Oidc (#109)

* add oidc config

* inching forward with oidc idp

* lil webfingy fix

* bit more progress

* further oidc

* oidc now working

* document dex config

* replace broken images

* add additional credits

* tiny doc update

* update

* add oidc config

* inching forward with oidc idp

* bit more progress

* further oidc

* oidc now working

* document dex config

* replace broken images

* add additional credits

* tiny doc update

* update

* document

* docs + comments

18 files changed, 715 insertions, 75 deletions

diff --git a/internal/api/client/auth/auth.go b/internal/api/client/auth/auth.go
index 7cddc3e74..bcc338ce0 100644
--- a/internal/api/client/auth/auth.go
+++ b/internal/api/client/auth/auth.go
@@ -26,6 +26,7 @@ import (
 	"github.com/superseriousbusiness/gotosocial/internal/config"
 	"github.com/superseriousbusiness/gotosocial/internal/db"
 	"github.com/superseriousbusiness/gotosocial/internal/oauth"
+	"github.com/superseriousbusiness/gotosocial/internal/oidc"
 	"github.com/superseriousbusiness/gotosocial/internal/router"
 )
 
@@ -36,40 +37,37 @@ const (
 	OauthTokenPath = "/oauth/token"
 	// OauthAuthorizePath is the API path for authorization requests (eg., authorize this app to act on my behalf as a user)
 	OauthAuthorizePath = "/oauth/authorize"
+	// CallbackPath is the API path for receiving callback tokens from external OIDC providers
+	CallbackPath = oidc.CallbackPath
+
+	callbackStateParam = "state"
+	callbackCodeParam  = "code"
 
 	sessionUserID       = "userid"
 	sessionClientID     = "client_id"
 	sessionRedirectURI  = "redirect_uri"
 	sessionForceLogin   = "force_login"
 	sessionResponseType = "response_type"
-	sessionCode         = "code"
 	sessionScope        = "scope"
+	sessionState        = "state"
 )
 
-var sessionKeys []string = []string{
-	sessionUserID,
-	sessionClientID,
-	sessionRedirectURI,
-	sessionForceLogin,
-	sessionResponseType,
-	sessionCode,
-	sessionScope,
-}
-
 // Module implements the ClientAPIModule interface for
 type Module struct {
 	config *config.Config
 	db     db.DB
 	server oauth.Server
+	idp    oidc.IDP
 	log    *logrus.Logger
 }
 
 // New returns a new auth module
-func New(config *config.Config, db db.DB, server oauth.Server, log *logrus.Logger) api.ClientModule {
+func New(config *config.Config, db db.DB, server oauth.Server, idp oidc.IDP, log *logrus.Logger) api.ClientModule {
 	return &Module{
 		config: config,
 		db:     db,
 		server: server,
+		idp:    idp,
 		log:    log,
 	}
 }
@@ -84,6 +82,8 @@ func (m *Module) Route(s router.Router) error {
 	s.AttachHandler(http.MethodGet, OauthAuthorizePath, m.AuthorizeGETHandler)
 	s.AttachHandler(http.MethodPost, OauthAuthorizePath, m.AuthorizePOSTHandler)
 
+	s.AttachHandler(http.MethodGet, CallbackPath, m.CallbackGETHandler)
+
 	s.AttachMiddleware(m.OauthTokenMiddleware)
 	return nil
 }
diff --git a/internal/api/client/auth/authorize.go b/internal/api/client/auth/authorize.go
index fb16b00fc..a10408723 100644
--- a/internal/api/client/auth/authorize.go
+++ b/internal/api/client/auth/authorize.go
@@ -23,9 +23,11 @@ import (
 	"fmt"
 	"net/http"
 	"net/url"
+	"strings"
 
 	"github.com/gin-contrib/sessions"
 	"github.com/gin-gonic/gin"
+	"github.com/google/uuid"
 	"github.com/superseriousbusiness/gotosocial/internal/api/model"
 	"github.com/superseriousbusiness/gotosocial/internal/db"
 	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
@@ -46,16 +48,19 @@ func (m *Module) AuthorizeGETHandler(c *gin.Context) {
 		form := &model.OAuthAuthorize{}
 		if err := c.Bind(form); err != nil {
 			l.Debugf("invalid auth form: %s", err)
+			m.clearSession(s)
+			c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
 			return
 		}
-		l.Tracef("parsed auth form: %+v", form)
+		l.Debugf("parsed auth form: %+v", form)
 
 		if err := extractAuthForm(s, form); err != nil {
 			l.Debugf(fmt.Sprintf("error parsing form at /oauth/authorize: %s", err))
+			m.clearSession(s)
 			c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
 			return
 		}
-		c.Redirect(http.StatusFound, AuthSignInPath)
+		c.Redirect(http.StatusSeeOther, AuthSignInPath)
 		return
 	}
 
