res_calendar_exchange.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2008 - 2009, Digium, Inc.
 *
 * Terry Wilson <twilson@digium.com>
 *
 * See http://www.asterisk.org for more information about
 * the Asterisk project. Please do not directly contact
 * any of the maintainers of this project for assistance;
 * the project provides a web site, mailing lists and IRC
 * channels for your use.
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License Version 2. See the LICENSE file
 * at the top of the source tree.
 */
 
/*! \file
 * \brief Resource for handling MS Exchange calendars
 */
 
/*** MODULEINFO
    <depend>res_calendar</depend>
    <depend>neon</depend>
    <depend>ical</depend>
    <depend>iksemel</depend>
    <support_level>extended</support_level>
***/
 
#include "asterisk.h"
 
#include <libical/ical.h>
#include <ne_session.h>
#include <ne_uri.h>
#include <ne_request.h>
#include <ne_auth.h>
#include <ne_redirect.h>
#include <iksemel.h>
 
#include "asterisk/module.h"
#include "asterisk/channel.h"
#include "asterisk/calendar.h"
#include "asterisk/lock.h"
#include "asterisk/config.h"
#include "asterisk/astobj2.h"
#include "asterisk/uuid.h"
 
static void *exchangecal_load_calendar(void *data);
static void *unref_exchangecal(void *obj);
static int exchangecal_write_event(struct ast_calendar_event *event);
 
static struct ast_calendar_tech exchangecal_tech = {
    .type = "exchange",
    .description = "MS Exchange calendars",
    .module = AST_MODULE,
    .load_calendar = exchangecal_load_calendar,
    .unref_calendar = unref_exchangecal,
    .write_event = exchangecal_write_event,
};
 
struct exchangecal_pvt {
    AST_DECLARE_STRING_FIELDS(
        AST_STRING_FIELD(url);
        AST_STRING_FIELD(user);
        AST_STRING_FIELD(secret);
    );
    struct ast_calendar *owner;
    ne_uri uri;
    ne_session *session;
    struct ao2_container *events;
};
 
struct xmlstate {
    char tag[80];
    int in_response;
    int in_propstat;
    int in_prop;
    void *ptr;
    struct exchangecal_pvt *pvt;
};
 
static int parse_tag(void *data, char *name, char **atts, int type)
{
    struct xmlstate *state = data;
    char *tmp;
 
    if ((tmp = strchr(name, ':'))) {
        tmp++;
    } else {
        return IKS_HOOK;
    }
 
    ast_copy_string(state->tag, tmp, sizeof(state->tag));
 
    switch (type) {
    case IKS_OPEN:
        if (!strcasecmp(state->tag, "response")) {
            struct ast_calendar_event *event;
 
            state->in_response = 1;
            if (!(event = ast_calendar_event_alloc(state->pvt->owner))) {
                return IKS_NOMEM;
            }
            state->ptr = event;
        } else if (!strcasecmp(state->tag, "propstat")) {
            state->in_propstat = 1;
        } else if (!strcasecmp(state->tag, "prop")) {
            state->in_prop = 1;
        }
        break;
 
    case IKS_CLOSE:
        if (!strcasecmp(state->tag, "response")) {
            struct ao2_container *events = state->pvt->events;
            struct ast_calendar_event *event = state->ptr;
 
            state->in_response = 0;
            if (ast_strlen_zero(event->uid)) {
                ast_log(LOG_ERROR, "This event has no UID, something has gone wrong\n");
                event = ast_calendar_unref_event(event);
                return IKS_HOOK;
            }
            ao2_link(events, event);
            event = ast_calendar_unref_event(event);
        } else if (!strcasecmp(state->tag, "propstat")) {
            state->in_propstat = 0;
        } else if (!strcasecmp(state->tag, "prop")) {
            state->in_prop = 0;
        }
        break;
 
    default:
        return IKS_OK;
    }
 
    return IKS_OK;
}
 
static time_t mstime_to_time_t(char *mstime)
{
    char *read, *write;
    icaltimetype tt;
    for (read = write = mstime; *read; read++) {
        if (*read == '.') {
            *write++ = 'Z';
            *write = '\0';
            break;
        }
        if (*read == '-' || *read == ':')
            continue;
        *write = *read;
        write++;
    }
 
