[PATCH xtables-addons v2 3/3] xt_geoip: fix in6_addr little-endian byte-swapping.

[Jeremy Sowden <jeremy@azazel.net>]

The Perl script that builds the GeoIP DB's uses inet_pton(3) to convert
the addresses to network byte-order.  This swaps 32-bit segments and
converts:

  1234:5678::90ab:cdef

to:

  8765:4321::fedc:ba09

The kernel module compares the addresses in packets with the ranges from
the DB in host byte-order using binary search.  It uses 32-bit swaps
when converting the addresses.

libxt_geoip, however, which the module uses to load the ranges from the
DB and convert them from NBO to HBO, uses 16-bit swaps to do so, and
this means that:

  1234:5678::90ab:cdef

becomes:

  4321:8765::ba09:fedc

Obviously, this is inconsistent with the kernel-module and DB build-
script and breaks the binary search.

Fixes: b91dbd03c717 ("geoip: store database in network byte order")
Reported-by: "Thomas B. Clark" <kernel@clark.bz>
Signed-off-by: Jeremy Sowden <jeremy@azazel.net>
---
 extensions/libxt_geoip.c | 28 ++++++++--------------------
 1 file changed, 8 insertions(+), 20 deletions(-)

diff --git a/extensions/libxt_geoip.c b/extensions/libxt_geoip.c
index 116f5f86eb01..5b8697dc6161 100644
--- a/extensions/libxt_geoip.c
+++ b/extensions/libxt_geoip.c
@@ -50,26 +50,6 @@ static struct option geoip_opts[] = {
 };
 
 #if __BYTE_ORDER == __LITTLE_ENDIAN
-static void geoip_swap_le16(uint16_t *buf)
-{
-	unsigned char *p = (void *)buf;
-	uint16_t n= p[0] + (p[1] << 8);
-	p[0] = (n >> 8) & 0xff;
-	p[1] = n & 0xff;
-}
-
-static void geoip_swap_in6(struct in6_addr *in6)
-{
-	geoip_swap_le16(&in6->s6_addr16[0]);
-	geoip_swap_le16(&in6->s6_addr16[1]);
-	geoip_swap_le16(&in6->s6_addr16[2]);
-	geoip_swap_le16(&in6->s6_addr16[3]);
-	geoip_swap_le16(&in6->s6_addr16[4]);
-	geoip_swap_le16(&in6->s6_addr16[5]);
-	geoip_swap_le16(&in6->s6_addr16[6]);
-	geoip_swap_le16(&in6->s6_addr16[7]);
-}
-
 static void geoip_swap_le32(uint32_t *buf)
 {
 	unsigned char *p = (void *)buf;
@@ -79,6 +59,14 @@ static void geoip_swap_le32(uint32_t *buf)
 	p[2] = (n >> 8) & 0xff;
 	p[3] = n & 0xff;
 }
+
+static void geoip_swap_in6(struct in6_addr *in6)
+{
+	geoip_swap_le32(&in6->s6_addr32[0]);
+	geoip_swap_le32(&in6->s6_addr32[1]);
+	geoip_swap_le32(&in6->s6_addr32[2]);
+	geoip_swap_le32(&in6->s6_addr32[3]);
+}
 #endif
 
 static void *
-- 
2.24.0