ovs/lib/flow.c

/*
 * Copyright (c) 2008, 2009, 2010 Nicira Networks.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at:
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
#include <config.h>
#include <sys/types.h>
#include "flow.h"
#include <inttypes.h>
#include <netinet/in.h>
#include <stdlib.h>
#include <string.h>
#include "byte-order.h"
#include "coverage.h"
#include "dynamic-string.h"
#include "hash.h"
#include "ofpbuf.h"
#include "openflow/openflow.h"
#include "openvswitch/datapath-protocol.h"
#include "packets.h"
#include "unaligned.h"
#include "vlog.h"

VLOG_DEFINE_THIS_MODULE(flow);

static struct arp_eth_header *
pull_arp(struct ofpbuf *packet)
{
    return ofpbuf_try_pull(packet, ARP_ETH_HEADER_LEN);
}

static struct ip_header *
pull_ip(struct ofpbuf *packet)
{
    if (packet->size >= IP_HEADER_LEN) {
        struct ip_header *ip = packet->data;
        int ip_len = IP_IHL(ip->ip_ihl_ver) * 4;
        if (ip_len >= IP_HEADER_LEN && packet->size >= ip_len) {
            return ofpbuf_pull(packet, ip_len);
        }
    }
    return NULL;
}

static struct tcp_header *
pull_tcp(struct ofpbuf *packet)
{
    if (packet->size >= TCP_HEADER_LEN) {
        struct tcp_header *tcp = packet->data;
        int tcp_len = TCP_OFFSET(tcp->tcp_ctl) * 4;
        if (tcp_len >= TCP_HEADER_LEN && packet->size >= tcp_len) {
            return ofpbuf_pull(packet, tcp_len);
        }
    }
    return NULL;
}

static struct udp_header *
pull_udp(struct ofpbuf *packet)
{
    return ofpbuf_try_pull(packet, UDP_HEADER_LEN);
}

static struct icmp_header *
pull_icmp(struct ofpbuf *packet)
{
    return ofpbuf_try_pull(packet, ICMP_HEADER_LEN);
}

static void
parse_vlan(struct ofpbuf *b, struct flow *flow)
{
    struct qtag_prefix {
        ovs_be16 eth_type;      /* ETH_TYPE_VLAN */
        ovs_be16 tci;
    };

    if (b->size >= sizeof(struct qtag_prefix) + sizeof(ovs_be16)) {
        struct qtag_prefix *qp = ofpbuf_pull(b, sizeof *qp);
        flow->dl_vlan = qp->tci & htons(VLAN_VID_MASK);
        flow->dl_vlan_pcp = vlan_tci_to_pcp(qp->tci);
    }
}

static ovs_be16
parse_ethertype(struct ofpbuf *b)
{
    struct llc_snap_header *llc;
    ovs_be16 proto;

    proto = *(ovs_be16 *) ofpbuf_pull(b, sizeof proto);
    if (ntohs(proto) >= ODP_DL_TYPE_ETH2_CUTOFF) {
        return proto;
    }

    if (b->size < sizeof *llc) {
        return htons(ODP_DL_TYPE_NOT_ETH_TYPE);
    }

    llc = b->data;
    if (llc->llc.llc_dsap != LLC_DSAP_SNAP
        || llc->llc.llc_ssap != LLC_SSAP_SNAP
        || llc->llc.llc_cntl != LLC_CNTL_SNAP
        || memcmp(llc->snap.snap_org, SNAP_ORG_ETHERNET,
                  sizeof llc->snap.snap_org)) {
        return htons(ODP_DL_TYPE_NOT_ETH_TYPE);
    }

