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Merge pull request #409 from pyfisch/entitytag
feat(entitytag): Add EntityTag comparison, make EntityTag safe to use
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,145 +1,207 @@ | ||
| use std::str::FromStr; | ||
| use std::fmt::{self, Display}; | ||
|
|
||
| /// An entity tag | ||
| // check that each char in the slice is either: | ||
| // 1. %x21, or | ||
| // 2. in the range %x23 to %x7E, or | ||
| // 3. in the range %x80 to %xFF | ||
| fn check_slice_validity(slice: &str) -> bool { | ||
| for c in slice.bytes() { | ||
| match c { | ||
| b'\x21' | b'\x23' ... b'\x7e' | b'\x80' ... b'\xff' => (), | ||
| _ => { return false; } | ||
| } | ||
| } | ||
| true | ||
| } | ||
|
|
||
| /// An entity tag, defined in [RFC7232](https://tools.ietf.org/html/rfc7232#section-2.3) | ||
| /// | ||
| /// An Etag consists of a string enclosed by two literal double quotes. | ||
| /// 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 this: W/ | ||
| /// See also: https://tools.ietf.org/html/rfc7232#section-2.3 | ||
| #[derive(Clone, PartialEq, Debug)] | ||
| /// which always looks like `W/`. Examples for valid tags are `"xyzzy"` and `W/"xyzzy"`. | ||
| /// | ||
| /// # ABNF | ||
| /// ```plain | ||
| /// 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 | ||
| pub tag: String | ||
| tag: String | ||
| } | ||
|
|
||
| impl Display for EntityTag { | ||
| fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result { | ||
| if self.weak { | ||
| try!(write!(fmt, "{}", "W/")); | ||
| impl EntityTag { | ||
| /// Constructs a new EntityTag. | ||
| /// # Panics | ||
| /// If the tag contains invalid characters. | ||
| pub fn new(weak: bool, tag: String) -> EntityTag { | ||
| match check_slice_validity(&tag) { | ||
| true => EntityTag { weak: weak, tag: tag }, | ||
| false => panic!("Invalid tag: {:?}", tag), | ||
| } | ||
| write!(fmt, "{}", self.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) { | ||
| match check_slice_validity(&tag[..]) { | ||
| true => self.tag = tag, | ||
| false => panic!("Invalid 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 == false && other.weak == false && 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) | ||
| } | ||
| } | ||
|
|
||
| // check that each char in the slice is either: | ||
| // 1. %x21, or | ||
| // 2. in the range %x23 to %x7E, or | ||
| // 3. in the range %x80 to %xFF | ||
| fn check_slice_validity(slice: &str) -> bool { | ||
| for c in slice.bytes() { | ||
| match c { | ||
| b'\x21' | b'\x23' ... b'\x7e' | b'\x80' ... b'\xff' => (), | ||
| _ => { return false; } | ||
| impl Display for EntityTag { | ||
| fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result { | ||
| match self.weak { | ||
| true => write!(fmt, "W/\"{}\"", self.tag), | ||
| false => write!(fmt, "\"{}\"", self.tag), | ||
| } | ||
| } | ||
| true | ||
| } | ||
|
|
||
| impl FromStr for EntityTag { | ||
| type Err = (); | ||
| fn from_str(s: &str) -> Result<EntityTag, ()> { | ||
| let length: usize = s.len(); | ||
| let slice = &s[..]; | ||
|
|
||
| // Early exits: | ||
| // 1. The string is empty, or, | ||
| // 2. it doesn't terminate in a DQUOTE. | ||
| if slice.is_empty() || !slice.ends_with('"') { | ||
| return Err(()); | ||
| } | ||
|
|
||
| // The etag is weak if its first char is not a DQUOTE. | ||
| if slice.starts_with('"') /* '"' */ { | ||
| if 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. | ||
| if check_slice_validity(&slice[1..length-1]) { | ||
| return Ok(EntityTag { | ||
| weak: false, | ||
| tag: slice[1..length-1].to_string() | ||
| }); | ||
| } else { | ||
| return Err(()); | ||
| } | ||
| } | ||
|
|
||
| if slice.starts_with("W/\"") { | ||
| if check_slice_validity(&slice[3..length-1]) { | ||
| return Ok(EntityTag { | ||
| weak: true, | ||
| tag: slice[3..length-1].to_string() | ||
| }); | ||
| } else { | ||
| return Err(()); | ||
| } | ||
| return Ok(EntityTag { weak: false, tag: slice[1..length-1].to_string() }); | ||
| } else if slice.starts_with("W/\"") && check_slice_validity(&slice[3..length-1]) { | ||
| return Ok(EntityTag { weak: true, tag: slice[3..length-1].to_string() }); | ||
| } | ||
|
|
||
| Err(()) | ||
| } | ||
| } | ||
|
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||
|
|
||
| #[cfg(test)] | ||
| mod tests { | ||
| use super::EntityTag; | ||
|
|
||
| #[test] | ||
| fn test_etag_successes() { | ||
