fix(email): Fix mimebody DKIM body-hash computation

src/message/mimebody.rs

@@ -17,6 +17,15 @@ pub(super) enum Part {
     Multi(MultiPart),
 }
 
+impl Part {
+    pub(super) fn body_raw(&self) -> Vec<u8> {
+        match self {
+            Part::Single(part) => part.body_raw(),
+            Part::Multi(part) => part.body_raw(),
+        }
+    }
+}
+
 impl EmailFormat for Part {
     fn format(&self, out: &mut Vec<u8>) {
         match self {
@@ -132,6 +141,13 @@ impl SinglePart {
         self.format(&mut out);
         out
     }
+
+    pub(super) fn body_raw(&self) -> Vec<u8> {
+        let mut out = Vec::new();
+        out.extend_from_slice(&self.body);
+        out.extend_from_slice(b"\r\n");
+        out
+    }
 }
 
 impl EmailFormat for SinglePart {
@@ -373,6 +389,24 @@ impl MultiPart {
         self.format(&mut out);
         out
     }
+
+    pub(super) fn body_raw(&self) -> Vec<u8> {
+        let mut out = Vec::new();
+
+        let boundary = self.boundary();
+
+        for part in &self.parts {
+            out.extend_from_slice(b"--");
+            out.extend_from_slice(boundary.as_bytes());
+            out.extend_from_slice(b"\r\n");
+            part.format(&mut out);
+        }
+
+        out.extend_from_slice(b"--");
+        out.extend_from_slice(boundary.as_bytes());
+        out.extend_from_slice(b"--\r\n");
+        out
+    }
 }
 
 impl EmailFormat for MultiPart {

src/message/mod.rs

@@ -525,7 +525,7 @@ impl Message {
     pub(crate) fn body_raw(&self) -> Vec<u8> {
         let mut out = Vec::new();
         match &self.body {
-            MessageBody::Mime(p) => p.format(&mut out),
+            MessageBody::Mime(p) => out = p.body_raw(),
             MessageBody::Raw(r) => out.extend_from_slice(r),
         };
         out.extend_from_slice(b"\r\n");