text: /* Copyright (c) 2008 The Board of Trustees of The Leland Stanford
   * Junior University
   *
   * We are making the OpenFlow specification and associated documentation
   * (Software) available for public use and benefit with the expectation
   * that others will use, modify and enhance the Software and contribute
   * those enhancements back to the community. However, since we would
   * like to make the Software available for broadest use, with as few
   * restrictions as possible permission is hereby granted, free of
   * charge, to any person obtaining a copy of this Software to deal in
   * the Software under the copyrights without restriction, including
   * without limitation the rights to use, copy, modify, merge, publish,
   * distribute, sublicense, and/or sell copies of the Software, and to
   * permit persons to whom the Software is furnished to do so, subject to
   * the following conditions:
   *
   * The above copyright notice and this permission notice shall be
   * included in all copies or substantial portions of the Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
   * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
   * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
   * NONINFRINGEMENT.  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
   * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
   * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
   * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
   * SOFTWARE.
   *
   * The name and trademarks of copyright holder(s) may NOT be used in
   * advertising or publicity pertaining to the Software or any
   * derivatives without specific, written prior permission.
   */
  
  #include <config.h>
  #include "learning-switch.h"
  
  #include <errno.h>
  #include <inttypes.h>
  #include <netinet/in.h>
  #include <stdlib.h>
  #include <time.h>
  
  #include "flow.h"
  #include "mac-learning.h"
  #include "ofpbuf.h"
  #include "ofp-print.h"
  #include "openflow/openflow.h"
  #include "poll-loop.h"
  #include "queue.h"
  #include "rconn.h"
  #include "stp.h"
  #include "timeval.h"
  #include "vconn.h"
  #include "xtoxll.h"
  
  #define THIS_MODULE VLM_learning_switch
  #include "vlog.h"
  
  enum port_state {
      P_DISABLED = 1 << 0,
      P_LISTENING = 1 << 1,
      P_LEARNING = 1 << 2,
      P_FORWARDING = 1 << 3,
      P_BLOCKING = 1 << 4
  };
  
  struct lswitch {
      /* If nonnegative, the switch sets up flows that expire after the given
       * number of seconds (or never expire, if the value is OFP_FLOW_PERMANENT).
       * Otherwise, the switch processes every packet. */
      int max_idle;
  
      unsigned long long int datapath_id;
      uint32_t capabilities;
      time_t last_features_request;
      struct mac_learning *ml;    /* NULL to act as hub instead of switch. */
  
      /* Number of outgoing queued packets on the rconn. */
      int n_queued;
  
      /* Spanning tree protocol implementation.
       *
       * We implement STP states by, whenever a port's STP state changes,
       * querying all the flows on the switch and then deleting any of them that
       * are inappropriate for a port's STP state. */
      long long int next_query;   /* Next time at which to query all flows. */
      long long int last_query;   /* Last time we sent a query. */
      long long int last_reply;   /* Last time we received a query reply. */
      unsigned int port_states[STP_MAX_PORTS];
      uint32_t query_xid;         /* XID used for query. */
      int n_flows, n_no_recv, n_no_send;
  };
  
  /* The log messages here could actually be useful in debugging, so keep the
   * rate limit relatively high. */
  static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(30, 300);
  
  static void queue_tx(struct lswitch *, struct rconn *, struct ofpbuf *);
  static void send_features_request(struct lswitch *, struct rconn *);
  static void schedule_query(struct lswitch *, long long int delay);
  static bool may_learn(const struct lswitch *, uint16_t port_no);
  static bool may_recv(const struct lswitch *, uint16_t port_no,
                       bool any_actions);
  static bool may_send(const struct lswitch *, uint16_t port_no);
  
  typedef void packet_handler_func(struct lswitch *, struct rconn *, void *);
  static packet_handler_func process_switch_features;
  static packet_handler_func process_packet_in;
  static packet_handler_func process_echo_request;
  static packet_handler_func process_port_status;
  static packet_handler_func process_phy_port;
  static packet_handler_func process_stats_reply;
  
