1use std::cmp;
2use std::fmt::{self, Display, Formatter};
3use std::str::FromStr;
4use std::time::{Duration, SystemTime, UNIX_EPOCH};
5
6use crate::Error;
7
8/// HTTP timestamp type.
9///
10/// Parse using `FromStr` impl.
11/// Format using the `Display` trait.
12/// Convert timestamp into/from `SytemTime` to use.
13/// Supports comparsion and sorting.
14#[derive(Copy, Clone, Debug, Eq, PartialEq, Hash)]
15pub struct HttpDate {
16 /// 0...59
17 sec: u8,
18 /// 0...59
19 min: u8,
20 /// 0...23
21 hour: u8,
22 /// 1...31
23 day: u8,
24 /// 1...12
25 mon: u8,
26 /// 1970...9999
27 year: u16,
28 /// 1...7
29 wday: u8,
30}
31
32impl HttpDate {
33 fn is_valid(&self) -> bool {
34 self.sec < 60
35 && self.min < 60
36 && self.hour < 24
37 && self.day > 0
38 && self.day < 32
39 && self.mon > 0
40 && self.mon <= 12
41 && self.year >= 1970
42 && self.year <= 9999
43 && &HttpDate::from(SystemTime::from(*self)) == self
44 }
45}
46
47impl From<SystemTime> for HttpDate {
48 fn from(v: SystemTime) -> HttpDate {
49 let dur = v
50 .duration_since(UNIX_EPOCH)
51 .expect("all times should be after the epoch");
52 let secs_since_epoch = dur.as_secs();
53
54 if secs_since_epoch >= 253402300800 {
55 // year 9999
56 panic!("date must be before year 9999");
57 }
58
59 /* 2000-03-01 (mod 400 year, immediately after feb29 */
60 const LEAPOCH: i64 = 11017;
61 const DAYS_PER_400Y: i64 = 365 * 400 + 97;
62 const DAYS_PER_100Y: i64 = 365 * 100 + 24;
63 const DAYS_PER_4Y: i64 = 365 * 4 + 1;
64
65 let days = (secs_since_epoch / 86400) as i64 - LEAPOCH;
66 let secs_of_day = secs_since_epoch % 86400;
67
68 let mut qc_cycles = days / DAYS_PER_400Y;
69 let mut remdays = days % DAYS_PER_400Y;
70
71 if remdays < 0 {
72 remdays += DAYS_PER_400Y;
73 qc_cycles -= 1;
74 }
75
76 let mut c_cycles = remdays / DAYS_PER_100Y;
77 if c_cycles == 4 {
78 c_cycles -= 1;
79 }
80 remdays -= c_cycles * DAYS_PER_100Y;
81
82 let mut q_cycles = remdays / DAYS_PER_4Y;
83 if q_cycles == 25 {
84 q_cycles -= 1;
85 }
86 remdays -= q_cycles * DAYS_PER_4Y;
87
88 let mut remyears = remdays / 365;
89 if remyears == 4 {
90 remyears -= 1;
91 }
92 remdays -= remyears * 365;
93
94 let mut year = 2000 + remyears + 4 * q_cycles + 100 * c_cycles + 400 * qc_cycles;
95
96 let months = [31, 30, 31, 30, 31, 31, 30, 31, 30, 31, 31, 29];
97 let mut mon = 0;
98 for mon_len in months.iter() {
99 mon += 1;
100 if remdays < *mon_len {
101 break;
102 }
103 remdays -= *mon_len;
104 }
105 let mday = remdays + 1;
106 let mon = if mon + 2 > 12 {
107 year += 1;
108 mon - 10
109 } else {
110 mon + 2
111 };
112
113 let mut wday = (3 + days) % 7;
114 if wday <= 0 {
115 wday += 7
116 };
117
118 HttpDate {
119 sec: (secs_of_day % 60) as u8,
120 min: ((secs_of_day % 3600) / 60) as u8,
121 hour: (secs_of_day / 3600) as u8,
122 day: mday as u8,
123 mon: mon as u8,
124 year: year as u16,
125 wday: wday as u8,
126 }
127 }
128}
129
130impl From<HttpDate> for SystemTime {
131 fn from(v: HttpDate) -> SystemTime {
132 let leap_years =
133 ((v.year - 1) - 1968) / 4 - ((v.year - 1) - 1900) / 100 + ((v.year - 1) - 1600) / 400;
134 let mut ydays = match v.mon {
135 1 => 0,
136 2 => 31,
137 3 => 59,
138 4 => 90,
139 5 => 120,
140 6 => 151,
141 7 => 181,
142 8 => 212,
143 9 => 243,
144 10 => 273,
145 11 => 304,
146 12 => 334,
147 _ => unreachable!(),
