Add OIDC Refresh token cookies

README.md

@@ -15,7 +15,7 @@ import cshauth "github.com/computersciencehouse/csh-auth/v2"
 ### Initialize your csh-auth object
 
 ```go
-auth := cshauth.Init(
+auth, err := cshauth.Init(
     clientID            // the OIDC client ID
     clientSecret        // the OIDC client secret
     serverURL           // the "base" URL that this service is hosted from, e.g. "http://localhost:8000"
@@ -32,6 +32,7 @@ auth := cshauth.Init(
 ```go
 r.GET("/auth/login", auth.HandleLogin) // This endpoint should match the path for loginURL
 r.GET("/auth/callback", auth.HandleCallback) // This endpoint should match the path for callbackURL
+r.POST("/auth/refresh", auth.HandleRefresh)
 r.GET("/auth/logout", auth.HandleLogout)
 ```
 
@@ -46,6 +47,36 @@ This works because Gin will run the widest scope function to the most narrow sco
 
 For more/all routes: Check the [Gin Middleware documentation](https://gin-gonic.com/en/docs/middleware/) page.
 
+### Using refresh tokens
+
+By default, a refresh token is stored in the browser's cookies. This token can be used to fetch a new auth token wihout having to redirect the user through SSO.
+
+csh-auth handles this throught the refresh handler.
+```go
+router.POST("/auth/refresh", auth.HandleRefresh)
+```
+
+Whenever the auth token is expired, the browser should make a POST request to this endpoint. The server will update the browser's cookie with a new token.
+
+This is particularly useful for SPAs, where the token validity isn't being check with every page interaction.
+
+#### Example Implementation
+
+The following is an example implementation that could be used in the browser.
+
+```ts
+const response = await fetch("/api/endpoint")
+
+if (response.status === 401) { // token expired
+    fetch('/auth/refresh', { // this will update the browser's cookie without requiring a page refresh
+      method: 'POST',
+      credentials: 'include',
+    })
+}
+```
+
+In a real application, the original request would typically be retried after a successful refresh. This example only demonstrates the basic refresh mechanism.
+
 ### Get user information
 The information for a user is located at `gin.Context#Get("cshauth")`.
 This information includes the JWT information as well.

auth.go

@@ -130,9 +130,37 @@ func (auth *Auth) HandleCallback(c *gin.Context) {
 	}
 
 	c.SetCookie(CookieName, oauthJWT.AccessToken, int(oauthJWT.ExpiresIn), "", "", false, true)
+	// refresh token
+	c.SetCookie("Refresh", oauthJWT.RefreshToken, 0, "", "", auth.secure, true)
 	c.Redirect(http.StatusFound, c.Query("referer"))
 }
 
+func (auth *Auth) HandleRefresh(c *gin.Context) {
+	refreshToken, err := c.Cookie("Refresh")
+
+	if err != nil || refreshToken == "" {
+		c.AbortWithStatus(401)
+		return
+	}
+
+	token := &oauth2.Token{
+		RefreshToken: refreshToken,
+	}
+
+	tokenSource := auth.oauth.TokenSource(auth.ctx, token)
+	newToken, err := tokenSource.Token()
+	if err != nil {
+		log.Error("failed to refresh token: ", err)
+		c.SetCookie("Auth", "", 0, "", "", auth.secure, true)
+		c.SetCookie("Refresh", "", 0, "", "", auth.secure, true)
+		c.AbortWithStatus(http.StatusUnauthorized)
+		return
+	}
+
+	c.SetCookie(CookieName, newToken.AccessToken, int(time.Until(newToken.Expiry).Seconds()), "", "", auth.secure, true)
+	c.Status(204)
+}
+
 func (auth *Auth) HandleLogout(c *gin.Context) {
 	c.SetCookie(CookieName, "", 0, "", "", false, true)
 	c.Redirect(http.StatusFound, ProviderURI+"/protocol/openid-connect/logout?post_logout_redirect_uri="+auth.serverURL+"/&client_id="+auth.clientID+"")