- Copy stable/10 (r259064) to releng/10.0 as part of the

[FreeBSD/releng/10.0.git] / contrib / wpa / src / wps / wps_upnp.c

/*
 * UPnP WPS Device
 * Copyright (c) 2000-2003 Intel Corporation
 * Copyright (c) 2006-2007 Sony Corporation
 * Copyright (c) 2008-2009 Atheros Communications
 * Copyright (c) 2009-2010, Jouni Malinen <j@w1.fi>
 *
 * See below for more details on licensing and code history.
 */

/*
 * This has been greatly stripped down from the original file
 * (upnp_wps_device.c) by Ted Merrill, Atheros Communications
 * in order to eliminate use of the bulky libupnp library etc.
 *
 * History:
 * upnp_wps_device.c is/was a shim layer between wps_opt_upnp.c and
 * the libupnp library.
 * The layering (by Sony) was well done; only a very minor modification
 * to API of upnp_wps_device.c was required.
 * libupnp was found to be undesirable because:
 * -- It consumed too much code and data space
 * -- It uses multiple threads, making debugging more difficult
 *      and possibly reducing reliability.
 * -- It uses static variables and only supports one instance.
 * The shim and libupnp are here replaced by special code written
 * specifically for the needs of hostapd.
 * Various shortcuts can and are taken to keep the code size small.
 * Generally, execution time is not as crucial.
 *
 * BUGS:
 * -- UPnP requires that we be able to resolve domain names.
 * While uncommon, if we have to do it then it will stall the entire
 * hostapd program, which is bad.
 * This is because we use the standard linux getaddrinfo() function
 * which is syncronous.
 * An asyncronous solution would be to use the free "ares" library.
 * -- Does not have a robust output buffering scheme.  Uses a single
 * fixed size output buffer per TCP/HTTP connection, with possible (although
 * unlikely) possibility of overflow and likely excessive use of RAM.
 * A better solution would be to write the HTTP output as a buffered stream,
 * using chunking: (handle header specially, then) generate data with
 * a printf-like function into a buffer, catching buffer full condition,
 * then send it out surrounded by http chunking.
 * -- There is some code that could be separated out into the common
 * library to be shared with wpa_supplicant.
 * -- Needs renaming with module prefix to avoid polluting the debugger
 * namespace and causing possible collisions with other static fncs
 * and structure declarations when using the debugger.
 * -- The http error code generation is pretty bogus, hopefully no one cares.
 *
 * Author: Ted Merrill, Atheros Communications, based upon earlier work
 * as explained above and below.
 *
 * Copyright:
 * Copyright 2008 Atheros Communications.
 *
 * The original header (of upnp_wps_device.c) reads:
 *
 *  Copyright (c) 2006-2007 Sony Corporation. All Rights Reserved.
 *
 *  File Name: upnp_wps_device.c
 *  Description: EAP-WPS UPnP device source
 *
 *   Redistribution and use in source and binary forms, with or without
 *   modification, are permitted provided that the following conditions
 *   are met:
 *
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in
 *       the documentation and/or other materials provided with the
 *       distribution.
 *     * Neither the name of Sony Corporation nor the names of its
 *       contributors may be used to endorse or promote products derived
 *       from this software without specific prior written permission.
 *
 *   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 MERCHANTABILITY AND FITNESS FOR
 *   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 *   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 *   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 DAMAGE.
 *
 * Portions from Intel libupnp files, e.g. genlib/net/http/httpreadwrite.c
 * typical header:
 *
 * Copyright (c) 2000-2003 Intel Corporation
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * * Redistributions of source code must retain the above copyright notice,
 * this list of conditions and the following disclaimer.
 * * Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 * * Neither name of Intel Corporation nor the names of its contributors
 * may be used to endorse or promote products derived from this software
 * without specific prior written permission.
 *
 * 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 MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL INTEL OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 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 DAMAGE.
*/

/*
 * Overview of WPS over UPnP:
 *
 * UPnP is a protocol that allows devices to discover each other and control
 * each other. In UPnP terminology, a device is either a "device" (a server
 * that provides information about itself and allows itself to be controlled)
 * or a "control point" (a client that controls "devices") or possibly both.
 * This file implements a UPnP "device".
 *
 * For us, we use mostly basic UPnP discovery, but the control part of interest
 * is WPS carried via UPnP messages. There is quite a bit of basic UPnP
 * discovery to do before we can get to WPS, however.
 *
 * UPnP discovery begins with "devices" send out multicast UDP packets to a
 * certain fixed multicast IP address and port, and "control points" sending
 * out other such UDP packets.
 *
 * The packets sent by devices are NOTIFY packets (not to be confused with TCP
 * NOTIFY packets that are used later) and those sent by control points are
 * M-SEARCH packets. These packets contain a simple HTTP style header. The
 * packets are sent redundantly to get around packet loss. Devices respond to
 * M-SEARCH packets with HTTP-like UDP packets containing HTTP/1.1 200 OK
 * messages, which give similar information as the UDP NOTIFY packets.
 *
 * The above UDP packets advertise the (arbitrary) TCP ports that the
 * respective parties will listen to. The control point can then do a HTTP
 * SUBSCRIBE (something like an HTTP PUT) after which the device can do a
 * separate HTTP NOTIFY (also like an HTTP PUT) to do event messaging.
 *
 * The control point will also do HTTP GET of the "device file" listed in the
 * original UDP information from the device (see UPNP_WPS_DEVICE_XML_FILE
 * data), and based on this will do additional GETs... HTTP POSTs are done to
 * cause an action.
 *
 * Beyond some basic information in HTTP headers, additional information is in
 * the HTTP bodies, in a format set by the SOAP and XML standards, a markup
 * language related to HTML used for web pages. This language is intended to
 * provide the ultimate in self-documentation by providing a universal
 * namespace based on pseudo-URLs called URIs. Note that although a URI looks
 * like a URL (a web address), they are never accessed as such but are used
 * only as identifiers.
 *
 * The POST of a GetDeviceInfo gets information similar to what might be
 * obtained from a probe request or response on Wi-Fi. WPS messages M1-M8
 * are passed via a POST of a PutMessage; the M1-M8 WPS messages are converted
 * to a bin64 ascii representation for encapsulation. When proxying messages,
 * WLANEvent and PutWLANResponse are used.
 *
 * This of course glosses over a lot of details.
 */