    ofpbuf_pull(b, sizeof *llc);
    return llc->snap.snap_type;
}

/* Initializes 'flow' members from 'packet', 'tun_id', and 'in_port.
 * Initializes 'packet' header pointers as follows:
 *
 *    - packet->l2 to the start of the Ethernet header.
 *
 *    - packet->l3 to just past the Ethernet header, or just past the
 *      vlan_header if one is present, to the first byte of the payload of the
 *      Ethernet frame.
 *
 *    - packet->l4 to just past the IPv4 header, if one is present and has a
 *      correct length, and otherwise NULL.
 *
 *    - packet->l7 to just past the TCP or UDP or ICMP header, if one is
 *      present and has a correct length, and otherwise NULL.
 */
int
flow_extract(struct ofpbuf *packet, ovs_be32 tun_id, uint16_t in_port,
             struct flow *flow)
{
    struct ofpbuf b = *packet;
    struct eth_header *eth;
    int retval = 0;

    COVERAGE_INC(flow_extract);

    memset(flow, 0, sizeof *flow);
    flow->tun_id = tun_id;
    flow->in_port = in_port;
    flow->dl_vlan = htons(OFP_VLAN_NONE);

    packet->l2 = b.data;
    packet->l3 = NULL;
    packet->l4 = NULL;
    packet->l7 = NULL;

    if (b.size < sizeof *eth) {
        return 0;
    }

    /* Link layer. */
    eth = b.data;
    memcpy(flow->dl_src, eth->eth_src, ETH_ADDR_LEN);
    memcpy(flow->dl_dst, eth->eth_dst, ETH_ADDR_LEN);

    /* dl_type, dl_vlan, dl_vlan_pcp. */
    ofpbuf_pull(&b, ETH_ADDR_LEN * 2);
    if (eth->eth_type == htons(ETH_TYPE_VLAN)) {
        parse_vlan(&b, flow);
    }
    flow->dl_type = parse_ethertype(&b);

    /* Network layer. */
    packet->l3 = b.data;
    if (flow->dl_type == htons(ETH_TYPE_IP)) {
        const struct ip_header *nh = pull_ip(&b);
        if (nh) {
            flow->nw_src = get_unaligned_u32(&nh->ip_src);
            flow->nw_dst = get_unaligned_u32(&nh->ip_dst);
            flow->nw_tos = nh->ip_tos & IP_DSCP_MASK;
            flow->nw_proto = nh->ip_proto;
            packet->l4 = b.data;
            if (!IP_IS_FRAGMENT(nh->ip_frag_off)) {
                if (flow->nw_proto == IP_TYPE_TCP) {
                    const struct tcp_header *tcp = pull_tcp(&b);
                    if (tcp) {
                        flow->tp_src = tcp->tcp_src;
                        flow->tp_dst = tcp->tcp_dst;
                        packet->l7 = b.data;
                    }
                } else if (flow->nw_proto == IP_TYPE_UDP) {
                    const struct udp_header *udp = pull_udp(&b);
                    if (udp) {
                        flow->tp_src = udp->udp_src;
                        flow->tp_dst = udp->udp_dst;
                        packet->l7 = b.data;
                    }
                } else if (flow->nw_proto == IP_TYPE_ICMP) {
                    const struct icmp_header *icmp = pull_icmp(&b);
                    if (icmp) {
                        flow->icmp_type = htons(icmp->icmp_type);
                        flow->icmp_code = htons(icmp->icmp_code);
                        packet->l7 = b.data;
                    }
                }
            } else {
                retval = 1;
            }
        }
    } else if (flow->dl_type == htons(ETH_TYPE_ARP)) {
        const struct arp_eth_header *arp = pull_arp(&b);
        if (arp && arp->ar_hrd == htons(1)
            && arp->ar_pro == htons(ETH_TYPE_IP)
            && arp->ar_hln == ETH_ADDR_LEN
            && arp->ar_pln == 4) {
            /* We only match on the lower 8 bits of the opcode. */
            if (ntohs(arp->ar_op) <= 0xff) {
                flow->nw_proto = ntohs(arp->ar_op);
            }

            if ((flow->nw_proto == ARP_OP_REQUEST)
                || (flow->nw_proto == ARP_OP_REPLY)) {
                flow->nw_src = arp->ar_spa;
                flow->nw_dst = arp->ar_tpa;
            }
        }
    }
    return retval;
}

