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Convert compatible full-regex rules to content-blocking syntax #621

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Convert compatible full-regex rules to content-blocking syntax #621

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274 changes: 202 additions & 72 deletions src/content_blocking.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -301,6 +301,71 @@ impl Iterator for CbRuleEquivalentIterator {
}
}

/// Check if a regex pattern only uses features supported by content-blocking syntax.
///
/// Content blocking syntax supports:
/// - Literal characters
/// - `.` (any character)
/// - `[...]` character classes (including ranges and negation)
/// - `?`, `+`, `*` quantifiers
/// - `(...)` capturing groups
/// - Escaped special characters like `\.`, `\(`, etc.
fn is_cb_compatible_regex(pattern: &str) -> bool {
let mut chars = pattern.chars().peekable();
let mut in_char_class = false;
let mut paren_depth = 0;

while let Some(c) = chars.next() {
if in_char_class {
match c {
'\\' => {
// Any escape is valid inside a character class
chars.next();
}
']' => {
in_char_class = false;
}
_ => {}
}
} else {
match c {
'\\' => match chars.next() {
Some('\\') | Some('.') | Some('?') | Some('+') | Some('*') | Some('(')
| Some(')') | Some('[') | Some(']') | Some('^') | Some('$') | Some('-')
| Some('|') | Some('{') | Some('}') | Some('/') => {}
_ => return false,
},
'[' => {
in_char_class = true;
if chars.peek() == Some(&'^') {
chars.next();
}
if chars.peek() == Some(&']') {
chars.next(); // ] is literal when it's the first char
}
}
'(' => {
paren_depth += 1;
if chars.peek() == Some(&'?') {
return false;
}
}
')' => {
if paren_depth == 0 {
return false;
}
paren_depth -= 1;
}
'|' => return false,
'{' => return false,
_ => {}
}
}
}

!in_char_class && paren_depth == 0
}

impl TryFrom<NetworkFilter> for CbRuleEquivalent {
type Error = CbRuleCreationFailure;

Expand All @@ -325,9 +390,6 @@ impl TryFrom<NetworkFilter> for CbRuleEquivalent {
if v.is_csp() {
return Err(CbRuleCreationFailure::NetworkCspUnsupported);
}
if v.mask.contains(NetworkFilterMask::IS_COMPLETE_REGEX) {
return Err(CbRuleCreationFailure::FullRegexUnsupported);
}
if v.is_removeparam() {
return Err(CbRuleCreationFailure::NetworkRemoveparamUnsupported);
}
Expand All @@ -345,86 +407,154 @@ impl TryFrom<NetworkFilter> for CbRuleEquivalent {
vec![]
};

let url_filter = match (v.filter, v.hostname) {
(crate::filters::network::FilterPart::AnyOf(_), _) => {
return Err(CbRuleCreationFailure::OptimizedRulesUnsupported)
let is_complete_regex = v.mask.contains(NetworkFilterMask::IS_COMPLETE_REGEX);

