On Sun, Nov 09, 2003 at 05:19:07PM +0100, Andre Oppermann wrote:
> Hello all,
> 
> this patch contains three things (to be separated for committing):
> 
>  tcp_hostcache
> 
>   - removes protocol cloning from routing table (IPv4+6)
>   - removes rtentry pointer from inpcb and in6pcb
>   - removes ip route cache in ip_input.c (locking much easier)
>   - removes most (tcp specific) metrics from rtentry metrics
>   - adds a hostcache table which carries the metrics for tcp
>   - works transparently for IPv4 and IPv6
>   - is designed for concurrent access in SMP environments
>   - significant reduction of routing table size (no cloning anymore)
>   - eases many routing table locking situations in ip/tcp code
> 
>  ip_fastforward
> 
>   - removes ip_flow forwarding code
>   - adds full direct process-to-completion IPv4 forwarding code
>   - handles ip fragmentation incl. hw support (ip_flow did not)
>   - supports ipfw and ipfilter (ip_flow did not)
>   - supports divert and ipfw fwd (ip_flow did not)
>   - drops anything it can't handle back to normal ip_input
I have a few comments to this code, see inline, look for #jesper

Apart from that it looks good.

/Jesper

> +int
> +ip_fastforward(struct mbuf *m)
> +{
> +     struct ip *ip;
> +     struct mbuf *m0 = NULL;
> +#ifdef IPDIVERT
> +     struct ip *tip;
> +     struct mbuf *teem = NULL;
> +#endif
> +     struct mbuf *tag = NULL;
> +     struct route ro;
> +     struct sockaddr_in *dst = NULL;
> +     struct in_ifaddr *ia = NULL;
> +     struct ifaddr *ifa = NULL;
> +     struct ifnet *ifp = NULL;
> +     struct ip_fw_args args;
> +     in_addr_t odest, dest;
> +     u_short sum;
> +     int hlen;
> +     int error = 0;
> +     int ipfw;
> +
> +     /*
> +      * Are we active and forwarding packets?
> +      */
> +     if (!ipfastforward_active || !ipforwarding)
> +             return 0;
> +
> +     /*
> +      * If there is any MT_TAG we fall back to ip_input because we can't
> +      * handle TAGs here.
> +      */
> +     if (m && m->m_type == MT_TAG)
> +             return 0;
> +
> +     M_ASSERTVALID(m);
> +     M_ASSERTPKTHDR(m);
> +

[...]

> +
> +     /*
> +      * Only unicast IP, not from loopback, no L2 or IP broadcast,
> +      * no multicast, no INADDR_ANY
> +      */
> +     if ((m->m_pkthdr.rcvif->if_flags & IFF_LOOPBACK) ||
> +         (ntohl(ip->ip_src.s_addr) == (u_long)INADDR_BROADCAST) ||

#jesper
You will never see packets with a multicast source address.

> +         (ntohl(ip->ip_dst.s_addr) == (u_long)INADDR_BROADCAST) ||
> +         (IN_MULTICAST(ntohl(ip->ip_src.s_addr))) ||
> +         (IN_MULTICAST(ntohl(ip->ip_dst.s_addr))) ||
> +         (ip->ip_dst.s_addr == INADDR_ANY) )
> +             goto fallback;
> +
> +     /*
> +      * Is it for a local address on this host?
> +      */
> +     LIST_FOREACH(ia, INADDR_HASH(ip->ip_dst.s_addr), ia_hash) {
> +             if (IA_SIN(ia)->sin_addr.s_addr == ip->ip_dst.s_addr) {
> +                     goto fallback;
> +             }
> +     }
> +
> +     /*
> +      * Or is it for a local IP broadcast address on this host?
> +      */
> +     if (m->m_pkthdr.rcvif->if_flags & IFF_BROADCAST) {
> +             TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->if_addrhead, ifa_link) {
> +                     if (ifa->ifa_addr->sa_family != AF_INET)
> +                             continue;
> +                     ia = ifatoia(ifa);
> +                     if (ia->ia_netbroadcast.s_addr == ip->ip_dst.s_addr)
> +                             goto fallback;
> +                     if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr ==
> +                         ip->ip_dst.s_addr)
> +                             goto fallback;
> +                     continue;
> +fallback:
> +                     /* drop the packet back to netisr */
> +                     ip->ip_len = htons(ip->ip_len);
> +                     ip->ip_off = htons(ip->ip_off);
> +                     return 0;
> +             }
> +     }
> +     ipstat.ips_total++;

#jesper
If we stored special "for us" /32 routes in the routing table for
addresses configured on this host, we could avoid the above 2 loops,
which can quite expensive.