/* Extracts the flow stats for a packet.  The 'flow' and 'packet'
 * arguments must have been initialized through a call to flow_extract().
 */
void
flow_extract_stats(const struct flow *flow, struct ofpbuf *packet,
        struct odp_flow_stats *stats)
{
    memset(stats, '\0', sizeof(*stats));

    if ((flow->dl_type == htons(ETH_TYPE_IP)) && packet->l4) {
        if ((flow->nw_proto == IP_TYPE_TCP) && packet->l7) {
            struct tcp_header *tcp = packet->l4;
            stats->tcp_flags = TCP_FLAGS(tcp->tcp_ctl);
        }
    }

    stats->n_bytes = packet->size;
    stats->n_packets = 1;
}

/* Extract 'flow' with 'wildcards' into the OpenFlow match structure
 * 'match'.  'flow_format' should be one of NXFF_*. */
void
flow_to_match(const struct flow *flow, uint32_t wildcards,
              int flow_format, struct ofp_match *match)
{
    if (flow_format != NXFF_TUN_ID_FROM_COOKIE) {
        wildcards &= OFPFW_ALL;
    }
    match->wildcards = htonl(wildcards);

    match->in_port = htons(flow->in_port == ODPP_LOCAL ? OFPP_LOCAL
                           : flow->in_port);
    match->dl_vlan = flow->dl_vlan;
    match->dl_vlan_pcp = flow->dl_vlan_pcp;
    memcpy(match->dl_src, flow->dl_src, ETH_ADDR_LEN);
    memcpy(match->dl_dst, flow->dl_dst, ETH_ADDR_LEN);
    match->dl_type = flow->dl_type;
    match->nw_src = flow->nw_src;
    match->nw_dst = flow->nw_dst;
    match->nw_tos = flow->nw_tos;
    match->nw_proto = flow->nw_proto;
    match->tp_src = flow->tp_src;
    match->tp_dst = flow->tp_dst;
    memset(match->pad1, '\0', sizeof match->pad1);
    memset(match->pad2, '\0', sizeof match->pad2);
}

void
flow_from_match(const struct ofp_match *match, int flow_format,
                ovs_be64 cookie, struct flow *flow, uint32_t *flow_wildcards)
{
	uint32_t wildcards = ntohl(match->wildcards);

    flow->nw_src = match->nw_src;
    flow->nw_dst = match->nw_dst;
    if (flow_format == NXFF_TUN_ID_FROM_COOKIE && !(wildcards & NXFW_TUN_ID)) {
        flow->tun_id = htonl(ntohll(cookie) >> 32);
    } else {
        wildcards |= NXFW_TUN_ID;
        flow->tun_id = 0;
    }
    flow->in_port = (match->in_port == htons(OFPP_LOCAL) ? ODPP_LOCAL
                     : ntohs(match->in_port));
    flow->dl_vlan = match->dl_vlan;
    flow->dl_vlan_pcp = match->dl_vlan_pcp;
    flow->dl_type = match->dl_type;
    flow->tp_src = match->tp_src;
    flow->tp_dst = match->tp_dst;
    memcpy(flow->dl_src, match->dl_src, ETH_ADDR_LEN);
    memcpy(flow->dl_dst, match->dl_dst, ETH_ADDR_LEN);
    flow->nw_tos = match->nw_tos;
    flow->nw_proto = match->nw_proto;
    if (flow_wildcards) {
        *flow_wildcards = wildcards;
    }
}

char *
flow_to_string(const struct flow *flow)
{
    struct ds ds = DS_EMPTY_INITIALIZER;
    flow_format(&ds, flow);
    return ds_cstr(&ds);
}

