1 files changed, 204 insertions, 0 deletions
diff --git a/internal/api/client/auth/authorize.go b/internal/api/client/auth/authorize.go
new file mode 100644
index 000000000..d5f8ee214
--- /dev/null
+++ b/internal/api/client/auth/authorize.go
@@ -0,0 +1,204 @@
+/*
+   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/http"
+	"net/url"
+
+	"github.com/gin-contrib/sessions"
+	"github.com/gin-gonic/gin"
+	"github.com/sirupsen/logrus"
+	"github.com/superseriousbusiness/gotosocial/internal/api/model"
+	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
+)
+
+// AuthorizeGETHandler should be served as GET at https://example.org/oauth/authorize
+// The idea here is to present an oauth authorize page to the user, with a button
+// that they have to click to accept. See here: https://docs.joinmastodon.org/methods/apps/oauth/#authorize-a-user
+func (m *Module) AuthorizeGETHandler(c *gin.Context) {
+	l := m.log.WithField("func", "AuthorizeGETHandler")
+	s := sessions.Default(c)
+
+	// UserID will be set in the session by AuthorizePOSTHandler if the caller has already gone through the authentication flow
+	// If it's not set, then we don't know yet who the user is, so we need to redirect them to the sign in page.
+	userID, ok := s.Get("userid").(string)
+	if !ok || userID == "" {
+		l.Trace("userid was empty, parsing form then redirecting to sign in page")
+		if err := parseAuthForm(c, l); err != nil {
+			c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
+		} else {
+			c.Redirect(http.StatusFound, AuthSignInPath)
+		}
+		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("client_id").(string)
+	if !ok || clientID == "" {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": "no client_id found in session"})
+		return
+	}
+	app := &gtsmodel.Application{
+		ClientID: clientID,
+	}
+	if err := m.db.GetWhere("client_id", app.ClientID, app); err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": fmt.Sprintf("no application found for client id %s", clientID)})
+		return
+	}
+
+	// we can also use the userid of the user to fetch their username from the db to greet them nicely <3
+	user := &gtsmodel.User{
+		ID: userID,
+	}
+	if err := m.db.GetByID(user.ID, user); err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
+		return
+	}
+
+	acct := &gtsmodel.Account{
+		ID: user.AccountID,
+	}
+
+	if err := m.db.GetByID(acct.ID, acct); err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
+		return
+	}
+
+	// Finally we should also get the redirect and scope of this particular request, as stored in the session.
+	redirect, ok := s.Get("redirect_uri").(string)
+	if !ok || redirect == "" {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": "no redirect_uri found in session"})
+		return
+	}
+	scope, ok := s.Get("scope").(string)
+	if !ok || scope == "" {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": "no scope found in session"})
+		return
+	}
+
+	// the authorize template will display a form to the user where they can get some information
+	// about the app that's trying to authorize, and the scope of the request.
+	// They can then approve it if it looks OK to them, which will POST to the AuthorizePOSTHandler
+	l.Trace("serving authorize html")
+	c.HTML(http.StatusOK, "authorize.tmpl", gin.H{
+		"appname":    app.Name,
+		"appwebsite": app.Website,
+		"redirect":   redirect,
+		"scope":      scope,
+		"user":       acct.Username,
+	})
+}
+
+// AuthorizePOSTHandler should be served as POST at https://example.org/oauth/authorize
+// At this point we assume that the user has A) logged in and B) accepted that the app should act for them,
+// so we should proceed with the authentication flow and generate an oauth token for them if we can.
+// See here: https://docs.joinmastodon.org/methods/apps/oauth/#authorize-a-user
+func (m *Module) AuthorizePOSTHandler(c *gin.Context) {
+	l := m.log.WithField("func", "AuthorizePOSTHandler")
+	s := sessions.Default(c)
+
+	// At this point we know the user has said 'yes' to allowing the application and oauth client
+	// work for them, so we can set the
+
+	// We need to retrieve the original form submitted to the authorizeGEThandler, and
+	// 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.
+	forceLogin, ok := s.Get("force_login").(string)
+	if !ok {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "session missing force_login"})
+		return
+	}
+	responseType, ok := s.Get("response_type").(string)
+	if !ok || responseType == "" {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "session missing response_type"})
+		return
+	}
+	clientID, ok := s.Get("client_id").(string)
+	if !ok || clientID == "" {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "session missing client_id"})
+		return
+	}
+	redirectURI, ok := s.Get("redirect_uri").(string)
+	if !ok || redirectURI == "" {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "session missing redirect_uri"})
+		return
+	}
+	scope, ok := s.Get("scope").(string)
+	if !ok {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "session missing scope"})
+		return
+	}
+	userID, ok := s.Get("userid").(string)
+	if !ok {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "session missing userid"})
+		return
+	}
+	// we're done with the session so we can clear it now
+	s.Clear()
+
+	// now set the values on the request
+	values := url.Values{}
+	values.Set("force_login", forceLogin)
+	values.Set("response_type", responseType)
+	values.Set("client_id", clientID)
+	values.Set("redirect_uri", redirectURI)
+	values.Set("scope", scope)
+	values.Set("userid", userID)
+	c.Request.Form = values
+	l.Tracef("values on request set to %+v", c.Request.Form)
+
+	// and proceed with authorization using the oauth2 library
+	if err := m.server.HandleAuthorizeRequest(c.Writer, c.Request); err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
+	}
+}
+
+// parseAuthForm parses the OAuthAuthorize form in the gin context, and stores
+// the values in the form into the session.
+func parseAuthForm(c *gin.Context, l *logrus.Entry) error {
+	s := sessions.Default(c)
+
+	// first make sure they've filled out the authorize form with the required values
+	form := &model.OAuthAuthorize{}
+	if err := c.ShouldBind(form); err != nil {
+		return err
+	}
+	l.Tracef("parsed form: %+v", form)
+
+	// these fields are *required* so check 'em
+	if form.ResponseType == "" || form.ClientID == "" || form.RedirectURI == "" {
+		return errors.New("missing one of: response_type, client_id or redirect_uri")
+	}
+
+	// set default scope to read
+	if form.Scope == "" {
+		form.Scope = "read"
+	}
+
+	// save these values from the form so we can use them elsewhere in the session
+	s.Set("force_login", form.ForceLogin)
+	s.Set("response_type", form.ResponseType)
+	s.Set("client_id", form.ClientID)
+	s.Set("redirect_uri", form.RedirectURI)
+	s.Set("scope", form.Scope)
+	return s.Save()
+}