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use crate::headers::{HeaderName, HeaderValue, Headers, ToHeaderValues, ETAG};
use crate::{Error, StatusCode};
use std::fmt::{self, Debug, Display};
use std::option;
#[derive(Debug, Clone, Eq, PartialEq)]
pub enum ETag {
Strong(String),
Weak(String),
}
impl ETag {
pub fn new(s: String) -> Self {
debug_assert!(!s.contains('\\'), "ETags ought to avoid backslash chars");
Self::Strong(s)
}
pub fn new_weak(s: String) -> Self {
debug_assert!(!s.contains('\\'), "ETags ought to avoid backslash chars");
Self::Weak(s)
}
pub fn from_headers(headers: impl AsRef<Headers>) -> crate::Result<Option<Self>> {
let headers = match headers.as_ref().get(ETAG) {
Some(headers) => headers,
None => return Ok(None),
};
let s = headers.iter().last().unwrap().as_str();
Self::from_str(s).map(Some)
}
pub fn apply(&self, mut headers: impl AsMut<Headers>) {
headers.as_mut().insert(ETAG, self.value());
}
pub fn name(&self) -> HeaderName {
ETAG
}
pub fn value(&self) -> HeaderValue {
let s = self.to_string();
unsafe { HeaderValue::from_bytes_unchecked(s.into()) }
}
pub fn is_strong(&self) -> bool {
matches!(self, Self::Strong(_))
}
pub fn is_weak(&self) -> bool {
matches!(self, Self::Weak(_))
}
pub(crate) fn from_str(s: &str) -> crate::Result<Self> {
let mut weak = false;
let s = match s.strip_prefix("W/") {
Some(s) => {
weak = true;
s
}
None => s,
};
let s = match s.strip_prefix('"').and_then(|s| s.strip_suffix('"')) {
Some(s) => s.to_owned(),
None => {
return Err(Error::from_str(
StatusCode::BadRequest,
"Invalid ETag header",
))
}
};
if !s
.bytes()
.all(|c| c == 0x21 || (c >= 0x23 && c <= 0x7E) || c >= 0x80)
{
return Err(Error::from_str(
StatusCode::BadRequest,
"Invalid ETag header",
));
}
let etag = if weak { Self::Weak(s) } else { Self::Strong(s) };
Ok(etag)
}
}
impl Display for ETag {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
Self::Strong(s) => write!(f, r#""{}""#, s),
Self::Weak(s) => write!(f, r#"W/"{}""#, s),
}
}
}
impl ToHeaderValues for ETag {
type Iter = option::IntoIter<HeaderValue>;
fn to_header_values(&self) -> crate::Result<Self::Iter> {
Ok(self.value().to_header_values().unwrap())
}
}
#[cfg(test)]
mod test {
use super::*;
use crate::headers::Headers;
#[test]
fn smoke() -> crate::Result<()> {
let etag = ETag::new("0xcafebeef".to_string());
let mut headers = Headers::new();
etag.apply(&mut headers);
let etag = ETag::from_headers(headers)?.unwrap();
assert_eq!(etag, ETag::Strong(String::from("0xcafebeef")));
Ok(())
}
#[test]
fn smoke_weak() -> crate::Result<()> {
let etag = ETag::new_weak("0xcafebeef".to_string());
let mut headers = Headers::new();
etag.apply(&mut headers);
let etag = ETag::from_headers(headers)?.unwrap();
assert_eq!(etag, ETag::Weak(String::from("0xcafebeef")));
Ok(())
}
#[test]
fn bad_request_on_parse_error() -> crate::Result<()> {
let mut headers = Headers::new();
headers.insert(ETAG, "<nori ate the tag. yum.>");
let err = ETag::from_headers(headers).unwrap_err();
assert_eq!(err.status(), 400);
Ok(())
}
#[test]
fn validate_quotes() -> crate::Result<()> {
assert_entry_err(r#""hello"#, "Invalid ETag header");
assert_entry_err(r#"hello""#, "Invalid ETag header");
assert_entry_err(r#"/O"valid content""#, "Invalid ETag header");
assert_entry_err(r#"/Wvalid content""#, "Invalid ETag header");
Ok(())
}
fn assert_entry_err(s: &str, msg: &str) {
let mut headers = Headers::new();
headers.insert(ETAG, s);
let err = ETag::from_headers(headers).unwrap_err();
assert_eq!(format!("{}", err), msg);
}
#[test]
fn validate_characters() -> crate::Result<()> {
assert_entry_err(r#"""hello""#, "Invalid ETag header");
assert_entry_err("\"hello\x7F\"", "Invalid ETag header");
Ok(())
}
}