wps_upnp_event.c

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#include "includes.h"
#include <assert.h>

#include "common.h"
#include "eloop.h"
#include "uuid.h"
#include "http_client.h"
#include "wps_defs.h"
#include "wps_upnp.h"
#include "wps_upnp_i.h"

/*
 * Event message generation (to subscribers)
 *
 * We make a separate copy for each message for each subscriber. This memory
 * wasted could be limited (adding code complexity) by sharing copies, keeping
 * a usage count and freeing when zero.
 *
 * Sending a message requires using a HTTP over TCP NOTIFY
 * (like a PUT) which requires a number of states..
 */

#define MAX_EVENTS_QUEUED 20   /* How far behind queued events */
#define EVENT_TIMEOUT_SEC 30   /* Drop sending event after timeout */

/* How long to wait before sending event */
#define EVENT_DELAY_SECONDS 0
#define EVENT_DELAY_MSEC 0

/*
 * Event information that we send to each subscriber is remembered in this
 * struct. The event cannot be sent by simple UDP; it has to be sent by a HTTP
 * over TCP transaction which requires various states.. It may also need to be
 * retried at a different address (if more than one is available).
 *
 * TODO: As an optimization we could share data between subscribers.
 */
struct wps_event_ {
        struct wps_event_ *next;
        struct wps_event_ *prev;        /* double linked list */
        struct subscription *s;         /* parent */
        unsigned subscriber_sequence;   /* which event for this subscription*/
        int retry;                      /* which retry */
        struct subscr_addr *addr;       /* address to connect to */
        struct wpabuf *data;            /* event data to send */
        struct http_client *http_event;
};


/* event_clean -- clean sockets etc. of event
 * Leaves data, retry count etc. alone.
 */
static void event_clean(struct wps_event_ *e)
{
        if (e->s->current_event == e)
                e->s->current_event = NULL;
        http_client_free(e->http_event);
        e->http_event = NULL;
}


/* event_delete -- delete single unqueued event
 * (be sure to dequeue first if need be)
 */
static void event_delete(struct wps_event_ *e)
{
        event_clean(e);
        wpabuf_free(e->data);
        os_free(e);
}


/* event_dequeue -- get next event from the queue
 * Returns NULL if empty.
 */
static struct wps_event_ *event_dequeue(struct subscription *s)
{
        struct wps_event_ **event_head = &s->event_queue;
        struct wps_event_ *e = *event_head;
        if (e == NULL)
                return NULL;
        e->next->prev = e->prev;
        e->prev->next = e->next;
        if (*event_head == e) {
                if (e == e->next) {
                        /* last in queue */
                        *event_head = NULL;
                } else {
                        *event_head = e->next;
                }
        }
        s->n_queue--;
        e->next = e->prev = NULL;
        /* but parent "s" is still valid */
        return e;
}


/* event_enqueue_at_end -- add event to end of queue */
static void event_enqueue_at_end(struct subscription *s, struct wps_event_ *e)
{
        struct wps_event_ **event_head = &s->event_queue;
        if (*event_head == NULL) {
                *event_head = e->next = e->prev = e;
        } else {
                e->next = *event_head;
                e->prev = e->next->prev;
                e->prev->next = e;
                e->next->prev = e;
        }
        s->n_queue++;
}


/* event_enqueue_at_begin -- add event to begin of queue
 * (appropriate for retrying event only)
 */
static void event_enqueue_at_begin(struct subscription *s,
                                   struct wps_event_ *e)
{
        struct wps_event_ **event_head = &s->event_queue;
        if (*event_head == NULL) {
                *event_head = e->next = e->prev = e;
        } else {
                e->prev = *event_head;
                e->next = e->prev->next;
                e->prev->next = e;
                e->next->prev = e;
                *event_head = e;
        }
        s->n_queue++;
}


