use std::cmp;
use std::fmt::{self, Display, Formatter};
use std::str::FromStr;
use std::time::{Duration, SystemTime, UNIX_EPOCH};
use crate::Error;
#[derive(Copy, Clone, Debug, Eq, PartialEq, Hash)]
pub struct HttpDate {
sec: u8,
min: u8,
hour: u8,
day: u8,
mon: u8,
year: u16,
wday: u8,
}
impl HttpDate {
fn is_valid(&self) -> bool {
self.sec < 60
&& self.min < 60
&& self.hour < 24
&& self.day > 0
&& self.day < 32
&& self.mon > 0
&& self.mon <= 12
&& self.year >= 1970
&& self.year <= 9999
&& &HttpDate::from(SystemTime::from(*self)) == self
}
}
impl From<SystemTime> for HttpDate {
fn from(v: SystemTime) -> HttpDate {
let dur = v
.duration_since(UNIX_EPOCH)
.expect("all times should be after the epoch");
let secs_since_epoch = dur.as_secs();
if secs_since_epoch >= 253402300800 {
panic!("date must be before year 9999");
}
const LEAPOCH: i64 = 11017;
const DAYS_PER_400Y: i64 = 365 * 400 + 97;
const DAYS_PER_100Y: i64 = 365 * 100 + 24;
const DAYS_PER_4Y: i64 = 365 * 4 + 1;
let days = (secs_since_epoch / 86400) as i64 - LEAPOCH;
let secs_of_day = secs_since_epoch % 86400;
let mut qc_cycles = days / DAYS_PER_400Y;
let mut remdays = days % DAYS_PER_400Y;
if remdays < 0 {
remdays += DAYS_PER_400Y;
qc_cycles -= 1;
}
let mut c_cycles = remdays / DAYS_PER_100Y;
if c_cycles == 4 {
c_cycles -= 1;
}
remdays -= c_cycles * DAYS_PER_100Y;
let mut q_cycles = remdays / DAYS_PER_4Y;
if q_cycles == 25 {
q_cycles -= 1;
}
remdays -= q_cycles * DAYS_PER_4Y;
let mut remyears = remdays / 365;
if remyears == 4 {
remyears -= 1;
}
remdays -= remyears * 365;
let mut year = 2000 + remyears + 4 * q_cycles + 100 * c_cycles + 400 * qc_cycles;
let months = [31, 30, 31, 30, 31, 31, 30, 31, 30, 31, 31, 29];
let mut mon = 0;
for mon_len in months.iter() {
mon += 1;
if remdays < *mon_len {
break;
}
remdays -= *mon_len;
}
let mday = remdays + 1;
let mon = if mon + 2 > 12 {
year += 1;
mon - 10
} else {
mon + 2
};
let mut wday = (3 + days) % 7;
if wday <= 0 {
wday += 7
};
HttpDate {
sec: (secs_of_day % 60) as u8,
min: ((secs_of_day % 3600) / 60) as u8,
hour: (secs_of_day / 3600) as u8,
day: mday as u8,
mon: mon as u8,
year: year as u16,
wday: wday as u8,
}
}
}
impl From<HttpDate> for SystemTime {
fn from(v: HttpDate) -> SystemTime {
let leap_years =
((v.year - 1) - 1968) / 4 - ((v.year - 1) - 1900) / 100 + ((v.year - 1) - 1600) / 400;
let mut ydays = match v.mon {
1 => 0,
2 => 31,
3 => 59,
4 => 90,
5 => 120,
6 => 151,
7 => 181,
8 => 212,
9 => 243,
10 => 273,
11 => 304,
12 => 334,
_ => unreachable!(),
} + v.day as u64
- 1;
if is_leap_year(v.year) && v.mon > 2 {
ydays += 1;
}
