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proto: avoid panicking in parse_time() #1964

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Jun 9, 2023
Merged

proto: avoid panicking in parse_time() #1964

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85 changes: 45 additions & 40 deletions crates/proto/src/serialize/txt/zone.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -382,6 +382,7 @@ impl Parser {
///
/// assert_eq!(Parser::parse_time("0").unwrap(), 0);
/// assert!(Parser::parse_time("s").is_err());
/// assert!(Parser::parse_time("").is_err());
/// assert_eq!(Parser::parse_time("0s").unwrap(), 0);
/// assert_eq!(Parser::parse_time("1").unwrap(), 1);
/// assert_eq!(Parser::parse_time("1S").unwrap(), 1);
Expand All @@ -396,52 +397,56 @@ impl Parser {
/// assert_eq!(Parser::parse_time("1w").unwrap(), 604800);
/// assert_eq!(Parser::parse_time("1s2d3w4h2m").unwrap(), 1+2*86400+3*604800+4*3600+2*60);
/// assert_eq!(Parser::parse_time("3w3w").unwrap(), 3*604800+3*604800);
/// assert!(Parser::parse_time("7102w").is_err());
/// ```
pub fn parse_time(ttl_str: &str) -> ParseResult<u32> {
let mut value: u32 = 0;
let mut collect: Option<u32> = None;

for c in ttl_str.chars() {
match c {
// TODO, should these all be checked operations?
'0'..='9' => {
let digit = c.to_digit(10).ok_or(ParseErrorKind::CharToInt(c))?;
collect = Some(collect.unwrap_or(0) * 10 + digit);
}
'S' | 's' => {
value += collect
.take()
.ok_or_else(|| ParseErrorKind::ParseTime(ttl_str.to_string()))?
}
'M' | 'm' => {
value += 60
* collect
.take()
.ok_or_else(|| ParseErrorKind::ParseTime(ttl_str.to_string()))?
}
'H' | 'h' => {
value += 3_600
* collect
.take()
.ok_or_else(|| ParseErrorKind::ParseTime(ttl_str.to_string()))?
}
'D' | 'd' => {
value += 86_400
* collect
.take()
.ok_or_else(|| ParseErrorKind::ParseTime(ttl_str.to_string()))?
}
'W' | 'w' => {
value += 604_800
* collect
.take()
.ok_or_else(|| ParseErrorKind::ParseTime(ttl_str.to_string()))?
if ttl_str.is_empty() {
return Err(ParseErrorKind::ParseTime(ttl_str.to_string()).into());
}

let (mut state, mut value) = (None, 0_u32);
for (i, c) in ttl_str.chars().enumerate() {
let start = match (state, c) {
(None, '0'..='9') => {
state = Some(i);
continue;
}
(Some(_), '0'..='9') => continue,
(Some(start), 'S' | 's' | 'M' | 'm' | 'H' | 'h' | 'D' | 'd' | 'W' | 'w') => start,
_ => return Err(ParseErrorKind::ParseTime(ttl_str.to_string()).into()),
}
};

// All allowed chars are ASCII, so using char indexes to slice &[u8] is OK
let number = u32::from_str(&ttl_str[start..i])
.map_err(|_| ParseErrorKind::ParseTime(ttl_str.to_string()))?;

let multiplier = match c {
'S' | 's' => 1,
'M' | 'm' => 60,
'H' | 'h' => 3_600,
'D' | 'd' => 86_400,
'W' | 'w' => 604_800,
_ => unreachable!(),
};

value = number
.checked_mul(multiplier)
.and_then(|add| value.checked_add(add))
.ok_or_else(|| ParseErrorKind::ParseTime(ttl_str.to_string()))?;

state = None;
}

if let Some(start) = state {
// All allowed chars are ASCII, so using char indexes to slice &[u8] is OK
let number = u32::from_str(&ttl_str[start..])
.map_err(|_| ParseErrorKind::ParseTime(ttl_str.to_string()))?;
value = value
.checked_add(number)
.ok_or_else(|| ParseErrorKind::ParseTime(ttl_str.to_string()))?;
}

Ok(value + collect.unwrap_or(0)) // collects the initial num, or 0 if it was already collected
Ok(value)
}
}

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