Add Discord account linking

src/config/types.go

@@ -67,6 +67,11 @@ type DiscordConfig struct {
 	BotToken  string
 	BotUserID string
 
+	OAuthClientID     string
+	OAuthClientSecret string
+
+	GuildID           string
+	MemberRoleID      string
 	ShowcaseChannelID string
 	LibraryChannelID  string
 }

src/discord/payloads.go

@@ -220,7 +220,9 @@ type User struct {
 	ID            string  `json:"id"`
 	Username      string  `json:"username"`
 	Discriminator string  `json:"discriminator"`
+	Avatar        *string `json:"avatar"`
 	IsBot         bool    `json:"bot"`
+	Locale        string  `json:"locale"`
 }
 
 func UserFromMap(m interface{}) User {

src/discord/rest.go

@@ -8,6 +8,8 @@ import (
 	"io"
 	"net/http"
 	"net/http/httputil"
+	"net/url"
+	"strings"
 
 	"git.handmade.network/hmn/hmn/src/config"
 	"git.handmade.network/hmn/hmn/src/logging"
@@ -26,13 +28,17 @@ var UserAgent = fmt.Sprintf("%s (%s, %s)", BotName, UserAgentURL, UserAgentVersi
 
 var httpClient = &http.Client{}
 
+func buildUrl(path string) string {
+	return fmt.Sprintf("%s%s", BaseUrl, path)
+}
+
 func makeRequest(ctx context.Context, method string, path string, body []byte) *http.Request {
 	var bodyReader io.Reader
 	if body != nil {
 		bodyReader = bytes.NewBuffer(body)
 	}
 
-	req, err := http.NewRequestWithContext(ctx, method, fmt.Sprintf("%s%s", BaseUrl, path), bodyReader)
+	req, err := http.NewRequestWithContext(ctx, method, buildUrl(path), bodyReader)
 	if err != nil {
 		panic(err)
 	}
@@ -171,6 +177,121 @@ func CreateDM(ctx context.Context, recipientID string) (*Channel, error) {
 	return &channel, nil
 }
 
+type OAuthCodeExchangeResponse struct {
+	AccessToken  string `json:"access_token"`
+	TokenType    string `json:"token_type"`
+	ExpiresIn    int    `json:"expires_in"`
+	RefreshToken string `json:"refresh_token"`
+	Scope        string `json:"scope"`
+}
+
+func ExchangeOAuthCode(ctx context.Context, code, redirectURI string) (*OAuthCodeExchangeResponse, error) {
+	const name = "OAuth Code Exchange"
+
+	body := make(url.Values)
+	body.Set("client_id", config.Config.Discord.OAuthClientID)
+	body.Set("client_secret", config.Config.Discord.OAuthClientSecret)
+	body.Set("grant_type", "authorization_code")
+	body.Set("code", code)
+	body.Set("redirect_uri", redirectURI)
+	bodyStr := body.Encode()
+
+	res, err := doWithRateLimiting(ctx, name, func(ctx context.Context) *http.Request {
+		req, err := http.NewRequestWithContext(
+			ctx,
+			http.MethodPost,
+			"https://discord.com/api/oauth2/token",
+			strings.NewReader(bodyStr),
+		)
+		if err != nil {
+			panic(err)
+		}
+		req.Header.Add("User-Agent", UserAgent)
+		req.Header.Add("Content-Type", "application/x-www-form-urlencoded")
+
+		return req
+	})
+	if err != nil {
+		return nil, err
+	}
+	defer res.Body.Close()
+
+	if res.StatusCode >= 400 {
+		logErrorResponse(ctx, name, res, "")
+		return nil, oops.New(nil, "received error from Discord")
+	}
+
+	bodyBytes, err := io.ReadAll(res.Body)
+	if err != nil {
+		panic(err)
+	}
+
+	var tokenResponse OAuthCodeExchangeResponse
+	err = json.Unmarshal(bodyBytes, &tokenResponse)
+	if err != nil {
+		return nil, oops.New(err, "failed to unmarshal Discord OAuth token")
+	}
+
+	return &tokenResponse, nil
+}
+
+func GetCurrentUserAsOAuth(ctx context.Context, accessToken string) (*User, error) {
+	const name = "Get Current User"
+
+	res, err := doWithRateLimiting(ctx, name, func(ctx context.Context) *http.Request {
+		req, err := http.NewRequestWithContext(ctx, http.MethodGet, buildUrl("/users/@me"), nil)
+		if err != nil {
+			panic(err)
+		}
+		req.Header.Add("Authorization", fmt.Sprintf("Bearer %s", accessToken))
+		req.Header.Add("User-Agent", UserAgent)
+
+		return req
+	})
+	if err != nil {
+		return nil, err
+	}
+	defer res.Body.Close()
+
+	if res.StatusCode >= 400 {
+		logErrorResponse(ctx, name, res, "")
+		return nil, oops.New(nil, "received error from Discord")
+	}
+
+	bodyBytes, err := io.ReadAll(res.Body)
+	if err != nil {
+		panic(err)
+	}
+
+	var user User
+	err = json.Unmarshal(bodyBytes, &user)
+	if err != nil {
+		return nil, oops.New(err, "failed to unmarshal Discord user")
+	}
+
+	return &user, nil
+}
+
+func AddGuildMemberRole(ctx context.Context, userID, roleID string) error {
+	const name = "Delete Message"
+
+	path := fmt.Sprintf("/guilds/%s/members/%s/roles/%s", config.Config.Discord.GuildID, userID, roleID)
+	res, err := doWithRateLimiting(ctx, name, func(ctx context.Context) *http.Request {
+		return makeRequest(ctx, http.MethodPut, path, nil)
+	})
+	if err != nil {
+		return err
+	}
+	defer res.Body.Close()
+
+	if res.StatusCode != http.StatusNoContent {
+		logErrorResponse(ctx, name, res, "")
+		return oops.New(nil, "got unexpected status code when adding role")
+	}
+
+	return nil
+}
+
 func logErrorResponse(ctx context.Context, name string, res *http.Response, msg string) {
 	dump, err := httputil.DumpResponse(res, true)
 	if err != nil {

