/*-
 * Copyright (c) 2006-2009 Sam Leffler, Errno Consulting
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer,
 *    without modification.
 * 2. Redistributions in binary form must reproduce at minimum a disclaimer
 *    similar to the "NO WARRANTY" disclaimer below ("Disclaimer") and any
 *    redistribution must be conditioned upon including a substantially
 *    similar Disclaimer requirement for further binary redistribution.
 *
 * NO WARRANTY
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF NONINFRINGEMENT, MERCHANTIBILITY
 * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
 * THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY,
 * OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
 * IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
 * THE POSSIBILITY OF SUCH DAMAGES.
 */

/*
 * Test app to demonstrate how to handle dynamic WDS links:
 * o monitor 802.11 events for wds discovery events
 * o create wds vap's in response to wds discovery events
 *   and launch a script to handle adding the vap to the
 *   bridge, etc.
 * o destroy wds vap's when station leaves
 */
#include <sys/param.h>
#include <sys/file.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <sys/sysctl.h>
#include <sys/types.h>

#include <net/if.h>
#include "net/if_media.h"
#include <net/route.h>
#include <net/if_dl.h>
#include <netinet/in.h>
#include <netinet/if_ether.h>
#include "net80211/ieee80211_ioctl.h"
#include "net80211/ieee80211_freebsd.h"
#include <arpa/inet.h>
#include <netdb.h>

#include <net/if.h>
#include <net/if_types.h>

#include <ctype.h>
#include <err.h>
#include <errno.h>
#include <paths.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sysexits.h>
#include <syslog.h>
#include <unistd.h>
#include <ifaddrs.h>
#include <libutil.h>

#define IEEE80211_ADDR_EQ(a1,a2)        (memcmp(a1,a2,IEEE80211_ADDR_LEN) == 0)
#define IEEE80211_ADDR_COPY(dst,src)    memcpy(dst,src,IEEE80211_ADDR_LEN)

struct wds {
        struct wds *next;
        uint8_t bssid[IEEE80211_ADDR_LEN];      /* bssid of associated sta */
        char    ifname[IFNAMSIZ];               /* vap interface name */
};
static struct wds *wds;

static  const char *script = NULL;
static  char **ifnets;
static  int nifnets = 0;
static  int discover_on_join = 0;

static  void scanforvaps(int s);
static  void handle_rtmsg(struct rt_msghdr *rtm, ssize_t msglen);
static  void wds_discovery(const char *ifname,
                const uint8_t bssid[IEEE80211_ADDR_LEN]);
static  void wds_destroy(const char *ifname);
static  void wds_leave(const uint8_t bssid[IEEE80211_ADDR_LEN]);
static  int wds_vap_create(const char *ifname, uint8_t macaddr[ETHER_ADDR_LEN],
            struct wds *);
static  int wds_vap_destroy(const char *ifname);

static void
usage(const char *progname)
{
        fprintf(stderr, "usage: %s [-efjtv] [-P pidfile] [-s <set_scriptname>] [ifnet0 ... | any]\n",
                progname);
        exit(-1);
}

int
main(int argc, char *argv[])
{
        const char *progname = argv[0];
        const char *pidfile = NULL;
        struct pidfh *pfh = NULL;
        int s, c, logmask, bg = 1;
        char msg[2048];
        int log_stderr = 0;
        pid_t otherpid;

        logmask = LOG_UPTO(LOG_INFO);
        while ((c = getopt(argc, argv, "efjP:s:tv")) != -1)
                switch (c) {
                case 'e':
                        log_stderr = LOG_PERROR;
                        break;
                case 'f':
                        bg = 0;
                        break;
                case 'j':
                        discover_on_join = 1;
                        break;
                case 'P':
                        pidfile = optarg;
                        break;
                case 's':
                        script = optarg;
                        break;
                case 't':
                        logmask = LOG_UPTO(LOG_ERR);
                        break;
                case 'v':
                        logmask = LOG_UPTO(LOG_DEBUG);
                        break;
                case '?':
                        usage(progname);
                        /*NOTREACHED*/
                }
        argc -= optind, argv += optind;
        if (argc == 0) {
                fprintf(stderr, "%s: no ifnet's specified to monitor\n",
                    progname);
                usage(progname);
        }
        ifnets = argv;
        nifnets = argc;

        if (pidfile != NULL) {
                pfh = pidfile_open(pidfile, 0600, &otherpid);
                if (pfh == NULL) {
                        if (errno == EEXIST)
                                errx(EXIT_FAILURE, "Daemon already running; pid: %jd.",
                                    (intmax_t)otherpid);

