/*      $OpenBSD: nonxt-sendrecv.c,v 1.2 2018/05/21 01:19:21 bluhm Exp $        */
/*
 * Copyright (c) Alexander Bluhm <bluhm@genua.de>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <sys/types.h>
#include <sys/socket.h>

#include <netdb.h>

#include <err.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

void __dead usage(void);

void
usage(void)
{
        fprintf(stderr, "usage: nonxt-sendrecv [localaddr] remoteaddr\n"
            "Send empty protocol 59 packet and wait for answer.\n");
        exit(1);
}

int
main(int argc, char *argv[])
{
        struct addrinfo hints, *res, *res0;
        struct timeval to;
        const char *cause = NULL, *local, *remote;
        int error;
        int save_errno;
        int s;
        char buf[1024];

        switch (argc) {
        case 2:
                local = NULL;
                remote = argv[1];
                break;
        case 3:
                local = argv[1];
                remote = argv[2];
                break;
        default:
                usage();
        }

        if (pledge("stdio inet dns", NULL) == -1)
                err(1, "pledge");

        /* Create socket and connect it to remote address. */
        memset(&hints, 0, sizeof(hints));
        hints.ai_family = AF_UNSPEC;
        hints.ai_socktype = SOCK_RAW;
        hints.ai_protocol = IPPROTO_NONE;
        error = getaddrinfo(remote, NULL, &hints, &res0);
        if (error)
                errx(1, "getaddrinfo remote: %s", gai_strerror(error));
        for (res = res0; res; res = res->ai_next) {
                s = socket(res->ai_family, res->ai_socktype, res->ai_protocol);
                if (s == -1) {
                        cause = "socket";
                        continue;
                }
                if (connect(s, res->ai_addr, res->ai_addrlen) == -1) {
                        cause = "connect";
                        save_errno = errno;
                        close(s);
                        errno = save_errno;
                        continue;
                }
                break;
        }
        if (res == NULL)
                err(1, "%s", cause);

        /* Optionally bind the socket to local address. */
        if (local != NULL) {
                memset(&hints, 0, sizeof(hints));
                hints.ai_family = res->ai_family;
                hints.ai_socktype = SOCK_RAW;
                hints.ai_protocol = IPPROTO_NONE;
                hints.ai_flags = AI_PASSIVE;
                freeaddrinfo(res0);
                error = getaddrinfo(local, NULL, &hints, &res0);
                if (error)
                        errx(1, "getaddrinfo local: %s", gai_strerror(error));
                for (res = res0; res; res = res->ai_next) {
                        if (bind(s, res->ai_addr, res->ai_addrlen) == -1)
                                continue;
                        break;
                }
                if (res == NULL)
                        err(1, "bind");
        }
        freeaddrinfo(res0);

        if (pledge("stdio inet", NULL) == -1)
                err(1, "pledge");

        /* Send a protocol 59 packet. */
        if (send(s, buf, 0, 0) == -1)
                err(1, "send");
        /* Wait for up to 3 seconds to receive a reply packet. */
        to.tv_sec = 3;
        to.tv_usec = 0;
        if (setsockopt(s, SOL_SOCKET, SO_RCVTIMEO, &to, sizeof(to)) == -1)
                err(1, "setsockopt");
        if (recv(s, buf, sizeof(buf), 0) == -1)
                err(1, "recv");

        return 0;
}