
 type userInteractiveResponse struct {
-	Flows     []authFlow             `json:"flows"`
+	Flows     []authtypes.Flow       `json:"flows"`
 	Completed []authtypes.LoginType  `json:"completed"`
 	Params    map[string]interface{} `json:"params"`
 	Session   string                 `json:"session"`
 }
 
-// authFlow represents one possible way that the client can authenticate a request.
-// http://matrix.org/speculator/spec/HEAD/client_server/unstable.html#user-interactive-authentication-api
-type authFlow struct {
-	Stages []authtypes.LoginType `json:"stages"`
-}
-
 // legacyRegisterRequest represents the submitted registration request for v1 API.
 type legacyRegisterRequest struct {
 	Password string                      `json:"password"`
@@ -94,9 +94,15 @@ type legacyRegisterRequest struct {
 	Mac      gomatrixserverlib.HexString `json:"mac"`
 }
 
-func newUserInteractiveResponse(sessionID string, fs []authFlow) userInteractiveResponse {
+// newUserInteractiveResponse will return a struct to be sent back to the client
+// during registration.
+func newUserInteractiveResponse(
+	sessionID string,
+	fs []authtypes.Flow,
+	params map[string]interface{},
+) userInteractiveResponse {
 	return userInteractiveResponse{
-		fs, []authtypes.LoginType{}, make(map[string]interface{}), sessionID,
+		fs, sessions[sessionID], params, sessionID,
 	}
 }
 
@@ -154,22 +160,26 @@ func Register(
 	deviceDB *devices.Database,
 	cfg *config.Dendrite,
 ) util.JSONResponse {
+
 	var r registerRequest
 	resErr := httputil.UnmarshalJSONRequest(req, &r)
 	if resErr != nil {
 		return *resErr
 	}
 
-	// All registration requests must specify what auth they are using to perform this request
+	// Retrieve or generate the sessionID
+	sessionID := r.Auth.Session
+	if sessionID == "" {
+		// Generate a new, random session ID
+		sessionID = util.RandomString(sessionIDLength)
+	}
+
+	// If no auth type is specified by the client, send back the list of available flows
 	if r.Auth.Type == "" {
 		return util.JSONResponse{
 			Code: 401,
-			// TODO: Hard-coded 'dummy' auth for now with a bogus session ID.
-			//       Server admins should be able to change things around (eg enable captcha)
-			JSON: newUserInteractiveResponse(time.Now().String(), []authFlow{
-				{[]authtypes.LoginType{authtypes.LoginTypeDummy}},
-				{[]authtypes.LoginType{authtypes.LoginTypeSharedSecret}},
-			}),
+			JSON: newUserInteractiveResponse(sessionID,
+				cfg.Derived.Registration.Flows, cfg.Derived.Registration.Params),
 		}
 	}
 
@@ -187,6 +197,19 @@ func Register(
 		"session_id": r.Auth.Session,
 	}).Info("Processing registration request")
 
+	return handleRegistrationFlow(req, r, sessionID, cfg, accountDB, deviceDB)
+}
+
+// handleRegistrationFlow will direct and complete registration flow stages
+// that the client has requested.
+func handleRegistrationFlow(
+	req *http.Request,
+	r registerRequest,
+	sessionID string,
+	cfg *config.Dendrite,
+	accountDB *accounts.Database,
+	deviceDB *devices.Database,
+) util.JSONResponse {
 	// TODO: Shared secret registration (create new user scripts)
 	// TODO: AS API registration
 	// TODO: Enable registration config flag
@@ -202,7 +225,8 @@ func Register(
 			return util.MessageResponse(400, "Shared secret registration is disabled")
 		}
 
-		valid, err := isValidMacLogin(r.Username, r.Password, r.Admin, r.Auth.Mac, cfg.Matrix.RegistrationSharedSecret)
+		valid, err := isValidMacLogin(r.Username, r.Password, r.Admin,
+			r.Auth.Mac, cfg.Matrix.RegistrationSharedSecret)
 
 		if err != nil {
 			return httputil.LogThenError(req, err)
@@ -212,16 +236,36 @@ func Register(
 			return util.MessageResponse(403, "HMAC incorrect")
 		}
 
-		return completeRegistration(req.Context(), accountDB, deviceDB, r.Username, r.Password, r.InitialDisplayName)
+		// Add SharedSecret to the list of completed registration stages
+		sessions[sessionID] = append(sessions[sessionID], authtypes.LoginTypeSharedSecret)
+
 	case authtypes.LoginTypeDummy:
 		// there is nothing to do
-		return completeRegistration(req.Context(), accountDB, deviceDB, r.Username, r.Password, r.InitialDisplayName)
+		// Add Dummy to the list of completed registration stages
+		sessions[sessionID] = append(sessions[sessionID], authtypes.LoginTypeDummy)
+
 	default:
 		return util.JSONResponse{
 			Code: 501,
 			JSON: jsonerror.Unknown("unknown/unimplemented auth type"),
 		}
 	}
+
+	// Check if a registration flow has been completed successfully
+	for _, flow := range cfg.Derived.Registration.Flows {
+		if checkFlowsEqual(flow, authtypes.Flow{sessions[sessionID]}) {
+			return completeRegistration(req.Context(), accountDB, deviceDB,
+				r.Username, r.Password, r.InitialDisplayName)
+		}
+	}
+
+	// There are still more stages to complete.
+	// Return the flows and those that have been completed.
+	return util.JSONResponse{
+		Code: 401,
+		JSON: newUserInteractiveResponse(sessionID,
+			cfg.Derived.Registration.Flows, cfg.Derived.Registration.Params),
+	}
 }
 