let url_filter = if is_complete_regex {
match (&v.filter, &v.hostname) {
(crate::filters::network::FilterPart::Simple(part), Some(hostname)) => {
if let Some(inner) =
part.strip_prefix('/').and_then(|p| p.strip_suffix('/'))
{
if is_cb_compatible_regex(inner) {
let mut url_filter = format!(
"^[^:]+:(//)?([^/]+\\.)?{}",
SPECIAL_CHARS.replace_all(hostname, r##"\$1"##)
);
if v.mask.contains(NetworkFilterMask::IS_HOSTNAME_REGEX) {
url_filter += ".*";
}
url_filter += inner;
if v.mask.contains(NetworkFilterMask::IS_RIGHT_ANCHOR) {
url_filter += "$";
}
url_filter
} else {
return Err(CbRuleCreationFailure::FullRegexUnsupported);
}
} else {
return Err(CbRuleCreationFailure::FullRegexUnsupported);
}
}
(crate::filters::network::FilterPart::Simple(part), None) => {
if let Some(inner) =
part.strip_prefix('/').and_then(|p| p.strip_suffix('/'))
{
if is_cb_compatible_regex(inner) {
let mut url_filter =
if v.mask.contains(NetworkFilterMask::IS_LEFT_ANCHOR) {
format!("^{inner}")
} else {
let scheme_part = if v.mask.contains(
NetworkFilterMask::FROM_HTTP
| NetworkFilterMask::FROM_HTTPS,
) {
""
} else if v.mask.contains(NetworkFilterMask::FROM_HTTP) {
"^http://.*"
} else if v.mask.contains(NetworkFilterMask::FROM_HTTPS) {
"^https://.*"
} else if v.mask.contains(NetworkFilterMask::FROM_WEBSOCKET)
{
"^wss?://.*"
} else {
unreachable!("Invalid scheme information");
};
format!("{scheme_part}{inner}")
};
if v.mask.contains(NetworkFilterMask::IS_RIGHT_ANCHOR) {
url_filter += "$";
}
url_filter
} else {
return Err(CbRuleCreationFailure::FullRegexUnsupported);
}
} else {
return Err(CbRuleCreationFailure::FullRegexUnsupported);
}
}
_ => return Err(CbRuleCreationFailure::FullRegexUnsupported),
}
(crate::filters::network::FilterPart::Simple(part), Some(hostname)) => {
let without_trailing_separator = TRAILING_SEPARATOR.replace_all(&part, "");
let escaped_special_chars =
SPECIAL_CHARS.replace_all(&without_trailing_separator, r##"\$1"##);
let with_fixed_wildcards =
REPLACE_WILDCARDS.replace_all(&escaped_special_chars, ".*");

let mut url_filter = format!(
"^[^:]+:(//)?([^/]+\\.)?{}",
SPECIAL_CHARS.replace_all(&hostname, r##"\$1"##)
);

if v.mask.contains(NetworkFilterMask::IS_HOSTNAME_REGEX) {
url_filter += ".*";
} else {
match (&v.filter, &v.hostname) {
(crate::filters::network::FilterPart::AnyOf(_), _) => {
return Err(CbRuleCreationFailure::OptimizedRulesUnsupported)
}
(crate::filters::network::FilterPart::Simple(part), Some(hostname)) => {
let without_trailing_separator = TRAILING_SEPARATOR.replace_all(part, "");
let escaped_special_chars =
SPECIAL_CHARS.replace_all(&without_trailing_separator, r##"\$1"##);
let with_fixed_wildcards =
REPLACE_WILDCARDS.replace_all(&escaped_special_chars, ".*");

let mut url_filter = format!(
"^[^:]+:(//)?([^/]+\\.)?{}",
SPECIAL_CHARS.replace_all(hostname, r##"\$1"##)
);

if v.mask.contains(NetworkFilterMask::IS_HOSTNAME_REGEX) {
url_filter += ".*";
}

url_filter += &with_fixed_wildcards;
url_filter += &with_fixed_wildcards;

if v.mask.contains(NetworkFilterMask::IS_RIGHT_ANCHOR) {
url_filter += "$";
}
if v.mask.contains(NetworkFilterMask::IS_RIGHT_ANCHOR) {
url_filter += "$";
}

