module ietf-syslog {

    yang-version 1;

    namespace
      "urn:ietf:params:xml:ns:yang:ietf-syslog";

    prefix syslog;

    import ietf-inet-types {
      prefix inet;
    }
    import ietf-interfaces {
      prefix if;
    }
    import ietf-syslog-types {
      prefix syslogtypes;
    }

    organization
      "IETF NETMOD (NETCONF Data Modeling Language) 
     Working Group";

    contact
      "WG Web:   <http://tools.ietf.org/wg/netmod/>
     WG List:  <mailto:netmod@ietf.org>
     
     WG Chair: Lou Berger
               <mailto:lberger@labn.net>
     
     WG Chair: Kent Watsen
               <mailto:kwatsen@juniper.net>
     
     Editor:   Kiran Agrahara Sreenivasa
               <mailto:kkoushik@cisco.com>
     
     Editor:   Clyde Wildes
               <mailto:cwildes@cisco.com>";

    description
      "This module contains a collection of YANG definitions 
     for syslog configuration.
     
     Copyright (c) 2016 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).
     
     The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL', 'SHALL
     NOT', 'SHOULD', 'SHOULD NOT', 'RECOMMENDED', 'MAY', and
     'OPTIONAL' in the module text are to be interpreted as described
     in RFC 2119 (http://tools.ietf.org/html/rfc2119).
     
     This version of this YANG module is part of RFC XXXX
     (http://tools.ietf.org/html/rfcXXXX); see the RFC itself for
     full legal notices.";

    reference
      "RFC 5424: The Syslog Protocol
       RFC 5425: Transport Layer Security (TLS) Transport Mapping for Syslog
       RFC 5426: Transmission of Syslog Messages over UDP
       RFC 6587: Transmission of Syslog Messages over TCP
       RFC 5848: Signed Syslog Messages";


    revision "2016-07-08" {
      description "Initial Revision";
      reference
        "RFC XXXX: Syslog YANG Model";

    }


    feature buffer-limit-bytes {
      description
        "This feature indicates that local memory logging buffers
       are limited in size using a limit expressed in bytes.";
    }

    feature buffer-limit-messages {
      description
        "This feature indicates that local memory logging buffers
       are limited in size using a limit expressed in number
       of log messages.";
    }

    feature file-limit-size {
      description
        "This feature indicates that file logging resources
       are managed using size and number limits.";
    }

    feature file-limit-duration {
      description
        "This feature indicates that file logging resources
       are managed using time based limits.";
    }

    feature select-sev-compare {
      description
        "This feature represents the ability to select messages 
       using the additional operators equal to, or not equal to 
       when comparing the syslog message severity.";
    }

    feature select-match {
      description
        "This feature represents the ability to select messages based
       on a Posix 1003.2 regular expression pattern match.";
    }

    feature structured-data {
      description
        "This feature represents the ability to log messages 
       in structured-data format as per RFC 5424.";
    }

    feature signed-messages {
      description
        "This feature represents the ability to configure signed 
       syslog messages according to RFC 5848.";
    }

    grouping log-severity {
      description
        "This grouping defines the severity value that is used to 
       select log messages.";
      leaf severity {
        type union {
          type syslogtypes:severity;
          type enumeration {
            enum "all" {
              value -1;
              description
                "This enum describes the case where all severities 
               are selected.";
            }
            enum "none" {
              value -2;
              description
                "This enum describes the case where no severities 
               are selected.";
            }
          }
        }
        mandatory true;
        description
          "This leaf specifies the syslog message severity. When 
         severity is specified, the default severity comparison 
         is all messages of the specified severity and greater are 
         selected. 'all' is a special case which means all severities
         are selected. 'none' is a special case which means that
         no selection should occur or disable this filter.";
      }

      leaf compare-op {
        when
          "../severity != \"all\" and
                    ../severity != \"none\"" {
          description
            "The compare-op is not applicable for severity 'all' or 
           severity 'none'";
        }
        if-feature select-sev-compare;
        type enumeration {
          enum "equals-or-higher" {
            value 0;
            description
              "This enum specifies all messages of the specified 
             severity and higher are logged according to the 
             given log-action";
          }
          enum "equals" {
            value 1;
            description
              "This enum specifies all messages that are for 
             the specified severity are logged according to the 
             given log-action";
          }
          enum "not-equals" {
            value 2;
            description
              "This enum specifies all messages that are not for 
             the specified severity are logged according to the 
             given log-action";
          }
        }
        default "equals-or-higher";
        description
          "This leaf describes the option to specify how the 
         severity comparison is performed.";
      }
    }  // grouping log-severity

