Re: [PATCH v2 2/9] ip: Introduce unified multi-address data structures

[Stefano Brivio <sbrivio@redhat.com>]

On Sun, 18 Jan 2026 17:16:05 -0500
Jon Maloy <jmaloy@redhat.com> wrote:

> As preparation for supporting multiple addresses per interface, we
> replace the single addr/prefix_len fields with arrays.
> 
> - We add an ip4_addr_entry and an ip6_addr_entry struct containing
>   address and prefix length.
> 
> - We set the array sizes to IP4_MAX_ADDRS=8 and IP6_MAX_ADDRS=16,
>   respectively.

Is there a particular reason behind this choice? Wouldn't it be more
convenient, especially for documentation purposes and to avoid
confusing users, to stick to the same number of addresses for both
versions?

> The only functional change is that the IPv6 prefix length now is
> properly stored instead of being hardcoded to 64 even when set
> via the -a option.
> 
> Signed-off-by: Jon Maloy <jmaloy@redhat.com>
> 
> ---
> v2: Using inany_addr instead of protocol specific addresses as
>     entry address field.

No particular comments here, just three minor nits below, but, in
general: is the plan to have a single array for both IPv4 and IPv6?

If not, does it really make sense to use the inany type for arrays that
only contain IPv4 or IPv6 addresses, separately?

> ---
>  arp.c    |  4 +--
>  conf.c   | 78 +++++++++++++++++++++++++++++++++++---------------------
>  dhcp.c   |  8 +++---
>  dhcpv6.c |  6 ++---
>  fwd.c    | 12 ++++-----
>  inany.h  | 16 ++++++++++++
>  ip.h     |  4 +++
>  ndp.c    |  6 ++---
>  passt.h  | 16 +++++++-----
>  pasta.c  | 12 +++++----
>  tap.c    |  4 +--
>  11 files changed, 106 insertions(+), 60 deletions(-)
> 
> diff --git a/arp.c b/arp.c
> index bb042e9..bc77a9f 100644
> --- a/arp.c
> +++ b/arp.c
> @@ -54,7 +54,7 @@ static bool ignore_arp(const struct ctx *c,
>  		return true;
>  
>  	/* Don't resolve the guest's assigned address, either. */
> -	if (!memcmp(am->tip, &c->ip4.addr, sizeof(am->tip)))
> +	if (!memcmp(am->tip, inany_v4(&c->ip4.addrs[0].addr), sizeof(am->tip)))
>  		return true;
>  
>  	return false;
> @@ -145,7 +145,7 @@ void arp_send_init_req(const struct ctx *c)
>  	memcpy(req.am.sha,	c->our_tap_mac,		sizeof(req.am.sha));
>  	memcpy(req.am.sip,	&c->ip4.our_tap_addr,	sizeof(req.am.sip));
>  	memcpy(req.am.tha,	MAC_BROADCAST,		sizeof(req.am.tha));
> -	memcpy(req.am.tip,	&c->ip4.addr,		sizeof(req.am.tip));
> +	memcpy(req.am.tip,	inany_v4(&c->ip4.addrs[0].addr), sizeof(req.am.tip));

Nit: it doesn't look like a table anymore, so either drop all the tabs,
or mix tabs and spaces:

	memcpy(req.am.sha, c->our_tap_mac,		    sizeof(req.am.sha));
	memcpy(req.am.sip, &c->ip4.our_tap_addr,	    sizeof(req.am.sip));
	memcpy(req.am.tha, MAC_BROADCAST,		    sizeof(req.am.tha));
	memcpy(req.am.tip, inany_v4(&c->ip4.addrs[0].addr), sizeof(req.am.tip));

