login: implement logging in via browser

pkg/connector/login.go

@@ -27,6 +27,11 @@ const LoginStepIDComplete = "fi.mau.discord.login.complete"
 
 func (d *DiscordConnector) GetLoginFlows() []bridgev2.LoginFlow {
 	return []bridgev2.LoginFlow{
+		{
+			ID:          LoginFlowIDBrowser,
+			Name:        "Browser",
+			Description: "Log in to your Discord account in a web browser.",
+		},
 		{
 			ID:          LoginFlowIDRemoteAuth,
 			Name:        "QR Code",
@@ -46,6 +51,8 @@ func (d *DiscordConnector) CreateLogin(ctx context.Context, user *bridgev2.User,
 		return &DiscordTokenLogin{connector: d, User: user}, nil
 	case LoginFlowIDRemoteAuth:
 		return &DiscordRemoteAuthLogin{connector: d, User: user}, nil
+	case LoginFlowIDBrowser:
+		return &DiscordBrowserLogin{connector: d, User: user}, nil
 	default:
 		return nil, fmt.Errorf("unknown discord login flow id")
 	}

pkg/connector/login_browser.go

@@ -0,0 +1,156 @@
+// mautrix-discord - A Matrix-Discord puppeting bridge.
+// Copyright (C) 2024 Tulir Asokan
+//
+// 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 <https://www.gnu.org/licenses/>.
+
+package connector
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/bwmarrin/discordgo"
+	"github.com/rs/zerolog"
+	"maunium.net/go/mautrix/bridgev2"
+	"maunium.net/go/mautrix/bridgev2/database"
+	"maunium.net/go/mautrix/bridgev2/networkid"
+)
+
+const LoginFlowIDBrowser = "fi.mau.discord.login.browser"
+
+type DiscordBrowserLogin struct {
+	connector *DiscordConnector
+	User      *bridgev2.User
+
+	Session *discordgo.Session
+}
+
+var _ bridgev2.LoginProcessCookies = (*DiscordBrowserLogin)(nil)
+
+func (dl *DiscordBrowserLogin) softlyCloseSession() {
+	dl.User.Log.Debug().Msg("Closing session")
+	err := dl.Session.Close()
+	if err != nil {
+		dl.User.Log.Err(err).Msg("Couldn't close Discord session in response to login cancellation")
+	}
+}
+
+func (dl *DiscordBrowserLogin) Cancel() {
+}
+
+const ExtractDiscordTokenJS = `
+new Promise((resolve) => {
+	let mautrixDiscordTokenCheckInterval
+
+	const iframe = document.createElement('iframe')
+	document.head.append(iframe)
+
+	mautrixDiscordTokenCheckInterval = setInterval(() => {
+	  const token = iframe.contentWindow.localStorage.token
+	  if (token) {
+		resolve({ token: token.slice(1, -1) })
+		clearInterval(mautrixDiscordTokenCheckInterval)
+	  }
+	}, 200)
+})
+`
+
+func (dl *DiscordBrowserLogin) Start(ctx context.Context) (*bridgev2.LoginStep, error) {
+	return &bridgev2.LoginStep{
+		Type:         bridgev2.LoginStepTypeCookies,
+		StepID:       "fi.mau.discord.cookies",
+		Instructions: "Log in with Discord.",
+		CookiesParams: &bridgev2.LoginCookiesParams{
+			URL:       "https://discord.com/login",
+			UserAgent: "",
+			Fields: []bridgev2.LoginCookieField{{
+				ID:       "token",
+				Required: true,
+				Sources: []bridgev2.LoginCookieFieldSource{{
+					Type: bridgev2.LoginCookieTypeSpecial,
+					Name: "fi.mau.discord.token",
+				}},
+			}},
+			ExtractJS: ExtractDiscordTokenJS,
+		},
+	}, nil
+}
+
+func (dl *DiscordBrowserLogin) SubmitCookies(ctx context.Context, cookies map[string]string) (*bridgev2.LoginStep, error) {
+	log := zerolog.Ctx(ctx)
+
+	token := cookies["token"]
+	if token == "" {
+		log.Error().Msg("Received empty token")
+		return nil, fmt.Errorf("received empty token")
+	}
+	log.Debug().Msg("Logging in with submitted cookie")
+
+	// FIXME FIXME: The rest of this method is basically copy and pasted from
+	// DiscordTokenLogin, so find a way to tidy this up.
+
+	session, err := NewDiscordSession(ctx, token)
+	if err != nil {
+		return nil, fmt.Errorf("couldn't create discord session: %w", err)
+	}
+
+	client := DiscordClient{
+		connector: dl.connector,
+		Session:   session,
+	}
+	client.SetUp(ctx, nil)
+	err = client.connect(ctx)
+	if err != nil {
+		dl.softlyCloseSession()
+		return nil, err
+	}
+	// At this point we've opened a WebSocket connection to the gateway, received
+	// a READY packet, and know who we are.
+	user := session.State.User
+
+	dl.Session = session
+	ul, err := dl.User.NewLogin(ctx, &database.UserLogin{
+		ID: networkid.UserLoginID(user.ID),
+		Metadata: &UserLoginMetadata{
+			Token:            token,
+			HeartbeatSession: session.HeartbeatSession,
+		},
+	}, &bridgev2.NewLoginParams{
+		LoadUserLogin: func(ctx context.Context, login *bridgev2.UserLogin) error {
+			login.Client = &client
+			client.UserLogin = login
+
+			// Only now that we have a UserLogin can we begin syncing.
+			client.BeginSyncingIfUserLoginPresent(ctx)
+			return nil
+		},
+		DeleteOnConflict:  true,
+		DontReuseExisting: false,
+	})
+	if err != nil {
+		dl.softlyCloseSession()
+		return nil, fmt.Errorf("couldn't create login: %w", err)
+	}
+	zerolog.Ctx(ctx).Info().Str("user_id", user.ID).Str("user_username", user.Username).Msg("Connected to Discord during login")
+
+	return &bridgev2.LoginStep{
+		Type:         bridgev2.LoginStepTypeComplete,
+		StepID:       LoginStepIDComplete,
+		Instructions: fmt.Sprintf("Logged in as %s", user),
+		CompleteParams: &bridgev2.LoginCompleteParams{
+			UserLoginID: ul.ID,
+			UserLogin:   ul,
+		},
+	}, nil
+}