Teach netstat(1) how to print the multicast group memberships present

within the running system.

Sponsored by:	Ralf the Wonder Llama

usr.bin/netstat/Makefile

@@ -2,7 +2,7 @@
 # $FreeBSD$
 
 PROG=	netstat
-SRCS=	if.c inet.c inet6.c main.c mbuf.c mroute.c ipx.c route.c \
+SRCS=	if.c inet.c inet6.c main.c mbuf.c mroute.c mcast.c ipx.c route.c \
 	unix.c atalk.c netgraph.c mroute6.c ipsec.c
 CFLAGS+=-DIPSEC
 CFLAGS+=-DINET6

usr.bin/netstat/main.c

@@ -493,6 +493,8 @@ main(int argc, char *argv[])
 					  nl[N_MIF6TABLE].n_value);
 #endif
 		}
+		putchar('\n');
+		ifmalist_dump();
 		exit(0);
 	}
 

usr.bin/netstat/mcast.c

@@ -0,0 +1,150 @@
+/*
+ * Copyright (c) 2004 Bruce M Simpson <bms@spc.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ */
+
+#ifndef lint
+static const char rcsid[] =
+  "$FreeBSD$";
+#endif /* not lint */
+
+/*
+ * Print the system's current multicast group memberships.
+ */
+
+#include <sys/types.h>
+#include <sys/socket.h>
+
+#include <net/if.h>
+#include <net/if_var.h>
+#include <net/if_mib.h>
+#include <net/if_types.h>
+#include <net/if_dl.h>
+#include <net/route.h>
+#include <netinet/in.h>
+#include <netinet/if_ether.h>
+#include <arpa/inet.h>
+#include <netdb.h>
+
+#include <ctype.h>
+#include <err.h>
+#include <ifaddrs.h>
+#include <sysexits.h>
+
+#include <stddef.h>
+#include <stdarg.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+
+#include "netstat.h"
+
+union sockunion {
+	struct sockaddr_storage	ss;
+	struct sockaddr		sa;
+	struct sockaddr_dl	sdl;
+	struct sockaddr_in	sin;
+	struct sockaddr_in6	sin6;
+};
+typedef union sockunion sockunion_t;
+
+#define MYIFNAME_SIZE 128
+
+void
+ifmalist_dump(void)
+{
+	struct ifmaddrs *ifmap, *ifma;
+	sockunion_t *psa;
+	char myifname[MYIFNAME_SIZE];
+	char addrbuf[INET6_ADDRSTRLEN];
+	char *pcolon;
+	void *addr;
+	char *pifname, *plladdr, *pgroup;
+
+	if (getifmaddrs(&ifmap))
+		err(EX_OSERR, "getifmaddrs");
+
+	fputs("IPv4/IPv6 Multicast Group Memberships\n", stdout);
+	fprintf(stdout, "%-20s\t%-16s\t%s\n", "Group", "Gateway", "Netif");
+
+	for (ifma = ifmap; ifma; ifma = ifma->ifma_next) {
+
+		if (ifma->ifma_name == NULL || ifma->ifma_addr == NULL)
+			continue;
+
+		/* Group address */
+		psa = (sockunion_t *)ifma->ifma_addr;
+		switch (psa->sa.sa_family) {
+		case AF_INET:
+			pgroup = inet_ntoa(psa->sin.sin_addr);
+			break;
+		case AF_INET6:
+			addr = &psa->sin6.sin6_addr;
+			inet_ntop(psa->sa.sa_family, addr, addrbuf,
+			    sizeof(addrbuf));
+			pgroup = addrbuf;
+			break;
+		default:
+			continue;	/* XXX */
+		}
+
+		/* Link-layer mapping, if any */
+		psa = (sockunion_t *)ifma->ifma_lladdr;
+		if (psa != NULL) {
+			switch (psa->sa.sa_family) {
+			case AF_INET:
+				plladdr = inet_ntoa(psa->sin.sin_addr);
+				break;
+			case AF_LINK:
+				if (psa->sdl.sdl_type == IFT_ETHER)
+					plladdr = ether_ntoa((struct ether_addr *)&psa->sdl.sdl_data);
+				else
+					plladdr = link_ntoa(&psa->sdl);
+				break;
+			}
+		} else
+			plladdr = "<none>";
+
+		/* Interface upon which the membership exists */
+		psa = (sockunion_t *)ifma->ifma_name;
+		switch (psa->sa.sa_family) {
+		case AF_LINK:
+			strlcpy(myifname, link_ntoa(&psa->sdl),
+			    MYIFNAME_SIZE);
+			pcolon = strchr(myifname, ':');
+			if (pcolon)
+				*pcolon = '\0';
+			pifname = myifname;
+			break;
+		default:
+			pifname = "";
+			break;
+		}
+
+		fprintf(stdout, "%-20s\t%-16s\t%s\n", pgroup, plladdr, pifname);
+	}
+
+	freeifmaddrs(ifmap);
+}

usr.bin/netstat/netstat.h

@@ -149,6 +149,6 @@ void	tp_protopr(u_long, const char *, int);
 void	tp_inproto(u_long);
 void	tp_stats(caddr_t, caddr_t);
 
+void	ifmalist_dump(void);
 void	mroutepr(u_long, u_long);
 void	mrt_stats(u_long);
-