>  
>  	debug("Sending initial ARP request for guest MAC address");
>  	tap_send_single(c, &req, sizeof(req));
> diff --git a/conf.c b/conf.c
> index 7178a0e..9fc5dca 100644
> --- a/conf.c
> +++ b/conf.c
> @@ -763,33 +763,33 @@ static unsigned int conf_ip4(unsigned int ifi, struct ip4_ctx *ip4)
>  		}
>  	}
>  
> -	if (IN4_IS_ADDR_UNSPECIFIED(&ip4->addr)) {
> +	if (!ip4->addr_count) {
> +		struct in_addr addr;
> +		int prefix_len = 0;
>  		int rc = nl_addr_get(nl_sock, ifi, AF_INET,
> -				     &ip4->addr, &ip4->prefix_len, NULL);
> +				     &addr, &prefix_len, NULL);
>  		if (rc < 0) {
>  			debug("Couldn't discover IPv4 address: %s",
>  			      strerror_(-rc));
>  			return 0;
>  		}
> +		ip4->addrs[0].addr = inany_from_v4(addr);
> +		ip4->addrs[0].prefix_len = prefix_len;
> +		ip4->addrs[0].flags = INANY_ADDR_HOST;
> +		ip4->addr_count = 1;
>  	}
>  
> -	if (!ip4->prefix_len) {
> -		in_addr_t addr = ntohl(ip4->addr.s_addr);
> -		if (IN_CLASSA(addr))
> -			ip4->prefix_len = (32 - IN_CLASSA_NSHIFT);
> -		else if (IN_CLASSB(addr))
> -			ip4->prefix_len = (32 - IN_CLASSB_NSHIFT);
> -		else if (IN_CLASSC(addr))
> -			ip4->prefix_len = (32 - IN_CLASSC_NSHIFT);
> -		else
> -			ip4->prefix_len = 32;
> +	if (!ip4->addrs[0].prefix_len) {
> +		const struct in_addr *a4 = inany_v4(&ip4->addrs[0].addr);
> +
> +		ip4->addrs[0].prefix_len = ip4_default_prefix_len(a4);
>  	}
>  
> -	ip4->addr_seen = ip4->addr;
> +	ip4->addr_seen = *inany_v4(&ip4->addrs[0].addr);
>  
>  	ip4->our_tap_addr = ip4->guest_gw;
>  
> -	if (IN4_IS_ADDR_UNSPECIFIED(&ip4->addr))
> +	if (inany_is_unspecified(&ip4->addrs[0].addr))
>  		return 0;
>  
>  	return ifi;
> @@ -801,9 +801,11 @@ static unsigned int conf_ip4(unsigned int ifi, struct ip4_ctx *ip4)
>   */
>  static void conf_ip4_local(struct ip4_ctx *ip4)
>  {
> -	ip4->addr_seen = ip4->addr = IP4_LL_GUEST_ADDR;
> +	ip4->addrs[0].addr = inany_from_v4(IP4_LL_GUEST_ADDR);
> +	ip4->addr_seen = *inany_v4(&ip4->addrs[0].addr);
>  	ip4->our_tap_addr = ip4->guest_gw = IP4_LL_GUEST_GW;
> -	ip4->prefix_len = IP4_LL_PREFIX_LEN;
> +	ip4->addrs[0].prefix_len = IP4_LL_PREFIX_LEN;
> +	ip4->addr_count = 1;
>  
>  	ip4->no_copy_addrs = ip4->no_copy_routes = true;
>  }
> @@ -838,19 +840,25 @@ static unsigned int conf_ip6(unsigned int ifi, struct ip6_ctx *ip6)
>  	}
>  
>  	rc = nl_addr_get(nl_sock, ifi, AF_INET6,
> -			 IN6_IS_ADDR_UNSPECIFIED(&ip6->addr) ? &ip6->addr : NULL,
> +			 ip6->addr_count ? NULL : &ip6->addrs[0].addr.a6,
>  			 &prefix_len, &ip6->our_tap_ll);
>  	if (rc < 0) {
>  		debug("Couldn't discover IPv6 address: %s", strerror_(-rc));
>  		return 0;
>  	}
>  
> -	ip6->addr_seen = ip6->addr;
> +	if (!ip6->addr_count) {
> +		ip6->addrs[0].prefix_len = prefix_len ? prefix_len : 64;
> +		ip6->addrs[0].flags = INANY_ADDR_HOST;
> +		ip6->addr_count = 1;
> +	}
> +
