[NETFILTER]: PPTP conntrack: fix PPTP_IN_CALL message types

Fix incorrectly used message types and call IDs:

- PPTP_IN_CALL_REQUEST (PAC->PNS) contains a PptpInCallRequest (icreq)
  message and the PAC call ID

- PPTP_IN_CALL_REPLY (PNS->PAC) contains a PptpInCallReply (icack)
  message and the PNS call ID
Signed-off-by: NPatrick McHardy <kaber@trash.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv4/netfilter/ip_conntrack_helper_pptp.c

@@ -355,10 +355,10 @@ pptp_inbound_pkt(struct sk_buff **pskb,
 		if (info->sstate != PPTP_SESSION_CONFIRMED)
 			goto invalid;
 
-		pcid = pptpReq->icack.peersCallID;
-		DEBUGP("%s, PCID=%X\n", pptp_msg_name[msg], ntohs(pcid));
+		cid = pptpReq->icreq.callID;
+		DEBUGP("%s, CID=%X\n", pptp_msg_name[msg], ntohs(cid));
 		info->cstate = PPTP_CALL_IN_REQ;
-		info->pac_call_id = pcid;
+		info->pac_call_id = cid;
 		break;
 
 	case PPTP_IN_CALL_CONNECT:
@@ -458,15 +458,17 @@ pptp_outbound_pkt(struct sk_buff **pskb,
 		    info->cstate != PPTP_CALL_IN_REP)
 			goto invalid;
 
+		cid = pptpReq->icack.callID;
 		pcid = pptpReq->icack.peersCallID;
 		if (info->pac_call_id != pcid)
 			goto invalid;
-		DEBUGP("%s, CID=%X\n", pptp_msg_name[msg], ntohs(pcid));
+		DEBUGP("%s, CID=%X PCID=%X\n", pptp_msg_name[msg],
+		       ntohs(cid), ntohs(pcid));
 
 		if (pptpReq->icack.resultCode == PPTP_INCALL_ACCEPT) {
 			/* part two of the three-way handshake */
 			info->cstate = PPTP_CALL_IN_REP;
-			info->pns_call_id = pcid;
+			info->pns_call_id = cid;
 		} else
 			info->cstate = PPTP_CALL_NONE;
 		break;

net/ipv4/netfilter/ip_nat_helper_pptp.c

@@ -172,7 +172,7 @@ pptp_outbound_pkt(struct sk_buff **pskb,
 		ct_pptp_info->pns_call_id = new_callid;
 		break;
 	case PPTP_IN_CALL_REPLY:
-		cid_off = offsetof(union pptp_ctrl_union, icreq.callID);
+		cid_off = offsetof(union pptp_ctrl_union, icack.callID);
 		break;
 	case PPTP_CALL_CLEAR_REQUEST:
 		cid_off = offsetof(union pptp_ctrl_union, clrreq.callID);