[openib-general] [PATCH][RFC/v1][10/12] IPoIB IPv4 multicast

[Roland Dreier]

Add ip_ib_mc_map() to convert IPv$ multicast addresses to IPoIB
hardware addresses.

The mapping for multicast addresses is described in
  http://www.ietf.org/internet-drafts/draft-ietf-ipoib-ip-over-infiniband-07.txt

Signed-off-by: Roland Dreier <roland at topspin.com>


Index: linux-bk/include/net/ip.h
===================================================================
--- linux-bk.orig/include/net/ip.h	2004-11-17 19:52:25.000000000 -0800
+++ linux-bk/include/net/ip.h	2004-11-18 10:51:45.214387812 -0800
@@ -229,6 +229,39 @@
 	buf[3]=addr&0x7F;
 }
 
+/*
+ *	Map a multicast IP onto multicast MAC for type IP-over-InfiniBand.
+ *	Leave P_Key as 0 to be filled in by driver.
+ */
+
+static inline void ip_ib_mc_map(u32 addr, char *buf)
+{
+	buf[0]  = 0;		/* Reserved */
+	buf[1]  = 0xff;		/* Multicast QPN */
+	buf[2]  = 0xff;
+	buf[3]  = 0xff;
+	addr    = ntohl(addr);
+	buf[4]  = 0xff;
+	buf[5]  = 0x12;		/* link local scope */
+	buf[6]  = 0x40;		/* IPv4 signature */
+	buf[7]  = 0x1b;
+	buf[8]  = 0;		/* P_Key */
+	buf[9]  = 0;
+	buf[10] = 0;
+	buf[11] = 0;
+	buf[12] = 0;
+	buf[13] = 0;
+	buf[14] = 0;
+	buf[15] = 0;
+	buf[19] = addr & 0xff;
+	addr  >>= 8;
+	buf[18] = addr & 0xff;
+	addr  >>= 8;
+	buf[17] = addr & 0xff;
+	addr  >>= 8;
+	buf[16] = addr & 0x0f;
+}
+
 #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
 #include <linux/ipv6.h>
 #endif
Index: linux-bk/net/ipv4/arp.c
===================================================================
--- linux-bk.orig/net/ipv4/arp.c	2004-11-17 19:52:34.000000000 -0800
+++ linux-bk/net/ipv4/arp.c	2004-11-18 10:51:45.214387812 -0800
@@ -213,6 +213,9 @@
 	case ARPHRD_IEEE802_TR:
 		ip_tr_mc_map(addr, haddr);
 		return 0;
+	case ARPHRD_INFINIBAND:
+		ip_ib_mc_map(addr, haddr);
+		return 0;
 	default:
 		if (dir) {
 			memcpy(haddr, dev->broadcast, dev->addr_len);