wps_upnp_ssdp.c

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/*
 * UPnP SSDP for WPS
 * Copyright (c) 2000-2003 Intel Corporation
 * Copyright (c) 2006-2007 Sony Corporation
 * Copyright (c) 2008-2009 Atheros Communications
 * Copyright (c) 2009, Jouni Malinen <j@w1.fi>
 *
 * See wps_upnp.c for more details on licensing and code history.
 */

#include "includes.h"

#include <fcntl.h>
#include <sys/ioctl.h>
#include <net/route.h>

#include "common.h"
#include "uuid.h"
#include "eloop.h"
#include "wps.h"
#include "wps_upnp.h"
#include "wps_upnp_i.h"

#define UPNP_CACHE_SEC (UPNP_CACHE_SEC_MIN + 1) /* cache time we use */
#define UPNP_CACHE_SEC_MIN 1800 /* min cachable time per UPnP standard */
#define UPNP_ADVERTISE_REPEAT 2 /* no more than 3 */
#define MAX_MSEARCH 20          /* max simultaneous M-SEARCH replies ongoing */
#define SSDP_TARGET  "239.0.0.0"
#define SSDP_NETMASK "255.0.0.0"


/* Check tokens for equality, where tokens consist of letters, digits,
 * underscore and hyphen, and are matched case insensitive.
 */
static int token_eq(const char *s1, const char *s2)
{
        int c1;
        int c2;
        int end1 = 0;
        int end2 = 0;
        for (;;) {
                c1 = *s1++;
                c2 = *s2++;
                if (isalpha(c1) && isupper(c1))
                        c1 = tolower(c1);
                if (isalpha(c2) && isupper(c2))
                        c2 = tolower(c2);
                end1 = !(isalnum(c1) || c1 == '_' || c1 == '-');
                end2 = !(isalnum(c2) || c2 == '_' || c2 == '-');
                if (end1 || end2 || c1 != c2)
                        break;
        }
        return end1 && end2; /* reached end of both words? */
}


/* Return length of token (see above for definition of token) */
static int token_length(const char *s)
{
        const char *begin = s;
        for (;; s++) {
                int c = *s;
                int end = !(isalnum(c) || c == '_' || c == '-');
                if (end)
                        break;
        }
        return s - begin;
}


/* return length of interword separation.
 * This accepts only spaces/tabs and thus will not traverse a line
 * or buffer ending.
 */
static int word_separation_length(const char *s)
{
        const char *begin = s;
        for (;; s++) {
                int c = *s;
                if (c == ' ' || c == '\t')
                        continue;
                break;
        }
        return s - begin;
}


/* No. of chars through (including) end of line */
static int line_length(const char *l)
{
        const char *lp = l;
        while (*lp && *lp != '\n')
                lp++;
        if (*lp == '\n')
                lp++;
        return lp - l;
}


/* No. of chars excluding trailing whitespace */
static int line_length_stripped(const char *l)
{
        const char *lp = l + line_length(l);
        while (lp > l && !isgraph(lp[-1]))
                lp--;
        return lp - l;
}


static int str_starts(const char *str, const char *start)
{
        return os_strncmp(str, start, os_strlen(start)) == 0;
}


/***************************************************************************
 * Advertisements.
 * These are multicast to the world to tell them we are here.
 * The individual packets are spread out in time to limit loss,
 * and then after a much longer period of time the whole sequence
 * is repeated again (for NOTIFYs only).
 **************************************************************************/

static struct wpabuf *
next_advertisement(struct upnp_wps_device_sm *sm,
                   struct advertisement_state_machine *a, int *islast)
{
        struct wpabuf *msg;
        char *NTString = "";
        char uuid_string[80];

