arptables-nft: fix decoding of hlen on bigendian platforms

The existing test fail with:
extensions/libarpt_standard.t: ERROR: line 2 (cannot find: arptables -I INPUT -s 192.168.0.1)

... because hlen is 0 instead of expected "6".
The rule is correct, i.e. this is a decode/display bug: arp_hlen is
specified as 'unsigned short' instead of uint8_t.

On LSB systems, this doesn't matter but on MSB the value then is '0x600'
instead of '0x006' which becomes 0 when assignment to the u8 header field.

Signed-off-by: Florian Westphal <fw@strlen.de>
Acked-by: Phil Sutter <phil@nwl.cc>

diff --git a/iptables/nft-arp.c b/iptables/nft-arp.c
index a37155798e85e22da20517f1e41bdfb982ca9f5c..9805bbe0de87b276a79c8ae41115fd8261addd55 100644 (file)
--- a/iptables/nft-arp.c
+++ b/iptables/nft-arp.c
@@ -338,7 +338,8 @@ static void nft_arp_parse_payload(struct nft_xt_ctx *ctx,
        struct iptables_command_state *cs = data;
        struct arpt_entry *fw = &cs->arp;
        struct in_addr addr;
-       unsigned short int ar_hrd, ar_pro, ar_op, ar_hln;
+       uint16_t ar_hrd, ar_pro, ar_op;
+       uint8_t ar_hln;
        bool inv;
 
        switch (ctx->payload.offset) {
@@ -364,7 +365,7 @@ static void nft_arp_parse_payload(struct nft_xt_ctx *ctx,
                        fw->arp.invflags |= ARPT_INV_ARPOP;
                break;
        case offsetof(struct arphdr, ar_hln):
-               get_cmp_data(e, &ar_hln, sizeof(ar_op), &inv);
+               get_cmp_data(e, &ar_hln, sizeof(ar_hln), &inv);
                fw->arp.arhln = ar_hln;
                fw->arp.arhln_mask = 0xff;
                if (inv)