Import upstream v0.16.23, stripped

Upstream commit: 9d1c75ab68435e4417337f768291e5f947686203
Enterprise-only files removed or emptied: 63
Enterprise-only snippets removed: 118 in 50 files
Dangling module declarations removed: 5
Edits turning enterprise off: 25
Third-party code: 14 files, 0 not in THIRD-PARTY.md
Verification: clean

One snippet more than v0.16.22, in crates/common/src/auth/authentication.rs
(3, was 2).

crates/pop3/src/protocol/response.rs

@@ -14,7 +14,7 @@ pub enum Response<'x, T> {
     List(Vec<T>),
     Message {
         bytes: SliceRange<'x>,
-        lines: u32,
+        lines: Option<u32>,
     },
     Capability {
         mechanisms: Vec<Mechanism>,
@@ -52,40 +52,65 @@ impl<'x, T: Display> Response<'x, T> {
                 buf
             }
             Response::Message { bytes, lines } => {
-                let mut buf = Vec::with_capacity(bytes.len() + 10);
-                buf.extend_from_slice(b"+OK ");
-                buf.extend_from_slice(bytes.len().to_string().as_bytes());
-                buf.extend_from_slice(b" octets\r\n");
-
-                let mut line_count = 0;
-                let mut last_byte = 0;
+                let lines = *lines;
+                let mut message = Vec::with_capacity(bytes.len() + 16);
+                let mut octets = 0;
+                let mut last_byte = b'\n';
+                let mut in_headers = lines.is_some();
+                let mut is_blank_line = true;
+                let mut body_lines = 0;
 
                 // Transparency procedure
                 for &byte in bytes.into_iter() {
                     // POP3 requires that lines end with CRLF, do this check to ensure that
                     if byte == b'\n' && last_byte != b'\r' {
-                        buf.push(b'\r');
+                        message.push(b'\r');
+                        octets += 1;
                     }
 
                     if byte == b'.' && last_byte == b'\n' {
-                        buf.push(b'.');
+                        message.push(b'.');
                     }
-                    buf.push(byte);
+                    message.push(byte);
+                    octets += 1;
                     last_byte = byte;
 
-                    if *lines > 0 && byte == b'\n' {
-                        line_count += 1;
-                        if line_count == *lines {
-                            break;
+                    match byte {
+                        b'\n' => {
+                            if in_headers {
+                                in_headers = !is_blank_line;
+                            } else {
+                                body_lines += 1;
+                            }
+                            if !in_headers && lines.is_some_and(|lines| body_lines >= lines) {
+                                break;
+                            }
+                            is_blank_line = true;
+                        }
+                        b'\r' => {}
+                        _ => {
+                            is_blank_line = false;
                         }
                     }
                 }
 
                 if last_byte != b'\n' {
-                    buf.extend_from_slice(b"\r\n");
+                    message.extend_from_slice(b"\r\n");
+                    octets += 2;
                 }
 
-                buf.extend_from_slice(b".\r\n");
+                if in_headers {
+                    message.extend_from_slice(b"\r\n");
+                    octets += 2;
+                }
+
+                message.extend_from_slice(b".\r\n");
+
+                let mut buf = Vec::with_capacity(message.len() + 24);
+                buf.extend_from_slice(b"+OK ");
+                buf.extend_from_slice(octets.to_string().as_bytes());
+                buf.extend_from_slice(b" octets\r\n");
+                buf.extend_from_slice(&message);
                 buf
             }
             Response::Capability { mechanisms, stls } => {
@@ -206,9 +231,51 @@ mod tests {
             (
                 Response::Message {
                     bytes: SliceRange::Split(b"Subject: test\r\n\r\n.\r\n", b"test.\r\n.test\r\na"),
-                    lines: 0,
+                    lines: None,
                 },
-                "+OK 35 octets\r\nSubject: test\r\n\r\n..\r\ntest.\r\n..test\r\na\r\n.\r\n",
+                "+OK 37 octets\r\nSubject: test\r\n\r\n..\r\ntest.\r\n..test\r\na\r\n.\r\n",
+            ),
+            (
+                Response::Message {
+                    bytes: SliceRange::Split(b"Subject: test\r\n\r\n.\r\n", b"test.\r\n.test\r\na"),
+                    lines: Some(0),
+                },
+                "+OK 17 octets\r\nSubject: test\r\n\r\n.\r\n",
+            ),
+            (
+                Response::Message {
+                    bytes: SliceRange::Split(b"Subject: test\r\n\r\n.\r\n", b"test.\r\n.test\r\na"),
+                    lines: Some(2),
+                },
+                "+OK 27 octets\r\nSubject: test\r\n\r\n..\r\ntest.\r\n.\r\n",
+            ),
+            (
+                Response::Message {
+                    bytes: SliceRange::Split(b"Subject: test\r\n\r\n.\r\n", b"test.\r\n.test\r\na"),
+                    lines: Some(100),
+                },
+                "+OK 37 octets\r\nSubject: test\r\n\r\n..\r\ntest.\r\n..test\r\na\r\n.\r\n",
+            ),
+            (
+                Response::Message {
+                    bytes: SliceRange::Single(b"Subject: test\n\nbody\n"),
+                    lines: None,
+                },
+                "+OK 23 octets\r\nSubject: test\r\n\r\nbody\r\n.\r\n",
+            ),
+            (
+                Response::Message {
+                    bytes: SliceRange::Single(b"Subject: test\n\n.leading dot\n"),
+                    lines: Some(1),
+                },
+                "+OK 31 octets\r\nSubject: test\r\n\r\n..leading dot\r\n.\r\n",
+            ),
+            (
+                Response::Message {
+                    bytes: SliceRange::Single(b".dot\r\nSubject: test\r\n"),
+                    lines: Some(3),
+                },
+                "+OK 23 octets\r\n..dot\r\nSubject: test\r\n\r\n.\r\n",
             ),
         ] {
             assert_eq!(expected, String::from_utf8(cmd.serialize()).unwrap());