/* event_delete_all -- delete entire event queue and current event */
void event_delete_all(struct subscription *s)
{
        struct wps_event_ *e;
        while ((e = event_dequeue(s)) != NULL)
                event_delete(e);
        if (s->current_event) {
                event_delete(s->current_event);
                /* will set: s->current_event = NULL;  */
        }
}


static void event_retry(struct wps_event_ *e, int do_next_address)
{
        struct subscription *s = e->s;
        struct upnp_wps_device_sm *sm = s->sm;

        event_clean(e);
        /* will set: s->current_event = NULL; */

        if (do_next_address)
                e->retry++;
        if (e->retry >= s->n_addr) {
                wpa_printf(MSG_DEBUG, "WPS UPnP: Giving up on sending event "
                           "for %s", e->addr->domain_and_port);
                return;
        }
        event_enqueue_at_begin(s, e);
        event_send_all_later(sm);
}


static struct wpabuf * event_build_message(struct wps_event_ *e)
{
        struct wpabuf *buf;
        char *b;

        buf = wpabuf_alloc(1000 + wpabuf_len(e->data));
        if (buf == NULL)
                return NULL;
        wpabuf_printf(buf, "NOTIFY %s HTTP/1.1\r\n", e->addr->path);
        wpabuf_put_str(buf, "SERVER: Unspecified, UPnP/1.0, Unspecified\r\n");
        wpabuf_printf(buf, "HOST: %s\r\n", e->addr->domain_and_port);
        wpabuf_put_str(buf, "CONTENT-TYPE: text/xml; charset=\"utf-8\"\r\n"
                       "NT: upnp:event\r\n"
                       "NTS: upnp:propchange\r\n");
        wpabuf_put_str(buf, "SID: uuid:");
        b = wpabuf_put(buf, 0);
        uuid_bin2str(e->s->uuid, b, 80);
        wpabuf_put(buf, os_strlen(b));
        wpabuf_put_str(buf, "\r\n");
        wpabuf_printf(buf, "SEQ: %u\r\n", e->subscriber_sequence);
        wpabuf_printf(buf, "CONTENT-LENGTH: %d\r\n",
                      (int) wpabuf_len(e->data));
        wpabuf_put_str(buf, "\r\n"); /* terminating empty line */
        wpabuf_put_buf(buf, e->data);
        return buf;
}


static void event_http_cb(void *ctx, struct http_client *c,
                          enum http_client_event event)
{
        struct wps_event_ *e = ctx;
        struct subscription *s = e->s;

        switch (event) {
        case HTTP_CLIENT_OK:
                wpa_printf(MSG_DEBUG,
                           "WPS UPnP: Got event reply OK from "
                           "%s", e->addr->domain_and_port);
                event_delete(e);

                /* Schedule sending more if there is more to send */
                if (s->event_queue)
                        event_send_all_later(s->sm);
                break;
        case HTTP_CLIENT_FAILED:
        case HTTP_CLIENT_INVALID_REPLY:
                wpa_printf(MSG_DEBUG, "WPS UPnP: Failed to send event to %s",
                           e->addr->domain_and_port);

                /*
                 * If other side doesn't like what we say, forget about them.
                 * (There is no way to tell other side that we are dropping
                 * them...).
                 * Alternately, we could just do event_delete(e)
                 */
                wpa_printf(MSG_DEBUG, "WPS UPnP: Deleting subscription due to "
                           "errors");
                subscription_unlink(s);
                subscription_destroy(s);
                break;
        case HTTP_CLIENT_TIMEOUT:
                wpa_printf(MSG_DEBUG, "WPS UPnP: Event send timeout");
                event_retry(e, 1);
        }
}


/* event_send_start -- prepare to send a event message to subscriber
 *
 * This gets complicated because:
 * -- The message is sent via TCP and we have to keep the stream open
 *      for 30 seconds to get a response... then close it.
 * -- But we might have other event happen in the meantime...
 *      we have to queue them, if we lose them then the subscriber will
 *      be forced to unsubscribe and subscribe again.
 * -- If multiple URLs are provided then we are supposed to try successive
 *      ones after 30 second timeout.
 * -- The URLs might use domain names instead of dotted decimal addresses,
 *      and resolution of those may cause unwanted sleeping.
 * -- Doing the initial TCP connect can take a while, so we have to come
 *      back after connection and then send the data.
 *
 * Returns nonzero on error;
 *
 * Prerequisite: No current event send (s->current_event == NULL)
 *      and non-empty queue.
 */
static int event_send_start(struct subscription *s)
{
        struct wps_event_ *e;
        int itry;
        struct wpabuf *buf;

