module ietf-dots-signal-channel {

    yang-version 1.1;

    namespace
      "urn:ietf:params:xml:ns:yang:ietf-dots-signal-channel";

    prefix dots-signal;

    import ietf-inet-types {
      prefix inet;
      reference
        "Section 4 of RFC 6991";


    }
    import ietf-yang-types {
      prefix yang;
      reference
        "Section 3 of RFC 6991";


    }
    import ietf-dots-data-channel {
      prefix data-channel;
      reference
        "RFC 8783: Distributed Denial-of-Service Open Threat Signaling
        	  (DOTS) Data Channel Specification";


    }
    import iana-dots-signal-channel {
      prefix iana-dots-signal;
      reference
        "RFC 9132: Distributed Denial-of-Service Open Threat Signaling
        	  (DOTS) Signal Channel Specification";


    }
    import ietf-yang-structure-ext {
      prefix sx;
      reference
        "RFC 8791: YANG Data Structure Extensions";


    }

    organization
      "IETF DDoS Open Threat Signaling (DOTS) Working Group";

    contact
      "WG Web:   <https://datatracker.ietf.org/wg/dots/>
     WG List:  <mailto:dots@ietf.org>

     Editor:  Mohamed Boucadair
              <mailto:mohamed.boucadair@orange.com>

     Editor:  Jon Shallow
              <mailto:supjps-ietf@jpshallow.com>

     Author:  Konda, Tirumaleswar Reddy.K
              <mailto:kondtir@gmail.com>

     Author:  Prashanth Patil
              <mailto:praspati@cisco.com>

     Author:  Andrew Mortensen
              <mailto:amortensen@arbor.net>

     Author:  Nik Teague
              <mailto:nteague@ironmountain.co.uk>";

    description
      "This module contains YANG definition for the signaling
     messages exchanged between a DOTS client and a DOTS server.

     Copyright (c) 2021 IETF Trust and the persons identified as
     authors of the code.  All rights reserved.

     Redistribution and use in source and binary forms, with or
     without modification, is permitted pursuant to, and subject
     to the license terms contained in, the Simplified BSD License
     set forth in Section 4.c of the IETF Trust's Legal Provisions
     Relating to IETF Documents
     (http://trustee.ietf.org/license-info).

     This version of this YANG module is part of RFC 9132; see
     the RFC itself for full legal notices.";

    revision "2021-09-02" {
      description
        "Updated revision to comply with RFC 8791.

       This version is not backward compatible with the version
       published in RFC 8782.";
      reference
        "RFC 9132: Distributed Denial-of-Service Open Threat
        	  Signaling (DOTS) Signal Channel Specification";

    }

    revision "2020-05-28" {
      description "Initial revision.";
      reference
        "RFC 8782: Distributed Denial-of-Service Open Threat
        	  Signaling (DOTS) Signal Channel Specification";

    }

    sx:structure "dots-signal";

    grouping mitigation-scope {
      description
        "Specifies the scope of the mitigation request.";
      list scope {
        description
          "The scope of the request.";
        uses data-channel:target;

        leaf-list alias-name {
          type string;
          description
            "An alias name that points to a resource.";
        }

        leaf lifetime {
          type union {
            type uint32;
            type int32 {
              range "-1";
            }
          }
          units "seconds";
          default "3600";
          description
            "Indicates the lifetime of the mitigation request.

           A lifetime of '0' in a mitigation request is an
           invalid value.

           A lifetime of negative one (-1) indicates indefinite
           lifetime for the mitigation request.

           Lifetime is mandatory in a mitigation request.

           The DOTS server must always indicate the actual lifetime
           in the response to an accepted mitigation request and the
           remaining lifetime in status messages sent to the
           DOTS client.";
        }

        leaf trigger-mitigation {
          type boolean;
          default "true";
          description
            "If set to 'false', DDoS mitigation will not be
           triggered unless the DOTS signal channel
           session is lost.";
        }

        choice direction {
          description
            "Indicates the communication direction in which the
           data nodes can be included.";
          case server-to-client-only {
            description
              "These data nodes appear only in a mitigation message
             sent from the server to the client.";
            leaf mid {
              type uint32;
              description
                "Mitigation request identifier.

