s3-headers-lite 0.1.0

/// Given a list of headers, returns headers that match the AWS spec. This includes:
/// - Lowercasing all keys.
/// - Removing all headers that don't start with "x-amz-" or are "host", "content-type", or "range".
/// - Sorting the headers by key.
/// - Trimming whitespace from values.
///
/// # Examples
///
/// ```
/// use s3_headers_lite::aws_canonical::to_canonical_headers;
///
/// let headers = vec![
///  ("Host", "examplebucket.s3.amazonaws.com"),
///  ("Range", "bytes=0-9"),
///  ("x-amz-date", "20130524T000000Z"),
///  ("x-amz-storage-class", "REDUCED_REDUNDANCY"),
/// ];
/// let canonical_headers = to_canonical_headers(&headers);
/// assert_eq!(
///  canonical_headers,
///  vec![
///   ("host".to_owned(), "examplebucket.s3.amazonaws.com"),
///   ("range".to_owned(), "bytes=0-9"),
///   ("x-amz-date".to_owned(), "20130524T000000Z"),
///   ("x-amz-storage-class".to_owned(), "REDUCED_REDUNDANCY"),
///  ]
/// );
/// ```
///
pub fn to_canonical_headers<K: AsRef<str>, V: AsRef<str>>(
    headers: &[(K, V)],
) -> Vec<(std::string::String, &str)> {
    let mut canonical_headers = headers
        .iter()
        .filter_map(|(k, v)| {
            let key = k.as_ref().to_lowercase();
            if key.starts_with("x-amz-") || key == "host" || key == "content-type" || key == "range"
            {
                Some((key, v.as_ref().trim()))
            } else {
                None
            }
        })
        .collect::<Vec<(String, &str)>>();
    canonical_headers.sort();
    canonical_headers
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn to_canonical_headers_lowercases() {
        let headers = vec![
            ("Host", "examplebucket.s3.amazonaws.com"),
            ("Range", "bytes=0-9"),
            ("x-amz-date", "20130524T000000Z"),
            ("x-amz-storage-class", "REDUCED_REDUNDANCY"),
        ];
        let canonical_headers = to_canonical_headers(&headers);
        assert_eq!(
            canonical_headers,
            vec![
                ("host".to_owned(), "examplebucket.s3.amazonaws.com"),
                ("range".to_owned(), "bytes=0-9"),
                ("x-amz-date".to_owned(), "20130524T000000Z"),
                ("x-amz-storage-class".to_owned(), "REDUCED_REDUNDANCY"),
            ],
        );
    }

    #[test]
    fn test_to_canonical_headers_lowercases_removes_sorts() {
        // Should sort by key.
        let headers = &[
            ("x-amz-special", "a"),
            // Should lowercase this.
            ("Host", "s3.etc"),
            ("x-amz-storage-class", "REDUCED_REDUNDANCY"),
            ("content-Type", "application/json"),
            ("x-amz-date", "19700101T000000Z"),
            // Should remove this.
            ("foo", "bar"),
        ];

        let result = to_canonical_headers(headers);

        assert_eq!(
            result,
            vec![
                ("content-type".to_owned(), "application/json"),
                ("host".to_owned(), "s3.etc"),
                ("x-amz-date".to_owned(), "19700101T000000Z"),
                ("x-amz-special".to_owned(), "a"),
                ("x-amz-storage-class".to_owned(), "REDUCED_REDUNDANCY"),
            ],
        )
    }

    #[test]
    fn test_to_canonical_headers_accepts_ref_array_string_string() {
        let headers = &[
            ("Host".to_string(), "s3.etc".to_string()),
            (
                "x-amz-storage-class".to_string(),
                "REDUCED_REDUNDANCY".to_string(),
            ),
            ("content-Type".to_string(), "application/json".to_string()),
        ];

        let result = to_canonical_headers(headers);

        assert_eq!(
            result,
            vec![
                ("content-type".to_owned(), "application/json"),
                ("host".to_owned(), "s3.etc"),
                ("x-amz-storage-class".to_owned(), "REDUCED_REDUNDANCY"),
            ],
        )
    }

    #[test]
    fn test_to_canonical_headers_accepts_ref_vec_string_string() {
        let headers = vec![
            ("Host".to_string(), "s3.etc".to_string()),
            (
                "x-amz-storage-class".to_string(),
                "REDUCED_REDUNDANCY".to_string(),
            ),
            ("content-Type".to_string(), "application/json".to_string()),
        ];

        let result = to_canonical_headers(&headers);

        assert_eq!(
            result,
            vec![
                ("content-type".to_owned(), "application/json"),
                ("host".to_owned(), "s3.etc"),
                ("x-amz-storage-class".to_owned(), "REDUCED_REDUNDANCY"),
            ],
        )
    }

    #[test]
    fn test_to_canonical_headers_accepts_borrows() {
        let borrow1 = "s3.etc";
        let borrow2 = "x-amz-storage-class";
        let headers = &[
            ("Host", borrow1),
            (borrow2, "REDUCED_REDUNDANCY"),
            ("content-Type", "application/json"),
        ];

        let result = to_canonical_headers(headers);

        assert_eq!(
            result,
            vec![
                ("content-type".to_owned(), "application/json"),
                ("host".to_owned(), borrow1),
                ("x-amz-storage-class".to_owned(), "REDUCED_REDUNDANCY"),
            ],
        )
    }
}