    grouping selector {
      description
        "This grouping defines a syslog selector which is used to 
       select log messages for the log-action (buffer, file, 
       etc). Choose one of the following:
         no-log-facility
         log-facility [<facility> <severity>...]";
      container log-selector {
        description
          "This container describes the log selector parameters 
         for syslog.";
        choice selector-facility {
          mandatory true;
          description
            "This choice describes the option to specify no 
           facilities, or a specific facility which can be
           all for all facilities.";
          case no-log-facility {
            description
              "This case specifies no facilities will match when 
             comparing the syslog message facility. This is a 
             method that can be used to effectively disable a 
             particular log-action (buffer, file, etc).";
            leaf no-facilities {
              type empty;
              description
                "This leaf specifies that no facilities are selected 
               for this log-action.";
            }
          }  // case no-log-facility

          case log-facility {
            description
              "This case specifies one or more specified facilities 
             will match when comparing the syslog message facility.";
            list log-facility {
              key "facility";
              description
                "This list describes a collection of syslog 
               facilities and severities.";
              leaf facility {
                type union {
                  type identityref {
                    base syslogtypes:syslog-facility;
                  }
                  type enumeration {
                    enum "all" {
                      value 0;
                      description
                        "This enum describes the case where all 
                       facilities are requested.";
                    }
                  }
                }
                description
                  "The leaf uniquely identifies a syslog facility.";
              }

              uses log-severity;
            }  // list log-facility
          }  // case log-facility
        }  // choice selector-facility

        leaf pattern-match {
          if-feature select-match;
          type string;
          description
            "This leaf desribes a Posix 1003.2 regular expression 
           string that can be used to select a syslog message for 
           logging. The match is performed on the RFC 5424 
           SYSLOG-MSG field.";
        }
      }  // container log-selector
    }  // grouping selector

    grouping structured-data {
      description
        "This grouping defines the syslog structured data option 
       which is used to select the format used to write log 
       messages.";
      leaf structured-data {
        if-feature structured-data;
        type boolean;
        default "false";
        description
          "This leaf describes how log messages are written to 
         the log file. If true, messages will be written 
         with one or more STRUCTURED-DATA elements as per 
         RFC5424; if false, messages will be written with 
         STRUCTURED-DATA = NILVALUE.";
      }
    }  // grouping structured-data

    container syslog {
      description
        "This container describes the configuration parameters for 
       syslog.";
      container actions {
        description
          "This container describes the log-action parameters 
         for syslog.";
        container console {
          presence
            "Enables logging console configuration";
          description
            "This container describes the configuration parameters for 
           console logging.";
          uses selector;
        }  // container console

        container buffer {
          description
            "This container describes the configuration parameters for 
           local memory buffer logging. The buffer is circular in 
           nature, so newer messages overwrite older messages after 
           the buffer is filled. The method used to read syslog messages
           from the buffer is supplied by the local implementation.";
          uses selector;

          leaf buffer-limit-bytes {
            if-feature buffer-limit-bytes;
            type uint64;
            units "bytes";
            description
              "This leaf configures the amount of memory (in bytes) that 
             will be dedicated to the local memory logging buffer. 
             The default value varies by implementation.";
          }

          leaf buffer-limit-messages {
            if-feature buffer-limit-messages;
            type uint64;
            units "log messages";
            description
              "This leaf configures the number of log messages that 
             will be dedicated to the local memory logging buffer. 
             The default value varies by implementation.";
          }

          uses structured-data;
        }  // container buffer

        container file {
          description
            "This container describes the configuration parameters for 
           file logging. If file-archive limits are not supplied, it
           is assumed that the local implementation defined limits will 
           be used.";
          list log-file {
            key "name";
            description
              "This list describes a collection of local logging 
             files.";
            leaf name {
              type inet:uri {
                pattern "file:.*";
              }
              description
                "This leaf specifies the name of the log file which 
               MUST use the uri scheme file:.";
            }

            uses selector;

            uses structured-data;

            container file-archive {
              description
                "This container describes the configuration 
               parameters for log file archiving.";
              leaf number-of-files {
                if-feature file-limit-size;
                type uint32;
                description
                  "This leaf specifies the maximum number of log 
                 files retained. Specify 1 for implementations 
                 that only support one log file.";
              }

              leaf max-file-size {
                if-feature file-limit-size;
                type uint64;
                units "megabytes";
                description
                  "This leaf specifies the maximum log file size.";
              }

              leaf rollover {
                if-feature file-limit-duration;
                type uint32;
                units "minutes";
                description
                  "This leaf specifies the length of time that log 
                 events should be written to a specific log file. 
                 Log events that arrive after the rollover period 
                 cause the current log file to be closed and a new 
                 log file to be opened.";
              }

              leaf retention {
                if-feature file-limit-duration;
                type uint16;
                units "hours";
                description
                  "This leaf specifies the length of time that 
                 completed/closed log event files should be stored 
                 in the file system before they are deleted.";
              }
            }  // container file-archive
          }  // list log-file
        }  // container file

