feat: server-side feed credentials

If a feed requires credentials, OPDS Proxy can transparently
set them server side by reading the feed configuration.

This is useful in scenarios where the server operator sets up their
own authentication in front of OPDS Proxy and doesn't want to
have users remember separate credentials for each of the configured
feeds.

main.go

@@ -26,8 +26,14 @@ type auth struct {
 }
 
 type feedConfig struct {
-	Name string `koanf:"name"`
-	Url  string `koanf:"url"`
+	Name     string `koanf:"name"`
+	Url      string `koanf:"url"`
+	Username string `koanf:"username"`
+	Password string `koanf:"password"`
+}
+
+func (f feedConfig) HasCredentials() bool {
+	return f.Username != "" && f.Password != ""
 }
 
 var k = koanf.New(".")
@@ -70,7 +76,6 @@ func main() {
 
 		config.Auth.HashKey = hashKey
 		config.Auth.BlockKey = blockKey
-
 	}
 
 	server, err := NewServer(&config)

server.go

@@ -57,7 +57,7 @@ func NewServer(config *config) (*Server, error) {
 
 	router := http.NewServeMux()
 	router.HandleFunc("GET /{$}", handleHome(config.Feeds))
-	router.HandleFunc("GET /feed", handleFeed("tmp/", s))
+	router.HandleFunc("GET /feed", handleFeed("tmp/", config.Feeds, s))
 	router.HandleFunc("/auth", handleAuth(s))
 	router.Handle("GET /static/", http.FileServer(http.FS(html.StaticFiles())))
 
@@ -87,7 +87,7 @@ func handleHome(feeds []feedConfig) http.HandlerFunc {
 	}
 }
 
-func handleFeed(outputDir string, s *securecookie.SecureCookie) http.HandlerFunc {
+func handleFeed(outputDir string, feeds []feedConfig, s *securecookie.SecureCookie) http.HandlerFunc {
 	kepubConverter := &convert.KepubConverter{}
 	mobiConverter := &convert.MobiConverter{}
 
@@ -110,7 +110,7 @@ func handleFeed(outputDir string, s *securecookie.SecureCookie) http.HandlerFunc
 			queryURL = replaceSearchPlaceHolder(queryURL, searchTerm)
 		}
 
-		resp, err := fetchFromUrl(queryURL, getCredentials(r, s))
+		resp, err := fetchFromUrl(queryURL, getCredentials(r, feeds, s))
 		if err != nil {
 			handleError(r, w, "Failed to fetch", err)
 			return
@@ -231,7 +231,33 @@ func handleAuth(s *securecookie.SecureCookie) http.HandlerFunc {
 	}
 }
 
-func getCredentials(r *http.Request, s *securecookie.SecureCookie) *Credentials {
+func getCredentials(r *http.Request, feeds []feedConfig, s *securecookie.SecureCookie) *Credentials {
+	if !r.URL.Query().Has("q") {
+		return nil
+	}
+
+	feedUrl, err := url.Parse(r.URL.Query().Get("q"))
+	if err != nil {
+		return nil
+	}
+
+	// Try to get credentials from the config first
+	for _, feed := range feeds {
+		if !feed.HasCredentials() {
+			continue
+		}
+
+		configUrl, err := url.Parse(feed.Url)
+		if err != nil {
+			continue
+		}
+
+		if configUrl.Hostname() == feedUrl.Hostname() {
+			return &Credentials{Username: feed.Username, Password: feed.Password}
+		}
+	}
+
+	// Otherwise, try to get credentials from the cookie
 	cookie, err := r.Cookie("auth-creds")
 	if err != nil {
 		return nil
@@ -242,15 +268,6 @@ func getCredentials(r *http.Request, s *securecookie.SecureCookie) *Credentials
 		return nil
 	}
 
-	if !r.URL.Query().Has("q") {
-		return nil
-	}
-
-	feedUrl, err := url.Parse(r.URL.Query().Get("q"))
-	if err != nil {
-		return nil
-	}
-
 	return value[feedUrl.Hostname()]
 }