Re: [PATCH v3 08/11] fwd_rule: Move ephemeral port probing to fwd_rule.c

[Laurent Vivier <lvivier@redhat.com>]

On 4/17/26 07:05, David Gibson wrote:
> We want to move parsing of forward rule options to fwd_rule.c so it can
> eventually be shared with a configuration client.  As a preliminary step,
> move the ephemeral port probing there, which that will need to use.
> 
> Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

Reviewed-by: Laurent Vivier <lvivier@redhat.com>

> ---
>   fwd.c      | 73 --------------------------------------------------
>   fwd.h      |  6 -----
>   fwd_rule.c | 78 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
>   fwd_rule.h |  6 +++++
>   4 files changed, 84 insertions(+), 79 deletions(-)
> 
> diff --git a/fwd.c b/fwd.c
> index aa966731..9a7053fd 100644
> --- a/fwd.c
> +++ b/fwd.c
> @@ -34,12 +34,6 @@
>   #include "arp.h"
>   #include "ndp.h"
>   
> -/* Ephemeral port range: values from RFC 6335 */
> -static in_port_t fwd_ephemeral_min = (1 << 15) + (1 << 14);
> -static in_port_t fwd_ephemeral_max = NUM_PORTS - 1;
> -
> -#define PORT_RANGE_SYSCTL	"/proc/sys/net/ipv4/ip_local_port_range"
> -
>   #define NEIGH_TABLE_SLOTS    1024
>   #define NEIGH_TABLE_SIZE     (NEIGH_TABLE_SLOTS / 2)
>   static_assert((NEIGH_TABLE_SLOTS & (NEIGH_TABLE_SLOTS - 1)) == 0,
> @@ -249,73 +243,6 @@ void fwd_neigh_table_init(const struct ctx *c)
>   		fwd_neigh_table_update(c, &mga, c->our_tap_mac, true);
>   }
>   
> -/** fwd_probe_ephemeral() - Determine what ports this host considers ephemeral
> - *
> - * Work out what ports the host thinks are emphemeral and record it for later
> - * use by fwd_port_is_ephemeral().  If we're unable to probe, assume the range
> - * recommended by RFC 6335.
> - */
> -void fwd_probe_ephemeral(void)
> -{
> -	char *line, *tab, *end;
> -	struct lineread lr;
> -	long min, max;
> -	ssize_t len;
> -	int fd;
> -
> -	fd = open(PORT_RANGE_SYSCTL, O_RDONLY | O_CLOEXEC);
> -	if (fd < 0) {
> -		warn_perror("Unable to open %s", PORT_RANGE_SYSCTL);
> -		return;
> -	}
> -
> -	lineread_init(&lr, fd);
> -	len = lineread_get(&lr, &line);
> -	close(fd);
> -
> -	if (len < 0)
> -		goto parse_err;
> -
> -	tab = strchr(line, '\t');
> -	if (!tab)
> -		goto parse_err;
> -	*tab = '\0';
> -
> -	errno = 0;
> -	min = strtol(line, &end, 10);
> -	if (*end || errno)
> -		goto parse_err;
> -
> -	errno = 0;
> -	max = strtol(tab + 1, &end, 10);
> -	if (*end || errno)
> -		goto parse_err;
> -
> -	if (min < 0 || min >= (long)NUM_PORTS ||
> -	    max < 0 || max >= (long)NUM_PORTS)
> -		goto parse_err;
> -
> -	fwd_ephemeral_min = min;
> -	fwd_ephemeral_max = max;
> -
> -	return;
> -
> -parse_err:
> -	warn("Unable to parse %s", PORT_RANGE_SYSCTL);
> -}
> -
> -/**
> - * fwd_port_map_ephemeral() - Mark ephemeral ports in a bitmap
> - * @map:	Bitmap to update
> - */
> -void fwd_port_map_ephemeral(uint8_t *map)
> -{
> -	unsigned port;
> -
> -	for (port = fwd_ephemeral_min; port <= fwd_ephemeral_max; port++)
> -		bitmap_set(map, port);
> -}
> -
>   /* Forwarding table storage, generally accessed via pointers in struct ctx */
>   static struct fwd_table fwd_in;
>   static struct fwd_table fwd_out;
> diff --git a/fwd.h b/fwd.h
> index 3e365d35..e664d1d0 100644
