Add new program to check prefix boundary

Using perl to check prefix boundary, is slow because of the overhead
of compiling the same script many times. So convert this simple task
to a C program.

1 files changed, 135 insertions, 0 deletions

diff --git a/src/check_prefix_boundary.c b/src/check_prefix_boundary.c
new file mode 100644
index 00000000..1c9ee30a
--- /dev/null
+++ b/src/check_prefix_boundary.c
@@ -0,0 +1,135 @@
+/*
+ * Check format of network prefix
+ */
+#include <stdio.h>
+#include <stdarg.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <arpa/inet.h>
+
+typedef struct
+{
+	uint8_t family;
+	uint8_t bytelen;
+	unsigned int plen;
+	uint32_t data[4];
+} inet_prefix;
+
+static void err(const char *fmt, ...)
+{
+	va_list ap;
+	
+	va_start(ap, fmt);
+	vfprintf(stderr, fmt, ap);
+	va_end(ap);
+
+	exit(1);
+}
+
+static void usage(void)
+{
+	fprintf(stderr, "Usage: check-prefix-boundary [-4|-6] address/prefix\n");
+	exit(1);
+}
+
+static void get_addr_1(inet_prefix *addr, const char *name, int family)
+{
+	memset(addr, 0, sizeof(*addr));
+
+	if (strchr(name, ':')) {
+		addr->family = AF_INET6;
+		addr->bytelen = 16;
+		if (family != AF_UNSPEC && family != AF_INET6)
+			err("IPV6 address not allowed\n");
+
+		if (inet_pton(AF_INET6, name, addr->data) <= 0)
+			err("Invalid IPV6 address: %s\n", name);
+
+		return;
+	}
+
+	addr->family = AF_INET;
+	addr->bytelen = 4;
+	if (family != AF_UNSPEC && family != AF_INET)
+		err("IPV4 address not allowed\n");
+
+	if (inet_pton(AF_INET, name, addr->data) <= 0)
+		err("Invalid IPV4 address: %s\n", name);
+	return;
+}
+
+static void get_prefix_1(inet_prefix *dst, char *arg, int family)
+{
+	char *slash, *endp;
+
+	memset(dst, 0, sizeof(*dst));
+
+	slash = strchr(arg, '/');
+	if (!slash || slash[1] == '\0')
+		err("Missing prefix length\n");
+	*slash = 0;
+
+	get_addr_1(dst, arg, family);
+
+	dst->plen = strtoul(slash+1, &endp, 0);
+	if (*endp != '\0')
+		err("Invalid character in prefix length\n");
+
+	if (dst->plen > 8 * dst->bytelen)
+		err("Prefix length is too large\n");
+
+	*slash = '/';
+}
+
+static void get_netmask(inet_prefix *msk, const inet_prefix *dst)
+{
+	int i, plen = dst->plen;
+
+	memset(msk, 0, sizeof(*msk));
+	msk->family = dst->family;
+	msk->bytelen = dst->bytelen;
+
+	for (i = 0; plen > 0 && i < dst->bytelen / sizeof(uint32_t); i++) {
+		uint32_t m = (plen > 32) ? ~0 : htonl(~0 << (32 - plen));
+		
+		msk->data[i] = dst->data[i] & m;
+		plen -= 32;
+	}
+}
+
+int main(int argc, char **argv)
+{
+	int family = AF_UNSPEC;
+
+	while (--argc) {
+		char *arg = *++argv;
+		inet_prefix dst, msk;
+
+		if (arg[0] == '-') 
+			switch(arg[1]) {
+			case '4':
+				family = AF_INET;
+				break;
+			case '6':
+				family = AF_INET6;
+				break;
+			default:
+				usage();
+			}
+
+		get_prefix_1(&dst, arg, family);
+		get_netmask(&msk, &dst);
+		
+		if (memcmp(msk.data, dst.data, dst.bytelen) != 0) {
+			char buf[INET_ADDRSTRLEN];
+			err("Prefix not on a natural network boundary."
+			    "Did you mean %s?\n", 
+			    inet_ntop(msk.family, msk.data, buf, sizeof buf));
+		}
+	}
+
+	return 0;
+}