#include "includes.h"

#include <time.h>
#include <net/if.h>
#include <netdb.h>
#include <sys/ioctl.h>

#include "common.h"
#include "uuid.h"
#include "base64.h"
#include "wps.h"
#include "wps_i.h"
#include "wps_upnp.h"
#include "wps_upnp_i.h"


/*
 * UPnP allows a client ("control point") to send a server like us ("device")
 * a domain name for registration, and we are supposed to resolve it. This is
 * bad because, using the standard Linux library, we will stall the entire
 * hostapd waiting for resolution.
 *
 * The "correct" solution would be to use an event driven library for domain
 * name resolution such as "ares". However, this would increase code size
 * further. Since it is unlikely that we'll actually see such domain names, we
 * can just refuse to accept them.
 */
#define NO_DOMAIN_NAME_RESOLUTION 1  /* 1 to allow only dotted ip addresses */


/*
 * UPnP does not scale well. If we were in a room with thousands of control
 * points then potentially we could be expected to handle subscriptions for
 * each of them, which would exhaust our memory. So we must set a limit. In
 * practice we are unlikely to see more than one or two.
 */
#define MAX_SUBSCRIPTIONS 4    /* how many subscribing clients we handle */
#define MAX_ADDR_PER_SUBSCRIPTION 8

/* Maximum number of Probe Request events per second */
#define MAX_EVENTS_PER_SEC 5


static struct upnp_wps_device_sm *shared_upnp_device = NULL;


/* Write the current date/time per RFC */
void format_date(struct wpabuf *buf)
{
        const char *weekday_str = "Sun\0Mon\0Tue\0Wed\0Thu\0Fri\0Sat";
        const char *month_str = "Jan\0Feb\0Mar\0Apr\0May\0Jun\0"
                "Jul\0Aug\0Sep\0Oct\0Nov\0Dec";
        struct tm *date;
        time_t t;

        t = time(NULL);
        date = gmtime(&t);
        wpabuf_printf(buf, "%s, %02d %s %d %02d:%02d:%02d GMT",
                      &weekday_str[date->tm_wday * 4], date->tm_mday,
                      &month_str[date->tm_mon * 4], date->tm_year + 1900,
                      date->tm_hour, date->tm_min, date->tm_sec);
}


/***************************************************************************
 * UUIDs (unique identifiers)
 *
 * These are supposed to be unique in all the world.
 * Sometimes permanent ones are used, sometimes temporary ones
 * based on random numbers... there are different rules for valid content
 * of different types.
 * Each uuid is 16 bytes long.
 **************************************************************************/

/* uuid_make -- construct a random UUID
 * The UPnP documents don't seem to offer any guidelines as to which method to
 * use for constructing UUIDs for subscriptions. Presumably any method from
 * rfc4122 is good enough; I've chosen random number method.
 */
static void uuid_make(u8 uuid[UUID_LEN])
{
        os_get_random(uuid, UUID_LEN);

        /* Replace certain bits as specified in rfc4122 or X.667 */
        uuid[6] &= 0x0f; uuid[6] |= (4 << 4);   /* version 4 == random gen */
        uuid[8] &= 0x3f; uuid[8] |= 0x80;
}


/*
 * Subscriber address handling.
 * Since a subscriber may have an arbitrary number of addresses, we have to
 * add a bunch of code to handle them.
 *
 * Addresses are passed in text, and MAY be domain names instead of the (usual
 * and expected) dotted IP addresses. Resolving domain names consumes a lot of
 * resources. Worse, we are currently using the standard Linux getaddrinfo()
 * which will block the entire program until complete or timeout! The proper
 * solution would be to use the "ares" library or similar with more state
 * machine steps etc. or just disable domain name resolution by setting
 * NO_DOMAIN_NAME_RESOLUTION to 1 at top of this file.
 */

/* subscr_addr_delete -- delete single unlinked subscriber address
 * (be sure to unlink first if need be)
 */
void subscr_addr_delete(struct subscr_addr *a)
{
        /*
         * Note: do NOT free domain_and_port or path because they point to
         * memory within the allocation of "a".
         */
        os_free(a);
}