  /* Creates and returns a new learning switch.
   *
   * If 'learn_macs' is true, the new switch will learn the ports on which MAC
   * addresses appear.  Otherwise, the new switch will flood all packets.
   *
   * If 'max_idle' is nonnegative, the new switch will set up flows that expire
   * after the given number of seconds (or never expire, if 'max_idle' is
   * OFP_FLOW_PERMANENT).  Otherwise, the new switch will process every packet.
   *
   * 'rconn' is used to send out an OpenFlow features request. */
  struct lswitch *
  lswitch_create(struct rconn *rconn, bool learn_macs, int max_idle)
  {
      struct lswitch *sw;
      size_t i;
  
      sw = xcalloc(1, sizeof *sw);
      sw->max_idle = max_idle;
      sw->datapath_id = 0;
      sw->last_features_request = time_now() - 1;
      sw->ml = learn_macs ? mac_learning_create() : NULL;
      sw->next_query = LLONG_MIN;
      sw->last_query = LLONG_MIN;
      sw->last_reply = LLONG_MIN;
      for (i = 0; i < STP_MAX_PORTS; i++) {
          sw->port_states[i] = P_DISABLED;
      }
      send_features_request(sw, rconn);
      return sw;
  }
  
  /* Destroys 'sw'. */
  void
  lswitch_destroy(struct lswitch *sw)
  {
      if (sw) {
          mac_learning_destroy(sw->ml);
          free(sw);
      }
  }
  
  /* Takes care of necessary 'sw' activity, except for receiving packets (which
   * the caller must do). */
  void
  lswitch_run(struct lswitch *sw, struct rconn *rconn)
  {
      long long int now = time_msec();
  
      /* If we're waiting for more replies, keeping waiting for up to 10 s. */
      if (sw->last_reply != LLONG_MIN) {
          if (now - sw->last_reply > 10000) {
              VLOG_ERR_RL(&rl, "%012llx: No more flow stat replies last 10 s",
                          sw->datapath_id);
              sw->last_reply = LLONG_MIN;
              sw->last_query = LLONG_MIN;
              schedule_query(sw, 0);
          } else {
              return;
          }
      }
  
      /* If we're waiting for any reply at all, keep waiting for up to 10 s. */
      if (sw->last_query != LLONG_MIN) {
          if (now - sw->last_query > 10000) {
              VLOG_ERR_RL(&rl, "%012llx: No flow stat replies in last 10 s",
                          sw->datapath_id);
              sw->last_query = LLONG_MIN;
              schedule_query(sw, 0);
          } else {
              return;
          }
      }
  
      /* If it's time to send another query, do so. */
      if (sw->next_query != LLONG_MIN && now >= sw->next_query) {
          sw->next_query = LLONG_MIN;
          if (!rconn_is_connected(rconn)) {
              schedule_query(sw, 1000);
          } else {
              struct ofp_stats_request *osr;
              struct ofp_flow_stats_request *ofsr;
              struct ofpbuf *b;
              int error;
  
              VLOG_DBG("%012llx: Sending flow stats request to implement STP",
                       sw->datapath_id);
  
              sw->last_query = now;
              sw->query_xid = random_uint32();
              sw->n_flows = 0;
              sw->n_no_recv = 0;
              sw->n_no_send = 0;
              osr = make_openflow_xid(sizeof *osr + sizeof *ofsr,
                                      OFPT_STATS_REQUEST, sw->query_xid, &b);
              osr->type = htons(OFPST_FLOW);
              osr->flags = htons(0);
              ofsr = (struct ofp_flow_stats_request *) osr->body;
              ofsr->match.wildcards = htonl(OFPFW_ALL);
              ofsr->table_id = 0xff;
  
              error = rconn_send(rconn, b, NULL);
              if (error) {
                  VLOG_WARN_RL(&rl, "%012llx: sending flow stats request "
                               "failed: %s", sw->datapath_id, strerror(error));
                  ofpbuf_delete(b);
                  schedule_query(sw, 1000);
              }
          }
      }
  }
  
  static void
  wait_timeout(long long int started)
  {
      long long int now = time_msec();
      long long int timeout = 10000 - (now - started);
      if (timeout <= 0) {
          poll_immediate_wake();
      } else {
          poll_timer_wait(timeout);
      }
  }
  
  void
  lswitch_wait(struct lswitch *sw)
  {
      if (sw->last_reply != LLONG_MIN) {
          wait_timeout(sw->last_reply);
      } else if (sw->last_query != LLONG_MIN) {
          wait_timeout(sw->last_query);
      }
  }
  
