Fix HTTP header handling

client.go

@@ -10,11 +10,12 @@ import (
 )
 
 type DynClient struct {
-	client *http.Client
+	client    *http.Client
+	userAgent string
 }
 
-func NewDynClient() *DynClient {
-	return &DynClient{&http.Client{}}
+func NewDynClient(userAgent string) *DynClient {
+	return &DynClient{&http.Client{}, userAgent}
 }
 
 func (c *DynClient) Update(record Record, ip net.IP) (string, string, error) {
@@ -40,6 +41,15 @@ func (c *DynClient) Update(record Record, ip net.IP) (string, string, error) {
 		return "", urlWithoutPassword, err
 	}
 
+	request.Header.Set("User-Agent", c.userAgent)
+	for _, header := range record.Headers {
+		name, value, found := strings.Cut(header, ":")
+		if !found {
+			return "", urlWithoutPassword, errors.New("Invalid header: " + header)
+		}
+		request.Header.Set(name, value)
+	}
+
 	response, err := c.client.Do(request)
 	if err != nil {
 		return "", urlWithoutPassword, err

main.go

@@ -13,7 +13,7 @@ func main() {
 		return
 	}
 
-	client := NewDynClient()
+	client := NewDynClient(settings.UserAgent)
 
 	UpdateOnStartup(settings, client)