webcit/ical_dezonify.c

   1
   2 /*
   3  * Function to go through an ical component set and convert all non-UTC
   4  * date/time properties to UTC.  It also strips out any VTIMEZONE
   5  * subcomponents afterwards, because they're irrelevant.
   6  *
   7  * Everything here will work on both a fully encapsulated VCALENDAR component
   8  * or any type of subcomponent.
   9  */
  10
  11 #include "webcit.h"
  12 #include "webserver.h"
  13
  14 /*
  15  * Figure out which time zone needs to be used for timestamps that are
  16  * not UTC and do not have a time zone specified.
  17  *
  18  */
  19 icaltimezone *get_default_icaltimezone(void) {
  20
  21         icaltimezone *zone = NULL;
  22         const char *default_zone_name = ChrPtr(WC->serv_info->serv_default_cal_zone);
  23
  24         if (!zone) {
  25                 zone = icaltimezone_get_builtin_timezone(default_zone_name);
  26         }
  27         if (!zone) {
  28                 syslog(LOG_WARNING, "Unable to load '%s' time zone.  Defaulting to UTC.\n", default_zone_name);
  29                 zone = icaltimezone_get_utc_timezone();
  30         }
  31         if (!zone) {
  32                 syslog(LOG_ERR, "Unable to load UTC time zone!\n");
  33         }
  34         return zone;
  35 }
  36
  37
  38 /*
  39  * Back end function for ical_dezonify()
  40  *
  41  * We supply this with the master component, the relevant component,
  42  * and the property (which will be a DTSTART, DTEND, etc.)
  43  * which we want to convert to UTC.
  44  */
  45 void ical_dezonify_backend(icalcomponent * cal, icalcomponent * rcal, icalproperty * prop) {
  46
  47         icaltimezone *t = NULL;
  48         icalparameter *param;
  49         const char *tzid = NULL;
  50         struct icaltimetype TheTime;
  51         int utc_declared_as_tzid = 0;   /* Component declared 'TZID=GMT' instead of using Z syntax */
  52
  53         /* Give me nothing and I will give you nothing in return. */
  54         if (cal == NULL)
  55                 return;
  56
  57         /* Hunt for a TZID parameter in this property. */
  58         param = icalproperty_get_first_parameter(prop, ICAL_TZID_PARAMETER);
  59
  60         /* Get the stringish name of this TZID. */
  61         if (param != NULL) {
  62                 tzid = icalparameter_get_tzid(param);
  63
  64                 /* Convert it to an icaltimezone type. */
  65                 if (tzid != NULL) {
  66 #ifdef DBG_ICAL
  67                         syslog(LOG_DEBUG, "                * Stringy supplied timezone is: '%s'\n", tzid);
  68 #endif
  69                         if ((!strcasecmp(tzid, "UTC")) || (!strcasecmp(tzid, "GMT"))) {
  70                                 utc_declared_as_tzid = 1;
  71 #ifdef DBG_ICAL
  72                                 syslog(LOG_DEBUG, "                * ...and we handle that internally.\n");
  73 #endif
  74                         }
  75                         else {
  76                                 /* try attached first */
  77                                 t = icalcomponent_get_timezone(cal, tzid);
  78 #ifdef DBG_ICAL
  79                                 syslog(LOG_DEBUG, "                * ...and I %s have tzdata for that zone.\n",
  80                                        (t ? "DO" : "DO NOT")
  81                                     );
  82 #endif
  83                                 /* then try built-in timezones */
  84                                 if (!t) {
  85                                         t = icaltimezone_get_builtin_timezone(tzid);
  86 #ifdef DBG_ICAL
  87                                         if (t) {
  88                                                 syslog(LOG_DEBUG, "                * Using system tzdata!\n");
  89                                         }
  90 #endif
  91                                 }
  92                         }
  93                 }
  94
  95         }
  96
  97         /* Now we know the timezone.  Convert to UTC. */
  98
  99         if (icalproperty_isa(prop) == ICAL_DTSTART_PROPERTY) {
 100                 TheTime = icalproperty_get_dtstart(prop);
 101         }
 102         else if (icalproperty_isa(prop) == ICAL_DTEND_PROPERTY) {
 103                 TheTime = icalproperty_get_dtend(prop);
 104         }
 105         else if (icalproperty_isa(prop) == ICAL_DUE_PROPERTY) {
 106                 TheTime = icalproperty_get_due(prop);
 107         }
 108         else if (icalproperty_isa(prop) == ICAL_EXDATE_PROPERTY) {
 109                 TheTime = icalproperty_get_exdate(prop);
 110         }
 111         else {
