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mitigate a potential DoS against websocket listeners

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Websocket listeners would process an arbitrary number of invalid
(non-text or blank) messages without throttling. This imposes fakelag
on such messages by treating them as blank lines.
This commit is contained in:
Shivaram Lingamneni 2020-08-05 15:00:39 -04:00
parent 8f490ae298
commit aad39024b9
1 changed files with 11 additions and 9 deletions
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20
irc/ircconn.go
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@ -124,16 +124,18 @@ func (wc IRCWSConn) WriteLines(buffers [][]byte) (err error) {
}
func (wc IRCWSConn) ReadLine() (line []byte, err error) {
for {
var messageType int
messageType, line, err = wc.conn.ReadMessage()
// on empty message or non-text message, try again, block if necessary
if err != nil || (messageType == websocket.TextMessage && len(line) != 0) {
if err == websocket.ErrReadLimit {
err = errReadQ
}
return
messageType, line, err := wc.conn.ReadMessage()
if err == nil {
if messageType == websocket.TextMessage {
return line, nil
} else {
// for purposes of fakelag, treat non-text message as an empty line
return nil, nil
}
} else if err == websocket.ErrReadLimit {
return line, errReadQ
} else {
return line, err
}
}