/* subscr_addr_free_all -- unlink and delete list of subscriber addresses. */
static void subscr_addr_free_all(struct subscription *s)
{
        struct subscr_addr *a, *tmp;
        dl_list_for_each_safe(a, tmp, &s->addr_list, struct subscr_addr, list)
        {
                dl_list_del(&a->list);
                subscr_addr_delete(a);
        }
}


/* subscr_addr_add_url -- add address(es) for one url to subscription */
static void subscr_addr_add_url(struct subscription *s, const char *url,
                                size_t url_len)
{
        int alloc_len;
        char *scratch_mem = NULL;
        char *mem;
        char *host;
        char *delim;
        char *path;
        int port = 80;  /* port to send to (default is port 80) */
        struct addrinfo hints;
        struct addrinfo *result = NULL;
        struct addrinfo *rp;
        int rerr;
        size_t host_len, path_len;

        /* url MUST begin with http: */
        if (url_len < 7 || os_strncasecmp(url, "http://", 7))
                goto fail;
        url += 7;
        url_len -= 7;

        /* Make a copy of the string to allow modification during parsing */
        scratch_mem = os_malloc(url_len + 1);
        if (scratch_mem == NULL)
                goto fail;
        os_memcpy(scratch_mem, url, url_len);
        scratch_mem[url_len] = '\0';
        wpa_printf(MSG_DEBUG, "WPS UPnP: Adding URL '%s'", scratch_mem);
        host = scratch_mem;
        path = os_strchr(host, '/');
        if (path)
                *path++ = '\0'; /* null terminate host */

        /* Process and remove optional port component */
        delim = os_strchr(host, ':');
        if (delim) {
                *delim = '\0'; /* null terminate host name for now */
                if (isdigit(delim[1]))
                        port = atol(delim + 1);
        }

        /*
         * getaddrinfo does the right thing with dotted decimal notations, or
         * will resolve domain names. Resolving domain names will unfortunately
         * hang the entire program until it is resolved or it times out
         * internal to getaddrinfo; fortunately we think that the use of actual
         * domain names (vs. dotted decimal notations) should be uncommon.
         */
        os_memset(&hints, 0, sizeof(struct addrinfo));
        hints.ai_family = AF_INET;      /* IPv4 */
        hints.ai_socktype = SOCK_STREAM;
#if NO_DOMAIN_NAME_RESOLUTION
        /* Suppress domain name resolutions that would halt
         * the program for periods of time
         */
        hints.ai_flags = AI_NUMERICHOST;
#else
        /* Allow domain name resolution. */
        hints.ai_flags = 0;
#endif
        hints.ai_protocol = 0;          /* Any protocol? */
        rerr = getaddrinfo(host, NULL /* fill in port ourselves */,
                           &hints, &result);
        if (rerr) {
                wpa_printf(MSG_INFO, "WPS UPnP: Resolve error %d (%s) on: %s",
                           rerr, gai_strerror(rerr), host);
                goto fail;
        }

        if (delim)
                *delim = ':'; /* Restore port */

        host_len = os_strlen(host);
        path_len = path ? os_strlen(path) : 0;
        alloc_len = host_len + 1 + 1 + path_len + 1;

        for (rp = result; rp; rp = rp->ai_next) {
                struct subscr_addr *a;

                /* Limit no. of address to avoid denial of service attack */
                if (dl_list_len(&s->addr_list) >= MAX_ADDR_PER_SUBSCRIPTION) {
                        wpa_printf(MSG_INFO, "WPS UPnP: subscr_addr_add_url: "
                                   "Ignoring excessive addresses");
                        break;
                }

                a = os_zalloc(sizeof(*a) + alloc_len);
                if (a == NULL)
                        break;
                mem = (char *) (a + 1);
                a->domain_and_port = mem;
                os_memcpy(mem, host, host_len);
                mem += host_len + 1;
                a->path = mem;
                if (path == NULL || path[0] != '/')
                        *mem++ = '/';
                if (path)
                        os_memcpy(mem, path, path_len);
                os_memcpy(&a->saddr, rp->ai_addr, sizeof(a->saddr));
                a->saddr.sin_port = htons(port);

                dl_list_add(&s->addr_list, &a->list);
        }

fail:
        if (result)
                freeaddrinfo(result);
        os_free(scratch_mem);
}


/* subscr_addr_list_create -- create list from urls in string.
 *      Each url is enclosed by angle brackets.
 */
static void subscr_addr_list_create(struct subscription *s,
                                    const char *url_list)
{
        const char *end;
        wpa_printf(MSG_DEBUG, "WPS UPnP: Parsing URL list '%s'", url_list);
        for (;;) {
                while (*url_list == ' ' || *url_list == '\t')
                        url_list++;
                if (*url_list != '<')
                        break;
                url_list++;
                end = os_strchr(url_list, '>');
                if (end == NULL)
                        break;
                subscr_addr_add_url(s, url_list, end - url_list);
                url_list = end + 1;
        }
}


int send_wpabuf(int fd, struct wpabuf *buf)
{
        wpa_printf(MSG_DEBUG, "WPS UPnP: Send %lu byte message",
                   (unsigned long) wpabuf_len(buf));
        errno = 0;
        if (write(fd, wpabuf_head(buf), wpabuf_len(buf)) !=
            (int) wpabuf_len(buf)) {
                wpa_printf(MSG_ERROR, "WPS UPnP: Failed to send buffer: "
                           "errno=%d (%s)",
                           errno, strerror(errno));
                return -1;
        }

        return 0;
}


static void wpabuf_put_property(struct wpabuf *buf, const char *name,
                                const char *value)
{
        wpabuf_put_str(buf, "<e:property>");
        wpabuf_printf(buf, "<%s>", name);
        if (value)
                wpabuf_put_str(buf, value);
        wpabuf_printf(buf, "</%s>", name);
        wpabuf_put_str(buf, "</e:property>\n");
}