src/hmnurl/urls.go

@@ -545,6 +545,22 @@ func BuildLibraryResource(projectSlug string, resourceId int) string {
 	return ProjectUrl(builder.String(), nil, projectSlug)
 }
 
+/*
+* Discord OAuth
+ */
+
+var RegexDiscordTest = regexp.MustCompile("^/discord$")
+
+func BuildDiscordTest() string {
+	return Url("/discord", nil)
+}
+
+var RegexDiscordOAuthCallback = regexp.MustCompile("^/_discord_callback$")
+
+func BuildDiscordOAuthCallback() string {
+	return Url("/_discord_callback", nil)
+}
+
 /*
 * Assets
  */

src/migration/migrations/2021-08-16T023440Z_DiscordData.go

@@ -0,0 +1,76 @@
+package migrations
+
+import (
+	"context"
+	"time"
+
+	"git.handmade.network/hmn/hmn/src/migration/types"
+	"git.handmade.network/hmn/hmn/src/oops"
+	"github.com/jackc/pgx/v4"
+)
+
+func init() {
+	registerMigration(DiscordData{})
+}
+
+type DiscordData struct{}
+
+func (m DiscordData) Version() types.MigrationVersion {
+	return types.MigrationVersion(time.Date(2021, 8, 16, 2, 34, 40, 0, time.UTC))
+}
+
+func (m DiscordData) Name() string {
+	return "DiscordData"
+}
+
+func (m DiscordData) Description() string {
+	return "Clean up Discord data models"
+}
+
+func (m DiscordData) Up(ctx context.Context, tx pgx.Tx) error {
+	_, err := tx.Exec(ctx, `
+		ALTER TABLE handmade_discord RENAME TO handmade_discorduser;
+		ALTER TABLE handmade_discorduser
+			ALTER username SET NOT NULL,
+			ALTER discriminator SET NOT NULL,
+			ALTER access_token SET NOT NULL,
+			ALTER refresh_token SET NOT NULL,
+			ALTER locale SET NOT NULL,
+			ALTER userid SET NOT NULL,
+			ALTER expiry SET NOT NULL;
+	`)
+	if err != nil {
+		return oops.New(err, "failed to fix up discord table")
+	}
+
+	_, err = tx.Exec(ctx, `
+		ALTER TABLE handmade_discordmessagecontent
+			DROP CONSTRAINT handmade_discordmess_discord_id_1acc147f_fk_handmade_,
+			DROP CONSTRAINT handmade_discordmess_message_id_4dfde67d_fk_handmade_,
+			ADD FOREIGN KEY (discord_id) REFERENCES handmade_discorduser (id) ON DELETE CASCADE,
+			ADD FOREIGN KEY (message_id) REFERENCES handmade_discordmessage (id) ON DELETE CASCADE;
+		
+		ALTER TABLE handmade_discordmessageattachment
+			DROP CONSTRAINT handmade_discordmess_asset_id_c64a3c31_fk_handmade_,
+			DROP CONSTRAINT handmade_discordmess_message_id_d39da9b3_fk_handmade_,
+			ADD FOREIGN KEY (asset_id) REFERENCES handmade_asset (id) ON DELETE CASCADE,
+			ADD FOREIGN KEY (message_id) REFERENCES handmade_discordmessage (id) ON DELETE CASCADE;
+		
+		ALTER TABLE handmade_discordmessageembed
+			DROP CONSTRAINT handmade_discordmess_image_id_9b04bb5f_fk_handmade_,
+			DROP CONSTRAINT handmade_discordmess_message_id_04f15ce6_fk_handmade_,
+			DROP CONSTRAINT handmade_discordmess_video_id_1c41289f_fk_handmade_,
+			ADD FOREIGN KEY (image_id) REFERENCES handmade_asset (id) ON DELETE SET NULL,