        container remote {
          description
            "This container describes the configuration parameters for 
           forwarding syslog messages to remote relays or collectors.";
          list destination {
            key "name";
            description
              "This list describes a collection of remote logging 
             destinations.";
            leaf name {
              type string;
              description
                "An arbitrary name for the endpoint to connect to.";
            }

            choice transport {
              mandatory true;
              description
                "This choice describes the transport option.";
              container tcp {
                description
                  "This container describes the TCP transport
                   options.";
                reference
                  "RFC 6587: Transmission of Syslog Messages over TCP";

                leaf address {
                  type inet:host;
                  description
                    "The leaf uniquely specifies the address of 
                     the remote host. One of the following must 
                     be specified: an ipv4 address, an ipv6 
                     address, or a host name.";
                }

                leaf port {
                  type inet:port-number;
                  default "514";
                  description
                    "This leaf specifies the port number used to 
                     deliver messages to the remote server.";
                }
              }  // container tcp
              container udp {
                description
                  "This container describes the UDP transport
                   options.";
                reference
                  "RFC 5426: Transmission of Syslog Messages over UDP";

                leaf address {
                  type inet:host;
                  description
                    "The leaf uniquely specifies the address of 
                     the remote host. One of the following must be 
                     specified: an ipv4 address, an ipv6 address, 
                     or a host name.";
                }

                leaf port {
                  type inet:port-number;
                  default "514";
                  description
                    "This leaf specifies the port number used to 
                     deliver messages to the remote server.";
                }
              }  // container udp
              container tls {
                description
                  "This container describes the TLS transport options.";
                reference
                  "RFC 5425: Transport Layer Security (TLS) Transport
                  Mapping for Syslog ";

              }  // container tls
            }  // choice transport

            uses selector;

            leaf destination-facility {
              type identityref {
                base syslogtypes:syslog-facility;
              }
              default "syslogtypes:local7";
              description
                "This leaf specifies the facility used in messages 
               delivered to the remote server.";
            }

            leaf source-interface {
              type if:interface-ref;
              description
                "This leaf sets the source interface for the remote 
               syslog server. Either the interface name or the 
               interface IP address can be specified. If not set, 
               messages sent to a remote syslog server will 
               contain the IP address of the interface the syslog 
               message uses to exit the network element";
            }

            uses structured-data;

            container syslog-sign {
              if-feature signed-messages;
              presence
                "If present, syslog-sign is activated.";
              description
                "This container describes the configuration 
               parameters for signed syslog messages as described 
               by RFC 5848.";
              reference
                "RFC 5848: Signed Syslog Messages";

              leaf cert-initial-repeat {
                type uint16;
                mandatory true;
                description
                  "This leaf specifies the number of times each 
                 Certificate Block should be sent before the first 
                 message is sent.";
              }

              leaf cert-resend-delay {
                type uint16;
                mandatory true;
                description
                  "This leaf specifies the maximum time delay in 
                 seconds until resending the Certificate Block.";
              }

              leaf cert-resend-count {
                type uint16;
                mandatory true;
                description
                  "This leaf specifies the maximum number of other 
                 syslog messages to send until resending the 
                 Certificate Block.";
              }

              leaf sig-max-delay {
                type uint16;
                mandatory true;
                description
                  "This leaf specifies when to generate a new 
                 Signature Block. If this many seconds have 
                 elapsed since the message with the first message 
                 number of the Signature Block was sent, a new 
                 Signature Block should be generated.";
              }

              leaf sig-number-resends {
                type uint16;
                mandatory true;
                description
                  "This leaf specifies the number of times a 
                 Signature Block is resent. (It is recommended to 
                 select a value of greater than 0 in particular 
                 when the UDP transport [RFC5426] is used.).";
              }

              leaf sig-resend-delay {
                type uint16;
                mandatory true;
                description
                  "This leaf specifies when to send the next 
                 Signature Block transmission based on time. If 
                 this many seconds have elapsed since the previous 
                 sending of this Signature Block, resend it.";
              }

              leaf sig-resend-count {
                type uint16;
                mandatory true;
                description
                  "This leaf specifies when to send the next 
                 Signature Block transmission based on a count. 
                 If this many other syslog messages have been sent 
                 since the previous sending of this Signature 
                 Block, resend it.";
              }
            }  // container syslog-sign
          }  // list destination
        }  // container remote

        container session {
          description
            "This container describes the configuration parameters for
           user CLI session logging configuration.";
          container all-users {
            presence
              "Enables logging to all user sessions.";
            description
              "This container describes the configuration
             parameters for all users.";
            uses selector;
          }  // container all-users

          list user {
            key "name";
            description
              "This list describes a collection of user names.";
            leaf name {
              type string;
              description
                "This leaf uniquely describes a user name which
               is the login name of the user whose session
               is to receive log messages.";
            }

            uses selector;
          }  // list user
        }  // container session
      }  // container actions
    }  // container syslog
  }  // module ietf-syslog