webcit/ical_dezonify.c

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