/**
 * upnp_wps_device_send_event - Queue event messages for subscribers
 * @sm: WPS UPnP state machine from upnp_wps_device_init()
 *
 * This function queues the last WLANEvent to be sent for all currently
 * subscribed UPnP control points. sm->wlanevent must have been set with the
 * encoded data before calling this function.
 */
static void upnp_wps_device_send_event(struct upnp_wps_device_sm *sm)
{
        /* Enqueue event message for all subscribers */
        struct wpabuf *buf; /* holds event message */
        int buf_size = 0;
        struct subscription *s, *tmp;
        /* Actually, utf-8 is the default, but it doesn't hurt to specify it */
        const char *format_head =
                "<?xml version=\"1.0\" encoding=\"utf-8\"?>\n"
                "<e:propertyset xmlns:e=\"urn:schemas-upnp-org:event-1-0\">\n";
        const char *format_tail = "</e:propertyset>\n";
        struct os_time now;

        if (dl_list_empty(&sm->subscriptions)) {
                /* optimize */
                return;
        }

        if (os_get_time(&now) == 0) {
                if (now.sec != sm->last_event_sec) {
                        sm->last_event_sec = now.sec;
                        sm->num_events_in_sec = 1;
                } else {
                        sm->num_events_in_sec++;
                        /*
                         * In theory, this should apply to all WLANEvent
                         * notifications, but EAP messages are of much higher
                         * priority and Probe Request notifications should not
                         * be allowed to drop EAP messages, so only throttle
                         * Probe Request notifications.
                         */
                        if (sm->num_events_in_sec > MAX_EVENTS_PER_SEC &&
                            sm->wlanevent_type ==
                            UPNP_WPS_WLANEVENT_TYPE_PROBE) {
                                wpa_printf(MSG_DEBUG, "WPS UPnP: Throttle "
                                           "event notifications (%u seen "
                                           "during one second)",
                                           sm->num_events_in_sec);
                                return;
                        }
                }
        }

        /* Determine buffer size needed first */
        buf_size += os_strlen(format_head);
        buf_size += 50 + 2 * os_strlen("WLANEvent");
        if (sm->wlanevent)
                buf_size += os_strlen(sm->wlanevent);
        buf_size += os_strlen(format_tail);

        buf = wpabuf_alloc(buf_size);
        if (buf == NULL)
                return;
        wpabuf_put_str(buf, format_head);
        wpabuf_put_property(buf, "WLANEvent", sm->wlanevent);
        wpabuf_put_str(buf, format_tail);

        wpa_printf(MSG_MSGDUMP, "WPS UPnP: WLANEvent message:\n%s",
                   (char *) wpabuf_head(buf));

        dl_list_for_each_safe(s, tmp, &sm->subscriptions, struct subscription,
                              list) {
                event_add(s, buf,
                          sm->wlanevent_type == UPNP_WPS_WLANEVENT_TYPE_PROBE);
        }

        wpabuf_free(buf);
}


/*
 * Event subscription (subscriber machines register with us to receive event
 * messages).
 * This is the result of an incoming HTTP over TCP SUBSCRIBE request.
 */

/* subscription_destroy -- destroy an unlinked subscription
 * Be sure to unlink first if necessary.
 */
void subscription_destroy(struct subscription *s)
{
        struct upnp_wps_device_interface *iface;
        wpa_printf(MSG_DEBUG, "WPS UPnP: Destroy subscription %p", s);
        subscr_addr_free_all(s);
        event_delete_all(s);
        dl_list_for_each(iface, &s->sm->interfaces,
                         struct upnp_wps_device_interface, list)
                upnp_er_remove_notification(iface->wps->registrar, s);
        os_free(s);
}


/* subscription_list_age -- remove expired subscriptions */
static void subscription_list_age(struct upnp_wps_device_sm *sm, time_t now)
{
        struct subscription *s, *tmp;
        dl_list_for_each_safe(s, tmp, &sm->subscriptions,
                              struct subscription, list) {
                if (s->timeout_time > now)
                        break;
                wpa_printf(MSG_DEBUG, "WPS UPnP: Removing aged subscription");
                dl_list_del(&s->list);
                subscription_destroy(s);
        }
}


