parse message-id

src/headers.rs

@@ -175,6 +175,18 @@ fn header_field(input: &str) -> IResult<&str, HeaderField> {
             (input, HeaderField::Bcc(body.unwrap_or(vec![])))
         },
 
+        // 3.6.4.  Identification Fields
+        "Message-ID" => {
+            unimplemented!();
+        },
+        "In-Reply-To" => {
+            unimplemented!();
+        },
+        "References" => {
+            unimplemented!();
+        },
+
+        // Rest
         "Subject" => {
             let (input, body) = unstructured(input)?;
             (input, HeaderField::Subject(body))

src/identification.rs

@@ -0,0 +1,54 @@
+use std::borrow::Cow;
+use nom::{
+    IResult,
+    branch::alt,
+    bytes::complete::{take_while, tag},
+    combinator::opt,
+    sequence::{delimited, pair, tuple},
+};
+
+use crate::whitespace::cfws;
+use crate::words::dot_atom_text;
+use crate::mailbox::is_dtext;
+use crate::model::MessageId;
+
+/// Message identifier
+///
+/// ```abnf
+///    msg-id          =   [CFWS] "<" id-left "@" id-right ">" [CFWS]
+/// ```
+pub fn msg_id(input: &str) -> IResult<&str, MessageId> {
+    let (input, (left, _, right)) = delimited(
+        pair(opt(cfws), tag("<")),
+        tuple((id_left, tag("@"), id_right)),
+        pair(tag(">"), opt(cfws)),
+    )(input)?;
+    Ok((input, MessageId{ left, right }))
+}
+
+// Missing obsolete
+fn id_left(input: &str) -> IResult<&str, &str> {
+    dot_atom_text(input)   
+}
+
+// Missing obsolete
+fn id_right(input: &str) -> IResult<&str, &str> {
+    alt((dot_atom_text, no_fold_litteral))(input)
+}
+
+fn no_fold_litteral(input: &str) -> IResult<&str, &str> {
+    delimited(tag("["), take_while(is_dtext), tag("]"))(input)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_msg_id() {
+        assert_eq!(
+            msg_id("<5678.21-Nov-1997@example.com>"),
+            Ok(("", MessageId{left: "5678.21-Nov-1997", right: "example.com"})),
+        );
+    }
+}

src/lib.rs

@@ -10,3 +10,4 @@ mod misc_token;
 // Header specific
 mod mailbox;
 mod address;
+mod identification;

src/mailbox.rs

@@ -118,7 +118,7 @@ fn inner_domain_litteral(input: &str) -> IResult<&str, String> {
 ///                       %d94-126 /         ;  characters not including
 ///                       obs-dtext          ;  "[", "]", or "\"
 /// ```
-fn is_dtext(c: char) -> bool {
+pub fn is_dtext(c: char) -> bool {
     (c >= '\x21' && c <= '\x5A') || (c >= '\x5E' && c <= '\x7E') || !c.is_ascii()
 }
 

src/model.rs

@@ -57,6 +57,12 @@ impl From<GroupRef> for AddressRef {
     }
 }
 
+#[derive(Debug, PartialEq)]
+pub struct MessageId<'a> {
+    pub left: &'a str,
+    pub right: &'a str,
+}
+
 /// Permissive Header Section
 ///
 /// This is a structure intended for parsing/decoding,

src/words.rs

@@ -40,7 +40,7 @@ pub fn atom(input: &str) -> IResult<&str, &str> {
 /// dot-atom-text
 ///
 /// `1*atext *("." 1*atext)`
-fn dot_atom_text(input: &str) -> IResult<&str, &str> {
+pub fn dot_atom_text(input: &str) -> IResult<&str, &str> {
     recognize(pair(take_while1(is_atext), many0(pair(tag("."), take_while1(is_atext)))))(input)
 }