[PATCH v3 07/11] conf: Allow multiple -a/--address options per address family

[Jon Maloy <jmaloy@redhat.com>]

We enable configuration of multiple IPv4 and IPv6 addresses by allowing
repeated use of the -a/--address option.

- We update option parsing to append addresses to the unified addrs[]
  array, with limit checks for IP4_MAX_ADDRS and IP6_MAX_ADDRS.
- Each address specified via -a, but with no prefix length indicated,
  gets a class-based default prefix length.
- If no -a option is given, addresses/prefix lengths are inherited from
  the template interface.
- If a prefix length is to be added, it has to be done in CIDR format,
  except for the very first address.
- We configure all indicated addresses in the namespace interface using
  the for_each_addr() macro.

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.
---
 conf.c  | 23 ++++++++++++++++-------
 pasta.c | 21 ++++++++++++++-------
 2 files changed, 30 insertions(+), 14 deletions(-)

diff --git a/conf.c b/conf.c
index bb6bcf8..d73a3dd 100644
--- a/conf.c
+++ b/conf.c
@@ -803,13 +803,13 @@ static unsigned int conf_ip6(unsigned int ifi, struct ctx *c)
 	}
 
 	e = first_v6(c);
-	c->ip6.addr_seen = e->addr.a6;
+	if (e)
+		c->ip6.addr_seen = e->addr.a6;
 
 	if (IN6_IS_ADDR_LINKLOCAL(&c->ip6.guest_gw))
 		c->ip6.our_tap_ll = c->ip6.guest_gw;
 
-	if (IN6_IS_ADDR_UNSPECIFIED(&e->addr.a6) ||
-	    IN6_IS_ADDR_UNSPECIFIED(&c->ip6.our_tap_ll))
+	if (!count_v6(c) || IN6_IS_ADDR_UNSPECIFIED(&c->ip6.our_tap_ll))
 		return 0;
 
 	return ifi;
@@ -901,9 +901,11 @@ 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 multiple times (limit: %d IPv4, %d IPv6)\n"
 		"    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",
+		IP4_MAX_ADDRS, IP6_MAX_ADDRS);
+	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"
@@ -1836,6 +1838,9 @@ void conf(struct ctx *c, int argc, char **argv)
 				die("Can't mix CIDR with -n");
 
 			if (af == AF_INET) {
+				if (count_v4(c) >= IP4_MAX_ADDRS)
+					die("Too many IPv4 addresses");
+
 				e = &c->addrs[c->addr_count];
 				e->addr = addr;
 				e->prefix_len = prefix_len ? prefix_len :
@@ -1845,6 +1850,9 @@ void conf(struct ctx *c, int argc, char **argv)
 				if (c->mode == MODE_PASTA)
 					c->ip4.no_copy_addrs = true;
 			} else if (af == AF_INET6) {
+				if (count_v6(c) >= IP6_MAX_ADDRS)
+					die("Too many IPv6 addresses");
+
 				e = &c->addrs[c->addr_count];
 				e->addr = addr;
 				e->prefix_len = prefix_len ? prefix_len : 64;
@@ -1861,6 +1869,8 @@ void conf(struct ctx *c, int argc, char **argv)
 			struct inany_addr_entry *e;
 			int plen;
 
+			if (count_v4(c) > 1)
+				die("-n can only be used with first address");
 			if (prefix_from_cidr)
 				die("Can't use both -n and CIDR prefix length");
 			plen = conf_ip4_prefix(optarg);
@@ -2156,8 +2166,7 @@ void conf(struct ctx *c, int argc, char **argv)
 	if (!c->ifi6) {
 		c->no_ndp = 1;
 		c->no_dhcpv6 = 1;
-	} else if (!first_v6(c) ||
-		   IN6_IS_ADDR_UNSPECIFIED(&first_v6(c)->addr.a6)) {
+	} else if (!count_v6(c)) {
 		c->no_dhcpv6 = 1;
 	}
 
diff --git a/pasta.c b/pasta.c
index de0ba14..8cb5873 100644
--- a/pasta.c
+++ b/pasta.c
@@ -312,10 +312,14 @@ static void pasta_ns_conf_ip4(struct ctx *c)
 	int rc = 0;
 
 	if (c->ip4.no_copy_addrs) {
-		struct inany_addr_entry *e = first_v4(c);
+		const struct inany_addr_entry *e;
 
-		rc = nl_addr_set(nl_sock_ns, c->pasta_ifi, AF_INET,
-				 inany_v4(&e->addr), e->prefix_len - 96);
+		for_each_addr(c, e, AF_INET) {
+			rc = nl_addr_set(nl_sock_ns, c->pasta_ifi, AF_INET,
+					 inany_v4(&e->addr), e->prefix_len - 96);
+			if (rc < 0)
+				break;
+		}
 	} else {
 		rc = nl_addr_dup(nl_sock, c->ifi4,
 				 nl_sock_ns, c->pasta_ifi, AF_INET);
@@ -346,7 +350,6 @@ static void pasta_ns_conf_ip4(struct ctx *c)
  */
 static void pasta_ns_conf_ip6(struct ctx *c)
 {
-	struct inany_addr_entry *e;
 	int rc = 0;
 
 	rc = nl_addr_get_ll(nl_sock_ns, c->pasta_ifi, &c->ip6.addr_ll_seen);
@@ -365,11 +368,15 @@ static void pasta_ns_conf_ip6(struct ctx *c)
 	nl_link_set_flags(nl_sock_ns, c->pasta_ifi, 0, IFF_NOARP);
 
 	if (c->ip6.no_copy_addrs) {
-		e = first_v6(c);
+		const struct inany_addr_entry *e;
 
-		if (e && !IN6_IS_ADDR_UNSPECIFIED(&e->addr.a6)) {
+		for_each_addr(c, e, AF_INET6) {
+			if (IN6_IS_ADDR_UNSPECIFIED(&e->addr.a6))
+				continue;
 			rc = nl_addr_set(nl_sock_ns, c->pasta_ifi,
-					 AF_INET6, &e->addr.a6, 64);
+					 AF_INET6, &e->addr.a6, e->prefix_len);
+			if (rc < 0)
+				break;
 		}
 	} else {
 		rc = nl_addr_dup(nl_sock, c->ifi6,
-- 
2.52.0