NETCONF Working Group K. Watsen
Internet-Draft Watsen Networks
Intended status: Standards Track November 20, 2019
Expires: May 23, 2020

YANG Groupings for HTTP Clients and HTTP Servers
draft-ietf-netconf-http-client-server-01

Abstract

This document defines two YANG modules: the first defines a minimal grouping for configuring an HTTP client, and the second defines a minimal grouping for configuring an HTTP server. It is intended that these groupings will be used to help define the configuration for simple HTTP-based protocols (not for complete webservers or browsers).

Editorial Note (To be removed by RFC Editor)

This draft contains many placeholder values that need to be replaced with finalized values at the time of publication. This note summarizes all of the substitutions that are needed. No other RFC Editor instructions are specified elsewhere in this document.

Artwork in this document contains placeholder values for the date of publication of this draft. Please apply the following replacement:

The following Appendix section is to be removed prior to publication:

Status of This Memo

This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.

Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet-Drafts is at https://datatracker.ietf.org/drafts/current/.

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This Internet-Draft will expire on May 23, 2020.

Copyright Notice

Copyright (c) 2019 IETF Trust and the persons identified as the document authors. All rights reserved.

This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License.


Table of Contents

1. Introduction

This document defines two YANG 1.1 [RFC7950] modules: the first defines a minimal grouping for configuring an HTTP client, and the second defines a minimal grouping for configuring an HTTP server. It is intended that these groupings will be used to help define the configuration for simple HTTP-based protocols (not for complete webservers or browsers).

2. Terminology

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.

3. The HTTP Client Model

3.1. Tree Diagram

This section provides a tree diagram [RFC8340] for the "ietf-http-client" module.

module: ietf-http-client

  grouping client-identity-grouping
    +-- (auth-type)
       +--:(basic)
          +-- basic {basic-auth}?
             +-- user-id     string
             +-- password    string
  grouping http-client-grouping
    +-- client-identity
    |  +---u client-identity-grouping
    +-- proxy-server! {proxy-connect}?
       +-- tcp-client-parameters
       |  +---u tcpc:tcp-client-grouping
       +-- tls-client-parameters
       |  +---u tlsc:tls-client-grouping
       +-- proxy-client-identity
          +---u client-identity-grouping

3.2. Example Usage

This section presents an example showing the http-client-grouping populated with some data.

<http-client xmlns="urn:ietf:params:xml:ns:yang:ietf-http-client">
  <client-identity>
    <basic>
      <user-id>bob</user-id>
      <password>secret</password>
    </basic>
  </client-identity>
</http-client>

3.3. YANG Module

This YANG module has normative references to [RFC6991].

<CODE BEGINS> file "ietf-http-client@2019-11-20.yang"

module ietf-http-client {
  yang-version 1.1;
  namespace "urn:ietf:params:xml:ns:yang:ietf-http-client";
  prefix httpc;

  import ietf-tcp-client {
    prefix tcpc;
    reference
      "RFC AAAA: YANG Groupings for TCP Clients and TCP Servers";
  }
 
  import ietf-tls-client {
    prefix tlsc;
    reference
      "RFC BBBB: YANG Groupings for TLS Clients and TLS Servers";
  }

  import ietf-netconf-acm {
    prefix nacm;
    reference
      "RFC 8341: Network Configuration Access Control Model";
  }

  organization
    "IETF NETCONF (Network Configuration) Working Group";

  contact
    "WG Web:   <http://datatracker.ietf.org/wg/netconf/>
     WG List:  <mailto:netconf@ietf.org>
     Author:   Kent Watsen <mailto:kent+ietf@watsen.net>";

  description
    "This module defines reusable groupings for HTTP clients that
     can be used as a basis for specific HTTP client instances.

     Copyright (c) 2019 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
     (https://trustee.ietf.org/license-info).

     This version of this YANG module is part of RFC XXXX
     (https://www.rfc-editor.org/info/rfcXXXX); see the RFC
     itself for full legal notices.