@@ -69,6 +74,7 @@ func (m *Module) AuthorizeGETHandler(c *gin.Context) {
 		ClientID: clientID,
 	}
 	if err := m.db.GetWhere([]db.Where{{Key: sessionClientID, Value: app.ClientID}}, app); err != nil {
+		m.clearSession(s)
 		c.JSON(http.StatusInternalServerError, gin.H{"error": fmt.Sprintf("no application found for client id %s", clientID)})
 		return
 	}
@@ -78,6 +84,7 @@ func (m *Module) AuthorizeGETHandler(c *gin.Context) {
 		ID: userID,
 	}
 	if err := m.db.GetByID(user.ID, user); err != nil {
+		m.clearSession(s)
 		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
 		return
 	}
@@ -87,6 +94,7 @@ func (m *Module) AuthorizeGETHandler(c *gin.Context) {
 	}
 
 	if err := m.db.GetByID(acct.ID, acct); err != nil {
+		m.clearSession(s)
 		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
 		return
 	}
@@ -94,11 +102,13 @@ func (m *Module) AuthorizeGETHandler(c *gin.Context) {
 	// Finally we should also get the redirect and scope of this particular request, as stored in the session.
 	redirect, ok := s.Get(sessionRedirectURI).(string)
 	if !ok || redirect == "" {
+		m.clearSession(s)
 		c.JSON(http.StatusInternalServerError, gin.H{"error": "no redirect_uri found in session"})
 		return
 	}
 	scope, ok := s.Get(sessionScope).(string)
 	if !ok || scope == "" {
+		m.clearSession(s)
 		c.JSON(http.StatusInternalServerError, gin.H{"error": "no scope found in session"})
 		return
 	}
@@ -128,48 +138,42 @@ func (m *Module) AuthorizePOSTHandler(c *gin.Context) {
 	// recreate it on the request so that it can be used further by the oauth2 library.
 	// So first fetch all the values from the session.
 
+	errs := []string{}
+
 	forceLogin, ok := s.Get(sessionForceLogin).(string)
 	if !ok {
-		c.JSON(http.StatusBadRequest, gin.H{"error": "session missing force_login"})
-		return
+		forceLogin = "false"
 	}
 
 	responseType, ok := s.Get(sessionResponseType).(string)
 	if !ok || responseType == "" {
-		c.JSON(http.StatusBadRequest, gin.H{"error": "session missing response_type"})
-		return
+		errs = append(errs, "session missing response_type")
 	}
 
 	clientID, ok := s.Get(sessionClientID).(string)
 	if !ok || clientID == "" {
-		c.JSON(http.StatusBadRequest, gin.H{"error": "session missing client_id"})
-		return
+		errs = append(errs, "session missing client_id")
 	}
 
 	redirectURI, ok := s.Get(sessionRedirectURI).(string)
 	if !ok || redirectURI == "" {
-		c.JSON(http.StatusBadRequest, gin.H{"error": "session missing redirect_uri"})
-		return
+		errs = append(errs, "session missing redirect_uri")
 	}
 
 	scope, ok := s.Get(sessionScope).(string)
 	if !ok {
-		c.JSON(http.StatusBadRequest, gin.H{"error": "session missing scope"})
-		return
+		errs = append(errs, "session missing scope")
 	}
 
 	userID, ok := s.Get(sessionUserID).(string)
 	if !ok {
-		c.JSON(http.StatusBadRequest, gin.H{"error": "session missing userid"})
-		return
+		errs = append(errs, "session missing userid")
 	}
 
-	// we're done with the session so we can clear it now
-	for _, key := range sessionKeys {
-		s.Delete(key)
-	}
-	if err := s.Save(); err != nil {
-		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
+	m.clearSession(s)
+
+	if len(errs) != 0 {
+		c.JSON(http.StatusBadRequest, gin.H{"error": strings.Join(errs, ": ")})
 		return
 	}
 
