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// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements. See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership. The ASF licenses this file
// to you 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 session
import (
"context"
"encoding/base64"
"fmt"
"net/http"
"github.com/apache/arrow-go/v18/arrow/flight"
"google.golang.org/protobuf/proto"
)
const StatelessSessionCookieName string = "arrow_flight_session"
// NewStatelessServerSessionManager creates a new StatelessServerSessionManager.
//
// The tokens it produces contain the entire session state, so sessions can
// be maintained across multiple backends.
// Token contents are considered opaque but are NOT encrypted.
func NewStatelessServerSessionManager() *statelessServerSessionManager {
return &statelessServerSessionManager{}
}
type statelessServerSessionManager struct{}
func (manager *statelessServerSessionManager) CreateSession(ctx context.Context) (ServerSession, error) {
return NewStatelessServerSession(nil), nil
}
func (manager *statelessServerSessionManager) GetSession(ctx context.Context) (ServerSession, error) {
session, err := GetSessionFromContext(ctx)
if err == nil {
return session, nil
}
session, err = getSessionFromIncomingCookie(ctx)
if err == nil {
return session, err
}
if err == http.ErrNoCookie {
return nil, ErrNoSession
}
return nil, fmt.Errorf("failed to get current session from cookie: %w", err)
}
func (manager *statelessServerSessionManager) CloseSession(session ServerSession) error {
return nil
}
// NewStatelessServerSession creates a new instance of a server session that can serialize its entire state.
// A map is provided containing the initial state. If it is nil, a new empty state will be created.
func NewStatelessServerSession(options map[string]*flight.SessionOptionValue) *statelessServerSession {
if options == nil {
options = make(map[string]*flight.SessionOptionValue)
}
return &statelessServerSession{
serverSession: serverSession{options: options},
}
}
type statelessServerSession struct {
serverSession
}
// First encode session contents using protobuf binary marshaller.
// Then base64 encode the resulting bytes for client compatibility.
func (session *statelessServerSession) Token() string {
session.mu.RLock()
defer session.mu.RUnlock()
payload := flight.GetSessionOptionsResult{SessionOptions: session.options}
b, err := proto.Marshal(&payload)
if err != nil {
panic(fmt.Sprintf("failed to marshal stateless token: %s", err))
}
return base64.StdEncoding.EncodeToString(b)
}
// Reconstruct the session from its fully encoded token representation
func decodeStatelessToken(token string) (*statelessServerSession, error) {
decoded, err := base64.StdEncoding.DecodeString(token)
if err != nil {
return nil, err
}
var parsed flight.GetSessionOptionsResult
if err := proto.Unmarshal(decoded, &parsed); err != nil {
return nil, err
}
return NewStatelessServerSession(parsed.SessionOptions), nil
}
// Check the provided context for a cookie in the incoming gRPC metadata containing the
// stateless session token. Decode the token payload to reconstruct the session.
func getSessionFromIncomingCookie(ctx context.Context) (*statelessServerSession, error) {
cookie, err := GetIncomingCookieByName(ctx, StatelessSessionCookieName)
if err != nil {
return nil, err
}
return decodeStatelessToken(cookie.Value)
}
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