+++ /dev/null
-/* $Id: date.c 7136 2005-03-11 19:18:27Z rra $
-**
-** Date parsing and conversion routines.
-**
-** Provides various date parsing and conversion routines, including
-** generating Date headers for posted articles. Note that the parsedate
-** parser is separate from this file.
-*/
-
-#include "config.h"
-#include "clibrary.h"
-#include <ctype.h>
-#include <time.h>
-
-#include "libinn.h"
-
-/*
-** Time constants.
-**
-** Do not translate these names. RFC 822 by way of RFC 1036 requires that
-** weekday and month names *not* be translated. This is why we use static
-** tables rather than strftime for building dates, to avoid locale
-** interference.
-*/
-
-static const char WEEKDAY[7][4] = {
- "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
-};
-
-static const char MONTH[12][4] = {
- "Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct",
- "Nov", "Dec"
-};
-
-/* Number of days in a month. */
-static const int MONTHDAYS[] = {
- 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
-};
-
-/* Non-numeric time zones. Supporting these is required to support the
- obsolete date format of RFC 2822. The military time zones are handled
- separately. */
-static const struct {
- const char name[4];
- long offset;
-} ZONE_OFFSET[] = {
- { "UT", 0 }, { "GMT", 0 },
- { "EDT", -4 * 60 * 60 }, { "EST", -5 * 60 * 60 },
- { "CDT", -5 * 60 * 60 }, { "CST", -6 * 60 * 60 },
- { "MDT", -6 * 60 * 60 }, { "MST", -7 * 60 * 60 },
- { "PDT", -7 * 60 * 60 }, { "PST", -8 * 60 * 60 },
-};
-
-
-/*
-** Time parsing macros.
-*/
-
-/* Whether a given year is a leap year. */
-#define ISLEAP(year) \
- (((year) % 4) == 0 && (((year) % 100) != 0 || ((year) % 400) == 0))
-
-
-/*
-** RFC 2822 date parsing rules.
-*/
-
-/* The data structure to store a rule. The interpretation of the other fields
- is based on the value of type. For NUMBER, read between min and max
- characters and convert to a number. For LOOKUP, look for max characters
- and find that string in the provided table (with size elements). For
- DELIM, just make sure that we see the character stored in delimiter. */
-struct rule {
- enum {
- TYPE_NUMBER,
- TYPE_LOOKUP,
- TYPE_DELIM
- } type;
- char delimiter;
- const char (*table)[4];
- size_t size;
- int min;
- int max;
-};
-
-
-/*
-** Given a time as a time_t, return the offset in seconds of the local time
-** zone from UTC at that time (adding the offset to UTC time yields local
-** time). If the second argument is true, the time represents the current
-** time and in that circumstance we can assume that timezone/altzone are
-** correct. (We can't for arbitrary times in the past.)
-*/
-static long
-local_tz_offset(time_t date, bool current UNUSED)
-{
- struct tm *tm;
-#if !HAVE_TM_GMTOFF
- struct tm local, gmt;
- long offset;
-#endif
-
- tm = localtime(&date);
-
-#if !HAVE_TM_GMTOFF && HAVE_VAR_TIMEZONE
- if (current)
- return (tm->tm_isdst > 0) ? -altzone : -timezone;
-#endif
-
-#if HAVE_TM_GMTOFF
- return tm->tm_gmtoff;
-#else
- /* We don't have any easy returnable value, so we call both localtime
- and gmtime and calculate the difference. Assume that local time is
- never more than 24 hours away from UTC and ignore seconds. */
- local = *tm;
- tm = gmtime(&date);
- gmt = *tm;
- offset = local.tm_yday - gmt.tm_yday;
- if (offset < -1) {
- /* Local time is in the next year. */
- offset = 24;
- } else if (offset > 1) {
- /* Local time is in the previous year. */
- offset = -24;
- } else {
- offset *= 24;
- }
- offset += local.tm_hour - gmt.tm_hour;
- offset *= 60;
- offset += local.tm_min - gmt.tm_min;
- return offset * 60;
-#endif /* !HAVE_TM_GMTOFF */
-}
-
-
-/*
-** Given a time_t, a flag saying whether to use local time, a buffer, and
-** the length of the buffer, write the contents of a valid RFC 2822 / RFC
-** 1036 Date header into the buffer (provided it's long enough). Returns
-** true on success, false if the buffer is too long. Use snprintf rather
-** than strftime to be absolutely certain that locales don't result in the
-** wrong output. If the time is -1, obtain and use the current time.
