Use cookies for session storage

Remove the server side session storage and store all the session related data
in the client side cookies. This decreases the exposure of the auth tokens.
It also simplifies the installation process as bloat no longer requires write
access to the filesystem.

This is a breaking change, all the existing sessions will stop working.

1 files changed, 111 insertions, 0 deletions

diff --git a/service/client.go b/service/client.go
new file mode 100644
index 0000000..3affd57
--- /dev/null
+++ b/service/client.go
@@ -0,0 +1,111 @@
+package service
+
+import (
+	"context"
+	"encoding/base64"
+	"encoding/json"
+	"net/http"
+	"strings"
+	"time"
+
+	"bloat/mastodon"
+	"bloat/model"
+	"bloat/renderer"
+)
+
+type client struct {
+	*mastodon.Client
+	w    http.ResponseWriter
+	r    *http.Request
+	s    *model.Session
+	csrf string
+	ctx  context.Context
+	rctx *renderer.Context
+}
+
+func (c *client) setSession(sess *model.Session) error {
+	var sb strings.Builder
+	bw := base64.NewEncoder(base64.URLEncoding, &sb)
+	err := json.NewEncoder(bw).Encode(sess)
+	bw.Close()
+	if err != nil {
+		return err
+	}
+	http.SetCookie(c.w, &http.Cookie{
+		Name:    "session",
+		Value:   sb.String(),
+		Expires: time.Now().Add(365 * 24 * time.Hour),
+	})
+	return nil
+}
+
+func (c *client) getSession() (sess *model.Session, err error) {
+	cookie, _ := c.r.Cookie("session")
+	if cookie == nil {
+		return nil, errInvalidSession
+	}
+	br := base64.NewDecoder(base64.URLEncoding, strings.NewReader(cookie.Value))
+	err = json.NewDecoder(br).Decode(&sess)
+	return
+}
+
+func (c *client) unsetSession() {
+	http.SetCookie(c.w, &http.Cookie{
+		Name:    "session",
+		Value:   "",
+		Expires: time.Now(),
+	})
+}
+
+func (c *client) writeJson(data interface{}) error {
+	return json.NewEncoder(c.w).Encode(map[string]interface{}{
+		"data": data,
+	})
+}
+
+func (c *client) redirect(url string) {
+	c.w.Header().Add("Location", url)
+	c.w.WriteHeader(http.StatusFound)
+}
+
+func (c *client) authenticate(t int) (err error) {
+	csrf := c.r.FormValue("csrf_token")
+	ref := c.r.URL.RequestURI()
+	defer func() {
+		if c.s == nil {
+			c.s = &model.Session{
+				Settings: *model.NewSettings(),
+			}
+		}
+		c.rctx = &renderer.Context{
+			HideAttachments:  c.s.Settings.HideAttachments,
+			MaskNSFW:         c.s.Settings.MaskNSFW,
+			ThreadInNewTab:   c.s.Settings.ThreadInNewTab,
+			FluorideMode:     c.s.Settings.FluorideMode,
+			DarkMode:         c.s.Settings.DarkMode,
+			CSRFToken:        c.s.CSRFToken,
+			UserID:           c.s.UserID,
+			AntiDopamineMode: c.s.Settings.AntiDopamineMode,
+			UserCSS:          c.s.Settings.CSS,
+			Referrer:         ref,
+		}
+	}()
+	if t < SESSION {
+		return
+	}
+	sess, err := c.getSession()
+	if err != nil {
+		return err
+	}
+	c.s = sess
+	c.Client = mastodon.NewClient(&mastodon.Config{
+		Server:       "https://" + c.s.Instance,
+		ClientID:     c.s.ClientID,
+		ClientSecret: c.s.ClientSecret,
+		AccessToken:  c.s.AccessToken,
+	})
+	if t >= CSRF && (len(csrf) < 1 || csrf != c.s.CSRFToken) {
+		return errInvalidCSRFToken
+	}
+	return
+}