sshfwd_write(pr->c, data, len);
if (sshfwd_write(pr->c, data, len) > 0) { pr->throttled = 1; sk_set_frozen(pr->s, 1); }
static int x11_receive(Plug plug, int urgent, char *data, int len){    struct X11Private *pr = (struct X11Private *) plug;    sshfwd_write(pr->c, data, len);    return 1;}