gotosocial/internal/api/client/auth/callback.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 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/db"
"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)
// 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
}
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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)
c.JSON(http.StatusInternalServerError, gin.H{"error": fmt.Sprintf("no application found for client id %s", clientID)})
return
}
user, err := m.parseUserFromClaims(c.Request.Context(), 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(ctx context.Context, 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(ctx, []db.Where{{Key: "email", Value: claims.Email}}, user)
if err == nil {
// we do! so we can just return it
return user, nil
}
if err != db.ErrNoEntries {
// 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(ctx, []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 err != db.ErrNoEntries {
// 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
emailAvailable, err := m.db.IsEmailAvailable(ctx, claims.Email)
if err != nil {
return nil, fmt.Errorf("email %s not available: %s", claims.Email, err)
}
if !emailAvailable {
return nil, fmt.Errorf("email %s in use", 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 == "" {
return nil, errors.New("no name returned in claims")
}
// check if we can just use claims.Name as-is
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err = validate.Username(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....
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if err := validate.Username(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++ {
usernameAvailable, err := m.db.IsUsernameAvailable(ctx, username+iString)
if err != nil {
return nil, 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
// 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(ctx, 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
}