tcp midstream: fix window scaling

If stream is picked by ACK, we can't know the wscale, so we assume it's
set to max. Howver, we didn't apply this to the initial window size we
set.

src/stream-tcp.c

@@ -982,11 +982,16 @@ static int StreamTcpPacketStateNone(ThreadVars *tv, Packet *p,
         ssn->flags = STREAMTCP_FLAG_MIDSTREAM;
         ssn->flags |= STREAMTCP_FLAG_MIDSTREAM_ESTABLISHED;
 
+        /** window scaling for midstream pickups, we can't do much other
+         *  than assume that it's set to the max value: 14 */
+        ssn->client.wscale = TCP_WSCALE_MAX;
+        ssn->server.wscale = TCP_WSCALE_MAX;
+
         /* set the sequence numbers and window */
         ssn->client.isn = TCP_GET_SEQ(p) - 1;
         STREAMTCP_SET_RA_BASE_SEQ(&ssn->client, ssn->client.isn);
         ssn->client.next_seq = TCP_GET_SEQ(p) + p->payload_len;
-        ssn->client.window = TCP_GET_WINDOW(p);
+        ssn->client.window = TCP_GET_WINDOW(p) << ssn->client.wscale;
         ssn->client.last_ack = TCP_GET_SEQ(p);
         ssn->client.next_win = ssn->client.last_ack + ssn->client.window;
         SCLogDebug("ssn %p: ssn->client.isn %u, ssn->client.next_seq %u",
@@ -1005,11 +1010,6 @@ static int StreamTcpPacketStateNone(ThreadVars *tv, Packet *p,
                 "ssn->server.last_ack %"PRIu32"", ssn,
                 ssn->client.last_ack, ssn->server.last_ack);
 
-        /** window scaling for midstream pickups, we can't do much other
-         *  than assume that it's set to the max value: 14 */
-        ssn->client.wscale = TCP_WSCALE_MAX;
-        ssn->server.wscale = TCP_WSCALE_MAX;
-
         /* Set the timestamp value for both streams, if packet has timestamp
          * option enabled.*/
         if (p->tcpvars.ts != NULL) {