lib/flow.c

   1 /*
   2  * Copyright (c) 2008, 2009, 2010 Nicira Networks.
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at:
   7  *
   8  *     http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16 #include <config.h>
  17 #include <sys/types.h>
  18 #include "flow.h"
  19 #include <inttypes.h>
  20 #include <netinet/in.h>
  21 #include <stdlib.h>
  22 #include <string.h>
  23 #include "coverage.h"
  24 #include "dynamic-string.h"
  25 #include "hash.h"
  26 #include "ofpbuf.h"
  27 #include "openflow/openflow.h"
  28 #include "openvswitch/datapath-protocol.h"
  29 #include "packets.h"
  30
  31 #include "vlog.h"
  32 #define THIS_MODULE VLM_flow
  33
  34 static struct arp_eth_header *
  35 pull_arp(struct ofpbuf *packet)
  36 {
  37     return ofpbuf_try_pull(packet, ARP_ETH_HEADER_LEN);
  38 }
  39
  40 static struct ip_header *
  41 pull_ip(struct ofpbuf *packet)
  42 {
  43     if (packet->size >= IP_HEADER_LEN) {
  44         struct ip_header *ip = packet->data;
  45         int ip_len = IP_IHL(ip->ip_ihl_ver) * 4;
  46         if (ip_len >= IP_HEADER_LEN && packet->size >= ip_len) {
  47             return ofpbuf_pull(packet, ip_len);
  48         }
  49     }
  50     return NULL;
  51 }
  52
  53 static struct tcp_header *
  54 pull_tcp(struct ofpbuf *packet)
  55 {
  56     if (packet->size >= TCP_HEADER_LEN) {
  57         struct tcp_header *tcp = packet->data;
  58         int tcp_len = TCP_OFFSET(tcp->tcp_ctl) * 4;
  59         if (tcp_len >= TCP_HEADER_LEN && packet->size >= tcp_len) {
  60             return ofpbuf_pull(packet, tcp_len);
  61         }
  62     }
  63     return NULL;
  64 }
  65
  66 static struct udp_header *
  67 pull_udp(struct ofpbuf *packet)
  68 {
  69     return ofpbuf_try_pull(packet, UDP_HEADER_LEN);
  70 }
  71
  72 static struct icmp_header *
  73 pull_icmp(struct ofpbuf *packet)
  74 {
  75     return ofpbuf_try_pull(packet, ICMP_HEADER_LEN);
  76 }
  77
  78 static struct eth_header *
  79 pull_eth(struct ofpbuf *packet)
  80 {
  81     return ofpbuf_try_pull(packet, ETH_HEADER_LEN);
  82 }
  83
  84 static struct vlan_header *
  85 pull_vlan(struct ofpbuf *packet)
  86 {
  87     return ofpbuf_try_pull(packet, VLAN_HEADER_LEN);
  88 }
  89
  90 /* Returns 1 if 'packet' is an IP fragment, 0 otherwise. */
  91 int
  92 flow_extract(struct ofpbuf *packet, uint16_t in_port, flow_t *flow)
  93 {
  94     struct ofpbuf b = *packet;
  95     struct eth_header *eth;
  96     int retval = 0;
  97
  98     COVERAGE_INC(flow_extract);
  99
 100     memset(flow, 0, sizeof *flow);
 101     flow->dl_vlan = htons(OFP_VLAN_NONE);
 102     flow->in_port = in_port;
 103
 104     packet->l2 = b.data;
 105     packet->l3 = NULL;
 106     packet->l4 = NULL;
 107     packet->l7 = NULL;
 108
 109     eth = pull_eth(&b);
 110     if (eth) {
 111         if (ntohs(eth->eth_type) >= OFP_DL_TYPE_ETH2_CUTOFF) {
 112             /* This is an Ethernet II frame */
 113             flow->dl_type = eth->eth_type;
 114         } else {
 115             /* This is an 802.2 frame */
 116             struct llc_header *llc = ofpbuf_at(&b, 0, sizeof *llc);
 117             struct snap_header *snap = ofpbuf_at(&b, sizeof *llc,
 118                                                  sizeof *snap);
 119             if (llc == NULL) {
 120                 return 0;
 121             }
 122             if (snap
 123                 && llc->llc_dsap == LLC_DSAP_SNAP
 124                 && llc->llc_ssap == LLC_SSAP_SNAP
 125                 && llc->llc_cntl == LLC_CNTL_SNAP
 126                 && !memcmp(snap->snap_org, SNAP_ORG_ETHERNET,
 127                            sizeof snap->snap_org)) {
 128                 flow->dl_type = snap->snap_type;
 129                 ofpbuf_pull(&b, LLC_SNAP_HEADER_LEN);
 130             } else {
 131                 flow->dl_type = htons(OFP_DL_TYPE_NOT_ETH_TYPE);
 132                 ofpbuf_pull(&b, sizeof(struct llc_header));
 133             }
 134         }
 135