    tt = icaltime_from_string(mstime);
    return icaltime_as_timet(tt);
}
 
static enum ast_calendar_busy_state msbusy_to_bs(const char *msbusy)
{
    if (!strcasecmp(msbusy, "FREE")) {
        return AST_CALENDAR_BS_FREE;
    } else if (!strcasecmp(msbusy, "TENTATIVE")) {
        return AST_CALENDAR_BS_BUSY_TENTATIVE;
    } else {
        return AST_CALENDAR_BS_BUSY;
    }
}
 
static int parse_cdata(void *data, char *value, size_t len)
{
    char *str;
    struct xmlstate *state = data;
    struct ast_calendar_event *event = state->ptr;
 
 
    str = ast_skip_blanks(value);
 
    if (str == value + len)
        return IKS_OK;
 
    if (!(str = ast_calloc(1, len + 1))) {
        return IKS_NOMEM;
    }
    memcpy(str, value, len);
    if (!(state->in_response && state->in_propstat && state->in_prop)) {
        ast_free(str);
        return IKS_OK;
    }
    /* We use ast_string_field_build here because libiksemel is parsing CDATA with &lt; as
     * new elements which is a bit odd and shouldn't happen */
    if (!strcasecmp(state->tag, "subject")) {
        ast_string_field_build(event, summary, "%s%s", event->summary, str);
    } else if (!strcasecmp(state->tag, "location")) {
        ast_string_field_build(event, location, "%s%s", event->location, str);
    } else if (!strcasecmp(state->tag, "uid")) {
        ast_string_field_build(event, uid, "%s%s", event->location, str);
    } else if (!strcasecmp(state->tag, "organizer")) {
        ast_string_field_build(event, organizer, "%s%s", event->organizer, str);
    } else if (!strcasecmp(state->tag, "textdescription")) {
        ast_string_field_build(event, description, "%s%s", event->description, str);
    } else if (!strcasecmp(state->tag, "dtstart")) {
        event->start = mstime_to_time_t(str);
    } else if (!strcasecmp(state->tag, "dtend")) {
        event->end = mstime_to_time_t(str);
    } else if (!strcasecmp(state->tag, "busystatus")) {
        event->busy_state = msbusy_to_bs(str);
    } else if (!strcasecmp(state->tag, "reminderoffset")) {
        /*XXX Currently we rely on event->start being set first which means we rely on the response order
         * which technically should be fine since the query returns in the order we ask for, but ... */
        event->alarm = event->start - atoi(str);
    }
 
    ast_free(str);
    return IKS_OK;
}
 
static void exchangecal_destructor(void *obj)
{
    struct exchangecal_pvt *pvt = obj;
 
    ast_debug(1, "Destroying pvt for Exchange calendar %s\n", pvt->owner->name);
    if (pvt->session) {
        ne_session_destroy(pvt->session);
    }
    ne_uri_free(&pvt->uri);
    ast_string_field_free_memory(pvt);
 
    ao2_callback(pvt->events, OBJ_UNLINK | OBJ_NODATA | OBJ_MULTIPLE, NULL, NULL);
 
    ao2_ref(pvt->events, -1);
}
 
static void *unref_exchangecal(void *obj)
{
    struct exchangecal_pvt *pvt = obj;
 
    ao2_ref(pvt, -1);
    return NULL;
}
 
/* It is very important to use the return value of this function as a realloc could occur */
static struct ast_str *generate_exchange_uuid(struct ast_str *uid)
{
    char buffer[AST_UUID_STR_LEN];
 
    ast_uuid_generate_str(buffer, sizeof(buffer));
    ast_str_set(&uid, 0, "%s", buffer);
    return uid;
}
 
static int is_valid_uuid(struct ast_str *uid)
{
    struct ast_uuid *uuid = ast_str_to_uuid(ast_str_buffer(uid));
 
    if (uuid) {
        ast_free(uuid);
        return 1;
    }
 
    return 0;
}
 
static struct ast_str *xml_encode_str(struct ast_str *dst, const char *src)
{
    const char *tmp;
    char buf[7];
 
    for (tmp = src; *tmp; tmp++) {
        switch (*tmp) {
        case '\"':
            strcpy(buf, "&quot;");
            break;
 
        case '\'':
            strcpy(buf, "&apos;");
            break;
 
        case '&':
            strcpy(buf, "&amp;");
            break;
 
        case '<':
            strcpy(buf, "&lt;");
            break;
 
        case '>':
            strcpy(buf, "&gt;");
            break;
 