                        warn("Cannot open or create pidfile");
                }
        }

        s = socket(PF_ROUTE, SOCK_RAW, 0);
        if (s < 0)
                err(EX_OSERR, "socket");
        /*
         * Scan for inherited state.
         */
        scanforvaps(s);

        /* XXX what directory to work in? */
        if (bg && daemon(0, 0) < 0) {
                pidfile_remove(pfh);
                err(EX_OSERR, "daemon");
        }

        pidfile_write(pfh);

        openlog("wlanwds", log_stderr | LOG_PID | LOG_CONS, LOG_DAEMON);
        setlogmask(logmask);

        for (;;) {
                ssize_t n = read(s, msg, sizeof(msg));
                handle_rtmsg((struct rt_msghdr *)msg, n);
        }

        pidfile_remove(pfh);
        return 0;
}

static const char *
ether_sprintf(const uint8_t mac[IEEE80211_ADDR_LEN])
{
        static char buf[32];

        snprintf(buf, sizeof(buf), "%02x:%02x:%02x:%02x:%02x:%02x",
                mac[0], mac[1], mac[2], mac[3], mac[4], mac[5]);
        return buf;
}

/*
 * Fetch a vap's parent ifnet name.
 */
static int
getparent(const char *ifname, char parent[IFNAMSIZ+1])
{
        char oid[256];
        size_t parentlen;

        /* fetch parent interface name */
        snprintf(oid, sizeof(oid), "net.wlan.%s.%%parent", ifname+4);
        parentlen = IFNAMSIZ;
        if (sysctlbyname(oid, parent, &parentlen, NULL, 0) < 0)
                return -1;
        parent[parentlen] = '\0';
        return 0;
}

/*
 * Check if the specified ifnet is one we're supposed to monitor.
 * The ifnet is assumed to be a vap; we find it's parent and check
 * it against the set of ifnet's specified on the command line.
 *
 * TODO: extend this to also optionally allow the specific DWDS
 * VAP to be monitored, instead of assuming all VAPs on a parent
 * physical interface are being monitored by this instance of
 * wlanwds.
 */
static int
checkifnet(const char *ifname, int complain)
{
        char parent[256];
        int i;

        if (getparent(ifname, parent) < 0) {
                if (complain)
                        syslog(LOG_ERR,
                           "%s: no pointer to parent interface: %m", ifname);
                return 0;
        }

        for (i = 0; i < nifnets; i++)
                if (strcasecmp(ifnets[i], "any") == 0 ||
                    strcmp(ifnets[i], parent) == 0)
                        return 1;
        syslog(LOG_DEBUG, "%s: parent %s not being monitored", ifname, parent);
        return 0;
}

/*
 * Return 1 if the specified ifnet is a WDS vap.
 */
static int
iswdsvap(int s, const char *ifname)
{
        struct ifmediareq ifmr;

        memset(&ifmr, 0, sizeof(ifmr));
        strncpy(ifmr.ifm_name, ifname, sizeof(ifmr.ifm_name));
        if (ioctl(s, SIOCGIFMEDIA, (caddr_t)&ifmr) < 0)
                err(-1, "%s: cannot get media", ifname);
        return (ifmr.ifm_current & IFM_IEEE80211_WDS) != 0;
}

