netdev - [PATCH net-next 1/3] ethernet: Add helpers to recognize addresses mapped to IP multicast

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Message-Id: <20220822140800.2651029-2-casper.casan@gmail.com>
Date:   Mon, 22 Aug 2022 16:07:58 +0200
From:   Casper Andersson <casper.casan@...il.com>
To:     "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, netdev@...r.kernel.org
Cc:     Horatiu Vultur <horatiu.vultur@...rochip.com>,
        Lars Povlsen <lars.povlsen@...rochip.com>,
        Steen Hegelund <Steen.Hegelund@...rochip.com>,
        UNGLinuxDriver@...rochip.com
Subject: [PATCH net-next 1/3] ethernet: Add helpers to recognize addresses mapped to IP multicast

IP multicast must sometimes be discriminated from non-IP multicast,
e.g. when determining the forwarding behavior of a given group in the
presence of multicast router ports on an offloaded bridge. Therefore,
provide helpers to identify these groups.

Signed-off-by: Casper Andersson <casper.casan@...il.com>
---
 include/linux/etherdevice.h | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/include/linux/etherdevice.h b/include/linux/etherdevice.h
index 92b10e67d5f8..a541f0c4f146 100644
--- a/include/linux/etherdevice.h
+++ b/include/linux/etherdevice.h
@@ -428,6 +428,28 @@ static inline bool ether_addr_equal_masked(const u8 *addr1, const u8 *addr2,
 	return true;
 }
 
+static inline bool ether_addr_is_ipv4_mcast(const u8 *addr)
+{
+	u8 base[ETH_ALEN] = { 0x01, 0x00, 0x5e, 0x00, 0x00, 0x00 };
+	u8 mask[ETH_ALEN] = { 0xff, 0xff, 0xff, 0x80, 0x00, 0x00 };
+
+	return ether_addr_equal_masked(addr, base, mask);
+}
+
+static inline bool ether_addr_is_ipv6_mcast(const u8 *addr)
+{
+	u8 base[ETH_ALEN] = { 0x33, 0x33, 0x00, 0x00, 0x00, 0x00 };
+	u8 mask[ETH_ALEN] = { 0xff, 0xff, 0x00, 0x00, 0x00, 0x00 };
+
+	return ether_addr_equal_masked(addr, base, mask);
+}
+
+static inline bool ether_addr_is_ip_mcast(const u8 *addr)
+{
+	return ether_addr_is_ipv4_mcast(addr) ||
+		ether_addr_is_ipv6_mcast(addr);
+}
+
 /**
  * ether_addr_to_u64 - Convert an Ethernet address into a u64 value.
  * @addr: Pointer to a six-byte array containing the Ethernet address
-- 
2.34.1