lib/flow.c

   1 /*
   2  * Copyright (c) 2008, 2009 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                 flow->dl_vlan_pcp = (ntohs(vh->vlan_tci) & 0xe000) >> 13;
 143             }
 144         }
 145         memcpy(flow->dl_src, eth->eth_src, ETH_ADDR_LEN);
 146         memcpy(flow->dl_dst, eth->eth_dst, ETH_ADDR_LEN);
 147
 148         packet->l3 = b.data;
 149         if (flow->dl_type == htons(ETH_TYPE_IP)) {
 150             const struct ip_header *nh = pull_ip(&b);
 151             if (nh) {
 152                 flow->nw_src = nh->ip_src;
 153                 flow->nw_dst = nh->ip_dst;
 154                 flow->nw_proto = nh->ip_proto;
 155                 packet->l4 = b.data;
 156                 if (!IP_IS_FRAGMENT(nh->ip_frag_off)) {
 157                     if (flow->nw_proto == IP_TYPE_TCP) {
 158                         const struct tcp_header *tcp = pull_tcp(&b);
 159                         if (tcp) {
 160                             flow->tp_src = tcp->tcp_src;
 161                             flow->tp_dst = tcp->tcp_dst;
 162                             packet->l7 = b.data;
 163                         } else {
 164                             /* Avoid tricking other code into thinking that
 165                              * this packet has an L4 header. */
 166                             flow->nw_proto = 0;
 167                         }
 168                     } else if (flow->nw_proto == IP_TYPE_UDP) {
 169                         const struct udp_header *udp = pull_udp(&b);
 170                         if (udp) {
 171                             flow->tp_src = udp->udp_src;
 172                             flow->tp_dst = udp->udp_dst;
 173                             packet->l7 = b.data;
 174                         } else {
 175                             /* Avoid tricking other code into thinking that
 176                              * this packet has an L4 header. */
 177                             flow->nw_proto = 0;
 178                         }
 179                     } else if (flow->nw_proto == IP_TYPE_ICMP) {
 180                         const struct icmp_header *icmp = pull_icmp(&b);
 181                         if (icmp) {
 182                             flow->icmp_type = htons(icmp->icmp_type);
 183                             flow->icmp_code = htons(icmp->icmp_code);
 184                             packet->l7 = b.data;
 185                         } else {
 186                             /* Avoid tricking other code into thinking that
 187                              * this packet has an L4 header. */
 188                             flow->nw_proto = 0;
 189                         }
 190                     }
 191                 } else {
 192                     retval = 1;
 193                 }
 194             }
 195         } else if (flow->dl_type == htons(ETH_TYPE_ARP)) {
 196             const struct arp_eth_header *arp = pull_arp(&b);
 197             if (arp && arp->ar_hrd == htons(1)
 198                     && arp->ar_pro == htons(ETH_TYPE_IP)
 199                     && arp->ar_hln == ETH_ADDR_LEN
 200                     && arp->ar_pln == 4) {
 201                 /* We only match on the lower 8 bits of the opcode. */
 202                 if (ntohs(arp->ar_op) <= 0xff) {
 203                     flow->nw_proto = ntohs(arp->ar_op);
 204                 }
 205
 206                 if ((flow->nw_proto == ARP_OP_REQUEST)
 207                         || (flow->nw_proto == ARP_OP_REPLY)) {
 208                     flow->nw_src = arp->ar_spa;
 209                     flow->nw_dst = arp->ar_tpa;
 210                 }
 211             }
 212         }
 213     }
 214     return retval;
 215 }
 216
 217 /* Extracts the flow stats for a packet.  The 'flow' and 'packet'
 218  * arguments must have been initialized through a call to flow_extract().