/*
 * Fetch the bssid for an ifnet.  The caller is assumed
 * to have already verified this is possible.
 */
static void
getbssid(int s, const char *ifname, uint8_t bssid[IEEE80211_ADDR_LEN])
{
        struct ieee80211req ireq;

        memset(&ireq, 0, sizeof(ireq));
        strncpy(ireq.i_name, ifname, sizeof(ireq.i_name));
        ireq.i_type = IEEE80211_IOC_BSSID;
        ireq.i_data = bssid;
        ireq.i_len = IEEE80211_ADDR_LEN;
        if (ioctl(s, SIOCG80211, &ireq) < 0)
                err(-1, "%s: cannot fetch bssid", ifname);
}

/*
 * Fetch the mac address configured for a given ifnet.
 * (Note - the current link level address, NOT hwaddr.)
 *
 * This is currently, sigh, O(n) because there's no current kernel
 * API that will do it for a single interface.
 *
 * Return 0 if successful, -1 if failure.
 */
static int
getlladdr(const char *ifname, uint8_t macaddr[ETHER_ADDR_LEN])
{
        struct ifaddrs *ifap, *ifa;
        struct sockaddr_dl *sdl;

        if (getifaddrs(&ifap) < 0) {
                warn("%s: getifaddrs", __func__);
                return (-1);
        }

        /* Look for a matching interface */
        for (ifa = ifap; ifa != NULL; ifa = ifa->ifa_next) {
                if (strcmp(ifname, ifa->ifa_name) != 0)
                        continue;

                /* Found it - check if there's an ifa_addr */
                if (ifa->ifa_addr == NULL) {
                        syslog(LOG_CRIT, "%s: ifname %s; ifa_addr is NULL\n",
                            __func__, ifname);
                        goto err;
                }

                /* Check address family */
                sdl = (struct sockaddr_dl *)(void *)ifa->ifa_addr;
                if (sdl->sdl_type != IFT_ETHER) {
                        syslog(LOG_CRIT, "%s: %s: unknown aftype (%d)\n",
                            __func__,
                            ifname,
                            sdl->sdl_type);
                        goto err;
                }
                if (sdl->sdl_alen != ETHER_ADDR_LEN) {
                        syslog(LOG_CRIT, "%s: %s: aflen too short (%d)\n",
                            __func__,
                            ifname,
                            sdl->sdl_alen);
                        goto err;
                }

                /* Ok, found it */
                memcpy(macaddr, (void *) LLADDR(sdl), ETHER_ADDR_LEN);
                goto ok;
        }
        syslog(LOG_CRIT, "%s: couldn't find ifname %s\n", __func__, ifname);
        /* FALLTHROUGH */
err:
        freeifaddrs(ifap);
        return (-1);

ok:
        freeifaddrs(ifap);
        return (0);
}

/*
 * Scan the system for WDS vaps associated with the ifnet's we're
 * supposed to monitor.  Any vaps are added to our internal table
 * so we can find them (and destroy them) on station leave.
 */
static void
scanforvaps(int s)
{
        char ifname[IFNAMSIZ+1];
        uint8_t bssid[IEEE80211_ADDR_LEN];
        int i;

        /* XXX brutal; should just walk sysctl tree */
        for (i = 0; i < 128; i++) {
                snprintf(ifname, sizeof(ifname), "wlan%d", i);
                if (checkifnet(ifname, 0) && iswdsvap(s, ifname)) {
                        struct wds *p = malloc(sizeof(struct wds));
                        if (p == NULL)
                                err(-1, "%s: malloc failed", __func__);
                        strlcpy(p->ifname, ifname, IFNAMSIZ);
                        getbssid(s, ifname, p->bssid);
                        p->next = wds;
                        wds = p;

                        syslog(LOG_INFO, "[%s] discover wds vap %s",
                            ether_sprintf(bssid), ifname);
                }
        }
}

/*
 * Process a routing socket message.  We handle messages related
 * to dynamic WDS:
 * o on WDS discovery (rx of a 4-address frame with DWDS enabled)
 *   we create a WDS vap for the specified mac address
 * o on station leave we destroy any associated WDS vap
 * o on ifnet destroy we update state if this is manual destroy of
 *   a WDS vap in our table
 * o if the -j option is supplied on the command line we create
 *   WDS vaps on station join/rejoin, this is useful for some setups
 *   where a WDS vap is required for 4-address traffic to flow
 */
static void
handle_rtmsg(struct rt_msghdr *rtm, ssize_t msglen)
{
        struct if_announcemsghdr *ifan;

