[PATCH v3 1/2] lib/net_utils: allow mac_pton() to take a custom delimiter

[Liu Chao]

mac_pton() hardcodes ':' as the only accepted separator, which pushes
callers that need a different notation to open-code their own parser.

Split the body out into parse_mac_pton() taking the set of accepted
delimiters as a string, and turn mac_pton() into a static inline wrapper
passing ":" so that every existing caller keeps its current behaviour.
The strnlen() guard still runs before any delimiter is inspected, so
strchr() is never handed a NUL character.

No functional change intended.

Suggested-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxx>
Signed-off-by: Liu Chao <liuc63@xxxxxxxxxxxx>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxx>
---
v3: pick up Andy's Reviewed-by, no code change.
v2: new patch, split out of the u_ether fix at Andy's suggestion.
Link: https://lore.kernel.org/all/20261104025058.2650911-2-liuc63@xxxxxxxxxxxx/

 include/linux/hex.h |  7 ++++++-
 lib/net_utils.c     | 17 ++++++++++++++---
 2 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/include/linux/hex.h b/include/linux/hex.h
index 2618382e5b0c..408825478cda 100644
--- a/include/linux/hex.h
+++ b/include/linux/hex.h
@@ -30,6 +30,11 @@ extern int hex_to_bin(unsigned char ch);
 extern int __must_check hex2bin(u8 *dst, const char *src, size_t count);
 extern char *bin2hex(char *dst, const void *src, size_t count);
 
-bool mac_pton(const char *s, u8 *mac);
+bool parse_mac_pton(const char *s, u8 *mac, const char *delim);
+
+static inline bool mac_pton(const char *s, u8 *mac)
+{
+	return parse_mac_pton(s, mac, ":");
+}
 
 #endif
diff --git a/lib/net_utils.c b/lib/net_utils.c
index 215cda672fee..011857cc978b 100644
--- a/lib/net_utils.c
+++ b/lib/net_utils.c
@@ -5,7 +5,18 @@
 #include <linux/export.h>
 #include <linux/hex.h>
 
-bool mac_pton(const char *s, u8 *mac)
+/**
+ * parse_mac_pton - convert a MAC address string using a custom delimiter
+ * @s: string to be parsed
+ * @mac: buffer to store the result, left untouched if @s is malformed
+ * @delim: characters accepted as a separator between the byte pairs
+ *
+ * @s must be MAC_ADDR_STR_LEN characters long and use a character from
+ * @delim at every separator position, e.g. "aa.bb:cc.dd:ee.ff" with ".:".
+ *
+ * Return: true on success, false if @s is malformed.
+ */
+bool parse_mac_pton(const char *s, u8 *mac, const char *delim)
 {
 	int i;
 
@@ -16,7 +27,7 @@ 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 && !strchr(delim, s[i * 3 + 2]))
 			return false;
 	}
 	for (i = 0; i < ETH_ALEN; i++) {
@@ -24,4 +35,4 @@ bool mac_pton(const char *s, u8 *mac)
 	}
 	return true;
 }
-EXPORT_SYMBOL(mac_pton);
+EXPORT_SYMBOL(parse_mac_pton);
-- 
2.50.1