Truncate message times to the second when using the FS message store

The FS message store truncates message times to the second.

This means that a message sent out as 2020-01-01T00:00:00.123Z could be
sent later as part of a CHATHISTORY batch as 2020-01-01T00:00:00.000Z,
which could cause issues in clients.

One such issue is a client sending a MARKREAD for
2020-01-01T00:00:00.000Z, with another client considering the
2020-01-01T00:00:00.123Z message it has as unread.

This fixes the issue by truncating all message times to the second when
using the FS message store.

downstream.go

@@ -2281,7 +2281,7 @@ func (dc *downstreamConn) handleMessageRegistered(ctx context.Context, msg *irc.
 				dc.logger.Printf("broadcasting bouncer-wide %v: %v", msg.Command, text)
 
 				broadcastTags := tags.Copy()
-				broadcastTags["time"] = xirc.FormatServerTime(time.Now())
+				broadcastTags["time"] = dc.user.FormatServerTime(time.Now())
 				broadcastMsg := &irc.Message{
 					Tags:    broadcastTags,
 					Prefix:  servicePrefix,
@@ -2307,7 +2307,7 @@ func (dc *downstreamConn) handleMessageRegistered(ctx context.Context, msg *irc.
 			if casemapASCII(name) == serviceNickCM {
 				if dc.caps.IsEnabled("echo-message") {
 					echoTags := tags.Copy()
-					echoTags["time"] = xirc.FormatServerTime(time.Now())
+					echoTags["time"] = dc.user.FormatServerTime(time.Now())
 					dc.SendMessage(&irc.Message{
 						Tags:    echoTags,
 						Prefix:  dc.prefix(),
@@ -2351,7 +2351,7 @@ func (dc *downstreamConn) handleMessageRegistered(ctx context.Context, msg *irc.
 				}
 
 				echoTags := tags.Copy()
-				echoTags["time"] = xirc.FormatServerTime(time.Now())
+				echoTags["time"] = dc.user.FormatServerTime(time.Now())
 				if uc.account != "" {
 					echoTags["account"] = uc.account
 				}

msgstore/fs.go

@@ -96,6 +96,11 @@ var (
 	_ RenameNetworkStore = (*fsMessageStore)(nil)
 )
 
+func IsFSStore(store Store) bool {
+	_, ok := store.(*fsMessageStore)
+	return ok
+}
+
 func NewFSStore(root string, user *database.User) *fsMessageStore {
 	return &fsMessageStore{
 		root:  filepath.Join(root, escapeFilename(user.Username)),

upstream.go

@@ -486,8 +486,12 @@ func (uc *upstreamConn) handleMessage(ctx context.Context, msg *irc.Message) err
 		msg.Prefix = uc.serverPrefix
 	}
 
-	if _, ok := msg.Tags["time"]; !ok && !isNumeric(msg.Command) {
-		msg.Tags["time"] = xirc.FormatServerTime(time.Now())
+	if !isNumeric(msg.Command) {
+		t, err := time.Parse(xirc.ServerTimeLayout, string(msg.Tags["time"]))
+		if err != nil {
+			t = time.Now()
+		}
+		msg.Tags["time"] = uc.user.FormatServerTime(t)
 	}
 
 	switch msg.Command {

user.go

@@ -13,6 +13,8 @@ import (
 	"strings"
 	"time"
 
+	"git.sr.ht/~emersion/soju/xirc"
+
 	"github.com/SherClockHolmes/webpush-go"
 	"gopkg.in/irc.v4"
 
@@ -1114,6 +1116,15 @@ func (u *user) hasPersistentMsgStore() bool {
 	return !msgstore.IsMemoryStore(u.msgStore)
 }
 
+func (u *user) FormatServerTime(t time.Time) string {
+	if u.msgStore != nil && msgstore.IsFSStore(u.msgStore) {
+		// The FS message store truncates message timestamps to the second,
+		// so truncate them here to get consistent timestamps.
+		t = t.Truncate(time.Second)
+	}
+	return xirc.FormatServerTime(t)
+}
+
 // localAddrForHost returns the local address to use when connecting to host.
 // A nil address is returned when the OS should automatically pick one.
 func (u *user) localTCPAddrForHost(ctx context.Context, host string) (*net.TCPAddr, error) {