1 /* $OpenBSD: nonxt-reflect.c,v 1.2 2018/05/21 01:19:21 bluhm Exp $ */
2 /*
3 * Copyright (c) Alexander Bluhm <bluhm@genua.de>
4 *
5 * Permission to use, copy, modify, and distribute this software for any
6 * purpose with or without fee is hereby granted, provided that the above
7 * copyright notice and this permission notice appear in all copies.
8 *
9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16 */
17
18 #include <sys/types.h>
19 #include <sys/socket.h>
20
21 #include <netdb.h>
22
23 #include <err.h>
24 #include <errno.h>
25 #include <stdio.h>
26 #include <stdlib.h>
27 #include <string.h>
28 #include <unistd.h>
29
30 void __dead usage(void);
31
32 void
usage(void)33 usage(void)
34 {
35 fprintf(stderr, "usage: nonxt-reflect localaddr\n"
36 "Daemonize, wait for protocol 59 packets, and answer them.\n");
37 exit(1);
38 }
39
40 int
main(int argc,char * argv[])41 main(int argc, char *argv[])
42 {
43 struct addrinfo hints, *res, *res0;
44 const char *cause = NULL, *local;
45 int error;
46 int save_errno;
47 int s;
48 char buf[1024];
49
50 switch (argc) {
51 case 2:
52 local = argv[1];
53 break;
54 default:
55 usage();
56 }
57
58 if (pledge("stdio inet dns proc", NULL) == -1)
59 err(1, "pledge");
60
61 /* Create socket and bind it to local address. */
62 memset(&hints, 0, sizeof(hints));
63 hints.ai_family = AF_UNSPEC;
64 hints.ai_socktype = SOCK_RAW;
65 hints.ai_protocol = IPPROTO_NONE;
66 hints.ai_flags = AI_PASSIVE;
67 error = getaddrinfo(local, NULL, &hints, &res0);
68 if (error)
69 errx(1, "getaddrinfo local: %s", gai_strerror(error));
70 for (res = res0; res; res = res->ai_next) {
71 s = socket(res->ai_family, res->ai_socktype, res->ai_protocol);
72 if (s == -1) {
73 cause = "socket";
74 continue;
75 }
76 if (bind(s, res->ai_addr, res->ai_addrlen) == -1) {
77 cause = "bind";
78 save_errno = errno;
79 close(s);
80 errno = save_errno;
81 continue;
82 }
83 break;
84 }
85 if (res == NULL)
86 err(1, "%s", cause);
87 freeaddrinfo(res0);
88
89 /* Socket is ready to receive, parent process may proceed. */
90 daemon(1, 1);
91 if (pledge("stdio inet", NULL) == -1)
92 err(1, "pledge");
93
94 for (;;) {
95 struct sockaddr_storage ss;
96 socklen_t slen;
97
98 /* Receive a protocol 59 packet. */
99 slen = sizeof(ss);
100 if (recvfrom(s, buf, sizeof(buf), 0, (struct sockaddr *)&ss,
101 &slen) == -1)
102 err(1, "recv");
103 /* Send back a reply packet. */
104 if (sendto(s, buf, 0, 0, (struct sockaddr *)&ss, slen) == -1)
105 err(1, "send");
106 }
107
108 /* NOTREACHED */
109 return 0;
110 }
111