Add -W, --whitelist addr/cidr

This only allows packets from the addresses listed and overrides
blacklist if set.

5 files changed, 54 insertions, 4 deletions

diff --git a/dhcpcd.8.in b/dhcpcd.8.in
index 059a35a9..7e712456 100644
--- a/dhcpcd.8.in
+++ b/dhcpcd.8.in
@@ -22,7 +22,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd April 24, 2009
+.Dd July 5, 2009
 .Dt DHCPCD 8 SMM
 .Os
 .Sh NAME
@@ -51,6 +51,7 @@
 .Op Fl O , -nooption Ar option
 .Op Fl Q , -require Ar option
 .Op Fl S , -static Ar value
+.Op Fl W , -whitelist Ar address Ns Op Ar /cidr
 .Op Fl X , -blacklist Ar address Ns Op Ar /cidr
 .Op Fl Z , -denyinterfaces Ar pattern
 .Op interface
@@ -465,6 +466,13 @@ Display a list of option codes and the associated variable for use in
 Variables are prefixed with new_ and old_ unless the option number is -.
 Variables without an option are part of the DHCP message and cannot be
 directly requested.
+.It Fl W, -whitelist Ar address Ns Op /cidr
+Only accept packets from
+.Ar address Ns Op /cidr .
+.Fl X, -blacklist
+is ignored if
+.Fl W, -whitelist
+is set.
 .It Fl X, -blacklist Ar address Ns Op Ar /cidr
 Ignore all packets from
 .Ar address Ns Op Ar /cidr .
diff --git a/dhcpcd.c b/dhcpcd.c
index 1b4dd9ae..950dd169 100644
--- a/dhcpcd.c
+++ b/dhcpcd.c
@@ -430,6 +430,19 @@ blacklisted_ip(const struct if_options *ifo, in_addr_t addr)
 	return 0;
 }
 
+static int
+whitelisted_ip(const struct if_options *ifo, in_addr_t addr)
+{
+	size_t i;
+
+	if (ifo->whitelist_len == 0)
+		return -1;
+	for (i = 0; i < ifo->whitelist_len; i += 2)
+		if (ifo->whitelist[i] == (addr & ifo->whitelist[i + 1]))
+			return 1;
+	return 0;
+}
+
 static void
 handle_dhcp(struct interface *iface, struct dhcp_message **dhcpp)
 {
@@ -585,6 +598,7 @@ handle_dhcp_packet(void *arg)
 	const uint8_t *pp;
 	ssize_t bytes;
 	struct in_addr from;
+	int i;
 
 	/* We loop through until our buffer is empty.
 	 * The benefit is that if we get >1 DHCP packet in our buffer and
@@ -600,7 +614,15 @@ handle_dhcp_packet(void *arg)
 			    iface->name, inet_ntoa(from));
 			continue;
 		}
-		if (blacklisted_ip(iface->state->options, from.s_addr)) {
+		i = whitelisted_ip(iface->state->options, from.s_addr);
+		if (i == 0) {
+			syslog(LOG_WARNING,
+			    "%s: non whitelisted DHCP packet from %s",
+			    iface->name, inet_ntoa(from));
+			continue;
+		} else if (i != 1 &&
+		    blacklisted_ip(iface->state->options, from.s_addr) == 1)
+		{
 			syslog(LOG_WARNING,
 			    "%s: blacklisted DHCP packet from %s",
 			    iface->name, inet_ntoa(from));
diff --git a/dhcpcd.conf.5.in b/dhcpcd.conf.5.in
index 689a90d5..c9efad72 100644
--- a/dhcpcd.conf.5.in
+++ b/dhcpcd.conf.5.in
@@ -22,7 +22,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd July 4, 2009
+.Dd July 5, 2009
 .Dt DHCPCD.CONF 5 SMM
 .Os
 .Sh NAME
@@ -76,6 +76,13 @@ carrier status.
 .It Ic blacklist Ar address Ns Op /cidr
 Ignores all packets from
 .Ar address Ns Op /cidr .
+.It Ic whitelist Ar address Ns Op /cidr
+Only accept packets from
+.Ar address Ns Op /cidr .
+.Ic blacklist
+is ignored if
+.Ic whitelist
+is set.
 .It Ic clientid Ar string
 Send the
 .Ar clientid .
diff --git a/if-options.c b/if-options.c
index 7a9e5e3d..a22929b3 100644
--- a/if-options.c
+++ b/if-options.c
@@ -90,6 +90,7 @@ const struct option cf_options[] = {
 	{"static",          required_argument, NULL, 'S'},
 	{"test",            no_argument,       NULL, 'T'},
 	{"variables",       no_argument,       NULL, 'V'},
+	{"whitelist",       required_argument, NULL, 'W'},
 	{"blacklist",       required_argument, NULL, 'X'},
 	{"denyinterfaces",  required_argument, NULL, 'Z'},
 	{"arping",          required_argument, NULL, O_ARPING},
@@ -653,6 +654,16 @@ parse_option(struct if_options *ifo, int opt, const char *arg)
 			ifo->config[s + 1] = NULL;
 		}
 		break;
+	case 'W':
+		if (parse_addr(&addr, &addr2, arg) != 0)
+			return -1;
+		if (strchr(arg, '/') == NULL)
+			addr2.s_addr = INADDR_BROADCAST;
+		ifo->whitelist = xrealloc(ifo->whitelist,
+		    sizeof(in_addr_t) * (ifo->whitelist_len + 2));
+		ifo->whitelist[ifo->whitelist_len++] = addr.s_addr;
+		ifo->whitelist[ifo->whitelist_len++] = addr2.s_addr;
+		break;
 	case 'X':
 		if (parse_addr(&addr, &addr2, arg) != 0)
 			return -1;
diff --git a/if-options.h b/if-options.h
index 396f44ea..3fa86396 100644
--- a/if-options.h
+++ b/if-options.h
@@ -37,7 +37,7 @@
 
 /* Don't set any optional arguments here so we retain POSIX
  * compatibility with getopt */
-#define IF_OPTS "bc:def:h:i:kl:m:no:pqr:s:t:u:v:xy:z:ABC:DEF:GI:KLN:O:Q:TVX:Z:"
+#define IF_OPTS "bc:def:h:i:kl:m:no:pqr:s:t:u:v:xy:z:ABC:DEF:GI:KLN:O:Q:TVW:X:Z:"
 
 #define DEFAULT_TIMEOUT		30
 #define DEFAULT_REBOOT		10
@@ -100,6 +100,8 @@ struct if_options {
 
 	size_t blacklist_len;
 	in_addr_t *blacklist;
+	size_t whitelist_len;
+	in_addr_t *whitelist;
 	size_t arping_len;
 	in_addr_t *arping;
 	char *fallback;