-*/
-bool
-makedate(time_t date, bool local, char *buff, size_t buflen)
-{
- time_t realdate;
- struct tm *tmp_tm;
- struct tm tm;
- long tz_offset;
- int tz_hour_offset, tz_min_offset, tz_sign;
- size_t date_length;
- const char *tz_name;
-
- /* Make sure the buffer is large enough. A complete RFC 2822 date with
- spaces wherever FWS is required and the optional weekday takes:
-
- 1 2 3
- 1234567890123456789012345678901
- Sat, 31 Aug 2002 23:45:18 +0000
-
- 31 characters, plus another character for the trailing nul. The buffer
- will need to have another six characters of space to get the optional
- trailing time zone comment. */
- if (buflen < 32)
- return false;
-
- /* Get the current time if the provided time is -1. */
- realdate = (date == (time_t) -1) ? time(NULL) : date;
-
- /* RFC 2822 says the timezone offset is given as [+-]HHMM, so we have to
- separate the offset into a sign, hours, and minutes. Dividing the
- offset by 36 looks like it works, but will fail for any offset that
- isn't an even number of hours, and there are half-hour timezones. */
- if (local) {
- tmp_tm = localtime(&realdate);
- tm = *tmp_tm;
- tz_offset = local_tz_offset(realdate, date == (time_t) -1);
- tz_sign = (tz_offset < 0) ? -1 : 1;
- tz_offset *= tz_sign;
- tz_hour_offset = tz_offset / 3600;
- tz_min_offset = (tz_offset % 3600) / 60;
- } else {
- tmp_tm = gmtime(&realdate);
- tm = *tmp_tm;
- tz_sign = 1;
- tz_hour_offset = 0;
- tz_min_offset = 0;
- }
-
- /* tz_min_offset cannot be larger than 60 (by basic mathematics). If
- through some insane circumtances, tz_hour_offset would be larger,
- reject the time as invalid rather than generate an invalid date. */
- if (tz_hour_offset > 24)
- return false;
-
- /* Generate the actual date string, sans the trailing time zone comment
- but with the day of the week and the seconds (both of which are
- optional in the standard). */
- snprintf(buff, buflen, "%3.3s, %d %3.3s %d %02d:%02d:%02d %c%02d%02d",
- &WEEKDAY[tm.tm_wday][0], tm.tm_mday, &MONTH[tm.tm_mon][0],
- 1900 + tm.tm_year, tm.tm_hour, tm.tm_min, tm.tm_sec,
- (tz_sign > 0) ? '+' : '-', tz_hour_offset, tz_min_offset);
- date_length = strlen(buff);
-
- /* Now, get a pointer to the time zone abbreviation, and if there is
- enough room in the buffer, add it to the end of the date string as a
- comment. */
- if (!local) {
- tz_name = "UTC";
- } else {
-#if HAVE_TM_ZONE
- tz_name = tm.tm_zone;
-#elif HAVE_VAR_TZNAME
- tz_name = tzname[(tm.tm_isdst > 0) ? 1 : 0];
-#else
- tz_name = NULL;
-#endif
- }
- if (tz_name != NULL && date_length + 4 + strlen(tz_name) <= buflen) {
- snprintf(buff + date_length, buflen - date_length, " (%s)", tz_name);
- }
- return true;
-}
-
-
-/*
-** Given a struct tm representing a calendar time in UTC, convert it to
-** seconds since epoch. Returns (time_t) -1 if the time is not
-** convertable. Note that this function does not canonicalize the provided
-** struct tm, nor does it allow out of range values or years before 1970.
-*/
-static time_t
-mktime_utc(const struct tm *tm)
-{
- time_t result = 0;
- int i;
-
- /* We do allow some ill-formed dates, but we don't do anything special
- with them and our callers really shouldn't pass them to us. Do
- explicitly disallow the ones that would cause invalid array accesses
- or other algorithm problems. */
- if (tm->tm_mon < 0 || tm->tm_mon > 11 || tm->tm_year < 70)
- return (time_t) -1;
-
- /* Convert to a time_t. */
- for (i = 1970; i < tm->tm_year + 1900; i++)
- result += 365 + ISLEAP(i);
- for (i = 0; i < tm->tm_mon; i++)
- result += MONTHDAYS[i];
- if (tm->tm_mon > 1 && ISLEAP(tm->tm_year + 1900))
- result++;
- result = 24 * (result + tm->tm_mday - 1) + tm->tm_hour;
- result = 60 * result + tm->tm_min;
- result = 60 * result + tm->tm_sec;
- return result;
-}
-
-
-/*
-** Check the ranges of values in a struct tm to make sure that the date was
-** well-formed. Assumes that the year has already been correctly set to
-** something (but may be before 1970).