@@ -209,5 +213,6 @@ func extractAuthForm(s sessions.Session, form *model.OAuthAuthorize) error {
 	s.Set(sessionClientID, form.ClientID)
 	s.Set(sessionRedirectURI, form.RedirectURI)
 	s.Set(sessionScope, form.Scope)
+	s.Set(sessionState, uuid.NewString())
 	return s.Save()
 }
diff --git a/internal/api/client/auth/callback.go b/internal/api/client/auth/callback.go
new file mode 100644
index 000000000..8bf2a50b5
--- /dev/null
+++ b/internal/api/client/auth/callback.go
@@ -0,0 +1,219 @@
+/*
+   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 auth
+
+import (
+	"errors"
+	"fmt"
+	"net"
+	"net/http"
+	"strconv"
+	"strings"
+
+	"github.com/gin-contrib/sessions"
+	"github.com/gin-gonic/gin"
+	"github.com/google/uuid"
+	"github.com/superseriousbusiness/gotosocial/internal/db"
+	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
+	"github.com/superseriousbusiness/gotosocial/internal/oidc"
+	"github.com/superseriousbusiness/gotosocial/internal/util"
+)
+
+// CallbackGETHandler parses a token from an external auth provider.
+func (m *Module) CallbackGETHandler(c *gin.Context) {
+	s := sessions.Default(c)
+
+	// first make sure the state set in the cookie is the same as the state returned from the external provider
+	state := c.Query(callbackStateParam)
+	if state == "" {
+		m.clearSession(s)
+		c.JSON(http.StatusForbidden, gin.H{"error": "state query not found on callback"})
+		return
+	}
+
+	savedStateI := s.Get(sessionState)
+	savedState, ok := savedStateI.(string)
+	if !ok {
+		m.clearSession(s)
+		c.JSON(http.StatusForbidden, gin.H{"error": "state not found in session"})
+		return
+	}
+
+	if state != savedState {
+		m.clearSession(s)
+		c.JSON(http.StatusForbidden, gin.H{"error": "state mismatch"})
+		return
+	}
+
+	code := c.Query(callbackCodeParam)
+
+	claims, err := m.idp.HandleCallback(c.Request.Context(), code)
+	if err != nil {
+		m.clearSession(s)
+		c.JSON(http.StatusForbidden, gin.H{"error": err.Error()})
+		return
+	}
+
+	// We can use the client_id on the session to retrieve info about the app associated with the client_id
+	clientID, ok := s.Get(sessionClientID).(string)
+	if !ok || clientID == "" {
+		m.clearSession(s)
+		c.JSON(http.StatusInternalServerError, gin.H{"error": "no client_id found in session during callback"})
+		return
+	}
+	app := &gtsmodel.Application{
+		ClientID: clientID,
+	}
+	if err := m.db.GetWhere([]db.Where{{Key: sessionClientID, Value: app.ClientID}}, app); err != nil {
+		m.clearSession(s)
+		c.JSON(http.StatusInternalServerError, gin.H{"error": fmt.Sprintf("no application found for client id %s", clientID)})
+		return
+	}
+
+	user, err := m.parseUserFromClaims(claims, net.IP(c.ClientIP()), app.ID)
+	if err != nil {
+		m.clearSession(s)
+		c.JSON(http.StatusForbidden, gin.H{"error": err.Error()})
+		return
+	}
+
+	s.Set(sessionUserID, user.ID)
+	if err := s.Save(); err != nil {
+		m.clearSession(s)
+		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
+		return
+	}
+
+	c.Redirect(http.StatusFound, OauthAuthorizePath)
+}
+
+func (m *Module) parseUserFromClaims(claims *oidc.Claims, ip net.IP, appID string) (*gtsmodel.User, error) {
+	if claims.Email == "" {
+		return nil, errors.New("no email returned in claims")
+	}
+
+	// see if we already have a user for this email address
+	user := &gtsmodel.User{}
+	err := m.db.GetWhere([]db.Where{{Key: "email", Value: claims.Email}}, user)
+	if err == nil {
+		// we do! so we can just return it
+		return user, nil
+	}
+
+	if _, ok := err.(db.ErrNoEntries); !ok {
+		// we have an actual error in the database
+		return nil, fmt.Errorf("error checking database for email %s: %s", claims.Email, err)
+	}
+
+	// maybe we have an unconfirmed user
+	err = m.db.GetWhere([]db.Where{{Key: "unconfirmed_email", Value: claims.Email}}, user)
+	if err == nil {
+		// user is unconfirmed so return an error
+		return nil, fmt.Errorf("user with email address %s is unconfirmed", claims.Email)
+	}
+
+	if _, ok := err.(db.ErrNoEntries); !ok {
+		// we have an actual error in the database
+		return nil, fmt.Errorf("error checking database for email %s: %s", claims.Email, err)
+	}
+
+	// we don't have a confirmed or unconfirmed user with the claimed email address
+	// however, because we trust the OIDC provider, we should now create a user + account with the provided claims
+
+	// check if the email address is available for use; if it's not there's nothing we can so
+	if err := m.db.IsEmailAvailable(claims.Email); err != nil {
+		return nil, fmt.Errorf("email %s not available: %s", claims.Email, err)
+	}
+
+	// now we need a username
+	var username string
+
+	// make sure claims.Name is defined since we'll be using that for the username
+	if claims.Name == "" {
+		return nil, errors.New("no name returned in claims")
+	}
+
+	// check if we can just use claims.Name as-is
+	err = util.ValidateUsername(claims.Name)
+	if err == nil {
+		// the name we have on the claims is already a valid username
+		username = claims.Name
+	} else {
+		// not a valid username so we have to fiddle with it to try to make it valid
+		// first trim leading and trailing whitespace
+		trimmed := strings.TrimSpace(claims.Name)
+		// underscore any spaces in the middle of the name
+		underscored := strings.ReplaceAll(trimmed, " ", "_")
+		// lowercase the whole thing
+		lower := strings.ToLower(underscored)
+		// see if this is valid....
+		if err := util.ValidateUsername(lower); err == nil {
+			// we managed to get a valid username
+			username = lower
+		} else {
+			return nil, fmt.Errorf("couldn't parse a valid username from claims.Name value of %s", claims.Name)
+		}
+	}
+
+	var iString string
+	var found bool
+	// if the username isn't available we need to iterate on it until we find one that is
+	// we should try to do this in a predictable way so we just keep iterating i by one and trying
+	// the username with that number on the end
+	//
+	// note that for the first iteration, iString is still "" when the check is made, so our first choice
+	// is still the raw username with no integer stuck on the end
+	for i := 1; !found; i = i + 1 {
+		if err := m.db.IsUsernameAvailable(username + iString); err != nil {
+			if strings.Contains(err.Error(), "db error") {
+				// if there's an actual db error we should return
+				return nil, fmt.Errorf("error checking username availability: %s", err)
+			}
+		} else {
+			// no error so we've found a username that works
+			found = true
+			username = username + iString
+			continue
+		}
+		iString = strconv.Itoa(i)
+	}
+
+	// check if the user is in any recognised admin groups
+	var admin bool
+	for _, g := range claims.Groups {
+		if strings.EqualFold(g, "admin") || strings.EqualFold(g, "admins") {
+			admin = true
+		}
+	}
+
+	// we still need to set *a* password even if it's not a password the user will end up using, so set something random
+	// in this case, we'll just set two uuids on top of each other, which should be long + random enough to baffle any attempts to crack.
+	//
+	// if the user ever wants to log in using gts password rather than oidc flow, they'll have to request a password reset, which is fine
+	password := uuid.NewString() + uuid.NewString()
+
+	// create the user! this will also create an account and store it in the database so we don't need to do that here
+	user, err = m.db.NewSignup(username, "", m.config.AccountsConfig.RequireApproval, claims.Email, password, ip, "", appID, claims.EmailVerified, admin)
+	if err != nil {
+		return nil, fmt.Errorf("error creating user: %s", err)
+	}
+
+	return user, nil
+
+}
diff --git a/internal/api/client/auth/signin.go b/internal/api/client/auth/signin.go
index 7974a8cfa..543505cbd 100644
--- a/internal/api/client/auth/signin.go
+++ b/internal/api/client/auth/signin.go
@@ -39,7 +39,24 @@ type login struct {
 // The idea is to present a sign in page to the user, where they can enter their username and password.
 // The form will then POST to the sign in page, which will be handled by SignInPOSTHandler
 func (m *Module) SignInGETHandler(c *gin.Context) {
-	m.log.WithField("func", "SignInGETHandler").Trace("serving sign in html")
+	l := m.log.WithField("func", "SignInGETHandler")
+	l.Trace("entering sign in handler")
+	if m.idp != nil {
+		s := sessions.Default(c)
+
+		stateI := s.Get(sessionState)
+		state, ok := stateI.(string)
+		if !ok {
+			m.clearSession(s)
+			c.JSON(http.StatusForbidden, gin.H{"error": "state not found in session"})
+			return
+		}
+
+		redirect := m.idp.AuthCodeURL(state)
+		l.Debugf("redirecting to external idp at %s", redirect)
+		c.Redirect(http.StatusSeeOther, redirect)
+		return
+	}
 	c.HTML(http.StatusOK, "sign-in.tmpl", gin.H{})
 }
 
