db, IP2BIN: correct `format_ipv6()` output buffer sizes

`format_ipv6()` formats IPv6 addresses as hex-strings.  However, sizing for the
output buffer is not done quite right.

The elements of the `ipbin_array` array in ulogd_filter_IP2BIN.c are sized using
a local macro, `IPADDR_LENGTH`, which is defined as 128, the number of bits in
an IPv6 address; this is much larger than necessary.

Define an appropriate macro and use that instead.

Signed-off-by: Jeremy Sowden <jeremy@azazel.net>
Signed-off-by: Florian Westphal <fw@strlen.de>

1 files changed, 10 insertions, 1 deletions

diff --git a/include/ulogd/ulogd.h b/include/ulogd/ulogd.h
index 5eafb21..29082df 100644
--- a/include/ulogd/ulogd.h
+++ b/include/ulogd/ulogd.h
@@ -23,6 +23,15 @@
 
 #define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
 
+/*
+ * Minimum size of buffer required to hold an ipv6 address encoded as a
+ * hex-string, e.g.:
+ *
+ *                          ::1 -> "0x00000000000000000000000000000001"
+ * 2600:1408:ec00:36::1736:7f28 -> "0x26001408ec0000360000000017367f28"
+ */
+#define FORMAT_IPV6_BUFSZ (2 + sizeof(struct in6_addr) * 2 + 1)
+
 /* All types with MSB = 1 make use of value.ptr
  * other types use one of the union's member */
 
@@ -233,7 +242,7 @@ format_ipv6(char *buf, size_t size, const struct in6_addr *ipv6)
 {
 	unsigned i = 0;
 
-	if (size > 2 + sizeof (*ipv6) * 2) {
+	if (size >= FORMAT_IPV6_BUFSZ) {
 		buf[i++] = '0';
 		buf[i++] = 'x';