/* subscription_find -- return existing subscription matching uuid, if any
 * returns NULL if not found
 */
struct subscription * subscription_find(struct upnp_wps_device_sm *sm,
                                        const u8 uuid[UUID_LEN])
{
        struct subscription *s;
        dl_list_for_each(s, &sm->subscriptions, struct subscription, list) {
                if (os_memcmp(s->uuid, uuid, UUID_LEN) == 0)
                        return s; /* Found match */
        }
        return NULL;
}


static struct wpabuf * build_fake_wsc_ack(void)
{
        struct wpabuf *msg = wpabuf_alloc(100);
        if (msg == NULL)
                return NULL;
        wpabuf_put_u8(msg, UPNP_WPS_WLANEVENT_TYPE_EAP);
        wpabuf_put_str(msg, "00:00:00:00:00:00");
        if (wps_build_version(msg) ||
            wps_build_msg_type(msg, WPS_WSC_ACK)) {
                wpabuf_free(msg);
                return NULL;
        }
        /* Enrollee Nonce */
        wpabuf_put_be16(msg, ATTR_ENROLLEE_NONCE);
        wpabuf_put_be16(msg, WPS_NONCE_LEN);
        wpabuf_put(msg, WPS_NONCE_LEN);
        /* Registrar Nonce */
        wpabuf_put_be16(msg, ATTR_REGISTRAR_NONCE);
        wpabuf_put_be16(msg, WPS_NONCE_LEN);
        wpabuf_put(msg, WPS_NONCE_LEN);
        wps_build_wfa_ext(msg, 0, NULL, 0);
        return msg;
}


/* subscription_first_event -- send format/queue event that is automatically
 * sent on a new subscription.
 */
static int subscription_first_event(struct subscription *s)
{
        /*
         * Actually, utf-8 is the default, but it doesn't hurt to specify it.
         *
         * APStatus is apparently a bit set,
         * 0x1 = configuration change (but is always set?)
         * 0x10 = ap is locked
         *
         * Per UPnP spec, we send out the last value of each variable, even
         * for WLANEvent, whatever it was.
         */
        char *wlan_event;
        struct wpabuf *buf;
        int ap_status = 1;      /* TODO: add 0x10 if access point is locked */
        const char *head =
                "<?xml version=\"1.0\" encoding=\"utf-8\"?>\n"
                "<e:propertyset xmlns:e=\"urn:schemas-upnp-org:event-1-0\">\n";
        const char *tail = "</e:propertyset>\n";
        char txt[10];
        int ret;

        if (s->sm->wlanevent == NULL) {
                /*
                 * There has been no events before the subscription. However,
                 * UPnP device architecture specification requires all the
                 * evented variables to be included, so generate a dummy event
                 * for this particular case using a WSC_ACK and all-zeros
                 * nonces. The ER (UPnP control point) will ignore this, but at
                 * least it will learn that WLANEvent variable will be used in
                 * event notifications in the future.
                 */
                struct wpabuf *msg;
                wpa_printf(MSG_DEBUG, "WPS UPnP: Use a fake WSC_ACK as the "
                           "initial WLANEvent");
                msg = build_fake_wsc_ack();
                if (msg) {
                        s->sm->wlanevent = (char *)
                                base64_encode(wpabuf_head(msg),
                                              wpabuf_len(msg), NULL);
                        wpabuf_free(msg);
                }
        }

        wlan_event = s->sm->wlanevent;
        if (wlan_event == NULL || *wlan_event == '\0') {
                wpa_printf(MSG_DEBUG, "WPS UPnP: WLANEvent not known for "
                           "initial event message");
                wlan_event = "";
        }
        buf = wpabuf_alloc(500 + os_strlen(wlan_event));
        if (buf == NULL)
                return -1;

        wpabuf_put_str(buf, head);
        wpabuf_put_property(buf, "STAStatus", "1");
        os_snprintf(txt, sizeof(txt), "%d", ap_status);
        wpabuf_put_property(buf, "APStatus", txt);
        if (*wlan_event)
                wpabuf_put_property(buf, "WLANEvent", wlan_event);
        wpabuf_put_str(buf, tail);

        ret = event_add(s, buf, 0);
        if (ret) {
                wpabuf_free(buf);
                return ret;
        }
        wpabuf_free(buf);

        return 0;
}


/**
 * subscription_start - Remember a UPnP control point to send events to.
 * @sm: WPS UPnP state machine from upnp_wps_device_init()
 * @callback_urls: Callback URLs
 * Returns: %NULL on error, or pointer to new subscription structure.
 */
struct subscription * subscription_start(struct upnp_wps_device_sm *sm,
                                         const char *callback_urls)
{
        struct subscription *s;
        time_t now = time(NULL);
        time_t expire = now + UPNP_SUBSCRIBE_SEC;

        /* Get rid of expired subscriptions so we have room */
        subscription_list_age(sm, now);

        /* If too many subscriptions, remove oldest */
        if (dl_list_len(&sm->subscriptions) >= MAX_SUBSCRIPTIONS) {
                s = dl_list_first(&sm->subscriptions, struct subscription,
                                  list);
                wpa_printf(MSG_INFO, "WPS UPnP: Too many subscriptions, "
                           "trashing oldest");
                dl_list_del(&s->list);
                subscription_destroy(s);
        }

        s = os_zalloc(sizeof(*s));
        if (s == NULL)
                return NULL;
        dl_list_init(&s->addr_list);
        dl_list_init(&s->event_queue);

        s->sm = sm;
        s->timeout_time = expire;
        uuid_make(s->uuid);
        subscr_addr_list_create(s, callback_urls);
        if (dl_list_empty(&s->addr_list)) {
                wpa_printf(MSG_DEBUG, "WPS UPnP: No valid callback URLs in "
                           "'%s' - drop subscription", callback_urls);
                subscription_destroy(s);
                return NULL;
        }

