mirror of
https://github.com/oauth2-proxy/oauth2-proxy.git
synced 2024-11-28 09:08:44 +02:00
325 lines
8.6 KiB
Go
325 lines
8.6 KiB
Go
package providers
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import (
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"bytes"
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"encoding/base64"
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"encoding/json"
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"errors"
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"fmt"
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"io"
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"io/ioutil"
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"log"
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"net/http"
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"net/url"
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"strings"
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"time"
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"golang.org/x/oauth2"
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"golang.org/x/oauth2/google"
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admin "google.golang.org/api/admin/directory/v1"
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"google.golang.org/api/googleapi"
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)
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// GoogleProvider represents an Google based Identity Provider
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type GoogleProvider struct {
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*ProviderData
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RedeemRefreshURL *url.URL
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// GroupValidator is a function that determines if the passed email is in
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// the configured Google group.
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GroupValidator func(string) bool
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}
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// NewGoogleProvider initiates a new GoogleProvider
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func NewGoogleProvider(p *ProviderData) *GoogleProvider {
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p.ProviderName = "Google"
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if p.LoginURL.String() == "" {
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p.LoginURL = &url.URL{Scheme: "https",
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Host: "accounts.google.com",
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Path: "/o/oauth2/auth",
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// to get a refresh token. see https://developers.google.com/identity/protocols/OAuth2WebServer#offline
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RawQuery: "access_type=offline",
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}
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}
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if p.RedeemURL.String() == "" {
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p.RedeemURL = &url.URL{Scheme: "https",
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Host: "www.googleapis.com",
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Path: "/oauth2/v3/token"}
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}
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if p.ValidateURL.String() == "" {
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p.ValidateURL = &url.URL{Scheme: "https",
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Host: "www.googleapis.com",
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Path: "/oauth2/v1/tokeninfo"}
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}
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if p.Scope == "" {
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p.Scope = "profile email"
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}
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return &GoogleProvider{
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ProviderData: p,
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// Set a default GroupValidator to just always return valid (true), it will
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// be overwritten if we configured a Google group restriction.
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GroupValidator: func(email string) bool {
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return true
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},
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}
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}
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func emailFromIDToken(idToken string) (string, error) {
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// id_token is a base64 encode ID token payload
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// https://developers.google.com/accounts/docs/OAuth2Login#obtainuserinfo
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jwt := strings.Split(idToken, ".")
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jwtData := strings.TrimSuffix(jwt[1], "=")
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b, err := base64.RawURLEncoding.DecodeString(jwtData)
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if err != nil {
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return "", err
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}
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var email struct {
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Email string `json:"email"`
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EmailVerified bool `json:"email_verified"`
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}
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err = json.Unmarshal(b, &email)
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if err != nil {
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return "", err
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}
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if email.Email == "" {
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return "", errors.New("missing email")
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}
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if !email.EmailVerified {
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return "", fmt.Errorf("email %s not listed as verified", email.Email)
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}
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return email.Email, nil
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}
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// Redeem exchanges the OAuth2 authentication token for an ID token
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func (p *GoogleProvider) Redeem(redirectURL, code string) (s *SessionState, err error) {
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if code == "" {
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err = errors.New("missing code")
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return
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}
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params := url.Values{}
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params.Add("redirect_uri", redirectURL)
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params.Add("client_id", p.ClientID)
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params.Add("client_secret", p.ClientSecret)
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params.Add("code", code)
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params.Add("grant_type", "authorization_code")
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var req *http.Request
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req, err = http.NewRequest("POST", p.RedeemURL.String(), bytes.NewBufferString(params.Encode()))
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if err != nil {
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return
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}
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req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
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resp, err := http.DefaultClient.Do(req)
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if err != nil {
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return
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}
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var body []byte
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body, err = ioutil.ReadAll(resp.Body)
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resp.Body.Close()
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if err != nil {
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return
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}
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if resp.StatusCode != 200 {
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err = fmt.Errorf("got %d from %q %s", resp.StatusCode, p.RedeemURL.String(), body)
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return
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}
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var jsonResponse struct {
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AccessToken string `json:"access_token"`
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RefreshToken string `json:"refresh_token"`
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ExpiresIn int64 `json:"expires_in"`
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IDToken string `json:"id_token"`
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}
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err = json.Unmarshal(body, &jsonResponse)
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if err != nil {
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return
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}
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var email string
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email, err = emailFromIDToken(jsonResponse.IDToken)
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if err != nil {
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return
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}
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s = &SessionState{
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AccessToken: jsonResponse.AccessToken,
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IDToken: jsonResponse.IDToken,
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ExpiresOn: time.Now().Add(time.Duration(jsonResponse.ExpiresIn) * time.Second).Truncate(time.Second),
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RefreshToken: jsonResponse.RefreshToken,
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Email: email,
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}
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return
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}
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// SetGroupRestriction configures the GoogleProvider to restrict access to the
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// specified group(s). AdminEmail has to be an administrative email on the domain that is
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// checked. CredentialsFile is the path to a json file containing a Google service
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// account credentials.