148 } + v.day as u64
149 - 1;
150 if is_leap_year(v.year) && v.mon > 2 {
151 ydays += 1;
152 }
153 let days = (v.year as u64 - 1970) * 365 + leap_years as u64 + ydays;
154 UNIX_EPOCH
155 + Duration::from_secs(
156 v.sec as u64 + v.min as u64 * 60 + v.hour as u64 * 3600 + days * 86400,
157 )
158 }
159}
160
161impl FromStr for HttpDate {
162 type Err = Error;
163
164 fn from_str(s: &str) -> Result<HttpDate, Error> {
165 if !s.is_ascii() {
166 return Err(Error(()));
167 }
168 let x: &[u8] = s.trim().as_bytes();
169 let date: HttpDate = parse_imf_fixdate(x)
170 .or_else(|_| parse_rfc850_date(x))
171 .or_else(|_| parse_asctime(x))?;
172 if !date.is_valid() {
173 return Err(Error(()));
174 }
175 Ok(date)
176 }
177}
178
179impl Display for HttpDate {
180 fn fmt(&self, f: &mut Formatter) -> fmt::Result {
181 let wday = match self.wday {
182 1 => b"Mon",
183 2 => b"Tue",
184 3 => b"Wed",
185 4 => b"Thu",
186 5 => b"Fri",
187 6 => b"Sat",
188 7 => b"Sun",
189 _ => unreachable!(),
190 };
191
192 let mon = match self.mon {
193 1 => b"Jan",
194 2 => b"Feb",
195 3 => b"Mar",
196 4 => b"Apr",
197 5 => b"May",
198 6 => b"Jun",
199 7 => b"Jul",
200 8 => b"Aug",
201 9 => b"Sep",
202 10 => b"Oct",
203 11 => b"Nov",
204 12 => b"Dec",
205 _ => unreachable!(),
206 };
207
208 let mut buf: [u8; 29] = *b" , 00 0000 00:00:00 GMT";
209 buf[0] = wday[0];
210 buf[1] = wday[1];
211 buf[2] = wday[2];
212 buf[5] = b'0' + (self.day / 10) as u8;
213 buf[6] = b'0' + (self.day % 10) as u8;
214 buf[8] = mon[0];
215 buf[9] = mon[1];
216 buf[10] = mon[2];
217 buf[12] = b'0' + (self.year / 1000) as u8;
218 buf[13] = b'0' + (self.year / 100 % 10) as u8;
219 buf[14] = b'0' + (self.year / 10 % 10) as u8;
220 buf[15] = b'0' + (self.year % 10) as u8;
221 buf[17] = b'0' + (self.hour / 10) as u8;
222 buf[18] = b'0' + (self.hour % 10) as u8;
223 buf[20] = b'0' + (self.min / 10) as u8;
224 buf[21] = b'0' + (self.min % 10) as u8;
225 buf[23] = b'0' + (self.sec / 10) as u8;
226 buf[24] = b'0' + (self.sec % 10) as u8;
227 f.write_str(std::str::from_utf8(&buf[..]).unwrap())
228 }
229}
230
231impl Ord for HttpDate {
232 fn cmp(&self, other: &HttpDate) -> cmp::Ordering {
233 SystemTime::from(*self).cmp(&SystemTime::from(*other))
234 }
235}
236
237impl PartialOrd for HttpDate {
238 fn partial_cmp(&self, other: &HttpDate) -> Option<cmp::Ordering> {
239 Some(self.cmp(other))
240 }
241}
242
243fn toint_1(x: u8) -> Result<u8, Error> {
244 let result: u8 = x.wrapping_sub(b'0');
245 if result < 10 {
246 Ok(result)
247 } else {
248 Err(Error(()))
249 }
250}
251
252fn toint_2(s: &[u8]) -> Result<u8, Error> {
253 let high: u8 = s[0].wrapping_sub(b'0');
254 let low: u8 = s[1].wrapping_sub(b'0');
255
256 if high < 10 && low < 10 {
257 Ok(high * 10 + low)
258 } else {
259 Err(Error(()))
260 }
261}
262
263#[allow(clippy::many_single_char_names)]
264fn toint_4(s: &[u8]) -> Result<u16, Error> {
265 let a: u16 = u16::from(s[0].wrapping_sub(b'0'));
266 let b: u16 = u16::from(s[1].wrapping_sub(b'0'));
267 let c: u16 = u16::from(s[2].wrapping_sub(b'0'));
268 let d: u16 = u16::from(s[3].wrapping_sub(b'0'));
269
270 if a < 10 && b < 10 && c < 10 && d < 10 {
271 Ok(a * 1000 + b * 100 + c * 10 + d)
272 } else {
273 Err(Error(()))
274 }
275}
276
277fn parse_imf_fixdate(s: &[u8]) -> Result<HttpDate, Error> {
278 // Example: `Sun, 06 Nov 1994 08:49:37 GMT`
