feat: add quirk for missing space in continue req command

Refs: #638

Author: soywod

imap-codec/Cargo.toml

@@ -28,6 +28,7 @@ quirk = [
     "quirk_rectify_numbers",
     "quirk_trailing_space",
     "quirk_spaces_between_addresses",
+    "quirk_continue_req_space_relaxed",
 ]
 # Make `\r` in `\r\n` optional.
 quirk_crlf_relaxed = []
@@ -41,6 +42,8 @@ quirk_rectify_numbers = []
 quirk_spaces_between_addresses = []
 # Accept a trailing space in `STATUS` data response.
 quirk_trailing_space = []
+# Accept continuation request commands without required space `+\r\n`
+quirk_continue_req_space_relaxed = []
 
 # <Forward to imap-types>
 arbitrary = ["imap-types/arbitrary"]

imap-codec/src/response.rs

@@ -271,7 +271,11 @@ pub(crate) fn continue_req(input: &[u8]) -> IMAPResult<&[u8], CommandContinuatio
     }
 
     let mut parser = tuple((
-        tag(b"+ "),
+        tag(b"+"),
+        #[cfg(feature = "quirk_continue_req_space_relaxed")]
+        opt(sp),
+        #[cfg(not(feature = "quirk_continue_req_space_relaxed"))]
+        sp,
         alt((
             #[cfg(not(feature = "quirk_crlf_relaxed"))]
             map(
@@ -294,7 +298,7 @@ pub(crate) fn continue_req(input: &[u8]) -> IMAPResult<&[u8], CommandContinuatio
         crlf,
     ));
 
-    let (remaining, (_, either, _)) = parser(input)?;
+    let (remaining, (_, _, either, _)) = parser(input)?;
 
     let continue_request = match either {
         Either::Base64(data) => CommandContinuationRequest::base64(data),