        /*
         * Assume we are called ONLY with no current event and ONLY with
         * nonempty event queue and ONLY with at least one address to send to.
         */
        assert(s->addr_list != NULL);
        assert(s->current_event == NULL);
        assert(s->event_queue != NULL);

        s->current_event = e = event_dequeue(s);

        /* Use address acc. to no. of retries */
        e->addr = s->addr_list;
        for (itry = 0; itry < e->retry; itry++)
                e->addr = e->addr->next;

        buf = event_build_message(e);
        if (buf == NULL) {
                event_retry(e, 0);
                return -1;
        }

        e->http_event = http_client_addr(&e->addr->saddr, buf, 0,
                                         event_http_cb, e);
        if (e->http_event == NULL) {
                wpabuf_free(buf);
                event_retry(e, 0);
                return -1;
        }

        return 0;
}


/* event_send_all_later_handler -- actually send events as needed */
static void event_send_all_later_handler(void *eloop_data, void *user_ctx)
{
        struct upnp_wps_device_sm *sm = user_ctx;
        struct subscription *s;
        struct subscription *s_old;
        int nerrors = 0;

        sm->event_send_all_queued = 0;
        s = sm->subscriptions;
        if (s == NULL)
                return;
        do {
                if (s->addr_list == NULL) {
                        /* if we've given up on all addresses */
                        wpa_printf(MSG_DEBUG, "WPS UPnP: Removing "
                                   "subscription with no addresses");
                        s_old = s;
                        s = s_old->next;
                        subscription_unlink(s_old);
                        subscription_destroy(s_old);
                } else {
                        if (s->current_event == NULL /* not busy */ &&
                            s->event_queue != NULL /* more to do */) {
                                if (event_send_start(s))
                                        nerrors++;
                        }
                        s = s->next;
                }
        } while (sm->subscriptions != NULL && s != sm->subscriptions);

        if (nerrors) {
                /* Try again later */
                event_send_all_later(sm);
        }
}


/* event_send_all_later -- schedule sending events to all subscribers
 * that need it.
 * This avoids two problems:
 * -- After getting a subscription, we should not send the first event
 *      until after our reply is fully queued to be sent back,
 * -- Possible stack depth or infinite recursion issues.
 */
void event_send_all_later(struct upnp_wps_device_sm *sm)
{
        /*
         * The exact time in the future isn't too important. Waiting a bit
         * might let us do several together.
         */
        if (sm->event_send_all_queued)
                return;
        sm->event_send_all_queued = 1;
        eloop_register_timeout(EVENT_DELAY_SECONDS, EVENT_DELAY_MSEC,
                               event_send_all_later_handler, NULL, sm);
}


/* event_send_stop_all -- cleanup */
void event_send_stop_all(struct upnp_wps_device_sm *sm)
{
        if (sm->event_send_all_queued)
                eloop_cancel_timeout(event_send_all_later_handler, NULL, sm);
        sm->event_send_all_queued = 0;
}


int event_add(struct subscription *s, const struct wpabuf *data)
{
        struct wps_event_ *e;

        if (s->n_queue >= MAX_EVENTS_QUEUED) {
                wpa_printf(MSG_DEBUG, "WPS UPnP: Too many events queued for "
                           "subscriber");
                return 1;
        }

        e = os_zalloc(sizeof(*e));
        if (e == NULL)
                return 1;
        e->s = s;
        e->data = wpabuf_dup(data);
        if (e->data == NULL) {
                os_free(e);
                return 1;
        }
        e->subscriber_sequence = s->next_subscriber_sequence++;
        if (s->next_subscriber_sequence == 0)
                s->next_subscriber_sequence++;
        event_enqueue_at_end(s, e);
        event_send_all_later(s->sm);
        return 0;
}