From: Joseph C. Lehner <joseph.c.lehner@gmail.com>
Date: Sat, 19 Nov 2016 12:02:29 +0000 (+0100)
Subject: Check subnet mask's sanity
X-Git-Tag: v0.9.9~3
X-Git-Url: https://git.librecmc.org/?a=commitdiff_plain;h=eda1a2a69882c1d53936aada626820260709406a;p=oweals%2Fnmrpflash.git

Check subnet mask's sanity
---

diff --git a/nmrp.c b/nmrp.c
index da665cf..c1bfb9c 100644
--- a/nmrp.c
+++ b/nmrp.c
@@ -430,7 +430,9 @@ int nmrp_do(struct nmrpd_args *args)
 		return 1;
 	}
 
-	if ((ipconf.mask.s_addr = inet_addr(args->ipmask)) == INADDR_NONE) {
+	ipconf.mask.s_addr = inet_addr(args->ipmask);
+	if (ipconf.mask.s_addr == INADDR_NONE
+			|| netmask(bitcount(ipconf.mask.s_addr)) != ipconf.mask.s_addr) {
 		fprintf(stderr, "Invalid subnet mask '%s'.\n", args->ipmask);
 		return 1;
 	}
diff --git a/nmrpd.h b/nmrpd.h
index e061155..af9699a 100644
--- a/nmrpd.h
+++ b/nmrpd.h
@@ -133,4 +133,6 @@ int ethsock_ip_del(struct ethsock *sock, struct ethsock_ip_undo **undo);
 
 time_t time_monotonic();
 char *lltostr(long long ll, int base);
+uint32_t bitcount(uint32_t n);
+uint32_t netmask(uint32_t count);
 #endif
diff --git a/util.c b/util.c
index 4422442..a1b2c52 100644
--- a/util.c
+++ b/util.c
@@ -35,3 +35,17 @@ char *lltostr(long long ll, int base)
 	snprintf(buf, sizeof(buf) - 1, (base == 16 ? "%llx" : (base == 8 ? "%llo" : "%lld")), ll);
 	return buf;
 }
+
+uint32_t bitcount(uint32_t n)
+{
+	uint32_t c;
+	for (c = 0; n; ++c) {
+		n &= n - 1;
+	}
+	return c;
+}
+
+uint32_t netmask(uint32_t count)
+{
+	return htonl(count <= 32 ? 0xffffffff << (32 - count) : 0);
+}