1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
use std::{
    fmt::{self, Display, Write},
    str::FromStr,
};

use super::{HeaderValue, InvalidHeaderValue, TryIntoHeaderValue, Writer, CONTENT_RANGE};
use crate::error::ParseError;

crate::http::header::common_header! {
    /// `Content-Range` header, defined
    /// in [RFC 7233 §4.2](https://datatracker.ietf.org/doc/html/rfc7233#section-4.2)
    (ContentRange, CONTENT_RANGE) => [ContentRangeSpec]

    test_parse_and_format {
        crate::http::header::common_header_test!(test_bytes,
            vec![b"bytes 0-499/500"],
            Some(ContentRange(ContentRangeSpec::Bytes {
                range: Some((0, 499)),
                instance_length: Some(500)
            })));

        crate::http::header::common_header_test!(test_bytes_unknown_len,
            vec![b"bytes 0-499/*"],
            Some(ContentRange(ContentRangeSpec::Bytes {
                range: Some((0, 499)),
                instance_length: None
            })));

        crate::http::header::common_header_test!(test_bytes_unknown_range,
            vec![b"bytes */500"],
            Some(ContentRange(ContentRangeSpec::Bytes {
                range: None,
                instance_length: Some(500)
            })));

        crate::http::header::common_header_test!(test_unregistered,
            vec![b"seconds 1-2"],
            Some(ContentRange(ContentRangeSpec::Unregistered {
                unit: "seconds".to_owned(),
                resp: "1-2".to_owned()
            })));

        crate::http::header::common_header_test!(test_no_len,
            vec![b"bytes 0-499"],
            None::<ContentRange>);

        crate::http::header::common_header_test!(test_only_unit,
            vec![b"bytes"],
            None::<ContentRange>);

        crate::http::header::common_header_test!(test_end_less_than_start,
            vec![b"bytes 499-0/500"],
            None::<ContentRange>);

        crate::http::header::common_header_test!(test_blank,
            vec![b""],
            None::<ContentRange>);

        crate::http::header::common_header_test!(test_bytes_many_spaces,
            vec![b"bytes 1-2/500 3"],
            None::<ContentRange>);

        crate::http::header::common_header_test!(test_bytes_many_slashes,
            vec![b"bytes 1-2/500/600"],
            None::<ContentRange>);

        crate::http::header::common_header_test!(test_bytes_many_dashes,
            vec![b"bytes 1-2-3/500"],
            None::<ContentRange>);

    }
}

/// Content-Range header, defined
/// in [RFC 7233 §4.2](https://datatracker.ietf.org/doc/html/rfc7233#section-4.2)
///
/// # ABNF
/// ```plain
/// Content-Range       = byte-content-range
///                     / other-content-range
///
/// byte-content-range  = bytes-unit SP
///                       ( byte-range-resp / unsatisfied-range )
///
/// byte-range-resp     = byte-range "/" ( complete-length / "*" )
/// byte-range          = first-byte-pos "-" last-byte-pos
/// unsatisfied-range   = "*/" complete-length
///
/// complete-length     = 1*DIGIT
///
/// other-content-range = other-range-unit SP other-range-resp
/// other-range-resp    = *CHAR
/// ```
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum ContentRangeSpec {
    /// Byte range
    Bytes {
        /// First and last bytes of the range, omitted if request could not be
        /// satisfied
        range: Option<(u64, u64)>,

        /// Total length of the instance, can be omitted if unknown
        instance_length: Option<u64>,
    },

    /// Custom range, with unit not registered at IANA
    Unregistered {
        /// other-range-unit
        unit: String,

        /// other-range-resp
        resp: String,
    },
}

fn split_in_two(s: &str, separator: char) -> Option<(&str, &str)> {
    let mut iter = s.splitn(2, separator);
    match (iter.next(), iter.next()) {
        (Some(a), Some(b)) => Some((a, b)),
        _ => None,
    }
}

impl FromStr for ContentRangeSpec {
    type Err = ParseError;

    fn from_str(s: &str) -> Result<Self, ParseError> {
        let res = match split_in_two(s, ' ') {
            Some(("bytes", resp)) => {
                let (range, instance_length) =
                    split_in_two(resp, '/').ok_or(ParseError::Header)?;

                let instance_length = if instance_length == "*" {
                    None
                } else {
                    Some(instance_length.parse().map_err(|_| ParseError::Header)?)
                };

                let range = if range == "*" {
                    None
                } else {
                    let (first_byte, last_byte) =
                        split_in_two(range, '-').ok_or(ParseError::Header)?;
                    let first_byte = first_byte.parse().map_err(|_| ParseError::Header)?;
                    let last_byte = last_byte.parse().map_err(|_| ParseError::Header)?;
                    if last_byte < first_byte {
                        return Err(ParseError::Header);
                    }
                    Some((first_byte, last_byte))
                };

                ContentRangeSpec::Bytes {
                    range,
                    instance_length,
                }
            }
            Some((unit, resp)) => ContentRangeSpec::Unregistered {
                unit: unit.to_owned(),
                resp: resp.to_owned(),
            },
            _ => return Err(ParseError::Header),
        };
        Ok(res)
    }
}

impl Display for ContentRangeSpec {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match *self {
            ContentRangeSpec::Bytes {
                range,
                instance_length,
            } => {
                f.write_str("bytes ")?;
                match range {
                    Some((first_byte, last_byte)) => {
                        write!(f, "{}-{}", first_byte, last_byte)?;
                    }
                    None => {
                        f.write_str("*")?;
                    }
                };
                f.write_str("/")?;
                if let Some(v) = instance_length {
                    write!(f, "{}", v)
                } else {
                    f.write_str("*")
                }
            }
            ContentRangeSpec::Unregistered { ref unit, ref resp } => {
                f.write_str(unit)?;
                f.write_str(" ")?;
                f.write_str(resp)
            }
        }
    }
}

impl TryIntoHeaderValue for ContentRangeSpec {
    type Error = InvalidHeaderValue;

    fn try_into_value(self) -> Result<HeaderValue, Self::Error> {
        let mut writer = Writer::new();
        let _ = write!(&mut writer, "{}", self);
        HeaderValue::from_maybe_shared(writer.take())
    }
}