url_filter
}
(crate::filters::network::FilterPart::Simple(part), None) => {
let without_trailing_separator = TRAILING_SEPARATOR.replace_all(&part, "");
let escaped_special_chars =
SPECIAL_CHARS.replace_all(&without_trailing_separator, r##"\$1"##);
let with_fixed_wildcards =
REPLACE_WILDCARDS.replace_all(&escaped_special_chars, ".*");
let mut url_filter = if v.mask.contains(NetworkFilterMask::IS_LEFT_ANCHOR) {
format!("^{with_fixed_wildcards}")
} else {
let scheme_part = if v
.mask
.contains(NetworkFilterMask::FROM_HTTP | NetworkFilterMask::FROM_HTTPS)
{
""
} else if v.mask.contains(NetworkFilterMask::FROM_HTTP) {
"^http://.*"
} else if v.mask.contains(NetworkFilterMask::FROM_HTTPS) {
"^https://.*"
} else if v.mask.contains(NetworkFilterMask::FROM_WEBSOCKET) {
"^wss?://.*"
url_filter
}
(crate::filters::network::FilterPart::Simple(part), None) => {
let without_trailing_separator = TRAILING_SEPARATOR.replace_all(part, "");
let escaped_special_chars =
SPECIAL_CHARS.replace_all(&without_trailing_separator, r##"\$1"##);
let with_fixed_wildcards =
REPLACE_WILDCARDS.replace_all(&escaped_special_chars, ".*");
let mut url_filter = if v.mask.contains(NetworkFilterMask::IS_LEFT_ANCHOR) {
format!("^{with_fixed_wildcards}")
} else {
unreachable!("Invalid scheme information");
let scheme_part = if v.mask.contains(
NetworkFilterMask::FROM_HTTP | NetworkFilterMask::FROM_HTTPS,
) {
""
} else if v.mask.contains(NetworkFilterMask::FROM_HTTP) {
"^http://.*"
} else if v.mask.contains(NetworkFilterMask::FROM_HTTPS) {
"^https://.*"
} else if v.mask.contains(NetworkFilterMask::FROM_WEBSOCKET) {
"^wss?://.*"
} else {
unreachable!("Invalid scheme information");
};

format!("{scheme_part}{with_fixed_wildcards}")
};

format!("{scheme_part}{with_fixed_wildcards}")
};
if v.mask.contains(NetworkFilterMask::IS_RIGHT_ANCHOR) {
url_filter += "$";
}

if v.mask.contains(NetworkFilterMask::IS_RIGHT_ANCHOR) {
url_filter += "$";
url_filter
}

url_filter
}
(crate::filters::network::FilterPart::Empty, Some(hostname)) => {
let escaped_special_chars = SPECIAL_CHARS.replace_all(&hostname, r##"\$1"##);
format!("^[^:]+:(//)?([^/]+\\.)?{escaped_special_chars}")
}
(crate::filters::network::FilterPart::Empty, None) => if v
.mask
.contains(NetworkFilterMask::FROM_HTTP | NetworkFilterMask::FROM_HTTPS)
{
"^https?://"
} else if v.mask.contains(NetworkFilterMask::FROM_HTTP) {
"^http://"
} else if v.mask.contains(NetworkFilterMask::FROM_HTTPS) {
"^https://"
} else if v.mask.contains(NetworkFilterMask::FROM_WEBSOCKET) {
"^wss?://"
} else {
unreachable!("Invalid scheme information");
(crate::filters::network::FilterPart::Empty, Some(hostname)) => {
let escaped_special_chars = SPECIAL_CHARS.replace_all(hostname, r##"\$1"##);
format!("^[^:]+:(//)?([^/]+\\.)?{escaped_special_chars}")
}
(crate::filters::network::FilterPart::Empty, None) => if v
.mask
.contains(NetworkFilterMask::FROM_HTTP | NetworkFilterMask::FROM_HTTPS)
{
"^https?://"
} else if v.mask.contains(NetworkFilterMask::FROM_HTTP) {
"^http://"
} else if v.mask.contains(NetworkFilterMask::FROM_HTTPS) {
"^https://"
} else if v.mask.contains(NetworkFilterMask::FROM_WEBSOCKET) {
"^wss?://"
} else {
unreachable!("Invalid scheme information");
}
.to_string(),
}
.to_string(),
};

let (if_domain, unless_domain) = if v.opt_domains.is_some()
Expand Down
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