gotosocial/internal/oidc/idp.go

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/*
GoToSocial
Copyright (C) 2021 GoToSocial Authors admin@gotosocial.org
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Affero General Public License for more details.
You should have received a copy of the GNU Affero General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package oidc
import (
"context"
"fmt"
"github.com/coreos/go-oidc/v3/oidc"
"github.com/superseriousbusiness/gotosocial/internal/config"
"golang.org/x/oauth2"
)
const (
// CallbackPath is the API path for receiving callback tokens from external OIDC providers
CallbackPath = "/auth/callback"
)
// IDP contains logic for parsing an OIDC access code into a set of claims by calling an external OIDC provider.
type IDP interface {
// HandleCallback accepts a context (pass the context from the http.Request), and an oauth2 code as returned from a successful
// login through an OIDC provider. It uses the code to request a token from the OIDC provider, which should contain an id_token
// with a set of claims.
//
// Note that this function *does not* verify state. That should be handled by the caller *before* this function is called.
HandleCallback(ctx context.Context, code string) (*Claims, error)
// AuthCodeURL returns the proper redirect URL for this IDP, for redirecting requesters to the correct OIDC endpoint.
AuthCodeURL(state string) string
}
type idp struct {
oauth2Config oauth2.Config
provider *oidc.Provider
oidcConf *oidc.Config
}
// NewIDP returns a new IDP configured with the given config.
// If the passed config contains a nil value for the OIDCConfig, or OIDCConfig.Enabled
// is set to false, then nil, nil will be returned. If OIDCConfig.Enabled is true,
// then the other OIDC config fields must also be set.
func NewIDP(ctx context.Context, config *config.Config) (IDP, error) {
// oidc isn't enabled so we don't need to do anything
if config.OIDCConfig == nil || !config.OIDCConfig.Enabled {
return nil, nil
}
// validate config fields
if config.OIDCConfig.IDPName == "" {
return nil, fmt.Errorf("not set: IDPName")
}
if config.OIDCConfig.Issuer == "" {
return nil, fmt.Errorf("not set: Issuer")
}
if config.OIDCConfig.ClientID == "" {
return nil, fmt.Errorf("not set: ClientID")
}
if config.OIDCConfig.ClientSecret == "" {
return nil, fmt.Errorf("not set: ClientSecret")
}
if len(config.OIDCConfig.Scopes) == 0 {
return nil, fmt.Errorf("not set: Scopes")
}
provider, err := oidc.NewProvider(ctx, config.OIDCConfig.Issuer)
if err != nil {
return nil, err
}
oauth2Config := oauth2.Config{
// client_id and client_secret of the client.
ClientID: config.OIDCConfig.ClientID,
ClientSecret: config.OIDCConfig.ClientSecret,
// The redirectURL.
RedirectURL: fmt.Sprintf("%s://%s%s", config.Protocol, config.Host, CallbackPath),
// Discovery returns the OAuth2 endpoints.
Endpoint: provider.Endpoint(),
// "openid" is a required scope for OpenID Connect flows.
//
// Other scopes, such as "groups" can be requested.
Scopes: config.OIDCConfig.Scopes,
}
// create a config for verifier creation
oidcConf := &oidc.Config{
ClientID: config.OIDCConfig.ClientID,
}
if config.OIDCConfig.SkipVerification {
oidcConf.SkipClientIDCheck = true
oidcConf.SkipExpiryCheck = true
oidcConf.SkipIssuerCheck = true
}
return &idp{
oauth2Config: oauth2Config,
oidcConf: oidcConf,
provider: provider,
}, nil
}