+			ADD FOREIGN KEY (message_id) REFERENCES handmade_discordmessage (id) ON DELETE CASCADE,
+			ADD FOREIGN KEY (video_id) REFERENCES handmade_asset (id) ON DELETE SET NULL;
+	`)
+	if err != nil {
+		return oops.New(err, "failed to fix constraints")
+	}
+
+	return nil
+}
+
+func (m DiscordData) Down(ctx context.Context, tx pgx.Tx) error {
+	panic("Implement me")
+}

src/models/discord.go

@@ -2,8 +2,65 @@ package models
 
 import (
 	"time"
+
+	"github.com/google/uuid"
 )
 
+type DiscordUser struct {
+	ID            int       `db:"id"`
+	Username      string    `db:"username"`
+	Discriminator string    `db:"discriminator"`
+	AccessToken   string    `db:"access_token"`
+	RefreshToken  string    `db:"refresh_token"`
+	Avatar        *string   `db:"avatar"`
+	Locale        string    `db:"locale"`
+	UserID        string    `db:"userid"`
+	Expiry        time.Time `db:"expiry"`
+	HMNUserId     int       `db:"hmn_user_id"`
+}
+
+/*
+Logs the existence of a Discord message and what we've done with it.
+Created unconditionally for all users, regardless of link status.
+Therefore, it must not contain any actual content.
+*/
+type DiscordMessage struct {
+	ID             string    `db:"id"`
+	ChannelID      string    `db:"channel_id"`
+	GuildID        *string   `db:"guild_id"`
+	Url            string    `db:"url"`
+	UserID         string    `db:"user_id"`
+	SentAt         time.Time `db:"sent_at"`
+	SnippetCreated bool      `db:"snippet_created"`
+}
+
+/*
+Stores the content of a Discord message for users with a linked
+Discord account. Always created for users with a linked Discord
+account, regardless of whether we create snippets or not.
+*/
+type DiscordMessageContent struct {
+	MessageID   string `db:"message_id"`
+	LastContent string `db:"last_content"`
+	DiscordID   int    `db:"discord_id"`
+}
+
+type DiscordMessageAttachment struct {
+	ID        string    `db:"id"`
+	AssetID   uuid.UUID `db:"asset_id"`
+	MessageID string    `db:"message_id"`
+}
+
+type DiscordMessageEmbed struct {
+	ID          int        `db:"id"`
+	Title       *string    `db:"title"`
+	Description *string    `db:"description"`
+	URL         *string    `db:"url"`
+	ImageID     *uuid.UUID `db:"image_id"`
+	MessageID   string     `db:"message_id"`
+	VideoID     *uuid.UUID `db:"video_id"`
+}
+
 type DiscordSession struct {
 	ID             string `db:"session_id"`
 	SequenceNumber int    `db:"sequence_number"`
@@ -15,13 +72,3 @@ type DiscordOutgoingMessage struct {
 	PayloadJSON string    `db:"payload_json"`
 	ExpiresAt   time.Time `db:"expires_at"`
 }
-
-type DiscordMessage struct {
-	ID             string    `db:"id"`
-	ChannelID      string    `db:"channel_id"`
-	GuildID        *string   `db:"guild_id"`
-	Url            string    `db:"url"`
-	UserID         string    `db:"user_id"`
-	SentAt         time.Time `db:"sent_at"`
-	SnippetCreated bool      `db:"snippet_created"`
-}