let days = (v.year as u64 - 1970) * 365 + leap_years as u64 + ydays;
UNIX_EPOCH
+ Duration::from_secs(
v.sec as u64 + v.min as u64 * 60 + v.hour as u64 * 3600 + days * 86400,
)
}
}
impl FromStr for HttpDate {
type Err = Error;
fn from_str(s: &str) -> Result<HttpDate, Error> {
if !s.is_ascii() {
return Err(Error(()));
}
let x = s.trim().as_bytes();
let date = parse_imf_fixdate(x)
.or_else(|_| parse_rfc850_date(x))
.or_else(|_| parse_asctime(x))?;
if !date.is_valid() {
return Err(Error(()));
}
Ok(date)
}
}
impl Display for HttpDate {
fn fmt(&self, f: &mut Formatter) -> fmt::Result {
let wday = match self.wday {
1 => b"Mon",
2 => b"Tue",
3 => b"Wed",
4 => b"Thu",
5 => b"Fri",
6 => b"Sat",
7 => b"Sun",
_ => unreachable!(),
};
let mon = match self.mon {
1 => b"Jan",
2 => b"Feb",
3 => b"Mar",
4 => b"Apr",
5 => b"May",
6 => b"Jun",
7 => b"Jul",
8 => b"Aug",
9 => b"Sep",
10 => b"Oct",
11 => b"Nov",
12 => b"Dec",
_ => unreachable!(),
};
let mut buf: [u8; 29] = *b" , 00 0000 00:00:00 GMT";
buf[0] = wday[0];
buf[1] = wday[1];
buf[2] = wday[2];
buf[5] = b'0' + (self.day / 10);
buf[6] = b'0' + (self.day % 10);
buf[8] = mon[0];
buf[9] = mon[1];
buf[10] = mon[2];
buf[12] = b'0' + (self.year / 1000) as u8;
buf[13] = b'0' + (self.year / 100 % 10) as u8;
buf[14] = b'0' + (self.year / 10 % 10) as u8;
buf[15] = b'0' + (self.year % 10) as u8;
buf[17] = b'0' + (self.hour / 10);
buf[18] = b'0' + (self.hour % 10);
buf[20] = b'0' + (self.min / 10);
buf[21] = b'0' + (self.min % 10);
buf[23] = b'0' + (self.sec / 10);
buf[24] = b'0' + (self.sec % 10);
f.write_str(std::str::from_utf8(&buf[..]).unwrap())
}
}
impl Ord for HttpDate {
fn cmp(&self, other: &HttpDate) -> cmp::Ordering {
SystemTime::from(*self).cmp(&SystemTime::from(*other))
}
}
impl PartialOrd for HttpDate {
fn partial_cmp(&self, other: &HttpDate) -> Option<cmp::Ordering> {
Some(self.cmp(other))
}
}
fn toint_1(x: u8) -> Result<u8, Error> {
let result = x.wrapping_sub(b'0');
if result < 10 {
Ok(result)
} else {
Err(Error(()))
}
}
fn toint_2(s: &[u8]) -> Result<u8, Error> {
let high = s[0].wrapping_sub(b'0');
let low = s[1].wrapping_sub(b'0');
if high < 10 && low < 10 {
Ok(high * 10 + low)
} else {
Err(Error(()))
}
}
#[allow(clippy::many_single_char_names)]
fn toint_4(s: &[u8]) -> Result<u16, Error> {
let a = u16::from(s[0].wrapping_sub(b'0'));
let b = u16::from(s[1].wrapping_sub(b'0'));
let c = u16::from(s[2].wrapping_sub(b'0'));
let d = u16::from(s[3].wrapping_sub(b'0'));
if a < 10 && b < 10 && c < 10 && d < 10 {
Ok(a * 1000 + b * 100 + c * 10 + d)
} else {
Err(Error(()))
}
}
fn parse_imf_fixdate(s: &[u8]) -> Result<HttpDate, Error> {