 // LegacyRegister process register requests from the legacy v1 API
@@ -348,7 +392,7 @@ func isValidMacLogin(
 	givenMac []byte,
 	sharedSecret string,
 ) (bool, error) {
-	// Double check that username/passowrd don't contain the HMAC delimiters. We should have
+	// Double check that username/password don't contain the HMAC delimiters. We should have
 	// already checked this.
 	if strings.Contains(username, "\x00") {
 		return false, errors.New("Username contains invalid character")
@@ -376,6 +420,31 @@ func isValidMacLogin(
 	return hmac.Equal(givenMac, expectedMAC), nil
 }
 
+// checkFlowsEqual checks if two registration flows have the same stages
+// within them. Order of stages does not matter.
+func checkFlowsEqual(aFlow, bFlow authtypes.Flow) bool {
+	a := aFlow.Stages
+	b := bFlow.Stages
+	if len(a) != len(b) {
+		return false
+	}
+	sort.Slice(a, func(i, j int) bool { return a[i] < a[j] })
+	sort.Slice(b, func(i, j int) bool { return b[i] < b[j] })
+
+	// Account for any extra stages a user may do unnecessarily
+	extraStages := len(b) - len(a)
+	for i := range b {
+		if extraStages < 0 {
+			return false
+		}
+		if a[i] != b[i] {
+			extraStages--
+			continue
+		}
+	}
+	return true
+}
+
 type availableResponse struct {
 	Available bool `json:"available"`
 }

src/github.com/matrix-org/dendrite/common/config/config.go

@@ -25,6 +25,7 @@ import (
 	"strings"
 	"time"
 
+	"github.com/matrix-org/dendrite/clientapi/auth/authtypes"
 	"github.com/matrix-org/gomatrixserverlib"
 	"github.com/sirupsen/logrus"
 	"golang.org/x/crypto/ed25519"
@@ -189,6 +190,21 @@ type Dendrite struct {
 		// The config for the jaeger opentracing reporter.
 		Jaeger jaegerconfig.Configuration `yaml:"jaeger"`
 	}
+
+	// Any information derived from the configuration options for later use.
+	Derived struct {
+		Registration struct {
+			// Flows is a slice of flows, which represent one possible way that the client can authenticate a request.
+			// http://matrix.org/docs/spec/HEAD/client_server/r0.3.0.html#user-interactive-authentication-api
+			// As long as the generated flows only rely on config file options,
+			// we can generate them on startup and store them until needed
+			Flows []authtypes.Flow `json:"flows"`
+
+			// Params that need to be returned to the client during
+			// registration in order to complete registration stages.
+			Params map[string]interface{} `json:"params"`
+		}
+	}
 }
 
 // A Path on the filesystem.
@@ -305,9 +321,28 @@ func loadConfig(
 
 	config.Media.AbsBasePath = Path(absPath(basePath, config.Media.BasePath))
 
+	// Generate data from config options
+	config.derive()
+
 	return &config, nil
 }
 
+// derive generates data that is derived from various values provided in
+// the config file.
+func (config *Dendrite) derive() {
+	// Determine registrations flows based off config values
+
+	config.Derived.Registration.Params = make(map[string]interface{})
+
+	// TODO: Add email auth type
+	// TODO: Add MSISDN auth type
+	// TODO: Add Recaptcha auth type
+
+	config.Derived.Registration.Flows = append(config.Derived.Registration.Flows,
+		authtypes.Flow{[]authtypes.LoginType{authtypes.LoginTypeDummy}})
+}
+
+// setDefaults sets default config values if they are not explicitly set.
 func (config *Dendrite) setDefaults() {
 	if config.Matrix.KeyValidityPeriod == 0 {
 		config.Matrix.KeyValidityPeriod = 24 * time.Hour
@@ -327,6 +362,8 @@ func (config *Dendrite) setDefaults() {
 	}
 }
 
+// Error returns a string detailing how many errors were contained within an
+// Error type.
 func (e Error) Error() string {
 	if len(e.Problems) == 1 {
 		return e.Problems[0]
@@ -336,6 +373,8 @@ func (e Error) Error() string {
 	)
 }
 
+// check returns an error type containing all errors found within the config
+// file.
 func (config *Dendrite) check(monolithic bool) error {
 	var problems []string
 
@@ -420,6 +459,7 @@ func (config *Dendrite) check(monolithic bool) error {
 	return nil
 }
 
+// absPath returns the absolute path for a given relative or absolute path.
 func absPath(dir string, path Path) string {
 	if filepath.IsAbs(string(path)) {
 		// filepath.Join cleans the path so we should clean the absolute paths as well for consistency.