lib/flow.c

   1 #include <sys/types.h>
   2 #include "flow.h"
   3 #include <inttypes.h>
   4 #include <netinet/in.h>
   5 #include <string.h>
   6 #include "buffer.h"
   7 #include "hash.h"
   8 #include "ip.h"
   9 #include "mac.h"
  10 #include "openflow.h"
  11 #include "packets.h"
  12
  13 #include "vlog.h"
  14 #define THIS_MODULE VLM_flow
  15
  16 void
  17 flow_extract(struct buffer *packet, uint16_t in_port, struct flow *flow)
  18 {
  19     struct buffer b = *packet;
  20     struct eth_header *eth;
  21
  22     if (b.size < ETH_TOTAL_MIN) {
  23         VLOG_WARN("packet length %d less than minimum size %d",
  24                   b.size, ETH_TOTAL_MIN);
  25     }
  26
  27     memset(flow, 0, sizeof *flow);
  28     flow->in_port = htons(in_port);
  29
  30     packet->l2 = b.data;
  31     packet->l3 = NULL;
  32     packet->l4 = NULL;
  33
  34     eth = buffer_at(&b, 0, sizeof *eth);
  35     if (eth) {
  36         buffer_pull(&b, ETH_HEADER_LEN);
  37         if (ntohs(eth->eth_type) >= OFP_DL_TYPE_ETH2_CUTOFF) {
  38             /* This is an Ethernet II frame */
  39             flow->dl_type = eth->eth_type;
  40         } else {
  41             /* This is an 802.2 frame */
  42             struct llc_snap_header *h = buffer_at(&b, 0, sizeof *h);
  43             if (h == NULL) {
  44                 return;
  45             }
  46             if (h->llc.llc_dsap == LLC_DSAP_SNAP
  47                 && h->llc.llc_ssap == LLC_SSAP_SNAP
  48                 && h->llc.llc_cntl == LLC_CNTL_SNAP
  49                 && !memcmp(h->snap.snap_org, SNAP_ORG_ETHERNET,
  50                            sizeof h->snap.snap_org)) {
  51                 flow->dl_type = h->snap.snap_type;
  52                 buffer_pull(&b, sizeof *h);
  53             } else {
  54                 flow->dl_type = OFP_DL_TYPE_NOT_ETH_TYPE;
  55                 buffer_pull(&b, sizeof(struct llc_header));
  56             }
  57         }
  58
  59         /* Check for a VLAN tag */
  60         if (flow->dl_type != htons(ETH_TYPE_VLAN)) {
  61             flow->dl_vlan = htons(OFP_VLAN_NONE);
  62         } else {
  63             struct vlan_header *vh = buffer_at(&b, 0, sizeof *vh);
  64             flow->dl_type = vh->vlan_next_type;
  65             flow->dl_vlan = vh->vlan_tci & htons(VLAN_VID);
  66             buffer_pull(&b, sizeof *vh);
  67         }
  68         memcpy(flow->dl_src, eth->eth_src, ETH_ADDR_LEN);
  69         memcpy(flow->dl_dst, eth->eth_dst, ETH_ADDR_LEN);
  70
  71         packet->l3 = b.data;
  72         if (flow->dl_type == htons(ETH_TYPE_IP)) {
  73             const struct ip_header *nh = buffer_at(&b, 0, sizeof *nh);
  74             if (nh) {
  75                 int ip_len = IP_IHL(nh->ip_ihl_ver) * 4;
  76                 if (ip_len < IP_HEADER_LEN) {
  77                     return;
  78                 }
  79
  80                 flow->nw_src = nh->ip_src;
  81                 flow->nw_dst = nh->ip_dst;
  82                 flow->nw_proto = nh->ip_proto;
  83                 if (flow->nw_proto == IP_TYPE_TCP
  84                     || flow->nw_proto == IP_TYPE_UDP) {
  85                     const struct udp_header *th;
  86                     th = packet->l4 = buffer_at(&b, ip_len, sizeof *th);
  87                     if (th) {
  88                         flow->tp_src = th->udp_src;
  89                         flow->tp_dst = th->udp_dst;
  90                     } else {
  91                         /* Avoid tricking other code into thinking that this
  92                          * packet has an L4 header. */
  93                         flow->nw_proto = 0;
  94                     }
  95                 }
  96             }
  97         } else if (flow->dl_type == htons(ETH_TYPE_ARP)) {
  98             const struct arp_eth_header *ah = buffer_at(&b, 0, sizeof *ah);
  99             if (ah && ah->ar_hrd == htons(ARP_HRD_ETHERNET)
 100                 && ah->ar_pro == htons(ARP_PRO_IP)
 101                 && ah->ar_hln == ETH_ADDR_LEN
 102                 && ah->ar_pln == sizeof flow->nw_src)
 103             {
 104                 /* check if sha/tha match dl_src/dl_dst? */
 105                 flow->nw_src = ah->ar_spa;
 106                 flow->nw_dst = ah->ar_tpa;
 107             }
 108         }
 109     }
 110 }
 111
 112 void
 113 flow_print(FILE *stream, const struct flow *flow)
 114 {
 115     fprintf(stream,
 116             "port%04x:vlan%04x mac"MAC_FMT"->"MAC_FMT" "
 117             "proto%04x ip"IP_FMT"->"IP_FMT" port%d->%d",
 118             ntohs(flow->in_port), ntohs(flow->dl_vlan),
 119             MAC_ARGS(flow->dl_src), MAC_ARGS(flow->dl_dst),
 120             ntohs(flow->dl_type),
 121             IP_ARGS(&flow->nw_src), IP_ARGS(&flow->nw_dst),
 122             ntohs(flow->tp_src), ntohs(flow->tp_dst));
 123 }
 124
 125 int
 126 flow_compare(const struct flow *a, const struct flow *b)
 127 {
 128     return memcmp(a, b, sizeof *a);
 129 }
 130
 131 unsigned long int
 132 flow_hash(const struct flow *flow, uint32_t basis)
 133 {
 134     return hash_fnv(flow, sizeof *flow, basis);
 135 }