@@ -52,6 +69,7 @@ func (m *Module) SignInPOSTHandler(c *gin.Context) {
 	form := &login{}
 	if err := c.ShouldBind(form); err != nil {
 		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
+		m.clearSession(s)
 		return
 	}
 	l.Tracef("parsed form: %+v", form)
@@ -59,12 +77,14 @@ func (m *Module) SignInPOSTHandler(c *gin.Context) {
 	userid, err := m.ValidatePassword(form.Email, form.Password)
 	if err != nil {
 		c.String(http.StatusForbidden, err.Error())
+		m.clearSession(s)
 		return
 	}
 
 	s.Set(sessionUserID, userid)
 	if err := s.Save(); err != nil {
 		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
+		m.clearSession(s)
 		return
 	}
 
diff --git a/internal/api/client/auth/util.go b/internal/api/client/auth/util.go
new file mode 100644
index 000000000..48fe4748a
--- /dev/null
+++ b/internal/api/client/auth/util.go
@@ -0,0 +1,17 @@
+package auth
+
+import (
+	"github.com/gin-contrib/sessions"
+)
+
+func (m *Module) clearSession(s sessions.Session) {
+	s.Clear()
+
+	// newOptions := router.SessionOptions(m.config)
+	// newOptions.MaxAge = -1 // instruct browser to delete cookie immediately
+	// s.Options(newOptions)
+
+	if err := s.Save(); err != nil {
+		panic(err)
+	}
+}
diff --git a/internal/cliactions/admin/account/account.go b/internal/cliactions/admin/account/account.go
index 3bb1afada..123913327 100644
--- a/internal/cliactions/admin/account/account.go
+++ b/internal/cliactions/admin/account/account.go
@@ -64,7 +64,7 @@ var Create cliactions.GTSAction = func(ctx context.Context, c *config.Config, lo
 		return err
 	}
 
-	_, err = dbConn.NewSignup(username, "", false, email, password, nil, "", "")
+	_, err = dbConn.NewSignup(username, "", false, email, password, nil, "", "", false, false)
 	if err != nil {
 		return err
 	}
diff --git a/internal/cliactions/server/server.go b/internal/cliactions/server/server.go
index 316be614e..3c4f97dea 100644
--- a/internal/cliactions/server/server.go
+++ b/internal/cliactions/server/server.go
@@ -42,6 +42,7 @@ import (
 	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
 	"github.com/superseriousbusiness/gotosocial/internal/media"
 	"github.com/superseriousbusiness/gotosocial/internal/oauth"
+	"github.com/superseriousbusiness/gotosocial/internal/oidc"
 	"github.com/superseriousbusiness/gotosocial/internal/processing"
 	"github.com/superseriousbusiness/gotosocial/internal/router"
 	timelineprocessing "github.com/superseriousbusiness/gotosocial/internal/timeline"
@@ -121,8 +122,13 @@ var Start cliactions.GTSAction = func(ctx context.Context, c *config.Config, log
 		return fmt.Errorf("error starting processor: %s", err)
 	}
 
+	idp, err := oidc.NewIDP(c, log)
+	if err != nil {
+		return fmt.Errorf("error creating oidc idp: %s", err)
+	}
+
 	// build client api modules
-	authModule := auth.New(c, dbService, oauthServer, log)
+	authModule := auth.New(c, dbService, oauthServer, idp, log)
 	accountModule := account.New(c, processor, log)
 	instanceModule := instance.New(c, processor, log)
 	appsModule := app.New(c, processor, log)
diff --git a/internal/cliactions/testrig/testrig.go b/internal/cliactions/testrig/testrig.go
index c669dd851..e2b97fe61 100644
--- a/internal/cliactions/testrig/testrig.go
+++ b/internal/cliactions/testrig/testrig.go
@@ -37,6 +37,7 @@ import (
 	"github.com/superseriousbusiness/gotosocial/internal/cliactions"
 	"github.com/superseriousbusiness/gotosocial/internal/config"
 	"github.com/superseriousbusiness/gotosocial/internal/gotosocial"
+	"github.com/superseriousbusiness/gotosocial/internal/oidc"
 	"github.com/superseriousbusiness/gotosocial/internal/web"
 	"github.com/superseriousbusiness/gotosocial/testrig"
 )
@@ -66,8 +67,13 @@ var Start cliactions.GTSAction = func(ctx context.Context, _ *config.Config, log
 		return fmt.Errorf("error starting processor: %s", err)
 	}
 
