// SPDX-License-Identifier: GPL-2.0

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <arpa/inet.h>

static void set_addr(struct sockaddr_storage *ss, char *ip, char *port, int *len)
{
        if (ss->ss_family == AF_INET) {
                struct sockaddr_in *a = (struct sockaddr_in *)ss;

                a->sin_addr.s_addr = inet_addr(ip);
                a->sin_port = htons(atoi(port));
                *len = sizeof(*a);
        } else {
                struct sockaddr_in6 *a = (struct sockaddr_in6 *)ss;

                a->sin6_family = AF_INET6;
                inet_pton(AF_INET6, ip, &a->sin6_addr);
                a->sin6_port = htons(atoi(port));
                *len = sizeof(*a);
        }
}

static int do_client(int argc, char *argv[])
{
        struct sockaddr_storage ss;
        int csk, ret, len;

        if (argc < 5) {
                printf("%s client -4|6 IP PORT [IP PORT]\n", argv[0]);
                return -1;
        }

        bzero((void *)&ss, sizeof(ss));
        ss.ss_family = !strcmp(argv[2], "-4") ? AF_INET : AF_INET6;
        csk = socket(ss.ss_family, SOCK_STREAM, IPPROTO_SCTP);
        if (csk < 0) {
                printf("failed to create socket\n");
                return -1;
        }

        if (argc >= 7) {
                set_addr(&ss, argv[5], argv[6], &len);
                ret = bind(csk, (struct sockaddr *)&ss, len);
                if (ret < 0) {
                        printf("failed to bind to address\n");
                        return -1;
                }
        }

        set_addr(&ss, argv[3], argv[4], &len);
        ret = connect(csk, (struct sockaddr *)&ss, len);
        if (ret < 0)
                return -1;

        recv(csk, NULL, 0, 0);
        close(csk);

        return 0;
}

int main(int argc, char *argv[])
{
        struct sockaddr_storage ss;
        int lsk, csk, ret, len;

        if (argc < 2 || (strcmp(argv[1], "server") && strcmp(argv[1], "client"))) {
                printf("%s server|client ...\n", argv[0]);
                return -1;
        }

        if (!strcmp(argv[1], "client"))
                return do_client(argc, argv);

        if (argc < 5) {
                printf("%s server -4|6 IP PORT [IFACE]\n", argv[0]);
                return -1;
        }

        ss.ss_family = !strcmp(argv[2], "-4") ? AF_INET : AF_INET6;
        lsk = socket(ss.ss_family, SOCK_STREAM, IPPROTO_SCTP);
        if (lsk < 0) {
                printf("failed to create lsk\n");
                return -1;
        }

        if (argc >= 6) {
                ret = setsockopt(lsk, SOL_SOCKET, SO_BINDTODEVICE,
                                 argv[5], strlen(argv[5]) + 1);
                if (ret < 0) {
                        printf("failed to bind to device\n");
                        return -1;
                }
        }

        set_addr(&ss, argv[3], argv[4], &len);
        ret = bind(lsk, (struct sockaddr *)&ss, len);
        if (ret < 0) {
                printf("failed to bind to address\n");
                return -1;
        }

        ret = listen(lsk, 5);
        if (ret < 0) {
                printf("failed to listen on port\n");
                return -1;
        }

        csk = accept(lsk, (struct sockaddr *)NULL, (socklen_t *)NULL);
        if (csk < 0) {
                printf("failed to accept new client\n");
                return -1;
        }

        close(csk);
        close(lsk);

        return 0;
}