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feat(headers): add extended parameter parser to the public API
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Move the extended parameter parser from the Content-Disposition header
implementation into the common header parsing module. This allows crates that
use Hyper to parse RFC 5987-compliant header parameter values.
Add tests based on the examples given in the RFC.
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@malept
malept committed Dec 15, 2015
1 parent 23f20c7 commit 402fb76
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Showing 2 changed files with 136 additions and 65 deletions.
68 changes: 3 additions & 65 deletions src/header/common/content_disposition.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -8,11 +8,11 @@

use language_tags::LanguageTag;
use std::fmt;
use std::str::FromStr;
use unicase::UniCase;
use url::percent_encoding;

use header::{Header, HeaderFormat, parsing};
use header::parsing::parse_extended_value;
use header::shared::Charset;

/// The implied disposition of the content of the HTTP body
Expand Down Expand Up @@ -133,8 +133,8 @@ impl Header for ContentDisposition {
Charset::Ext("UTF-8".to_owned()), None,
val.trim_matches('"').as_bytes().to_owned())
} else if UniCase(&*key) == UniCase("filename*") {
let (charset, opt_language, value) = try!(parse_ext_value(val));
DispositionParam::Filename(charset, opt_language, value)
let extended_value = try!(parse_extended_value(val));
DispositionParam::Filename(extended_value.charset, extended_value.language_tag, extended_value.value)
} else {
DispositionParam::Ext(key.to_owned(), val.trim_matches('"').to_owned())
}
Expand Down Expand Up @@ -195,68 +195,6 @@ impl fmt::Display for ContentDisposition {
}
}

/// Parsing of `ext-value`
/// https://tools.ietf.org/html/rfc5987#section-3.2
///
/// # ABNF
/// ```plain
/// ext-value = charset "'" [ language ] "'" value-chars
/// ; like RFC 2231's <extended-initial-value>
/// ; (see [RFC2231], Section 7)
///
/// charset = "UTF-8" / "ISO-8859-1" / mime-charset
///
/// mime-charset = 1*mime-charsetc
/// mime-charsetc = ALPHA / DIGIT
/// / "!" / "#" / "$" / "%" / "&"
/// / "+" / "-" / "^" / "_" / "`"
/// / "{" / "}" / "~"
/// ; as <mime-charset> in Section 2.3 of [RFC2978]
/// ; except that the single quote is not included
/// ; SHOULD be registered in the IANA charset registry
///
/// language = <Language-Tag, defined in [RFC5646], Section 2.1>
///
/// value-chars = *( pct-encoded / attr-char )
///
/// pct-encoded = "%" HEXDIG HEXDIG
/// ; see [RFC3986], Section 2.1
///
/// attr-char = ALPHA / DIGIT
/// / "!" / "#" / "$" / "&" / "+" / "-" / "."
/// / "^" / "_" / "`" / "|" / "~"
/// ; token except ( "*" / "'" / "%" )
/// ```
fn parse_ext_value(val: &str) -> ::Result<(Charset, Option<LanguageTag>, Vec<u8>)> {

// Break into three pieces separated by the single-quote character
let mut parts = val.splitn(3,'\'');

// Interpret the first piece as a Charset
let charset: Charset = match parts.next() {
None => return Err(::Error::Header),
Some(n) => try!(FromStr::from_str(n)),
};

// Interpret the second piece as a language tag
let lang: Option<LanguageTag> = match parts.next() {
None => return Err(::Error::Header),
Some("") => None,
Some(s) => match s.parse() {
Ok(lt) => Some(lt),
Err(_) => return Err(::Error::Header),
}
};

// Interpret the third piece as a sequence of value characters
let value: Vec<u8> = match parts.next() {
None => return Err(::Error::Header),
Some(v) => percent_encoding::percent_decode(v.as_bytes()),
};

Ok( (charset, lang, value) )
}

#[cfg(test)]
mod tests {
use super::{ContentDisposition,DispositionType,DispositionParam};
Expand Down
133 changes: 133 additions & 0 deletions src/header/parsing.rs
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Original file line number Diff line number Diff line change
@@ -1,7 +1,12 @@
//! Utility functions for Header implementations.
use language_tags::LanguageTag;
use std::str;
use std::str::FromStr;
use std::fmt::{self, Display};
use url::percent_encoding;

use header::shared::Charset;

/// Reads a single raw string when parsing a header.
pub fn from_one_raw_str<T: str::FromStr>(raw: &[Vec<u8>]) -> ::Result<T> {
Expand Down Expand Up @@ -48,3 +53,131 @@ pub fn fmt_comma_delimited<T: Display>(f: &mut fmt::Formatter, parts: &[T]) -> f
}
Ok(())
}