+	idp, err := oidc.NewIDP(c, log)
+	if err != nil {
+		return fmt.Errorf("error creating oidc idp: %s", err)
+	}
+
 	// build client api modules
-	authModule := auth.New(c, dbService, oauthServer, log)
+	authModule := auth.New(c, dbService, oauthServer, idp, log)
 	accountModule := account.New(c, processor, log)
 	instanceModule := instance.New(c, processor, log)
 	appsModule := app.New(c, processor, log)
diff --git a/internal/config/config.go b/internal/config/config.go
index e2bfd0b68..117b8efb5 100644
--- a/internal/config/config.go
+++ b/internal/config/config.go
@@ -57,6 +57,7 @@ type Config struct {
 	StorageConfig     *StorageConfig     `yaml:"storage"`
 	StatusesConfig    *StatusesConfig    `yaml:"statuses"`
 	LetsEncryptConfig *LetsEncryptConfig `yaml:"letsEncrypt"`
+	OIDCConfig        *OIDCConfig        `yaml:"oidc"`
 
 	/*
 		Not parsed from .yaml configuration file.
@@ -87,6 +88,7 @@ func Empty() *Config {
 		StorageConfig:     &StorageConfig{},
 		StatusesConfig:    &StatusesConfig{},
 		LetsEncryptConfig: &LetsEncryptConfig{},
+		OIDCConfig:        &OIDCConfig{},
 		AccountCLIFlags:   make(map[string]string),
 	}
 }
@@ -268,7 +270,34 @@ func (c *Config) ParseCLIFlags(f KeyedFlags, version string) error {
 		c.LetsEncryptConfig.EmailAddress = f.String(fn.LetsEncryptEmailAddress)
 	}
 
-	c.SoftwareVersion = GetDefaults().SoftwareVersion
+	// OIDC flags
+	if f.IsSet(fn.OIDCEnabled) {
+		c.OIDCConfig.Enabled = f.Bool(fn.OIDCEnabled)
+	}
+
+	if c.OIDCConfig.IDPName == "" || f.IsSet(fn.OIDCIdpName) {
+		c.OIDCConfig.IDPName = f.String(fn.OIDCIdpName)
+	}
+
+	if f.IsSet(fn.OIDCSkipVerification) {
+		c.OIDCConfig.SkipVerification = f.Bool(fn.OIDCSkipVerification)
+	}
+
+	if c.OIDCConfig.Issuer == "" || f.IsSet(fn.OIDCIssuer) {
+		c.OIDCConfig.Issuer = f.String(fn.OIDCIssuer)
+	}
+
+	if c.OIDCConfig.ClientID == "" || f.IsSet(fn.OIDCClientID) {
+		c.OIDCConfig.ClientID = f.String(fn.OIDCClientID)
+	}
+
+	if c.OIDCConfig.ClientSecret == "" || f.IsSet(fn.OIDCClientSecret) {
+		c.OIDCConfig.ClientSecret = f.String(fn.OIDCClientSecret)
+	}
+
+	if len(c.OIDCConfig.Scopes) == 0 || f.IsSet(fn.OIDCScopes) {
+		c.OIDCConfig.Scopes = f.StringSlice(fn.OIDCScopes)
+	}
 
 	// command-specific flags
 
@@ -278,7 +307,6 @@ func (c *Config) ParseCLIFlags(f KeyedFlags, version string) error {
 	c.AccountCLIFlags[PasswordFlag] = f.String(PasswordFlag)
 
 	c.SoftwareVersion = version
-
 	return nil
 }
 
@@ -287,6 +315,7 @@ func (c *Config) ParseCLIFlags(f KeyedFlags, version string) error {
 type KeyedFlags interface {
 	Bool(k string) bool
 	String(k string) string
+	StringSlice(k string) []string
 	Int(k string) int
 	IsSet(k string) bool
 }
@@ -337,6 +366,14 @@ type Flags struct {
 	LetsEncryptEnabled      string
 	LetsEncryptCertDir      string
 	LetsEncryptEmailAddress string
+
+	OIDCEnabled          string
+	OIDCIdpName          string
+	OIDCSkipVerification string
+	OIDCIssuer           string
+	OIDCClientID         string
+	OIDCClientSecret     string
+	OIDCScopes           string
 }
 
 // Defaults contains all the default values for a gotosocial config
@@ -385,6 +422,14 @@ type Defaults struct {
 	LetsEncryptEnabled      bool
 	LetsEncryptCertDir      string
 	LetsEncryptEmailAddress string
+
+	OIDCEnabled          bool
+	OIDCIdpName          string
+	OIDCSkipVerification bool
+	OIDCIssuer           string
+	OIDCClientID         string
+	OIDCClientSecret     string
+	OIDCScopes           []string
 }
 
 // GetFlagNames returns a struct containing the names of the various flags used for
@@ -434,6 +479,14 @@ func GetFlagNames() Flags {
 		LetsEncryptEnabled:      "letsencrypt-enabled",
 		LetsEncryptCertDir:      "letsencrypt-cert-dir",
 		LetsEncryptEmailAddress: "letsencrypt-email",
+
+		OIDCEnabled:          "oidc-enabled",
+		OIDCIdpName:          "oidc-idp-name",
+		OIDCSkipVerification: "oidc-skip-verification",
+		OIDCIssuer:           "oidc-issuer",
+		OIDCClientID:         "oidc-client-id",
+		OIDCClientSecret:     "oidc-client-secret",
+		OIDCScopes:           "oidc-scopes",
 	}
 }
 
