98 lines
2.4 KiB
Go
98 lines
2.4 KiB
Go
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/*
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* Copyright IDMesh Authors
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package main
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import (
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"errors"
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"fmt"
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"log"
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"net/http"
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)
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const (
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CookieKeyIDMeshUserID = "IDMesh-User-Id"
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)
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type Config struct {
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// MUST, default redirect url
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DefaultRedirectURL string `json:"default_redirect_url"`
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// OPTIONAL, map[user_id]redirect_url, fallback: default_redirect_url
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Rules map[string]string `json:"rules"`
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}
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func (cfg *Config) Validate() error {
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if cfg.DefaultRedirectURL == "" {
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return errors.New("empty `default_redirect_url`")
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}
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return nil
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}
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type RelayServer struct {
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cfg *Config
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}
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func NewRelayServer(cfg Config) (http.Handler, error) {
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if err := cfg.Validate(); err != nil {
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return nil, err
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}
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return &RelayServer{cfg: &cfg}, nil
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}
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func (s *RelayServer) ServeHTTP(w http.ResponseWriter, r *http.Request) {
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switch r.URL.Path {
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case "", "/":
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uid, err := s.readUserID(r)
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if err != nil {
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log.Println(err)
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s.redirect(w, s.cfg.DefaultRedirectURL)
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return
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}
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loc, ok := s.cfg.Rules[uid]
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if !ok {
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log.Println("unexpected uid:", uid, ", fallback to default url:", s.cfg.DefaultRedirectURL)
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s.redirect(w, s.cfg.DefaultRedirectURL)
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return
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}
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s.redirect(w, loc)
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default:
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w.WriteHeader(http.StatusNotFound)
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}
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}
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func (s *RelayServer) redirect(w http.ResponseWriter, loc string) {
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nr, err := http.NewRequest(http.MethodGet, loc, nil)
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if err != nil {
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log.Printf("fail to make request: %v", err)
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w.WriteHeader(http.StatusInternalServerError)
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w.Write([]byte("internal error"))
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return
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}
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http.Redirect(w, nr, loc, http.StatusFound)
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}
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func (s *RelayServer) readUserID(r *http.Request) (string, error) {
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c, err := r.Cookie(CookieKeyIDMeshUserID)
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if err != nil {
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if errors.Is(err, http.ErrNoCookie) {
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return "", fmt.Errorf("read user: cookie %q not found", CookieKeyIDMeshUserID)
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}
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return "", fmt.Errorf("read user: fail to read cookie: %v", err)
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}
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return c.Value, nil
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}
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