     The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL',
     'SHALL NOT', 'SHOULD', 'SHOULD NOT', 'RECOMMENDED',
     'NOT RECOMMENDED', 'MAY', and 'OPTIONAL' in this document
     are to be interpreted as described in BCP 14 (RFC 2119)
     (RFC 8174) when, and only when, they appear in all
     capitals, as shown here.";

  revision 2019-11-20 {
    description
      "Initial version";
    reference
      "RFC XXXX: YANG Groupings for HTTP Clients and HTTP Servers";
  }

  // Features

  feature proxy-connect {
    description
      "Proxy connection configuration is configurable for
       HTTP clients on the server implementing this feature.";
  }

  feature basic-auth {
    description
      "The 'basic-auth' feature indicates that the client
       may be configured to use the 'basic' HTTP authentication
       scheme.";
    reference
      "RFC 7617: The 'Basic' HTTP Authentication Scheme";
  }

  // Groupings

  grouping client-identity-grouping {
    description
      "The credentials used by the client to authenticate to
       the HTTP server.";
    choice auth-type {
      nacm:default-deny-write;
      mandatory true;
      description
        "The authentication type.";
      case basic {
        container basic {
          if-feature "basic-auth";
          leaf user-id {
            type string;
            mandatory true;
            description
              "The user-id for the authenticating client.";
          }
          leaf password {
            nacm:default-deny-all;
            type string;
            mandatory true;
            description
              "The password for the authenticating client.";
          }
          description
            "The 'basic' HTTP scheme credentials.";
          reference
            "RFC 7617: The 'Basic' HTTP Authentication Scheme";
        }
      }
    }
  } // grouping client-identity-grouping

  grouping http-client-grouping {
    description
      "A reusable grouping for configuring a HTTP client,
       including the IP address and port number it initiates
       a connections to.
       
       Note that this grouping uses fairly typical descendent
       node names such that a stack of 'uses' statements will
       have name conflicts.  It is intended that the consuming
       data model will resolve the issue (e.g., by wrapping
       the 'uses' statement in a container called 
       'http-client-parameters').  This model purposely does
       not do this itself so as to provide maximum flexibility
       to consuming models.";

    container client-identity {
      description
        "The identity the HTTP client should use when
         authenticating itself to the HTTP server.";
      uses client-identity-grouping;
    }

    container proxy-server {
      nacm:default-deny-write;
      if-feature "proxy-connect";
      presence true; // only so ex-http-client can pass validation?
      container tcp-client-parameters {
        description
          "A wrapper around the TCP parameters to avoid
           name collisions.";
        uses "tcpc:tcp-client-grouping";
      }
      container tls-client-parameters {
        description
          "A wrapper around the TLS parameters to avoid
           name collisions.";
        uses "tlsc:tls-client-grouping";
      }
      container proxy-client-identity {
        description
          "The identity the HTTP client should use when
           authenticating itself to the HTTP server.";
        uses client-identity-grouping;
      }
      description
        "Proxy server settings.";
    }
  } // grouping http-client-grouping

} // module ietf-http-client

<CODE ENDS>

4. The HTTP Server Model

4.1. Tree Diagram

This section provides a tree diagram [RFC8340] for the "ietf-http-server" module.

module: ietf-http-server

  grouping http-server-grouping
    +-- server-name?             string
    +-- protocol-versions
    |  +-- protocol-version*   enumeration
    +-- client-authentication! {client-auth-config-supported}?
       +-- users
          +-- user* [user-id]
             +-- user-id?       string
             +-- (auth-type)?
                +--:(basic)
                   +-- basic {basic-auth}?
                      +-- user-id?    string
                      +-- password?   ianach:crypt-hash

4.2. Example Usage

This section presents an example showing the http-server-grouping populated with some data.

<http-server xmlns="urn:ietf:params:xml:ns:yang:ietf-http-server">
  <server-name>foo.example.com</server-name>
  <protocol-versions>
    <protocol-version>HTTP/1.1</protocol-version>
    <protocol-version>HTTP/2.0</protocol-version>
  </protocol-versions>
</http-server>

4.3. YANG Module

This YANG module has normative references to [RFC6991].