  /* Processes 'msg', which should be an OpenFlow received on 'rconn', according
   * to the learning switch state in 'sw'.  The most likely result of processing
   * is that flow-setup and packet-out OpenFlow messages will be sent out on
   * 'rconn'.  */
  void
  lswitch_process_packet(struct lswitch *sw, struct rconn *rconn,
                         const struct ofpbuf *msg)
  {
      struct processor {
          uint8_t type;
          size_t min_size;
          packet_handler_func *handler;
      };
      static const struct processor processors[] = {
          {
              OFPT_ECHO_REQUEST,
              sizeof(struct ofp_header),
              process_echo_request
          },
          {
              OFPT_FEATURES_REPLY,
              sizeof(struct ofp_switch_features),
              process_switch_features
          },
          {
              OFPT_PACKET_IN,
              offsetof(struct ofp_packet_in, data),
              process_packet_in
          },
          {
              OFPT_PORT_STATUS,
              sizeof(struct ofp_port_status),
              process_port_status
          },
          {
              OFPT_STATS_REPLY,
              offsetof(struct ofp_stats_reply, body),
              process_stats_reply
          },
          {
              OFPT_FLOW_EXPIRED,
              sizeof(struct ofp_flow_expired),
              NULL
          },
      };
      const size_t n_processors = ARRAY_SIZE(processors);
      const struct processor *p;
      struct ofp_header *oh;
  
      oh = msg->data;
      if (sw->datapath_id == 0
          && oh->type != OFPT_ECHO_REQUEST
          && oh->type != OFPT_FEATURES_REPLY) {
          send_features_request(sw, rconn);
          return;
      }
  
      for (p = processors; p < &processors[n_processors]; p++) {
          if (oh->type == p->type) {
              if (msg->size < p->min_size) {
                  VLOG_WARN_RL(&rl, "%012llx: %s: too short (%zu bytes) for "
                               "type %"PRIu8" (min %zu)", sw->datapath_id,
                               rconn_get_name(rconn), msg->size, oh->type,
                               p->min_size);
                  return;
              }
              if (p->handler) {
                  (p->handler)(sw, rconn, msg->data);
              }
              return;
          }
      }
      if (VLOG_IS_DBG_ENABLED()) {
          char *p = ofp_to_string(msg->data, msg->size, 2);
          VLOG_DBG_RL(&rl, "%012llx: OpenFlow packet ignored: %s",
                      sw->datapath_id, p);
          free(p);
      }
  }
  
  static void
  send_features_request(struct lswitch *sw, struct rconn *rconn)
  {
      time_t now = time_now();
      if (now >= sw->last_features_request + 1) {
          struct ofpbuf *b;
          struct ofp_switch_config *osc;
  
          /* Send OFPT_FEATURES_REQUEST. */
          make_openflow(sizeof(struct ofp_header), OFPT_FEATURES_REQUEST, &b);
          queue_tx(sw, rconn, b);
  