void
flow_format(struct ds *ds, const struct flow *flow)
{
    ds_put_format(ds, "tunnel%08"PRIx32":in_port%04"PRIx16
                      ":vlan%"PRIu16":pcp%"PRIu8
                      " mac"ETH_ADDR_FMT"->"ETH_ADDR_FMT
                      " type%04"PRIx16
                      " proto%"PRIu8
                      " tos%"PRIu8
                      " ip"IP_FMT"->"IP_FMT
                      " port%"PRIu16"->%"PRIu16,
                  ntohl(flow->tun_id),
                  flow->in_port,
                  ntohs(flow->dl_vlan),
                  flow->dl_vlan_pcp,
                  ETH_ADDR_ARGS(flow->dl_src),
                  ETH_ADDR_ARGS(flow->dl_dst),
                  ntohs(flow->dl_type),
                  flow->nw_proto,
                  flow->nw_tos,
                  IP_ARGS(&flow->nw_src),
                  IP_ARGS(&flow->nw_dst),
                  ntohs(flow->tp_src),
                  ntohs(flow->tp_dst));
}

void
flow_print(FILE *stream, const struct flow *flow)
{
    char *s = flow_to_string(flow);
    fputs(s, stream);
    free(s);
}

/* flow_wildcards functions. */

/* Given the wildcard bit count in bits 'shift' through 'shift + 5' (inclusive)
 * of 'wildcards', returns a 32-bit bit mask with a 1 in each bit that must
 * match and a 0 in each bit that is wildcarded.
 *
 * The bits in 'wildcards' are in the format used in enum ofp_flow_wildcards: 0
 * is exact match, 1 ignores the LSB, 2 ignores the 2 least-significant bits,
 * ..., 32 and higher wildcard the entire field.  This is the *opposite* of the
 * usual convention where e.g. /24 indicates that 8 bits (not 24 bits) are
 * wildcarded. */
ovs_be32
flow_nw_bits_to_mask(uint32_t wildcards, int shift)
{
    wildcards = (wildcards >> shift) & 0x3f;
    return wildcards < 32 ? htonl(~((1u << wildcards) - 1)) : 0;
}

/* Return 'wildcards' in "normal form":
 *
 *   - Forces unknown bits to 0.
 *
 *   - Forces nw_src and nw_dst masks greater than 32 to exactly 32.
 */
static inline uint32_t
flow_wildcards_normalize(uint32_t wildcards)
{
    wildcards &= wildcards & OVSFW_ALL;
    if (wildcards & (0x20 << OFPFW_NW_SRC_SHIFT)) {
        wildcards &= ~(0x1f << OFPFW_NW_SRC_SHIFT);
    }
    if (wildcards & (0x20 << OFPFW_NW_DST_SHIFT)) {
        wildcards &= ~(0x1f << OFPFW_NW_DST_SHIFT);
    }
    return wildcards;
}

/* Initializes 'wc' from 'wildcards', which may be any combination of the
 * OFPFW_* and OVSFW_* wildcard bits. */
void
flow_wildcards_init(struct flow_wildcards *wc, uint32_t wildcards)
{
    wc->wildcards = flow_wildcards_normalize(wildcards);
    wc->nw_src_mask = flow_nw_bits_to_mask(wc->wildcards, OFPFW_NW_SRC_SHIFT);
    wc->nw_dst_mask = flow_nw_bits_to_mask(wc->wildcards, OFPFW_NW_DST_SHIFT);
}

/* Initializes 'wc' as an exact-match set of wildcards; that is, 'wc' does not
 * wildcard any bits or fields. */
void
flow_wildcards_init_exact(struct flow_wildcards *wc)
{
    flow_wildcards_init(wc, 0);
}

static inline uint32_t
combine_nw_bits(uint32_t wb1, uint32_t wb2, int shift)
{
    uint32_t sb1 = (wb1 >> shift) & 0x3f;
    uint32_t sb2 = (wb2 >> shift) & 0x3f;
    return MAX(sb1, sb2) << shift;
}