-*/
-static bool
-valid_tm(const struct tm *tm)
-{
- if (tm->tm_sec > 60 || tm->tm_min > 59 || tm->tm_hour > 23)
- return false;
- if (tm->tm_mday < 1 || tm->tm_mon < 0 || tm->tm_mon > 11)
- return false;
-
- /* Make sure that the day isn't past the end of the month, allowing for
- leap years. */
- if (tm->tm_mday > MONTHDAYS[tm->tm_mon]
- && (tm->tm_mon != 1 || tm->tm_mday > 29
- || !ISLEAP(tm->tm_year + 1900)))
- return false;
-
- /* We can't handle years before 1970. */
- if (tm->tm_year < 70)
- return false;
-
- return true;
-}
-
-
-/*
-** Parse a date in the format used in NNTP commands such as NEWGROUPS and
-** NEWNEWS. The first argument is a string of the form YYYYMMDD and the
-** second a string of the form HHMMSS. The third argument is a boolean
-** flag saying whether the date is specified in local time; if false, the
-** date is assumed to be in UTC. Returns the time_t corresponding to the
-** given date and time or (time_t) -1 in the event of an error.
-*/
-time_t
-parsedate_nntp(const char *date, const char *hour, bool local)
-{
- const char *p;
- size_t datelen;
- time_t now, result;
- struct tm tm;
- struct tm *current;
- int century;
-
- /* Accept YYMMDD and YYYYMMDD. The first is what RFC 977 requires. The
- second is what the revision of RFC 977 will require. */
- datelen = strlen(date);
- if ((datelen != 6 && datelen != 8) || strlen(hour) != 6)
- return (time_t) -1;
- for (p = date; *p; p++)
- if (!CTYPE(isdigit, *p))
- return (time_t) -1;
- for (p = hour; *p; p++)
- if (!CTYPE(isdigit, *p))
- return (time_t) -1;
-
- /* Parse the date into a struct tm, skipping over the century part of
- the year, if any. We'll deal with it in a moment. */
- tm.tm_isdst = -1;
- p = date + datelen - 6;
- tm.tm_year = (p[0] - '0') * 10 + p[1] - '0';
- tm.tm_mon = (p[2] - '0') * 10 + p[3] - '0' - 1;
- tm.tm_mday = (p[4] - '0') * 10 + p[5] - '0';
- p = hour;
- tm.tm_hour = (p[0] - '0') * 10 + p[1] - '0';
- tm.tm_min = (p[2] - '0') * 10 + p[3] - '0';
- tm.tm_sec = (p[4] - '0') * 10 + p[5] - '0';
-
- /* Four-digit years are the easy case.
-
- For two-digit years, RFC 977 says "The closest century is assumed as
- part of the year (i.e., 86 specifies 1986, 30 specifies 2030, 99 is
- 1999, 00 is 2000)." draft-ietf-nntpext-base-10.txt simplifies this
- considerably and is what we implement:
-
- If the first two digits of the year are not specified, the year is
- to be taken from the current century if YY is smaller than or equal
- to the current year, otherwise the year is from the previous
- century.
-
- This implementation assumes "current year" means the last two digits
- of the current year. Note that this algorithm interacts poorly with
- clients with a slightly fast clock around the turn of a century, as
- it may send 00 for the year when the year on the server is still xx99
- and have it taken to be 99 years in the past. But 2000 has come and
- gone, and by 2100 news clients *really* should have started using UTC
- for everything like the new draft recommends. */
- if (datelen == 8) {
- tm.tm_year += (date[0] - '0') * 1000 + (date[1] - '0') * 100;
- tm.tm_year -= 1900;
- } else {
- now = time(NULL);
- current = local ? localtime(&now) : gmtime(&now);
- century = current->tm_year / 100;
- if (tm.tm_year > current->tm_year % 100)
- century--;
- tm.tm_year += century * 100;
- }
-
- /* Ensure that all of the date components are within valid ranges. */
- if (!valid_tm(&tm))
- return (time_t) -1;
-
- /* tm contains the broken-down date; convert it to a time_t. mktime
- assumes the supplied struct tm is in the local time zone; if given a
- time in UTC, use our own routine instead. */
- result = local ? mktime(&tm) : mktime_utc(&tm);
- return result;
-}
-
-
-/*
-** Skip any amount of CFWS (comments and folding whitespace), the RFC 2822
-** grammar term for whitespace, CRLF pairs, and possibly nested comments that
-** may contain escaped parens. We also allow simple newlines since we don't
-** always deal with wire-format messages. Note that we do not attempt to
-** ensure that CRLF or a newline is followed by whitespace. Returns the new
-** position of the pointer.