          /* Send OFPT_SET_CONFIG. */
          osc = make_openflow(sizeof *osc, OFPT_SET_CONFIG, &b);
          osc->flags = htons(OFPC_SEND_FLOW_EXP);
          osc->miss_send_len = htons(OFP_DEFAULT_MISS_SEND_LEN);
          queue_tx(sw, rconn, b);
  
          sw->last_features_request = now;
      }
  }
  
  static void
  queue_tx(struct lswitch *sw, struct rconn *rconn, struct ofpbuf *b)
  {
      int retval = rconn_send_with_limit(rconn, b, &sw->n_queued, 10);
      if (retval && retval != ENOTCONN) {
          if (retval == EAGAIN) {
              VLOG_WARN_RL(&rl, "%012llx: %s: tx queue overflow",
                           sw->datapath_id, rconn_get_name(rconn));
          } else {
              VLOG_WARN_RL(&rl, "%012llx: %s: send: %s",
                           sw->datapath_id, rconn_get_name(rconn),
                           strerror(retval));
          }
      }
  }
  
  static void
  schedule_query(struct lswitch *sw, long long int delay)
  {
      long long int now = time_msec();
      if (sw->next_query == LLONG_MIN || sw->next_query > now + delay) {
          sw->next_query = now + delay;
      }
  }
  
  static void
  process_switch_features(struct lswitch *sw, struct rconn *rconn, void *osf_)
  {
      struct ofp_switch_features *osf = osf_;
      size_t n_ports = ((ntohs(osf->header.length)
                         - offsetof(struct ofp_switch_features, ports))
                        / sizeof *osf->ports);
      size_t i;
  
      sw->datapath_id = ntohll(osf->datapath_id);
      sw->capabilities = ntohl(osf->capabilities);
      for (i = 0; i < n_ports; i++) {
          process_phy_port(sw, rconn, &osf->ports[i]);
      }
      if (sw->capabilities & OFPC_STP) {
          schedule_query(sw, 1000);
      }
  }
  
  static void
  process_packet_in(struct lswitch *sw, struct rconn *rconn, void *opi_)
  {
      struct ofp_packet_in *opi = opi_;
      uint16_t in_port = ntohs(opi->in_port);
      uint16_t out_port = OFPP_FLOOD;
  
      size_t pkt_ofs, pkt_len;
      struct ofpbuf pkt;
      struct flow flow;
  
      /* Extract flow data from 'opi' into 'flow'. */
      pkt_ofs = offsetof(struct ofp_packet_in, data);
      pkt_len = ntohs(opi->header.length) - pkt_ofs;
      pkt.data = opi->data;
      pkt.size = pkt_len;
      flow_extract(&pkt, in_port, &flow);
  
      if (may_learn(sw, in_port) && sw->ml) {
          if (mac_learning_learn(sw->ml, flow.dl_src, in_port)) {
              VLOG_DBG_RL(&rl, "%012llx: learned that "ETH_ADDR_FMT" is on "
                          "port %"PRIu16, sw->datapath_id,
                          ETH_ADDR_ARGS(flow.dl_src), in_port);
          }
      }
  
      if (!may_recv(sw, in_port, false)) {
          /* STP prevents receiving anything on this port. */
          goto drop_it;
      }
  
      if (sw->ml) {
          uint16_t learned_port = mac_learning_lookup(sw->ml, flow.dl_dst);
          if (may_send(sw, learned_port)) {
              out_port = learned_port;
          }
      }
  
      if (in_port == out_port) {
          /* Don't send out packets on their input ports. */
          goto drop_it;
      } else if (sw->max_idle >= 0 && (!sw->ml || out_port != OFPP_FLOOD)) {
          /* The output port is known, or we always flood everything, so add a
           * new flow. */
          queue_tx(sw, rconn, make_add_simple_flow(&flow, ntohl(opi->buffer_id),
                                                   out_port, sw->max_idle));
  