 136         /* Check for a VLAN tag */
 137         if (flow->dl_type == htons(ETH_TYPE_VLAN)) {
 138             struct vlan_header *vh = pull_vlan(&b);
 139             if (vh) {
 140                 flow->dl_type = vh->vlan_next_type;
 141                 flow->dl_vlan = vh->vlan_tci & htons(VLAN_VID_MASK);
 142             }
 143         }
 144         memcpy(flow->dl_src, eth->eth_src, ETH_ADDR_LEN);
 145         memcpy(flow->dl_dst, eth->eth_dst, ETH_ADDR_LEN);
 146
 147         packet->l3 = b.data;
 148         if (flow->dl_type == htons(ETH_TYPE_IP)) {
 149             const struct ip_header *nh = pull_ip(&b);
 150             if (nh) {
 151                 flow->nw_src = nh->ip_src;
 152                 flow->nw_dst = nh->ip_dst;
 153                 flow->nw_proto = nh->ip_proto;
 154                 packet->l4 = b.data;
 155                 if (!IP_IS_FRAGMENT(nh->ip_frag_off)) {
 156                     if (flow->nw_proto == IP_TYPE_TCP) {
 157                         const struct tcp_header *tcp = pull_tcp(&b);
 158                         if (tcp) {
 159                             flow->tp_src = tcp->tcp_src;
 160                             flow->tp_dst = tcp->tcp_dst;
 161                             packet->l7 = b.data;
 162                         } else {
 163                             /* Avoid tricking other code into thinking that
 164                              * this packet has an L4 header. */
 165                             flow->nw_proto = 0;
 166                         }
 167                     } else if (flow->nw_proto == IP_TYPE_UDP) {
 168                         const struct udp_header *udp = pull_udp(&b);
 169                         if (udp) {
 170                             flow->tp_src = udp->udp_src;
 171                             flow->tp_dst = udp->udp_dst;
 172                             packet->l7 = b.data;
 173                         } else {
 174                             /* Avoid tricking other code into thinking that
 175                              * this packet has an L4 header. */
 176                             flow->nw_proto = 0;
 177                         }
 178                     } else if (flow->nw_proto == IP_TYPE_ICMP) {
 179                         const struct icmp_header *icmp = pull_icmp(&b);
 180                         if (icmp) {
 181                             flow->icmp_type = htons(icmp->icmp_type);
 182                             flow->icmp_code = htons(icmp->icmp_code);
 183                             packet->l7 = b.data;
 184                         } else {
 185                             /* Avoid tricking other code into thinking that
 186                              * this packet has an L4 header. */
 187                             flow->nw_proto = 0;
 188                         }
 189                     }
 190                 } else {
 191                     retval = 1;
 192                 }
 193             }
 194         } else if (flow->dl_type == htons(ETH_TYPE_ARP)) {
 195             const struct arp_eth_header *arp = pull_arp(&b);
 196             if (arp && arp->ar_hrd == htons(1)
 197                     && arp->ar_pro == htons(ETH_TYPE_IP)
 198                     && arp->ar_hln == ETH_ADDR_LEN
 199                     && arp->ar_pln == 4) {
 200                 /* We only match on the lower 8 bits of the opcode. */
 201                 if (ntohs(arp->ar_op) <= 0xff) {
 202                     flow->nw_proto = ntohs(arp->ar_op);
 203                 }
 204
 205                 if ((flow->nw_proto == ARP_OP_REQUEST)
 206                         || (flow->nw_proto == ARP_OP_REPLY)) {
 207                     flow->nw_src = arp->ar_spa;
 208                     flow->nw_dst = arp->ar_tpa;
 209                 }
 210             }
 211         }
 212     }
 213     return retval;
 214 }
 215
 216 /* Extracts the flow stats for a packet.  The 'flow' and 'packet'
 217  * arguments must have been initialized through a call to flow_extract().