        default:
            sprintf(buf, "%c", *tmp);
        }
 
        ast_str_append(&dst, 0, "%s", buf);
    }
 
    return dst;
}
 
static struct ast_str *epoch_to_exchange_time(struct ast_str *dst, time_t epoch)
{
    icaltimezone *utc = icaltimezone_get_utc_timezone();
    icaltimetype tt = icaltime_from_timet_with_zone(epoch, 0, utc);
    char tmp[30];
    int i;
 
    ast_copy_string(tmp, icaltime_as_ical_string(tt), sizeof(tmp));
    for (i = 0; tmp[i]; i++) {
        ast_str_append(&dst, 0, "%c", tmp[i]);
        if (i == 3 || i == 5)
            ast_str_append(&dst, 0, "%c", '-');
        if (i == 10 || i == 12)
            ast_str_append(&dst, 0, "%c", ':');
        if (i == 14)
            ast_str_append(&dst, 0, "%s", ".000");
    }
 
    return dst;
}
 
static struct ast_str *bs_to_exchange_bs(struct ast_str *dst, enum ast_calendar_busy_state bs)
{
    switch (bs) {
    case AST_CALENDAR_BS_BUSY:
        ast_str_set(&dst, 0, "%s", "BUSY");
        break;
 
    case AST_CALENDAR_BS_BUSY_TENTATIVE:
        ast_str_set(&dst, 0, "%s", "TENTATIVE");
        break;
 
    default:
        ast_str_set(&dst, 0, "%s", "FREE");
    }
 
    return dst;
}
 
static int fetch_response_reader(void *data, const char *block, size_t len)
{
    struct ast_str **response = data;
    unsigned char *tmp;
 
    if (!(tmp = ast_malloc(len + 1))) {
        return -1;
    }
    memcpy(tmp, block, len);
    tmp[len] = '\0';
    ast_str_append(response, 0, "%s", tmp);
    ast_free(tmp);
 
    return 0;
}
 
static int auth_credentials(void *userdata, const char *realm, int attempts, char *username, char *secret)
{
    struct exchangecal_pvt *pvt = userdata;
 
    if (attempts > 1) {
        ast_log(LOG_WARNING, "Invalid username or password for Exchange calendar '%s'\n", pvt->owner->name);
        return -1;
    }
 
    ne_strnzcpy(username, pvt->user, NE_ABUFSIZ);
    ne_strnzcpy(secret, pvt->secret, NE_ABUFSIZ);
 
    return 0;
}
 
static struct ast_str *exchangecal_request(struct exchangecal_pvt *pvt, const char *method, struct ast_str *req_body, struct ast_str *subdir)
{
    struct ast_str *response;
    ne_request *req;
    int ret;
    char buf[1000];
 
    if (!pvt) {
        ast_log(LOG_ERROR, "There is no private!\n");
        return NULL;
    }
 
    if (!(response = ast_str_create(512))) {
        ast_log(LOG_ERROR, "Could not allocate memory for response.\n");
        return NULL;
    }
 
    snprintf(buf, sizeof(buf), "%s%s", pvt->uri.path, subdir ? ast_str_buffer(subdir) : "");
 
    req = ne_request_create(pvt->session, method, buf);
    ne_add_response_body_reader(req, ne_accept_2xx, fetch_response_reader, &response);
    ne_set_request_body_buffer(req, ast_str_buffer(req_body), ast_str_strlen(req_body));
    ne_add_request_header(req, "Content-type", "text/xml");
 
    ret = ne_request_dispatch(req);
    ne_request_destroy(req);
 
    if (ret != NE_OK || !ast_str_strlen(response)) {
        ast_log(LOG_WARNING, "Unknown response to CalDAV calendar %s, request %s to %s: %s\n", pvt->owner->name, method, pvt->url, ne_get_error(pvt->session));
        ast_free(response);
        return NULL;
    }
 
    return response;
}
 
static int exchangecal_write_event(struct ast_calendar_event *event)
{
    struct ast_str *body = NULL;
    struct ast_str *response = NULL;
    struct ast_str *subdir = NULL;
    struct ast_str *uid = NULL;
    struct ast_str *summary = NULL;
    struct ast_str *description = NULL;
    struct ast_str *organizer = NULL;
    struct ast_str *location = NULL;
    struct ast_str *start = NULL;
    struct ast_str *end = NULL;
    struct ast_str *busystate = NULL;
    int ret = -1;
 
    if (!event) {
        ast_log(LOG_WARNING, "No event passed!\n");
        return -1;
    }
 