These special routes will simply mean that the packet is for us, and
needs to given to ip_input

> +     /**
> +      ** Third: incoming packet firewall processing
> +      **/
> +
> +     odest = dest = ip->ip_dst.s_addr;

#jesper
You could save a few cycles by doing

#ifdef PFIL_HOOKS
        odest = ip->ip_dst.s_addr;
        /*
         * Run through list of ipfilter hooks for input packets
         */
        if (pfil_run_hooks(&inet_pfil_hook, &m, m->m_pkthdr.rcvif, PFIL_IN) ||
            m == NULL)
                return 1;

        M_ASSERTVALID(m);
        M_ASSERTPKTHDR(m);

        ip = mtod(m, struct ip *);      /* if m changed during fw processing */
        dest = ip->ip_dst.s_addr;
#else
        odest = dest = ip->ip_dst.s_addr;
#endif

Thus avoiding writing to dest twice.

> +#ifdef PFIL_HOOKS
> +     /*
> +      * Run through list of ipfilter hooks for input packets
> +      */
> +     if (pfil_run_hooks(&inet_pfil_hook, &m, m->m_pkthdr.rcvif, PFIL_IN) ||
> +         m == NULL)
> +             return 1;
> +
> +     M_ASSERTVALID(m);
> +     M_ASSERTPKTHDR(m);
> +
> +     ip = mtod(m, struct ip *);      /* if m changed during fw processing */
> +     dest = ip->ip_dst.s_addr;
> +#endif
> +
> +     /*
> +      * Run through ipfw for input packets
> +      */
> +     if (fw_enable && IPFW_LOADED) {
> +             bzero(&args, sizeof(args));
> +             args.m = m;
> +             ipfw = 0;
> +
> +             ipfw = ip_fw_chk_ptr(&args);
> +             m = args.m;
> +
> +             M_ASSERTVALID(m);
> +             M_ASSERTPKTHDR(m);
> +
> +             /*
> +              * Packet denied, drop it
> +              */
> +             if ( (ipfw & IP_FW_PORT_DENY_FLAG) || m == NULL) {
> +                     if (m)
> +                             m_freem(m);
> +                     return 1;
> +             }
> +             /*
> +              * Send packet to the appropriate pipe
> +              */
> +                if (DUMMYNET_LOADED && (ipfw & IP_FW_PORT_DYNT_FLAG) != 0) {

#jesper 

Whitespace bug, spaces instead of tabs

> +                     ip_dn_io_ptr(m, ipfw & 0xffff, DN_TO_IP_IN, &args);
> +                     return 1;
> +             }
> +#ifdef IPDIVERT
> +             /*
> +              * Divert packet
> +              */
> +             if (ipfw != 0 && (ipfw & IP_FW_PORT_DYNT_FLAG) == 0) {
> +                     /*
> +                      * See if this is a fragment
> +                      */
> +                     if (ip->ip_off & (IP_MF | IP_OFFMASK)) {
> +                             MGETHDR(tag, M_DONTWAIT, MT_TAG);
> +                             if (tag == NULL) {
> +                                     m_freem(m);
> +                                     return 1;
> +                             }
> +                             tag->m_flags = PACKET_TAG_DIVERT;
> +                             tag->m_data = (caddr_t)(u_long)args.divert_rule;
> +                             tag->m_next = m;
> +                             m = tag;
> +                             tag = NULL;
> +
> +                                goto droptoours;