> --- a/fwd.h
> +++ b/fwd.h
> @@ -20,12 +20,6 @@
>   
>   struct flowside;
>   
> -/* Number of ports for both TCP and UDP */
> -#define	NUM_PORTS	(1U << 16)
> -
> -void fwd_probe_ephemeral(void);
> -void fwd_port_map_ephemeral(uint8_t *map);
> -
>   #define FWD_RULE_BITS	8
>   #define MAX_FWD_RULES	MAX_FROM_BITS(FWD_RULE_BITS)
>   #define FWD_NO_HINT	(-1)
> diff --git a/fwd_rule.c b/fwd_rule.c
> index 47d8df1c..9d489827 100644
> --- a/fwd_rule.c
> +++ b/fwd_rule.c
> @@ -15,9 +15,87 @@
>    * Author: David Gibson <david@gibson.dropbear.id.au>
>    */
>   
> +#include <errno.h>
> +#include <fcntl.h>
>   #include <stdio.h>
> +#include <unistd.h>
>   
>   #include "fwd_rule.h"
> +#include "lineread.h"
> +#include "log.h"
> +
> +/* Ephemeral port range: values from RFC 6335 */
> +static in_port_t fwd_ephemeral_min = (1 << 15) + (1 << 14);
> +static in_port_t fwd_ephemeral_max = NUM_PORTS - 1;
> +
> +#define PORT_RANGE_SYSCTL	"/proc/sys/net/ipv4/ip_local_port_range"
> +
> +/** fwd_probe_ephemeral() - Determine what ports this host considers ephemeral
> + *
> + * Work out what ports the host thinks are emphemeral and record it for later
> + * use by fwd_port_is_ephemeral().  If we're unable to probe, assume the range
> + * recommended by RFC 6335.
> + */
> +void fwd_probe_ephemeral(void)
> +{
> +	char *line, *tab, *end;
> +	struct lineread lr;
> +	long min, max;
> +	ssize_t len;
> +	int fd;
> +
> +	fd = open(PORT_RANGE_SYSCTL, O_RDONLY | O_CLOEXEC);
> +	if (fd < 0) {
> +		warn_perror("Unable to open %s", PORT_RANGE_SYSCTL);
> +		return;
> +	}
> +
> +	lineread_init(&lr, fd);
> +	len = lineread_get(&lr, &line);
> +	close(fd);
> +
> +	if (len < 0)
> +		goto parse_err;
> +
> +	tab = strchr(line, '\t');
> +	if (!tab)
> +		goto parse_err;
> +	*tab = '\0';
> +
> +	errno = 0;
> +	min = strtol(line, &end, 10);
> +	if (*end || errno)
> +		goto parse_err;
> +
> +	errno = 0;
> +	max = strtol(tab + 1, &end, 10);
> +	if (*end || errno)
> +		goto parse_err;
> +
> +	if (min < 0 || min >= (long)NUM_PORTS ||
> +	    max < 0 || max >= (long)NUM_PORTS)
> +		goto parse_err;
> +
> +	fwd_ephemeral_min = min;
> +	fwd_ephemeral_max = max;
> +
> +	return;
> +
> +parse_err:
> +	warn("Unable to parse %s", PORT_RANGE_SYSCTL);
> +}
> +
> +/**
> + * fwd_port_map_ephemeral() - Mark ephemeral ports in a bitmap
> + * @map:	Bitmap to update
> + */
> +void fwd_port_map_ephemeral(uint8_t *map)
> +{
> +	unsigned port;
> +
> +	for (port = fwd_ephemeral_min; port <= fwd_ephemeral_max; port++)
> +		bitmap_set(map, port);
> +}
>   
>   /**
>    * fwd_rule_addr() - Return match address for a rule
> diff --git a/fwd_rule.h b/fwd_rule.h
> index edba6782..5c7b67aa 100644
> --- a/fwd_rule.h
> +++ b/fwd_rule.h
> @@ -17,6 +17,9 @@
>   #include "inany.h"
>   #include "bitmap.h"
>   
> +/* Number of ports for both TCP and UDP */
> +#define	NUM_PORTS	(1U << 16)
> +
>   /* Forwarding capability bits */
>   #define FWD_CAP_IPV4		BIT(0)
>   #define FWD_CAP_IPV6		BIT(1)
> @@ -51,6 +54,9 @@ struct fwd_rule {
>   	uint8_t flags;
>   };
>   
> +void fwd_probe_ephemeral(void);
> +void fwd_port_map_ephemeral(uint8_t *map);
> +
>   #define FWD_RULE_STRLEN					    \
>   	(IPPROTO_STRLEN - 1				    \
>   	 + INANY_ADDRSTRLEN - 1				    \