imapclient: initial VANISHED support

Author: WhyNotHugo

fetch.go

@@ -21,6 +21,7 @@ type FetchOptions struct {
 	ModSeq            bool                          // requires CONDSTORE
 
 	ChangedSince uint64 // requires CONDSTORE
+	Vanished     bool   // requires QRESYNC, only for UID FETCH with ChangedSince
 }
 
 // FetchItemBodyStructure contains FETCH options for the body structure.

imapclient/client.go

@@ -973,6 +973,11 @@ func (c *Client) readResponseData(typ string) error {
 		return c.handleFetch(num)
 	case "EXPUNGE":
 		return c.handleExpunge(num)
+	case "VANISHED":
+		if !c.dec.ExpectSP() {
+			return c.dec.Err()
+		}
+		return c.handleVanished()
 	case "SEARCH":
 		return c.handleSearch()
 	case "ESEARCH":
@@ -1187,6 +1192,13 @@ type UnilateralDataHandler struct {
 
 	// requires ENABLE METADATA or ENABLE SERVER-METADATA
 	Metadata func(mailbox string, entries []string)
+
+	// Called when the server sends an untagged VANISHED response.
+	//
+	// Requires QRESYNC extension (RFC 4551/7162). The parameter earlier
+	// indicates whether this response covers earlier expunges (true for
+	// SELECT QRESYNC responses, false for UID FETCH VANISHED responses).
+	Vanished func(uids imap.UIDSet, earlier bool)
 }
 
 // command is an interface for IMAP commands.

imapclient/enable.go

@@ -14,7 +14,7 @@ func (c *Client) Enable(caps ...imap.Cap) *EnableCommand {
 	// extensions we support here
 	for _, name := range caps {
 		switch name {
-		case imap.CapIMAP4rev2, imap.CapUTF8Accept, imap.CapMetadata, imap.CapMetadataServer:
+		case imap.CapIMAP4rev2, imap.CapUTF8Accept, imap.CapMetadata, imap.CapMetadataServer, imap.CapQResync, imap.CapCondStore:
 			// ok
 		default:
 			done := make(chan error)

imapclient/fetch.go

@@ -34,7 +34,11 @@ func (c *Client) Fetch(numSet imap.NumSet, options *imap.FetchOptions) *FetchCom
 	enc.SP().NumSet(numSet).SP()
 	writeFetchItems(enc.Encoder, numKind, options)
 	if options.ChangedSince != 0 {
-		enc.SP().Special('(').Atom("CHANGEDSINCE").SP().ModSeq(options.ChangedSince).Special(')')
+		enc.SP().Special('(').Atom("CHANGEDSINCE").SP().ModSeq(options.ChangedSince)
+		if options.Vanished {
+			enc.SP().Atom("VANISHED")
+		}
+		enc.Special(')')
 	}
 	enc.end()
 	return cmd

imapclient/select.go

@@ -17,8 +17,25 @@ func (c *Client) Select(mailbox string, options *imap.SelectOptions) *SelectComm
 	cmd := &SelectCommand{mailbox: mailbox}
 	enc := c.beginCommand(cmdName, cmd)
 	enc.SP().Mailbox(mailbox)
-	if options != nil && options.CondStore {
-		enc.SP().Special('(').Atom("CONDSTORE").Special(')')
+	if options != nil {
+		if options.QResync != nil {
+			// QRESYNC implies CONDSTORE
+			enc.SP().Special('(').Atom("QRESYNC").SP()
+			enc.Special('(')
+			enc.Number(options.QResync.UIDValidity).SP().ModSeq(options.QResync.ModSeq)
+			if options.QResync.KnownUIDs != nil {
+				enc.SP().NumSet(*options.QResync.KnownUIDs)
+				if options.QResync.SeqMatchData != nil {
+					enc.SP().Special('(')
+					enc.NumSet(options.QResync.SeqMatchData.KnownSeqSet).SP()
+					enc.NumSet(options.QResync.SeqMatchData.KnownUIDSet)
+					enc.Special(')')
+				}
+			}
+			enc.Special(')').Special(')')
+		} else if options.CondStore {
+			enc.SP().Special('(').Atom("CONDSTORE").Special(')')
+		}
 	}
 	enc.end()
 	return cmd

imapclient/vanished.go

@@ -0,0 +1,34 @@
+package imapclient
+
+import (
+	"github.com/emersion/go-imap/v2"
+)
+
+func (c *Client) handleVanished() error {
+	var earlier bool
+	if c.dec.Special('(') {
+		var atom string
+		if !c.dec.ExpectAtom(&atom) || atom != "EARLIER" || !c.dec.ExpectSpecial(')') {
+			return c.dec.Err()
+		}
+		earlier = true
+		if !c.dec.ExpectSP() {
+			return c.dec.Err()
+		}
+	}
+
+	var uids imap.UIDSet
+	if !c.dec.ExpectUIDSet(&uids) {
+		return c.dec.Err()
+	}
+
+	// Check if this is part of a SELECT command response
+	cmd := findPendingCmdByType[*SelectCommand](c)
+	if cmd != nil {
+		cmd.data.VanishedUIDs = uids
+	} else if handler := c.options.unilateralDataHandler().Vanished; handler != nil {
+		handler(uids, earlier)
+	}
+
+	return nil
+}

select.go

@@ -4,6 +4,23 @@ package imap
 type SelectOptions struct {
 	ReadOnly  bool
 	CondStore bool // requires CONDSTORE
+
+	// QRESYNC parameters (requires QRESYNC extension, RFC 5162)
+	QResync *SelectQResyncOptions
+}
+
+// SelectQResyncOptions contains QRESYNC parameters for SELECT.
+type SelectQResyncOptions struct {
+	UIDValidity uint32
+	ModSeq      uint64
+	KnownUIDs   *UIDSet // optional
+	SeqMatchData *SelectSeqMatchData // optional
+}
+
+// SelectSeqMatchData contains sequence match data for QRESYNC.
+type SelectSeqMatchData struct {
+	KnownSeqSet SeqSet
+	KnownUIDSet UIDSet
 }
 
 // SelectData is the data returned by a SELECT command.
@@ -28,4 +45,8 @@ type SelectData struct {
 	List *ListData // requires IMAP4rev2
 
 	HighestModSeq uint64 // requires CONDSTORE
+
+	// UIDs of messages that were expunged.
+	// Requires QRESYNC extension (RFC 4551/7162).
+	VanishedUIDs UIDSet // requires QRESYNC
 }