               This identifier must be unique for each mitigation
               request bound to the DOTS client.";
            }

            leaf mitigation-start {
              type uint64;
              description
                "Mitigation start time is represented in seconds
               relative to 1970-01-01T00:00:00Z in UTC time.

               This is a mandatory attribute when an attack
               mitigation is active.  It must not be returned for
               a mitigation with 'status' code set to 8.";
            }

            leaf status {
              type iana-dots-signal:status;
              description
                "Indicates the status of a mitigation request.
               It must be included in responses only.

               This is a mandatory attribute if a mitigation
               request is accepted and processed by the server.";
            }

            container conflict-information {
              description
                "Indicates that a conflict is detected.";
              leaf conflict-status {
                type iana-dots-signal:conflict-status;
                description
                  "Indicates the conflict status.";
              }

              leaf conflict-cause {
                type iana-dots-signal:conflict-cause;
                description
                  "Indicates the cause of the conflict.";
              }

              leaf retry-timer {
                type uint32;
                units "seconds";
                description
                  "The DOTS client must not resend the
                 same request that has a conflict before the expiry
                 of this timer.";
              }

              container conflict-scope {
                description
                  "Provides more information about the conflict
                 scope.";
                uses data-channel:target {
                  when
                    "/dots-signal/scope/conflict-information/"
                      + "conflict-cause = 'overlapping-targets'";
                }

                leaf-list alias-name {
                  when
                    "../../conflict-cause = 'overlapping-targets'";
                  type string;
                  description
                    "Conflicting alias-name.";
                }

                list acl-list {
                  when
                    "../../conflict-cause ="
                      + " 'conflict-with-acceptlist'";
                  key "acl-name";
                  description
                    "List of conflicting ACLs, as defined in the DOTS
                   data channel.  These ACLs are uniquely defined by
                   cuid and acl-name.";
                  leaf acl-name {
                    type leafref {
                      path
                        "/data-channel:dots-data"
                          + "/data-channel:dots-client"
                          + "/data-channel:acls"
                          + "/data-channel:acl/data-channel:name";
                    }
                    description
                      "Reference to the conflicting ACL name bound to
                     a DOTS client.";
                  }

                  leaf acl-type {
                    type leafref {
                      path
                        "/data-channel:dots-data"
                          + "/data-channel:dots-client"
                          + "/data-channel:acls"
                          + "/data-channel:acl/data-channel:type";
                    }
                    description
                      "Reference to the conflicting ACL type bound to
                     a DOTS client.";
                  }
                }  // list acl-list

                leaf mid {
                  when
                    "../../conflict-cause = 'overlapping-targets'";
                  type uint32;
                  description
                    "Reference to the conflicting 'mid' bound to
                   the same DOTS client.";
                }
              }  // container conflict-scope
            }  // container conflict-information

            leaf bytes-dropped {
              type yang:zero-based-counter64;
              units "bytes";
              description
                "The total dropped byte count for the mitigation
               request since the attack mitigation was triggered.
               The count wraps around when it reaches the maximum
               value of counter64 for dropped bytes.";
            }

            leaf bps-dropped {
              type yang:gauge64;
              units "bytes per second";
              description
                "The average number of dropped bytes per second for
               the mitigation request since the attack
               mitigation was triggered.  This should be over
               five-minute intervals (that is, measuring bytes
               into five-minute buckets and then averaging these
               buckets over the time since the mitigation was
               triggered).";
            }

            leaf pkts-dropped {
              type yang:zero-based-counter64;
              description
                "The total number of dropped packet count for the
               mitigation request since the attack mitigation was
               triggered.  The count wraps around when it reaches
               the maximum value of counter64 for dropped packets.";
            }

