Re: [nfs-utils PATCH] Binding a privileged port in rpc.statd.

["J. Bruce Fields" <bfields@fieldses.org>]

On Thu, Jan 10, 2013 at 04:27:10PM +0200, Hemmo Nieminen wrote:
> Hi,
> 
> It seems that rpc.statd will fail to bind to a (free) port, if
> the first port it receives is listed in /etc/services. The
> bindresvport will keep on returning the same port if we close
> the socket too early.
> 
> The attached patch should fix this.

Looks right to me.--b.

> 
> -- 
> Hemmo

> >From abdaa0c27d66c71c9500b983fc4366cb3e514fff Mon Sep 17 00:00:00 2001
> From: Hemmo Nieminen <hemmo.nieminen@iki.fi>
> Date: Thu, 3 Jan 2013 10:00:17 +0200
> Subject: [PATCH] Fix socket binding loop.
> 
> Instead of closing the sockets before requesting a new one, keep them
> open until a suitable one is found. Otherwise bindresvport will return
> the same port over and over again.
> ---
>  utils/statd/rmtcall.c | 19 +++++++++++++------
>  1 file changed, 13 insertions(+), 6 deletions(-)
> 
> diff --git a/utils/statd/rmtcall.c b/utils/statd/rmtcall.c
> index 4ecb03c..fd576d9 100644
> --- a/utils/statd/rmtcall.c
> +++ b/utils/statd/rmtcall.c
> @@ -68,21 +68,19 @@ statd_get_socket(void)
>  {
>  	struct sockaddr_in	sin;
>  	struct servent *se;
> -	int loopcnt = 100;
> +	const int loopcnt = 100;
> +	int i, tmp_sockets[loopcnt];
>  
>  	if (sockfd >= 0)
>  		return sockfd;
>  
> -	while (loopcnt-- > 0) {
> -
> -		if (sockfd >= 0) close(sockfd);
> +	for (i = 0; i < loopcnt; ++i) {
>  
>  		if ((sockfd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) < 0) {
>  			xlog(L_ERROR, "%s: Can't create socket: %m", __func__);
> -			return -1;
> +			break;
>  		}
>  
> -
>  		memset(&sin, 0, sizeof(sin));
>  		sin.sin_family = AF_INET;
>  		sin.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
> @@ -96,7 +94,16 @@ statd_get_socket(void)
>  		if (se == NULL)
>  			break;
>  		/* rather not use that port, try again */
> +
> +		tmp_sockets[i] = sockfd;
>  	}
> +
> +	while (--i >= 0)
> +		close(tmp_sockets[i]);
> +
> +	if (sockfd < 0)
> +		return -1;
> +
>  	FD_SET(sockfd, &SVC_FDSET);
>  	return sockfd;
>  }
> -- 
> 1.8.1
>