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/*
* Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License").
* You may not use this file except in compliance with the License.
* A copy of the License is located at
*
* http://aws.amazon.com/apache2.0
*
* or in the "license" file accompanying this file. This file is distributed
* on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
* express or implied. See the License for the specific language governing
* permissions and limitations under the License.
*/
#include "utils/s2n_asn1_time.h"
#include <ctype.h>
#include <time.h>
#include "utils/s2n_result.h"
#include "utils/s2n_safety.h"
typedef enum parser_state {
ON_YEAR_DIGIT_1 = 0,
ON_YEAR_DIGIT_2,
ON_YEAR_DIGIT_3,
ON_YEAR_DIGIT_4,
ON_MONTH_DIGIT_1,
ON_MONTH_DIGIT_2,
ON_DAY_DIGIT_1,
ON_DAY_DIGIT_2,
ON_HOUR_DIGIT_1,
ON_HOUR_DIGIT_2,
ON_MINUTE_DIGIT_1,
ON_MINUTE_DIGIT_2,
ON_SECOND_DIGIT_1,
ON_SECOND_DIGIT_2,
ON_SUBSECOND,
ON_TIMEZONE,
ON_OFFSET_HOURS_DIGIT_1,
ON_OFFSET_HOURS_DIGIT_2,
ON_OFFSET_MINUTES_DIGIT_1,
ON_OFFSET_MINUTES_DIGIT_2,
FINISHED,
PARSE_ERROR
} parser_state;
static inline long get_gmt_offset(struct tm *t)
{
/* See: https://sourceware.org/git/?p=glibc.git;a=blob;f=include/features.h;h=ba272078cf2263ec88e039fda7524c136a4a7953;hb=HEAD */
#if defined(__USE_MISC) || defined(__FreeBSD__) || defined(__NetBSD__) || defined(__ANDROID__) \
|| defined(ANDROID) || defined(__APPLE__) && defined(__MACH__)
return t->tm_gmtoff;
#else
return t->tm_gmtoff;
#endif
}
static inline void get_current_timesettings(long *gmt_offset, int *is_dst)
{
struct tm time_ptr = { 0 };
time_t raw_time;
time(&raw_time);
localtime_r(&raw_time, &time_ptr);
*gmt_offset = get_gmt_offset(&time_ptr);
*is_dst = time_ptr.tm_isdst;
}
#define PARSE_DIGIT(c, d) \
do { \
RESULT_ENSURE(isdigit(c), S2N_ERR_SAFETY); \
d = c - '0'; \
} while (0)
/* this is just a standard state machine for ASN1 date format... nothing special.
* just do a character at a time and change the state per character encountered.
* when finished the above time structure should be filled in along with some
* crazy timezone info we'll need shortly afterwards.*/
static S2N_RESULT process_state(parser_state *state, char current_char, struct parser_args *args)
{
switch (*state) {
case ON_YEAR_DIGIT_1:
PARSE_DIGIT(current_char, args->current_digit);
args->time.tm_year = args->current_digit;
*state = ON_YEAR_DIGIT_2;
return S2N_RESULT_OK;
case ON_YEAR_DIGIT_2:
PARSE_DIGIT(current_char, args->current_digit);
args->time.tm_year = args->time.tm_year * 10 + args->current_digit;
*state = ON_YEAR_DIGIT_3;
return S2N_RESULT_OK;
case ON_YEAR_DIGIT_3:
PARSE_DIGIT(current_char, args->current_digit);
args->time.tm_year = args->time.tm_year * 10 + args->current_digit;
*state = ON_YEAR_DIGIT_4;
return S2N_RESULT_OK;
case ON_YEAR_DIGIT_4:
PARSE_DIGIT(current_char, args->current_digit);
args->time.tm_year = args->time.tm_year * 10 + args->current_digit;
args->time.tm_year -= 1900;
