[PATCH v1 0/2] mac_pton: support more MAC address formats

[PATCH v1 0/2] mac_pton: support more MAC address formats

[Michael Pratt]

Currently, mac_pton() strictly requires the standard ASCII MAC address format
with colons as the delimiter, however,
some hardware vendors don't store the address like that.

If there is no delimiter, one could use strtoul()
but that would leave out important checks to make sure
that each character in the string is hexadecimal.

This series adds support for other delimiters
and lack of any delimiter to the mac_pton() function.

Tested with Openwrt on a MIPS system (ar9344).

[PATCH 1/2] mac_pton: support MAC addresses with other delimiters

[Michael Pratt]

From: Michael Pratt <mcpratt@pm.me>

Some network hardware vendors may do something unique
when storing the MAC address into hardware in ASCII,
like using hyphens as the delimiter.

Allow parsing of MAC addresses with a non-standard
delimiter (punctuation other than a colon).

e.g. aa-bb-cc-dd-ee-ff

Signed-off-by: Michael Pratt <mcpratt@pm.me>
---
 lib/net_utils.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/net_utils.c b/lib/net_utils.c
index 42bb0473fb22..ecb7625e1dec 100644
--- a/lib/net_utils.c
+++ b/lib/net_utils.c
@@ -18,7 +18,7 @@ bool mac_pton(const char *s, u8 *mac)
 	for (i = 0; i < ETH_ALEN; i++) {
 		if (!isxdigit(s[i * 3]) || !isxdigit(s[i * 3 + 1]))
 			return false;
-		if (i != ETH_ALEN - 1 && s[i * 3 + 2] != ':')
+		if (i != ETH_ALEN - 1 && !ispunct(s[i * 3 + 2]))
 			return false;
 	}
 	for (i = 0; i < ETH_ALEN; i++) {
-- 
2.30.2

Re: [PATCH 1/2] mac_pton: support MAC addresses with other delimiters

[Stephen Hemminger]

On Mon, 02 Oct 2023 23:40:02 +0000
Michael Pratt <mcpratt@protonmail.com> wrote:

> From: Michael Pratt <mcpratt@pm.me>
> 
> Some network hardware vendors may do something unique
> when storing the MAC address into hardware in ASCII,
> like using hyphens as the delimiter.
> 
> Allow parsing of MAC addresses with a non-standard
> delimiter (punctuation other than a colon).
> 
> e.g. aa-bb-cc-dd-ee-ff
> 
> Signed-off-by: Michael Pratt <mcpratt@pm.me>
> ---
>  lib/net_utils.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/lib/net_utils.c b/lib/net_utils.c
> index 42bb0473fb22..ecb7625e1dec 100644
> --- a/lib/net_utils.c
> +++ b/lib/net_utils.c
> @@ -18,7 +18,7 @@ bool mac_pton(const char *s, u8 *mac)
>  	for (i = 0; i < ETH_ALEN; i++) {
>  		if (!isxdigit(s[i * 3]) || !isxdigit(s[i * 3 + 1]))
>  			return false;
> -		if (i != ETH_ALEN - 1 && s[i * 3 + 2] != ':')
> +		if (i != ETH_ALEN - 1 && !ispunct(s[i * 3 + 2]))

Having looked at same thing in DPDK already, this looks overly broad.
There are only two common formats in the standards (isn't it fun
when standards disagree). IETF uses colon separator and IEEE uses
hyphen separator. Linux convention is colon, and  Windows convention
is hyphen. There is also the old Cisco 3 part format with periods
but adding that makes no sense.

Also, it would be bad to allow bogus values where two different
types of punctuation are used.

[PATCH 2/2] mac_pton: support MAC addresses without delimiters

[Michael Pratt]

From: Michael Pratt <mcpratt@pm.me>

Some network hardware vendors may do something unique
when storing the MAC address into hardware in ASCII,
like leaving out delimiters in order to avoid
using more than a single 16-byte logical addressing line.

Allow parsing of MAC addresses without a delimiter.

Signed-off-by: Michael Pratt <mcpratt@pm.me>
---
 lib/net_utils.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/lib/net_utils.c b/lib/net_utils.c
index ecb7625e1dec..f5fd1926af59 100644
--- a/lib/net_utils.c
+++ b/lib/net_utils.c
@@ -7,9 +7,14 @@
 
 bool mac_pton(const char *s, u8 *mac)
 {
+	size_t minlen = 2 * ETH_ALEN;
 	size_t maxlen = 3 * ETH_ALEN - 1;
 	int i;
 
+	/* AABBCCDDEEFF */
+	if (strnlen(s, maxlen) == minlen)
+		goto no_delim;
+
 	/* XX:XX:XX:XX:XX:XX */
 	if (strnlen(s, maxlen) < maxlen)
 		return false;
@@ -25,5 +30,15 @@ bool mac_pton(const char *s, u8 *mac)
 		mac[i] = (hex_to_bin(s[i * 3]) << 4) | hex_to_bin(s[i * 3 + 1]);
 	}
 	return true;
+
+no_delim:
+	for (i = 0; i < minlen; i++) {
+		if (!isxdigit(s[i]))
+			return false;
+	}
+	for (i = 0; i < ETH_ALEN; i++) {
+		mac[i] = (hex_to_bin(s[i * 2]) << 4) | hex_to_bin(s[i * 2 + 1]);
+	}
+	return true;
 }
 EXPORT_SYMBOL(mac_pton);
-- 
2.30.2

Re: [PATCH v1 0/2] mac_pton: support more MAC address formats

[Simon Horman]

On Mon, Oct 02, 2023 at 11:39:55PM +0000, Michael Pratt wrote:
> Currently, mac_pton() strictly requires the standard ASCII MAC address format
> with colons as the delimiter, however,
> some hardware vendors don't store the address like that.
> 
> If there is no delimiter, one could use strtoul()
> but that would leave out important checks to make sure
> that each character in the string is hexadecimal.
> 
> This series adds support for other delimiters
> and lack of any delimiter to the mac_pton() function.
> 
> Tested with Openwrt on a MIPS system (ar9344).

Hi Michael,

I am wondering if you considered a different approach where,
via parameters and/or new helpers, callers can specify the
delimiter, or absence thereof.