# mod.rs.html -- source
Source to the Rust file `src/header/mod.rs`.
Keywords: rust, rustlang, rust-lang

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    //! Various http headers
    // This is mostly copy of [hyper](https://github.com/hyperium/hyper/tree/master/src/header)

    use std::fmt;
    use std::str::FromStr;

    use bytes::{Bytes, BytesMut};
    use mime::Mime;
    use modhttp::header::GetAll;
    use modhttp::Error as HttpError;
    use percent_encoding;

    pub use modhttp::header::*;

    use error::ParseError;
    use httpmessage::HttpMessage;

    mod common;
    mod shared;
    #[doc(hidden)]
    pub use self::common::*;
    #[doc(hidden)]
    pub use self::shared::*;

    #[doc(hidden)]
    /// A trait for any object that will represent a header field and value.
    pub trait Header
    where
        Self: IntoHeaderValue,
    {
        /// Returns the name of the header field
        fn name() -> HeaderName;

        /// Parse a header
        fn parse<T: HttpMessage>(msg: &T) -> Result<Self, ParseError>;
    }

    #[doc(hidden)]
    /// A trait for any object that can be Converted to a `HeaderValue`
    pub trait IntoHeaderValue: Sized {
        /// The type returned in the event of a conversion error.
        type Error: Into<HttpError>;

        /// Try to convert value to a Header value.
        fn try_into(self) -> Result<HeaderValue, Self::Error>;
    }

    impl IntoHeaderValue for HeaderValue {
        type Error = InvalidHeaderValue;

        #[inline]
        fn try_into(self) -> Result<HeaderValue, Self::Error> {
            Ok(self)
        }
    }

    impl<'a> IntoHeaderValue for &'a str {
        type Error = InvalidHeaderValue;

        #[inline]
        fn try_into(self) -> Result<HeaderValue, Self::Error> {
            self.parse()
        }
    }

    impl<'a> IntoHeaderValue for &'a [u8] {
        type Error = InvalidHeaderValue;

        #[inline]
        fn try_into(self) -> Result<HeaderValue, Self::Error> {
            HeaderValue::from_bytes(self)
        }
    }

    impl IntoHeaderValue for Bytes {
        type Error = InvalidHeaderValueBytes;

        #[inline]
        fn try_into(self) -> Result<HeaderValue, Self::Error> {
            HeaderValue::from_shared(self)
        }
    }

    impl IntoHeaderValue for Vec<u8> {
        type Error = InvalidHeaderValueBytes;

        #[inline]
        fn try_into(self) -> Result<HeaderValue, Self::Error> {
            HeaderValue::from_shared(Bytes::from(self))
        }
    }

    impl IntoHeaderValue for String {
        type Error = InvalidHeaderValueBytes;

        #[inline]
        fn try_into(self) -> Result<HeaderValue, Self::Error> {
            HeaderValue::from_shared(Bytes::from(self))
        }
    }

    impl IntoHeaderValue for Mime {
        type Error = InvalidHeaderValueBytes;

        #[inline]
        fn try_into(self) -> Result<HeaderValue, Self::Error> {
            HeaderValue::from_shared(Bytes::from(format!("{}", self)))
        }
    }

    /// Represents supported types of content encodings
    #[derive(Copy, Clone, PartialEq, Debug)]
    pub enum ContentEncoding {
        /// Automatically select encoding based on encoding negotiation
        Auto,
        /// A format using the Brotli algorithm
        #[cfg(feature = "brotli")]
        Br,
        /// A format using the zlib structure with deflate algorithm
        #[cfg(feature = "flate2")]
        Deflate,
        /// Gzip algorithm
        #[cfg(feature = "flate2")]
        Gzip,
        /// Indicates the identity function (i.e. no compression, nor modification)
        Identity,
    }

    impl ContentEncoding {
        #[inline]
        /// Is the content compressed?
        pub fn is_compression(self) -> bool {
            match self {
                ContentEncoding::Identity | ContentEncoding::Auto => false,
                _ => true,
            }
        }

        #[inline]
        /// Convert content encoding to string
        pub fn as_str(self) -> &'static str {
            match self {
                #[cfg(feature = "brotli")]
                ContentEncoding::Br => "br",
                #[cfg(feature = "flate2")]
                ContentEncoding::Gzip => "gzip",
                #[cfg(feature = "flate2")]
                ContentEncoding::Deflate => "deflate",
                ContentEncoding::Identity | ContentEncoding::Auto => "identity",
            }
        }

        #[inline]
        /// default quality value
        pub fn quality(self) -> f64 {
            match self {
                #[cfg(feature = "brotli")]
                ContentEncoding::Br => 1.1,
                #[cfg(feature = "flate2")]
                ContentEncoding::Gzip => 1.0,
                #[cfg(feature = "flate2")]
                ContentEncoding::Deflate => 0.9,
                ContentEncoding::Identity | ContentEncoding::Auto => 0.1,
            }
        }
    }

    // TODO: remove memory allocation
    impl<'a> From<&'a str> for ContentEncoding {
        fn from(s: &'a str) -> ContentEncoding {
            match AsRef::<str>::as_ref(&s.trim().to_lowercase()) {
                #[cfg(feature = "brotli")]
                "br" => ContentEncoding::Br,
                #[cfg(feature = "flate2")]
                "gzip" => ContentEncoding::Gzip,
                #[cfg(feature = "flate2")]
                "deflate" => ContentEncoding::Deflate,
                _ => ContentEncoding::Identity,
            }
        }
    }

