res_calendar: Various fixes

* The way that we were looking at XML elements for CalDAV was extremely
  fragile, so use SAX2 for increased robustness.

* Don't complain about a 'channel' not be specified if autoreminder is
  not set. Assume that if 'channel' is not set, we don't want to be
  notified.

* Fix some truncated CLI output in 'calendar show calendar' and make the
  'Autoreminder' description a bit more clear

ASTERISK-24588 #close
Reported by: Stefan Gofferje

ASTERISK-25523 #close
Reported by: Jesper

Change-Id: I200d11afca6a47e7d97888f286977e2e69874b2c

res/res_calendar.c

@@ -482,6 +482,13 @@ static struct ast_calendar *build_calendar(struct ast_config *cfg, const char *c
 		}
 	}
 
+	if (cal->autoreminder && ast_strlen_zero(cal->notify_channel)) {
+		ast_log(LOG_WARNING,
+				"You have set 'autoreminder' but not 'channel' for calendar '%s.' "
+				"Notifications will not occur.\n",
+				cal->name);
+	}
+
 	if (new_calendar) {
 		cal->thread = AST_PTHREADT_NULL;
 		ast_cond_init(&cal->unload, NULL);
@@ -489,7 +496,7 @@ static struct ast_calendar *build_calendar(struct ast_config *cfg, const char *c
 		if (ast_pthread_create(&cal->thread, NULL, cal->tech->load_calendar, cal)) {
 			/* If we start failing to create threads, go ahead and return NULL
 			 * and the tech module will be unregistered
-			 */ 
+			 */
 			ao2_unlink(calendars, cal);
 			cal = unref_calendar(cal);
 		}
@@ -948,7 +955,7 @@ static int schedule_calendar_event(struct ast_calendar *cal, struct ast_calendar
 	event = cmp_event ? cmp_event : old_event;
 
 	ao2_lock(event);
-	if (!cmp_event || old_event->alarm != event->alarm) {
+	if (!ast_strlen_zero(cal->notify_channel) && (!cmp_event || old_event->alarm != event->alarm)) {
 		changed = 1;
 		if (cal->autoreminder) {
 			alarm_notify_sched = (event->start - (60 * cal->autoreminder) - now.tv_sec) * 1000;
@@ -957,7 +964,7 @@ static int schedule_calendar_event(struct ast_calendar *cal, struct ast_calendar
 		}
 
 		/* For now, send the notification if we missed it, but the meeting hasn't happened yet */
-		if (event->start >=  now.tv_sec) {
+		if (event->start >= now.tv_sec) {
 			if (alarm_notify_sched <= 0) {
 				alarm_notify_sched = 1;
 			}
@@ -1590,7 +1597,7 @@ static char *epoch_to_string(char *buf, size_t buflen, time_t epoch)
 
 static char *handle_show_calendar(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a)
 {
-#define FORMAT "%-17.17s : %-20.20s\n"
+#define FORMAT  "%-18.18s : %-20.20s\n"
 #define FORMAT2 "%-12.12s: %-40.60s\n"
 	struct ao2_iterator i;
 	struct ast_calendar *cal;
@@ -1639,7 +1646,13 @@ static char *handle_show_calendar(struct ast_cli_entry *e, int cmd, struct ast_c
 	ast_cli(a->fd, FORMAT, "Notify appdata", cal->notify_appdata);
 	ast_cli(a->fd, "%-17.17s : %d\n", "Refresh time", cal->refresh);
 	ast_cli(a->fd, "%-17.17s : %d\n", "Timeframe", cal->timeframe);
-	ast_cli(a->fd, "%-17.17s : %d\n", "Autoreminder", cal->autoreminder);
+
+	if (cal->autoreminder) {
+		ast_cli(a->fd, "%-17.17s : %d minutes before event\n", "Autoreminder", cal->autoreminder);
+	} else {
+		ast_cli(a->fd, "%-17.17s : None\n", "Autoreminder");
+	}
+
 	ast_cli(a->fd, "%s\n", "Events");
 	ast_cli(a->fd, "%s\n", "------");
 