src/templates/mapping.go

@@ -1,6 +1,7 @@
 package templates
 
 import (
+	"fmt"
 	"html/template"
 	"net"
 	"regexp"
@@ -331,6 +332,19 @@ func PodcastEpisodeToTemplate(projectSlug string, episode *models.PodcastEpisode
 	}
 }
 
+func DiscordUserToTemplate(d *models.DiscordUser) DiscordUser {
+	var avatarUrl string // TODO: Default avatar image
+	if d.Avatar != nil {
+		avatarUrl = fmt.Sprintf("https://cdn.discordapp.com/avatars/%s/%s.png", d.UserID, *d.Avatar)
+	}
+
+	return DiscordUser{
+		Username:      d.Username,
+		Discriminator: d.Discriminator,
+		Avatar:        avatarUrl,
+	}
+}
+
 func maybeString(s *string) string {
 	if s == nil {
 		return ""

src/templates/src/discordtest.html

@@ -0,0 +1,14 @@
+{{ template "base.html" . }}
+
+{{ define "content" }}
+Wow a discord
+
+<div>
+    {{ with .DiscordUser }}
+        <img src="{{ .Avatar }}">
+        {{ .Username }}#{{ .Discriminator }}
+    {{ else }}
+        <a href="{{ $.AuthorizeURL }}">Link your account</a>
+    {{ end }}
+</div>
+{{ end }}

src/templates/types.go

@@ -303,3 +303,9 @@ type EmailBaseData struct {
 	Subject   template.HTML
 	Separator template.HTML
 }
+
+type DiscordUser struct {
+	Username      string
+	Discriminator string
+	Avatar        string
+}