/* Initializes 'dst' as the combination of wildcards in 'src1' and 'src2'.
 * That is, a bit or a field is wildcarded in 'dst' if it is wildcarded in
 * 'src1' or 'src2' or both.  */
void
flow_wildcards_combine(struct flow_wildcards *dst,
                       const struct flow_wildcards *src1,
                       const struct flow_wildcards *src2)
{
    uint32_t wb1 = src1->wildcards;
    uint32_t wb2 = src2->wildcards;

    dst->wildcards = (wb1 | wb2) & ~(OFPFW_NW_SRC_MASK | OFPFW_NW_DST_MASK);
    dst->wildcards |= combine_nw_bits(wb1, wb2, OFPFW_NW_SRC_SHIFT);
    dst->wildcards |= combine_nw_bits(wb1, wb2, OFPFW_NW_DST_SHIFT);
    dst->nw_src_mask = src1->nw_src_mask & src2->nw_src_mask;
    dst->nw_dst_mask = src1->nw_dst_mask & src2->nw_dst_mask;
}

/* Returns a hash of the wildcards in 'wc'. */
uint32_t
flow_wildcards_hash(const struct flow_wildcards *wc)
{
    /* There is no need to include nw_src_mask or nw_dst_mask because they do
     * not add any information (they can be computed from wc->wildcards).  */
    return hash_int(wc->wildcards, 0);
}

/* Returns true if 'a' and 'b' represent the same wildcards, false if they are
 * different. */
bool
flow_wildcards_equal(const struct flow_wildcards *a,
                     const struct flow_wildcards *b)
{
    return a->wildcards == b->wildcards;
}

/* Returns true if at least one bit or field is wildcarded in 'a' but not in
 * 'b', false otherwise. */
bool
flow_wildcards_has_extra(const struct flow_wildcards *a,
                         const struct flow_wildcards *b)
{
#define OFPFW_NW_MASK (OFPFW_NW_SRC_MASK | OFPFW_NW_DST_MASK)
    return ((a->wildcards & ~(b->wildcards | OFPFW_NW_MASK))
            || (a->nw_src_mask & b->nw_src_mask) != b->nw_src_mask
            || (a->nw_dst_mask & b->nw_dst_mask) != b->nw_dst_mask);
}

static int
count_ones(ovs_be32 mask)
{
#if __GNUC__ >= 4
    return __builtin_popcount(mask);
#else
    int bits;

    for (bits = 0; mask; bits++) {
        mask &= mask - 1;
    }

    return bits;
#endif
}

static bool
set_nw_mask(struct flow_wildcards *wc, ovs_be32 mask,
            ovs_be32 *maskp, int shift)
{
    int wcbits = 32 - count_ones(mask);
    if (flow_nw_bits_to_mask(wcbits, 0) == mask) {
        wc->wildcards &= ~(0x3f << shift);
        wc->wildcards |= wcbits << shift;
        *maskp = mask;
        return true;
    } else {
        return false;
    }
}

/* Sets the IP (or ARP) source wildcard mask to CIDR 'mask' (consisting of N
 * high-order 1-bit and 32-N low-order 0-bits).  Returns true if successful,
 * false if 'mask' is not a CIDR mask.  */
bool
flow_wildcards_set_nw_src_mask(struct flow_wildcards *wc, ovs_be32 mask)
{
    return set_nw_mask(wc, mask, &wc->nw_src_mask, OFPFW_NW_SRC_SHIFT);
}

/* Sets the IP (or ARP) destination wildcard mask to CIDR 'mask' (consisting of
 * N high-order 1-bit and 32-N low-order 0-bits).  Returns true if successful,
 * false if 'mask' is not a CIDR mask.  */
bool
flow_wildcards_set_nw_dst_mask(struct flow_wildcards *wc, ovs_be32 mask)
{
    return set_nw_mask(wc, mask, &wc->nw_dst_mask, OFPFW_NW_DST_SHIFT);
}