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|
//! Utilities to make urls safe.
use crate::util::encode::encode;
/// Make a value safe for injection as a URL.
///
/// This encodes unsafe characters with percent-encoding and skips already
/// encoded sequences (see [`normalize_uri`][] below).
/// Further unsafe characters are encoded as character references (see
/// [`encode`][]).
///
/// Then, a vec of (lowercase) allowed protocols can be given, in which case
/// the URL is sanitized.
///
/// For example, `Some(vec!["http", "https", "irc", "ircs", "mailto", "xmpp"])`
/// can be used for `a[href]`, or `Some(vec!["http", "https"])` for `img[src]`.
/// If the URL includes an unknown protocol (one not matched by `protocol`, such
/// as a dangerous example, `javascript:`), the value is ignored.
///
/// ## Examples
///
/// ```rust ignore
/// use micromark::util::sanitize_url::sanitize_url;
///
/// assert_eq!(sanitize_uri("javascript:alert(1)", &None), "javascript:alert(1)");
/// assert_eq!(sanitize_uri("javascript:alert(1)", &Some(vec!["http", "https"])), "");
/// assert_eq!(sanitize_uri("https://example.com", &Some(vec!["http", "https"])), "https://example.com");
/// assert_eq!(sanitize_uri("https://a👍b.c/%20/%", &Some(vec!["http", "https"])), "https://a%F0%9F%91%8Db.c/%20/%25");
/// ```
///
/// ## References
///
/// * [`micromark-util-sanitize-uri` in `micromark`](https://github.com/micromark/micromark/tree/main/packages/micromark-util-sanitize-uri)
pub fn sanitize_uri(value: &str, protocols: &Option<Vec<&str>>) -> String {
let value = encode(normalize_uri(value), true);
if let Some(protocols) = protocols {
let end = value.find(|c| matches!(c, '?' | '#' | '/'));
let mut colon = value.find(|c| matches!(c, ':'));
// If the first colon is after `?`, `#`, or `/`, it’s not a protocol.
if let Some(end) = end {
if let Some(index) = colon {
if index > end {
colon = None;
}
}
}
// If there is no protocol, it’s relative, and fine.
if let Some(colon) = colon {
// If it is a protocol, it should be allowed.
let protocol = value[0..colon].to_lowercase();
if !protocols.contains(&protocol.as_str()) {
return "".to_string();
}
}
}
value
}
/// Normalize a URL (such as used in definitions).
///
/// Encode unsafe characters with percent-encoding, skipping already encoded
/// sequences.
///
/// ## Examples
///
/// ```rust ignore
/// use micromark::util::sanitize_url::normalize_uri;
///
/// assert_eq!(sanitize_uri("https://example.com"), "https://example.com");
/// assert_eq!(sanitize_uri("https://a👍b.c/%20/%"), "https://a%F0%9F%91%8Db.c/%20/%25");
/// ```
///
/// ## References
///
/// * [`micromark-util-sanitize-uri` in `micromark`](https://github.com/micromark/micromark/tree/main/packages/micromark-util-sanitize-uri)
fn normalize_uri(value: &str) -> String {
let chars = value.chars().collect::<Vec<_>>();
// Note: it’ll grow bigger for each non-ascii or non-safe character.
let mut result = String::with_capacity(value.len());
let mut index = 0;
let mut start = 0;
let mut buff = [0; 4];
while index < chars.len() {
let char = chars[index];
// A correct percent encoded value.
if char == '%'
&& index + 2 < chars.len()
&& chars[index + 1].is_ascii_alphanumeric()
&& chars[index + 2].is_ascii_alphanumeric()
{
index += 3;
continue;
}
// Note: Rust already takes care of lone surrogates.
// Non-ascii or not allowed ascii.
if char >= '\u{0080}'
|| !matches!(char, '!' | '#' | '$' | '&'..=';' | '=' | '?'..='Z' | '_' | 'a'..='z' | '~')
{
result.push_str(&chars[start..index].iter().collect::<String>());
char.encode_utf8(&mut buff);
result.push_str(
&buff[0..char.len_utf8()]
.iter()
.map(|&byte| format!("%{:>02X}", byte))
.collect::<String>(),
);
start = index + 1;
}
index += 1;
}
result.push_str(&chars[start..].iter().collect::<String>());
result
}
|