| // Expected successes | ||
| let mut etag : EntityTag = "\"foobar\"".parse().unwrap(); | ||
| assert_eq!(etag, (EntityTag { | ||
| weak: false, | ||
| tag: "foobar".to_string() | ||
| })); | ||
|
|
||
| etag = "\"\"".parse().unwrap(); | ||
| assert_eq!(etag, EntityTag { | ||
| weak: false, | ||
| tag: "".to_string() | ||
| }); | ||
|
|
||
| etag = "W/\"weak-etag\"".parse().unwrap(); | ||
| assert_eq!(etag, EntityTag { | ||
| weak: true, | ||
| tag: "weak-etag".to_string() | ||
| }); | ||
|
|
||
| etag = "W/\"\x65\x62\"".parse().unwrap(); | ||
| assert_eq!(etag, EntityTag { | ||
| weak: true, | ||
| tag: "\u{0065}\u{0062}".to_string() | ||
| }); | ||
|
|
||
| etag = "W/\"\"".parse().unwrap(); | ||
| assert_eq!(etag, EntityTag { | ||
| weak: true, | ||
| tag: "".to_string() | ||
| }); | ||
| fn test_etag_parse_success() { | ||
| // Expected success | ||
| assert_eq!("\"foobar\"".parse().unwrap(), EntityTag::new(false, "foobar".to_string())); | ||
| assert_eq!("\"\"".parse().unwrap(), EntityTag::new(false, "".to_string())); | ||
| assert_eq!("W/\"weaktag\"".parse().unwrap(), EntityTag::new(true, "weaktag".to_string())); | ||
| assert_eq!("W/\"\x65\x62\"".parse().unwrap(), EntityTag::new(true, "\x65\x62".to_string())); | ||
| assert_eq!("W/\"\"".parse().unwrap(), EntityTag::new(true, "".to_string())); | ||
| } | ||
|
|
||
| #[test] | ||
| fn test_etag_failures() { | ||
| fn test_etag_parse_failures() { | ||
| // Expected failures | ||
| let mut etag: Result<EntityTag,()>; | ||
|
|
||
| etag = "no-dquotes".parse(); | ||
| assert_eq!(etag, Err(())); | ||
|
|
||
| etag = "w/\"the-first-w-is-case-sensitive\"".parse(); | ||
| assert_eq!(etag, Err(())); | ||
|
|
||
| etag = "".parse(); | ||
| assert_eq!(etag, Err(())); | ||
|
|
||
| etag = "\"unmatched-dquotes1".parse(); | ||
| assert_eq!(etag, Err(())); | ||
| assert_eq!("no-dquotes".parse::<EntityTag>(), Err(())); | ||
| assert_eq!("w/\"the-first-w-is-case-sensitive\"".parse::<EntityTag>(), Err(())); | ||
| assert_eq!("".parse::<EntityTag>(), Err(())); | ||
| assert_eq!("\"unmatched-dquotes1".parse::<EntityTag>(), Err(())); | ||
| assert_eq!("unmatched-dquotes2\"".parse::<EntityTag>(), Err(())); | ||
| assert_eq!("matched-\"dquotes\"".parse::<EntityTag>(), Err(())); | ||
| } | ||
|
|
||
| etag = "unmatched-dquotes2\"".parse(); | ||
| assert_eq!(etag, Err(())); | ||
| #[test] | ||
| fn test_etag_fmt() { | ||
| assert_eq!(format!("{}", EntityTag::new(false, "foobar".to_string())), "\"foobar\""); | ||
| assert_eq!(format!("{}", EntityTag::new(false, "".to_string())), "\"\""); | ||
| assert_eq!(format!("{}", EntityTag::new(true, "weak-etag".to_string())), "W/\"weak-etag\""); | ||
| assert_eq!(format!("{}", EntityTag::new(true, "\u{0065}".to_string())), "W/\"\x65\""); | ||
| assert_eq!(format!("{}", EntityTag::new(true, "".to_string())), "W/\"\""); | ||
| } | ||
|
|
||
| etag = "matched-\"dquotes\"".parse(); | ||
| assert_eq!(etag, Err(())); | ||
| #[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::new(true, "1".to_string()); | ||
| let mut etag2 = EntityTag::new(true, "1".to_string()); | ||
| assert_eq!(etag1.strong_eq(&etag2), false); | ||
| assert_eq!(etag1.weak_eq(&etag2), true); | ||
| assert_eq!(etag1.strong_ne(&etag2), true); | ||
| assert_eq!(etag1.weak_ne(&etag2), false); | ||
|
|
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| etag1 = EntityTag::new(true, "1".to_string()); | ||
| etag2 = EntityTag::new(true, "2".to_string()); | ||
| assert_eq!(etag1.strong_eq(&etag2), false); | ||
| assert_eq!(etag1.weak_eq(&etag2), false); | ||
| assert_eq!(etag1.strong_ne(&etag2), true); | ||
| assert_eq!(etag1.weak_ne(&etag2), true); | ||
|
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| etag1 = EntityTag::new(true, "1".to_string()); | ||
| etag2 = EntityTag::new(false, "1".to_string()); | ||
| assert_eq!(etag1.strong_eq(&etag2), false); | ||
| assert_eq!(etag1.weak_eq(&etag2), true); | ||
| assert_eq!(etag1.strong_ne(&etag2), true); | ||
| assert_eq!(etag1.weak_ne(&etag2), false); | ||
|
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| etag1 = EntityTag::new(false, "1".to_string()); | ||
| etag2 = EntityTag::new(false, "1".to_string()); | ||
| assert_eq!(etag1.strong_eq(&etag2), true); | ||
| assert_eq!(etag1.weak_eq(&etag2), true); | ||
| assert_eq!(etag1.strong_ne(&etag2), false); | ||
| assert_eq!(etag1.weak_ne(&etag2), false); | ||
| } | ||
| } |