#jesper 

Whitespace bug, spaces instead of tabs

> +                     }
> +                     /*
> +                      * Tee packet
> +                      */
> +                     if ((ipfw & IP_FW_PORT_TEE_FLAG) != 0)
> +                             teem = m_dup(m, M_DONTWAIT);
> +                     else
> +                             teem = m;
> +                     if (teem == NULL)
> +                             goto passin;
> +
> +                     M_ASSERTVALID(teem);
> +                     M_ASSERTPKTHDR(teem);
> +
> +                     /*
> +                      * Delayed checksums are not compatible
> +                      */
> +                     if (teem->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
> +                             in_delayed_cksum(teem);
> +                             teem->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
> +                     }
> +                     /*
> +                      * Restore packet header fields to original values
> +                      */
> +                     tip = mtod(teem, struct ip *);
> +                     tip->ip_len = htons(tip->ip_len);
> +                     tip->ip_off = htons(tip->ip_off);
> +                     /*
> +                      * Deliver packet to divert input routine
> +                      */
> +                     divert_packet(teem, 0, ipfw & 0xffff, args.divert_rule);
> +                     /*
> +                      * If this was not tee, we are done
> +                      */
> +                     if ((ipfw & IP_FW_PORT_TEE_FLAG) == 0)
> +                             return 1;
> +                     /* Continue if it was tee */
> +                     goto passin;
> +             }
> +#endif
> +             if (ipfw == 0 && args.next_hop != NULL) {
> +                     dest = args.next_hop->sin_addr.s_addr;
> +                     goto passin;
> +             }
> +             /*
> +              * Let through or not?
> +              */
> +             if (ipfw != 0) {
> +                     m_freem(m);
> +                     return 1;
> +             }
> +     }
> +passin:
> +     ip = mtod(m, struct ip *);      /* if m changed during fw processing */
> +
> +     /*
> +      * Destination address changed?
> +      */
> +     if (odest != dest) {
> +             /*
> +              * Is it now for a local address on this host?
> +              */
> +             LIST_FOREACH(ia, INADDR_HASH(ip->ip_dst.s_addr), ia_hash) {
> +                     if (IA_SIN(ia)->sin_addr.s_addr == ip->ip_dst.s_addr)
> +                             goto forwardlocal;
> +             }

#jesper

Same comment as above - and do we really want to see if the original
destination address was ours if we're doing NAT ?

> +             /*
> +              * Go on with new destination address
> +              */
> +     }
> +
> +     M_ASSERTVALID(m);
> +     M_ASSERTPKTHDR(m);
> +
> +     /**
> +      ** Forth: decrement TTL and look up route
> +      **/
> +
> +     /*
> +      * Check TTL
> +      */
> +#ifdef IPSTEALTH
> +     if (!ipstealth) {
> +#endif
> +     if (ip->ip_ttl <= IPTTLDEC) {
> +             icmp_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS, NULL, NULL);
> +             return 1;
> +     }
> +
> +     /*
> +      * Decrement the TTL and incrementally change the checksum.
> +      * Don't bother doing this with hw checksum offloading.
> +      */
> +     ip->ip_ttl -= IPTTLDEC;
> +     if (ip->ip_sum >= (u_int16_t) ~htons(IPTTLDEC << 8))
> +             ip->ip_sum -= ~htons(IPTTLDEC << 8);
> +     else
> +             ip->ip_sum += htons(IPTTLDEC << 8);
> +#ifdef IPSTEALTH
> +     }
> +#endif
> +
> +     /*
> +      * Find route to destination.
> +      */
> +     bzero(&ro, sizeof(ro));
> +     dst = (struct sockaddr_in *)&ro.ro_dst;
> +     dst->sin_family = AF_INET;
> +     dst->sin_len = sizeof(*dst);
> +     dst->sin_addr.s_addr = dest;
> +     rtalloc(&ro);
> +
> +     /*
> +      * Route there and interface still up?
> +      */
> +     if ((ro.ro_rt) &&
> +         (ro.ro_rt->rt_flags & RTF_UP) &&
> +         (ro.ro_rt->rt_ifp->if_flags & IFF_UP)) {
> +             ia = ifatoia(ro.ro_rt->rt_ifa);
> +             ifp = ro.ro_rt->rt_ifp;
> +             if (ro.ro_rt->rt_flags & RTF_GATEWAY)
> +                     dst = (struct sockaddr_in *)ro.ro_rt->rt_gateway;
> +     } else {
> +             ipstat.ips_noroute++;
> +             ipstat.ips_cantforward++;
> +             icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, NULL, NULL);
> +             if (ro.ro_rt)
> +                     RTFREE(ro.ro_rt);
> +             return 1;
> +     }
> +
> +
> +     /**
> +      ** Fifth: outgoing firewall packet processing
> +      **/
> +
> +#ifdef PFIL_HOOKS
> +     /*
> +      * Run through list of hooks for output packets.
> +      */
> +     if (pfil_run_hooks(&inet_pfil_hook, &m, ifp, PFIL_OUT) ||
> +         m == NULL) {
> +             RTFREE(ro.ro_rt);
> +             return 1;
> +     }
> +
> +     M_ASSERTVALID(m);
> +     M_ASSERTPKTHDR(m);
> +
> +     ip = mtod(m, struct ip *);
> +     dest = ip->ip_dst.s_addr;
> +#endif
> +     if (fw_enable && IPFW_LOADED && !args.next_hop) {
> +                bzero(&args, sizeof(args));
> +             args.m = m;
> +             args.oif = ifp;
> +                ipfw = 0;
> +
> +             ipfw = ip_fw_chk_ptr(&args);
> +             m = args.m;
> +
> +             M_ASSERTVALID(m);
> +             M_ASSERTPKTHDR(m);
> +
> +             if ( (ipfw & IP_FW_PORT_DENY_FLAG) || m == NULL) {
> +                     if (m)
> +                             m_freem(m);
> +                     RTFREE(ro.ro_rt);
> +                     return 1;
> +             }
> +                if (DUMMYNET_LOADED && (ipfw & IP_FW_PORT_DYNT_FLAG) != 0) {

