/*      $OpenBSD: mmap-sysctl-copyout.c,v 1.3 2021/12/13 16:56:50 deraadt Exp $ */

#include <sys/types.h>
#include <sys/mman.h>
#include <sys/queue.h>
#include <sys/socket.h>
#include <sys/sysctl.h>

#include <netinet/in.h>
#include <netinet/tcp.h>
#include <netinet/tcp_seq.h>
#include <netinet/tcp_timer.h>
#include <netinet/tcp_var.h>

#include <err.h>
#include <fcntl.h>
#include <stdlib.h>
#include <limits.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>

#define FILE    "sysctl-net.inet.tcp.stats"
#define CLIENT  "/mnt/regress-nfs-client"
#define SERVER  "/mnt/regress-nfs-server"

int
main(void)
{
        char *p, path[PATH_MAX];
        int mib[] = { CTL_NET, PF_INET, IPPROTO_TCP, TCPCTL_STATS };
        u_int miblen = sizeof(mib) / sizeof(mib[0]);
        struct tcpstat stats;
        int fd;
        size_t len;
        ssize_t n;

        /*
         * Initialize file on NFS server.
         */
        snprintf(path, sizeof(path), "%s/%s", SERVER, FILE);
        if ((fd = open(path, O_RDWR|O_CREAT|O_TRUNC, 0777)) == -1)
                err(1, "open write '%s'", path);
        len = sizeof(struct tcpstat);
        memset(&stats, 0, len);
        if ((n = write(fd, &stats, len)) == -1)
                err(1, "write");
        if ((size_t)n != len)
                errx(1, "write not %zu: %zd", len, n);
        if (close(fd) == -1)
                err(1, "close read");

        /*
         * Map file on NFS client and write sysctl net.inet.tcp.stats into it.
         */
        snprintf(path, sizeof(path), "%s/%s", CLIENT, FILE);
        if ((fd = open(path, O_RDWR)) == -1)
                err(1, "open mmap '%s'", path);
        p = mmap(NULL, len, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
        if (p == MAP_FAILED)
                err(1, "mmap");
        if (sysctl(mib, miblen, p, &len, NULL, 0) == -1)
                err(1, "sysctl get stat");
        if (len != sizeof(struct tcpstat))
                errx(1, "len not %zu: %zu", sizeof(struct tcpstat), len);
        if (close(fd) == -1)
                err(1, "close mmap");

        /*
         * Read file from NFS server.
         */
        snprintf(path, sizeof(path), "%s/%s", SERVER, FILE);
        if ((fd = open(path, O_RDONLY)) == -1)
                err(1, "open read '%s'", path);
        if ((n = read(fd, &stats, len)) == -1)
                err(1, "read");
        if ((size_t)n != len)
                errx(1, "read not %zu: %zd", len, n);
        if (close(fd) == -1)
                err(1, "close read");

        return (0);
}