/// HTTP Range header representation.
#[derive(Debug, Clone, Copy)]
pub struct HttpRange {
pub start: u64,
pub length: u64,
}
static PREFIX: &str = "bytes=";
const PREFIX_LEN: usize = 6;
impl HttpRange {
/// Parses Range HTTP header string as per RFC 2616.
///
/// `header` is HTTP Range header (e.g. `bytes=bytes=0-9`).
/// `size` is full size of response (file).
pub fn parse(header: &str, size: u64) -> Result<Vec<HttpRange>, ()> {
if header.is_empty() {
return Ok(Vec::new());
}
if !header.starts_with(PREFIX) {
return Err(());
}
let size_sig = size as i64;
let mut no_overlap = false;
let all_ranges: Vec<Option<HttpRange>> = header[PREFIX_LEN..]
.split(',')
.map(|x| x.trim())
.filter(|x| !x.is_empty())
.map(|ra| {
let mut start_end_iter = ra.split('-');
let start_str = start_end_iter.next().ok_or(())?.trim();
let end_str = start_end_iter.next().ok_or(())?.trim();
if start_str.is_empty() {
// If no start is specified, end specifies the
// range start relative to the end of the file.
let mut length: i64 = end_str.parse().map_err(|_| ())?;
if length > size_sig {
length = size_sig;
}
Ok(Some(HttpRange {
start: (size_sig - length) as u64,
length: length as u64,
}))
} else {
let start: i64 = start_str.parse().map_err(|_| ())?;
if start < 0 {
return Err(());
}
if start >= size_sig {
no_overlap = true;
return Ok(None);
}
let length = if end_str.is_empty() {
// If no end is specified, range extends to end of the file.
size_sig - start
} else {
let mut end: i64 = end_str.parse().map_err(|_| ())?;
if start > end {
return Err(());
}
if end >= size_sig {
end = size_sig - 1;
}
end - start + 1
};
Ok(Some(HttpRange {
start: start as u64,
length: length as u64,
}))
}
})
.collect::<Result<_, _>>()?;
let ranges: Vec<HttpRange> = all_ranges.into_iter().filter_map(|x| x).collect();
if no_overlap && ranges.is_empty() {
return Err(());
}
Ok(ranges)
}
}
#[cfg(test)]
mod tests {
use super::*;
struct T(&'static str, u64, Vec<HttpRange>);
#[test]
fn test_parse() {
let tests = vec![
T("", 0, vec![]),
T("", 1000, vec![]),
T("foo", 0, vec![]),
T("bytes=", 0, vec![]),
T("bytes=7", 10, vec![]),
T("bytes= 7 ", 10, vec![]),
T("bytes=1-", 0, vec![]),
T("bytes=5-4", 10, vec![]),
T("bytes=0-2,5-4", 10, vec![]),
T("bytes=2-5,4-3", 10, vec![]),
T("bytes=--5,4--3", 10, vec![]),
T("bytes=A-", 10, vec![]),
T("bytes=A- ", 10, vec![]),
T("bytes=A-Z", 10, vec![]),
T("bytes= -Z", 10, vec![]),
T("bytes=5-Z", 10, vec![]),
T("bytes=Ran-dom, garbage", 10, vec![]),
T("bytes=0x01-0x02", 10, vec![]),
T("bytes= ", 10, vec![]),
T("bytes= , , , ", 10, vec![]),
T(
"bytes=0-9",
10,
vec![HttpRange {
start: 0,
length: 10,
}],
),
T(
"bytes=0-",
10,
vec![HttpRange {
start: 0,
length: 10,
}],
),
T(
"bytes=5-",
10,
vec![HttpRange {
start: 5,
length: 5,
}],
),
T(
"bytes=0-20",
10,
vec![HttpRange {
start: 0,
length: 10,
}],
),
T(
"bytes=15-,0-5",
10,
vec![HttpRange {
start: 0,
length: 6,
}],
),
T(
"bytes=1-2,5-",
10,
vec![
HttpRange {
start: 1,
length: 2,
},
HttpRange {
start: 5,
length: 5,
},
],
),
T(
"bytes=-2 , 7-",
11,
vec![
HttpRange {
start: 9,
length: 2,
},
HttpRange {
start: 7,
length: 4,
},
],
),
T(
"bytes=0-0 ,2-2, 7-",
11,
vec![
HttpRange {
start: 0,
length: 1,
},
HttpRange {
start: 2,
length: 1,
},
HttpRange {
start: 7,
length: 4,
},
],
),
T(
"bytes=-5",
10,
vec![HttpRange {
start: 5,
length: 5,
}],
),
T(
"bytes=-15",
10,
vec![HttpRange {
start: 0,
length: 10,
}],
),
T(
"bytes=0-499",
10000,
vec![HttpRange {
start: 0,
length: 500,
}],
),
T(
"bytes=500-999",
10000,
vec![HttpRange {
start: 500,
length: 500,
}],
),
T(
"bytes=-500",
10000,
vec![HttpRange {
start: 9500,
length: 500,
}],
),
T(
"bytes=9500-",
10000,
vec![HttpRange {
start: 9500,
length: 500,
}],
),
T(
"bytes=0-0,-1",
10000,
vec![
HttpRange {
start: 0,
length: 1,
},
HttpRange {
start: 9999,
length: 1,
},
],
),
T(
"bytes=500-600,601-999",
10000,
vec![
HttpRange {
start: 500,
length: 101,
},
HttpRange {
start: 601,
length: 399,
},
],
),
T(
"bytes=500-700,601-999",
10000,
vec![
HttpRange {
start: 500,
length: 201,
},
HttpRange {
start: 601,
length: 399,
},
],
),
// Match Apache laxity:
T(
"bytes= 1 -2 , 4- 5, 7 - 8 , ,,",
11,
vec![
HttpRange {
start: 1,
length: 2,
},
HttpRange {
start: 4,
length: 2,
},
HttpRange {
start: 7,
length: 2,
},
],
),
];
for t in tests {
let header = t.0;
let size = t.1;
let expected = t.2;
let res = HttpRange::parse(header, size);
if res.is_err() {
if expected.is_empty() {
continue;
} else {
assert!(
false,
"parse({}, {}) returned error {:?}",
header,
size,
res.unwrap_err()
);
}
}
let got = res.unwrap();
if got.len() != expected.len() {
assert!(
false,
"len(parseRange({}, {})) = {}, want {}",
header,
size,
got.len(),
expected.len()
);
continue;
}
for i in 0..expected.len() {
if got[i].start != expected[i].start {
assert!(
false,
"parseRange({}, {})[{}].start = {}, want {}",
header, size, i, got[i].start, expected[i].start
)
}
if got[i].length != expected[i].length {
assert!(
false,
"parseRange({}, {})[{}].length = {}, want {}",
header, size, i, got[i].length, expected[i].length
)
}
}
}
}
}