        *islast = 0;
        uuid_bin2str(sm->wps->uuid, uuid_string, sizeof(uuid_string));
        msg = wpabuf_alloc(800); /* more than big enough */
        if (msg == NULL)
                goto fail;
        switch (a->type) {
        case ADVERTISE_UP:
        case ADVERTISE_DOWN:
                NTString = "NT";
                wpabuf_put_str(msg, "NOTIFY * HTTP/1.1\r\n");
                wpabuf_printf(msg, "HOST: %s:%d\r\n",
                              UPNP_MULTICAST_ADDRESS, UPNP_MULTICAST_PORT);
                wpabuf_printf(msg, "CACHE-CONTROL: max-age=%d\r\n",
                              UPNP_CACHE_SEC);
                wpabuf_printf(msg, "NTS: %s\r\n",
                              (a->type == ADVERTISE_UP ?
                               "ssdp:alive" : "ssdp:byebye"));
                break;
        case MSEARCH_REPLY:
                NTString = "ST";
                wpabuf_put_str(msg, "HTTP/1.1 200 OK\r\n");
                wpabuf_printf(msg, "CACHE-CONTROL: max-age=%d\r\n",
                              UPNP_CACHE_SEC);

                wpabuf_put_str(msg, "DATE: ");
                format_date(msg);
                wpabuf_put_str(msg, "\r\n");

                wpabuf_put_str(msg, "EXT:\r\n");
                break;
        }

        if (a->type != ADVERTISE_DOWN) {
                /* Where others may get our XML files from */
                wpabuf_printf(msg, "LOCATION: http://%s:%d/%s\r\n",
                              sm->ip_addr_text, sm->web_port,
                              UPNP_WPS_DEVICE_XML_FILE);
        }

        /* The SERVER line has three comma-separated fields:
         *      operating system / version
         *      upnp version
         *      software package / version
         * However, only the UPnP version is really required, the
         * others can be place holders... for security reasons
         * it is better to NOT provide extra information.
         */
        wpabuf_put_str(msg, "SERVER: Unspecified, UPnP/1.0, Unspecified\r\n");

        switch (a->state / UPNP_ADVERTISE_REPEAT) {
        case 0:
                wpabuf_printf(msg, "%s: upnp:rootdevice\r\n", NTString);
                wpabuf_printf(msg, "USN: uuid:%s::upnp:rootdevice\r\n",
                              uuid_string);
                break;
        case 1:
                wpabuf_printf(msg, "%s: uuid:%s\r\n", NTString, uuid_string);
                wpabuf_printf(msg, "USN: uuid:%s\r\n", uuid_string);
                break;
        case 2:
                wpabuf_printf(msg, "%s: urn:schemas-wifialliance-org:device:"
                              "WFADevice:1\r\n", NTString);
                wpabuf_printf(msg, "USN: uuid:%s::urn:schemas-wifialliance-"
                              "org:device:WFADevice:1\r\n", uuid_string);
                break;
        case 3:
                wpabuf_printf(msg, "%s: urn:schemas-wifialliance-org:service:"
                              "WFAWLANConfig:1\r\n", NTString);
                wpabuf_printf(msg, "USN: uuid:%s::urn:schemas-wifialliance-"
                              "org:service:WFAWLANConfig:1\r\n", uuid_string);
                break;
        }
        wpabuf_put_str(msg, "\r\n");

        if (a->state + 1 >= 4 * UPNP_ADVERTISE_REPEAT)
                *islast = 1;

        return msg;

fail:
        wpabuf_free(msg);
        return NULL;
}


static void advertisement_state_machine_handler(void *eloop_data,
                                                void *user_ctx);


void advertisement_state_machine_stop(struct upnp_wps_device_sm *sm,
                                      int send_byebye)
{
        struct advertisement_state_machine *a = &sm->advertisement;
        int islast = 0;
        struct wpabuf *msg;
        struct sockaddr_in dest;

        eloop_cancel_timeout(advertisement_state_machine_handler, NULL, sm);
        if (!send_byebye || sm->multicast_sd < 0)
                return;

        a->type = ADVERTISE_DOWN;
        a->state = 0;

        os_memset(&dest, 0, sizeof(dest));
        dest.sin_family = AF_INET;
        dest.sin_addr.s_addr = inet_addr(UPNP_MULTICAST_ADDRESS);
        dest.sin_port = htons(UPNP_MULTICAST_PORT);