if (args->time.tm_year < 0) {
return S2N_RESULT_ERROR;
}
*state = ON_MONTH_DIGIT_1;
return S2N_RESULT_OK;
case ON_MONTH_DIGIT_1:
PARSE_DIGIT(current_char, args->current_digit);
args->time.tm_mon = args->current_digit;
*state = ON_MONTH_DIGIT_2;
return S2N_RESULT_OK;
case ON_MONTH_DIGIT_2:
PARSE_DIGIT(current_char, args->current_digit);
args->time.tm_mon = args->time.tm_mon * 10 + args->current_digit;
args->time.tm_mon -= 1;
if (args->time.tm_mon < 0 || args->time.tm_mon > 11) {
return S2N_RESULT_ERROR;
}
*state = ON_DAY_DIGIT_1;
return S2N_RESULT_OK;
case ON_DAY_DIGIT_1:
PARSE_DIGIT(current_char, args->current_digit);
args->time.tm_mday = args->current_digit;
*state = ON_DAY_DIGIT_2;
return S2N_RESULT_OK;
case ON_DAY_DIGIT_2:
PARSE_DIGIT(current_char, args->current_digit);
args->time.tm_mday = args->time.tm_mday * 10 + args->current_digit;
if (args->time.tm_mday < 0 || args->time.tm_mday > 31) {
return S2N_RESULT_ERROR;
}
*state = ON_HOUR_DIGIT_1;
return S2N_RESULT_OK;
case ON_HOUR_DIGIT_1:
PARSE_DIGIT(current_char, args->current_digit);
args->time.tm_hour = args->current_digit;
*state = ON_HOUR_DIGIT_2;
return S2N_RESULT_OK;
case ON_HOUR_DIGIT_2:
PARSE_DIGIT(current_char, args->current_digit);
args->time.tm_hour = args->time.tm_hour * 10 + args->current_digit;
if (args->time.tm_hour < 0 || args->time.tm_hour > 23) {
return S2N_RESULT_ERROR;
}
*state = ON_MINUTE_DIGIT_1;
return S2N_RESULT_OK;
case ON_MINUTE_DIGIT_1:
PARSE_DIGIT(current_char, args->current_digit);
args->time.tm_min = args->current_digit;
*state = ON_MINUTE_DIGIT_2;
return S2N_RESULT_OK;
case ON_MINUTE_DIGIT_2:
PARSE_DIGIT(current_char, args->current_digit);
args->time.tm_min = args->time.tm_min * 10 + args->current_digit;
if (args->time.tm_min < 0 || args->time.tm_min > 59) {
return S2N_RESULT_ERROR;
}
*state = ON_SECOND_DIGIT_1;
return S2N_RESULT_OK;
case ON_SECOND_DIGIT_1:
PARSE_DIGIT(current_char, args->current_digit);
args->time.tm_sec = args->current_digit;
*state = ON_SECOND_DIGIT_2;
return S2N_RESULT_OK;
case ON_SECOND_DIGIT_2:
PARSE_DIGIT(current_char, args->current_digit);
args->time.tm_sec = args->time.tm_sec * 10 + args->current_digit;
if (args->time.tm_sec < 0 || args->time.tm_sec > 59) {
return S2N_RESULT_ERROR;
}
*state = ON_SUBSECOND;
return S2N_RESULT_OK;
case ON_SUBSECOND:
if (current_char == '.' || isdigit(current_char)) {
*state = ON_SUBSECOND;
return S2N_RESULT_OK;
}
FALL_THROUGH;
case ON_TIMEZONE:
if (current_char == 'Z' || current_char == 'z') {
args->local_time_assumed = 0;
*state = FINISHED;
return S2N_RESULT_OK;
} else if (current_char == '-') {
args->local_time_assumed = 0;
args->offset_negative = 1;
*state = ON_OFFSET_HOURS_DIGIT_1;
return S2N_RESULT_OK;
} else if (current_char == '+') {
args->local_time_assumed = 0;
args->offset_negative = 0;
*state = ON_OFFSET_HOURS_DIGIT_1;
return S2N_RESULT_OK;
}
return S2N_RESULT_ERROR;
case ON_OFFSET_HOURS_DIGIT_1:
PARSE_DIGIT(current_char, args->current_digit);