 112                 return;
 113         }
 114
 115 #ifdef DBG_ICAL
 116         syslog(LOG_DEBUG, "                * Was: %s\n", icaltime_as_ical_string(TheTime));
 117 #endif
 118
 119         if (icaltime_is_utc(TheTime)) {
 120 #ifdef DBG_ICAL
 121                 syslog(LOG_DEBUG, "                * This property is ALREADY UTC.\n");
 122 #endif
 123         }
 124
 125         else if (utc_declared_as_tzid) {
 126 #ifdef DBG_ICAL
 127                 syslog(LOG_DEBUG, "                * Replacing '%s' TZID with 'Z' suffix.\n", tzid);
 128 #endif
 129                 TheTime.zone = icaltimezone_get_utc_timezone();
 130         }
 131
 132         else {
 133                 /* Do the conversion. */
 134                 if (t != NULL) {
 135 #ifdef DBG_ICAL
 136                         syslog(LOG_DEBUG, "                * Timezone prop found.  Converting to UTC.\n");
 137 #endif
 138                 }
 139                 else {
 140 #ifdef DBG_ICAL
 141                         syslog(LOG_DEBUG, "                * Converting default timezone to UTC.\n");
 142 #endif
 143                 }
 144
 145                 if (t == NULL) {
 146                         t = get_default_icaltimezone();
 147                 }
 148                 icaltimezone_convert_time(&TheTime, t, icaltimezone_get_utc_timezone());
 149                 TheTime.zone = icaltimezone_get_utc_timezone();
 150         }
 151
 152         icalproperty_remove_parameter_by_kind(prop, ICAL_TZID_PARAMETER);
 153 #ifdef DBG_ICAL
 154         syslog(LOG_DEBUG, "                * Now: %s\n", icaltime_as_ical_string(TheTime));
 155 #endif
 156
 157         /* Now add the converted property back in. */
 158         if (icalproperty_isa(prop) == ICAL_DTSTART_PROPERTY) {
 159                 icalproperty_set_dtstart(prop, TheTime);
 160         }
 161         else if (icalproperty_isa(prop) == ICAL_DTEND_PROPERTY) {
 162                 icalproperty_set_dtend(prop, TheTime);
 163         }
 164         else if (icalproperty_isa(prop) == ICAL_DUE_PROPERTY) {
 165                 icalproperty_set_due(prop, TheTime);
 166         }
 167         else if (icalproperty_isa(prop) == ICAL_EXDATE_PROPERTY) {
 168                 icalproperty_set_exdate(prop, TheTime);
 169         }
 170 }
 171
 172
 173 /*
 174  * Recursive portion of ical_dezonify()
 175  */
 176 void ical_dezonify_recurse(icalcomponent * cal, icalcomponent * rcal) {
 177         icalcomponent *c;
 178         icalproperty *p;
 179
 180         /*
 181          * Recurse through all subcomponents *except* VTIMEZONE ones.
 182          */
 183         for (c = icalcomponent_get_first_component(rcal, ICAL_ANY_COMPONENT);
 184              c != NULL; c = icalcomponent_get_next_component(rcal, ICAL_ANY_COMPONENT)
 185             ) {
 186                 if (icalcomponent_isa(c) != ICAL_VTIMEZONE_COMPONENT) {
 187                         ical_dezonify_recurse(cal, c);
 188                 }
 189         }
 190
 191         /*
 192          * Now look for DTSTART and DTEND properties
 193          */
 194         for (p = icalcomponent_get_first_property(rcal, ICAL_ANY_PROPERTY);
 195              p != NULL; p = icalcomponent_get_next_property(rcal, ICAL_ANY_PROPERTY)
 196             ) {
 197                 if ((icalproperty_isa(p) == ICAL_DTSTART_PROPERTY)
 198                     || (icalproperty_isa(p) == ICAL_DTEND_PROPERTY)
 199                     || (icalproperty_isa(p) == ICAL_DUE_PROPERTY)
 200                     || (icalproperty_isa(p) == ICAL_EXDATE_PROPERTY)
 201                     ) {
 202                         ical_dezonify_backend(cal, rcal, p);
 203                 }
 204         }
 205 }
 206
 207
 208 /*
 209  * Convert all DTSTART and DTEND properties in all subcomponents to UTC.
 210  * This function will search any VTIMEZONE subcomponents to learn the
 211  * relevant timezone information.
 212  */
 213 void ical_dezonify(icalcomponent * cal) {
 214         icalcomponent *vt = NULL;
 215
 216 #ifdef DBG_ICAL
 217         syslog(LOG_DEBUG, "ical_dezonify() started\n");
 218 #endif
 219
 220         /* Convert all times to UTC */
 221         ical_dezonify_recurse(cal, cal);
 222
 223         /* Strip out VTIMEZONE subcomponents -- we don't need them anymore */
 224         while (vt = icalcomponent_get_first_component(cal, ICAL_VTIMEZONE_COMPONENT), vt != NULL) {
 225                 icalcomponent_remove_component(cal, vt);
 226                 icalcomponent_free(vt);
 227         }
 228
 229 #ifdef DBG_ICAL
 230         syslog(LOG_DEBUG, "ical_dezonify() completed\n");
 231 #endif
 232 }