wip encoding

src/fragments/encoding.rs

@@ -0,0 +1,85 @@
+use std::borrow::Cow;
+use nom::{
+    IResult,
+    branch::alt,
+    bytes::complete::{tag, take_while1},
+    character::complete::{hex_digit1, one_of},
+    combinator::map,
+    sequence::{preceded, tuple},
+    multi::many0,
+};
+
+use crate::fragments::mime;
+
+pub fn encoded_word(input: &str) -> IResult<&str, Cow<str>> {
+    let (rest, (_, charset, _, enc, _, txt, _)) = tuple((
+        tag("=?"), mime::token, tag("?"), one_of("QBqb"), tag("?"), encoded_text, tag("?=")
+    ))(input)?;
+
+    match enc {
+        // quoted printable
+        'q'|'Q' => todo!(),
+        // base64
+        'b'|'B' => todo!(),
+        _ => unreachable!(),
+    }
+}
+
+fn encoded_text(input: &str) -> IResult<&str, &str> {
+    take_while1(is_encoded_text)(input)
+}
+
+fn is_encoded_text(c: char) -> bool {
+    c.is_ascii() && !c.is_ascii_control() && !c.is_ascii_whitespace()
+}
+
+pub enum QuotedChunk<'a> {
+    Safe(&'a str),
+    Encoded(u8),
+}
+
+//quoted_printable
+pub fn ptext(input: &str) -> IResult<&str, Vec<QuotedChunk>> {
+    many0(alt((safe_char, hex_octet)))(input)
+}
+
+fn safe_char(input: &str) -> IResult<&str, QuotedChunk> {
+  map(take_while1(is_safe_char), |v| QuotedChunk::Safe(v))(input)  
+}
+
+fn is_safe_char(c: char) -> bool {
+    (c >= '\x21' && c <= '\x3c') ||
+        (c >= '\x3e' && c <= '\x7e')
+}
+
+fn hex_octet(input: &str) -> IResult<&str, QuotedChunk> {
+    use nom;
+    use nom::error::*;
+
+    let (rest, hstr) = preceded(tag("="), hex_digit1)(input)?;
+
+    let parsed = u8::from_str_radix(hstr, 16)
+        .map_err(|_| nom::Err::Error(Error::new(input, ErrorKind::Verify)))?;
+
+    Ok((rest, QuotedChunk::Encoded(parsed)))
+}
+
+//base64 (maybe use a crate)
+
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    // =?iso8859-1?Q?Accus=E9_de_r=E9ception_(affich=E9)?=
+
+    #[test]
+    fn test_ptext() {
+        assert_eq!(
+            ptext("Accus=E9_de_r=E9ception_(affich=E9)"),
+            vec![
+                QuotedChunk::Safe("Accus"),
+            ]
+        );
+    }
+}

src/fragments/mod.rs

@@ -17,4 +17,6 @@ mod mailbox;
 pub mod section;
 pub mod trace;
 
+// MIME related
 pub mod mime;
+pub mod encoding;