    if (!(event->start && event->end)) {
        ast_log(LOG_WARNING, "The event must contain a start and an end\n");
        return -1;
    }
    if (!(body = ast_str_create(512)) ||
        !(subdir = ast_str_create(32))) {
        ast_log(LOG_ERROR, "Could not allocate memory for request!\n");
        goto write_cleanup;
    }
 
    if (!(uid = ast_str_create(AST_UUID_STR_LEN)) ||
        !(summary = ast_str_create(32)) ||
        !(description = ast_str_create(32)) ||
        !(organizer = ast_str_create(32)) ||
        !(location = ast_str_create(32)) ||
        !(start = ast_str_create(32)) ||
        !(end = ast_str_create(32)) ||
        !(busystate = ast_str_create(32))) {
        ast_log(LOG_ERROR, "Unable to allocate memory for request values\n");
        goto write_cleanup;
    }
 
    if (ast_strlen_zero(event->uid)) {
        uid = generate_exchange_uuid(uid);
    } else {
        ast_str_set(&uid, AST_UUID_STR_LEN, "%s", event->uid);
    }
 
    if (!is_valid_uuid(uid)) {
        ast_log(LOG_WARNING, "An invalid uid was provided, you may leave this field blank to have one generated for you\n");
        goto write_cleanup;
    }
 
    summary = xml_encode_str(summary, event->summary);
    description = xml_encode_str(description, event->description);
    organizer = xml_encode_str(organizer, event->organizer);
    location = xml_encode_str(location, event->location);
    start = epoch_to_exchange_time(start, event->start);
    end = epoch_to_exchange_time(end, event->end);
    busystate = bs_to_exchange_bs(busystate, event->busy_state);
 
    ast_str_append(&body, 0,
        "<?xml version=\"1.0\"?>\n"
        "<a:propertyupdate\n"
        "  xmlns:a=\"DAV:\"\n"
        "  xmlns:e=\"http://schemas.microsoft.com/exchange/\"\n"
        "  xmlns:mapi=\"http://schemas.microsoft.com/mapi/\"\n"
        "  xmlns:mapit=\"http://schemas.microsoft.com/mapi/proptag/\"\n"
        "  xmlns:x=\"xml:\" xmlns:cal=\"urn:schemas:calendar:\"\n"
        "  xmlns:dt=\"uuid:%s/\"\n" /* uid */
        "  xmlns:header=\"urn:schemas:mailheader:\"\n"
        "  xmlns:mail=\"urn:schemas:httpmail:\"\n"
        ">\n"
        "    <a:set>\n"
        "      <a:prop>\n"
        "        <a:contentclass>urn:content-classes:appointment</a:contentclass>\n"
        "        <e:outlookmessageclass>IPM.Appointment</e:outlookmessageclass>\n"
        "        <mail:subject>%s</mail:subject>\n" /* summary */
        "        <mail:description>%s</mail:description>\n" /* description */
        "        <header:to>%s</header:to>\n" /* organizer */
        "        <cal:location>%s</cal:location>\n" /* location */
        "        <cal:dtstart dt:dt=\"dateTime.tz\">%s</cal:dtstart>\n" /* start */
        "        <cal:dtend dt:dt=\"dateTime.tz\">%s</cal:dtend>\n" /* end */
        "        <cal:instancetype dt:dt=\"int\">0</cal:instancetype>\n"
        "        <cal:busystatus>%s</cal:busystatus>\n" /* busy_state (BUSY, FREE, BUSY_TENTATIVE) */
        "        <cal:meetingstatus>CONFIRMED</cal:meetingstatus>\n"
        "        <cal:alldayevent dt:dt=\"boolean\">0</cal:alldayevent>\n" /* XXX need to add event support for all day events */
        "        <cal:responserequested dt:dt=\"boolean\">0</cal:responserequested>\n"
        "        <mapi:finvited dt:dt=\"boolean\">1</mapi:finvited>\n"
        "      </a:prop>\n"
        "    </a:set>\n"
        "</a:propertyupdate>\n",
        ast_str_buffer(uid),
        ast_str_buffer(summary),
        ast_str_buffer(description),
        ast_str_buffer(organizer),
        ast_str_buffer(location),
        ast_str_buffer(start),
        ast_str_buffer(end),
        ast_str_buffer(busystate));
    ast_verb(0, "\n\n%s\n\n", ast_str_buffer(body));
    ast_str_set(&subdir, 0, "/Calendar/%s.eml", ast_str_buffer(uid));
 
    if ((response = exchangecal_request(event->owner->tech_pvt, "PROPPATCH", body, subdir))) {
        ret = 0;
    }
 