#jesper 

Whitespace bug, spaces instead of tabs

> +                     /*
> +                      * XXX note: if the ifp or rt entry are deleted
> +                      * while a pkt is in dummynet, we are in trouble!
> +                      */
> +                     args.ro = &ro;          /* dummynet does not save it */
> +                     args.dst = dst;
> +
> +                     ip_dn_io_ptr(m, ipfw & 0xffff, DN_TO_IP_OUT, &args);
> +                     RTFREE(ro.ro_rt);
> +                     return 1;
> +             }
> +#ifdef IPDIVERT
> +             if (ipfw != 0 && (ipfw & IP_FW_PORT_DYNT_FLAG) == 0) {
> +                     /*
> +                      * See if this is a fragment
> +                      */
> +                     if (ip->ip_off & (IP_MF | IP_OFFMASK)) {
> +                             MGETHDR(tag, M_DONTWAIT, MT_TAG);
> +                             if (tag == NULL) {
> +                                     m_freem(m);
> +                                     RTFREE(ro.ro_rt);
> +                                     return 1;
> +                             }
> +                             tag->m_flags = PACKET_TAG_DIVERT;
> +                             tag->m_data = (caddr_t)(u_int32_t)args.divert_rule;
> +                             tag->m_next = m;
> +                             m = tag;
> +                             tag = NULL;
> +
> +                             goto droptoours;
> +                     }
> +                     /*
> +                      * Tee packet
> +                      */
> +                     if ((ipfw & IP_FW_PORT_TEE_FLAG) != 0)
> +                             teem = m_dup(m, M_DONTWAIT);
> +                     else
> +                             teem = m;
> +                     if (teem == NULL)
> +                             goto passout;
> +
> +                     M_ASSERTVALID(m);
> +                     M_ASSERTPKTHDR(m);
> +
> +                     /*
> +                      * delayed checksums are not compatible with divert
> +                      */
> +                     if (teem->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
> +                             in_delayed_cksum(teem);
> +                             teem->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
> +                     }
> +                     /*
> +                      * Restore packet header fields to original values
> +                      */
> +                     tip = mtod(teem, struct ip *);
> +                     tip->ip_len = htons(tip->ip_len);
> +                     tip->ip_off = htons(tip->ip_off);
> +                     /*
> +                      * Deliver packet to divert input routine
> +                      */
> +                     divert_packet(teem, 0, ipfw & 0xffff, args.divert_rule);
> +                     /*
> +                      * If this was not tee, we are done
> +                      */
> +                     if ((ipfw & IP_FW_PORT_TEE_FLAG) == 0) {
> +                             RTFREE(ro.ro_rt);
> +                             return 1;
> +                     }
> +                     /* Continue if it was tee */
> +                     goto passout;
> +             }
> +#endif
> +             if (ipfw == 0 && args.next_hop != NULL) {
> +                     dest = args.next_hop->sin_addr.s_addr;
> +                     goto passout;
> +             }
> +             /*
> +              * Let through or not?
> +              */
> +             if (ipfw != 0) {
> +                     m_freem(m);
> +                     return 1;
> +             }
> +     }
> +passout:
> +     ip = mtod(m, struct ip *);
> +
> +     /*
> +      * Destination address changed?
> +      */
> +     if (odest != dest) {
> +             /*
> +              * Is it now for a local address on this host?
> +              */