> +	ip6->addr_seen = ip6->addrs[0].addr.a6;
>  
>  	if (IN6_IS_ADDR_LINKLOCAL(&ip6->guest_gw))
>  		ip6->our_tap_ll = ip6->guest_gw;
>  
> -	if (IN6_IS_ADDR_UNSPECIFIED(&ip6->addr) ||
> +	if (IN6_IS_ADDR_UNSPECIFIED(&ip6->addrs[0].addr.a6) ||
>  	    IN6_IS_ADDR_UNSPECIFIED(&ip6->our_tap_ll))
>  		return 0;
>  
> @@ -1193,11 +1201,13 @@ static void conf_print(const struct ctx *c)
>  		if (!c->no_dhcp) {
>  			uint32_t mask;
>  
> -			mask = htonl(0xffffffff << (32 - c->ip4.prefix_len));
> +			mask = htonl(0xffffffff <<
> +				     (32 - c->ip4.addrs[0].prefix_len));
>  
>  			info("DHCP:");
>  			info("    assign: %s",
> -			     inet_ntop(AF_INET, &c->ip4.addr, buf4, sizeof(buf4)));
> +			     inet_ntop(AF_INET, inany_v4(&c->ip4.addrs[0].addr),
> +				       buf4, sizeof(buf4)));
>  			info("    mask: %s",
>  			     inet_ntop(AF_INET, &mask,        buf4, sizeof(buf4)));
>  			info("    router: %s",
> @@ -1235,7 +1245,8 @@ static void conf_print(const struct ctx *c)
>  			goto dns6;
>  
>  		info("    assign: %s",
> -		     inet_ntop(AF_INET6, &c->ip6.addr, buf6, sizeof(buf6)));
> +		     inet_ntop(AF_INET6, &c->ip6.addrs[0].addr.a6,
> +			       buf6, sizeof(buf6)));
>  		info("    router: %s",
>  		     inet_ntop(AF_INET6, &c->ip6.guest_gw, buf6, sizeof(buf6)));
>  		info("    our link-local: %s",
> @@ -1870,15 +1881,20 @@ void conf(struct ctx *c, int argc, char **argv)
>  				die("Invalid address: %s", optarg);
>  
>  			if (af == AF_INET6) {
> -				c->ip6.addr = addr.a6;
> +				c->ip6.addrs[0].addr.a6 = addr.a6;
> +				c->ip6.addrs[0].flags |= INANY_ADDR_CONFIGURED;
> +				c->ip6.addr_count = 1;
>  				if (c->mode == MODE_PASTA)
>  					c->ip6.no_copy_addrs = true;
>  				break;
>  			}
>  
>  			a4 = inany_v4(&addr);
> +
>  			if (af == AF_INET && a4) {
> -				c->ip4.addr = *a4;
> +				c->ip4.addrs[0].addr = inany_from_v4(*a4);
> +				c->ip4.addrs[0].flags |= INANY_ADDR_CONFIGURED;
> +				c->ip4.addr_count = 1;
>  				if (prefix_len) {
>  					if (prefix_from_opt)
>  						die("Can't mix CIDR with -n");
> @@ -1886,21 +1902,25 @@ void conf(struct ctx *c, int argc, char **argv)
>  				} else {
>  					prefix_len = ip4_default_prefix_len(a4);
>  				}
> -				c->ip4.prefix_len = prefix_len;
> +				c->ip4.addrs[0].prefix_len = prefix_len;
>  				break;
>  			}
>  
>  			die("Invalid address: %s", optarg);
>  			break;
>  		}
> -		case 'n':
> +		case 'n': {
> +			int plen;
> +
>  			if (prefix_from_cidr)
>  				die("Can't use both -n and CIDR prefix length");
> -			c->ip4.prefix_len = conf_ip4_prefix(optarg);
> -			if (c->ip4.prefix_len < 0)
> +			plen = conf_ip4_prefix(optarg);
> +			if (plen < 0)
>  				die("Invalid netmask: %s", optarg);
> +			c->ip4.addrs[0].prefix_len = plen;
>  			prefix_from_opt = true;
>  			break;
> +		}
>  		case 'M':
>  			parse_mac(c->our_tap_mac, optarg);
>  			break;
