🩹 Workaround servers that don't send req'd SP

In particular, iCloud doesn't send a `SP` after `* BYE`.  Although this
is technically a violation of the RFCs, RFC9051 did make `text`
optional.  So, in the spirit of RFC9051 Appx E 23, we don't require a
final SP when the `resp-text` is empty.

* See also https://www.rfc-editor.org/errata/eid7343
* Fixes #229

Author: nevans

lib/net/imap/response_parser.rb

@@ -777,34 +777,47 @@ def response_data__ignored; response_data__unhandled(IgnoredResponse) end
 
       # RFC3501 & RFC9051:
       #   response-tagged = tag SP resp-cond-state CRLF
-      #
-      #   resp-cond-state = ("OK" / "NO" / "BAD") SP resp-text
-      #                       ; Status condition
-      #
-      #   tag             = 1*<any ASTRING-CHAR except "+">
       def response_tagged
-        tag  = tag();                 SP!
-        name = resp_cond_state__name; SP!
-        TaggedResponse.new(tag, name, resp_text, @str)
+        TaggedResponse.new(tag, *(SP!; resp_cond_state), @str)
       end
 
       # RFC3501 & RFC9051:
       #   resp-cond-state  = ("OK" / "NO" / "BAD") SP resp-text
+      #
+      # NOTE: In the spirit of RFC9051 Appx E 23 (and to workaround existing
+      # servers), we don't require a final SP and instead parse this as:
+      #
+      #   resp-cond-state = ("OK" / "NO" / "BAD") [SP resp-text]
+      def resp_cond_state
+        [resp_cond_state__name, SP? ? resp_text : ResponseText::EMPTY]
+      end
+
       def resp_cond_state__untagged
-        name = resp_cond_state__name; SP!
-        UntaggedResponse.new(name, resp_text, @str)
+        UntaggedResponse.new(*resp_cond_state, @str)
       end
 
       #   resp-cond-auth   = ("OK" / "PREAUTH") SP resp-text
+      #
+      # NOTE: In the spirit of RFC9051 Appx E 23 (and to workaround existing
+      # servers), we don't require a final SP and instead parse this as:
+      #
+      #   resp-cond-auth   = ("OK" / "PREAUTH") [SP resp-text]
       def resp_cond_auth
-        name = resp_cond_auth__name; SP!
-        UntaggedResponse.new(name, resp_text, @str)
+        UntaggedResponse.new(resp_cond_auth__name,
+                             SP? ? resp_text : ResponseText::EMPTY,
+                             @str)
       end
 
       #   resp-cond-bye    = "BYE" SP resp-text
+      #
+      # NOTE: In the spirit of RFC9051 Appx E 23 (and to workaround existing
+      # servers), we don't require a final SP and instead parse this as:
+      #
+      #   resp-cond-bye    = "BYE" [SP resp-text]
       def resp_cond_bye
-        name = label(BYE); SP!
-        UntaggedResponse.new(name, resp_text, @str)
+        UntaggedResponse.new(label(BYE),
+                             SP? ? resp_text : ResponseText::EMPTY,
+                             @str)
       end
 
       #   message-data    = nz-number SP ("EXPUNGE" / ("FETCH" SP msg-att))

test/net/imap/fixtures/response_parser/resp_cond_examples.yml

@@ -117,3 +117,36 @@
         code:
         text: "Autologout; idle for too long"
       raw_data: "* BYE Autologout; idle for too long\r\n"
+
+  response-tagged_without_SP_resp-text:
+    :response: "tag0001 OK\r\n"
+    :expected: !ruby/struct:Net::IMAP::TaggedResponse
+      tag: tag0001
+      name: OK
+      data: !ruby/struct:Net::IMAP::ResponseText
+        text: ''
+      raw_data: "tag0001 OK\r\n"
+
+  resp-cond-state_without_SP_resp-text:
+    :response: "* BAD\r\n"
+    :expected: !ruby/struct:Net::IMAP::UntaggedResponse
+      name: BAD
+      data: !ruby/struct:Net::IMAP::ResponseText
+        text: ''
+      raw_data: "* BAD\r\n"
+
+  resp-cond-auth_without_SP_resp-text:
+    :response: "* PREAUTH\r\n"
+    :expected: !ruby/struct:Net::IMAP::UntaggedResponse
+      name: PREAUTH
+      data: !ruby/struct:Net::IMAP::ResponseText
+        text: ''
+      raw_data: "* PREAUTH\r\n"
+
+  resp-cond-bye_without_SP_resp-text:
+    :response: "* BYE\r\n"
+    :expected: !ruby/struct:Net::IMAP::UntaggedResponse
+      name: BYE
+      data: !ruby/struct:Net::IMAP::ResponseText
+        text: ''
+      raw_data: "* BYE\r\n"