void SetCookies(List <KeyValuePair <string, string> > cookies) { //Remove any existing Cookie header IEnumerable <string> existing; if (headers.TryGetValues("Cookie", out existing)) { headers.Remove("Cookie"); } //Build cookie string StringBuilder sb = new StringBuilder(); for (int i = 0; i < cookies.Count; i++) { CheckCharacters(cookies[i].Key, true); CheckCharacters(cookies[i].Value, false); sb.Append(cookies[i].Key); sb.Append('='); sb.Append(cookies[i].Value); if (i != cookies.Count - 1) { sb.Append("; "); } } headers.Add("Cookie", sb.ToString()); }