Merge actix-http project

actix-http/src/header/shared/entity.rs

@@ -0,0 +1,265 @@
+use std::fmt::{self, Display, Write};
+use std::str::FromStr;
+
+use crate::header::{HeaderValue, IntoHeaderValue, InvalidHeaderValueBytes, Writer};
+
+/// check that each char in the slice is either:
+/// 1. `%x21`, or
+/// 2. in the range `%x23` to `%x7E`, or
+/// 3. above `%x80`
+fn check_slice_validity(slice: &str) -> bool {
+    slice
+        .bytes()
+        .all(|c| c == b'\x21' || (c >= b'\x23' && c <= b'\x7e') | (c >= b'\x80'))
+}
+
+/// An entity tag, defined in [RFC7232](https://tools.ietf.org/html/rfc7232#section-2.3)
+///
+/// An entity tag consists of a string enclosed by two literal double quotes.
+/// Preceding the first double quote is an optional weakness indicator,
+/// which always looks like `W/`. Examples for valid tags are `"xyzzy"` and
+/// `W/"xyzzy"`.
+///
+/// # ABNF
+///
+/// ```text
+/// entity-tag = [ weak ] opaque-tag
+/// weak       = %x57.2F ; "W/", case-sensitive
+/// opaque-tag = DQUOTE *etagc DQUOTE
+/// etagc      = %x21 / %x23-7E / obs-text
+///            ; VCHAR except double quotes, plus obs-text
+/// ```
+///
+/// # Comparison
+/// To check if two entity tags are equivalent in an application always use the
+/// `strong_eq` or `weak_eq` methods based on the context of the Tag. Only use
+/// `==` to check if two tags are identical.
+///
+/// The example below shows the results for a set of entity-tag pairs and
+/// both the weak and strong comparison function results:
+///
+/// | `ETag 1`| `ETag 2`| Strong Comparison | Weak Comparison |
+/// |---------|---------|-------------------|-----------------|
+/// | `W/"1"` | `W/"1"` | no match          | match           |
+/// | `W/"1"` | `W/"2"` | no match          | no match        |
+/// | `W/"1"` | `"1"`   | no match          | match           |
+/// | `"1"`   | `"1"`   | match             | match           |
+#[derive(Clone, Debug, Eq, PartialEq)]
+pub struct EntityTag {
+    /// Weakness indicator for the tag
+    pub weak: bool,
+    /// The opaque string in between the DQUOTEs
+    tag: String,
+}
+
+impl EntityTag {
+    /// Constructs a new EntityTag.
+    /// # Panics
+    /// If the tag contains invalid characters.
+    pub fn new(weak: bool, tag: String) -> EntityTag {
+        assert!(check_slice_validity(&tag), "Invalid tag: {:?}", tag);
+        EntityTag { weak, tag }
+    }
+
+    /// Constructs a new weak EntityTag.
+    /// # Panics
+    /// If the tag contains invalid characters.
+    pub fn weak(tag: String) -> EntityTag {
+        EntityTag::new(true, tag)
+    }
+
+    /// Constructs a new strong EntityTag.
+    /// # Panics
+    /// If the tag contains invalid characters.
+    pub fn strong(tag: String) -> EntityTag {
+        EntityTag::new(false, tag)
+    }
+
+    /// Get the tag.
+    pub fn tag(&self) -> &str {
+        self.tag.as_ref()
+    }
+
+    /// Set the tag.
+    /// # Panics
+    /// If the tag contains invalid characters.
+    pub fn set_tag(&mut self, tag: String) {
+        assert!(check_slice_validity(&tag), "Invalid tag: {:?}", tag);
+        self.tag = tag
+    }
+
+    /// For strong comparison two entity-tags are equivalent if both are not
+    /// weak and their opaque-tags match character-by-character.
+    pub fn strong_eq(&self, other: &EntityTag) -> bool {
+        !self.weak && !other.weak && self.tag == other.tag
+    }
+
+    /// For weak comparison two entity-tags are equivalent if their
+    /// opaque-tags match character-by-character, regardless of either or
+    /// both being tagged as "weak".
+    pub fn weak_eq(&self, other: &EntityTag) -> bool {
+        self.tag == other.tag
+    }
+
+    /// The inverse of `EntityTag.strong_eq()`.
+    pub fn strong_ne(&self, other: &EntityTag) -> bool {
+        !self.strong_eq(other)
+    }
+
+    /// The inverse of `EntityTag.weak_eq()`.
+    pub fn weak_ne(&self, other: &EntityTag) -> bool {
+        !self.weak_eq(other)
+    }
+}
+
+impl Display for EntityTag {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        if self.weak {
+            write!(f, "W/\"{}\"", self.tag)
+        } else {
+            write!(f, "\"{}\"", self.tag)
+        }
+    }
+}
+
+impl FromStr for EntityTag {
+    type Err = crate::error::ParseError;
+
+    fn from_str(s: &str) -> Result<EntityTag, crate::error::ParseError> {
+        let length: usize = s.len();
+        let slice = &s[..];
+        // Early exits if it doesn't terminate in a DQUOTE.
+        if !slice.ends_with('"') || slice.len() < 2 {
+            return Err(crate::error::ParseError::Header);
+        }
+        // The etag is weak if its first char is not a DQUOTE.
