http_types/
parse_utils.rs

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1use std::borrow::Cow;
2
3/// https://tools.ietf.org/html/rfc7230#section-3.2.6
4pub(crate) fn parse_token(input: &str) -> (Option<&str>, &str) {
5    let mut end_of_token = 0;
6    for (i, c) in input.char_indices() {
7        if tchar(c) {
8            end_of_token = i + 1;
9        } else {
10            break;
11        }
12    }
13
14    if end_of_token == 0 {
15        (None, input)
16    } else {
17        (Some(&input[..end_of_token]), &input[end_of_token..])
18    }
19}
20
21/// https://tools.ietf.org/html/rfc7230#section-3.2.6
22fn tchar(c: char) -> bool {
23    matches!(
24        c, 'a'..='z'
25            | 'A'..='Z'
26            | '0'..='9'
27            | '!'
28            | '#'
29            | '$'
30            | '%'
31            | '&'
32            | '\''
33            | '*'
34            | '+'
35            | '-'
36            | '.'
37            | '^'
38            | '_'
39            | '`'
40            | '|'
41            | '~'
42    )
43}
44
45/// https://tools.ietf.org/html/rfc7230#section-3.2.6
46fn vchar(c: char) -> bool {
47    matches!(c as u8, b'\t' | 32..=126 | 128..=255)
48}
49
50/// https://tools.ietf.org/html/rfc7230#section-3.2.6
51pub(crate) fn parse_quoted_string(input: &str) -> (Option<Cow<'_, str>>, &str) {
52    // quoted-string must start with a DQUOTE
53    if !input.starts_with('"') {
54        return (None, input);
55    }
56
57    let mut end_of_string = None;
58    let mut backslashes: Vec<usize> = vec![];
59
60    for (i, c) in input.char_indices().skip(1) {
61        if i > 1 && backslashes.last() == Some(&(i - 2)) {
62            if !vchar(c) {
63                // only VCHARs can be escaped
64                return (None, input);
65            }
66        // otherwise, we skip over this character while parsing
67        } else {
68            match c as u8 {
69                // we have reached a quoted-pair
70                b'\\' => {
71                    backslashes.push(i - 1);
72                }
73
74                // end of the string, DQUOTE
75                b'"' => {
76                    end_of_string = Some(i + 1);
77                    break;
78                }
79
80                // qdtext
81                b'\t' | b' ' | 15 | 35..=91 | 93..=126 | 128..=255 => {}
82
83                // unexpected character, bail
84                _ => return (None, input),
85            }
86        }
87    }
88
89    if let Some(end_of_string) = end_of_string {
90        let value = &input[1..end_of_string - 1]; // strip DQUOTEs from start and end
91
92        let value = if backslashes.is_empty() {
93            // no backslashes means we don't need to allocate
94            value.into()
95        } else {
96            backslashes.reverse(); // so that we can use pop. goes from low-to-high to high-to-low sorting
97
98            value
99                .char_indices()
100                .filter_map(|(i, c)| {
101                    if Some(&i) == backslashes.last() {
102                        // they're already sorted highest to lowest, so we only need to check the last one
103                        backslashes.pop();
104                        None // remove the backslash from the output
105                    } else {
106                        Some(c)
107                    }
108                })
109                .collect::<String>()
110                .into()
111        };
112
113        (Some(value), &input[end_of_string..])
114    } else {
115        // we never reached a closing DQUOTE, so we do not have a valid quoted-string
116        (None, input)
117    }
118}
119
120#[cfg(test)]
121mod test {
122    use super::*;
123    #[test]
124    fn token_successful_parses() {
125        assert_eq!(parse_token("key=value"), (Some("key"), "=value"));
126        assert_eq!(parse_token("KEY=value"), (Some("KEY"), "=value"));
127        assert_eq!(parse_token("0123)=value"), (Some("0123"), ")=value"));
128        assert_eq!(parse_token("a=b"), (Some("a"), "=b"));
129        assert_eq!(
130            parse_token("!#$%&'*+-.^_`|~=value"),
131            (Some("!#$%&'*+-.^_`|~"), "=value",)
132        );
133    }
134
135    #[test]
136    fn token_unsuccessful_parses() {
137        assert_eq!(parse_token(""), (None, ""));
138        assert_eq!(parse_token("=value"), (None, "=value"));
139        for c in r#"(),/:;<=>?@[\]{}"#.chars() {
140            let s = c.to_string();
141            assert_eq!(parse_token(&s), (None, &*s));
142
143            let s = format!("match{}rest", s);
144            assert_eq!(parse_token(&s), (Some("match"), &*format!("{}rest", c)));
145        }
146    }
147
148    #[test]
149    fn qstring_successful_parses() {
150        assert_eq!(
151            parse_quoted_string(r#""key"=value"#),
152            (Some(Cow::Borrowed("key")), "=value")
153        );
154
155        assert_eq!(
156            parse_quoted_string(r#""escaped \" quote \""rest"#),
157            (
158                Some(Cow::Owned(String::from(r#"escaped " quote ""#))),
159                r#"rest"#
160            )
161        );
162    }
163
164    #[test]
165    fn qstring_unsuccessful_parses() {
166        assert_eq!(parse_quoted_string(r#""abc"#), (None, "\"abc"));
167        assert_eq!(parse_quoted_string(r#"hello""#), (None, "hello\"",));
168        assert_eq!(parse_quoted_string(r#"=value\"#), (None, "=value\\"));
169        assert_eq!(parse_quoted_string(r#"\""#), (None, r#"\""#));
170        assert_eq!(parse_quoted_string(r#""\""#), (None, r#""\""#));
171    }
172}
http_types/parse_utils.rs

http_types/
parse_utils.rs
