// SPDX-License-Identifier: BSD-2-Clause
module frr-bfdd {
  yang-version 1.1;
  namespace "http://frrouting.org/yang/bfdd";
  prefix frr-bfdd;

  import ietf-inet-types {
    prefix inet;
  }
  import ietf-yang-types {
    prefix yang;
  }
  import frr-interface {
    prefix frr-interface;
  }
  import frr-vrf {
    prefix frr-vrf;
  }
  import frr-route-types {
    prefix frr-route-types;
  }

  organization "FRRouting";
  contact
    "FRR Users List:       <mailto:frog@lists.frrouting.org>
     FRR Development List: <mailto:dev@lists.frrouting.org>";
  description
    "This module defines a model for managing FRR bfdd daemon.

     Copyright 2020 FRRouting

     Redistribution and use in source and binary forms, with or without
     modification, are permitted provided that the following conditions
     are met:

     1. Redistributions of source code must retain the above copyright notice,
     this list of conditions and the following disclaimer.

     2. Redistributions in binary form must reproduce the above copyright
     notice, this list of conditions and the following disclaimer in the
     documentation and/or other materials provided with the distribution.

     THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     \"AS IS\" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
     A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
     HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
     LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.";

  revision 2019-05-09 {
    description "Initial revision.";
    reference
      "RFC 5880: Bidirectional Forwarding Detection (BFD).
       RFC 5881: Bidirectional Forwarding Detection (BFD)
                 for IPv4 and IPv6 (Single Hop).
       RFC 5883: Bidirectional Forwarding Detection (BFD) for Multihop Paths.";
  }


  /*
   * BFD types declaration.
   */
  typedef multiplier {
    description "Detection multiplier";
    type uint8 {
      range "2..255";
    }
  }

  typedef discriminator {
    description "BFD session identification";
    type uint32 {
      range "1..4294967295";
    }
  }

  typedef state {
    description "BFD session state";
    type enumeration {
      enum admin-down {
        value 0;
        description "Administratively down";
      }
      enum down {
        value 1;
        description "Down";
      }
      enum init {
        value 2;
        description "Initializing";
      }
      enum up {
        value 3;
        description "Up";
      }
    }
  }

  typedef diagnostic {
    description "BFD session diagnostic";
    type enumeration {
      enum ok {
        value 0;
        description "Ok";
      }
      enum control-expired {
        value 1;
        description "Control timer expired";
      }
      enum echo-failed {
        value 2;
        description "Echo function failed";
      }
      enum neighbor-down {
        value 3;
        description "Neighbor signaled session down";
      }
      enum forwarding-reset {
        value 4;
        description "Forwarding plane reset";
      }
      enum path-down {
        value 5;
        description "Path down";
      }
      enum concatenated-path-down {
        value 6;
        description "Concatenated path down";
      }
      enum administratively-down {
        value 7;
        description "Administratively down";
      }
      enum reverse-concat-path-down {
        value 8;
        description "Reverse concatenated path down";
      }
    }
  }

  typedef profile-name {
    type string {
      length "1..64";
    }
    description "Profile name format";
  }

  typedef profile-ref {
    type leafref {
      path "/frr-bfdd:bfdd/frr-bfdd:bfd/frr-bfdd:profile/frr-bfdd:name";
      require-instance false;
    }
    description "Reference to a BFD profile";
  }

  /*
   * Shared BFD items.
   */
  grouping session-common {
    description "Common BFD session settings";

    leaf detection-multiplier {
      type multiplier;
      default 3;
      description "Local session detection multiplier";
    }

    leaf desired-transmission-interval {
      type uint32 {
          range "10000..60000000";
      }
      units microseconds;
      default 300000;
      description "Minimum desired control packet transmission interval";
    }

    leaf required-receive-interval {
      type uint32 {
          range "10000..60000000";
      }
      units microseconds;
      default 300000;
      description "Minimum required control packet receive interval";
    }

    leaf administrative-down {
      type boolean;
      default false;
      description "Disables or enables the session administratively";
    }

    leaf passive-mode {
      type boolean;
      default false;
      description
        "Don't attempt to start session establishment.";
    }
  }

  grouping session-echo {
    description "BFD session echo settings";

    leaf echo-mode {
      type boolean;
      default false;
      description "Use echo packets to detect failures";
    }

    leaf desired-echo-transmission-interval {
      type uint32 {
          range "10000..60000000";
      }
      units microseconds;
      default 50000;
      description "Minimum desired echo packet transmission interval";
    }

    leaf required-echo-receive-interval {
      type uint32 {
          range "0 | 10000..60000000";
      }
      units microseconds;
      default 50000;
      description "Minimum required echo packet receive interval";
    }
  }

  grouping session-multi-hop {
    description "BFD session multi hop settings.";

    leaf minimum-ttl {
      type uint8 {
        range "1..254";
      }
      default "254";
      description
        "Minimum expected TTL on received packets.";
    }
  }

  grouping bfd-monitoring {
    description
      "BFD monitoring template for protocol integration.";

    leaf source {
      type inet:ip-address;
      description
        "Source address to use for liveness check.