        /* Add to end of list, since it has the highest expiration time */
        dl_list_add_tail(&sm->subscriptions, &s->list);
        /* Queue up immediate event message (our last event)
         * as required by UPnP spec.
         */
        if (subscription_first_event(s)) {
                wpa_printf(MSG_INFO, "WPS UPnP: Dropping subscriber due to "
                           "event backlog");
                dl_list_del(&s->list);
                subscription_destroy(s);
                return NULL;
        }
        wpa_printf(MSG_DEBUG, "WPS UPnP: Subscription %p started with %s",
                   s, callback_urls);
        /* Schedule sending this */
        event_send_all_later(sm);
        return s;
}


/* subscription_renew -- find subscription and reset timeout */
struct subscription * subscription_renew(struct upnp_wps_device_sm *sm,
                                         const u8 uuid[UUID_LEN])
{
        time_t now = time(NULL);
        time_t expire = now + UPNP_SUBSCRIBE_SEC;
        struct subscription *s = subscription_find(sm, uuid);
        if (s == NULL)
                return NULL;
        wpa_printf(MSG_DEBUG, "WPS UPnP: Subscription renewed");
        dl_list_del(&s->list);
        s->timeout_time = expire;
        /* add back to end of list, since it now has highest expiry */
        dl_list_add_tail(&sm->subscriptions, &s->list);
        return s;
}


/**
 * upnp_wps_device_send_wlan_event - Event notification
 * @sm: WPS UPnP state machine from upnp_wps_device_init()
 * @from_mac_addr: Source (Enrollee) MAC address for the event
 * @ev_type: Event type
 * @msg: Event data
 * Returns: 0 on success, -1 on failure
 *
 * Tell external Registrars (UPnP control points) that something happened. In
 * particular, events include WPS messages from clients that are proxied to
 * external Registrars.
 */
int upnp_wps_device_send_wlan_event(struct upnp_wps_device_sm *sm,
                                    const u8 from_mac_addr[ETH_ALEN],
                                    enum upnp_wps_wlanevent_type ev_type,
                                    const struct wpabuf *msg)
{
        int ret = -1;
        char type[2];
        const u8 *mac = from_mac_addr;
        char mac_text[18];
        u8 *raw = NULL;
        size_t raw_len;
        char *val;
        size_t val_len;
        int pos = 0;

        if (!sm)
                goto fail;

        os_snprintf(type, sizeof(type), "%1u", ev_type);

        raw_len = 1 + 17 + (msg ? wpabuf_len(msg) : 0);
        raw = os_zalloc(raw_len);
        if (!raw)
                goto fail;

        *(raw + pos) = (u8) ev_type;
        pos += 1;
        os_snprintf(mac_text, sizeof(mac_text), MACSTR, MAC2STR(mac));
        wpa_printf(MSG_DEBUG, "WPS UPnP: Proxying WLANEvent from %s",
                   mac_text);
        os_memcpy(raw + pos, mac_text, 17);
        pos += 17;
        if (msg) {
                os_memcpy(raw + pos, wpabuf_head(msg), wpabuf_len(msg));
                pos += wpabuf_len(msg);
        }
        raw_len = pos;

        val = (char *) base64_encode(raw, raw_len, &val_len);
        if (val == NULL)
                goto fail;

        os_free(sm->wlanevent);
        sm->wlanevent = val;
        sm->wlanevent_type = ev_type;
        upnp_wps_device_send_event(sm);

        ret = 0;

fail:
        os_free(raw);

        return ret;
}


#if defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
#include <sys/sysctl.h>
#include <net/route.h>
#include <net/if_dl.h>

static int eth_get(const char *device, u8 ea[ETH_ALEN])
{
        struct if_msghdr *ifm;
        struct sockaddr_dl *sdl;
        u_char *p, *buf;
        size_t len;
        int mib[] = { CTL_NET, AF_ROUTE, 0, AF_LINK, NET_RT_IFLIST, 0 };

        if (sysctl(mib, 6, NULL, &len, NULL, 0) < 0)
                return -1;
        if ((buf = os_malloc(len)) == NULL)
                return -1;
        if (sysctl(mib, 6, buf, &len, NULL, 0) < 0) {
                os_free(buf);
                return -1;
        }
        for (p = buf; p < buf + len; p += ifm->ifm_msglen) {
                ifm = (struct if_msghdr *)p;
                sdl = (struct sockaddr_dl *)(ifm + 1);
                if (ifm->ifm_type != RTM_IFINFO ||
                    (ifm->ifm_addrs & RTA_IFP) == 0)
                        continue;
                if (sdl->sdl_family != AF_LINK || sdl->sdl_nlen == 0 ||
                    os_memcmp(sdl->sdl_data, device, sdl->sdl_nlen) != 0)
                        continue;
                os_memcpy(ea, LLADDR(sdl), sdl->sdl_alen);
                break;
        }
        os_free(buf);

        if (p >= buf + len) {
                errno = ESRCH;
                return -1;
        }
        return 0;
}
#endif /* __FreeBSD__ */