 218  */
 219 void
 220 flow_extract_stats(const flow_t *flow, struct ofpbuf *packet,
 221         struct odp_flow_stats *stats)
 222 {
 223     memset(stats, '\0', sizeof(*stats));
 224
 225     if ((flow->dl_type == htons(ETH_TYPE_IP)) && packet->l4) {
 226         struct ip_header *ip = packet->l3;
 227         stats->ip_tos = ip->ip_tos;
 228         if ((flow->nw_proto == IP_TYPE_TCP) && packet->l7) {
 229             struct tcp_header *tcp = packet->l4;
 230             stats->tcp_flags = TCP_FLAGS(tcp->tcp_ctl);
 231         }
 232     }
 233
 234     stats->n_bytes = packet->size;
 235     stats->n_packets = 1;
 236 }
 237
 238 /* The Open vSwitch datapath supports matching on ARP payloads, which
 239  * OpenFlow does not.  This function is identical to 'flow_to_match',
 240  * but does not hide the datapath's ability to match on ARP. */
 241 void
 242 flow_to_ovs_match(const flow_t *flow, uint32_t wildcards,
 243                   struct ofp_match *match)
 244 {
 245     match->wildcards = htonl(wildcards);
 246     match->in_port = htons(flow->in_port == ODPP_LOCAL ? OFPP_LOCAL
 247                            : flow->in_port);
 248     match->dl_vlan = flow->dl_vlan;
 249     memcpy(match->dl_src, flow->dl_src, ETH_ADDR_LEN);
 250     memcpy(match->dl_dst, flow->dl_dst, ETH_ADDR_LEN);
 251     match->dl_type = flow->dl_type;
 252     match->nw_src = flow->nw_src;
 253     match->nw_dst = flow->nw_dst;
 254     match->nw_proto = flow->nw_proto;
 255     match->tp_src = flow->tp_src;
 256     match->tp_dst = flow->tp_dst;
 257     match->pad = 0;
 258 }
 259
 260 /* Extract 'flow' with 'wildcards' into the OpenFlow match structure
 261  * 'match'. */
 262 void
 263 flow_to_match(const flow_t *flow, uint32_t wildcards, struct ofp_match *match)
 264 {
 265     flow_to_ovs_match(flow, wildcards, match);
 266
 267     /* The datapath supports matching on an ARP's opcode and IP addresses,
 268      * but OpenFlow does not.  We wildcard and zero out the appropriate
 269      * fields so that OpenFlow is unaware of our trickery. */
 270     if (flow->dl_type == htons(ETH_TYPE_ARP)) {
 271         wildcards |= (OFPFW_NW_PROTO | OFPFW_NW_SRC_ALL | OFPFW_NW_DST_ALL);
 272         match->nw_src = 0;
 273         match->nw_dst = 0;
 274         match->nw_proto = 0;
 275     }
 276     match->wildcards = htonl(wildcards);
 277 }
 278
 279
 280 void
 281 flow_from_match(flow_t *flow, uint32_t *wildcards,
 282                 const struct ofp_match *match)
 283 {
 284     if (wildcards) {
 285         *wildcards = ntohl(match->wildcards);
 286
 287         /* The datapath supports matching on an ARP's opcode and IP addresses,
 288          * but OpenFlow does not.  In case the controller hasn't, we need to
 289          * set the appropriate wildcard bits so that we're externally
 290          * OpenFlow-compliant. */
 291         if (match->dl_type == htons(ETH_TYPE_ARP)) {
 292             *wildcards |= OFPFW_NW_PROTO | OFPFW_NW_SRC_ALL | OFPFW_NW_DST_ALL;
 293         }
 294     }
 295
 296     flow->nw_src = match->nw_src;
 297     flow->nw_dst = match->nw_dst;
 298     flow->in_port = (match->in_port == htons(OFPP_LOCAL) ? ODPP_LOCAL
 299                      : ntohs(match->in_port));
 300     flow->dl_vlan = match->dl_vlan;
 301     flow->dl_type = match->dl_type;
 302     flow->tp_src = match->tp_src;
 303     flow->tp_dst = match->tp_dst;
 304     memcpy(flow->dl_src, match->dl_src, ETH_ADDR_LEN);
 305     memcpy(flow->dl_dst, match->dl_dst, ETH_ADDR_LEN);
 306     flow->nw_proto = match->nw_proto;
 307     flow->reserved = 0;
 308 }
 309
 310 char *
 311 flow_to_string(const flow_t *flow)
 312 {
 313     struct ds ds = DS_EMPTY_INITIALIZER;
 314     flow_format(&ds, flow);
 315     return ds_cstr(&ds);
 316 }
 317
 318 void
 319 flow_format(struct ds *ds, const flow_t *flow)
 320 {
 321     ds_put_format(ds, "in_port%04x:vlan%d mac"ETH_ADDR_FMT"->"ETH_ADDR_FMT" "
 322                   "type%04x proto%"PRId8" ip"IP_FMT"->"IP_FMT" port%d->%d",
 323                   flow->in_port, ntohs(flow->dl_vlan),
 324                   ETH_ADDR_ARGS(flow->dl_src), ETH_ADDR_ARGS(flow->dl_dst),
 325                   ntohs(flow->dl_type), flow->nw_proto,
 326                   IP_ARGS(&flow->nw_src), IP_ARGS(&flow->nw_dst),
 327                   ntohs(flow->tp_src), ntohs(flow->tp_dst));
 328 }
 329
 330 void
 331 flow_print(FILE *stream, const flow_t *flow)
 332 {
 333     char *s = flow_to_string(flow);
 334     fputs(s, stream);
 335     free(s);
 336 }