 219  */
 220 void
 221 flow_extract_stats(const flow_t *flow, struct ofpbuf *packet,
 222         struct odp_flow_stats *stats)
 223 {
 224     memset(stats, '\0', sizeof(*stats));
 225
 226     if ((flow->dl_type == htons(ETH_TYPE_IP)) && packet->l4) {
 227         struct ip_header *ip = packet->l3;
 228         stats->ip_tos = ip->ip_tos;
 229         if ((flow->nw_proto == IP_TYPE_TCP) && packet->l7) {
 230             struct tcp_header *tcp = packet->l4;
 231             stats->tcp_flags = TCP_FLAGS(tcp->tcp_ctl);
 232         }
 233     }
 234
 235     stats->n_bytes = packet->size;
 236     stats->n_packets = 1;
 237 }
 238
 239 /* The Open vSwitch datapath supports matching on ARP payloads, which
 240  * OpenFlow does not.  This function is identical to 'flow_to_match',
 241  * but does not hide the datapath's ability to match on ARP. */
 242 void
 243 flow_to_ovs_match(const flow_t *flow, uint32_t wildcards,
 244                   struct ofp_match *match)
 245 {
 246     match->wildcards = htonl(wildcards);
 247     match->in_port = htons(flow->in_port == ODPP_LOCAL ? OFPP_LOCAL
 248                            : flow->in_port);
 249     match->dl_vlan = flow->dl_vlan;
 250     match->dl_vlan_pcp = flow->dl_vlan_pcp;
 251     memcpy(match->dl_src, flow->dl_src, ETH_ADDR_LEN);
 252     memcpy(match->dl_dst, flow->dl_dst, ETH_ADDR_LEN);
 253     match->dl_type = flow->dl_type;
 254     match->nw_src = flow->nw_src;
 255     match->nw_dst = flow->nw_dst;
 256     match->nw_proto = flow->nw_proto;
 257     match->tp_src = flow->tp_src;
 258     match->tp_dst = flow->tp_dst;
 259     memset(match->pad1, '\0', sizeof match->pad1);
 260     memset(match->pad2, '\0', sizeof match->pad2);
 261 }
 262
 263 /* Extract 'flow' with 'wildcards' into the OpenFlow match structure
 264  * 'match'. */
 265 void
 266 flow_to_match(const flow_t *flow, uint32_t wildcards, struct ofp_match *match)
 267 {
 268     flow_to_ovs_match(flow, wildcards, match);
 269
 270     /* The datapath supports matching on an ARP's opcode and IP addresses,
 271      * but OpenFlow does not.  We wildcard and zero out the appropriate
 272      * fields so that OpenFlow is unaware of our trickery. */
 273     if (flow->dl_type == htons(ETH_TYPE_ARP)) {
 274         wildcards |= (OFPFW_NW_PROTO | OFPFW_NW_SRC_ALL | OFPFW_NW_DST_ALL);
 275         match->nw_src = 0;
 276         match->nw_dst = 0;
 277         match->nw_proto = 0;
 278     }
 279     match->wildcards = htonl(wildcards);
 280 }
 281
 282
 283 void
 284 flow_from_match(flow_t *flow, uint32_t *wildcards,
 285                 const struct ofp_match *match)
 286 {
 287     if (wildcards) {
 288         *wildcards = ntohl(match->wildcards);
 289     }
 290     /* The datapath supports matching on an ARP's opcode and IP addresses,
 291      * but OpenFlow does not.  In case the controller hasn't, we need to
 292      * set the appropriate wildcard bits so that we're externally
 293      * OpenFlow-compliant. */
 294     if (match->dl_type == htons(ETH_TYPE_ARP)) {
 295         *wildcards |= (OFPFW_NW_PROTO | OFPFW_NW_SRC_ALL | OFPFW_NW_DST_ALL);
 296     }
 297
 298     flow->nw_src = match->nw_src;
 299     flow->nw_dst = match->nw_dst;
 300     flow->in_port = (match->in_port == htons(OFPP_LOCAL) ? ODPP_LOCAL
 301                      : ntohs(match->in_port));
 302     flow->dl_vlan = match->dl_vlan;
 303     flow->dl_vlan_pcp = match->dl_vlan_pcp;
 304     flow->dl_type = match->dl_type;
 305     flow->tp_src = match->tp_src;
 306     flow->tp_dst = match->tp_dst;
 307     memcpy(flow->dl_src, match->dl_src, ETH_ADDR_LEN);
 308     memcpy(flow->dl_dst, match->dl_dst, ETH_ADDR_LEN);
 309     flow->nw_proto = match->nw_proto;
 310 }
 311
 312 char *
 313 flow_to_string(const flow_t *flow)
 314 {
 315     struct ds ds = DS_EMPTY_INITIALIZER;
 316     flow_format(&ds, flow);
 317     return ds_cstr(&ds);
 318 }
 319
 320 void
 321 flow_format(struct ds *ds, const flow_t *flow)
 322 {
 323     ds_put_format(ds, "in_port%04x:vlan%d:pcp%d mac"ETH_ADDR_FMT
 324                   "->"ETH_ADDR_FMT" type%04x proto%"PRId8" ip"IP_FMT
 325                   "->"IP_FMT" port%d->%d",
 326                   flow->in_port, ntohs(flow->dl_vlan), flow->dl_vlan_pcp,
 327                   ETH_ADDR_ARGS(flow->dl_src), ETH_ADDR_ARGS(flow->dl_dst),
 328                   ntohs(flow->dl_type), flow->nw_proto,
 329                   IP_ARGS(&flow->nw_src), IP_ARGS(&flow->nw_dst),
 330                   ntohs(flow->tp_src), ntohs(flow->tp_dst));
 331 }
 332
 333 void
 334 flow_print(FILE *stream, const flow_t *flow)
 335 {
 336     char *s = flow_to_string(flow);
 337     fputs(s, stream);
 338     free(s);
 339 }