/**
 * get_netif_info - Get hw and IP addresses for network device
 * @net_if: Selected network interface name
 * @ip_addr: Buffer for returning IP address in network byte order
 * @ip_addr_text: Buffer for returning a pointer to allocated IP address text
 * @mac: Buffer for returning MAC address
 * Returns: 0 on success, -1 on failure
 */
int get_netif_info(const char *net_if, unsigned *ip_addr, char **ip_addr_text,
                   u8 mac[ETH_ALEN])
{
        struct ifreq req;
        int sock = -1;
        struct sockaddr_in *addr;
        struct in_addr in_addr;

        *ip_addr_text = os_zalloc(16);
        if (*ip_addr_text == NULL)
                goto fail;

        sock = socket(AF_INET, SOCK_DGRAM, 0);
        if (sock < 0)
                goto fail;

        os_strlcpy(req.ifr_name, net_if, sizeof(req.ifr_name));
        if (ioctl(sock, SIOCGIFADDR, &req) < 0) {
                wpa_printf(MSG_ERROR, "WPS UPnP: SIOCGIFADDR failed: %d (%s)",
                           errno, strerror(errno));
                goto fail;
        }
        addr = (void *) &req.ifr_addr;
        *ip_addr = addr->sin_addr.s_addr;
        in_addr.s_addr = *ip_addr;
        os_snprintf(*ip_addr_text, 16, "%s", inet_ntoa(in_addr));

#ifdef __linux__
        os_strlcpy(req.ifr_name, net_if, sizeof(req.ifr_name));
        if (ioctl(sock, SIOCGIFHWADDR, &req) < 0) {
                wpa_printf(MSG_ERROR, "WPS UPnP: SIOCGIFHWADDR failed: "
                           "%d (%s)", errno, strerror(errno));
                goto fail;
        }
        os_memcpy(mac, req.ifr_addr.sa_data, 6);
#elif defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
        if (eth_get(net_if, mac) < 0) {
                wpa_printf(MSG_ERROR, "WPS UPnP: Failed to get MAC address");
                goto fail;
        }
#else
#error MAC address fetch not implemented
#endif

        close(sock);
        return 0;

fail:
        if (sock >= 0)
                close(sock);
        os_free(*ip_addr_text);
        *ip_addr_text = NULL;
        return -1;
}


static void upnp_wps_free_msearchreply(struct dl_list *head)
{
        struct advertisement_state_machine *a, *tmp;
        dl_list_for_each_safe(a, tmp, head, struct advertisement_state_machine,
                              list)
                msearchreply_state_machine_stop(a);
}


static void upnp_wps_free_subscriptions(struct dl_list *head,
                                        struct wps_registrar *reg)
{
        struct subscription *s, *tmp;
        dl_list_for_each_safe(s, tmp, head, struct subscription, list) {
                if (reg && s->reg != reg)
                        continue;
                dl_list_del(&s->list);
                subscription_destroy(s);
        }
}


/**
 * upnp_wps_device_stop - Stop WPS UPnP operations on an interface
 * @sm: WPS UPnP state machine from upnp_wps_device_init()
 */
static void upnp_wps_device_stop(struct upnp_wps_device_sm *sm)
{
        if (!sm || !sm->started)
                return;

        wpa_printf(MSG_DEBUG, "WPS UPnP: Stop device");
        web_listener_stop(sm);
        upnp_wps_free_msearchreply(&sm->msearch_replies);
        upnp_wps_free_subscriptions(&sm->subscriptions, NULL);

        advertisement_state_machine_stop(sm, 1);

        event_send_stop_all(sm);
        os_free(sm->wlanevent);
        sm->wlanevent = NULL;
        os_free(sm->ip_addr_text);
        sm->ip_addr_text = NULL;
        if (sm->multicast_sd >= 0)
                close(sm->multicast_sd);
        sm->multicast_sd = -1;
        ssdp_listener_stop(sm);

        sm->started = 0;
}


/**
 * upnp_wps_device_start - Start WPS UPnP operations on an interface
 * @sm: WPS UPnP state machine from upnp_wps_device_init()
 * @net_if: Selected network interface name
 * Returns: 0 on success, -1 on failure
 */
static int upnp_wps_device_start(struct upnp_wps_device_sm *sm, char *net_if)
{
        if (!sm || !net_if)
                return -1;

        if (sm->started)
                upnp_wps_device_stop(sm);

        sm->multicast_sd = -1;
        sm->ssdp_sd = -1;
        sm->started = 1;
        sm->advertise_count = 0;

        /* Fix up linux multicast handling */
        if (add_ssdp_network(net_if))
                goto fail;

        /* Determine which IP and mac address we're using */
        if (get_netif_info(net_if, &sm->ip_addr, &sm->ip_addr_text,
                           sm->mac_addr)) {
                wpa_printf(MSG_INFO, "WPS UPnP: Could not get IP/MAC address "
                           "for %s. Does it have IP address?", net_if);
                goto fail;
        }

        /* Listen for incoming TCP connections so that others
         * can fetch our "xml files" from us.
         */
        if (web_listener_start(sm))
                goto fail;

        /* Set up for receiving discovery (UDP) packets */
        if (ssdp_listener_start(sm))
                goto fail;