         When source is not set and multi-hop is `false` the source
         address will be `0.0.0.0` (any).

         When source is not set and multi-hop is `true` the source
         address will be automatic selected through Next Hop Tracking (NHT).";
    }

    leaf multi-hop {
      description
        "Use multi hop session instead of single hop.";
      type boolean;
      default false;
    }

    leaf profile {
      description
        "BFD pre configured profile.";
      type frr-bfdd:profile-ref;
    }
  }

  grouping session-states {
    /*
     * Local settings.
     */
    leaf local-discriminator {
      type discriminator;
      description "Local session identifier";
    }

    leaf local-state {
      type state;
      description "Local session state";
    }

    leaf local-diagnostic {
      type diagnostic;
      description "Local session diagnostic";
    }

    leaf local-multiplier {
      type multiplier;
      description "Local session current multiplier";
    }

    /*
     * Remote settings.
     */
    leaf remote-discriminator {
      type discriminator;
      description "Remote session identifier";
    }

    leaf remote-state {
      type state;
      description "Remote session state";
    }

    leaf remote-diagnostic {
      type diagnostic;
      description "Local session diagnostic";
    }

    leaf remote-multiplier {
      type multiplier;
      description "Remote session detection multiplier";
    }

    /*
     * Negotiated settings.
     */
    leaf negotiated-transmission-interval {
      description "Negotiated transmit interval";
      type uint32;
      units microseconds;
    }

    leaf negotiated-receive-interval {
      description "Negotiated receive interval";
      type uint32;
      units microseconds;
    }

    leaf detection-mode {
      description "Detection mode";

      type enumeration {
        enum async-with-echo {
          value "1";
          description "Async with echo";
        }
        enum async-without-echo {
          value "2";
          description "Async without echo";
        }
        enum demand-with-echo {
          value "3";
          description "Demand with echo";
        }
        enum demand-without-echo {
          value "4";
          description "Demand without echo";
        }
      }
    }

    /*
     * Statistics.
     */
    leaf last-down-time {
      type yang:date-and-time;
      description "Time and date of the last time session was down";
    }

    leaf last-up-time {
      type yang:date-and-time;
      description "Time and date of the last time session was up";
    }

    leaf session-down-count {
      type uint32;
      description "Number of times the session went down";
    }

    leaf session-up-count {
      type uint32;
      description "Number of times the session went up";
    }

    leaf control-packet-input-count {
      type uint64;
      description "Number of control packets received";
    }

    leaf control-packet-output-count {
      type uint64;
      description "Number of control packets sent";
    }

    /*
     * Echo mode operational data.
     */
    leaf negotiated-echo-transmission-interval {
      type uint32;
      units microseconds;
      description "Negotiated echo transmit interval";
    }

    /*
     * Statistics.
     */
    leaf echo-packet-input-count {
      type uint64;
      description "Number of echo packets received";
    }

    leaf echo-packet-output-count {
      type uint64;
      description "Number of echo packets sent";
    }
  }

  /*
   * BFD operational.
   */
  container bfdd {
    container bfd {
      presence "Present if the BFD protocol is enabled";

      list profile {
        key "name";
        description "BFD pre configuration profiles";

        leaf name {
          type profile-name;
          description "Profile name";
        }

        uses session-common;
        uses session-echo;
        uses session-multi-hop;
      }

      container sessions {
        list single-hop {
          key "dest-addr interface vrf";
          description "List of single hop sessions";

          leaf dest-addr {
            type inet:ip-address;
            description "IP address of the peer";
          }

          leaf interface {
            type frr-interface:interface-ref;
            description "Interface to use to contact peer";
          }

          leaf vrf {
            type frr-vrf:vrf-ref;
            description "Virtual Routing Domain name";
          }

          leaf source-addr {
            type inet:ip-address;
            description "Local IP address";
          }

          leaf profile {
            type profile-ref;
            description "Override defaults with profile.";
          }

          uses session-common;
          uses session-echo;

          container stats {
            uses session-states;
            config false;
          }
        }

        list multi-hop {
          key "source-addr dest-addr vrf";
          description "List of multi hop sessions";

          leaf source-addr {
            type inet:ip-address;
            description "Local IP address";
          }

          leaf dest-addr {
            type inet:ip-address;
            description "IP address of the peer";
          }

          leaf vrf {
            type frr-vrf:vrf-ref;
            description "Virtual Routing Domain name";
          }

          leaf profile {
            type profile-ref;
            description "Override defaults with profile.";
          }

          uses session-common;
          uses session-multi-hop;

          container stats {
            uses session-states;
            config false;
          }
        }
      }
    }
  }
}