altq, v6 ack prioritisation

[Stuart Henderson]

allow IPv6 empty TCP acks to be prioritized as happens with v4
using similar code to v4. tested over pppoe(4). ok?

Index: pf.c
===================================================================
RCS file: /cvs/src/sys/net/pf.c,v
retrieving revision 1.734
diff -u -p -r1.734 pf.c
--- pf.c        5 Apr 2011 13:48:18 -0000       1.734
+++ pf.c        5 Apr 2011 15:05:17 -0000
@@ -6021,6 +6021,7 @@ pf_test6(int fwdir, struct ifnet *ifp, s
        union pf_headers         hdrs;
        int                      off, hdrlen;
        int                      dir = (fwdir == PF_FWD) ? PF_OUT : fwdir;
+       u_int32_t                qid, pqid = 0;
 
        if (!pf_status.running)
                return (PF_PASS);
@@ -6098,6 +6099,8 @@ pf_test6(int fwdir, struct ifnet *ifp, s
        switch (pd.proto) {
 
        case IPPROTO_TCP: {
+               if ((pd.hdr.tcp->th_flags & TH_ACK) && pd.p_len == 0)
+                       pqid = 1;
                action = pf_normalize_tcp(dir, kif, m, 0, off, h, &pd);
                if (action == PF_DROP)
                        goto done;
@@ -6188,10 +6191,19 @@ done:
        }
 
        if (action != PF_DROP) {
-               if (s)
+               if (s) {
                        pf_scrub_ip6(&m, s->min_ttl);
-               else
+                       if (pqid || (pd.tos & IPTOS_LOWDELAY))
+                               qid = s->pqid;
+                       else
+                               qid = s->qid;
+               } else {
                        pf_scrub_ip6(&m, r->min_ttl);
+                       if (pqid || (pd.tos & IPTOS_LOWDELAY))
+                               qid = r->pqid;
+                       else
+                               qid = r->qid;
+               }
        }
        if (s && s->tag)
                pf_tag_packet(m, s ? s->tag : 0, s->rtableid[pd.didx]);
@@ -6200,13 +6212,9 @@ done:
                m->m_pkthdr.pf.statekey = s->key[PF_SK_STACK];
 
 #ifdef ALTQ
-       if (action == PF_PASS && s && s->qid) {
-               if (pd.tos & IPTOS_LOWDELAY)
-                       m->m_pkthdr.pf.qid = s->pqid;
-               else
-                       m->m_pkthdr.pf.qid = s->qid;
-               /* add hints for ecn */
-               m->m_pkthdr.pf.hdr = h;
+       if (action == PF_PASS && qid) {
+               m->m_pkthdr.pf.qid = qid;
+               m->m_pkthdr.pf.hdr = h; /* add hints for ecn */
        }
 #endif /* ALTQ */