src/protocol/date.c

   1 /* Parser of HTTP date */
   2
   3 #ifdef HAVE_CONFIG_H
   4 #include "config.h"
   5 #endif
   6
   7 #include <stdlib.h>
   8 #include <string.h>
   9
  10 #ifdef TIME_WITH_SYS_TIME
  11 #ifdef HAVE_SYS_TIME_H
  12 #include <sys/time.h>
  13 #endif
  14 #ifdef HAVE_TIME_H
  15 #include <time.h>
  16 #endif
  17 #else
  18 #if defined(TM_IN_SYS_TIME) && defined(HAVE_SYS_TIME_H)
  19 #include <sys/time.h>
  20 #elif defined(HAVE_TIME_H)
  21 #include <time.h>
  22 #endif
  23 #endif
  24
  25 #include "elinks.h"
  26
  27 #include "protocol/date.h"
  28 #include "util/conv.h"
  29 #include "util/time.h"
  30
  31 /*
  32  * Sun, 06 Nov 1994 08:49:37 GMT  ; RFC 822, updated by RFC 1123
  33  * Sunday, 06-Nov-94 08:49:37 GMT ; RFC 850, obsoleted by RFC 1036
  34  * Sun Nov  6 08:49:37 1994       ; ANSI C's asctime() format
  35  */
  36
  37 int
  38 parse_year(const unsigned char **date_p, unsigned char *end)
  39 {
  40         const unsigned char *date = *date_p;
  41         int year;
  42
  43         if ((end && date + 1 >= end)
  44             || !isdigit(date[0])
  45             || !isdigit(date[1]))
  46                 return -1;
  47
  48         year = (date[0] - '0') * 10 + date[1] - '0';
  49
  50         if ((!end || date + 3 < end)
  51             && isdigit(date[2])
  52             && isdigit(date[3])) {
  53                 /* Four digits date */
  54                 year = year * 10 + date[2] - '0';
  55                 year = year * 10 + date[3] - '0' - 1900;
  56                 date += 4;
  57
  58         } else if (year < 70) {
  59                 /* Assuming the epoch starting at 1.1.1970 so it's already next
  60                  * century. --wget */
  61                 year += 100;
  62                 date += 2;
  63         }
  64
  65         *date_p = date;
  66         return year;
  67 }
  68
  69 int
  70 parse_month(const unsigned char **buf, unsigned char *end)
  71 {
  72         const unsigned char *month = *buf;
  73         int monthnum;
  74
  75         /* Check that the buffer has atleast 3 chars. */
  76         if ((end && month + 2 > end)
  77             || !month[0] || !month[1] || !month[2])
  78                 return -1;
  79
  80         monthnum = month2num(month);
  81
  82         if (monthnum != -1)
  83                 *buf += 3;
  84
  85         return monthnum;
  86 }
  87
  88
  89 /* Return day number. */
  90 int
  91 parse_day(const unsigned char **date_p, unsigned char *end)
  92 {
  93         const unsigned char *date = *date_p;
  94         int day;
  95
  96         if ((end && date >= end) || !isdigit(*date))
  97                 return 32;
  98         day = *date++ - '0';
  99
 100         if ((!end || date < end) && isdigit(*date)) {
 101                 day = day * 10 + *date++ - '0';
 102         }
 103
 104         *date_p = date;
 105         return day;
 106 }
 107
 108 int
 109 parse_time(const unsigned char **time, struct tm *tm, unsigned char *end)
 110 {
 111         unsigned char h1, h2, m1, m2;
 112         const unsigned char *date = *time;
 113
 114 #define check_time(tm) \
 115         ((tm)->tm_hour <= 23 && (tm)->tm_min <= 59 && (tm)->tm_sec <= 59)
 116
 117         /* Eat HH:MM */
 118         if (end && date + 5 > end)
 119                 return 0;
 120
 121         h1 = *date++; if (!isdigit(h1)) return 0;
 122         h2 = *date++; if (!isdigit(h2)) return 0;
 123
 124         if (*date++ != ':') return 0;
 125
 126         m1 = *date++; if (!isdigit(m1)) return 0;
 127         m2 = *date++; if (!isdigit(m2)) return 0;
 128
 129         tm->tm_hour = (h1 - '0') * 10 + h2 - '0';
 130         tm->tm_min  = (m1 - '0') * 10 + m2 - '0';
 131
 132         /* Eat :SS or [PA]M or nothing */
 133         if (end && date + 2 >= end) {
 134                 *time = date;
 135                 return check_time(tm);
 136         }
 137
 138         if (*date == ':') {
 139                 unsigned char s1, s2;
 140
 141                 date++;
 142
 143                 if (end && date + 2 >= end)
 144                         return 0;
 145
 146                 s1 = *date++; if (!isdigit(s1)) return 0;
 147                 s2 = *date++; if (!isdigit(s2)) return 0;
 148
 149                 tm->tm_sec = (s1 - '0') * 10 + s2 - '0';
 150
 151         } else if (*date == 'A' || *date == 'P') {
 152                 /* Adjust hour from AM/PM. The sequence goes 11:00AM, 12:00PM,
 153                  * 01:00PM ... 11:00PM, 12:00AM, 01:00AM. --wget */
 154                 if (tm->tm_hour == 12)
 155                         tm->tm_hour = 0;
 156
 157                 if (*date++ == 'P')
 158                         tm->tm_hour += 12;
 159
 160                 if (*date++ != 'M')
 161                         return 0;
 162         }
 163
 164         *time = date;
 165
 166         return check_time(tm);
 167 }
 168
 169
 170 static time_t
 171 my_timegm(struct tm *tm)
 172 {
 173         time_t t = 0;
 174
 175         /* Okay, the next part of the code is somehow problematic. Now, we use
 176          * own code for calculating the number of seconds from 1.1.1970,