write_cleanup:
    ast_free(uid);
    ast_free(summary);
    ast_free(description);
    ast_free(organizer);
    ast_free(location);
    ast_free(start);
    ast_free(end);
    ast_free(busystate);
    ast_free(body);
    ast_free(response);
    ast_free(subdir);
 
    return ret;
}
 
 
static struct ast_str *exchangecal_get_events_between(struct exchangecal_pvt *pvt, time_t start_time, time_t end_time)
{
    struct ast_str *body, *response;
    char start[80], end[80];
    struct timeval tv = {0,};
    struct ast_tm tm;
 
    tv.tv_sec = start_time;
    ast_localtime(&tv, &tm, "UTC");
    ast_strftime(start, sizeof(start), "%Y/%m/%d %T", &tm);
 
    tv.tv_sec = end_time;
    ast_localtime(&tv, &tm, "UTC");
    ast_strftime(end, sizeof(end), "%Y/%m/%d %T", &tm);
 
    if (!(body = ast_str_create(512))) {
        ast_log(LOG_ERROR, "Could not allocate memory for body of request!\n");
        return NULL;
    }
 
    ast_str_append(&body, 0,
        "<?xml version=\"1.0\"?>\n"
        "<g:searchrequest xmlns:g=\"DAV:\">\n"
        "        <g:sql> SELECT \"urn:schemas:calendar:location\", \"urn:schemas:httpmail:subject\",\n"
        "                \"urn:schemas:calendar:dtstart\", \"urn:schemas:calendar:dtend\",\n"
        "                \"urn:schemas:calendar:busystatus\", \"urn:schemas:calendar:instancetype\",\n"
        "                \"urn:schemas:calendar:uid\", \"urn:schemas:httpmail:textdescription\",\n"
        "                \"urn:schemas:calendar:organizer\", \"urn:schemas:calendar:reminderoffset\"\n"
        "                FROM Scope('SHALLOW TRAVERSAL OF \"%s/Calendar\"')\n"
        "                WHERE NOT \"urn:schemas:calendar:instancetype\" = 1\n"
        "                AND \"DAV:contentclass\" = 'urn:content-classes:appointment'\n"
        "                AND NOT (\"urn:schemas:calendar:dtend\" &lt; '%s'\n"
        "                OR \"urn:schemas:calendar:dtstart\" &gt; '%s')\n"
        "                ORDER BY \"urn:schemas:calendar:dtstart\" ASC\n"
        "         </g:sql>\n"
        "</g:searchrequest>\n", pvt->url, start, end);
 
    ast_debug(5, "Request:\n%s\n", ast_str_buffer(body));
    response = exchangecal_request(pvt, "SEARCH", body, NULL);
    ast_debug(5, "Response:\n%s\n", ast_str_buffer(response));
    ast_free(body);
 
    return response;
}
 
static int update_exchangecal(struct exchangecal_pvt *pvt)
{
    struct xmlstate state;
    struct timeval now = ast_tvnow();
    time_t start, end;
    struct ast_str *response;
    iksparser *p;
 
    state.pvt = pvt;
    start = now.tv_sec;
    end = now.tv_sec + 60 * pvt->owner->timeframe;
    if (!(response = exchangecal_get_events_between(pvt, start, end))) {
        return -1;
    }
 
    p = iks_sax_new(&state, parse_tag, parse_cdata);
    iks_parse(p, ast_str_buffer(response), ast_str_strlen(response), 1);
    ast_calendar_merge_events(pvt->owner, pvt->events);
    ast_free(response);
 
    return 0;
}
 
static void *exchangecal_load_calendar(void *void_data)
{
    struct exchangecal_pvt *pvt;
    const struct ast_config *cfg;
    struct ast_variable *v;
    struct ast_calendar *cal = void_data;
    ast_mutex_t refreshlock;
 
    if (!(cal && (cfg = ast_calendar_config_acquire()))) {
        ast_log(LOG_ERROR, "You must enable calendar support for res_exchangecal to load\n");
        return NULL;
    }
 
    if (ao2_trylock(cal)) {
        if (cal->unloading) {
            ast_log(LOG_WARNING, "Unloading module, load_calendar cancelled.\n");
        } else {
            ast_log(LOG_WARNING, "Could not lock calendar, aborting!\n");
        }
        ast_calendar_config_release();
        return NULL;
    }
 
