Add macaroon token handlers

src/github.com/matrix-org/dendrite/clientapi/auth/tokens/tokens_handlers.go

@@ -0,0 +1,115 @@
+// 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 tokens
+
+import (
+	"errors"
+	"net/http"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/matrix-org/dendrite/clientapi/jsonerror"
+	"github.com/matrix-org/util"
+)
+
+// GetUserFromToken returns the user associated with the token
+// Returns the error if something goes wrong.
+// Warning: Does not validate the token. Use ValidateToken for that.
+func GetUserFromToken(token string) (user string, err error) {
+	mac, err := deSerializeMacaroon(token)
+	if err != nil {
+		return
+	}
+
+	user = string(mac.Id()[:])
+	return
+}
+
+// ValidateToken validates that the Token is understood and was signed by this server.
+// Returns nil if token is valid, otherwise returns a error response which can be sent to client.
+func ValidateToken(op TokenOptions, token string) *util.JSONResponse {
+	macaroon, err := deSerializeMacaroon(token)
+	if err != nil {
+		return &util.JSONResponse{
+			Code: http.StatusUnauthorized,
+			JSON: jsonerror.UnknownToken("Token does not represent a valid macaroon"),
+		}
+	}
+
+	caveats, err := macaroon.VerifySignature(op.ServerPrivateKey, nil)
+	if err != nil {
+		return &util.JSONResponse{
+			Code: http.StatusUnauthorized,
+			JSON: jsonerror.UnknownToken("Provided token was not issued by this server"),
+		}
+	}
+
+	err = verifyCaveats(caveats, op.UserID)
+	if err != nil {
+		return &util.JSONResponse{
+			Code: http.StatusForbidden,
+			JSON: jsonerror.Forbidden("Provided token not authorized"),
+		}
+	}
+	return nil
+}
+
+// verifyCaveats verifies caveats associated with a login token macaroon.
+// which are "gen = 1", "user_id = ...", "time < ..."
+// Returns nil on successful verification, else returns an error.
+func verifyCaveats(caveats []string, userID string) error {
+	// variable verified represents a bitmap
+	// last 4 bit is Uvvv where,
+	// U: unknownCaveat
+	// v: caveat to be verified
+	var verified uint8
+	now := time.Now().Second()
+
+LoopCaveat:
+	for _, caveat := range caveats {
+		switch {
+		case caveat == Gen:
+			verified |= 1
+		case strings.HasPrefix(caveat, UserPrefix):
+			if caveat[len(UserPrefix):] == userID {
+				verified |= 2
+			}
+		case strings.HasPrefix(caveat, TimePrefix):
+			if verifyExpiry(caveat[len(TimePrefix):], now) {
+				verified |= 4
+			}
+		default:
+			verified |= 8
+			break LoopCaveat
+		}
+	}
+	// Check that all three caveats are verified and no extra caveats
+	// i.e. Uvvv == 0111
+	if verified == 7 {
+		return nil
+	} else if verified >= 8 {
+		return errors.New("Unknown caveat present")
+	}
+
+	return errors.New("Required caveats not present")
+}
+
+func verifyExpiry(t string, now int) bool {
+	expiry, err := strconv.Atoi(t)
+
+	if err != nil {
+		return false
+	}
+	return now < expiry
+}

src/github.com/matrix-org/dendrite/clientapi/auth/tokens/tokens_handlers_test.go

@@ -0,0 +1,56 @@
+// 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 tokens
+
+import "testing"
+
+// If any of these options are missing, validation should fail
+var invalidMissings = []string{"ServerPrivateKey", "UserID"}
+
+func TestValidateToken(t *testing.T) {
+	fakeToken, err := GenerateLoginToken(validTokenOp)
+	if err != nil {
+		t.Errorf("Token generation failed for valid TokenOptions with err: %s", err.Error())
+	}
+
+	// Test validation
+	res := ValidateToken(validTokenOp, fakeToken)
+	if res != nil {
+		t.Error("Token validation failed with response: ", *res)
+	}
+
+	// Test validation fails for invalid TokenOp
+	for _, invalidMissing := range invalidMissings {
+		res = ValidateToken(invalidTokenOps[invalidMissing], fakeToken)
+		if res == nil {
+			t.Errorf("Token validation should fail for TokenOptions with missing %s", invalidMissing)
+		}
+	}
+}
+
+func TestGetUserFromToken(t *testing.T) {
+	fakeToken, err := GenerateLoginToken(validTokenOp)
+	if err != nil {
+		t.Errorf("Token generation failed for valid TokenOptions with err: %s", err.Error())
+	}
+
+	// Test validation
+	name, err := GetUserFromToken(fakeToken)
+	if err != nil {
+		t.Error("Failed to get userID from Token: ", err)
+	}
+
+	if name != validTokenOp.UserID {
+		t.Error("UserID from Token doesn't match, got: ", name, " expected: ", validTokenOp.UserID)
+	}
+}