/// An extended header parameter value (i.e., tagged with a character set and optionally,
/// a language), as defined in [RFC 5987](https://tools.ietf.org/html/rfc5987#section-3.2).
pub struct ExtendedValue {
pub charset: Charset,
pub language_tag: Option<LanguageTag>,
pub value: Vec<u8>,
}

/// Parses extended header parameter values (`ext-value`), as defined in
/// [RFC 5987](https://tools.ietf.org/html/rfc5987#section-3.2).
///
/// Extended values are denoted by parameter names that end with `*`.
///
/// ## ABNF
/// ```plain
/// ext-value = charset "'" [ language ] "'" value-chars
/// ; like RFC 2231's <extended-initial-value>
/// ; (see [RFC2231], Section 7)
///
/// charset = "UTF-8" / "ISO-8859-1" / mime-charset
///
/// mime-charset = 1*mime-charsetc
/// mime-charsetc = ALPHA / DIGIT
/// / "!" / "#" / "$" / "%" / "&"
/// / "+" / "-" / "^" / "_" / "`"
/// / "{" / "}" / "~"
/// ; as <mime-charset> in Section 2.3 of [RFC2978]
/// ; except that the single quote is not included
/// ; SHOULD be registered in the IANA charset registry
///
/// language = <Language-Tag, defined in [RFC5646], Section 2.1>
///
/// value-chars = *( pct-encoded / attr-char )
///
/// pct-encoded = "%" HEXDIG HEXDIG
/// ; see [RFC3986], Section 2.1
///
/// attr-char = ALPHA / DIGIT
/// / "!" / "#" / "$" / "&" / "+" / "-" / "."
/// / "^" / "_" / "`" / "|" / "~"
/// ; token except ( "*" / "'" / "%" )
/// ```
pub fn parse_extended_value(val: &str) -> ::Result<ExtendedValue> {

// Break into three pieces separated by the single-quote character
let mut parts = val.splitn(3,'\'');

// Interpret the first piece as a Charset
let charset: Charset = match parts.next() {
None => return Err(::Error::Header),
Some(n) => try!(FromStr::from_str(n)),
};

// Interpret the second piece as a language tag
let lang: Option<LanguageTag> = match parts.next() {
None => return Err(::Error::Header),
Some("") => None,
Some(s) => match s.parse() {
Ok(lt) => Some(lt),
Err(_) => return Err(::Error::Header),
}
};

// Interpret the third piece as a sequence of value characters
let value: Vec<u8> = match parts.next() {
None => return Err(::Error::Header),
Some(v) => percent_encoding::percent_decode(v.as_bytes()),
};

Ok(ExtendedValue {
charset: charset,
language_tag: lang,
value: value,
})
}

#[cfg(test)]
mod tests {
use header::shared::Charset;
use super::parse_extended_value;

#[test]
fn test_parse_extended_value_with_encoding_and_language_tag() {
let expected_language_tag = langtag!(en);
// RFC 5987, Section 3.2.2
// Extended notation, using the Unicode character U+00A3 (POUND SIGN)
let result = parse_extended_value("iso-8859-1'en'%A3%20rates");
assert!(result.is_ok());
let extended_value = result.unwrap();
assert_eq!(Charset::Iso_8859_1, extended_value.charset);
assert!(extended_value.language_tag.is_some());
assert_eq!(expected_language_tag, extended_value.language_tag.unwrap());
assert_eq!(vec![163, b' ', b'r', b'a', b't', b'e', b's'], extended_value.value);
}

#[test]
fn test_parse_extended_value_with_encoding() {
// RFC 5987, Section 3.2.2
// Extended notation, using the Unicode characters U+00A3 (POUND SIGN)
// and U+20AC (EURO SIGN)
let result = parse_extended_value("UTF-8''%c2%a3%20and%20%e2%82%ac%20rates");
assert!(result.is_ok());
let extended_value = result.unwrap();
assert_eq!(Charset::Ext("UTF-8".to_string()), extended_value.charset);
assert!(extended_value.language_tag.is_none());
assert_eq!(vec![194, 163, b' ', b'a', b'n', b'd', b' ', 226, 130, 172, b' ', b'r', b'a', b't', b'e', b's'], extended_value.value);
}

#[test]
fn test_parse_extended_value_missing_language_tag_and_encoding() {
// From: https://greenbytes.de/tech/tc2231/#attwithfn2231quot2
let result = parse_extended_value("foo%20bar.html");
assert!(result.is_err());
}

#[test]
fn test_parse_extended_value_partially_formatted() {
let result = parse_extended_value("UTF-8'missing third part");
assert!(result.is_err());
}

#[test]
fn test_parse_extended_value_partially_formatted_blank() {
let result = parse_extended_value("blank second part'");
assert!(result.is_err());
}
}

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