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