        (void) msglen; /* UNUSED */

        if (rtm->rtm_version != RTM_VERSION) {
                syslog(LOG_ERR, "routing message version %d not understood",
                    rtm->rtm_version);
                return;
        }
        switch (rtm->rtm_type) {
        case RTM_IFANNOUNCE:
                ifan = (struct if_announcemsghdr *)rtm;
                switch (ifan->ifan_what) {
                case IFAN_ARRIVAL:
                        syslog(LOG_DEBUG,
                            "RTM_IFANNOUNCE: if# %d, what: arrival",
                            ifan->ifan_index);
                        break;
                case IFAN_DEPARTURE:
                        syslog(LOG_DEBUG,
                            "RTM_IFANNOUNCE: if# %d, what: departure",
                            ifan->ifan_index);
                        /* NB: ok to call w/ unmonitored ifnets */
                        wds_destroy(ifan->ifan_name);
                        break;
                }
                break;
        case RTM_IEEE80211:
#define V(type) ((struct type *)(&ifan[1]))
                ifan = (struct if_announcemsghdr *)rtm;
                switch (ifan->ifan_what) {
                case RTM_IEEE80211_DISASSOC:
                        if (!discover_on_join)
                                break;
                        /* fall thru... */
                case RTM_IEEE80211_LEAVE:
                        if (!checkifnet(ifan->ifan_name, 1))
                                break;
                        syslog(LOG_INFO, "[%s] station leave",
                            ether_sprintf(V(ieee80211_leave_event)->iev_addr));
                        wds_leave(V(ieee80211_leave_event)->iev_addr);
                        break;
                case RTM_IEEE80211_JOIN:
                case RTM_IEEE80211_REJOIN:
                case RTM_IEEE80211_ASSOC:
                case RTM_IEEE80211_REASSOC:
                        if (!discover_on_join)
                                break;
                        /* fall thru... */
                case RTM_IEEE80211_WDS:
                        syslog(LOG_INFO, "[%s] wds discovery",
                            ether_sprintf(V(ieee80211_wds_event)->iev_addr));
                        if (!checkifnet(ifan->ifan_name, 1))
                                break;
                        wds_discovery(ifan->ifan_name,
                            V(ieee80211_wds_event)->iev_addr);
                        break;
                }
                break;
#undef V
        }
}

/*
 * Handle WDS discovery; create a WDS vap for the specified bssid.
 * If a vap already exists then do nothing (can happen when a flood
 * of 4-address frames causes multiple events to be queued before
 * we create a vap).
 */
static void
wds_discovery(const char *ifname, const uint8_t bssid[IEEE80211_ADDR_LEN])
{
        struct wds *p;
        char parent[256];
        char cmd[1024];
        uint8_t macaddr[ETHER_ADDR_LEN];
        int status;

        for (p = wds; p != NULL; p = p->next)
                if (IEEE80211_ADDR_EQ(p->bssid, bssid)) {
                        syslog(LOG_INFO, "[%s] wds vap already created (%s)",
                            ether_sprintf(bssid), ifname);
                        return;
                }
        if (getparent(ifname, parent) < 0) {
                syslog(LOG_ERR, "%s: no pointer to parent interface: %m",
                    ifname);
                return;
        }

        if (getlladdr(ifname, macaddr) < 0) {
                syslog(LOG_ERR, "%s: couldn't get lladdr for parent interface: %m",
                    ifname);
                return;
        }

        p = malloc(sizeof(struct wds));
        if (p == NULL) {
                syslog(LOG_ERR, "%s: malloc failed: %m", __func__);
                return;
        }
        IEEE80211_ADDR_COPY(p->bssid, bssid);
        if (wds_vap_create(parent, macaddr, p) < 0) {
                free(p);
                return;
        }
        /*
         * Add to table and launch setup script.
         */
        p->next = wds;
        wds = p;
        syslog(LOG_INFO, "[%s] create wds vap %s, parent %s (%s)",
            ether_sprintf(bssid),
            p->ifname,
            ifname,
            parent);
        if (script != NULL) {
                snprintf(cmd, sizeof(cmd), "%s %s", script, p->ifname);
                status = system(cmd);
                if (status)
                        syslog(LOG_ERR, "vap setup script %s exited with "
                            "status %d", script, status);
        }
}

