Add gothic example code to internal/auth

internal/auth/auth.go

@@ -1,12 +1,16 @@
 package auth
 
 import (
+	"errors"
+	"log"
+	"net/http"
+	"net/url"
+	"os"
+
 	"github.com/gorilla/sessions"
 	"github.com/markbates/goth"
 	"github.com/markbates/goth/gothic"
 	"github.com/markbates/goth/providers/openidConnect"
-	"log"
-	"os"
 )
 
 func NewAuth(sessionStore *sessions.Store) {
@@ -24,6 +28,83 @@ func NewAuth(sessionStore *sessions.Store) {
 	if sessionStore != nil {
 		gothic.Store = *sessionStore
 	} else {
-    log.Println("No auth session store set. Falling back to default gothic setting.")
+		log.Println("No auth session store set. Falling back to default gothic setting.")
-  }
+	}
+}
+
+func CompleteAuthFlow(res http.ResponseWriter, req *http.Request) (goth.User, error) {
+	providerName, err := gothic.GetProviderName(req)
+	if err != nil {
+		log.Println("Error getting provider name: ", err)
+		return goth.User{}, err
+	}
+
+	provider, err := goth.GetProvider(providerName)
+	if err != nil {
+		return goth.User{}, err
+	}
+
+	value, err := gothic.GetFromSession(providerName, req)
+	if err != nil {
+		return goth.User{}, err
+	}
+	defer Logout(res, req)
+	sess, err := provider.UnmarshalSession(value)
+	if err != nil {
+		return goth.User{}, err
+	}
+
+	err = validateState(req, sess)
+	if err != nil {
+		return goth.User{}, err
+	}
+
+	user, err := provider.FetchUser(sess)
+	if err == nil {
+
+		return user, err
+	}
+
+	params := req.URL.Query()
+	if params.Encode() == "" && req.Method == "POST" {
+		req.ParseForm()
+		params = req.Form
+	}
+
+	_, err = sess.Authorize(provider, params)
+	if err != nil {
+		return goth.User{}, err
+	}
+
+	err = gothic.StoreInSession(providerName, sess.Marshal(), req, res)
+	if err != nil {
+		return goth.User{}, err
+	}
+
+	gu, err := provider.FetchUser(sess)
+	return gu, err
+}
+
+func Logout(res http.ResponseWriter, req *http.Request) error {
+	return gothic.Logout(res, req)
+}
+
+func validateState(req *http.Request, sess goth.Session) error {
+	rawAuthURL, err := sess.GetAuthURL()
+	if err != nil {
+		return err
+	}
+
+	authURL, err := url.Parse(rawAuthURL)
+	if err != nil {
+		return err
+	}
+
+	reqState := gothic.GetState(req)
+
+	originalState := authURL.Query().Get("state")
+	if originalState != "" && (originalState != reqState) {
+		return errors.New("state token mismatch")
+	}
+	return nil
 }

internal/server/routes.go

@@ -1,6 +1,7 @@
 package server
 
 import (
+	"gothtest/internal/auth"
 	"encoding/json"
 	"log"
   "fmt"
@@ -54,7 +55,7 @@ func (s *Server) getAuthCallbackFunc(w http.ResponseWriter, r *http.Request) {
   provider := chi.URLParam(r, "provider")
   r = r.WithContext(context.WithValue(context.Background(), "provider", provider))
 
-  user, err := gothic.CompleteUserAuth(w, r)
+  user, err := auth.CompleteAuthFlow(w, r)
   if err != nil {
     fmt.Fprintln(w, err)
     return