* [PATCH] conf: Support CIDR notation for -a/--address option
@ 2025-12-16 23:04 Jon Maloy
2025-12-17 8:50 ` Laurent Vivier
0 siblings, 1 reply; 2+ messages in thread
From: Jon Maloy @ 2025-12-16 23:04 UTC (permalink / raw)
To: sbrivio, dgibson, david, jmaloy, passt-dev
We 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.
For IPv4, the prefix is stored in ip4.prefix_len when provided. The
CIDR prefix and -n/--netmask options are mutually exclusive - using
both results in an error.
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 <jmaloy@redhat.com>
---
conf.c | 99 +++++++++++++++++++++++++++++++++++++++++++++++++---------
1 file changed, 84 insertions(+), 15 deletions(-)
diff --git a/conf.c b/conf.c
index 2942c8c..0f66c77 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"
@@ -1501,6 +1551,7 @@ void conf(struct ctx *c, int argc, char **argv)
bool copy_addrs_opt = false, copy_routes_opt = false;
enum fwd_ports_mode fwd_default = FWD_NONE;
bool v4_only = false, v6_only = false;
+ bool prefix_explicit = false;
unsigned dns4_idx = 0, dns6_idx = 0;
unsigned long max_mtu = IP_MAX_MTU;
struct fqdn *dnss = c->dns_search;
@@ -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_explicit)
+ die("Can't use both -n and CIDR prefix");
+ c->ip4.prefix_len = prefix;
+ prefix_explicit = 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_explicit)
+ 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_explicit = true;
break;
case 'M':
parse_mac(c->our_tap_mac, optarg);
--
2.52.0
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH] conf: Support CIDR notation for -a/--address option
2025-12-16 23:04 [PATCH] conf: Support CIDR notation for -a/--address option Jon Maloy
@ 2025-12-17 8:50 ` Laurent Vivier
0 siblings, 0 replies; 2+ messages in thread
From: Laurent Vivier @ 2025-12-17 8:50 UTC (permalink / raw)
To: Jon Maloy, sbrivio, dgibson, david, passt-dev
On 12/17/25 00:04, Jon Maloy wrote:
> We 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.
>
> For IPv4, the prefix is stored in ip4.prefix_len when provided. The
> CIDR prefix and -n/--netmask options are mutually exclusive - using
> both results in an error.
>
> 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 <jmaloy@redhat.com>
> ---
> conf.c | 99 +++++++++++++++++++++++++++++++++++++++++++++++++---------
> 1 file changed, 84 insertions(+), 15 deletions(-)
Reviewed-by: Laurent Vivier <lvivier@redhat.com>
Note if you provide two IPv4 addresses with prefix (-a XXX/YY -a XXX/YY) the error
reported will be "Can't use both -n and CIDR prefix" that is not the correct error.
Thanks,
Laurent>
> diff --git a/conf.c b/conf.c
> index 2942c8c..0f66c77 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"
> @@ -1501,6 +1551,7 @@ void conf(struct ctx *c, int argc, char **argv)
> bool copy_addrs_opt = false, copy_routes_opt = false;
> enum fwd_ports_mode fwd_default = FWD_NONE;
> bool v4_only = false, v6_only = false;
> + bool prefix_explicit = false;
> unsigned dns4_idx = 0, dns6_idx = 0;
> unsigned long max_mtu = IP_MAX_MTU;
> struct fqdn *dnss = c->dns_search;
> @@ -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_explicit)
> + die("Can't use both -n and CIDR prefix");
> + c->ip4.prefix_len = prefix;
> + prefix_explicit = 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_explicit)
> + 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_explicit = true;
> break;
> case 'M':
> parse_mac(c->our_tap_mac, optarg);
^ permalink raw reply [flat|nested] 2+ messages in thread
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