fix(headers): correctly handle repeated headers

HeaderX: a
    HeaderX: b

MUST be interpreted as

    HeaderX: a, b

See: https://www.w3.org/Protocols/rfc2616/rfc2616-sec4.html#sec4.2

Fixes #683

src/header/common/cache_control.rs

@@ -1,7 +1,7 @@
 use std::fmt;
 use std::str::FromStr;
 use header::{Header, HeaderFormat};
-use header::parsing::{from_one_comma_delimited, fmt_comma_delimited};
+use header::parsing::{from_comma_delimited, fmt_comma_delimited};
 
 /// `Cache-Control` header, defined in [RFC7234](https://tools.ietf.org/html/rfc7234#section-5.2)
 ///
@@ -55,10 +55,7 @@ impl Header for CacheControl {
     }
 
     fn parse_header(raw: &[Vec<u8>]) -> ::Result<CacheControl> {
-        let directives = raw.iter()
-            .filter_map(|line| from_one_comma_delimited(&line[..]).ok())
-            .collect::<Vec<Vec<CacheDirective>>>()
-            .concat();
+        let directives = try!(from_comma_delimited(raw));
         if !directives.is_empty() {
             Ok(CacheControl(directives))
         } else {

src/header/common/content_length.rs

@@ -79,7 +79,16 @@ __hyper__tm!(ContentLength, tests {
     test_header!(test1, vec![b"3495"], Some(HeaderField(3495)));
 
     test_header!(test_invalid, vec![b"34v95"], None);
-    test_header!(test_duplicates, vec![b"5", b"5"], Some(HeaderField(5)));
+
+    // Can't use the test_header macro because "5, 5" gets cleaned to "5".
+    #[test]
+    fn test_duplicates() {
+        let parsed = HeaderField::parse_header(&[b"5"[..].into(),
+                                                 b"5"[..].into()]).unwrap();
+        assert_eq!(parsed, HeaderField(5));
+        assert_eq!(format!("{}", parsed), "5");
+    }
+
     test_header!(test_duplicates_vary, vec![b"5", b"6", b"5"], None);
 });
 

src/header/common/mod.rs

@@ -156,8 +156,15 @@ macro_rules! test_header {
             assert_eq!(val.ok(), typed);
             // Test formatting
             if typed.is_some() {
-                let res: &str = str::from_utf8($raw[0]).unwrap();
-                assert_eq!(format!("{}", typed.unwrap()), res);
+                let raw = &($raw)[..];
+                let mut iter = raw.iter().map(|b|str::from_utf8(&b[..]).unwrap());
+                let mut joined = String::new();
+                joined.push_str(iter.next().unwrap());
+                for s in iter {
+                    joined.push_str(", ");
+                    joined.push_str(s);
+                }
+                assert_eq!(format!("{}", typed.unwrap()), joined);
             }
         }
     }

src/header/common/range.rs

@@ -2,7 +2,7 @@ use std::fmt::{self, Display};
 use std::str::FromStr;
 
 use header::{Header, HeaderFormat};
-use header::parsing::{from_one_raw_str, from_one_comma_delimited};
+use header::parsing::{from_one_raw_str, from_comma_delimited};
 
 /// `Range` header, defined in [RFC7233](https://tools.ietf.org/html/rfc7233#section-3.1)
 ///
@@ -130,7 +130,7 @@ impl FromStr for Range {
 
         match (iter.next(), iter.next()) {
             (Some("bytes"), Some(ranges)) => {
-                match from_one_comma_delimited(ranges.as_bytes()) {
+                match from_comma_delimited(&[ranges]) {
                     Ok(ranges) => {
                         if ranges.is_empty() {
                             return Err(::Error::Header);

src/header/common/transfer_encoding.rs

@@ -38,6 +38,13 @@ header! {
             Some(HeaderField(
                 vec![Encoding::Gzip, Encoding::Chunked]
                 )));
+        // Issue: #683
+        test_header!(
+            test2,
+            vec![b"chunked", b"chunked"],
+            Some(HeaderField(
+                vec![Encoding::Chunked, Encoding::Chunked]
+            )));
 
     }
 }