        while (!islast) {
                msg = next_advertisement(sm, a, &islast);
                if (msg == NULL)
                        break;
                if (sendto(sm->multicast_sd, wpabuf_head(msg), wpabuf_len(msg),
                           0, (struct sockaddr *) &dest, sizeof(dest)) < 0) {
                        wpa_printf(MSG_INFO, "WPS UPnP: Advertisement sendto "
                                   "failed: %d (%s)", errno, strerror(errno));
                }
                wpabuf_free(msg);
                a->state++;
        }
}


static void advertisement_state_machine_handler(void *eloop_data,
                                                void *user_ctx)
{
        struct upnp_wps_device_sm *sm = user_ctx;
        struct advertisement_state_machine *a = &sm->advertisement;
        struct wpabuf *msg;
        int next_timeout_msec = 100;
        int next_timeout_sec = 0;
        struct sockaddr_in dest;
        int islast = 0;

        /*
         * Each is sent twice (in case lost) w/ 100 msec delay between;
         * spec says no more than 3 times.
         * One pair for rootdevice, one pair for uuid, and a pair each for
         * each of the two urns.
         * The entire sequence must be repeated before cache control timeout
         * (which  is min  1800 seconds),
         * recommend random portion of half of the advertised cache control age
         * to ensure against loss... perhaps 1800/4 + rand*1800/4 ?
         * Delay random interval < 100 msec prior to initial sending.
         * TTL of 4
         */

        wpa_printf(MSG_MSGDUMP, "WPS UPnP: Advertisement state=%d", a->state);
        msg = next_advertisement(sm, a, &islast);
        if (msg == NULL)
                return;

        os_memset(&dest, 0, sizeof(dest));
        dest.sin_family = AF_INET;
        dest.sin_addr.s_addr = inet_addr(UPNP_MULTICAST_ADDRESS);
        dest.sin_port = htons(UPNP_MULTICAST_PORT);

        if (sendto(sm->multicast_sd, wpabuf_head(msg), wpabuf_len(msg), 0,
                   (struct sockaddr *) &dest, sizeof(dest)) == -1) {
                wpa_printf(MSG_ERROR, "WPS UPnP: Advertisement sendto failed:"
                           "%d (%s)", errno, strerror(errno));
                next_timeout_msec = 0;
                next_timeout_sec = 10; /* ... later */
        } else if (islast) {
                a->state = 0; /* wrap around */
                if (a->type == ADVERTISE_DOWN) {
                        wpa_printf(MSG_DEBUG, "WPS UPnP: ADVERTISE_DOWN->UP");
                        a->type = ADVERTISE_UP;
                        /* do it all over again right away */
                } else {
                        u16 r;
                        /*
                         * Start over again after a long timeout
                         * (see notes above)
                         */
                        next_timeout_msec = 0;
                        os_get_random((void *) &r, sizeof(r));
                        next_timeout_sec = UPNP_CACHE_SEC / 4 +
                                (((UPNP_CACHE_SEC / 4) * r) >> 16);
                        sm->advertise_count++;
                        wpa_printf(MSG_DEBUG, "WPS UPnP: ADVERTISE_UP (#%u); "
                                   "next in %d sec",
                                   sm->advertise_count, next_timeout_sec);
                }
        } else {
                a->state++;
        }

        wpabuf_free(msg);

        eloop_register_timeout(next_timeout_sec, next_timeout_msec,
                               advertisement_state_machine_handler, NULL, sm);
}


int advertisement_state_machine_start(struct upnp_wps_device_sm *sm)
{
        struct advertisement_state_machine *a = &sm->advertisement;
        int next_timeout_msec;

        advertisement_state_machine_stop(sm, 0);

        /*
         * Start out advertising down, this automatically switches
         * to advertising up which signals our restart.
         */
        a->type = ADVERTISE_DOWN;
        a->state = 0;
        /* (other fields not used here) */

        /* First timeout should be random interval < 100 msec */
        next_timeout_msec = (100 * (os_random() & 0xFF)) >> 8;
        return eloop_register_timeout(0, next_timeout_msec,
                                      advertisement_state_machine_handler,
                                      NULL, sm);
}