            leaf pps-dropped {
              type yang:gauge64;
              units "packets per second";
              description
                "The average number of dropped packets per second
               for the mitigation request since the attack
               mitigation was triggered.  This should be over
               five-minute intervals (that is, measuring packets
               into five-minute buckets and then averaging these
               buckets over the time since the mitigation was
               triggered).";
            }
          }  // case server-to-client-only

          case client-to-server-only {
            description
              "These data nodes appear only in a mitigation message
             sent from the client to the server.";
            leaf attack-status {
              type iana-dots-signal:attack-status;
              description
                "Indicates the status of an attack as seen by the
               DOTS client.

               This is a mandatory attribute when a client
               performs an efficacy update.";
            }
          }  // case client-to-server-only
        }  // choice direction
      }  // list scope
    }  // grouping mitigation-scope

    grouping config-parameters {
      description
        "Subset of DOTS signal channel session configuration.";
      container heartbeat-interval {
        description
          "DOTS agents regularly send heartbeats to each other
         after mutual authentication is successfully
         completed in order to keep the DOTS signal channel
         open.";
        choice direction {
          description
            "Indicates the communication direction in which the
           data nodes can be included.";
          case server-to-client-only {
            description
              "These data nodes appear only in a mitigation message
             sent from the server to the client.";
            leaf max-value {
              type uint16;
              units "seconds";
              description
                "Maximum acceptable heartbeat-interval value.";
            }

            leaf min-value {
              type uint16;
              units "seconds";
              description
                "Minimum acceptable heartbeat-interval value.";
            }
          }  // case server-to-client-only
        }  // choice direction

        leaf current-value {
          type uint16;
          units "seconds";
          default "30";
          description
            "Current heartbeat-interval value.

           '0' means that heartbeat mechanism is deactivated.";
        }
      }  // container heartbeat-interval

      container missing-hb-allowed {
        description
          "Maximum number of missing heartbeats allowed.";
        choice direction {
          description
            "Indicates the communication direction in which the
           data nodes can be included.";
          case server-to-client-only {
            description
              "These data nodes appear only in a mitigation message
             sent from the server to the client.";
            leaf max-value {
              type uint16;
              description
                "Maximum acceptable missing-hb-allowed value.";
            }

            leaf min-value {
              type uint16;
              description
                "Minimum acceptable missing-hb-allowed value.";
            }
          }  // case server-to-client-only
        }  // choice direction

        leaf current-value {
          type uint16;
          default "15";
          description
            "Current missing-hb-allowed value.";
        }
      }  // container missing-hb-allowed

      container probing-rate {
        description
          "The limit for sending Non-confirmable messages with
         no response.";
        choice direction {
          description
            "Indicates the communication direction in which the
           data nodes can be included.";
          case server-to-client-only {
            description
              "These data nodes appear only in a mitigation message
             sent from the server to the client.";
            leaf max-value {
              type uint16;
              units "byte/second";
              description
                "Maximum acceptable probing-rate value.";
            }

            leaf min-value {
              type uint16;
              units "byte/second";
              description
                "Minimum acceptable probing-rate value.";
            }
          }  // case server-to-client-only
        }  // choice direction

        leaf current-value {
          type uint16;
          units "byte/second";
          default "5";
          description
            "Current probing-rate value.";
        }
      }  // container probing-rate

      container max-retransmit {
        description
          "Maximum number of retransmissions of a Confirmable
         message.";
        choice direction {
          description
            "Indicates the communication direction in which the
           data nodes can be included.";
          case server-to-client-only {
            description
              "These data nodes appear only in a mitigation message
             sent from the server to the client.";
            leaf max-value {
              type uint16;
              description
                "Maximum acceptable max-retransmit value.";
            }

            leaf min-value {
              type uint16;
              description
                "Minimum acceptable max-retransmit value.";
            }
          }  // case server-to-client-only
        }  // choice direction