<CODE BEGINS> file "ietf-http-server@2019-11-20.yang"

module ietf-http-server {
  yang-version 1.1;
  namespace "urn:ietf:params:xml:ns:yang:ietf-http-server";
  prefix https;

  import iana-crypt-hash {
    prefix ianach;
    reference
      "RFC 7317: A YANG Data Model for System Management";
  }

  import ietf-netconf-acm {
    prefix nacm;
    reference
      "RFC 8341: Network Configuration Access Control Model";
  }

  organization
    "IETF NETCONF (Network Configuration) Working Group";

  contact
    "WG Web:   <http://datatracker.ietf.org/wg/netconf/>
     WG List:  <mailto:netconf@ietf.org>
     Author:   Kent Watsen <mailto:kent+ietf@watsen.net>";

  description
    "This module defines reusable groupings for HTTP servers that
     can be used as a basis for specific HTTP server instances.

     Copyright (c) 2019 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
     (https://trustee.ietf.org/license-info).

     This version of this YANG module is part of RFC XXXX
     (https://www.rfc-editor.org/info/rfcXXXX); see the RFC
     itself for full legal notices.

     The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL',
     'SHALL NOT', 'SHOULD', 'SHOULD NOT', 'RECOMMENDED',
     'NOT RECOMMENDED', 'MAY', and 'OPTIONAL' in this document
     are to be interpreted as described in BCP 14 (RFC 2119)
     (RFC 8174) when, and only when, they appear in all
     capitals, as shown here.";

  revision 2019-11-20 {
    description
      "Initial version";
    reference
      "RFC XXXX: YANG Groupings for HTTP Clients and HTTP Servers";
  }

  // Features

  feature client-auth-config-supported {
    description
      "Indicates that the configuration for how to authenticate
       clients can be configured herein, as opposed to in an
       application specific location.  That is, to support the
       consuming data models that prefer to place client
       authentication with client definitions, rather then
       in a data model principally concerned with configuring
       the transport.";
  }

  feature external-client-auth-supported {
    description
      "Indicates that the HTTP server supports external configuration
       of client credentials.";
  }

  feature basic-auth {
    description
      "The 'basic-auth' feature indicates that the server
       may be configured authenticate users using the 'basic'
       HTTP authentication scheme.";
    reference
      "RFC 7617: The 'Basic' HTTP Authentication Scheme";
  }


  // Groupings

  grouping http-server-grouping {
    description
      "A reusable grouping for configuring an HTTP server.
       
       Note that this grouping uses fairly typical descendent
       node names such that a stack of 'uses' statements will
       have name conflicts.  It is intended that the consuming
       data model will resolve the issue (e.g., by wrapping
       the 'uses' statement in a container called 
       'http-server-parameters').  This model purposely does
       not do this itself so as to provide maximum flexibility
       to consuming models.";

    leaf server-name {
      nacm:default-deny-write;
      type string;
      description
        "The value of the 'Server' header field.  If not set, then
         underlying software's default value is used.  Set to the
         empty string to disable.";
    } 

    container protocol-versions {
      nacm:default-deny-write;
      description
        "A list of HTTP protocol versions supported by this
         server.";
      leaf-list protocol-version {
        type enumeration {
          enum "HTTP/1.0" {
            description
              "The server supports the 'HTTP/1.0' protocol.";
          }
          enum "HTTP/1.1" {
            description
              "The server supports the 'HTTP/1.1' protocol.";
          }
          enum "HTTP/2.0" {
            description
              "The server supports the 'HTTP/2.0' protocol.";
          }
        }
        description
          "An HTTP protocol version supported by this server.";
      }
    }

