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/*-
* SPDX-License-Identifier: BSD-2-Clause
*
* Copyright (c) 2025 Gleb Smirnoff <glebius@FreeBSD.org>
*
* 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.
*/
#include <sys/socket.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <arpa/inet.h>
#include <net/if.h>
#include <assert.h>
#include <errno.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <limits.h>
#include <err.h>
static in_port_t
atop(const char *c)
{
unsigned long ul;
errno = 0;
if ((ul = strtol(c, NULL, 10)) < 1 || ul > IPPORT_MAX || errno != 0)
err(1, "can't parse %s", c);
return ((in_port_t)ul);
}
int
main(int argc, char *argv[])
{
char buf[IP_MAXPACKET + 1];
struct sockaddr_in sin = {
.sin_family = AF_INET,
.sin_len = sizeof(struct sockaddr_in),
};
socklen_t slen = sizeof(struct sockaddr_in);
struct in_addr maddr, ifaddr;
ssize_t len;
int s, ifindex;
bool index;
if (argc < 4)
usage:
errx(1, "Usage: %s (ip_mreq|ip_mreqn|group_req) "
"IPv4-group port interface", argv[0]);
if (inet_pton(AF_INET, argv[2], &maddr) != 1)
err(1, "inet_pton(%s) failed", argv[2]);
sin.sin_port = htons(atop(argv[3]));
if (inet_pton(AF_INET, argv[4], &ifaddr) == 1)
index = false;
else if ((ifindex = if_nametoindex(argv[4])) > 0)
index = true;
else if (strcmp(argv[4], "0") == 0) {
ifindex = 0;
index = true;
} else
err(1, "if_nametoindex(%s) failed", argv[4]);
assert((s = socket(PF_INET, SOCK_DGRAM, 0)) > 0);
assert(bind(s, (struct sockaddr *)&sin, sizeof(sin)) == 0);
if (strcmp(argv[1], "ip_mreq") == 0) {
if (index)
errx(1, "ip_mreq doesn't accept index");
struct ip_mreq mreq = {
.imr_multiaddr = maddr,
.imr_interface = ifaddr,
};
assert(setsockopt(s, IPPROTO_IP, IP_ADD_MEMBERSHIP, &mreq,
sizeof(mreq)) == 0);
} else if (strcmp(argv[1], "ip_mreqn") == 0) {
/*
* ip_mreqn shall be used with index, but for testing
* purposes accept address too.
*/
struct ip_mreqn mreqn = {
.imr_multiaddr = maddr,
.imr_address = index ? (struct in_addr){ 0 } : ifaddr,
.imr_ifindex = index ? ifindex : 0,
};
assert(setsockopt(s, IPPROTO_IP, IP_ADD_MEMBERSHIP, &mreqn,
sizeof(mreqn)) == 0);
} else if (strcmp(argv[1], "group_req") == 0) {
if (!index)
errx(1, "group_req expects index");
struct group_req greq = { .gr_interface = ifindex };
struct sockaddr_in *gsa = (struct sockaddr_in *)&greq.gr_group;
gsa->sin_family = AF_INET;
gsa->sin_len = sizeof(struct sockaddr_in);
gsa->sin_addr = maddr;
assert(setsockopt(s, IPPROTO_IP, MCAST_JOIN_GROUP, &greq,
sizeof(greq)) == 0);
} else
goto usage;
assert((len = recvfrom(s, buf, sizeof(buf) - 1, 0,
(struct sockaddr *)&sin, &slen)) > 0);
buf[len] = '\0';
printf("%s:%u %s\n", inet_ntoa(sin.sin_addr), ntohs(sin.sin_port), buf);
return (0);
}
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