279 if s.len() != 29 || &s[25..] != b" GMT" || s[16] != b' ' || s[19] != b':' || s[22] != b':' {
280 return Err(Error(()));
281 }
282 Ok(HttpDate {
283 sec: toint_2(&s[23..25])?,
284 min: toint_2(&s[20..22])?,
285 hour: toint_2(&s[17..19])?,
286 day: toint_2(&s[5..7])?,
287 mon: match &s[7..12] {
288 b" Jan " => 1,
289 b" Feb " => 2,
290 b" Mar " => 3,
291 b" Apr " => 4,
292 b" May " => 5,
293 b" Jun " => 6,
294 b" Jul " => 7,
295 b" Aug " => 8,
296 b" Sep " => 9,
297 b" Oct " => 10,
298 b" Nov " => 11,
299 b" Dec " => 12,
300 _ => return Err(Error(())),
301 },
302 year: toint_4(&s[12..16])?,
303 wday: match &s[..5] {
304 b"Mon, " => 1,
305 b"Tue, " => 2,
306 b"Wed, " => 3,
307 b"Thu, " => 4,
308 b"Fri, " => 5,
309 b"Sat, " => 6,
310 b"Sun, " => 7,
311 _ => return Err(Error(())),
312 },
313 })
314}
315
316fn parse_rfc850_date(s: &[u8]) -> Result<HttpDate, Error> {
317 // Example: `Sunday, 06-Nov-94 08:49:37 GMT`
318 if s.len() < 23 {
319 return Err(Error(()));
320 }
321
322 fn wday<'a>(s: &'a [u8], wday: u8, name: &'static [u8]) -> Option<(u8, &'a [u8])> {
323 if &s[0..name.len()] == name {
324 return Some((wday, &s[name.len()..]));
325 }
326 None
327 }
328 let (wday, s) = wday(s, 1, b"Monday, ")
329 .or_else(|| wday(s, 2, b"Tuesday, "))
330 .or_else(|| wday(s, 3, b"Wednesday, "))
331 .or_else(|| wday(s, 4, b"Thursday, "))
332 .or_else(|| wday(s, 5, b"Friday, "))
333 .or_else(|| wday(s, 6, b"Saturday, "))
334 .or_else(|| wday(s, 7, b"Sunday, "))
335 .ok_or(Error(()))?;
336 if s.len() != 22 || s[12] != b':' || s[15] != b':' || &s[18..22] != b" GMT" {
337 return Err(Error(()));
338 }
339 let mut year = u16::from(toint_2(&s[7..9])?);
340 if year < 70 {
341 year += 2000;
342 } else {
343 year += 1900;
344 }
345 Ok(HttpDate {
346 sec: toint_2(&s[16..18])?,
347 min: toint_2(&s[13..15])?,
348 hour: toint_2(&s[10..12])?,
349 day: toint_2(&s[0..2])?,
350 mon: match &s[2..7] {
351 b"-Jan-" => 1,
352 b"-Feb-" => 2,
353 b"-Mar-" => 3,
354 b"-Apr-" => 4,
355 b"-May-" => 5,
356 b"-Jun-" => 6,
357 b"-Jul-" => 7,
358 b"-Aug-" => 8,
359 b"-Sep-" => 9,
360 b"-Oct-" => 10,
361 b"-Nov-" => 11,
362 b"-Dec-" => 12,
363 _ => return Err(Error(())),
364 },
365 year,
366 wday,
367 })
368}
369
370fn parse_asctime(s: &[u8]) -> Result<HttpDate, Error> {
371 // Example: `Sun Nov 6 08:49:37 1994`
372 if s.len() != 24 || s[10] != b' ' || s[13] != b':' || s[16] != b':' || s[19] != b' ' {
373 return Err(Error(()));
374 }
375 Ok(HttpDate {
376 sec: toint_2(&s[17..19])?,
377 min: toint_2(&s[14..16])?,
378 hour: toint_2(&s[11..13])?,
379 day: {
380 let x = &s[8..10];
381 {
382 if x[0] == b' ' {
383 toint_1(x[1])
384 } else {
385 toint_2(x)
386 }
387 }?
388 },
389 mon: match &s[4..8] {
390 b"Jan " => 1,
391 b"Feb " => 2,
392 b"Mar " => 3,
393 b"Apr " => 4,
394 b"May " => 5,
395 b"Jun " => 6,
396 b"Jul " => 7,
397 b"Aug " => 8,
398 b"Sep " => 9,
399 b"Oct " => 10,
400 b"Nov " => 11,
401 b"Dec " => 12,
402 _ => return Err(Error(())),
403 },
404 year: toint_4(&s[20..24])?,
405 wday: match &s[0..4] {
406 b"Mon " => 1,
407 b"Tue " => 2,
408 b"Wed " => 3,
409 b"Thu " => 4,
410 b"Fri " => 5,
411 b"Sat " => 6,
412 b"Sun " => 7,
413 _ => return Err(Error(())),
414 },
415 })
416}
417
418fn is_leap_year(y: u16) -> bool {
419 y % 4 == 0 && (y % 100 != 0 || y % 400 == 0)
420}
421