          /* If the switch didn't buffer the packet, we need to send a copy. */
          if (ntohl(opi->buffer_id) == UINT32_MAX) {
              queue_tx(sw, rconn,
                       make_unbuffered_packet_out(&pkt, in_port, out_port));
          }
      } else {
          /* We don't know that MAC, or we don't set up flows.  Send along the
           * packet without setting up a flow. */
          struct ofpbuf *b;
          if (ntohl(opi->buffer_id) == UINT32_MAX) {
              b = make_unbuffered_packet_out(&pkt, in_port, out_port);
          } else {
              b = make_buffered_packet_out(ntohl(opi->buffer_id),
                                           in_port, out_port);
          }
          queue_tx(sw, rconn, b);
      }
      return;
  
  drop_it:
      /* Set up a flow to drop packets, or just drop the packet if we don't set
       * up flows at all. */
      if (sw->max_idle >= 0) {
          queue_tx(sw, rconn, make_add_flow(&flow, ntohl(opi->buffer_id),
                                            sw->max_idle, 0));
      }
      return;
  }
  
  static void
  process_echo_request(struct lswitch *sw, struct rconn *rconn, void *rq_)
  {
      struct ofp_header *rq = rq_;
      queue_tx(sw, rconn, make_echo_reply(rq));
  }
  
  static void
  process_port_status(struct lswitch *sw, struct rconn *rconn, void *ops_)
  {
      struct ofp_port_status *ops = ops_;
      process_phy_port(sw, rconn, &ops->desc);
  }
  
  static void
  process_phy_port(struct lswitch *sw, struct rconn *rconn, void *opp_)
  {
      const struct ofp_phy_port *opp = opp_;
      uint16_t port_no = ntohs(opp->port_no);
      if (sw->capabilities & OFPC_STP && port_no < STP_MAX_PORTS) {
          uint32_t config = ntohl(opp->config);
          uint32_t state = ntohl(opp->state);
          unsigned int *port_state = &sw->port_states[port_no];
          unsigned int new_port_state;
  
          if (!(config & (OFPPC_NO_STP | OFPPC_PORT_DOWN))
              && !(state & OFPPS_LINK_DOWN))
          {
              switch (state & OFPPS_STP_MASK) {
              case OFPPS_STP_LISTEN:
                  new_port_state = P_LISTENING;
                  break;
              case OFPPS_STP_LEARN:
                  new_port_state = P_LEARNING;
                  break;
              case OFPPS_STP_FORWARD:
                  new_port_state = P_FORWARDING;
                  break;
              case OFPPS_STP_BLOCK:
                  new_port_state = P_BLOCKING;
                  break;
              default:
                  new_port_state = P_DISABLED;
                  break;
              }
          } else {
              new_port_state = P_FORWARDING;
          }
          if (*port_state != new_port_state) {
              *port_state = new_port_state;
              schedule_query(sw, 1000);
          }
      }
  }
  
  static unsigned int
  get_port_state(const struct lswitch *sw, uint16_t port_no)
  {
      return (port_no >= STP_MAX_PORTS || !(sw->capabilities & OFPC_STP)
              ? P_FORWARDING
              : sw->port_states[port_no]);
  }
  
  static bool
  may_learn(const struct lswitch *sw, uint16_t port_no)
  {
      return get_port_state(sw, port_no) & (P_LEARNING | P_FORWARDING);
  }
  
  static bool
  may_recv(const struct lswitch *sw, uint16_t port_no, bool any_actions)
  {
      unsigned int state = get_port_state(sw, port_no);
      return !(any_actions
               ? state & (P_DISABLED | P_LISTENING | P_BLOCKING)
               : state & (P_DISABLED | P_LISTENING | P_BLOCKING | P_LEARNING));
  }
  
  static bool
  may_send(const struct lswitch *sw, uint16_t port_no)
  {
      return get_port_state(sw, port_no) & P_FORWARDING;
  }
  
  static void
  process_flow_stats(struct lswitch *sw, struct rconn *rconn,
                     const struct ofp_flow_stats *ofs)
  {
      const char *end = (char *) ofs + ntohs(ofs->length);
      bool delete = false;
  
      /* Decide to delete the flow if it matches on an STP-disabled physical
       * port.  But don't delete it if the flow just drops all received packets,
       * because that's a perfectly reasonable thing to do for disabled physical
       * ports. */
      if (!(ofs->match.wildcards & htonl(OFPFW_IN_PORT))) {
          if (!may_recv(sw, ntohs(ofs->match.in_port),
                        end > (char *) ofs->actions)) {
              delete = true;
              sw->n_no_recv++;
          }
      }
  