src/website/discord.go

@@ -0,0 +1,140 @@
+package website
+
+import (
+	"errors"
+	"fmt"
+	"net/http"
+	"net/url"
+	"time"
+
+	"git.handmade.network/hmn/hmn/src/auth"
+	"git.handmade.network/hmn/hmn/src/config"
+	"git.handmade.network/hmn/hmn/src/db"
+	"git.handmade.network/hmn/hmn/src/discord"
+	"git.handmade.network/hmn/hmn/src/hmnurl"
+	"git.handmade.network/hmn/hmn/src/models"
+	"git.handmade.network/hmn/hmn/src/oops"
+	"git.handmade.network/hmn/hmn/src/templates"
+)
+
+func DiscordTest(c *RequestContext) ResponseData {
+	var userDiscord *models.DiscordUser
+	iUserDiscord, err := db.QueryOne(c.Context(), c.Conn, models.DiscordUser{},
+		`
+		SELECT $columns
+		FROM handmade_discorduser
+		WHERE hmn_user_id = $1
+		`,
+		c.CurrentUser.ID,
+	)
+	if err != nil {
+		if errors.Is(err, db.ErrNoMatchingRows) {
+			// we're ok, just no user
+		} else {
+			return ErrorResponse(http.StatusInternalServerError, oops.New(err, "failed to fetch current user's Discord account"))
+		}
+	} else {
+		userDiscord = iUserDiscord.(*models.DiscordUser)
+	}
+
+	type templateData struct {
+		templates.BaseData
+		DiscordUser  *templates.DiscordUser
+		AuthorizeURL string
+	}
+
+	baseData := getBaseData(c)
+	baseData.Title = "Discord Test"
+
+	params := make(url.Values)
+	params.Set("response_type", "code")
+	params.Set("client_id", config.Config.Discord.OAuthClientID)
+	params.Set("scope", "identify")
+	params.Set("state", c.CurrentSession.CSRFToken)
+	params.Set("redirect_uri", hmnurl.BuildDiscordOAuthCallback())
+
+	td := templateData{
+		BaseData:     baseData,
+		AuthorizeURL: fmt.Sprintf("https://discord.com/api/oauth2/authorize?%s", params.Encode()),
+	}
+
+	if userDiscord != nil {
+		u := templates.DiscordUserToTemplate(userDiscord)
+		td.DiscordUser = &u
+	}
+
+	var res ResponseData
+	res.MustWriteTemplate("discordtest.html", td, c.Perf)
+	return res
+}
+
+func DiscordOAuthCallback(c *RequestContext) ResponseData {
+	query := c.Req.URL.Query()
+
+	// Check the state
+	state := query.Get("state")
+	if state != c.CurrentSession.CSRFToken {
+		// CSRF'd!!!!
+
+		// TODO(compression): Should this and the CSRF middleware be pulled out to
+		// a separate function?
+
+		c.Logger.Warn().Str("userId", c.CurrentUser.Username).Msg("user failed Discord OAuth state validation - potential attack?")
+
+		err := auth.DeleteSession(c.Context(), c.Conn, c.CurrentSession.ID)
+		if err != nil {
+			c.Logger.Error().Err(err).Msg("failed to delete session on Discord OAuth state failure")
+		}
+
+		res := c.Redirect("/", http.StatusSeeOther)
+		res.SetCookie(auth.DeleteSessionCookie)
+
+		return res
+	}
+
+	// Check for error values and redirect back to ????
+	if query.Get("error") != "" {
+		// TODO: actually handle these errors
+		return ErrorResponse(http.StatusBadRequest, errors.New(query.Get("error")))
+	}
+
+	// Do the actual token exchange and redirect back to ????
+	code := query.Get("code")
+	res, err := discord.ExchangeOAuthCode(c.Context(), code, hmnurl.BuildDiscordOAuthCallback()) // TODO: Redirect to the right place
+	if err != nil {
+		return ErrorResponse(http.StatusInternalServerError, oops.New(err, "failed to exchange Discord authorization code"))
+	}
+	expiry := time.Now().Add(time.Duration(res.ExpiresIn) * time.Second)
+
+	user, err := discord.GetCurrentUserAsOAuth(c.Context(), res.AccessToken)
+	if err != nil {
+		return ErrorResponse(http.StatusInternalServerError, oops.New(err, "failed to fetch Discord user info"))
+	}
+
+	// TODO: Add the role on Discord
+	err = discord.AddGuildMemberRole(c.Context(), user.ID, config.Config.Discord.MemberRoleID)
+	if err != nil {
+		return ErrorResponse(http.StatusInternalServerError, oops.New(err, "failed to add member role"))
+	}
+
+	_, err = c.Conn.Exec(c.Context(),
+		`
+		INSERT INTO handmade_discorduser (username, discriminator, access_token, refresh_token, avatar, locale, userid, expiry, hmn_user_id)
+		VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9)
+		`,
+		user.Username,
+		user.Discriminator,
+		res.AccessToken,
+		res.RefreshToken,
+		user.Avatar,
+		user.Locale,
+		user.ID,
+		expiry,
+		c.CurrentUser.ID,
+	)
+	if err != nil {
+		return ErrorResponse(http.StatusInternalServerError, oops.New(err, "failed to save new Discord user info"))
+	}
+
+	return c.Redirect(hmnurl.BuildDiscordTest(), http.StatusSeeOther)
+}

src/website/routes.go

@@ -197,6 +197,9 @@ func NewWebsiteRoutes(conn *pgxpool.Pool, perfCollector *perf.PerfCollector) htt
 	mainRoutes.GET(hmnurl.RegexPodcastEpisode, PodcastEpisode)
 	mainRoutes.GET(hmnurl.RegexPodcastRSS, PodcastRSS)
 
+	mainRoutes.GET(hmnurl.RegexDiscordTest, authMiddleware(DiscordTest)) // TODO: Delete this route
+	mainRoutes.GET(hmnurl.RegexDiscordOAuthCallback, authMiddleware(DiscordOAuthCallback))
+
 	mainRoutes.GET(hmnurl.RegexProjectCSS, ProjectCSS)
 	mainRoutes.GET(hmnurl.RegexEditorPreviewsJS, func(c *RequestContext) ResponseData {
 		var res ResponseData