webcit/ical_dezonify.c

   1 // Function to go through an ical component set and convert all non-UTC
   2 // date/time properties to UTC.  It also strips out any VTIMEZONE
   3 // subcomponents afterwards, because they're irrelevant.
   4 //
   5 // Everything here will work on both components and subcomponents.  If subcomponents are discovered it will recurse through them.
   6 //
   7 // Copyright (c) 2002-2024 by the citadel.org team (Art Cancro et al)
   8 // This program is open source software.  Use, duplication, or disclosure is subject to the GNU General Public License v3.
   9
  10 #include "webcit.h"
  11 #include "webserver.h"
  12
  13 // Figure out which time zone needs to be used for timestamps that are
  14 // not UTC and do not have a time zone specified.
  15 icaltimezone *get_default_icaltimezone(void) {
  16
  17         icaltimezone *zone = NULL;
  18         const char *default_zone_name = ChrPtr(WC->serv_info->serv_default_cal_zone);
  19
  20         if (!zone) {
  21                 zone = icaltimezone_get_builtin_timezone(default_zone_name);
  22         }
  23         if (!zone) {
  24                 syslog(LOG_WARNING, "Unable to load '%s' time zone.  Defaulting to UTC.\n", default_zone_name);
  25                 zone = icaltimezone_get_utc_timezone();
  26         }
  27         if (!zone) {
  28                 syslog(LOG_ERR, "Unable to load UTC time zone!\n");
  29         }
  30         return zone;
  31 }
  32
  33
  34 // Back end function for ical_dezonify()
  35 //
  36 // We supply this with the master component, the relevant component,
  37 // and the property (which will be a DTSTART, DTEND, etc.)
  38 // which we want to convert to UTC.
  39 void ical_dezonify_backend(icalcomponent *cal, icalcomponent *rcal, icalproperty *prop) {
  40
  41         icaltimezone *t = NULL;
  42         icalparameter *param;
  43         const char *tzid = NULL;
  44         struct icaltimetype TheTime;
  45         int utc_declared_as_tzid = 0;   // Component declared 'TZID=GMT' instead of using Z syntax
  46
  47         // Give me nothing and I will give you nothing in return.
  48         if (cal == NULL) return;
  49
  50         // Hunt for a TZID parameter in this property.
  51         param = icalproperty_get_first_parameter(prop, ICAL_TZID_PARAMETER);
  52
  53         // Get the stringish name of this TZID.
  54         if (param != NULL) {
  55                 tzid = icalparameter_get_tzid(param);
  56
  57                 // Convert it to an icaltimezone type.
  58                 if (tzid != NULL) {
  59 #ifdef DBG_ICAL
  60                         syslog(LOG_DEBUG, "                * Stringy supplied timezone is: '%s'\n", tzid);
  61 #endif
  62                         if ( (!strcasecmp(tzid, "UTC")) || (!strcasecmp(tzid, "GMT")) ) {
  63                                 utc_declared_as_tzid = 1;
  64 #ifdef DBG_ICAL
  65                                 syslog(LOG_DEBUG, "                * ...and we handle that internally.\n");
  66 #endif
  67                         }
  68                         else {
  69                                 // try attached first
  70                                 t = icalcomponent_get_timezone(cal, tzid);
  71 #ifdef DBG_ICAL
  72                                 syslog(LOG_DEBUG, "                * ...and I %s have tzdata for that zone.\n",
  73                                         (t ? "DO" : "DO NOT")
  74                                 );
  75 #endif
  76                                 // then try built-in timezones
  77                                 if (!t) {
  78                                         t = icaltimezone_get_builtin_timezone(tzid);
  79 #ifdef DBG_ICAL
  80                                         if (t) {
  81                                                 syslog(LOG_DEBUG, "                * Using system tzdata!\n");
  82                                         }
  83 #endif
  84                                 }
  85                         }
  86                 }
  87
  88         }
  89
  90         // Now we know the timezone.  Convert to UTC.
  91
  92         if (icalproperty_isa(prop) == ICAL_DTSTART_PROPERTY) {
  93                 TheTime = icalproperty_get_dtstart(prop);
  94         }
  95         else if (icalproperty_isa(prop) == ICAL_DTEND_PROPERTY) {
  96                 TheTime = icalproperty_get_dtend(prop);
  97         }
  98         else if (icalproperty_isa(prop) == ICAL_DUE_PROPERTY) {
  99                 TheTime = icalproperty_get_due(prop);
 100         }
 101         else if (icalproperty_isa(prop) == ICAL_EXDATE_PROPERTY) {
 102                 TheTime = icalproperty_get_exdate(prop);
 103         }
 104         else {
 105                 return;
 106         }
 107
 108 #ifdef DBG_ICAL
 109         syslog(LOG_DEBUG, "                * Was: %s\n", icaltime_as_ical_string(TheTime));
 110 #endif
 111
 112         if (icaltime_is_utc(TheTime)) {
 113 #ifdef DBG_ICAL
 114                 syslog(LOG_DEBUG, "                * This property is ALREADY UTC.\n");
 115 #endif
 116         }
 117
 118         else if (utc_declared_as_tzid) {
 119 #ifdef DBG_ICAL
 120                 syslog(LOG_DEBUG, "                * Replacing '%s' TZID with 'Z' suffix.\n", tzid);
 121 #endif
 122                 TheTime.zone = icaltimezone_get_utc_timezone();
 123         }
 124
 125         else {
 126                 // Do the conversion.
