httpdate/
date.rs

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

httpdate/
date.rs
