net: add mac_pton() for parsing MAC address

mac_pton() parses MAC address in form XX:XX:XX:XX:XX:XX and only in that form.

mac_pton() doesn't dirty result until it's sure string representation is valid.

mac_pton() doesn't care about characters _after_ last octet,
it's up to caller to deal with it.

mac_pton() diverges from 0/-E return value convention.
Target usage:

	if (!mac_pton(str, whatever->mac))
		return -EINVAL;
	/* ->mac being u8 [ETH_ALEN] is filled at this point. */
	/* optionally check str[3 * ETH_ALEN - 1] for termination */

Use mac_pton() in pktgen and netconsole for start.

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 24 insertions, 0 deletions

diff --git a/net/core/utils.c b/net/core/utils.c
index 5fea0ab..2012bc7 100644
--- a/net/core/utils.c
+++ b/net/core/utils.c
@@ -296,3 +296,27 @@ void inet_proto_csum_replace4(__sum16 *sum, struct sk_buff *skb,
 				csum_unfold(*sum)));
 }
 EXPORT_SYMBOL(inet_proto_csum_replace4);
+
+int mac_pton(const char *s, u8 *mac)
+{
+	int i;
+
+	/* XX:XX:XX:XX:XX:XX */
+	if (strlen(s) < 3 * ETH_ALEN - 1)
+		return 0;
+
+	/* Don't dirty result unless string is valid MAC. */
+	for (i = 0; i < ETH_ALEN; i++) {
+		if (!strchr("0123456789abcdefABCDEF", s[i * 3]))
+			return 0;
+		if (!strchr("0123456789abcdefABCDEF", s[i * 3 + 1]))
+			return 0;
+		if (i != ETH_ALEN - 1 && s[i * 3 + 2] != ':')
+			return 0;
+	}
+	for (i = 0; i < ETH_ALEN; i++) {
+		mac[i] = (hex_to_bin(s[i * 3]) << 4) | hex_to_bin(s[i * 3 + 1]);
+	}
+	return 1;
+}
+EXPORT_SYMBOL(mac_pton);