> @@ -2185,7 +2205,7 @@ void conf(struct ctx *c, int argc, char **argv)
>  	if (!c->ifi6) {
>  		c->no_ndp = 1;
>  		c->no_dhcpv6 = 1;
> -	} else if (IN6_IS_ADDR_UNSPECIFIED(&c->ip6.addr)) {
> +	} else if (IN6_IS_ADDR_UNSPECIFIED(&c->ip6.addrs[0].addr.a6)) {
>  		c->no_dhcpv6 = 1;
>  	}
>  
> diff --git a/dhcp.c b/dhcp.c
> index 6b9c2e3..d2afc3b 100644
> --- a/dhcp.c
> +++ b/dhcp.c
> @@ -352,7 +352,7 @@ int dhcp(const struct ctx *c, struct iov_tail *data)
>  	reply.secs		= 0;
>  	reply.flags		= m->flags;
>  	reply.ciaddr		= m->ciaddr;
> -	reply.yiaddr		= c->ip4.addr;
> +	reply.yiaddr		= *inany_v4(&c->ip4.addrs[0].addr);
>  	reply.siaddr		= 0;
>  	reply.giaddr		= m->giaddr;
>  	memcpy(&reply.chaddr,	m->chaddr,	sizeof(reply.chaddr));
> @@ -404,7 +404,7 @@ int dhcp(const struct ctx *c, struct iov_tail *data)
>  
>  	info("    from %s", eth_ntop(m->chaddr, macstr, sizeof(macstr)));
>  
> -	mask.s_addr = htonl(0xffffffff << (32 - c->ip4.prefix_len));
> +	mask.s_addr = htonl(0xffffffff << (32 - c->ip4.addrs[0].prefix_len));
>  	memcpy(opts[1].s,  &mask,                sizeof(mask));
>  	memcpy(opts[3].s,  &c->ip4.guest_gw,     sizeof(c->ip4.guest_gw));
>  	memcpy(opts[54].s, &c->ip4.our_tap_addr, sizeof(c->ip4.our_tap_addr));
> @@ -412,7 +412,7 @@ int dhcp(const struct ctx *c, struct iov_tail *data)
>  	/* If the gateway is not on the assigned subnet, send an option 121
>  	 * (Classless Static Routing) adding a dummy route to it.
>  	 */
> -	if ((c->ip4.addr.s_addr & mask.s_addr)
> +	if ((inany_v4(&c->ip4.addrs[0].addr)->s_addr & mask.s_addr)
>  	    != (c->ip4.guest_gw.s_addr & mask.s_addr)) {
>  		/* a.b.c.d/32:0.0.0.0, 0:a.b.c.d */
>  		opts[121].slen = 14;
> @@ -469,7 +469,7 @@ int dhcp(const struct ctx *c, struct iov_tail *data)
>  	if (m->flags & FLAG_BROADCAST)
>  		dst = in4addr_broadcast;
>  	else
> -		dst = c->ip4.addr;
> +		dst = *inany_v4(&c->ip4.addrs[0].addr);
>  
>  	tap_udp4_send(c, c->ip4.our_tap_addr, 67, dst, 68, &reply, dlen);
>  
> diff --git a/dhcpv6.c b/dhcpv6.c
> index e4df0db..f45dece 100644
> --- a/dhcpv6.c
> +++ b/dhcpv6.c
> @@ -625,7 +625,7 @@ int dhcpv6(struct ctx *c, struct iov_tail *data,
>  		if (mh->type == TYPE_CONFIRM && server_id)
>  			return -1;
>  
> -		if (dhcpv6_ia_notonlink(data, &c->ip6.addr)) {
> +		if (dhcpv6_ia_notonlink(data, &c->ip6.addrs[0].addr.a6)) {
>  
>  			dhcpv6_send_ia_notonlink(c, data, &client_id_base,
>  						 ntohs(client_id->l), mh->xid);
> @@ -679,7 +679,7 @@ int dhcpv6(struct ctx *c, struct iov_tail *data,
>  
>  	tap_udp6_send(c, src, 547, tap_ip6_daddr(c, src), 546,
>  		      mh->xid, &resp, n);
> -	c->ip6.addr_seen = c->ip6.addr;
> +	c->ip6.addr_seen = c->ip6.addrs[0].addr.a6;
>  
>  	return 1;
>  }
> @@ -703,5 +703,5 @@ void dhcpv6_init(const struct ctx *c)
>  	memcpy(resp_not_on_link.server_id.duid_lladdr,
>  	       c->our_tap_mac, sizeof(c->our_tap_mac));
