Re: [PATCH v5 06/13] conf: Allow multiple -a/--address options per address family

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

[-- Attachment #1: Type: text/plain, Size: 5087 bytes --]

On Sun, Feb 22, 2026 at 12:44:38PM -0500, Jon Maloy wrote:
> Allow specifying multiple addresses per family with -a/--address.
> The first address of each family is used for DHCP/DHCPv6 assignment.
> 
> Signed-off-by: Jon Maloy <jmaloy@redhat.com>
> 
> ---
> v2: - Adapted to previous code changes
> v3: - Adapted to single-array strategy
>     - Changes according to feedback from S. Brivio and G Gibson.
> v4: - Stripped down and adapted after feedback from David G.
> ---
>  conf.c  | 41 ++++++++++++++++++++++++-----------------
>  pasta.c | 17 ++++++++++-------
>  2 files changed, 34 insertions(+), 24 deletions(-)
> 
> diff --git a/conf.c b/conf.c
> index eb967c7..35ef994 100644
> --- a/conf.c
> +++ b/conf.c
> @@ -915,9 +915,10 @@ static void usage(const char *name, FILE *f, int status)
>  		"    default: 65520: maximum 802.3 MTU minus 802.3 header\n"
>  		"                    length, rounded to 32 bits (IPv4 words)\n"
>  		"  -a, --address ADDR	Assign IPv4 or IPv6 address ADDR[/PREFIXLEN]\n"
> -		"    can be specified zero to two times (for IPv4 and IPv6)\n"
> +		"    can be specified up to a maximum of 32 times\n"

You can use macro stringification to keep this accurate even if
INANY_MAX_ADDRS is altered.

Oh.. didn't note this in 1/13, but like the name of struct
inany_addr_entry, the "inany" isn't really pertinent in
INANY_MAX_ADDRS.  Maybe MAX_GUEST_ADDRS?

>  		"    default: use addresses from interface with default route\n"
> -		"  -n, --netmask MASK	Assign IPv4 MASK, dot-decimal or bits\n"
> +		"  -n, --netmask MASK	Assign IPv4 MASK, dot-decimal or bits\n");
> +	FPRINTF(f,
>  		"    default: netmask from matching address on the host\n"
>  		"  -M, --mac-addr ADDR	Use source MAC address ADDR\n"
>  		"    default: 9a:55:9a:55:9a:55 (locally administered)\n"
> @@ -1874,32 +1875,38 @@ void conf(struct ctx *c, int argc, char **argv)
>  			    IN6_IS_ADDR_V4COMPAT(&addr.a6))
>  				die("Invalid address: %s", optarg);
>  
> -			/* Legacy behaviour: overwrite existing address if any */
> -			if (inany_v4(&addr)) {
> -				e = first_v4(c);
> -				if (!e)
> -					e = &c->addrs[c->addr_count++];
> -				if (c->mode == MODE_PASTA)
> -					c->ip4.no_copy_addrs = true;
> -			} else {
> -				e = first_v6(c);
> -				if (!e)
> -					e = &c->addrs[c->addr_count++];
> -				if (c->mode == MODE_PASTA)
> -					c->ip6.no_copy_addrs = true;
> -			}
> +			for_each_addr(e, c, AF_UNSPEC)
> +				if (inany_equals(&addr, &e->addr))
> +					die("Address exists: %s", optarg);
> +
> +			if (c->addr_count >= INANY_MAX_ADDRS)
> +				die("Max addresses is %d", INANY_MAX_ADDRS);
> +
> +			e = &c->addrs[c->addr_count++];
>  			e->prefix_len = prefix_len;
>  			e->addr = addr;
>  			e->flags = CONF_ADDR_USER;
> +
> +			if (c->mode != MODE_PASTA)
> +				break;

I don't think you need this - the logic below will do nothing in passt
mode, but it should be harmless.

> +			if (inany_v4(&addr))
> +				c->ip4.no_copy_addrs = true;
> +			else
> +				c->ip6.no_copy_addrs = true;
>  			break;
>  		}
>  		case 'n': {
>  			struct inany_addr_entry *e;
> -			int plen;
> +			int plen, i = 0;
>  
>  			if (addr_has_prefix_len)
>  				die("Redundant prefix length specification");
>  
> +			for_each_addr(e, c, AF_INET)
> +				if (++i > 1)

'i' is usually a loop index, but here its a count.  Maybe 'n',
instead?

Having -n apply to the most recent address would also be an acceptable
choice, IMO.

> +					die("Use -n only when one address");
> +
>  			plen = conf_ip4_prefix(optarg);
>  			if (plen < 0)
>  				die("Invalid prefix length: %s", optarg);
> diff --git a/pasta.c b/pasta.c
> index 54010de..7a081e7 100644
> --- a/pasta.c
> +++ b/pasta.c
> @@ -342,12 +342,14 @@ void pasta_ns_conf(struct ctx *c)
>  
>  		if (c->ifi4) {
>  			if (c->ip4.no_copy_addrs) {
> -				e = first_v4(c);
> -				if (e)
> +				for_each_addr(e, c, AF_INET) {
>  					rc = nl_addr_set(nl_sock_ns,
>  							 c->pasta_ifi, AF_INET,
>  							 inany_v4(&e->addr),
> -							 e->prefix_len - 96);
> +							 inany_prefix4(e));

If you update nl_addr_set() to take an inany, you can do this in a
single loop.

> +					if (rc < 0)
> +						break;
> +				}
>  			} else {
>  				rc = nl_addr_dup(nl_sock, c->ifi4,
>  						 nl_sock_ns, c->pasta_ifi,
> @@ -400,13 +402,14 @@ ipv4_done:
>  					  0, IFF_NOARP);
>  
>  			if (c->ip6.no_copy_addrs) {
> -				e = first_v6(c);
> -				if (e)
> +				for_each_addr(e, c, AF_INET6) {
>  					rc = nl_addr_set(nl_sock_ns,
>  							 c->pasta_ifi,
> -							 AF_INET6,
> -							 &e->addr.a6,
> +							 AF_INET6, &e->addr.a6,
>  							 e->prefix_len);
> +					if (rc < 0)
> +						break;
> +				}
>  			} else {
>  				rc = nl_addr_dup(nl_sock, c->ifi6,
>  						 nl_sock_ns, c->pasta_ifi,
> -- 
> 2.52.0
> 

-- 
David Gibson (he or they)	| 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

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 833 bytes --]