Do not follow redirects when trying known feed URLs

Some websites redirects unknown URLs to the home page.
As result, the list of known URLs is returned to the subscription list.
We don't want the user to choose between invalid feed URLs.

http/client/client.go

@@ -52,7 +52,8 @@ type Client struct {
 	requestPassword            string
 	requestUserAgent           string
 
-	useProxy bool
+	useProxy             bool
+	doNotFollowRedirects bool
 
 	ClientTimeout     int
 	ClientMaxBodySize int64
@@ -124,12 +125,18 @@ func (c *Client) WithCacheHeaders(etagHeader, lastModifiedHeader string) *Client
 	return c
 }
 
-// WithProxy enable proxy for the current HTTP request.
+// WithProxy enables proxy for the current HTTP request.
 func (c *Client) WithProxy() *Client {
 	c.useProxy = true
 	return c
 }
 
+// WithoutRedirects disables HTTP redirects.
+func (c *Client) WithoutRedirects() *Client {
+	c.doNotFollowRedirects = true
+	return c
+}
+
 // WithUserAgent defines the User-Agent header to use for HTTP requests.
 func (c *Client) WithUserAgent(userAgent string) *Client {
 	if userAgent != "" {
@@ -266,7 +273,10 @@ func (c *Client) buildRequest(method string, body io.Reader) (*http.Request, err
 }
 
 func (c *Client) buildClient() http.Client {
-	client := http.Client{Timeout: time.Duration(c.ClientTimeout) * time.Second}
+	client := http.Client{
+		Timeout: time.Duration(c.ClientTimeout) * time.Second,
+	}
+
 	transport := &http.Transport{
 		Proxy: http.ProxyFromEnvironment,
 		DialContext: (&net.Dialer{
@@ -284,6 +294,12 @@ func (c *Client) buildClient() http.Client {
 		IdleConnTimeout: 10 * time.Second,
 	}
 
+	if c.doNotFollowRedirects {
+		client.CheckRedirect = func(req *http.Request, via []*http.Request) error {
+			return http.ErrUseLastResponse
+		}
+	}
+
 	if c.useProxy && c.ClientProxyURL != "" {
 		proxyURL, err := url.Parse(c.ClientProxyURL)
 		if err != nil {

reader/subscription/finder.go

@@ -156,9 +156,16 @@ func tryWellKnownUrls(websiteURL, userAgent, username, password string) (Subscri
 		if err != nil {
 			continue
 		}
+
 		clt := client.NewClientWithConfig(fullURL, config.Opts)
 		clt.WithCredentials(username, password)
 		clt.WithUserAgent(userAgent)
+
+		// Some websites redirects unknown URLs to the home page.
+		// As result, the list of known URLs is returned to the subscription list.
+		// We don't want the user to choose between invalid feed URLs.
+		clt.WithoutRedirects()
+
 		response, err := clt.Get()
 		if err != nil {
 			continue