@@ -484,5 +537,13 @@ func GetEnvNames() Flags {
 		LetsEncryptEnabled:      "GTS_LETSENCRYPT_ENABLED",
 		LetsEncryptCertDir:      "GTS_LETSENCRYPT_CERT_DIR",
 		LetsEncryptEmailAddress: "GTS_LETSENCRYPT_EMAIL",
+
+		OIDCEnabled:          "GTS_OIDC_ENABLED",
+		OIDCIdpName:          "GTS_OIDC_IDP_NAME",
+		OIDCSkipVerification: "GTS_OIDC_SKIP_VERIFICATION",
+		OIDCIssuer:           "GTS_OIDC_ISSUER",
+		OIDCClientID:         "GTS_OIDC_CLIENT_ID",
+		OIDCClientSecret:     "GTS_OIDC_CLIENT_SECRET",
+		OIDCScopes:           "GTS_OIDC_SCOPES",
 	}
 }
diff --git a/internal/config/default.go b/internal/config/default.go
index 099eead1c..61940eff4 100644
--- a/internal/config/default.go
+++ b/internal/config/default.go
@@ -1,5 +1,7 @@
 package config
 
+import "github.com/coreos/go-oidc/v3/oidc"
+
 // TestDefault returns a default config for testing
 func TestDefault() *Config {
 	defaults := GetTestDefaults()
@@ -52,6 +54,15 @@ func TestDefault() *Config {
 			CertDir:      defaults.LetsEncryptCertDir,
 			EmailAddress: defaults.LetsEncryptEmailAddress,
 		},
+		OIDCConfig: &OIDCConfig{
+			Enabled:          defaults.OIDCEnabled,
+			IDPName:          defaults.OIDCIdpName,
+			SkipVerification: defaults.OIDCSkipVerification,
+			Issuer:           defaults.OIDCIssuer,
+			ClientID:         defaults.OIDCClientID,
+			ClientSecret:     defaults.OIDCClientSecret,
+			Scopes:           defaults.OIDCScopes,
+		},
 	}
 }
 
@@ -107,6 +118,15 @@ func Default() *Config {
 			CertDir:      defaults.LetsEncryptCertDir,
 			EmailAddress: defaults.LetsEncryptEmailAddress,
 		},
+		OIDCConfig: &OIDCConfig{
+			Enabled:          defaults.OIDCEnabled,
+			IDPName:          defaults.OIDCIdpName,
+			SkipVerification: defaults.OIDCSkipVerification,
+			Issuer:           defaults.OIDCIssuer,
+			ClientID:         defaults.OIDCClientID,
+			ClientSecret:     defaults.OIDCClientSecret,
+			Scopes:           defaults.OIDCScopes,
+		},
 	}
 }
 
@@ -157,6 +177,14 @@ func GetDefaults() Defaults {
 		LetsEncryptEnabled:      true,
 		LetsEncryptCertDir:      "/gotosocial/storage/certs",
 		LetsEncryptEmailAddress: "",
+
+		OIDCEnabled:          false,
+		OIDCIdpName:          "",
+		OIDCSkipVerification: false,
+		OIDCIssuer:           "",
+		OIDCClientID:         "",
+		OIDCClientSecret:     "",
+		OIDCScopes:           []string{oidc.ScopeOpenID, "profile", "email", "groups"},
 	}
 }
 
@@ -204,5 +232,13 @@ func GetTestDefaults() Defaults {
 		LetsEncryptEnabled:      false,
 		LetsEncryptCertDir:      "",
 		LetsEncryptEmailAddress: "",
+
+		OIDCEnabled:          false,
+		OIDCIdpName:          "",
+		OIDCSkipVerification: false,
+		OIDCIssuer:           "",
+		OIDCClientID:         "",
+		OIDCClientSecret:     "",
+		OIDCScopes:           []string{oidc.ScopeOpenID, "profile", "email", "groups"},
 	}
 }
diff --git a/internal/config/oidc.go b/internal/config/oidc.go
new file mode 100644
index 000000000..06158bbb7
--- /dev/null
+++ b/internal/config/oidc.go
@@ -0,0 +1,30 @@
+/*
+   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 config
+
+// OIDCConfig contains configuration values for openID connect (oauth) authorization by an external service such as Dex.
+type OIDCConfig struct {
+	Enabled          bool     `yaml:"enabled"`
+	IDPName          string   `yaml:"idpName"`
+	SkipVerification bool     `yaml:"skipVerification"`
+	Issuer           string   `yaml:"issuer"`
+	ClientID         string   `yaml:"clientID"`
+	ClientSecret     string   `yaml:"clientSecret"`
+	Scopes           []string `yaml:"scopes"`
+}
diff --git a/internal/db/db.go b/internal/db/db.go
index bbe780e80..c764cc716 100644
--- a/internal/db/db.go
+++ b/internal/db/db.go
@@ -177,9 +177,9 @@ type DB interface {
 	// C) something went wrong in the db
 	IsEmailAvailable(email string) error
 