>  
> -	resp.ia_addr.addr	= c->ip6.addr;
> +	resp.ia_addr.addr	= c->ip6.addrs[0].addr.a6;
>  }
> diff --git a/fwd.c b/fwd.c
> index 44a0e10..8d8151b 100644
> --- a/fwd.c
> +++ b/fwd.c
> @@ -516,7 +516,7 @@ static bool fwd_guest_accessible4(const struct ctx *c,
>  	/* For IPv4, addr_seen is initialised to addr, so is always a valid
>  	 * address
>  	 */
> -	if (IN4_ARE_ADDR_EQUAL(addr, &c->ip4.addr) ||
> +	if (IN4_ARE_ADDR_EQUAL(addr, inany_v4(&c->ip4.addrs[0].addr)) ||
>  	    IN4_ARE_ADDR_EQUAL(addr, &c->ip4.addr_seen))
>  		return false;
>  
> @@ -537,7 +537,7 @@ static bool fwd_guest_accessible6(const struct ctx *c,
>  	if (IN6_IS_ADDR_LOOPBACK(addr))
>  		return false;
>  
> -	if (IN6_ARE_ADDR_EQUAL(addr, &c->ip6.addr))
> +	if (IN6_ARE_ADDR_EQUAL(addr, &c->ip6.addrs[0].addr.a6))
>  		return false;
>  
>  	/* For IPv6, addr_seen starts unspecified, because we don't know what LL
> @@ -587,9 +587,9 @@ static void nat_outbound(const struct ctx *c, const union inany_addr *addr,
>  	else if (inany_equals6(addr, &c->ip6.map_host_loopback))
>  		*translated = inany_loopback6;
>  	else if (inany_equals4(addr, &c->ip4.map_guest_addr))
> -		*translated = inany_from_v4(c->ip4.addr);
> +		*translated = c->ip4.addrs[0].addr;
>  	else if (inany_equals6(addr, &c->ip6.map_guest_addr))
> -		translated->a6 = c->ip6.addr;
> +		translated->a6 = c->ip6.addrs[0].addr.a6;
>  	else
>  		*translated = *addr;
>  }
> @@ -710,10 +710,10 @@ bool nat_inbound(const struct ctx *c, const union inany_addr *addr,
>  		   inany_equals6(addr, &in6addr_loopback)) {
>  		translated->a6 = c->ip6.map_host_loopback;
>  	} else if (!IN4_IS_ADDR_UNSPECIFIED(&c->ip4.map_guest_addr) &&
> -		   inany_equals4(addr, &c->ip4.addr)) {
> +		   inany_equals(addr, &c->ip4.addrs[0].addr)) {
>  		*translated = inany_from_v4(c->ip4.map_guest_addr);
>  	} else if (!IN6_IS_ADDR_UNSPECIFIED(&c->ip6.map_guest_addr) &&
> -		   inany_equals6(addr, &c->ip6.addr)) {
> +		   inany_equals6(addr, &c->ip6.addrs[0].addr.a6)) {
>  		translated->a6 = c->ip6.map_guest_addr;
>  	} else if (fwd_guest_accessible(c, addr)) {
>  		*translated = *addr;
> diff --git a/inany.h b/inany.h
> index 36865f9..07bfc3d 100644
> --- a/inany.h
> +++ b/inany.h
> @@ -297,4 +297,20 @@ const char *inany_ntop(const union inany_addr *src, char *dst, socklen_t size);
>  int inany_pton(const char *src, union inany_addr *dst);
>  int inany_prefix_pton(const char *src, union inany_addr *dst, int *prefix_len);
>  
> +/* Flags for struct inany_addr_entry */
> +#define INANY_ADDR_CONFIGURED	(1 << 0)	/* User set via -a */
> +#define INANY_ADDR_HOST	(1 << 1)	/* From host interface */
> +
> +/**
> + * struct inany_addr_entry - Unified IPv4/IPv6 address entry
> + * @addr:		IPv4 (as mapped) or IPv6 address
> + * @prefix_len:	Prefix length (0-32 for IPv4, 0-128 for IPv6)

