Send a MODE request when JOINing

This kind of reverts/fixes f1cb09bd9c.

Robby found a bug with evil ChanServ which goes like this:

- You join an empty, but registered channel and the IRCd applies its default
  modes (+nt), but ZNC didn't ask for MODE, so doesn't know this.
- ChanServ applies whatever channel modes it wants to apply. This causes ZNC to
  see a mode change (e.g. +s).

The result of this is that ZNC thinks that the channel has mode +s and it will
tell every client that connects to it about this.

The fix is to send a MODE request when JOINing. To make sure that we don't
confuse clients, we block the reply.

Signed-off-by: Uli Schlachter <psychon@znc.in>

IRCSock.cpp

@@ -196,6 +196,15 @@ void CIRCSock::ReadLine(const CString& sData) {
 
 				if (pChan) {
 					pChan->SetModes(sRest.Token(1, true));
+
+					// We don't SetModeKnown(true) here,
+					// because a 329 will follow
+					if (!pChan->IsModeKnown()) {
+						// When we JOIN, we send a MODE
+						// request. This makes sure the
+						// reply isn't forwarded.
+						return;
+					}
 				}
 			}
 				break;
@@ -206,6 +215,14 @@ void CIRCSock::ReadLine(const CString& sData) {
 				if (pChan) {
 					unsigned long ulDate = sLine.Token(4).ToULong();
 					pChan->SetCreationDate(ulDate);
+
+					if (!pChan->IsModeKnown()) {
+						pChan->SetModeKnown(true);
+						// When we JOIN, we send a MODE
+						// request. This makes sure the
+						// reply isn't forwarded.
+						return;
+					}
 				}
 			}
 				break;
@@ -455,6 +472,7 @@ void CIRCSock::ReadLine(const CString& sData) {
 					pChan->ResetJoinTries();
 					pChan->Enable();
 					pChan->SetIsOn(true);
+					PutIRC("MODE " + sChan);
 				}
 			} else {
 				pChan = m_pUser->FindChan(sChan);