        leaf current-value {
          type uint16;
          default "3";
          description
            "Current max-retransmit value.";
        }
      }  // container max-retransmit

      container ack-timeout {
        description
          "Initial retransmission timeout value.";
        choice direction {
          description
            "Indicates the communication direction in which the
           data nodes can be included.";
          case server-to-client-only {
            description
              "These data nodes appear only in a mitigation message
             sent from the server to the client.";
            leaf max-value-decimal {
              type decimal64 {
                fraction-digits 2;
              }
              units "seconds";
              description
                "Maximum ack-timeout value.";
            }

            leaf min-value-decimal {
              type decimal64 {
                fraction-digits 2;
              }
              units "seconds";
              description
                "Minimum ack-timeout value.";
            }
          }  // case server-to-client-only
        }  // choice direction

        leaf current-value-decimal {
          type decimal64 {
            fraction-digits 2;
          }
          units "seconds";
          default "2";
          description
            "Current ack-timeout value.";
        }
      }  // container ack-timeout

      container ack-random-factor {
        description
          "Random factor used to influence the timing of
         retransmissions.";
        choice direction {
          description
            "Indicates the communication direction in which the
           data nodes can be included.";
          case server-to-client-only {
            description
              "These data nodes appear only in a mitigation message
             sent from the server to the client.";
            leaf max-value-decimal {
              type decimal64 {
                fraction-digits 2;
              }
              description
                "Maximum acceptable ack-random-factor value.";
            }

            leaf min-value-decimal {
              type decimal64 {
                fraction-digits 2;
              }
              description
                "Minimum acceptable ack-random-factor value.";
            }
          }  // case server-to-client-only
        }  // choice direction

        leaf current-value-decimal {
          type decimal64 {
            fraction-digits 2;
          }
          default "1.5";
          description
            "Current ack-random-factor value.";
        }
      }  // container ack-random-factor
    }  // grouping config-parameters

    grouping signal-config {
      description
        "DOTS signal channel session configuration.";
      container mitigating-config {
        description
          "Configuration parameters to use when a mitigation
         is active.";
        uses config-parameters;
      }  // container mitigating-config

      container idle-config {
        description
          "Configuration parameters to use when no mitigation
         is active.";
        uses config-parameters;
      }  // container idle-config
    }  // grouping signal-config

    grouping redirected-signal {
      description
        "Grouping for the redirected signaling.";
      choice direction {
        description
          "Indicates the communication direction in which the
         data nodes can be included.";
        case server-to-client-only {
          description
            "These data nodes appear only in a mitigation message
           sent from the server to the client.";
          leaf alt-server {
            type inet:domain-name;
            mandatory true;
            description
              "FQDN of an alternate server.";
          }

          leaf-list alt-server-record {
            type inet:ip-address;
            description
              "List of records for the alternate server.";
          }
        }  // case server-to-client-only
      }  // choice direction
    }  // grouping redirected-signal

    container dots-signal {
      description
        "Main structure for DOTS signal message.

       A DOTS signal message can be a mitigation, a configuration,
       a redirected, or a heartbeat signal message.";
      choice message-type {
        description
          "Can be a mitigation, a configuration, a redirect, or
         a heartbeat message.";
        case mitigation-scope {
          description
            "Mitigation scope of a mitigation message.";
          uses mitigation-scope;
        }  // case mitigation-scope

        case signal-config {
          description
            "Configuration message.";
          uses signal-config;
        }  // case signal-config

        case redirected-signal {
          description
            "Redirected signaling.";
          uses redirected-signal;
        }  // case redirected-signal

        case heartbeat {
          description "DOTS heartbeats.";
          leaf peer-hb-status {
            type boolean;
            mandatory true;
            description
              "Indicates whether a DOTS agent receives heartbeats
             from its peer.  The value is set to 'true' if the
             DOTS agent is receiving heartbeat messages
             from its peer.";
          }
        }  // case heartbeat
      }  // choice message-type
    }  // container dots-signal
  }  // module ietf-dots-signal-channel