iptables: handle cidr notation more sanely (Phil Oester <kernel@linuxace.com>)

At present, a command such as

iptables -A foo -s 10.10/16

will interpret 10.10/16 as 10.0.0.10/16, and after applying the mask end
up with 10.0.0.0/16, which likely isn't what the user intended.  Yet
some people do expect 10.10 (without the cidr notation) to end up as
10.0.0.10.

The below patch should satisfy all parties.  It zero pads the missing
octets only in the cidr case, leaving the IP untouched otherwise.

This resolves bug #422

diff --git a/iptables.c b/iptables.c
index ea0eae361ba47026875a1fed9e63562e37db7406..781498628484c93e61140b83c016f4c4f696d6ab 100644 (file)
--- a/iptables.c
+++ b/iptables.c
@@ -583,6 +583,34 @@ addr_to_host(const struct in_addr *addr)
        return (char *) NULL;
 }
 
+static void 
+pad_cidr(char *cidr)
+{
+       char *p, *q;
+       unsigned int onebyte;
+       int i, j;
+       char buf[20];
+
+       /* copy dotted string, because we need to modify it */
+       strncpy(buf, cidr, sizeof(buf) - 1);
+       buf[sizeof(buf) - 1] = '\0';
+
+       p = buf;
+       for (i = 0; i <= 3; i++) {
+               if ((q = strchr(p, '.')) == NULL)
+                       break;
+               *q = '\0';
+               if (string_to_number(p, 0, 255, &onebyte) == -1)
+                       return;
+               p = q + 1;
+       }
+
+       /* pad remaining octets with zeros */
+       for (j = i; j < 3; j++) {
+               strcat(cidr, ".0");
+       }
+}
+
 /*
  *     All functions starting with "parse" should succeed, otherwise
  *     the program fails.
@@ -651,6 +679,8 @@ parse_hostnetworkmask(const char *name, struct in_addr **addrpp,
        if ((p = strrchr(buf, '/')) != NULL) {
                *p = '\0';
                addrp = parse_mask(p + 1);
+               if (strrchr(p + 1, '.') == NULL)
+                       pad_cidr(buf);
        } else
                addrp = parse_mask(NULL);
        inaddrcpy(maskp, addrp);