ruma_common/
http_headers.rs

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1//! Helpers for HTTP headers.
2
3use std::borrow::Cow;
4
5mod content_disposition;
6mod rfc8187;
7
8pub use self::content_disposition::{
9    ContentDisposition, ContentDispositionParseError, ContentDispositionType, TokenString,
10    TokenStringParseError,
11};
12
13/// Whether the given byte is a [`token` char].
14///
15/// [`token` char]: https://datatracker.ietf.org/doc/html/rfc9110#section-5.6.2
16pub const fn is_tchar(b: u8) -> bool {
17    b.is_ascii_alphanumeric()
18        || matches!(
19            b,
20            b'!' | b'#'
21                | b'$'
22                | b'%'
23                | b'&'
24                | b'\''
25                | b'*'
26                | b'+'
27                | b'-'
28                | b'.'
29                | b'^'
30                | b'_'
31                | b'`'
32                | b'|'
33                | b'~'
34        )
35}
36
37/// Whether the given bytes slice is a [`token`].
38///
39/// [`token`]: https://datatracker.ietf.org/doc/html/rfc9110#section-5.6.2
40pub fn is_token(bytes: &[u8]) -> bool {
41    bytes.iter().all(|b| is_tchar(*b))
42}
43
44/// Whether the given string is a [`token`].
45///
46/// [`token`]: https://datatracker.ietf.org/doc/html/rfc9110#section-5.6.2
47pub fn is_token_string(s: &str) -> bool {
48    is_token(s.as_bytes())
49}
50
51/// Whether the given char is a [visible US-ASCII char].
52///
53/// [visible US-ASCII char]: https://datatracker.ietf.org/doc/html/rfc5234#appendix-B.1
54pub const fn is_vchar(c: char) -> bool {
55    matches!(c, '\x21'..='\x7E')
56}
57
58/// Whether the given char is in the US-ASCII character set and allowed inside a [quoted string].
59///
60/// Contrary to the definition of quoted strings, this doesn't allow `obs-text` characters, i.e.
61/// non-US-ASCII characters, as we usually deal with UTF-8 strings rather than ISO-8859-1 strings.
62///
63/// [quoted string]: https://datatracker.ietf.org/doc/html/rfc9110#section-5.6.4
64pub const fn is_ascii_string_quotable(c: char) -> bool {
65    is_vchar(c) || matches!(c, '\x09' | '\x20')
66}
67
68/// Remove characters that do not pass [`is_ascii_string_quotable()`] from the given string.
69///
70/// [quoted string]: https://datatracker.ietf.org/doc/html/rfc9110#section-5.6.4
71pub fn sanitize_for_ascii_quoted_string(value: &str) -> Cow<'_, str> {
72    if value.chars().all(is_ascii_string_quotable) {
73        return Cow::Borrowed(value);
74    }
75
76    Cow::Owned(value.chars().filter(|c| is_ascii_string_quotable(*c)).collect())
77}
78
79/// If the US-ASCII field value does not contain only token chars, convert it to a [quoted string].
80///
81/// The string should be sanitized with [`sanitize_for_ascii_quoted_string()`] or should only
82/// contain characters that pass [`is_ascii_string_quotable()`].
83///
84/// [quoted string]: https://datatracker.ietf.org/doc/html/rfc9110#section-5.6.4
85pub fn quote_ascii_string_if_required(value: &str) -> Cow<'_, str> {
86    if !value.is_empty() && is_token_string(value) {
87        return Cow::Borrowed(value);
88    }
89
90    let value = value.replace('\\', r#"\\"#).replace('"', r#"\""#);
91    Cow::Owned(format!("\"{value}\""))
92}
93
94/// Removes the escape backslashes in the given string.
95pub fn unescape_string(s: &str) -> String {
96    let mut is_escaped = false;
97
98    s.chars()
99        .filter(|c| {
100            is_escaped = *c == '\\' && !is_escaped;
101            !is_escaped
102        })
103        .collect()
104}
ruma_common/http_headers.rs

ruma_common/
http_headers.rs