/***************************************************************************
 * M-SEARCH replies
 * These are very similar to the multicast advertisements, with some
 * small changes in data content; and they are sent (UDP) to a specific
 * unicast address instead of multicast.
 * They are sent in response to a UDP M-SEARCH packet.
 **************************************************************************/

void msearchreply_state_machine_stop(struct advertisement_state_machine *a)
{
        wpa_printf(MSG_DEBUG, "WPS UPnP: M-SEARCH stop");
        dl_list_del(&a->list);
        os_free(a);
}


static void msearchreply_state_machine_handler(void *eloop_data,
                                               void *user_ctx)
{
        struct advertisement_state_machine *a = user_ctx;
        struct upnp_wps_device_sm *sm = eloop_data;
        struct wpabuf *msg;
        int next_timeout_msec = 100;
        int next_timeout_sec = 0;
        int islast = 0;

        /*
         * Each response is sent twice (in case lost) w/ 100 msec delay
         * between; spec says no more than 3 times.
         * One pair for rootdevice, one pair for uuid, and a pair each for
         * each of the two urns.
         */

        /* TODO: should only send the requested response types */

        wpa_printf(MSG_MSGDUMP, "WPS UPnP: M-SEARCH reply state=%d (%s:%d)",
                   a->state, inet_ntoa(a->client.sin_addr),
                   ntohs(a->client.sin_port));
        msg = next_advertisement(sm, a, &islast);
        if (msg == NULL)
                return;

        /*
         * Send it on the multicast socket to avoid having to set up another
         * socket.
         */
        if (sendto(sm->multicast_sd, wpabuf_head(msg), wpabuf_len(msg), 0,
                   (struct sockaddr *) &a->client, sizeof(a->client)) < 0) {
                wpa_printf(MSG_DEBUG, "WPS UPnP: M-SEARCH reply sendto "
                           "errno %d (%s) for %s:%d",
                           errno, strerror(errno),
                           inet_ntoa(a->client.sin_addr),
                           ntohs(a->client.sin_port));
                /* Ignore error and hope for the best */
        }
        wpabuf_free(msg);
        if (islast) {
                wpa_printf(MSG_DEBUG, "WPS UPnP: M-SEARCH reply done");
                msearchreply_state_machine_stop(a);
                return;
        }
        a->state++;

        wpa_printf(MSG_MSGDUMP, "WPS UPnP: M-SEARCH reply in %d.%03d sec",
                   next_timeout_sec, next_timeout_msec);
        eloop_register_timeout(next_timeout_sec, next_timeout_msec,
                               msearchreply_state_machine_handler, sm, a);
}


static void msearchreply_state_machine_start(struct upnp_wps_device_sm *sm,
                                             struct sockaddr_in *client,
                                             int mx)
{
        struct advertisement_state_machine *a;
        int next_timeout_sec;
        int next_timeout_msec;
        int replies;

        replies = dl_list_len(&sm->msearch_replies);
        wpa_printf(MSG_DEBUG, "WPS UPnP: M-SEARCH reply start (%d "
                   "outstanding)", replies);
        if (replies >= MAX_MSEARCH) {
                wpa_printf(MSG_INFO, "WPS UPnP: Too many outstanding "
                           "M-SEARCH replies");
                return;
        }

        a = os_zalloc(sizeof(*a));
        if (a == NULL)
                return;
        a->type = MSEARCH_REPLY;
        a->state = 0;
        os_memcpy(&a->client, client, sizeof(*client));
        /* Wait time depending on MX value */
        next_timeout_msec = (1000 * mx * (os_random() & 0xFF)) >> 8;
        next_timeout_sec = next_timeout_msec / 1000;
        next_timeout_msec = next_timeout_msec % 1000;
        if (eloop_register_timeout(next_timeout_sec, next_timeout_msec,
                                   msearchreply_state_machine_handler, sm,
                                   a)) {
                /* No way to recover (from malloc failure) */
                goto fail;
        }
        /* Remember for future cleanup */
        dl_list_add(&sm->msearch_replies, &a->list);
        return;

fail:
        wpa_printf(MSG_INFO, "WPS UPnP: M-SEARCH reply failure!");
        eloop_cancel_timeout(msearchreply_state_machine_handler, sm, a);
        os_free(a);
}


static void ssdp_parse_msearch(struct upnp_wps_device_sm *sm,
                               struct sockaddr_in *client, const char *data)
{
#ifndef CONFIG_NO_STDOUT_DEBUG
        const char *start = data;
#endif /* CONFIG_NO_STDOUT_DEBUG */
        const char *end;
        int got_host = 0;
        int got_st = 0, st_match = 0;
        int got_man = 0;
        int got_mx = 0;
        int mx = 0;