-*/
-static const char *
-skip_cfws(const char *p)
-{
- int nesting = 0;
-
- for (; *p != '\0'; p++) {
- switch (*p) {
- case ' ':
- case '\t':
- case '\n':
- break;
- case '\r':
- if (p[1] != '\n')
- return p;
- p++;
- break;
- case '(':
- nesting++;
- break;
- case ')':
- if (nesting == 0)
- return p;
- nesting--;
- break;
- case '\\':
- if (nesting == 0 || p[1] == '\0')
- return p;
- p++;
- break;
- default:
- if (nesting == 0)
- return p;
- break;
- }
- }
- return p;
-}
-
-
-/*
-** Parse a single number. Takes the parsing rule that we're applying and
-** returns a pointer to the new position of the parse stream. If there
-** aren't enough digits, return NULL.
-*/
-static const char *
-parse_number(const char *p, const struct rule *rule, int *value)
-{
- int count;
-
- *value = 0;
- for (count = 0; *p != '\0' && count < rule->max; p++, count++) {
- if (*p < '0' || *p > '9')
- break;
- *value = *value * 10 + (*p - '0');
- }
- if (count < rule->min || count > rule->max)
- return NULL;
- return p;
-}
-
-
-/*
-** Parse a single string value that has to be done via table lookup. Takes
-** the parsing rule that we're applying. Puts the index number of the string
-** if found into the value pointerand returns the new position of the string,
-** or NULL if the string could not be found in the table.
-*/
-static const char *
-parse_lookup(const char *p, const struct rule *rule, int *value)
-{
- size_t i;
-
- for (i = 0; i < rule->size; i++)
- if (strncasecmp(rule->table[i], p, rule->max) == 0) {
- p += rule->max;
- *value = i;
- return p;
- }
- return NULL;
-}
-
-
-/*
-** Apply a set of date parsing rules to a string. Returns the new position
-** in the parse string if this succeeds and NULL if it fails. As part of the
-** parse, stores values into the value pointer in the array of rules that was
-** passed in. Takes an array of rules and a count of rules in that array.
-*/
-static const char *
-parse_by_rule(const char *p, const struct rule rules[], size_t count,
- int *values)
-{
- size_t i;
- const struct rule *rule;
-
- for (i = 0; i < count; i++) {
- rule = &rules[i];
-
- switch (rule->type) {
- case TYPE_DELIM:
- if (*p != rule->delimiter)
- return NULL;
- p++;
- break;
- case TYPE_LOOKUP:
- p = parse_lookup(p, rule, &values[i]);
- if (p == NULL)
- return NULL;
- break;
- case TYPE_NUMBER:
- p = parse_number(p, rule, &values[i]);
- if (p == NULL)
- return NULL;
- break;
- }
-
- p = skip_cfws(p);
- }
- return p;
-}
-
-
-/*
-** Parse a legacy time zone. This uses the parsing rules in RFC 2822,
-** including assigning an offset of 0 to all single-character military time
-** zones due to their ambiguity in practice. Returns the new position in the
-** parse stream or NULL if we failed to parse the zone.
-*/
-static const char *
-parse_legacy_timezone(const char *p, long *offset)
-{
- const char *end;
- size_t max, i;
-
- for (end = p; *end != '\0' && !CTYPE(isspace, *end); end++)
- ;
- if (end == p)
- return NULL;
- max = end - p;
- for (i = 0; i < ARRAY_SIZE(ZONE_OFFSET); i++)
- if (strncasecmp(ZONE_OFFSET[i].name, p, max) == 0) {
- p += strlen(ZONE_OFFSET[i].name);
- *offset = ZONE_OFFSET[i].offset;
- return p;
- }
- if (max == 1 && CTYPE(isalpha, *p) && *p != 'J' && *p != 'j') {
- *offset = 0;
- return p + 1;
- }
- return NULL;
-}
-
-
-/*
-** Parse an RFC 2822 date, accepting the normal and obsolete syntax. Takes a
-** pointer to the beginning of the date and the length. Returns the
-** translated time in seconds since epoch, or (time_t) -1 on error.
