Extend the -a/--address option to accept addresses in CIDR notation
(e.g., 192.168.1.1/24 or 2001:db8::1/64) as an alternative to using
separate -a and -n options.
Add conf_addr_prefix() helper function that:
- Parses address strings with optional /prefix suffix
- Validates prefix length based on address family (0-32 for IPv4,
0-128 for IPv6)
- Returns address family and fills address/prefix output parameters
For IPv4, the prefix is stored in ip4.prefix_len when provided.
Multiple CIDR addresses use last-wins semantics for the prefix,
consistent with how addresses are handled currently. However,
mixing -n and CIDR notation results in an error to catch likely
user mistakes.
Also fix a bug in conf_ip4_prefix() that was incorrectly using the
global 'optarg' instead of its 'arg' parameter.
Signed-off-by: Jon Maloy
---
v2: Fixed incorrect error printout, as noted by Laurent Vivier.
We now keep the old semantics, i.e., allowing multiple -a
options for each protocol. This semantics looks wrong,
but will anyway be fixed in my upcoming series.
Signed-off-by: Jon Maloy
---
conf.c | 99 +++++++++++++++++++++++++++++++++++++++++++++++++---------
1 file changed, 84 insertions(+), 15 deletions(-)
diff --git a/conf.c b/conf.c
index 2942c8c..764b910 100644
--- a/conf.c
+++ b/conf.c
@@ -682,7 +682,7 @@ static int conf_ip4_prefix(const char *arg)
return -1;
} else {
errno = 0;
- len = strtoul(optarg, NULL, 0);
+ len = strtoul(arg, NULL, 0);
if (len > 32 || errno)
return -1;
}
@@ -690,6 +690,56 @@ static int conf_ip4_prefix(const char *arg)
return len;
}
+/**
+ * conf_addr_prefix() - Parse address with optional /prefix notation
+ * @arg: Address string, optionally with /prefix
+ * @addr4: Output for IPv4 address
+ * @addr6: Output for IPv6 address
+ * @prefix: Output for prefix length (0 if not specified)
+ *
+ * Return: AF_INET for IPv4, AF_INET6 for IPv6, -1 on error
+ */
+static int conf_addr_prefix(const char *arg, struct in_addr *addr4,
+ struct in6_addr *addr6, int *prefix)
+{
+ char buf[INET6_ADDRSTRLEN + sizeof("/128")];
+ char *slash;
+
+ *prefix = 0;
+
+ if (snprintf(buf, sizeof(buf), "%s", arg) >= (int)sizeof(buf))
+ return -1;
+
+ /* Check for /prefix suffix */
+ slash = strchr(buf, '/');
+ if (slash) {
+ unsigned long len;
+ char *end;
+
+ *slash = '\0';
+ errno = 0;
+ len = strtoul(slash + 1, &end, 10);
+ if (errno || *end)
+ return -1;
+
+ *prefix = len;
+ }
+
+ if (inet_pton(AF_INET6, buf, addr6) == 1) {
+ if (*prefix > 128)
+ return -1;
+ return AF_INET6;
+ }
+
+ if (inet_pton(AF_INET, buf, addr4) == 1) {
+ if (*prefix > 32)
+ return -1;
+ return AF_INET;
+ }
+
+ return -1;
+}
+
/**
* conf_ip4() - Verify or detect IPv4 support, get relevant addresses
* @ifi: Host interface to attempt (0 to determine one)
@@ -896,7 +946,7 @@ static void usage(const char *name, FILE *f, int status)
" a zero value disables assignment\n"
" 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\n"
+ " -a, --address ADDR Assign IPv4 or IPv6 address ADDR[/PREFIX]\n"
" can be specified zero to two times (for IPv4 and IPv6)\n"
" default: use addresses from interface with default route\n"
" -n, --netmask MASK Assign IPv4 MASK, dot-decimal or bits\n"
@@ -1499,6 +1549,7 @@ void conf(struct ctx *c, int argc, char **argv)
const char *logname = (c->mode == MODE_PASTA) ? "pasta" : "passt";
char userns[PATH_MAX] = { 0 }, netns[PATH_MAX] = { 0 };
bool copy_addrs_opt = false, copy_routes_opt = false;
+ bool prefix_from_cidr = false, prefix_from_opt = false;
enum fwd_ports_mode fwd_default = FWD_NONE;
bool v4_only = false, v6_only = false;
unsigned dns4_idx = 0, dns6_idx = 0;
@@ -1808,23 +1859,38 @@ void conf(struct ctx *c, int argc, char **argv)
c->mtu = mtu;
break;
}
- case 'a':
- if (inet_pton(AF_INET6, optarg, &c->ip6.addr) &&
- !IN6_IS_ADDR_UNSPECIFIED(&c->ip6.addr) &&
- !IN6_IS_ADDR_LOOPBACK(&c->ip6.addr) &&
- !IN6_IS_ADDR_V4MAPPED(&c->ip6.addr) &&
- !IN6_IS_ADDR_V4COMPAT(&c->ip6.addr) &&
- !IN6_IS_ADDR_MULTICAST(&c->ip6.addr)) {
+ case 'a': {
+ struct in6_addr addr6;
+ struct in_addr addr4;
+ int prefix = 0;
+ int af;
+
+ af = conf_addr_prefix(optarg, &addr4, &addr6, &prefix);
+
+ if (af == AF_INET6 &&
+ !IN6_IS_ADDR_UNSPECIFIED(&addr6) &&
+ !IN6_IS_ADDR_LOOPBACK(&addr6) &&
+ !IN6_IS_ADDR_V4MAPPED(&addr6) &&
+ !IN6_IS_ADDR_V4COMPAT(&addr6) &&
+ !IN6_IS_ADDR_MULTICAST(&addr6)) {
+ c->ip6.addr = addr6;
if (c->mode == MODE_PASTA)
c->ip6.no_copy_addrs = true;
break;
}
- if (inet_pton(AF_INET, optarg, &c->ip4.addr) &&
- !IN4_IS_ADDR_UNSPECIFIED(&c->ip4.addr) &&
- !IN4_IS_ADDR_BROADCAST(&c->ip4.addr) &&
- !IN4_IS_ADDR_LOOPBACK(&c->ip4.addr) &&
- !IN4_IS_ADDR_MULTICAST(&c->ip4.addr)) {
+ if (af == AF_INET &&
+ !IN4_IS_ADDR_UNSPECIFIED(&addr4) &&
+ !IN4_IS_ADDR_BROADCAST(&addr4) &&
+ !IN4_IS_ADDR_LOOPBACK(&addr4) &&
+ !IN4_IS_ADDR_MULTICAST(&addr4)) {
+ c->ip4.addr = addr4;
+ if (prefix) {
+ if (prefix_from_opt)
+ die("Can't use both -n and CIDR prefix");
+ c->ip4.prefix_len = prefix;
+ prefix_from_cidr = true;
+ }
if (c->mode == MODE_PASTA)
c->ip4.no_copy_addrs = true;
break;
@@ -1832,11 +1898,14 @@ void conf(struct ctx *c, int argc, char **argv)
die("Invalid address: %s", optarg);
break;
+ }
case 'n':
+ if (prefix_from_cidr)
+ die("Can't use both -n and CIDR prefix");
c->ip4.prefix_len = conf_ip4_prefix(optarg);
if (c->ip4.prefix_len < 0)
die("Invalid netmask: %s", optarg);
-
+ prefix_from_opt = true;
break;
case 'M':
parse_mac(c->our_tap_mac, optarg);
--
2.52.0