        /*
         * Skip first line M-SEARCH * HTTP/1.1
         * (perhaps we should check remainder of the line for syntax)
         */
        data += line_length(data);

        /* Parse remaining lines */
        for (; *data != '\0'; data += line_length(data)) {
                end = data + line_length_stripped(data);
                if (token_eq(data, "host")) {
                        /* The host line indicates who the packet
                         * is addressed to... but do we really care?
                         * Note that Microsoft sometimes does funny
                         * stuff with the HOST: line.
                         */
#if 0   /* could be */
                        data += token_length(data);
                        data += word_separation_length(data);
                        if (*data != ':')
                                goto bad;
                        data++;
                        data += word_separation_length(data);
                        /* UPNP_MULTICAST_ADDRESS */
                        if (!str_starts(data, "239.255.255.250"))
                                goto bad;
                        data += os_strlen("239.255.255.250");
                        if (*data == ':') {
                                if (!str_starts(data, ":1900"))
                                        goto bad;
                        }
#endif  /* could be */
                        got_host = 1;
                        continue;
                } else if (token_eq(data, "st")) {
                        /* There are a number of forms; we look
                         * for one that matches our case.
                         */
                        got_st = 1;
                        data += token_length(data);
                        data += word_separation_length(data);
                        if (*data != ':')
                                continue;
                        data++;
                        data += word_separation_length(data);
                        if (str_starts(data, "ssdp:all")) {
                                st_match = 1;
                                continue;
                        }
                        if (str_starts(data, "upnp:rootdevice")) {
                                st_match = 1;
                                continue;
                        }
                        if (str_starts(data, "uuid:")) {
                                char uuid_string[80];
                                data += os_strlen("uuid:");
                                uuid_bin2str(sm->wps->uuid, uuid_string,
                                             sizeof(uuid_string));
                                if (str_starts(data, uuid_string))
                                        st_match = 1;
                                continue;
                        }
#if 0
                        /* FIX: should we really reply to IGD string? */
                        if (str_starts(data, "urn:schemas-upnp-org:device:"
                                       "InternetGatewayDevice:1")) {
                                st_match = 1;
                                continue;
                        }
#endif
                        if (str_starts(data, "urn:schemas-wifialliance-org:"
                                       "service:WFAWLANConfig:1")) {
                                st_match = 1;
                                continue;
                        }
                        if (str_starts(data, "urn:schemas-wifialliance-org:"
                                       "device:WFADevice:1")) {
                                st_match = 1;
                                continue;
                        }
                        continue;
                } else if (token_eq(data, "man")) {
                        data += token_length(data);
                        data += word_separation_length(data);
                        if (*data != ':')
                                continue;
                        data++;
                        data += word_separation_length(data);
                        if (!str_starts(data, "\"ssdp:discover\"")) {
                                wpa_printf(MSG_DEBUG, "WPS UPnP: Unexpected "
                                           "M-SEARCH man-field");
                                goto bad;
                        }
                        got_man = 1;
                        continue;
                } else if (token_eq(data, "mx")) {
                        data += token_length(data);
                        data += word_separation_length(data);
                        if (*data != ':')
                                continue;
                        data++;
                        data += word_separation_length(data);
                        mx = atol(data);
                        got_mx = 1;
                        continue;
                }
                /* ignore anything else */
        }
        if (!got_host || !got_st || !got_man || !got_mx || mx < 0) {
                wpa_printf(MSG_DEBUG, "WPS UPnP: Invalid M-SEARCH: %d %d %d "
                           "%d mx=%d", got_host, got_st, got_man, got_mx, mx);
                goto bad;
        }
        if (!st_match) {
                wpa_printf(MSG_DEBUG, "WPS UPnP: Ignored M-SEARCH (no ST "
                           "match)");
                return;
        }
        if (mx > 120)
                mx = 120; /* UPnP-arch-DeviceArchitecture, 1.2.3 */
        msearchreply_state_machine_start(sm, client, mx);
        return;

bad:
        wpa_printf(MSG_INFO, "WPS UPnP: Failed to parse M-SEARCH");
        wpa_printf(MSG_MSGDUMP, "WPS UPnP: M-SEARCH data:\n%s", start);
}