This should be 1-32 and 1-128, unless you find a way to make /0
assignments working (see my comment on 1/9).

> + * @flags:		INANY_ADDR_* flags
> + */
> +struct inany_addr_entry {
> +	union inany_addr	addr;
> +	uint16_t		prefix_len;
> +	uint16_t		flags;

Not that it really matters, but if you're trying to keep it small,
uint8_t is enough for both, and if you're trying to keep it simple,
'int' would be the right choice for 'prefix_len'.

> +};
> +
>  #endif /* INANY_H */
> diff --git a/ip.h b/ip.h
> index e5f5198..78bd43a 100644
> --- a/ip.h
> +++ b/ip.h
> @@ -135,6 +135,10 @@ static const struct in_addr in4addr_broadcast = { 0xffffffff };
>  #define IPV6_MIN_MTU		1280
>  #endif
>  
> +/* Maximum number of addresses per address family */
> +#define IP4_MAX_ADDRS		8
> +#define IP6_MAX_ADDRS		16
> +
>  int ip4_default_prefix_len(const struct in_addr *addr);
>  
>  #endif /* IP_H */
> diff --git a/ndp.c b/ndp.c
> index eb9e313..5248fd6 100644
> --- a/ndp.c
> +++ b/ndp.c
> @@ -257,7 +257,7 @@ static void ndp_ra(const struct ctx *c, const struct in6_addr *dst)
>  			.valid_lifetime		= ~0U,
>  			.pref_lifetime		= ~0U,
>  		},
> -		.prefix = c->ip6.addr,
> +		.prefix = c->ip6.addrs[0].addr.a6,
>  		.source_ll = {
>  			.header = {
>  				.type		= OPT_SRC_L2_ADDR,
> @@ -466,8 +466,8 @@ void ndp_send_init_req(const struct ctx *c)
>  			.icmp6_solicited	= 0, /* Reserved */
>  			.icmp6_override		= 0, /* Reserved */
>  		},
> -		.target_addr = c->ip6.addr
> +		.target_addr = c->ip6.addrs[0].addr.a6
>  	};
>  	debug("Sending initial NDP NS request for guest MAC address");
> -	ndp_send(c, &c->ip6.addr, &ns, sizeof(ns));
> +	ndp_send(c, &c->ip6.addrs[0].addr.a6, &ns, sizeof(ns));
>  }
> diff --git a/passt.h b/passt.h
> index 79d01dd..9c0c3fe 100644
> --- a/passt.h
> +++ b/passt.h
> @@ -66,9 +66,9 @@ enum passt_modes {
>  
>  /**
>   * struct ip4_ctx - IPv4 execution context
> - * @addr:		IPv4 address assigned to guest
> + * @addrs:		IPv4 addresses assigned to guest
> + * @addr_count:	Number of addresses in addrs[] array
>   * @addr_seen:		Latest IPv4 address seen as source from tap
> - * @prefixlen:		IPv4 prefix length (netmask)
>   * @guest_gw:		IPv4 gateway as seen by the guest
>   * @map_host_loopback:	Outbound connections to this address are NATted to the
>   *                      host's 127.0.0.1
> @@ -85,9 +85,10 @@ enum passt_modes {
>   */
>  struct ip4_ctx {
>  	/* PIF_TAP addresses */
