Re: [PATCH] conf, tap: Add option to quit once the client closes the connection

[David Gibson <david@gibson.dropbear.id.au>]

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On Fri, Oct 07, 2022 at 09:16:41AM +0200, Stefano Brivio wrote:
> This is practical to avoid explicit lifecycle management in users,
> e.g. libvirtd, and is trivial to implement.
> 
> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

I actually wonder if this should be the default/only behaviour.

> ---
>  conf.c  | 17 ++++++++++++++++-
>  passt.1 |  5 +++++
>  passt.h |  1 +
>  tap.c   |  5 +++++
>  4 files changed, 27 insertions(+), 1 deletion(-)
> 
> diff --git a/conf.c b/conf.c
> index 4ec3153..53a8dcf 100644
> --- a/conf.c
> +++ b/conf.c
> @@ -712,6 +712,7 @@ static void usage(const char *name)
>  	if (strstr(name, "pasta"))
>  		goto pasta_opts;
>  
> +	info(   "  -1, --one-off	Quit after handling one single client");
>  	info(   "  -t, --tcp-ports SPEC	TCP port forwarding to guest");
>  	info(   "    can be specified multiple times");
>  	info(   "    SPEC can be:");
> @@ -1024,6 +1025,7 @@ void conf(struct ctx *c, int argc, char **argv)
>  		{"no-map-gw",	no_argument,		&c->no_map_gw,	1 },
>  		{"ipv4-only",	no_argument,		NULL,		'4' },
>  		{"ipv6-only",	no_argument,		NULL,		'6' },
> +		{"one-off",	no_argument,		NULL,		'1' },
>  		{"tcp-ports",	required_argument,	NULL,		't' },
>  		{"udp-ports",	required_argument,	NULL,		'u' },
>  		{"tcp-ns",	required_argument,	NULL,		'T' },
> @@ -1062,7 +1064,7 @@ void conf(struct ctx *c, int argc, char **argv)
>  		c->no_dhcp_dns = c->no_dhcp_dns_search = 1;
>  		optstring = "vdqfel:hI:p:P:m:a:n:M:g:i:D:S:46t:u:T:U:";
>  	} else {
> -		optstring = "vdqfel:hs:p:P:m:a:n:M:g:i:D:S:46t:u:";
> +		optstring = "vdqfel:hs:p:P:m:a:n:M:g:i:D:S:461t:u:";
>  	}
>  
>  	c->tcp.fwd_in.mode = c->tcp.fwd_out.mode = 0;
> @@ -1488,6 +1490,19 @@ void conf(struct ctx *c, int argc, char **argv)
>  		case '6':
>  			v6_only = true;
>  			break;
> +		case '1':
> +			if (c->mode != MODE_PASST) {
> +				err("--one-off is for passt mode only");
> +				usage(argv[0]);
> +			}
> +
> +			if (c->one_off) {
> +				err("Redundant --one-off option");
> +				usage(argv[0]);
> +			}
> +
> +			c->one_off = true;
> +			break;
>  		case 't':
>  		case 'u':
>  		case 'T':
> diff --git a/passt.1 b/passt.1
> index c63a439..41f8836 100644
> --- a/passt.1
> +++ b/passt.1
> @@ -302,6 +302,11 @@ Path for UNIX domain socket used by \fBqemu\fR(1) or \fBqrap\fR(1) to connect to
>  Default is to probe a free socket, not accepting connections, starting from
>  \fI/tmp/passt_1.socket\fR to \fI/tmp/passt_64.socket\fR.
>  
> +.TP
> +.BR \-1 ", " \-\-one-off
> +Quit after handling a single client connection, that is, once the client closes
> +the socket, or once we get a socket error.
> +
>  .TP
>  .BR \-t ", " \-\-tcp-ports " " \fIspec
>  Configure TCP port forwarding to guest. \fIspec\fR can be one of:
> diff --git a/passt.h b/passt.h
> index de79e7b..67281db 100644
> --- a/passt.h
> +++ b/passt.h
> @@ -196,6 +196,7 @@ struct ctx {
>  	char sock_path[UNIX_PATH_MAX];
>  	char pcap[PATH_MAX];
>  	char pid_file[PATH_MAX];
> +	int one_off;
>  
>  	int pasta_netns_fd;
>  
> diff --git a/tap.c b/tap.c
> index bdcc161..78de42c 100644
> --- a/tap.c
> +++ b/tap.c
> @@ -1011,5 +1011,10 @@ void tap_handler(struct ctx *c, int fd, uint32_t events,
>  
>  	return;
>  reinit:
> +	if (c->one_off) {
> +		info("Client closed connection, exiting");
> +		exit(EXIT_SUCCESS);
> +	}
> +
>  	tap_sock_init(c);
>  }

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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