-	// NewSignup creates a new user in the database with the given parameters, with an *unconfirmed* email address.
+	// NewSignup creates a new user in the database with the given parameters.
 	// By the time this function is called, it should be assumed that all the parameters have passed validation!
-	NewSignup(username string, reason string, requireApproval bool, email string, password string, signUpIP net.IP, locale string, appID string) (*gtsmodel.User, error)
+	NewSignup(username string, reason string, requireApproval bool, email string, password string, signUpIP net.IP, locale string, appID string, emailVerified bool, admin bool) (*gtsmodel.User, error)
 
 	// SetHeaderOrAvatarForAccountID sets the header or avatar for the given accountID to the given media attachment.
 	SetHeaderOrAvatarForAccountID(mediaAttachment *gtsmodel.MediaAttachment, accountID string) error
diff --git a/internal/db/pg/pg.go b/internal/db/pg/pg.go
index 31312b61e..d49c50114 100644
--- a/internal/db/pg/pg.go
+++ b/internal/db/pg/pg.go
@@ -548,38 +548,49 @@ func (ps *postgresService) IsEmailAvailable(email string) error {
 	return nil
 }
 
-func (ps *postgresService) NewSignup(username string, reason string, requireApproval bool, email string, password string, signUpIP net.IP, locale string, appID string) (*gtsmodel.User, error) {
+func (ps *postgresService) NewSignup(username string, reason string, requireApproval bool, email string, password string, signUpIP net.IP, locale string, appID string, emailVerified bool, admin bool) (*gtsmodel.User, error) {
 	key, err := rsa.GenerateKey(rand.Reader, 2048)
 	if err != nil {
 		ps.log.Errorf("error creating new rsa key: %s", err)
 		return nil, err
 	}
 
-	newAccountURIs := util.GenerateURIsForAccount(username, ps.config.Protocol, ps.config.Host)
-	newAccountID, err := id.NewRandomULID()
+	// if something went wrong while creating a user, we might already have an account, so check here first...
+	a := &gtsmodel.Account{}
+	err = ps.conn.Model(a).Where("username = ?", username).Where("? IS NULL", pg.Ident("domain")).Select()
 	if err != nil {
-		return nil, err
-	}
+		// there's been an actual error
+		if err != pg.ErrNoRows {
+			return nil, fmt.Errorf("db error checking existence of account: %s", err)
+		}
 
-	a := &gtsmodel.Account{
-		ID:                    newAccountID,
-		Username:              username,
-		DisplayName:           username,
-		Reason:                reason,
-		URL:                   newAccountURIs.UserURL,
-		PrivateKey:            key,
-		PublicKey:             &key.PublicKey,
-		PublicKeyURI:          newAccountURIs.PublicKeyURI,
-		ActorType:             gtsmodel.ActivityStreamsPerson,
-		URI:                   newAccountURIs.UserURI,
-		InboxURI:              newAccountURIs.InboxURI,
-		OutboxURI:             newAccountURIs.OutboxURI,
-		FollowersURI:          newAccountURIs.FollowersURI,
-		FollowingURI:          newAccountURIs.FollowingURI,
-		FeaturedCollectionURI: newAccountURIs.CollectionURI,
-	}
-	if _, err = ps.conn.Model(a).Insert(); err != nil {
-		return nil, err
+		// we just don't have an account yet create one
+		newAccountURIs := util.GenerateURIsForAccount(username, ps.config.Protocol, ps.config.Host)
+		newAccountID, err := id.NewRandomULID()
+		if err != nil {
+			return nil, err
+		}
+
+		a = &gtsmodel.Account{
+			ID:                    newAccountID,
+			Username:              username,
+			DisplayName:           username,
+			Reason:                reason,
+			URL:                   newAccountURIs.UserURL,
+			PrivateKey:            key,
+			PublicKey:             &key.PublicKey,
+			PublicKeyURI:          newAccountURIs.PublicKeyURI,
+			ActorType:             gtsmodel.ActivityStreamsPerson,
+			URI:                   newAccountURIs.UserURI,
+			InboxURI:              newAccountURIs.InboxURI,
+			OutboxURI:             newAccountURIs.OutboxURI,
+			FollowersURI:          newAccountURIs.FollowersURI,
+			FollowingURI:          newAccountURIs.FollowingURI,
+			FeaturedCollectionURI: newAccountURIs.CollectionURI,
+		}
+		if _, err = ps.conn.Model(a).Insert(); err != nil {
+			return nil, err
+		}
 	}
 
 	pw, err := bcrypt.GenerateFromPassword([]byte(password), bcrypt.DefaultCost)
@@ -594,14 +605,25 @@ func (ps *postgresService) NewSignup(username string, reason string, requireAppr
 