> -	struct in_addr addr;
> +	struct inany_addr_entry addrs[IP4_MAX_ADDRS];
> +	int addr_count;
> +
>  	struct in_addr addr_seen;
> -	int prefix_len;
>  	struct in_addr guest_gw;
>  	struct in_addr map_host_loopback;
>  	struct in_addr map_guest_addr;
> @@ -107,7 +108,8 @@ struct ip4_ctx {
>  
>  /**
>   * struct ip6_ctx - IPv6 execution context
> - * @addr:		IPv6 address assigned to guest
> + * @addrs:		IPv6 addresses assigned to guest
> + * @addr_count:		Number of addresses in addrs[] array
>   * @addr_seen:		Latest IPv6 global/site address seen as source from tap
>   * @addr_ll_seen:	Latest IPv6 link-local address seen as source from tap
>   * @guest_gw:		IPv6 gateway as seen by the guest
> @@ -126,7 +128,9 @@ struct ip4_ctx {
>   */
>  struct ip6_ctx {
>  	/* PIF_TAP addresses */
> -	struct in6_addr addr;
> +	struct inany_addr_entry addrs[IP6_MAX_ADDRS];
> +	int addr_count;
> +
>  	struct in6_addr addr_seen;
>  	struct in6_addr addr_ll_seen;
>  	struct in6_addr guest_gw;
> diff --git a/pasta.c b/pasta.c
> index c307b8a..1bb3dd0 100644
> --- a/pasta.c
> +++ b/pasta.c
> @@ -340,8 +340,8 @@ void pasta_ns_conf(struct ctx *c)
>  			if (c->ip4.no_copy_addrs) {
>  				rc = nl_addr_set(nl_sock_ns, c->pasta_ifi,
>  						 AF_INET,
> -						 &c->ip4.addr,
> -						 c->ip4.prefix_len);
> +						 inany_v4(&c->ip4.addrs[0].addr),
> +						 c->ip4.addrs[0].prefix_len);
>  			} else {
>  				rc = nl_addr_dup(nl_sock, c->ifi4,
>  						 nl_sock_ns, c->pasta_ifi,
> @@ -387,10 +387,12 @@ void pasta_ns_conf(struct ctx *c)
>  					  0, IFF_NOARP);
>  
>  			if (c->ip6.no_copy_addrs) {
> -				if (!IN6_IS_ADDR_UNSPECIFIED(&c->ip6.addr)) {
> +				struct in6_addr *a = &c->ip6.addrs[0].addr.a6;
> +
> +				if (!IN6_IS_ADDR_UNSPECIFIED(a)) {
>  					rc = nl_addr_set(nl_sock_ns,
> -							 c->pasta_ifi, AF_INET6,
> -							 &c->ip6.addr, 64);
> +							 c->pasta_ifi,
> +							 AF_INET6, a, 64);
>  				}
>  			} else {
>  				rc = nl_addr_dup(nl_sock, c->ifi6,
> diff --git a/tap.c b/tap.c
> index 9d1344b..7c50013 100644
> --- a/tap.c
> +++ b/tap.c
> @@ -951,8 +951,8 @@ resume:
>  				c->ip6.addr_seen = *saddr;
>  			}
>  
> -			if (IN6_IS_ADDR_UNSPECIFIED(&c->ip6.addr))
> -				c->ip6.addr = *saddr;
> +			if (IN6_IS_ADDR_UNSPECIFIED(&c->ip6.addrs[0].addr.a6))
> +				c->ip6.addrs[0].addr.a6 = *saddr;
>  		} else if (!IN6_IS_ADDR_UNSPECIFIED(saddr)){
>  			c->ip6.addr_seen = *saddr;
>  		}

-- 
Stefano