implement the WITHIN IMAP extension, rfc 5032

for IMAP "SEARCH" command criteria "YOUNGER" and "OLDER".

Author: mjl-

README.md

@@ -138,9 +138,8 @@ https://nlnet.nl/project/Mox/.
 - "mox setup" command, with webapp for interactive setup
 - Automate DNS management, for setup and maintenance, such as DANE/DKIM key rotation.
 - Calendaring with CalDAV/iCal
-- More IMAP extensions (PREVIEW, WITHIN, IMPORTANT, COMPRESS=DEFLATE,
-  CREATE-SPECIAL-USE, SAVEDATE, UNAUTHENTICATE, REPLACE, QUOTA, NOTIFY,
-  MULTIAPPEND, OBJECTID, MULTISEARCH, THREAD, SORT)
+- More IMAP extensions (PREVIEW, IMPORTANT, COMPRESS=DEFLATE, UNAUTHENTICATE,
+  REPLACE, QUOTA, NOTIFY, MULTIAPPEND, OBJECTID, MULTISEARCH, THREAD, SORT)
 - Introbox, to which first-time senders are delivered
 - ARC, with forwarded email from trusted source
 - Add special IMAP mailbox ("Queue?") that contains queued but

imapserver/parse.go

@@ -793,6 +793,7 @@ var searchKeyWords = []string{
 	"BEFORE", "BODY",
 	"CC", "DELETED", "FLAGGED",
 	"FROM", "KEYWORD",
+	"OLDER", "YOUNGER", // WITHIN extension, ../rfc/5032:72
 	"NEW", "OLD", "ON", "RECENT", "SEEN",
 	"SINCE", "SUBJECT",
 	"TEXT", "TO",
@@ -933,6 +934,9 @@ func (p *parser) xsearchKey() *searchKey {
 		p.xspace()
 		sk.date = p.xdate() // ../rfc/8514:267
 	case "SAVEDATESUPPORTED":
+	case "OLDER", "YOUNGER":
+		p.xspace()
+		sk.number = int64(p.xnznumber())
 	default:
 		p.xerrorf("missing case for op %q", sk.op)
 	}

imapserver/search.go

@@ -5,6 +5,7 @@ import (
 	"log/slog"
 	"net/textproto"
 	"strings"
+	"time"
 
 	"github.com/mjl-/bstore"
 
@@ -539,6 +540,13 @@ func (s *search) match0(sk searchKey) bool {
 		// mailboxes, but we only have this metadata from the time we implemented this
 		// feature.
 		return s.m.SaveDate != nil
+	case "OLDER":
+		// ../rfc/5032:76
+		seconds := int64(time.Since(s.m.Received) / time.Second)
+		return seconds >= sk.number
+	case "YOUNGER":
+		seconds := int64(time.Since(s.m.Received) / time.Second)
+		return seconds <= sk.number
 	}
 
 	if s.p == nil {

imapserver/search_test.go

@@ -111,6 +111,12 @@ func TestSearch(t *testing.T) {
 	tc.transactf("ok", "search before 1-Jan-2020")
 	tc.xsearch() // Before is about received, not date header of message.
 
+	// WITHIN extension with OLDER & YOUNGER.
+	tc.transactf("ok", "search older 60")
+	tc.xsearch(1, 2, 3)
+	tc.transactf("ok", "search younger 60")
+	tc.xsearch()
+
 	// SAVEDATE extension.
 	tc.transactf("ok", "search savedbefore %s", saveDate.Add(24*time.Hour).Format("2-Jan-2006"))
 	tc.xsearch(1, 2, 3)

imapserver/server.go

@@ -160,12 +160,13 @@ var authFailDelay = time.Second  // After authentication failure.
 // QUOTA QUOTA=RES-STORAGE: ../rfc/9208:111
 // METADATA: ../rfc/5464
 // SAVEDATE: ../rfc/8514
+// WITHIN: ../rfc/5032
 //
 // We always announce support for SCRAM PLUS-variants, also on connections without
 // TLS. The client should not be selecting PLUS variants on non-TLS connections,
 // instead opting to do the bare SCRAM variant without indicating the server claims
 // to support the PLUS variant (skipping the server downgrade detection check).
-const serverCapabilities = "IMAP4rev2 IMAP4rev1 ENABLE LITERAL+ IDLE SASL-IR BINARY UNSELECT UIDPLUS ESEARCH SEARCHRES MOVE UTF8=ACCEPT LIST-EXTENDED SPECIAL-USE CREATE-SPECIAL-USE LIST-STATUS AUTH=SCRAM-SHA-256-PLUS AUTH=SCRAM-SHA-256 AUTH=SCRAM-SHA-1-PLUS AUTH=SCRAM-SHA-1 AUTH=CRAM-MD5 ID APPENDLIMIT=9223372036854775807 CONDSTORE QRESYNC STATUS=SIZE QUOTA QUOTA=RES-STORAGE METADATA SAVEDATE"
+const serverCapabilities = "IMAP4rev2 IMAP4rev1 ENABLE LITERAL+ IDLE SASL-IR BINARY UNSELECT UIDPLUS ESEARCH SEARCHRES MOVE UTF8=ACCEPT LIST-EXTENDED SPECIAL-USE CREATE-SPECIAL-USE LIST-STATUS AUTH=SCRAM-SHA-256-PLUS AUTH=SCRAM-SHA-256 AUTH=SCRAM-SHA-1-PLUS AUTH=SCRAM-SHA-1 AUTH=CRAM-MD5 ID APPENDLIMIT=9223372036854775807 CONDSTORE QRESYNC STATUS=SIZE QUOTA QUOTA=RES-STORAGE METADATA SAVEDATE WITHIN"
 
 type conn struct {
 	cid               int64

rfc/index.txt

@@ -190,7 +190,7 @@ https://www.iana.org/assignments/message-headers/message-headers.xhtml
 4731	Yes	-	IMAP4 Extension to SEARCH Command for Controlling What Kind of Information Is Returned
 4959	Yes	-	IMAP Extension for Simple Authentication and Security Layer (SASL) Initial Client Response
 4978	Roadmap	-	The IMAP COMPRESS Extension
-5032	Roadmap	-	WITHIN Search Extension to the IMAP Protocol
+5032	Yes	-	WITHIN Search Extension to the IMAP Protocol
 5092	Roadmap	-	IMAP URL Scheme
 5161	Yes	-	The IMAP ENABLE Extension
 5162	Yes	Obs	(RFC 7162) IMAP4 Extensions for Quick Mailbox Resynchronization