[systemd-devel] [PATCH] networkd DHCPv4 logging endian fix

[Paul Martin]

On Tue, Feb 10, 2015 at 08:10:43PM +0100, Lennart Poettering wrote:

> Hmm, I think it would be nicer to use be32toh() here instead, since it
> ensures the macro is (to a limited degree) typesafe.
> 
> Any chance you could rework that?

From: Paul Martin <paul.martin at codethink.co.uk>
Date: Wed, 11 Feb 2015 11:47:16 +0000
Subject: [PATCH] networkd dhcpv4 logging endian fix

On a big-endian host, systemd-networkd prints out IPv4 network
addresses byte reversed:

Feb 10 16:43:32 hostname systemd-networkd[151]: eth0 : DHCPv4 address 158.1.24.10/16 via 1.1.24.10

The address obtained is 10.24.1.158/16 and the route is

  10.24.0.0/16 dev eth0  src 10.24.1.187

The macro ADDRESS_FMT_VAL() unpacks a "struct in_addr" in a
little-endian specific manner.

This patch forces the passed address into host order, then unpacks it.

On an x86 later than i486, compiled with -O2, the only extra overhead
is a single bswap instruction.

---
 src/network/networkd-link.h | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/src/network/networkd-link.h b/src/network/networkd-link.h
index 449dbc8..dbbda02 100644
--- a/src/network/networkd-link.h
+++ b/src/network/networkd-link.h
@@ -22,6 +22,7 @@
 #pragma once
 
 #include "networkd.h"
+#include <endian.h>
 
 typedef enum LinkState {
         LINK_STATE_PENDING,
@@ -152,8 +153,8 @@ DEFINE_TRIVIAL_CLEANUP_FUNC(Link*, link_unref);
 
 #define log_link_struct(link, level, ...) log_struct(level, "INTERFACE=%s", link->ifname, __VA_ARGS__)
 
-#define ADDRESS_FMT_VAL(address)            \
-        (address).s_addr & 0xFF,            \
-        ((address).s_addr >> 8) & 0xFF,     \
-        ((address).s_addr >> 16) & 0xFF,    \
-        (address).s_addr >> 24
+#define ADDRESS_FMT_VAL(address)                   \
+        be32toh((address).s_addr) >> 24,           \
+        (be32toh((address).s_addr) >> 16) & 0xFFu, \
+        (be32toh((address).s_addr) >> 8) & 0xFFu,  \
+        be32toh((address).s_addr) & 0xFFu
-- 
2.1.4



-- 
Paul Martin                                  http://www.codethink.co.uk/
Senior Software Developer