/* 
 * Destroy a WDS vap (if known).
 */
static void
wds_destroy(const char *ifname)
{
        struct wds *p, **pp;

        for (pp = &wds; (p = *pp) != NULL; pp = &p->next)
                if (strncmp(p->ifname, ifname, IFNAMSIZ) == 0)
                        break;
        if (p != NULL) {
                *pp = p->next;
                /* NB: vap already destroyed */
                free(p);
                return;
        }
}

/*
 * Handle a station leave event; destroy any associated WDS vap.
 */
static void
wds_leave(const uint8_t bssid[IEEE80211_ADDR_LEN])
{
        struct wds *p, **pp;

        for (pp = &wds; (p = *pp) != NULL; pp = &p->next)
                if (IEEE80211_ADDR_EQ(p->bssid, bssid))
                        break;
        if (p != NULL) {
                *pp = p->next;
                if (wds_vap_destroy(p->ifname) >= 0)
                        syslog(LOG_INFO, "[%s] wds vap %s destroyed",
                            ether_sprintf(bssid), p->ifname);
                free(p);
        }
}

static int
wds_vap_create(const char *parent, uint8_t macaddr[ETHER_ADDR_LEN],
    struct wds *p)
{
        struct ieee80211_clone_params cp;
        struct ifreq ifr;
        int s, status;
        char bssid_str[32], macaddr_str[32];

        memset(&cp, 0, sizeof(cp));

        /* Parent interface */
        strncpy(cp.icp_parent, parent, IFNAMSIZ);

        /* WDS interface */
        cp.icp_opmode = IEEE80211_M_WDS;

        /* BSSID for the current node */
        IEEE80211_ADDR_COPY(cp.icp_bssid, p->bssid);

        /*
         * Set the MAC address to match the actual interface
         * that we received the discovery event from.
         * That way we can run WDS on any VAP rather than
         * only the first VAP and then correctly set the
         * MAC address.
         */
        cp.icp_flags |= IEEE80211_CLONE_MACADDR;
        IEEE80211_ADDR_COPY(cp.icp_macaddr, macaddr);

        memset(&ifr, 0, sizeof(ifr));
        strncpy(ifr.ifr_name, "wlan", IFNAMSIZ);
        ifr.ifr_data = (void *) &cp;

        status = -1;
        s = socket(AF_INET, SOCK_DGRAM, 0);
        if (s >= 0) {
                if (ioctl(s, SIOCIFCREATE2, &ifr) >= 0) {
                        strlcpy(p->ifname, ifr.ifr_name, IFNAMSIZ);
                        status = 0;
                } else {
                        syslog(LOG_ERR, "SIOCIFCREATE2("
                            "mode %u flags 0x%x parent %s bssid %s macaddr %s): %m",
                            cp.icp_opmode, cp.icp_flags, parent,
                            ether_ntoa_r((void *) cp.icp_bssid, bssid_str),
                            ether_ntoa_r((void *) cp.icp_macaddr, macaddr_str));
                }
                close(s);
        } else
                syslog(LOG_ERR, "socket(SOCK_DRAGM): %m");
        return status;
}

static int
wds_vap_destroy(const char *ifname)
{
        struct ieee80211req ifr;
        int s, status;

        s = socket(AF_INET, SOCK_DGRAM, 0);
        if (s < 0) {
                syslog(LOG_ERR, "socket(SOCK_DRAGM): %m");
                return -1;
        }
        memset(&ifr, 0, sizeof(ifr));
        strncpy(ifr.i_name, ifname, IFNAMSIZ);
        if (ioctl(s, SIOCIFDESTROY, &ifr) < 0) {
                syslog(LOG_ERR, "ioctl(SIOCIFDESTROY): %m");
                status = -1;
        } else
                status = 0;
        close(s);
        return status;
}