[PATCH v8 06/14] conf: Allow multiple -a/--address options per address family

[Jon Maloy <jmaloy@redhat.com>]

Allow specifying multiple addresses per family with -a/--address.
The first address of each family is used for DHCP/DHCPv6 assignment.

Link: https://bugs.passt.top/show_bug.cgi?id=47
Cc: lemmi@nerd2nerd.org
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.
v6: - Adapted to previous changes in series
    - Removed the "one address" limitation for -n option
v7: - Updated man page.
v8: - Adapted to previous changes in this series
    - Updated according to comments from David G.
---
 conf.c  |  7 ++++---
 passt.1 | 18 ++++++++----------
 pasta.c | 13 +++++++++----
 3 files changed, 21 insertions(+), 17 deletions(-)

diff --git a/conf.c b/conf.c
index 1c0c1786..8855a42e 100644
--- a/conf.c
+++ b/conf.c
@@ -595,9 +595,11 @@ 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 up to a maximum of %d times\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",
+		MAX_GUEST_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"
@@ -1596,7 +1598,6 @@ void conf(struct ctx *c, int argc, char **argv)
 			    IN6_IS_ADDR_V4COMPAT(&addr.a6))
 				die("Invalid address: %s", optarg);
 
-			/* Legacy behaviour: replace existing address if any */
 			fwd_set_addr(c, &addr, CONF_ADDR_USER, prefix_len);
 			if (inany_v4(&addr))
 				c->ip4.no_copy_addrs = true;
diff --git a/passt.1 b/passt.1
index 908fd4a4..254bd80e 100644
--- a/passt.1
+++ b/passt.1
@@ -169,16 +169,14 @@ An optional /\fIprefix_len\fR (0-32 for IPv4, 0-128 for IPv6) can be
 appended in CIDR notation (e.g. 192.0.2.1/24). This is an alternative to
 using the \fB-n\fR, \fB--netmask\fR option. Mixing CIDR notation with
 \fB-n\fR results in an error.
-If a prefix length is assigned to an IPv6 address using this method, it will
-in the current code version be overridden by the default value of 64.
-This option can be specified zero (for defaults) to two times (once for IPv4,
-once for IPv6).
-By default, assigned IPv4 and IPv6 addresses are taken from the host interfaces
-with the first default route, if any, for the corresponding IP version. If no
-default routes are available and there is any interface with any route for a
-given IP version, the first of these interfaces will be chosen instead. If no
-such interface exists for a given IP version, the link-local address 169.254.2.1
-is assigned for IPv4, and no additional address will be assigned for IPv6.
+This option can be given multiple times, indicating multiple different
+addresses. By default, assigned IPv4 and IPv6 addresses are taken from
+the host interfaces with the first default route, if any, for the
+corresponding IP version. If no default routes are available and there
+is any interface with any route for a given IP version, the first of
+these interfaces will be chosen instead. If no such interface exists for
+a given IP version, the link-local address 169.254.2.1 is assigned for
+IPv4, and no additional address will be assigned for IPv6.
 
 .TP
 .BR \-n ", " \-\-netmask " " \fImask
diff --git a/pasta.c b/pasta.c
index 9ef3ac00..aea52001 100644
--- a/pasta.c
+++ b/pasta.c
@@ -343,8 +343,9 @@ void pasta_ns_conf(struct ctx *c)
 
 		if (c->ifi4) {
 			if (c->ip4.no_copy_addrs) {
-				a = fwd_get_addr(c, AF_INET, CONF_ADDR_ANY, 0);
-				if (a) {
+				int ac = c->addr_count;
+
+				for_each_addr(a, c->addrs, ac, AF_INET) {
 					const struct in_addr *v4;
 
 					v4 = inany_prefix_v4(&a->addr,
@@ -353,6 +354,8 @@ void pasta_ns_conf(struct ctx *c)
 					rc = nl_addr_set(nl_sock_ns,
 							 c->pasta_ifi, AF_INET,
 							 v4, plen);
+					if (rc < 0)
+						break;
 				}
 			} else {
 				rc = nl_addr_dup(nl_sock, c->ifi4,
@@ -406,12 +409,14 @@ ipv4_done:
 					  0, IFF_NOARP);
 
 			if (c->ip6.no_copy_addrs) {
-				a = fwd_get_addr(c, AF_INET6, CONF_ADDR_ANY, 0);
-				if (a)
+				for_each_addr(a, c->addrs, c->addr_count, AF_INET6) {
 					rc = nl_addr_set(nl_sock_ns,
 							 c->pasta_ifi,
 							 AF_INET6, &a->addr.a6,
 							 a->prefix_len);
+					if (rc < 0)
+						break;
+				}
 			} else {
 				rc = nl_addr_dup(nl_sock, c->ifi6,
 						 nl_sock_ns, c->pasta_ifi,
-- 
2.52.0