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|
//! Recognize top-level JSON error markers without buffering response values.
//! This classifies provider error documents; it does not validate arbitrary JSON.
#[derive(Default)]
pub(super) struct ErrorDocument {
started: bool,
finished: bool,
depth: usize,
string: bool,
escaped: bool,
expect_key: bool,
key: Option<Vec<u8>>,
error_key: bool,
value: Option<ErrorValue>,
detected: bool,
}
enum ErrorValue {
Start,
String,
Container(u8),
Literal(Vec<u8>),
}
impl ErrorDocument {
pub fn feed(&mut self, bytes: &[u8]) {
for &byte in bytes {
if self.finished || self.detected {
break;
}
if !self.started {
// JSON producers sometimes include a UTF-8 BOM.
if byte.is_ascii_whitespace() || matches!(byte, 0xef | 0xbb | 0xbf) {
continue;
}
self.started = true;
if byte != b'{' {
self.finished = true;
continue;
}
self.depth = 1;
self.expect_key = true;
continue;
}
self.inspect_value(byte);
if self.detected {
break;
}
if self.string {
if let Some(key) = &mut self.key {
if key.len() < 64 {
key.push(byte);
} else {
self.key = None;
}
}
if self.escaped {
self.escaped = false;
continue;
}
if byte == b'\\' {
self.escaped = true;
continue;
}
if byte == b'"' {
self.string = false;
if let Some(key) = self.key.take() {
self.error_key =
serde_json::from_slice::<String>(&key)
.ok()
.is_some_and(|key| {
key.eq_ignore_ascii_case("error")
|| key.eq_ignore_ascii_case("errors")
});
self.expect_key = false;
}
}
continue;
}
match byte {
b'"' => {
self.string = true;
if self.depth == 1 && self.expect_key {
self.key = Some(vec![b'"']);
}
}
b'{' | b'[' => self.depth = self.depth.saturating_add(1),
b'}' | b']' => {
self.depth = self.depth.saturating_sub(1);
if self.depth == 0 {
self.finished = true;
}
}
b':' if self.depth == 1 && self.error_key => {
self.value = Some(ErrorValue::Start);
self.error_key = false;
}
b',' if self.depth == 1 => {
self.expect_key = true;
self.error_key = false;
}
_ => {}
}
}
}
fn inspect_value(&mut self, byte: u8) {
let Some(value) = self.value.take() else {
return;
};
self.value = match value {
ErrorValue::Start if byte.is_ascii_whitespace() => Some(ErrorValue::Start),
ErrorValue::Start => match byte {
b'"' => Some(ErrorValue::String),
b'[' => Some(ErrorValue::Container(b']')),
b'{' => Some(ErrorValue::Container(b'}')),
b'n' | b'f' | b'0' | b'-' => Some(ErrorValue::Literal(vec![byte])),
_ => {
self.detected = true;
None
}
},
ErrorValue::String => {
self.detected = byte != b'"';
None
}
ErrorValue::Container(end) if byte.is_ascii_whitespace() => {
Some(ErrorValue::Container(end))
}
ErrorValue::Container(end) => {
self.detected = byte != end;
None
}
ErrorValue::Literal(mut bytes) => {
if byte.is_ascii_whitespace() || matches!(byte, b',' | b'}') {
self.detected = literal_is_error(&bytes);
None
} else if bytes.len() < 64 {
bytes.push(byte);
Some(ErrorValue::Literal(bytes))
} else {
self.detected = true;
None
}
}
};
}
pub fn is_error(&self) -> bool {
self.detected
|| match &self.value {
Some(ErrorValue::Literal(bytes)) => literal_is_error(bytes),
// An incomplete value of a declared error field is not a successful download.
Some(_) => true,
None => false,
}
}
pub fn confirmed_error(&self) -> bool {
self.detected
}
}
fn literal_is_error(bytes: &[u8]) -> bool {
match serde_json::from_slice::<serde_json::Value>(bytes) {
Ok(serde_json::Value::Null | serde_json::Value::Bool(false)) => false,
Ok(serde_json::Value::Number(number)) => number.as_f64() != Some(0.0),
_ => true,
}
}
|