    #[doc(hidden)]
    pub(crate) struct Writer {
        buf: BytesMut,
    }

    impl Writer {
        fn new() -> Writer {
            Writer {
                buf: BytesMut::new(),
            }
        }
        fn take(&mut self) -> Bytes {
            self.buf.take().freeze()
        }
    }

    impl fmt::Write for Writer {
        #[inline]
        fn write_str(&mut self, s: &str) -> fmt::Result {
            self.buf.extend_from_slice(s.as_bytes());
            Ok(())
        }

        #[inline]
        fn write_fmt(&mut self, args: fmt::Arguments) -> fmt::Result {
            fmt::write(self, args)
        }
    }

    #[inline]
    #[doc(hidden)]
    /// Reads a comma-delimited raw header into a Vec.
    pub fn from_comma_delimited<T: FromStr>(
        all: GetAll<HeaderValue>,
    ) -> Result<Vec<T>, ParseError> {
        let mut result = Vec::new();
        for h in all {
            let s = h.to_str().map_err(|_| ParseError::Header)?;
            result.extend(
                s.split(',')
                    .filter_map(|x| match x.trim() {
                        "" => None,
                        y => Some(y),
                    }).filter_map(|x| x.trim().parse().ok()),
            )
        }
        Ok(result)
    }

    #[inline]
    #[doc(hidden)]
    /// Reads a single string when parsing a header.
    pub fn from_one_raw_str<T: FromStr>(val: Option<&HeaderValue>) -> Result<T, ParseError> {
        if let Some(line) = val {
            let line = line.to_str().map_err(|_| ParseError::Header)?;
            if !line.is_empty() {
                return T::from_str(line).or(Err(ParseError::Header));
            }
        }
        Err(ParseError::Header)
    }

    #[inline]
    #[doc(hidden)]
    /// Format an array into a comma-delimited string.
    pub fn fmt_comma_delimited<T>(f: &mut fmt::Formatter, parts: &[T]) -> fmt::Result
    where
        T: fmt::Display,
    {
        let mut iter = parts.iter();
        if let Some(part) = iter.next() {
            fmt::Display::fmt(part, f)?;
        }
        for part in iter {
            f.write_str(", ")?;
            fmt::Display::fmt(part, f)?;
        }
        Ok(())
    }

    // From hyper v0.11.27 src/header/parsing.rs

    /// The value part of an extended parameter consisting of three parts:
    /// the REQUIRED character set name (`charset`), the OPTIONAL language information (`language_tag`),
    /// and a character sequence representing the actual value (`value`), separated by single quote
    /// characters. It is defined in [RFC 5987](https://tools.ietf.org/html/rfc5987#section-3.2).
    #[derive(Clone, Debug, PartialEq)]
    pub struct ExtendedValue {
        /// The character set that is used to encode the `value` to a string.
        pub charset: Charset,
        /// The human language details of the `value`, if available.
        pub language_tag: Option<LanguageTag>,
        /// The parameter value, as expressed in octets.
        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
    ///
    /// ```text
    /// 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, ::error::ParseError> {
        // 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::ParseError::Header),
            Some(n) => FromStr::from_str(n).map_err(|_| ::error::ParseError::Header)?,
        };

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

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

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

    impl fmt::Display for ExtendedValue {
        fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
            let encoded_value = percent_encoding::percent_encode(
                &self.value[..],
                self::percent_encoding_http::HTTP_VALUE,
            );
            if let Some(ref lang) = self.language_tag {
                write!(f, "{}'{}'{}", self.charset, lang, encoded_value)
            } else {
                write!(f, "{}''{}", self.charset, encoded_value)
            }
        }
    }

    /// Percent encode a sequence of bytes with a character set defined in
    /// [https://tools.ietf.org/html/rfc5987#section-3.2][url]
    ///
    /// [url]: https://tools.ietf.org/html/rfc5987#section-3.2
    pub fn http_percent_encode(f: &mut fmt::Formatter, bytes: &[u8]) -> fmt::Result {
        let encoded =
            percent_encoding::percent_encode(bytes, self::percent_encoding_http::HTTP_VALUE);
        fmt::Display::fmt(&encoded, f)
    }
    mod percent_encoding_http {
        use percent_encoding;

        // internal module because macro is hard-coded to make a public item
        // but we don't want to public export this item
        define_encode_set! {
            // This encode set is used for HTTP header values and is defined at
            // https://tools.ietf.org/html/rfc5987#section-3.2
            pub HTTP_VALUE = [percent_encoding::SIMPLE_ENCODE_SET] | {
                ' ', '"', '%', '\'', '(', ')', '*', ',', '/', ':', ';', '<', '-', '>', '?',
                '[', '\\', ']', '{', '}'
            }
        }
    }

    #[cfg(test)]
    mod tests {
        use super::{parse_extended_value, ExtendedValue};
        use header::shared::Charset;
        use language_tags::LanguageTag;

        #[test]
        fn test_parse_extended_value_with_encoding_and_language_tag() {
            let expected_language_tag = "en".parse::<LanguageTag>().unwrap();
            // 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());
        }

        #[test]
        fn test_fmt_extended_value_with_encoding_and_language_tag() {
            let extended_value = ExtendedValue {
                charset: Charset::Iso_8859_1,
                language_tag: Some("en".parse().expect("Could not parse language tag")),
                value: vec![163, b' ', b'r', b'a', b't', b'e', b's'],
            };
            assert_eq!("ISO-8859-1'en'%A3%20rates", format!("{}", extended_value));
        }

        #[test]
        fn test_fmt_extended_value_with_encoding() {
            let extended_value = ExtendedValue {
                charset: Charset::Ext("UTF-8".to_string()),
                language_tag: None,
                value: 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',
                ],
            };
            assert_eq!(
                "UTF-8''%C2%A3%20and%20%E2%82%AC%20rates",
                format!("{}", extended_value)
            );
        }
    }

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