/* Listening for (UDP) discovery (M-SEARCH) packets */

void ssdp_listener_stop(struct upnp_wps_device_sm *sm)
{
        if (sm->ssdp_sd_registered) {
                eloop_unregister_sock(sm->ssdp_sd, EVENT_TYPE_READ);
                sm->ssdp_sd_registered = 0;
        }

        if (sm->ssdp_sd != -1) {
                close(sm->ssdp_sd);
                sm->ssdp_sd = -1;
        }

        eloop_cancel_timeout(msearchreply_state_machine_handler, sm,
                             ELOOP_ALL_CTX);
}


static void ssdp_listener_handler(int sd, void *eloop_ctx, void *sock_ctx)
{
        struct upnp_wps_device_sm *sm = sock_ctx;
        struct sockaddr_in addr; /* client address */
        socklen_t addr_len;
        int nread;
        char buf[MULTICAST_MAX_READ], *pos;

        addr_len = sizeof(addr);
        nread = recvfrom(sm->ssdp_sd, buf, sizeof(buf) - 1, 0,
                         (struct sockaddr *) &addr, &addr_len);
        if (nread <= 0)
                return;
        buf[nread] = '\0'; /* need null termination for algorithm */

        if (str_starts(buf, "NOTIFY ")) {
                /*
                 * Silently ignore NOTIFYs to avoid filling debug log with
                 * unwanted messages.
                 */
                return;
        }

        pos = os_strchr(buf, '\n');
        if (pos)
                *pos = '\0';
        wpa_printf(MSG_MSGDUMP, "WPS UPnP: Received SSDP packet from %s:%d: "
                   "%s", inet_ntoa(addr.sin_addr), ntohs(addr.sin_port), buf);
        if (pos)
                *pos = '\n';

        /* Parse first line */
        if (os_strncasecmp(buf, "M-SEARCH", os_strlen("M-SEARCH")) == 0 &&
            !isgraph(buf[strlen("M-SEARCH")])) {
                ssdp_parse_msearch(sm, &addr, buf);
                return;
        }

        /* Ignore anything else */
}


int ssdp_listener_open(void)
{
        struct sockaddr_in addr;
        struct ip_mreq mcast_addr;
        int on = 1;
        /* per UPnP spec, keep IP packet time to live (TTL) small */
        unsigned char ttl = 4;
        int sd;

        sd = socket(AF_INET, SOCK_DGRAM, 0);
        if (sd < 0)
                goto fail;
        if (fcntl(sd, F_SETFL, O_NONBLOCK) != 0)
                goto fail;
        if (setsockopt(sd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)))
                goto fail;
        os_memset(&addr, 0, sizeof(addr));
        addr.sin_family = AF_INET;
        addr.sin_addr.s_addr = htonl(INADDR_ANY);
        addr.sin_port = htons(UPNP_MULTICAST_PORT);
        if (bind(sd, (struct sockaddr *) &addr, sizeof(addr)))
                goto fail;
        os_memset(&mcast_addr, 0, sizeof(mcast_addr));
        mcast_addr.imr_interface.s_addr = htonl(INADDR_ANY);
        mcast_addr.imr_multiaddr.s_addr = inet_addr(UPNP_MULTICAST_ADDRESS);
        if (setsockopt(sd, IPPROTO_IP, IP_ADD_MEMBERSHIP,
                       (char *) &mcast_addr, sizeof(mcast_addr)))
                goto fail;
        if (setsockopt(sd, IPPROTO_IP, IP_MULTICAST_TTL,
                       &ttl, sizeof(ttl)))
                goto fail;

        return sd;

fail:
        if (sd >= 0)
                close(sd);
        return -1;
}


int ssdp_listener_start(struct upnp_wps_device_sm *sm)
{
        sm->ssdp_sd = ssdp_listener_open();