 	u := &gtsmodel.User{
 		ID:                     newUserID,
-		AccountID:              newAccountID,
+		AccountID:              a.ID,
 		EncryptedPassword:      string(pw),
-		SignUpIP:               signUpIP,
+		SignUpIP:               signUpIP.To4(),
 		Locale:                 locale,
 		UnconfirmedEmail:       email,
 		CreatedByApplicationID: appID,
 		Approved:               !requireApproval, // if we don't require moderator approval, just pre-approve the user
 	}
+
+	if emailVerified {
+		u.ConfirmedAt = time.Now()
+		u.Email = email
+	}
+
+	if admin {
+		u.Admin = true
+		u.Moderator = true
+	}
+
 	if _, err = ps.conn.Model(u).Insert(); err != nil {
 		return nil, err
 	}
diff --git a/internal/oidc/claims.go b/internal/oidc/claims.go
new file mode 100644
index 000000000..b58c4662b
--- /dev/null
+++ b/internal/oidc/claims.go
@@ -0,0 +1,27 @@
+/*
+   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
+
+// Claims represents claims as found in an id_token returned from an OIDC flow.
+type Claims struct {
+	Email         string   `json:"email"`
+	EmailVerified bool     `json:"email_verified"`
+	Groups        []string `json:"groups"`
+	Name          string   `json:"name"`
+}
diff --git a/internal/oidc/handlecallback.go b/internal/oidc/handlecallback.go
new file mode 100644
index 000000000..2fbdc9309
--- /dev/null
+++ b/internal/oidc/handlecallback.go
@@ -0,0 +1,65 @@
+/*
+   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"
+	"errors"
+	"fmt"
+)
+
+func (i *idp) HandleCallback(ctx context.Context, code string) (*Claims, error) {
+	l := i.log.WithField("func", "HandleCallback")
+	if code == "" {
+		return nil, errors.New("code was empty string")
+	}
+
+	l.Debug("exchanging code for oauth2token")
+	oauth2Token, err := i.oauth2Config.Exchange(ctx, code)
+	if err != nil {
+		return nil, fmt.Errorf("error exchanging code for oauth2token: %s", err)
+	}
+
+	l.Debug("extracting id_token")
+	rawIDToken, ok := oauth2Token.Extra("id_token").(string)
+	if !ok {
+		return nil, errors.New("no id_token in oauth2token")
+	}
+	l.Debugf("raw id token: %s", rawIDToken)
+
+	// Parse and verify ID Token payload.
+	l.Debug("verifying id_token")
+	idTokenVerifier := i.provider.Verifier(i.oidcConf)
+	idToken, err := idTokenVerifier.Verify(ctx, rawIDToken)
+	if err != nil {
+		return nil, fmt.Errorf("could not verify id token: %s", err)
+	}
+
+	l.Debug("extracting claims from id_token")
+	claims := &Claims{}
+	if err := idToken.Claims(claims); err != nil {
+		return nil, fmt.Errorf("could not parse claims from idToken: %s", err)
+	}
+
+	return claims, nil
+}
+
+func (i *idp) AuthCodeURL(state string) string {
+	return i.oauth2Config.AuthCodeURL(state)
+}
diff --git a/internal/oidc/idp.go b/internal/oidc/idp.go
new file mode 100644
index 000000000..8758f6aad
--- /dev/null
+++ b/internal/oidc/idp.go
@@ -0,0 +1,121 @@
+/*
+   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/sirupsen/logrus"
+	"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
+	log          *logrus.Logger
+}
+
+// NewIDP returns a new IDP configured with the given config and logger.
+// 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(config *config.Config, log *logrus.Logger) (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(context.Background(), 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,
+		log:          log,
+	}, nil
+}
diff --git a/internal/processing/account/create.go b/internal/processing/account/create.go
index 8b29f147f..58ac0e43c 100644
--- a/internal/processing/account/create.go
+++ b/internal/processing/account/create.go
@@ -45,7 +45,7 @@ func (p *processor) Create(applicationToken oauth2.TokenInfo, application *gtsmo
 	}
 
 	l.Trace("creating new username and account")
-	user, err := p.db.NewSignup(form.Username, util.RemoveHTML(reason), p.config.AccountsConfig.RequireApproval, form.Email, form.Password, form.IP, form.Locale, application.ID)
+	user, err := p.db.NewSignup(form.Username, util.RemoveHTML(reason), p.config.AccountsConfig.RequireApproval, form.Email, form.Password, form.IP, form.Locale, application.ID, false, false)
 	if err != nil {
 		return nil, fmt.Errorf("error creating new signup in the database: %s", err)
 	}
diff --git a/internal/router/session.go b/internal/router/session.go
index 2d00f7677..2b9be2f56 100644
--- a/internal/router/session.go
+++ b/internal/router/session.go
@@ -33,6 +33,18 @@ import (
 	"github.com/superseriousbusiness/gotosocial/internal/id"
 )
 
+// SessionOptions returns the standard set of options to use for each session.
+func SessionOptions(cfg *config.Config) sessions.Options {
+	return sessions.Options{
+		Path:     "/",
+		Domain:   cfg.Host,
+		MaxAge:   120,                      // 2 minutes
+		Secure:   true,                     // only use cookie over https
+		HttpOnly: true,                     // exclude javascript from inspecting cookie
+		SameSite: http.SameSiteDefaultMode, // https://datatracker.ietf.org/doc/html/draft-ietf-httpbis-cookie-same-site-00#section-4.1.1
+	}
+}
+
 func useSession(cfg *config.Config, dbService db.DB, engine *gin.Engine) error {
 	// check if we have a saved router session already
 	routerSessions := []*gtsmodel.RouterSession{}
@@ -64,14 +76,7 @@ func useSession(cfg *config.Config, dbService db.DB, engine *gin.Engine) error {
 	}
 
 	store := memstore.NewStore(rs.Auth, rs.Crypt)
-	store.Options(sessions.Options{
-		Path:     "/",
-		Domain:   cfg.Host,
-		MaxAge:   120,                     // 2 minutes
-		Secure:   true,                    // only use cookie over https
-		HttpOnly: true,                    // exclude javascript from inspecting cookie
-		SameSite: http.SameSiteStrictMode, // https://datatracker.ietf.org/doc/html/draft-ietf-httpbis-cookie-same-site-00#section-4.1.1
-	})
+	store.Options(SessionOptions(cfg))
 	sessionName := fmt.Sprintf("gotosocial-%s", cfg.Host)
 	engine.Use(sessions.Sessions(sessionName, store))
 	return nil