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func (p *GoogleProvider) SetGroupRestriction(groups []string, adminEmail string, credentialsReader io.Reader) {
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adminService := getAdminService(adminEmail, credentialsReader)
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p.GroupValidator = func(email string) bool {
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return userInGroup(adminService, groups, email)
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}
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}
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func getAdminService(adminEmail string, credentialsReader io.Reader) *admin.Service {
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data, err := ioutil.ReadAll(credentialsReader)
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if err != nil {
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log.Fatal("can't read Google credentials file:", err)
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}
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conf, err := google.JWTConfigFromJSON(data, admin.AdminDirectoryUserReadonlyScope, admin.AdminDirectoryGroupReadonlyScope)
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if err != nil {
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log.Fatal("can't load Google credentials file:", err)
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}
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conf.Subject = adminEmail
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client := conf.Client(oauth2.NoContext)
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adminService, err := admin.New(client)
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if err != nil {
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log.Fatal(err)
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}
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return adminService
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}
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func userInGroup(service *admin.Service, groups []string, email string) bool {
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user, err := fetchUser(service, email)
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if err != nil {
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log.Printf("error fetching user: %v", err)
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return false
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}
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id := user.Id
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custID := user.CustomerId
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for _, group := range groups {
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members, err := fetchGroupMembers(service, group)
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if err != nil {
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if err, ok := err.(*googleapi.Error); ok && err.Code == 404 {
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log.Printf("error fetching members for group %s: group does not exist", group)
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} else {
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log.Printf("error fetching group members: %v", err)
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return false
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}
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}
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for _, member := range members {
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switch member.Type {
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case "CUSTOMER":
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if member.Id == custID {
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return true
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}
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case "USER":
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if member.Id == id {
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return true
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}
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}
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}
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}
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return false
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}
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func fetchUser(service *admin.Service, email string) (*admin.User, error) {
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user, err := service.Users.Get(email).Do()
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return user, err
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}
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func fetchGroupMembers(service *admin.Service, group string) ([]*admin.Member, error) {
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members := []*admin.Member{}
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pageToken := ""
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for {
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req := service.Members.List(group)
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if pageToken != "" {
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req.PageToken(pageToken)
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}
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r, err := req.Do()
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if err != nil {
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return nil, err
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}
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for _, member := range r.Members {
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members = append(members, member)
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}
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if r.NextPageToken == "" {
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break
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}
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pageToken = r.NextPageToken
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}
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return members, nil
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}
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// ValidateGroup validates that the provided email exists in the configured Google
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// group(s).
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func (p *GoogleProvider) ValidateGroup(email string) bool {
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return p.GroupValidator(email)
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}
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// RefreshSessionIfNeeded checks if the session has expired and uses the
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// RefreshToken to fetch a new ID token if required
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func (p *GoogleProvider) RefreshSessionIfNeeded(s *SessionState) (bool, error) {
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if s == nil || s.ExpiresOn.After(time.Now()) || s.RefreshToken == "" {
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return false, nil
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}
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newToken, newIDToken, duration, err := p.redeemRefreshToken(s.RefreshToken)
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if err != nil {
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return false, err
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}
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// re-check that the user is in the proper google group(s)
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if !p.ValidateGroup(s.Email) {
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return false, fmt.Errorf("%s is no longer in the group(s)", s.Email)
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}
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origExpiration := s.ExpiresOn
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s.AccessToken = newToken
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s.IDToken = newIDToken
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s.ExpiresOn = time.Now().Add(duration).Truncate(time.Second)
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log.Printf("refreshed access token %s (expired on %s)", s, origExpiration)
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return true, nil
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}
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func (p *GoogleProvider) redeemRefreshToken(refreshToken string) (token string, idToken string, expires time.Duration, err error) {
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// https://developers.google.com/identity/protocols/OAuth2WebServer#refresh
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params := url.Values{}
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params.Add("client_id", p.ClientID)
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params.Add("client_secret", p.ClientSecret)
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params.Add("refresh_token", refreshToken)
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params.Add("grant_type", "refresh_token")
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var req *http.Request
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req, err = http.NewRequest("POST", p.RedeemURL.String(), bytes.NewBufferString(params.Encode()))
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if err != nil {
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return
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}
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req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
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resp, err := http.DefaultClient.Do(req)
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if err != nil {
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return
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}
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var body []byte
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body, err = ioutil.ReadAll(resp.Body)
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resp.Body.Close()
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if err != nil {
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return
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}
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if resp.StatusCode != 200 {
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err = fmt.Errorf("got %d from %q %s", resp.StatusCode, p.RedeemURL.String(), body)
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return
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}
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var data struct {
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AccessToken string `json:"access_token"`
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ExpiresIn int64 `json:"expires_in"`
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IDToken string `json:"id_token"`
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}
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err = json.Unmarshal(body, &data)
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if err != nil {
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return
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}
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token = data.AccessToken
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idToken = data.IDToken
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expires = time.Duration(data.ExpiresIn) * time.Second
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return
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}
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