    if (!(pvt = ao2_alloc(sizeof(*pvt), exchangecal_destructor))) {
        ast_log(LOG_ERROR, "Could not allocate exchangecal_pvt structure for calendar: %s\n", cal->name);
        ast_calendar_config_release();
        return NULL;
    }
 
    pvt->owner = cal;
 
    if (!(pvt->events = ast_calendar_event_container_alloc())) {
        ast_log(LOG_ERROR, "Could not allocate space for fetching events for calendar: %s\n", cal->name);
        pvt = unref_exchangecal(pvt);
        ao2_unlock(cal);
        ast_calendar_config_release();
        return NULL;
    }
 
    if (ast_string_field_init(pvt, 32)) {
        ast_log(LOG_ERROR, "Couldn't allocate string field space for calendar: %s\n", cal->name);
        pvt = unref_exchangecal(pvt);
        ao2_unlock(cal);
        ast_calendar_config_release();
        return NULL;
    }
 
    for (v = ast_variable_browse(cfg, cal->name); v; v = v->next) {
        if (!strcasecmp(v->name, "url")) {
            ast_string_field_set(pvt, url, v->value);
        } else if (!strcasecmp(v->name, "user")) {
            ast_string_field_set(pvt, user, v->value);
        } else if (!strcasecmp(v->name, "secret")) {
            ast_string_field_set(pvt, secret, v->value);
        }
    }
 
    ast_calendar_config_release();
 
    if (ast_strlen_zero(pvt->url)) {
        ast_log(LOG_WARNING, "No URL was specified for Exchange calendar '%s' - skipping.\n", cal->name);
        pvt = unref_exchangecal(pvt);
        ao2_unlock(cal);
        return NULL;
    }
 
    if (ne_uri_parse(pvt->url, &pvt->uri) || pvt->uri.host == NULL || pvt->uri.path == NULL) {
        ast_log(LOG_WARNING, "Could not parse url '%s' for Exchange calendar '%s' - skipping.\n", pvt->url, cal->name);
        pvt = unref_exchangecal(pvt);
        ao2_unlock(cal);
        return NULL;
    }
 
    if (pvt->uri.scheme == NULL) {
        pvt->uri.scheme = "http";
    }
 
    if (pvt->uri.port == 0) {
        pvt->uri.port = ne_uri_defaultport(pvt->uri.scheme);
    }
 
    pvt->session = ne_session_create(pvt->uri.scheme, pvt->uri.host, pvt->uri.port);
    ne_redirect_register(pvt->session);
    ne_set_server_auth(pvt->session, auth_credentials, pvt);
    if (!strcasecmp(pvt->uri.scheme, "https")) {
        ne_ssl_trust_default_ca(pvt->session);
    }
 
    cal->tech_pvt = pvt;
 
    ast_mutex_init(&refreshlock);
 
    /* Load it the first time */
    update_exchangecal(pvt);
 
    ao2_unlock(cal);
 
    /* The only writing from another thread will be if unload is true */
    for (;;) {
        struct timeval tv = ast_tvnow();
        struct timespec ts = {0,};
 
        ts.tv_sec = tv.tv_sec + (60 * pvt->owner->refresh);
 
        ast_mutex_lock(&refreshlock);
        while (!pvt->owner->unloading) {
            if (ast_cond_timedwait(&pvt->owner->unload, &refreshlock, &ts) == ETIMEDOUT) {
                break;
            }
        }
        ast_mutex_unlock(&refreshlock);
 
        if (pvt->owner->unloading) {
            ast_debug(10, "Skipping refresh since we got a shutdown signal\n");
            return NULL;
        }
 
        ast_debug(10, "Refreshing after %d minute timeout\n", pvt->owner->refresh);
 
        update_exchangecal(pvt);
    }
 
    return NULL;
}
 
static int load_module(void)
{
    ne_sock_init();
    if (ast_calendar_register(&exchangecal_tech)) {
        ne_sock_exit();
        return AST_MODULE_LOAD_DECLINE;
    }
 
    return AST_MODULE_LOAD_SUCCESS;
}
 
static int unload_module(void)
{
    ast_calendar_unregister(&exchangecal_tech);
    ne_sock_exit();
    return 0;
}
 
AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_LOAD_ORDER, "Asterisk MS Exchange Calendar Integration",
    .support_level = AST_MODULE_SUPPORT_EXTENDED,
    .load = load_module,
    .unload = unload_module,
    .load_pri = AST_MODPRI_DEVSTATE_PLUGIN,
    .requires = "res_calendar",
);