 127                 if (t != NULL) {
 128 #ifdef DBG_ICAL
 129                         syslog(LOG_DEBUG, "                * Timezone prop found.  Converting to UTC.\n");
 130 #endif
 131                 }
 132                 else {
 133 #ifdef DBG_ICAL
 134                         syslog(LOG_DEBUG, "                * Converting default timezone to UTC.\n");
 135 #endif
 136                 }
 137
 138                 if (t == NULL) {
 139                         t = get_default_icaltimezone();
 140                 }
 141                 icaltimezone_convert_time(&TheTime, t, icaltimezone_get_utc_timezone());
 142                 TheTime.zone = icaltimezone_get_utc_timezone();
 143         }
 144
 145         icalproperty_remove_parameter_by_kind(prop, ICAL_TZID_PARAMETER);
 146 #ifdef DBG_ICAL
 147         syslog(LOG_DEBUG, "                * Now: %s\n", icaltime_as_ical_string(TheTime));
 148 #endif
 149
 150         // Now add the converted property back in.
 151         if (icalproperty_isa(prop) == ICAL_DTSTART_PROPERTY) {
 152                 icalproperty_set_dtstart(prop, TheTime);
 153         }
 154         else if (icalproperty_isa(prop) == ICAL_DTEND_PROPERTY) {
 155                 icalproperty_set_dtend(prop, TheTime);
 156         }
 157         else if (icalproperty_isa(prop) == ICAL_DUE_PROPERTY) {
 158                 icalproperty_set_due(prop, TheTime);
 159         }
 160         else if (icalproperty_isa(prop) == ICAL_EXDATE_PROPERTY) {
 161                 icalproperty_set_exdate(prop, TheTime);
 162         }
 163 }
 164
 165
 166 // Recursive portion of ical_dezonify()
 167 void ical_dezonify_recurse(icalcomponent *cal, icalcomponent *rcal) {
 168         icalcomponent *c;
 169         icalproperty *p;
 170
 171         // Recurse through all subcomponents *except* VTIMEZONE ones.
 172         for (   c=icalcomponent_get_first_component(rcal, ICAL_ANY_COMPONENT);
 173                 c != NULL;
 174                 c = icalcomponent_get_next_component(rcal, ICAL_ANY_COMPONENT)
 175         ) {
 176                 if (icalcomponent_isa(c) != ICAL_VTIMEZONE_COMPONENT) {
 177                         ical_dezonify_recurse(cal, c);
 178                 }
 179         }
 180
 181         // Now look for DTSTART and DTEND properties
 182         for (   p=icalcomponent_get_first_property(rcal, ICAL_ANY_PROPERTY);
 183                 p != NULL;
 184                 p = icalcomponent_get_next_property(rcal, ICAL_ANY_PROPERTY)
 185         ) {
 186                 if (
 187                         (icalproperty_isa(p) == ICAL_DTSTART_PROPERTY)
 188                         || (icalproperty_isa(p) == ICAL_DTEND_PROPERTY)
 189                         || (icalproperty_isa(p) == ICAL_DUE_PROPERTY)
 190                         || (icalproperty_isa(p) == ICAL_EXDATE_PROPERTY)
 191                 ) {
 192                         ical_dezonify_backend(cal, rcal, p);
 193                 }
 194         }
 195 }
 196
 197
 198 // Convert all DTSTART and DTEND properties in all subcomponents to UTC.
 199 // This function will search any VTIMEZONE subcomponents to learn the
 200 // relevant timezone information.
 201 void ical_dezonify(icalcomponent *cal) {
 202         icalcomponent *vt = NULL;
 203
 204 #ifdef DBG_ICAL
 205         syslog(LOG_DEBUG, "ical_dezonify() started\n");
 206 #endif
 207
 208         // Convert all times to UTC
 209         ical_dezonify_recurse(cal, cal);
 210
 211         // Strip out VTIMEZONE subcomponents -- we don't need them anymore.
 212         while (vt = icalcomponent_get_first_component(cal, ICAL_VTIMEZONE_COMPONENT), vt != NULL) {
 213                 icalcomponent_remove_component(cal, vt);
 214                 icalcomponent_free(vt);
 215         }
 216
 217 #ifdef DBG_ICAL
 218         syslog(LOG_DEBUG, "ical_dezonify() completed\n");
 219 #endif
 220 }