netdev - Re: [PATCH 3/7] net: replace NIPQUAD() in net/netfilter/

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Message-Id: <1225734196.5361.5.camel@brick>
Date:	Mon, 03 Nov 2008 09:43:16 -0800
From:	Harvey Harrison <harvey.harrison@...il.com>
To:	Julius Volz <julius.volz@...il.com>
Cc:	David Miller <davem@...emloft.net>,
	linux-netdev <netdev@...r.kernel.org>
Subject: Re: [PATCH 3/7] net: replace NIPQUAD() in net/netfilter/

On Mon, 2008-11-03 at 17:56 +0100, Julius Volz wrote:
> Hi,
> I just noticed that this breaks IPv4 addresses in IPVS debug output
> (didn't check in other places). It seems that during integer to ASCII
> conversion, the converted digits are output the wrong way around (not
> endianness though). For example, 10.0.0.254 is output as 01.0.0.452.
> Could something be wrong with ip4_addr_string() or put_dec_trunc() in
> lib/vsprintf.c?

Mea Culpa, I was testing with a too-simple case, it does reverse the digits,
can you try this:

From: Harvey Harrison <harvey.harrison@...il.com>
[PATCH] printk: ipv4 address digits printed in reverse order

put_dec_trunc prints the digits in reverse order and is reversed
inside number(). Continue using put_dec_trunc, but reverse each quad
in ip4_addr_string.

[Noticed by Julius Volz]

Signed-off-by: Harvey Harrison <harvey.harrison@...il.com>
---
 lib/vsprintf.c |    8 ++++++--
 1 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index dd7cc7f..6897724 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -620,11 +620,15 @@ static char *ip4_addr_string(char *buf, char *end, u8 *addr, int field_width,
 			 int precision, int flags)
 {
 	char ip4_addr[4 * 4]; /* (4 * 3 decimal digits), 3 dots and trailing zero */
+	char temp[3];	/* hold each IP quad in reverse order */
 	char *p = ip4_addr;
-	int i;
+	int i, digits;
 
 	for (i = 0; i < 4; i++) {
-		p = put_dec_trunc(p, addr[i]);
+		digits = put_dec_trunc(temp, addr[i]) - temp;
+		/* reverse the digits in the quad */
+		while (digits--)
+			*p++ = temp[digits];
 		if (i != 3)
 			*p++ = '.';
 	}
-- 
1.6.0.3.756.gb776d



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