args->offset_hours = args->current_digit;
*state = ON_OFFSET_HOURS_DIGIT_2;
return S2N_RESULT_OK;
case ON_OFFSET_HOURS_DIGIT_2:
PARSE_DIGIT(current_char, args->current_digit);
args->offset_hours = args->offset_hours * 10 + args->current_digit;
if (args->offset_hours < 0 || args->offset_hours > 23) {
return S2N_RESULT_ERROR;
}
*state = ON_OFFSET_MINUTES_DIGIT_1;
return S2N_RESULT_OK;
case ON_OFFSET_MINUTES_DIGIT_1:
PARSE_DIGIT(current_char, args->current_digit);
args->offset_minutes = args->current_digit;
*state = ON_OFFSET_MINUTES_DIGIT_2;
return S2N_RESULT_OK;
case ON_OFFSET_MINUTES_DIGIT_2:
PARSE_DIGIT(current_char, args->current_digit);
args->offset_minutes = args->offset_minutes * 10 + args->current_digit;
if (args->offset_minutes < 0 || args->offset_minutes > 23) {
return S2N_RESULT_ERROR;
}
*state = FINISHED;
return S2N_RESULT_OK;
default:
return S2N_RESULT_ERROR;
}
}
S2N_RESULT s2n_asn1_time_to_nano_since_epoch_ticks(const char *asn1_time, uint32_t len, uint64_t *ticks)
{
/* figure out if we are on something other than UTC since timegm is not supported everywhere. */
long gmt_offset_current = 0;
int is_dst = 0;
get_current_timesettings(&gmt_offset_current, &is_dst);
uint32_t str_len = len;
parser_state state = ON_YEAR_DIGIT_1;
struct parser_args args = {
.time = {
.tm_hour = 0,
.tm_isdst = -1,
.tm_mday = 0,
.tm_min = 0,
.tm_mon = 0,
.tm_sec = 0,
.tm_wday = 0,
.tm_yday = 0,
.tm_year = 0,
},
.current_digit = 0,
.local_time_assumed = 1,
.offset_hours = 0,
.offset_minutes = 0,
.offset_negative = 0
};
size_t current_pos = 0;
while (state < FINISHED && current_pos < str_len) {
char current_char = asn1_time[current_pos];
RESULT_ENSURE_OK(process_state(&state, current_char, &args), S2N_ERR_INVALID_ARGUMENT);
current_pos++;
}
/* state on subsecond means no timezone info was found and we assume local time */
RESULT_ENSURE(state == FINISHED || state == ON_SUBSECOND, S2N_ERR_INVALID_ARGUMENT);
time_t clock_data = mktime(&args.time);
RESULT_ENSURE_GTE(clock_data, 0);
/* ASN1 + and - is in format HHMM. We need to convert it to seconds for the adjustment */
long gmt_offset = (args.offset_hours * 3600) + (args.offset_minutes * 60);
if (args.offset_negative) {
gmt_offset = 0 - gmt_offset;
}
/* if we detected UTC is being used (please always use UTC), we need to add the detected timezone on the local
* machine back to the offset. Also, the offset includes an offset for daylight savings time. When the time being parsed
* and the local time are on different sides of the dst barrier, the offset has to be adjusted to account for it. */
if (!args.local_time_assumed) {
gmt_offset -= gmt_offset_current;
gmt_offset -= args.time.tm_isdst != is_dst ? (args.time.tm_isdst - is_dst) * 3600 : 0;
}
RESULT_ENSURE_GTE(clock_data, gmt_offset);
/* convert to nanoseconds and add the timezone offset. */
*ticks = ((uint64_t) clock_data - gmt_offset) * 1000000000;
return S2N_RESULT_OK;
}
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