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connector: resend group messages as plain text when LINE says a member has Letter Sealing off #311

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connector: resend group messages as plain text when LINE says a member has Letter Sealing off #311

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9fb9532
connector: resend group messages as plain text when LINE says a membe…
indent Nov 10, 2026
0923a43
Use the zipped file for the plain-text resend after a ZIP retry
indent Nov 10, 2026
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43 changes: 32 additions & 11 deletions pkg/connector/send_message.go
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Original file line number Diff line number Diff line change
Expand Up @@ -661,6 +661,20 @@ func (lc *LineClient) HandleMatrixMessage(ctx context.Context, msg *bridgev2.Mat
contentMetadata[k] = v
}

fallBackToPlainText := func() {
plainText = true
delete(contentMetadata, "e2eeVersion")
if contentType == int(ContentText) {
plainTextBody = textBody
} else {
delete(contentMetadata, "OID")
delete(contentMetadata, "SID")
delete(contentMetadata, "ENC_KM")
plainMediaData = originalMediaData
plainThumbData = originalThumbData
}
}

// Encryption phase — skip entirely for plain text
if !plainText {
if isGroup {
Expand Down Expand Up @@ -693,19 +707,9 @@ func (lc *LineClient) HandleMatrixMessage(ctx context.Context, msg *bridgev2.Mat
lc.markGroupNoE2EE(portalMid)
lc.UserLogin.Bridge.Log.Warn().Err(err).Str("chat_mid", portalMid).
Msg("Failed to set up E2EE for group, falling back to plain text")
plainText = true
fallBackToPlainText()
chunks = nil
err = nil
delete(contentMetadata, "e2eeVersion")
if contentType == int(ContentText) {
plainTextBody = textBody
} else {
delete(contentMetadata, "OID")
delete(contentMetadata, "SID")
delete(contentMetadata, "ENC_KM")
plainMediaData = originalMediaData
plainThumbData = originalThumbData
}
}
}
} else {
Expand All @@ -731,6 +735,7 @@ func (lc *LineClient) HandleMatrixMessage(ctx context.Context, msg *bridgev2.Mat
lc.UserLogin.Bridge.Log.Info().Str("portal", portalMid).Int("content_type", contentType).Msg("Sending plain text message (no E2EE)")
}

sticonReplace := contentMetadata["REPLACE"]
if !plainText {
delete(contentMetadata, "REPLACE")
}
Expand Down Expand Up @@ -793,6 +798,7 @@ func (lc *LineClient) HandleMatrixMessage(ctx context.Context, msg *bridgev2.Mat
contentMetadata["FILE_NAME"] = zipFileName
contentMetadata["FILE_SIZE"] = fmt.Sprintf("%d", len(zipData))
lineMsg.ContentMetadata = contentMetadata
originalMediaData = zipData

if plainText {
plainMediaData = zipData
Expand Down Expand Up @@ -881,6 +887,21 @@ func (lc *LineClient) HandleMatrixMessage(ctx context.Context, msg *bridgev2.Mat
}
}

if err != nil && isGroup && !plainText && line.IsMemberSettingsOff(err) {
lc.markGroupNoE2EE(portalMid)
lc.UserLogin.Bridge.Log.Warn().Err(err).Str("chat_mid", portalMid).
Msg("LINE rejected encrypted group message because a member has Letter Sealing off, resending as plain text")
fallBackToPlainText()
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lineMsg.Chunks = nil
lineMsg.Text = plainTextBody
if sticonReplace != "" {
contentMetadata["REPLACE"] = sticonReplace
}
retryReqSeq := int(time.Now().UnixMilli() % 1_000_000_000)
lc.trackReqSeq(retryReqSeq)
sentMsg, err = sendLineMessage(retryReqSeq, lineMsg)
}

if shouldRetrySendWithoutReplyRelation(lineMsg, err) {
relatedMessageID := lineMsg.RelatedMessageID
clearReplyRelation(lineMsg)
Expand Down
5 changes: 5 additions & 0 deletions pkg/line/errors.go
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Original file line number Diff line number Diff line change
Expand Up @@ -364,6 +364,11 @@ func IsE2EEGroupMemberMismatch(err error) bool {
return ok && talk.Code == 99 && strings.EqualFold(strings.TrimSpace(talk.Reason), "member count mismatch")
}

func IsMemberSettingsOff(err error) bool {
talk, ok := parseTalkException(err)
return ok && talk.Code == 98 && strings.Contains(strings.ToLower(talk.Reason), "member settings off")
}

// IsTalkExceptionRateLimited returns true when LINE rejected a Talk API call
// for excessive access.
func IsTalkExceptionRateLimited(err error) bool {
Expand Down
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