        if (eloop_register_sock(sm->ssdp_sd, EVENT_TYPE_READ,
                                ssdp_listener_handler, NULL, sm))
                goto fail;
        sm->ssdp_sd_registered = 1;
        return 0;

fail:
        /* Error */
        wpa_printf(MSG_ERROR, "WPS UPnP: ssdp_listener_start failed");
        ssdp_listener_stop(sm);
        return -1;
}


int add_ssdp_network(const char *net_if)
{
#ifdef __linux__
        int ret = -1;
        int sock = -1;
        struct rtentry rt;
        struct sockaddr_in *sin;

        if (!net_if)
                goto fail;

        os_memset(&rt, 0, sizeof(rt));
        sock = socket(AF_INET, SOCK_DGRAM, 0);
        if (sock < 0)
                goto fail;

        rt.rt_dev = (char *) net_if;
        sin = aliasing_hide_typecast(&rt.rt_dst, struct sockaddr_in);
        sin->sin_family = AF_INET;
        sin->sin_port = 0;
        sin->sin_addr.s_addr = inet_addr(SSDP_TARGET);
        sin = aliasing_hide_typecast(&rt.rt_genmask, struct sockaddr_in);
        sin->sin_family = AF_INET;
        sin->sin_port = 0;
        sin->sin_addr.s_addr = inet_addr(SSDP_NETMASK);
        rt.rt_flags = RTF_UP;
        if (ioctl(sock, SIOCADDRT, &rt) < 0) {
                if (errno == EPERM) {
                        wpa_printf(MSG_DEBUG, "add_ssdp_network: No "
                                   "permissions to add routing table entry");
                        /* Continue to allow testing as non-root */
                } else if (errno != EEXIST) {
                        wpa_printf(MSG_INFO, "add_ssdp_network() ioctl errno "
                                   "%d (%s)", errno, strerror(errno));
                        goto fail;
                }
        }

        ret = 0;

fail:
        if (sock >= 0)
                close(sock);

        return ret;
#else /* __linux__ */
        return 0;
#endif /* __linux__ */
}


int ssdp_open_multicast_sock(u32 ip_addr)
{
        int sd;
         /* per UPnP-arch-DeviceArchitecture, 1. Discovery, keep IP packet
          * time to live (TTL) small */
        unsigned char ttl = 4;

        sd = socket(AF_INET, SOCK_DGRAM, 0);
        if (sd < 0)
                return -1;

#if 0   /* maybe ok if we sometimes block on writes */
        if (fcntl(sd, F_SETFL, O_NONBLOCK) != 0)
                return -1;
#endif

        if (setsockopt(sd, IPPROTO_IP, IP_MULTICAST_IF,
                       &ip_addr, sizeof(ip_addr)))
                return -1;
        if (setsockopt(sd, IPPROTO_IP, IP_MULTICAST_TTL,
                       &ttl, sizeof(ttl)))
                return -1;

#if 0   /* not needed, because we don't receive using multicast_sd */
        {
                struct ip_mreq mreq;
                mreq.imr_multiaddr.s_addr = inet_addr(UPNP_MULTICAST_ADDRESS);
                mreq.imr_interface.s_addr = ip_addr;
                wpa_printf(MSG_DEBUG, "WPS UPnP: Multicast addr 0x%x if addr "
                           "0x%x",
                           mreq.imr_multiaddr.s_addr,
                           mreq.imr_interface.s_addr);
                if (setsockopt(sd, IPPROTO_IP, IP_ADD_MEMBERSHIP, &mreq,
                                sizeof(mreq))) {
                        wpa_printf(MSG_ERROR,
                                   "WPS UPnP: setsockopt "
                                   "IP_ADD_MEMBERSHIP errno %d (%s)",
                                   errno, strerror(errno));
                        return -1;
                }
        }
#endif  /* not needed */

        /*
         * TODO: What about IP_MULTICAST_LOOP? It seems to be on by default?
         * which aids debugging I suppose but isn't really necessary?
         */

        return sd;
}


int ssdp_open_multicast(struct upnp_wps_device_sm *sm)
{
        sm->multicast_sd = ssdp_open_multicast_sock(sm->ip_addr);
        if (sm->multicast_sd < 0)
                return -1;
        return 0;
}