#jesper

Again, do we really want to look for packets destined for us after being
translated ?

> +             LIST_FOREACH(ia, INADDR_HASH(ip->ip_dst.s_addr), ia_hash) {
> +                     if (IA_SIN(ia)->sin_addr.s_addr == ip->ip_dst.s_addr) {
> +forwardlocal:
> +                             if(args.next_hop) {
> +                                     MGETHDR(tag, M_DONTWAIT, MT_TAG);
> +                                     if (tag == NULL) {
> +                                             m_freem(m);
> +                                             if(ro.ro_rt)
> +                                                     RTFREE(ro.ro_rt);
> +                                             return 1;
> +                                     }
> +                                     tag->m_flags = PACKET_TAG_IPFORWARD;
> +                                     tag->m_data = (caddr_t)args.next_hop;
> +                                     tag->m_next = m;
> +                                     m = tag;
> +                                     tag = NULL;
> +                             }
> +#ifdef IPDIVERT
> +droptoours:  /* Used for DIVERT */
> +#endif
> +                             MGETHDR(tag, M_DONTWAIT, MT_TAG);
> +                             if (tag == NULL) {
> +                                     m_freem(m);
> +                                     if(ro.ro_rt)
> +                                             RTFREE(ro.ro_rt);
> +                                     return 1;
> +                             }
> +                                tag->m_flags = PACKET_TAG_IPFASTFWD_OURS;
> +                                tag->m_data = NULL;
> +                                tag->m_next = m;