      /* Decide to delete the flow if it forwards to an STP-disabled physical
       * port. */
      if (!delete) {
          const struct ofp_action_header *a;
          size_t len;
  
          for (a = ofs->actions; (char *) a < end; a += len / 8) {
              uint16_t type;
  
              len = ntohs(a->len);
              if (len > end - (char *) a) {
                  VLOG_DBG_RL(&rl, "%012llx: action exceeds available space "
                              "(%zu > %td)",
                              sw->datapath_id, len, end - (char *) a);
                  break;
              } else if (len % 8) {
                  VLOG_DBG_RL(&rl, "%012llx: action length (%zu) not multiple "
                              "of 8 bytes", sw->datapath_id, len);
                  break;
              }
  
              type = ntohs(a->type);
              if (a->type == htons(OFPAT_OUTPUT)) {
                  struct ofp_action_output *oao = (struct ofp_action_output *) a;
                  if (!may_send(sw, ntohs(oao->port))) {
                      delete = true;
                      sw->n_no_send++;
                      break;
                  }
              }
          }
      }
  
      /* Delete the flow. */
      if (delete) {
          struct ofp_flow_mod *ofm;
          struct ofpbuf *b;
  
          ofm = make_openflow(offsetof(struct ofp_flow_mod, actions),
                              OFPT_FLOW_MOD, &b);
          ofm->match = ofs->match;
          ofm->command = OFPFC_DELETE_STRICT;
          rconn_send(rconn, b, NULL);
      }
  }
  
  static void
  process_stats_reply(struct lswitch *sw, struct rconn *rconn, void *osr_)
  {
      struct ofp_stats_reply *osr = osr_;
      const uint8_t *body = osr->body;
      const uint8_t *pos = body;
      size_t body_len;
  
      if (sw->last_query == LLONG_MIN
          || osr->type != htons(OFPST_FLOW)
          || osr->header.xid != sw->query_xid) {
          return;
      }
      body_len = (ntohs(osr->header.length)
                  - offsetof(struct ofp_stats_reply, body));
      for (;;) {
          const struct ofp_flow_stats *fs;
          ptrdiff_t bytes_left = body + body_len - pos;
          size_t length;
  
          if (bytes_left < sizeof *fs) {
              if (bytes_left != 0) {
                  VLOG_WARN_RL(&rl, "%012llx: %td leftover bytes in flow "
                               "stats reply", sw->datapath_id, bytes_left);
              }
              break;
          }
  
          fs = (const void *) pos;
          length = ntohs(fs->length);
          if (length < sizeof *fs) {
              VLOG_WARN_RL(&rl, "%012llx: flow stats length %zu is shorter than "
                           "min %zu", sw->datapath_id, length, sizeof *fs);
              break;
          } else if (length > bytes_left) {
              VLOG_WARN_RL(&rl, "%012llx: flow stats length %zu but only %td "
                           "bytes left", sw->datapath_id, length, bytes_left);
              break;
          } else if ((length - sizeof *fs) % sizeof fs->actions[0]) {
              VLOG_WARN_RL(&rl, "%012llx: flow stats length %zu has %zu bytes "
                           "left over in final action", sw->datapath_id, length,
                           (length - sizeof *fs) % sizeof fs->actions[0]);
              break;
          }
  
          sw->n_flows++;
          process_flow_stats(sw, rconn, fs);
  
          pos += length;
       }
      if (!(osr->flags & htons(OFPSF_REPLY_MORE))) {
          VLOG_DBG("%012llx: Deleted %d of %d received flows to "
                   "implement STP, %d because of no-recv, %d because of "
                   "no-send", sw->datapath_id,
                   sw->n_no_recv + sw->n_no_send, sw->n_flows,
                   sw->n_no_recv, sw->n_no_send);
          sw->last_query = LLONG_MIN;
          sw->last_reply = LLONG_MIN;
      } else {
          sw->last_reply = time_msec();
      }
  }
  
  