+        if slice.len() >= 2
+            && slice.starts_with('"')
+            && check_slice_validity(&slice[1..length - 1])
+        {
+            // No need to check if the last char is a DQUOTE,
+            // we already did that above.
+            return Ok(EntityTag {
+                weak: false,
+                tag: slice[1..length - 1].to_owned(),
+            });
+        } else if slice.len() >= 4
+            && slice.starts_with("W/\"")
+            && check_slice_validity(&slice[3..length - 1])
+        {
+            return Ok(EntityTag {
+                weak: true,
+                tag: slice[3..length - 1].to_owned(),
+            });
+        }
+        Err(crate::error::ParseError::Header)
+    }
+}
+
+impl IntoHeaderValue for EntityTag {
+    type Error = InvalidHeaderValueBytes;
+
+    fn try_into(self) -> Result<HeaderValue, Self::Error> {
+        let mut wrt = Writer::new();
+        write!(wrt, "{}", self).unwrap();
+        HeaderValue::from_shared(wrt.take())
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::EntityTag;
+
+    #[test]
+    fn test_etag_parse_success() {
+        // Expected success
+        assert_eq!(
+            "\"foobar\"".parse::<EntityTag>().unwrap(),
+            EntityTag::strong("foobar".to_owned())
+        );
+        assert_eq!(
+            "\"\"".parse::<EntityTag>().unwrap(),
+            EntityTag::strong("".to_owned())
+        );
+        assert_eq!(
+            "W/\"weaktag\"".parse::<EntityTag>().unwrap(),
+            EntityTag::weak("weaktag".to_owned())
+        );
+        assert_eq!(
+            "W/\"\x65\x62\"".parse::<EntityTag>().unwrap(),
+            EntityTag::weak("\x65\x62".to_owned())
+        );
+        assert_eq!(
+            "W/\"\"".parse::<EntityTag>().unwrap(),
+            EntityTag::weak("".to_owned())
+        );
+    }
+
+    #[test]
+    fn test_etag_parse_failures() {
+        // Expected failures
+        assert!("no-dquotes".parse::<EntityTag>().is_err());
+        assert!("w/\"the-first-w-is-case-sensitive\""
+            .parse::<EntityTag>()
+            .is_err());
+        assert!("".parse::<EntityTag>().is_err());
+        assert!("\"unmatched-dquotes1".parse::<EntityTag>().is_err());
+        assert!("unmatched-dquotes2\"".parse::<EntityTag>().is_err());
+        assert!("matched-\"dquotes\"".parse::<EntityTag>().is_err());
+    }
+
+    #[test]
+    fn test_etag_fmt() {
+        assert_eq!(
+            format!("{}", EntityTag::strong("foobar".to_owned())),
+            "\"foobar\""
+        );
+        assert_eq!(format!("{}", EntityTag::strong("".to_owned())), "\"\"");
+        assert_eq!(
+            format!("{}", EntityTag::weak("weak-etag".to_owned())),
+            "W/\"weak-etag\""
+        );
+        assert_eq!(
+            format!("{}", EntityTag::weak("\u{0065}".to_owned())),
+            "W/\"\x65\""
+        );
+        assert_eq!(format!("{}", EntityTag::weak("".to_owned())), "W/\"\"");
+    }
+
+    #[test]
+    fn test_cmp() {
+        // | ETag 1  | ETag 2  | Strong Comparison | Weak Comparison |
+        // |---------|---------|-------------------|-----------------|
+        // | `W/"1"` | `W/"1"` | no match          | match           |
+        // | `W/"1"` | `W/"2"` | no match          | no match        |
+        // | `W/"1"` | `"1"`   | no match          | match           |
+        // | `"1"`   | `"1"`   | match             | match           |
+        let mut etag1 = EntityTag::weak("1".to_owned());
+        let mut etag2 = EntityTag::weak("1".to_owned());
+        assert!(!etag1.strong_eq(&etag2));
+        assert!(etag1.weak_eq(&etag2));
+        assert!(etag1.strong_ne(&etag2));
+        assert!(!etag1.weak_ne(&etag2));
+
+        etag1 = EntityTag::weak("1".to_owned());
+        etag2 = EntityTag::weak("2".to_owned());
+        assert!(!etag1.strong_eq(&etag2));
+        assert!(!etag1.weak_eq(&etag2));
+        assert!(etag1.strong_ne(&etag2));
+        assert!(etag1.weak_ne(&etag2));
+
+        etag1 = EntityTag::weak("1".to_owned());
+        etag2 = EntityTag::strong("1".to_owned());
+        assert!(!etag1.strong_eq(&etag2));
+        assert!(etag1.weak_eq(&etag2));
+        assert!(etag1.strong_ne(&etag2));
+        assert!(!etag1.weak_ne(&etag2));
+
+        etag1 = EntityTag::strong("1".to_owned());
+        etag2 = EntityTag::strong("1".to_owned());
+        assert!(etag1.strong_eq(&etag2));
+        assert!(etag1.weak_eq(&etag2));
+        assert!(!etag1.strong_ne(&etag2));
+        assert!(!etag1.weak_ne(&etag2));
+    }
+}