if s.len() != 29 || &s[25..] != b" GMT" || s[16] != b' ' || s[19] != b':' || s[22] != b':' {
return Err(Error(()));
}
Ok(HttpDate {
sec: toint_2(&s[23..25])?,
min: toint_2(&s[20..22])?,
hour: toint_2(&s[17..19])?,
day: toint_2(&s[5..7])?,
mon: match &s[7..12] {
b" Jan " => 1,
b" Feb " => 2,
b" Mar " => 3,
b" Apr " => 4,
b" May " => 5,
b" Jun " => 6,
b" Jul " => 7,
b" Aug " => 8,
b" Sep " => 9,
b" Oct " => 10,
b" Nov " => 11,
b" Dec " => 12,
_ => return Err(Error(())),
},
year: toint_4(&s[12..16])?,
wday: match &s[..5] {
b"Mon, " => 1,
b"Tue, " => 2,
b"Wed, " => 3,
b"Thu, " => 4,
b"Fri, " => 5,
b"Sat, " => 6,
b"Sun, " => 7,
_ => return Err(Error(())),
},
})
}
fn parse_rfc850_date(s: &[u8]) -> Result<HttpDate, Error> {
if s.len() < 23 {
return Err(Error(()));
}
fn wday<'a>(s: &'a [u8], wday: u8, name: &'static [u8]) -> Option<(u8, &'a [u8])> {
if &s[0..name.len()] == name {
return Some((wday, &s[name.len()..]));
}
None
}
let (wday, s) = wday(s, 1, b"Monday, ")
.or_else(|| wday(s, 2, b"Tuesday, "))
.or_else(|| wday(s, 3, b"Wednesday, "))
.or_else(|| wday(s, 4, b"Thursday, "))
.or_else(|| wday(s, 5, b"Friday, "))
.or_else(|| wday(s, 6, b"Saturday, "))
.or_else(|| wday(s, 7, b"Sunday, "))
.ok_or(Error(()))?;
if s.len() != 22 || s[12] != b':' || s[15] != b':' || &s[18..22] != b" GMT" {
return Err(Error(()));
}
let mut year = u16::from(toint_2(&s[7..9])?);
if year < 70 {
year += 2000;
} else {
year += 1900;
}
Ok(HttpDate {
sec: toint_2(&s[16..18])?,
min: toint_2(&s[13..15])?,
hour: toint_2(&s[10..12])?,
day: toint_2(&s[0..2])?,
mon: match &s[2..7] {
b"-Jan-" => 1,
b"-Feb-" => 2,
b"-Mar-" => 3,
b"-Apr-" => 4,
b"-May-" => 5,
b"-Jun-" => 6,
b"-Jul-" => 7,
b"-Aug-" => 8,
b"-Sep-" => 9,
b"-Oct-" => 10,
b"-Nov-" => 11,
b"-Dec-" => 12,
_ => return Err(Error(())),
},
year,
wday,
})
}
fn parse_asctime(s: &[u8]) -> Result<HttpDate, Error> {
if s.len() != 24 || s[10] != b' ' || s[13] != b':' || s[16] != b':' || s[19] != b' ' {
return Err(Error(()));
}
Ok(HttpDate {
sec: toint_2(&s[17..19])?,
min: toint_2(&s[14..16])?,
hour: toint_2(&s[11..13])?,
day: {
let x = &s[8..10];
{
if x[0] == b' ' {
toint_1(x[1])
} else {
toint_2(x)
}
}?
},
mon: match &s[4..8] {
b"Jan " => 1,
b"Feb " => 2,
b"Mar " => 3,
b"Apr " => 4,
b"May " => 5,
b"Jun " => 6,
b"Jul " => 7,
b"Aug " => 8,
b"Sep " => 9,
b"Oct " => 10,
b"Nov " => 11,
b"Dec " => 12,
_ => return Err(Error(())),
},
year: toint_4(&s[20..24])?,
wday: match &s[0..4] {
b"Mon " => 1,
b"Tue " => 2,
b"Wed " => 3,
b"Thu " => 4,
b"Fri " => 5,
b"Sat " => 6,
b"Sun " => 7,
_ => return Err(Error(())),
},
})
}
fn is_leap_year(y: u16) -> bool {
y % 4 == 0 && (y % 100 != 0 || y % 400 == 0)
}