gotosocial/internal/api/client/auth/callback.go

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/*
GoToSocial
2021-12-20 17:42:19 +00:00
Copyright (C) 2021-2022 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 (
"context"
"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/api"
"github.com/superseriousbusiness/gotosocial/internal/db"
"github.com/superseriousbusiness/gotosocial/internal/gtserror"
"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
"github.com/superseriousbusiness/gotosocial/internal/oidc"
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"github.com/superseriousbusiness/gotosocial/internal/validate"
)
// CallbackGETHandler parses a token from an external auth provider.
func (m *Module) CallbackGETHandler(c *gin.Context) {
s := sessions.Default(c)
// check the query vs session state parameter to mitigate csrf
// https://auth0.com/docs/secure/attack-protection/state-parameters
returnedInternalState := c.Query(callbackStateParam)
if returnedInternalState == "" {
m.clearSession(s)
err := fmt.Errorf("%s parameter not found on callback query", callbackStateParam)
api.ErrorHandler(c, gtserror.NewErrorBadRequest(err, err.Error()), m.processor.InstanceGet)
return
}
savedInternalStateI := s.Get(sessionInternalState)
savedInternalState, ok := savedInternalStateI.(string)
if !ok {
m.clearSession(s)
err := fmt.Errorf("key %s was not found in session", sessionInternalState)
api.ErrorHandler(c, gtserror.NewErrorBadRequest(err, err.Error()), m.processor.InstanceGet)
return
}
if returnedInternalState != savedInternalState {
m.clearSession(s)
err := errors.New("mismatch between callback state and saved state")
api.ErrorHandler(c, gtserror.NewErrorUnauthorized(err, err.Error()), m.processor.InstanceGet)
return
}
// retrieve stored claims using code
code := c.Query(callbackCodeParam)
if code == "" {
m.clearSession(s)
err := fmt.Errorf("%s parameter not found on callback query", callbackCodeParam)
api.ErrorHandler(c, gtserror.NewErrorBadRequest(err, err.Error()), m.processor.InstanceGet)
return
}
claims, errWithCode := m.idp.HandleCallback(c.Request.Context(), code)
if errWithCode != nil {
m.clearSession(s)
api.ErrorHandler(c, errWithCode, m.processor.InstanceGet)
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)
err := fmt.Errorf("key %s was not found in session", sessionClientID)
api.ErrorHandler(c, gtserror.NewErrorBadRequest(err, helpfulAdvice), m.processor.InstanceGet)
return
}
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app := &gtsmodel.Application{}
if err := m.db.GetWhere(c.Request.Context(), []db.Where{{Key: sessionClientID, Value: clientID}}, app); err != nil {
m.clearSession(s)
safe := fmt.Sprintf("application for %s %s could not be retrieved", sessionClientID, clientID)
var errWithCode gtserror.WithCode
if err == db.ErrNoEntries {
errWithCode = gtserror.NewErrorBadRequest(err, safe, helpfulAdvice)
} else {
errWithCode = gtserror.NewErrorInternalError(err, safe, helpfulAdvice)
}
api.ErrorHandler(c, errWithCode, m.processor.InstanceGet)
return
}
user, errWithCode := m.parseUserFromClaims(c.Request.Context(), claims, net.IP(c.ClientIP()), app.ID)
if errWithCode != nil {
m.clearSession(s)
api.ErrorHandler(c, errWithCode, m.processor.InstanceGet)
return
}
s.Set(sessionUserID, user.ID)
if err := s.Save(); err != nil {
m.clearSession(s)
api.ErrorHandler(c, gtserror.NewErrorInternalError(err), m.processor.InstanceGet)
return
}
c.Redirect(http.StatusFound, OauthAuthorizePath)
}
func (m *Module) parseUserFromClaims(ctx context.Context, claims *oidc.Claims, ip net.IP, appID string) (*gtsmodel.User, gtserror.WithCode) {
if claims.Email == "" {
err := errors.New("no email returned in claims")
return nil, gtserror.NewErrorBadRequest(err, err.Error())
}
// see if we already have a user for this email address
// if so, we don't need to continue + create one
user := &gtsmodel.User{}
err := m.db.GetWhere(ctx, []db.Where{{Key: "email", Value: claims.Email}}, user)
if err == nil {
return user, nil
}
if err != db.ErrNoEntries {
err := fmt.Errorf("error checking database for email %s: %s", claims.Email, err)
return nil, gtserror.NewErrorInternalError(err)
}
// maybe we have an unconfirmed user
err = m.db.GetWhere(ctx, []db.Where{{Key: "unconfirmed_email", Value: claims.Email}}, user)
if err == nil {
err := fmt.Errorf("user with email address %s is unconfirmed", claims.Email)
return nil, gtserror.NewErrorForbidden(err, err.Error())
}
if err != db.ErrNoEntries {
err := fmt.Errorf("error checking database for email %s: %s", claims.Email, err)
return nil, gtserror.NewErrorInternalError(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
emailAvailable, err := m.db.IsEmailAvailable(ctx, claims.Email)
if err != nil {
return nil, gtserror.NewErrorBadRequest(err)
}
if !emailAvailable {
return nil, gtserror.NewErrorConflict(fmt.Errorf("email address %s is not available", claims.Email))
}
// 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 == "" {
err := errors.New("no name returned in claims")
return nil, gtserror.NewErrorBadRequest(err, err.Error())
}
// check if we can just use claims.Name as-is
if err = validate.Username(claims.Name); 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 := validate.Username(lower); err != nil {
err := fmt.Errorf("couldn't parse a valid username from claims.Name value of %s: %s", claims.Name, err)
return nil, gtserror.NewErrorBadRequest(err, err.Error())
}
// we managed to get a valid username
username = lower
}
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++ {
usernameAvailable, err := m.db.IsUsernameAvailable(ctx, username+iString)
if err != nil {
return nil, gtserror.NewErrorInternalError(err)
}
if usernameAvailable {
// no error so we've found a username that works
found = true
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.
// 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()
// Since this user is created via oidc, which has been set up by the admin, we can assume that the account is already
// implicitly approved, and that the email address has already been verified: otherwise, we end up in situations where
// the admin first approves the user in OIDC, and then has to approve them again in GoToSocial, which doesn't make sense.
//
// In other words, if a user logs in via OIDC, they should be able to use their account straight away.
//
// See: https://github.com/superseriousbusiness/gotosocial/issues/357
requireApproval := false
emailVerified := true
// 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(ctx, username, "", requireApproval, claims.Email, password, ip, "", appID, emailVerified, admin)
if err != nil {
return nil, gtserror.NewErrorInternalError(err)
}
return user, nil
}