-*/
-time_t
-parsedate_rfc2822(const char *date)
-{
- const char *p;
- int zone_sign;
- long zone_offset;
- struct tm tm;
- int values[8];
- time_t result;
-
- /* The basic rules. Note that we don't bother to check whether the day of
- the week is accurate or not. */
- static const struct rule base_rule[] = {
- { TYPE_LOOKUP, 0, WEEKDAY, 7, 3, 3 },
- { TYPE_DELIM, ',', NULL, 0, 1, 1 },
- { TYPE_NUMBER, 0, NULL, 0, 1, 2 },
- { TYPE_LOOKUP, 0, MONTH, 12, 3, 3 },
- { TYPE_NUMBER, 0, NULL, 0, 2, 4 },
- { TYPE_NUMBER, 0, NULL, 0, 2, 2 },
- { TYPE_DELIM, ':', NULL, 0, 1, 1 },
- { TYPE_NUMBER, 0, NULL, 0, 2, 2 }
- };
-
- /* Optional seconds at the end of the time. */
- static const struct rule seconds_rule[] = {
- { TYPE_DELIM, ':', NULL, 0, 1, 1 },
- { TYPE_NUMBER, 0, NULL, 0, 2, 2 }
- };
-
- /* Numeric time zone. */
- static const struct rule zone_rule[] = {
- { TYPE_NUMBER, 0, NULL, 0, 4, 4 }
- };
-
- /* Start with a clean slate. */
- memset(&tm, 0, sizeof(struct tm));
- memset(values, 0, sizeof(values));
-
- /* Parse the base part of the date. The initial day of the week is
- optional. */
- p = skip_cfws(date);
- if (CTYPE(isalpha, *p))
- p = parse_by_rule(p, base_rule, ARRAY_SIZE(base_rule), values);
- else
- p = parse_by_rule(p, base_rule + 2, ARRAY_SIZE(base_rule) - 2,
- values + 2);
- if (p == NULL)
- return (time_t) -1;
-
- /* Stash the results into a struct tm. Values are associated with the
- rule number of the same index. */
- tm.tm_mday = values[2];
- tm.tm_mon = values[3];
- tm.tm_year = values[4];
- tm.tm_hour = values[5];
- tm.tm_min = values[7];
-
- /* Parse seconds if they're present. */
- if (*p == ':') {
- p = parse_by_rule(p, seconds_rule, ARRAY_SIZE(seconds_rule), values);
- if (p == NULL)
- return (time_t) -1;
- tm.tm_sec = values[1];
- }
-
- /* Time zone. Unfortunately this is weird enough that we can't use nice
- parsing rules for it. */
- if (*p == '-' || *p == '+') {
- zone_sign = (*p == '+') ? 1 : -1;
- p = parse_by_rule(p + 1, zone_rule, ARRAY_SIZE(zone_rule), values);
- if (p == NULL)
- return (time_t) -1;
- zone_offset = ((values[0] / 100) * 60 + values[0] % 100) * 60;
- zone_offset *= zone_sign;
- } else {
- p = parse_legacy_timezone(p, &zone_offset);
- if (p == NULL)
- return (time_t) -1;
- }
-
- /* Fix up the year, using the RFC 2822 rules. Remember that tm_year
- stores the year - 1900. */
- if (tm.tm_year < 50)
- tm.tm_year += 100;
- else if (tm.tm_year >= 1000)
- tm.tm_year -= 1900;
-
- /* Done parsing. Make sure there's nothing left but CFWS and range-check
- our results and then convert the struct tm to seconds since epoch and
- then apply the time zone offset. */
- p = skip_cfws(p);
- if (*p != '\0')
- return (time_t) -1;
- if (!valid_tm(&tm))
- return (time_t) -1;
- result = mktime_utc(&tm);
- return (result == (time_t) -1) ? result : result - zone_offset;
-}
~ian / innduct.git / blobdiff