res/res_calendar_caldav.c

@@ -158,6 +158,7 @@ static struct ast_str *caldav_request(struct caldav_pvt *pvt, const char *method
 	ne_add_response_body_reader(req, debug_response_handler, 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", ast_strlen_zero(content_type) ? "text/xml" : content_type);
+	ne_add_request_header(req, "Depth", "1");
 
 	ret = ne_request_dispatch(req);
 	ne_request_destroy(req);
@@ -478,17 +479,26 @@ struct xmlstate {
 	time_t end;
 };
 
-static void handle_start_element(void *data, const xmlChar *fullname, const xmlChar **atts)
+static const xmlChar *caldav_node_localname = BAD_CAST "calendar-data";
+static const xmlChar *caldav_node_nsuri     = BAD_CAST "urn:ietf:params:xml:ns:caldav";
+
+static void handle_start_element(void *data,
+								 const xmlChar *localname, const xmlChar *prefix, const xmlChar *uri,
+								 int nb_namespaces, const xmlChar **namespaces,
+								 int nb_attributes, int nb_defaulted, const xmlChar **attributes)
 {
 	struct xmlstate *state = data;
 
-	if (!xmlStrcasecmp(fullname, BAD_CAST "C:calendar-data") || !xmlStrcasecmp(fullname, BAD_CAST "caldav:calendar-data")) {
+	if (xmlStrcmp(localname, caldav_node_localname) || xmlStrcmp(uri, caldav_node_nsuri)) {
-		state->in_caldata = 1;
+		return;
-		ast_str_reset(state->cdata);
 	}
+
+	state->in_caldata = 1;
+	ast_str_reset(state->cdata);
 }
 
-static void handle_end_element(void *data, const xmlChar *name)
+static void handle_end_element(void *data,
+							   const xmlChar *localname, const xmlChar *prefix, const xmlChar *uri)
 {
 	struct xmlstate *state = data;
 	struct icaltimetype start, end;
@@ -496,7 +506,7 @@ static void handle_end_element(void *data, const xmlChar *name)
 	icalcomponent *iter;
 	icalcomponent *comp;
 
-	if (xmlStrcasecmp(name, BAD_CAST "C:calendar-data") && xmlStrcasecmp(name, BAD_CAST "caldav:calendar-data")) {
+	if (xmlStrcmp(localname, caldav_node_localname) || xmlStrcmp(uri, caldav_node_nsuri)) {
 		return;
 	}
 
@@ -559,9 +569,23 @@ static int update_caldav(struct caldav_pvt *pvt)
 	state.start = start;
 	state.end = end;
 
+	/*
+	 * We want SAX2, so you assume that we want to call xmlSAXVersion() here, and
+	 * that certainly seems like the right thing to do, but the default SAX
+	 * handling functions assume that the 'data' pointer is going to be a
+	 * xmlParserCtxtPtr, not a user data pointer, so we have to make sure that we
+	 * are only calling the handlers that we control.
+	 *
+	 * So instead we hack things up a bit, clearing the struct and then assigning
+	 * the magic number manually.
+	 *
+	 * There may be a cleaner way to do this, but frankly the libxml2 docs are
+	 * pretty sparse.
+	 */
 	memset(&saxHandler, 0, sizeof(saxHandler));
-	saxHandler.startElement = handle_start_element;
+	saxHandler.initialized = XML_SAX2_MAGIC;
-	saxHandler.endElement = handle_end_element;
+	saxHandler.startElementNs = handle_start_element;
+	saxHandler.endElementNs = handle_end_element;
 	saxHandler.characters = handle_characters;
 
 	xmlSAXUserParseMemory(&saxHandler, &state, ast_str_buffer(response), ast_str_strlen(response));