url_fprintf(c->pb, "Content-Type: application/sdp\r\n");
url_fprintf(c->pb, "Content-Length: %d\r\n", content_length);
url_fprintf(c->pb, "\r\n");
url_fprintf(c->pb, "Content-Type: application/sdp\r\n");
url_fprintf(c->pb, "Content-Length: %d\r\n", content_length);
url_fprintf(c->pb, "\r\n");