        /* Set up for sending multicast */
        if (ssdp_open_multicast(sm) < 0)
                goto fail;

        /*
         * Broadcast NOTIFY messages to let the world know we exist.
         * This is done via a state machine since the messages should not be
         * all sent out at once.
         */
        if (advertisement_state_machine_start(sm))
                goto fail;

        return 0;

fail:
        upnp_wps_device_stop(sm);
        return -1;
}


static struct upnp_wps_device_interface *
upnp_wps_get_iface(struct upnp_wps_device_sm *sm, void *priv)
{
        struct upnp_wps_device_interface *iface;
        dl_list_for_each(iface, &sm->interfaces,
                         struct upnp_wps_device_interface, list) {
                if (iface->priv == priv)
                        return iface;
        }
        return NULL;
}


/**
 * upnp_wps_device_deinit - Deinitialize WPS UPnP
 * @sm: WPS UPnP state machine from upnp_wps_device_init()
 * @priv: External context data that was used in upnp_wps_device_init() call
 */
void upnp_wps_device_deinit(struct upnp_wps_device_sm *sm, void *priv)
{
        struct upnp_wps_device_interface *iface;

        if (!sm)
                return;

        iface = upnp_wps_get_iface(sm, priv);
        if (iface == NULL) {
                wpa_printf(MSG_ERROR, "WPS UPnP: Could not find the interface "
                           "instance to deinit");
                return;
        }
        wpa_printf(MSG_DEBUG, "WPS UPnP: Deinit interface instance %p", iface);
        if (dl_list_len(&sm->interfaces) == 1) {
                wpa_printf(MSG_DEBUG, "WPS UPnP: Deinitializing last instance "
                           "- free global device instance");
                upnp_wps_device_stop(sm);
        } else
                upnp_wps_free_subscriptions(&sm->subscriptions,
                                            iface->wps->registrar);
        dl_list_del(&iface->list);

        if (iface->peer.wps)
                wps_deinit(iface->peer.wps);
        os_free(iface->ctx->ap_pin);
        os_free(iface->ctx);
        os_free(iface);

        if (dl_list_empty(&sm->interfaces)) {
                os_free(sm->root_dir);
                os_free(sm->desc_url);
                os_free(sm);
                shared_upnp_device = NULL;
        }
}


/**
 * upnp_wps_device_init - Initialize WPS UPnP
 * @ctx: callback table; we must eventually free it
 * @wps: Pointer to longterm WPS context
 * @priv: External context data that will be used in callbacks
 * @net_if: Selected network interface name
 * Returns: WPS UPnP state or %NULL on failure
 */
struct upnp_wps_device_sm *
upnp_wps_device_init(struct upnp_wps_device_ctx *ctx, struct wps_context *wps,
                     void *priv, char *net_if)
{
        struct upnp_wps_device_sm *sm;
        struct upnp_wps_device_interface *iface;
        int start = 0;

        iface = os_zalloc(sizeof(*iface));
        if (iface == NULL) {
                os_free(ctx->ap_pin);
                os_free(ctx);
                return NULL;
        }
        wpa_printf(MSG_DEBUG, "WPS UPnP: Init interface instance %p", iface);

        iface->ctx = ctx;
        iface->wps = wps;
        iface->priv = priv;

        if (shared_upnp_device) {
                wpa_printf(MSG_DEBUG, "WPS UPnP: Share existing device "
                           "context");
                sm = shared_upnp_device;
        } else {
                wpa_printf(MSG_DEBUG, "WPS UPnP: Initialize device context");
                sm = os_zalloc(sizeof(*sm));
                if (!sm) {
                        wpa_printf(MSG_ERROR, "WPS UPnP: upnp_wps_device_init "
                                   "failed");
                        os_free(iface);
                        os_free(ctx->ap_pin);
                        os_free(ctx);
                        return NULL;
                }
                shared_upnp_device = sm;

                dl_list_init(&sm->msearch_replies);
                dl_list_init(&sm->subscriptions);
                dl_list_init(&sm->interfaces);
                start = 1;
        }

        dl_list_add(&sm->interfaces, &iface->list);

        if (start && upnp_wps_device_start(sm, net_if)) {
                upnp_wps_device_deinit(sm, priv);
                return NULL;
        }


        return sm;
}


/**
 * upnp_wps_subscribers - Check whether there are any event subscribers
 * @sm: WPS UPnP state machine from upnp_wps_device_init()
 * Returns: 0 if no subscribers, 1 if subscribers
 */
int upnp_wps_subscribers(struct upnp_wps_device_sm *sm)
{
        return !dl_list_empty(&sm->subscriptions);
}


int upnp_wps_set_ap_pin(struct upnp_wps_device_sm *sm, const char *ap_pin)
{
        struct upnp_wps_device_interface *iface;
        if (sm == NULL)
                return 0;

        dl_list_for_each(iface, &sm->interfaces,
                         struct upnp_wps_device_interface, list) {
                os_free(iface->ctx->ap_pin);
                if (ap_pin) {
                        iface->ctx->ap_pin = os_strdup(ap_pin);
                        if (iface->ctx->ap_pin == NULL)
                                return -1;
                } else
                        iface->ctx->ap_pin = NULL;
        }

        return 0;
}