 177          * brought here by SC from w3m. I don't like it a lot, but it's 100%
 178          * portable, it's faster and it's shorter. --pasky */
 179 #if 0
 180 #ifdef HAVE_TIMEGM
 181         t = timegm(tm);
 182 #else
 183         /* Since mktime thinks we have localtime, we need a wrapper
 184          * to handle GMT. */
 185         /* FIXME: It was reported that it doesn't work somewhere :/. */
 186         {
 187                 unsigned char *tz = getenv("TZ");
 188
 189                 if (tz && *tz) {
 190                         /* Temporary disable timezone in-place. */
 191                         unsigned char tmp = *tz;
 192
 193                         *tz = '\0';
 194                         tzset();
 195
 196                         t = mktime(tm);
 197
 198                         *tz = tmp;
 199                         tzset();
 200
 201                 } else {
 202                         /* Already GMT, cool! */
 203                         t = mktime(tm);
 204                 }
 205         }
 206 #endif
 207 #else
 208         /* Following code was borrowed from w3m, and its developers probably
 209          * borrowed it from somewhere else as well, altough they didn't bother
 210          * to mention that. */ /* Actually, same code appears to be in lynx as
 211          * well.. oh well. :) */
 212         /* See README.timegm for explanation about how this works. */
 213         tm->tm_mon -= 2;
 214         if (tm->tm_mon < 0) {
 215                 tm->tm_mon += 12;
 216                 tm->tm_year--;
 217         }
 218         tm->tm_mon *= 153; tm->tm_mon += 2;
 219         tm->tm_year -= 68;
 220
 221         /* Bug 924: Assumes all years divisible by 4 are leap years,
 222          * even though e.g. 2100 is not.  */
 223         tm->tm_mday += tm->tm_year * 1461 / 4;
 224         tm->tm_mday += ((tm->tm_mon / 5) - 672);
 225
 226         t = ((tm->tm_mday * 60 * 60 * 24) +
 227              (tm->tm_hour * 60 * 60) +
 228              (tm->tm_min * 60) +
 229              tm->tm_sec);
 230 #endif
 231
 232         if (t == (time_t) -1) return 0;
 233
 234         return t;
 235 }
 236
 237
 238 time_t
 239 parse_date(unsigned char **date_pos, unsigned char *end,
 240            int update_pos, int skip_week_day)
 241 {
 242 #define skip_time_sep(date, end) \
 243         do { \
 244                 const unsigned char *start = (date); \
 245                 while ((!(end) || (date) < (end)) \
 246                         && (*(date) == ' ' || *(date) == '-')) \
 247                         (date)++; \
 248                 if (date == start) return 0; \
 249         } while (0)
 250
 251         struct tm tm;
 252         const unsigned char *date = (const unsigned char *) *date_pos;
 253
 254         if (!date) return 0;
 255
 256         if (skip_week_day) {
 257                 /* Skip day-of-week */
 258                 for (; (!end || date < end) && *date != ' '; date++)
 259                         if (!*date) return 0;
 260
 261                 /* As pasky said who cares if we allow '-'s here? */
 262                 skip_time_sep(date, end);
 263         }
 264
 265         if (isdigit(*date)) {
 266                 /* RFC 1036 / RFC 1123 */
 267
 268                 /* Eat day */
 269
 270                 /* date++; */
 271                 tm.tm_mday = parse_day(&date, end);
 272                 if (tm.tm_mday > 31) return 0;
 273
 274                 skip_time_sep(date, end);
 275
 276                 /* Eat month */
 277
 278                 tm.tm_mon = parse_month(&date, end);
 279                 if (tm.tm_mon < 0) return 0;
 280
 281                 skip_time_sep(date, end);
 282
 283                 /* Eat year */
 284
 285                 tm.tm_year = parse_year(&date, end);
 286                 if (tm.tm_year < 0) return 0;
 287
 288                 skip_time_sep(date, end);
 289
 290                 /* Eat time */
 291
 292                 if (!parse_time(&date, &tm, end)) return 0;
 293
 294         } else {
 295                 /* ANSI C's asctime() format */
 296
 297                 /* Eat month */
 298
 299                 tm.tm_mon = parse_month(&date, end);
 300                 if (tm.tm_mon < 0) return 0;
 301
 302                 /* I know, we shouldn't allow '-', but who cares ;). --pasky */
 303                 skip_time_sep(date, end);
 304
 305                 /* Eat day */
 306
 307                 tm.tm_mday = parse_day(&date, end);
 308                 if (tm.tm_mday > 31) return 0;
 309
 310                 skip_time_sep(date, end);
 311
 312                 /* Eat time */
 313
 314                 if (!parse_time(&date, &tm, end)) return 0;
 315
 316                 skip_time_sep(date, end);
 317
 318                 /* Eat year */
 319
 320                 tm.tm_year = parse_year(&date, end);
 321                 if (tm.tm_year < 0) return 0;
 322         }
 323 #undef skip_time_sep
 324
 325         if (update_pos)
 326                 *date_pos = (unsigned char *) date;
 327
 328         return (time_t) my_timegm(&tm);
 329 }