#jesper 

Whitespace bug, spaces instead of tabs

> +                             m = tag;
> +                             tag = NULL;
> +
> +#if 0
> +                             /*
> +                              * Do some checks, we never know what fw has
> +                              * done to it.
> +                              */
> +                             if (m->m_pkthdr.rcvif == NULL)
> +                                     m->m_pkthdr.rcvif = ifunit("lo0");
> +                             if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
> +                                     m->m_pkthdr.csum_flags |=
> +                                         CSUM_DATA_VALID | CSUM_PSEUDO_HDR;
> +                                     m->m_pkthdr.csum_data = 0xffff;
> +                             }
> +                             m->m_pkthdr.csum_flags |=
> +                                 CSUM_IP_CHECKED | CSUM_IP_VALID;
> +#endif
> +
> +                             /* ip still points to the real packet */
> +                             ip->ip_len = htons(ip->ip_len);
> +                             ip->ip_off = htons(ip->ip_off);
> +
> +                             M_ASSERTVALID(m);
> +
> +                             /*
> +                              * Drop packet to ip_input
> +                              */
> +                             if (ro.ro_rt)
> +                                     RTFREE(ro.ro_rt);
> +                             return 0;
> +                     }
> +             }
> +             /*
> +              * Redo route lookup with new destination address
> +              */
> +             RTFREE(ro.ro_rt);
> +             bzero(&ro, sizeof(ro));
> +             dst = (struct sockaddr_in *)&ro.ro_dst;
> +             dst->sin_family = AF_INET;
> +             dst->sin_len = sizeof(*dst);
> +             dst->sin_addr.s_addr = dest;
> +             rtalloc(&ro);
> +
> +             /*
> +              * Route there and interface still up?
> +              */
> +             if ((ro.ro_rt) &&
> +                 (ro.ro_rt->rt_flags & RTF_UP) &&
> +                 (ro.ro_rt->rt_ifp->if_flags & IFF_UP)) {
> +                     ia = ifatoia(ro.ro_rt->rt_ifa);
> +                     ifp = ro.ro_rt->rt_ifp;
> +                     if (ro.ro_rt->rt_flags & RTF_GATEWAY)
> +                             dst = (struct sockaddr_in *)ro.ro_rt->rt_gateway;
> +             } else {
> +                     ipstat.ips_noroute++;
> +                     ipstat.ips_cantforward++;
> +                     icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, NULL, NULL);
> +                     if (ro.ro_rt)
> +                             RTFREE(ro.ro_rt);
> +                     return 1;
> +             }
> +     }
> +
> +     M_ASSERTVALID(m);
> +     M_ASSERTPKTHDR(m);
> +
> +     /**
> +      ** Sixth: send off the packet
> +      **/
> +
> +     /*
> +      * Check if packet fits MTU or if hardware will fragement for us
> +      */
> +     if (ip->ip_len <= ifp->if_mtu || (ifp->if_hwassist & CSUM_FRAGMENT &&
> +        ((ip->ip_off & IP_DF) == 0))) {
> +             /*
> +              * Restore packet header fields to original values
> +              */
> +             ip->ip_len = htons(ip->ip_len);
> +             ip->ip_off = htons(ip->ip_off);
> +             /*
> +              * Send off the packet via outgoing interface
> +              */
> +             error = (ifp->if_output)(ifp, m, (struct sockaddr *)dst, ro.ro_rt);
> +             if (ia) {
> +                     ia->ia_ifa.if_opackets++;
> +                     ia->ia_ifa.if_obytes += m->m_pkthdr.len;
> +             }
> +     } else {
> +             /*
> +              * Handle EMSGSIZE with icmp reply needfrag for TCP MTU discovery
> +              */
> +             if (ip->ip_off & IP_DF) {
> +                     icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_NEEDFRAG, NULL, ifp);
> +                     ipstat.ips_cantfrag++;
> +                     RTFREE(ro.ro_rt);
> +                     return 1;
> +             } else {
> +                     /*
> +                      * We have to fragement the packet
> +                      */
> +                     m->m_pkthdr.csum_flags |= CSUM_IP;
> +                     if (ip_fragment(ip, &m, ifp->if_mtu, ifp->if_hwassist,
> +                                     (~ifp->if_hwassist & CSUM_DELAY_IP))) {
> +                             m_freem(m);
> +                             RTFREE(ro.ro_rt);
> +                             return 1;
> +                     }
> +                     /*
> +                      * Send off the fragments via outgoing interface
> +                      */
> +                     for (; m; m = m0) {
> +                             m0 = m->m_nextpkt;
> +                             m->m_nextpkt = 0;
> +
> +                             M_ASSERTVALID(m);
> +                             M_ASSERTPKTHDR(m);
> +
> +                             if (error == 0) {
> +                                     error = (*ifp->if_output)(ifp, m,
> +                                             (struct sockaddr *)dst, ro.ro_rt);
> +                                     if (ia) {
> +                                             ia->ia_ifa.if_opackets++;
> +                                             ia->ia_ifa.if_obytes += 
> m->m_pkthdr.len;
> +                                     }
> +                             } else {
> +                                     m_freem(m);
> +                             }
> +                     }
> +                     if (error == 0)
> +                             ipstat.ips_fragmented++;
> +             }
> +     }
> +
> +     if (error == ENOBUFS)
> +             ipstat.ips_odropped++;
> +     else if (error != 0)
> +             ipstat.ips_odropped++;
> +     else {
> +             ro.ro_rt->rt_rmx.rmx_pksent++;
> +             ipstat.ips_forward++;
> +             ipstat.ips_fastforward++;
> +     }
> +     RTFREE(ro.ro_rt);
> +     return 1;
> +}
> +
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