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// SPDX-License-Identifier: GPL-2.0-or-later
#include <errno.h>
#include <error.h>
#include <netdb.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <linux/icmp.h>
#include <linux/icmpv6.h>
#include <linux/types.h>
#include <linux/udp.h>
#include <sys/socket.h>
enum {
ERN_SUCCESS = 0,
/* Well defined errors, callers may depend on these */
ERN_SEND = 1,
/* Informational, can reorder */
ERN_HELP,
ERN_SEND_SHORT,
ERN_SOCK_CREATE,
ERN_RESOLVE,
ERN_CMSG_WR,
};
struct options {
bool silent_send;
const char *host;
const char *service;
struct {
unsigned int mark;
} sockopt;
struct {
unsigned int family;
unsigned int type;
unsigned int proto;
} sock;
struct {
bool ena;
unsigned int val;
} mark;
} opt = {
.sock = {
.family = AF_UNSPEC,
.type = SOCK_DGRAM,
.proto = IPPROTO_UDP,
},
};
static void __attribute__((noreturn)) cs_usage(const char *bin)
{
printf("Usage: %s [opts] <dst host> <dst port / service>\n", bin);
printf("Options:\n"
"\t\t-s Silent send() failures\n"
"\t\t-4/-6 Force IPv4 / IPv6 only\n"
"\t\t-p prot Socket protocol\n"
"\t\t (u = UDP (default); i = ICMP; r = RAW)\n"
"\n"
"\t\t-m val Set SO_MARK with given value\n"
"\t\t-M val Set SO_MARK via setsockopt\n"
"");
exit(ERN_HELP);
}
static void cs_parse_args(int argc, char *argv[])
{
char o;
while ((o = getopt(argc, argv, "46sp:m:M:")) != -1) {
switch (o) {
case 's':
opt.silent_send = true;
break;
case '4':
opt.sock.family = AF_INET;
break;
case '6':
opt.sock.family = AF_INET6;
break;
case 'p':
if (*optarg == 'u' || *optarg == 'U') {
opt.sock.proto = IPPROTO_UDP;
} else if (*optarg == 'i' || *optarg == 'I') {
opt.sock.proto = IPPROTO_ICMP;
} else if (*optarg == 'r') {
opt.sock.type = SOCK_RAW;
} else {
printf("Error: unknown protocol: %s\n", optarg);
cs_usage(argv[0]);
}
break;
case 'm':
opt.mark.ena = true;
opt.mark.val = atoi(optarg);
break;
case 'M':
opt.sockopt.mark = atoi(optarg);
break;
}
}
if (optind != argc - 2)
cs_usage(argv[0]);
opt.host = argv[optind];
opt.service = argv[optind + 1];
}
static void
cs_write_cmsg(struct msghdr *msg, char *cbuf, size_t cbuf_sz)
{
struct cmsghdr *cmsg;
size_t cmsg_len;
msg->msg_control = cbuf;
cmsg_len = 0;
if (opt.mark.ena) {
cmsg = (struct cmsghdr *)(cbuf + cmsg_len);
cmsg_len += CMSG_SPACE(sizeof(__u32));
if (cbuf_sz < cmsg_len)
error(ERN_CMSG_WR, EFAULT, "cmsg buffer too small");
cmsg->cmsg_level = SOL_SOCKET;
cmsg->cmsg_type = SO_MARK;
cmsg->cmsg_len = CMSG_LEN(sizeof(__u32));
*(__u32 *)CMSG_DATA(cmsg) = opt.mark.val;
}
if (cmsg_len)
msg->msg_controllen = cmsg_len;
else
msg->msg_control = NULL;
}
int main(int argc, char *argv[])
{
char buf[] = "blablablabla";
struct addrinfo hints, *ai;
struct iovec iov[1];
struct msghdr msg;
char cbuf[1024];
int err;
int fd;
cs_parse_args(argc, argv);
memset(&hints, 0, sizeof(hints));
hints.ai_family = opt.sock.family;
ai = NULL;
err = getaddrinfo(opt.host, opt.service, &hints, &ai);
if (err) {
fprintf(stderr, "Can't resolve address [%s]:%s\n",
opt.host, opt.service);
return ERN_SOCK_CREATE;
}
if (ai->ai_family == AF_INET6 && opt.sock.proto == IPPROTO_ICMP)
opt.sock.proto = IPPROTO_ICMPV6;
fd = socket(ai->ai_family, opt.sock.type, opt.sock.proto);
if (fd < 0) {
fprintf(stderr, "Can't open socket: %s\n", strerror(errno));
freeaddrinfo(ai);
return ERN_RESOLVE;
}
if (opt.sock.proto == IPPROTO_ICMP) {
buf[0] = ICMP_ECHO;
buf[1] = 0;
} else if (opt.sock.proto == IPPROTO_ICMPV6) {
buf[0] = ICMPV6_ECHO_REQUEST;
buf[1] = 0;
} else if (opt.sock.type == SOCK_RAW) {
struct udphdr hdr = { 1, 2, htons(sizeof(buf)), 0 };
struct sockaddr_in6 *sin6 = (void *)ai->ai_addr;;
memcpy(buf, &hdr, sizeof(hdr));
sin6->sin6_port = htons(opt.sock.proto);
}
if (opt.sockopt.mark &&
setsockopt(fd, SOL_SOCKET, SO_MARK,
&opt.sockopt.mark, sizeof(opt.sockopt.mark)))
error(ERN_SOCKOPT, errno, "setsockopt SO_MARK");
iov[0].iov_base = buf;
iov[0].iov_len = sizeof(buf);
memset(&msg, 0, sizeof(msg));
msg.msg_name = ai->ai_addr;
msg.msg_namelen = ai->ai_addrlen;
msg.msg_iov = iov;
msg.msg_iovlen = 1;
cs_write_cmsg(&msg, cbuf, sizeof(cbuf));
err = sendmsg(fd, &msg, 0);
if (err < 0) {
if (!opt.silent_send)
fprintf(stderr, "send failed: %s\n", strerror(errno));
err = ERN_SEND;
} else if (err != sizeof(buf)) {
fprintf(stderr, "short send\n");
err = ERN_SEND_SHORT;
} else {
err = ERN_SUCCESS;
}
close(fd);
freeaddrinfo(ai);
return err;
}
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