successfully decode q encoding in header

src/fragments/encoding.rs

@@ -8,44 +8,70 @@ use nom::{
     sequence::{preceded, tuple},
     multi::many0,
 };
+use encoding_rs::Encoding;
 
 use crate::fragments::mime;
 
-pub fn encoded_word(input: &str) -> IResult<&str, Cow<str>> {
+pub fn encoded_word(input: &str) -> IResult<&str, String> {
     let (rest, (_, charset, _, enc, _, txt, _)) = tuple((
-        tag("=?"), mime::token, tag("?"), one_of("QBqb"), tag("?"), encoded_text, tag("?=")
+        tag("=?"), mime::token, tag("?"), one_of("QBqb"), tag("?"), ptext, tag("?=")
     ))(input)?;
 
-    match enc {
+    let renc =  Encoding::for_label(charset.as_bytes()).unwrap_or(encoding_rs::WINDOWS_1252);
+
+    let parsed = match enc {
         // quoted printable
-        'q'|'Q' => todo!(),
+        'q'|'Q' => decode_quoted_encoding(renc, txt.iter()),
         // base64
         'b'|'B' => todo!(),
         _ => unreachable!(),
-    }
+    };
+
+    Ok((rest, parsed))
 }
 
-fn encoded_text(input: &str) -> IResult<&str, &str> {
-    take_while1(is_encoded_text)(input)
+fn decode_quoted_encoding<'a>(enc: &'static Encoding, q: impl Iterator<Item = &'a QuotedChunk<'a>>) -> String {
+    q.fold(
+        String::new(), 
+        |mut acc, c| {
+            let dec = match c {
+                QuotedChunk::Safe(v) => Cow::Borrowed(*v),
+                QuotedChunk::Space => Cow::Borrowed(" "),
+                QuotedChunk::Encoded(v) => {
+                    let w = &[*v];
+                    let (d, _, _) = enc.decode(w);
+                    Cow::Owned(d.into_owned())
+                },
+            };
+            acc.push_str(dec.as_ref());
+            acc
+        })
 }
 
-fn is_encoded_text(c: char) -> bool {
-    c.is_ascii() && !c.is_ascii_control() && !c.is_ascii_whitespace()
-}
 
 #[derive(PartialEq,Debug)]
 pub enum QuotedChunk<'a> {
     Safe(&'a str),
     Encoded(u8),
+    Space,
 }
 
 //quoted_printable
 pub fn ptext(input: &str) -> IResult<&str, Vec<QuotedChunk>> {
-    many0(alt((safe_char, hex_octet)))(input)
+    many0(alt((safe_char2, encoded_space, hex_octet)))(input)
 }
 
-fn safe_char(input: &str) -> IResult<&str, QuotedChunk> {
-  map(take_while1(is_safe_char), |v| QuotedChunk::Safe(v))(input)  
+fn safe_char2(input: &str) -> IResult<&str, QuotedChunk> {
+  map(take_while1(is_safe_char2), |v| QuotedChunk::Safe(v))(input)  
+}
+
+
+/// RFC2047 section 4.2
+/// 8-bit values which correspond to printable ASCII characters other
+/// than "=", "?", and "_" (underscore), MAY be represented as those
+/// characters.
+fn is_safe_char2(c: char) -> bool {
+    c.is_ascii() && !c.is_ascii_control() && c != '_' && c != '?' && c != '='
 }
 
 fn is_safe_char(c: char) -> bool {
@@ -53,6 +79,10 @@ fn is_safe_char(c: char) -> bool {
         (c >= '\x3e' && c <= '\x7e')
 }
 
+fn encoded_space(input: &str) -> IResult<&str, QuotedChunk> {
+    map(tag("_"), |_| QuotedChunk::Space)(input)
+}
+
 fn hex_octet(input: &str) -> IResult<&str, QuotedChunk> {
     use nom;
     use nom::error::*;
@@ -80,12 +110,26 @@ mod tests {
             Ok(("", vec![
                 QuotedChunk::Safe("Accus"),
                 QuotedChunk::Encoded(0xe9),
-                QuotedChunk::Safe("_de_r"),
+                QuotedChunk::Space,
+                QuotedChunk::Safe("de"),
+                QuotedChunk::Space,
+                QuotedChunk::Safe("r"),
                 QuotedChunk::Encoded(0xe9),
-                QuotedChunk::Safe("ception_(affich"),
+                QuotedChunk::Safe("ception"),
+                QuotedChunk::Space,
+                QuotedChunk::Safe("(affich"),
                 QuotedChunk::Encoded(0xe9),
                 QuotedChunk::Safe(")"),
             ]))
         );
     }
+
+
+    #[test]
+    fn test_decode_word() {
+        assert_eq!(
+            encoded_word("=?iso8859-1?Q?Accus=E9_de_r=E9ception_(affich=E9)?="),
+            Ok(("", "Accusé de réception (affiché)".into())),
+        );
+    }
 }