Add InvalidHeaderName error (#608)

* Add InvalidHeaderName error

src/address/types.rs

@@ -224,11 +224,14 @@ impl AsRef<OsStr> for Address {
 #[derive(Debug, PartialEq, Clone, Copy)]
 /// Errors in email addresses parsing
 pub enum AddressError {
+    /// Missing domain or user
     MissingParts,
+    /// Unbalanced angle bracket
     Unbalanced,
+    /// Invalid email user
     InvalidUser,
+    /// Invalid email domain
     InvalidDomain,
-    InvalidUtf8b,
 }
 
 impl Error for AddressError {}
@@ -240,7 +243,6 @@ impl Display for AddressError {
             AddressError::Unbalanced => f.write_str("Unbalanced angle bracket"),
             AddressError::InvalidUser => f.write_str("Invalid email user"),
             AddressError::InvalidDomain => f.write_str("Invalid email domain"),
-            AddressError::InvalidUtf8b => f.write_str("Invalid UTF8b data"),
         }
     }
 }

src/lib.rs

@@ -176,8 +176,7 @@ mod test {
     use std::convert::TryFrom;
 
     use super::*;
-    use crate::message::header::Headers;
-    use crate::message::{header, Mailbox, Mailboxes};
+    use crate::message::{header, header::Headers, Mailbox, Mailboxes};
 
     #[test]
     fn envelope_from_headers() {

src/message/body.rs

@@ -19,7 +19,9 @@ pub struct Body {
 /// makes for a more efficient `Content-Transfer-Encoding` to be chosen.
 #[derive(Debug, Clone)]
 pub enum MaybeString {
+    /// Binary data
     Binary(Vec<u8>),
+    /// UTF-8 string
     String(String),
 }
 
@@ -204,6 +206,7 @@ impl MaybeString {
 /// **NOTE:** if using the specified `encoding` would result into a malformed
 /// body, this will panic!
 pub trait IntoBody {
+    /// Encode as valid body
     fn into_body(self, encoding: Option<ContentTransferEncoding>) -> Body;
 }
 

src/message/header/content.rs

@@ -13,11 +13,15 @@ use crate::BoxError;
 /// use-caches this header shouldn't be set manually.
 #[derive(Debug, Clone, Copy, PartialEq)]
 pub enum ContentTransferEncoding {
+    /// ASCII
     SevenBit,
+    /// Quoted-Printable encoding
     QuotedPrintable,
+    /// base64 encoding
     Base64,
-    // 8BITMIME
+    /// Requires `8BITMIME`
     EightBit,
+    /// Binary data
     Binary,
 }
 

src/message/header/mailbox.rs

@@ -1,6 +1,8 @@
 use super::{Header, HeaderName};
-use crate::message::mailbox::{Mailbox, Mailboxes};
-use crate::BoxError;
+use crate::{
+    message::mailbox::{Mailbox, Mailboxes},
+    BoxError,
+};
 
 /// Header which can contains multiple mailboxes
 pub trait MailboxesHeader {

src/message/header/mod.rs

@@ -2,14 +2,20 @@
 
 use std::{
     borrow::Cow,
+    error::Error,
     fmt::{self, Display, Formatter},
     ops::Deref,
 };
 
-pub use self::content_disposition::ContentDisposition;
-pub use self::content_type::{ContentType, ContentTypeErr};
-pub use self::date::Date;
-pub use self::{content::*, mailbox::*, special::*, textual::*};
+pub use self::{
+    content::*,
+    content_disposition::ContentDisposition,
+    content_type::{ContentType, ContentTypeErr},
+    date::Date,
+    mailbox::*,
+    special::*,
+    textual::*,
+};
 use crate::BoxError;
 
 mod content;
@@ -131,22 +137,48 @@ impl Display for Headers {
     }
 }
 
+/// A possible error when converting a `HeaderName` from another type.
+// comes from `http` crate
+#[allow(missing_copy_implementations)]
+#[derive(Clone)]
+pub struct InvalidHeaderName {
+    _priv: (),
+}
+
+impl fmt::Debug for InvalidHeaderName {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("InvalidHeaderName")
+            // skip _priv noise
+            .finish()
+    }
+}
+
+impl fmt::Display for InvalidHeaderName {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.write_str("invalid header name")
+    }
+}
+
+impl Error for InvalidHeaderName {}
+
 #[derive(Debug, Clone)]
 pub struct HeaderName(Cow<'static, str>);
 
 impl HeaderName {
-    pub fn new_from_ascii(ascii: String) -> Option<Self> {
+    /// Creates a new header name
+    pub fn new_from_ascii(ascii: String) -> Result<Self, InvalidHeaderName> {
         if !ascii.is_empty()
             && ascii.len() <= 76
             && ascii.is_ascii()
             && !ascii.contains(|c| c == ':' || c == ' ')
         {
-            Some(Self(Cow::Owned(ascii)))
+            Ok(Self(Cow::Owned(ascii)))
         } else {
-            None
+            Err(InvalidHeaderName { _priv: () })
         }
     }
 
+    /// Creates a new header name, panics on invalid name
     pub const fn new_from_ascii_str(ascii: &'static str) -> Self {
         macro_rules! static_assert {
             ($condition:expr) => {
@@ -482,27 +514,27 @@ mod tests {
 
     #[test]
     fn valid_headername() {
-        assert!(HeaderName::new_from_ascii(String::from("From")).is_some());
+        assert!(HeaderName::new_from_ascii(String::from("From")).is_ok());
     }
 
     #[test]
     fn non_ascii_headername() {
-        assert!(HeaderName::new_from_ascii(String::from("🌎")).is_none());
+        assert!(HeaderName::new_from_ascii(String::from("🌎")).is_err());
     }
 
     #[test]
     fn spaces_in_headername() {
-        assert!(HeaderName::new_from_ascii(String::from("From ")).is_none());
+        assert!(HeaderName::new_from_ascii(String::from("From ")).is_err());
     }
 
     #[test]
     fn colons_in_headername() {
-        assert!(HeaderName::new_from_ascii(String::from("From:")).is_none());
+        assert!(HeaderName::new_from_ascii(String::from("From:")).is_err());
     }
 
     #[test]
     fn empty_headername() {
-        assert!(HeaderName::new_from_ascii(String::from("")).is_none());
+        assert!(HeaderName::new_from_ascii(String::from("")).is_err());
     }
 
     #[test]

src/message/header/special.rs

@@ -1,5 +1,7 @@
-use crate::message::header::{Header, HeaderName};
-use crate::BoxError;
+use crate::{
+    message::header::{Header, HeaderName},
+    BoxError,
+};
 
 /// Message format version, defined in [RFC2045](https://tools.ietf.org/html/rfc2045#section-4)
 #[derive(Debug, Copy, Clone, PartialEq)]

src/transport/smtp/async_transport.rs

@@ -1,5 +1,7 @@
-use std::fmt::{self, Debug};
-use std::marker::PhantomData;
+use std::{
+    fmt::{self, Debug},
+    marker::PhantomData,
+};
 
 use async_trait::async_trait;