    container client-authentication {
      if-feature "client-auth-config-supported";
      nacm:default-deny-write;
      presence
        "Indicates that HTTP based client authentication is
         supported (i.e., the server will request that the
         HTTP client send authenticate when needed).  This
         is needed as some HTTP-based protocols may only
         support, e.g., TLS-level client authentication.";
      description
        "Specifies how the HTTP server can authenticate HTTP
         clients.";
      container users {
        description
          "A list of locally configured users.";
        list user {
          key user-id;
          description
            "The list of local users configured on this device.";
          leaf user-id {
            type string;
            description
              "The user-id for the authenticating client.";
          }
          choice auth-type {
            description
              "The authentication type.";
            container basic {
              if-feature "basic-auth";
              leaf user-id {
                type string;
                description
                  "The user-id for the authenticating client.";
              }
              leaf password {
                nacm:default-deny-write;
                type ianach:crypt-hash;
                description
                  "The password for the authenticating client.";
              }
              description
                "The 'basic' HTTP scheme credentials.";
              reference
                "RFC 7617:
                  The 'Basic' HTTP Authentication Scheme";
            }
          }
        }
      }
    } // container client-authentication
  } // grouping http-server-grouping
}

<CODE ENDS>

5. Security Considerations

The YANG modules defined in this document are designed to be accessed via YANG based management protocols, such as NETCONF [RFC6241] and RESTCONF [RFC8040]. Both of these protocols have mandatory-to-implement secure transport layers (e.g., SSH, HTTP) with mutual authentication.

The NETCONF access control model (NACM) [RFC8341] provides the means to restrict access for particular users to a pre-configured subset of all available protocol operations and content.

Since the modules defined in this document only define groupings, these considerations are primarily for the designers of other modules that use these groupings.

There are a number of data nodes defined in the YANG modules that are writable/creatable/deletable (i.e., config true, which is the default). These data nodes may be considered sensitive or vulnerable in some network environments. Write operations (e.g., edit-config) to these data nodes without proper protection can have a negative effect on network operations. These are the subtrees and data nodes and their sensitivity/vulnerability:

FIXME: (pending - TBD)

Some of the readable data nodes in the YANG modules may be considered sensitive or vulnerable in some network environments. It is thus important to control read access (e.g., via get, get-config, or notification) to these data nodes. These are the subtrees and data nodes and their sensitivity/vulnerability:

FIXME: (pending client auth params?)

Some of the RPC operations in this YANG module may be considered sensitive or vulnerable in some network environments. It is thus important to control access to these operations. These are the operations and their sensitivity/vulnerability:

The modules defined in this document do not define any 'RPC' or 'action' statements.

6. IANA Considerations

6.1. The IETF XML Registry

This document registers two URIs in the "ns" subregistry of the IETF XML Registry [RFC3688]. Following the format in [RFC3688], the following registrations are requested:

   URI: urn:ietf:params:xml:ns:yang:ietf-http-client
   Registrant Contact: The NETCONF WG of the IETF.
   XML: N/A, the requested URI is an XML namespace.

   URI: urn:ietf:params:xml:ns:yang:ietf-http-server
   Registrant Contact: The NETCONF WG of the IETF.
   XML: N/A, the requested URI is an XML namespace.

6.2. The YANG Module Names Registry

This document registers two YANG modules in the YANG Module Names registry [RFC6020]. Following the format in [RFC6020], the following registrations are requested:

   name:         ietf-http-client
   namespace:    urn:ietf:params:xml:ns:yang:ietf-http-client
   prefix:       httpc
   reference:    RFC XXXX

   name:         ietf-http-server
   namespace:    urn:ietf:params:xml:ns:yang:ietf-http-server
   prefix:       https
   reference:    RFC XXXX

7. References

7.1. Normative References

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997.
[RFC6020] Bjorklund, M., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, DOI 10.17487/RFC6020, October 2010.
[RFC6991] Schoenwaelder, J., "Common YANG Data Types", RFC 6991, DOI 10.17487/RFC6991, July 2013.
[RFC7950] Bjorklund, M., "The YANG 1.1 Data Modeling Language", RFC 7950, DOI 10.17487/RFC7950, August 2016.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017.
[RFC8341] Bierman, A. and M. Bjorklund, "Network Configuration Access Control Model", STD 91, RFC 8341, DOI 10.17487/RFC8341, March 2018.

7.2. Informative References

[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, DOI 10.17487/RFC3688, January 2004.
[RFC6241] Enns, R., Bjorklund, M., Schoenwaelder, J. and A. Bierman, "Network Configuration Protocol (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011.
[RFC8040] Bierman, A., Bjorklund, M. and K. Watsen, "RESTCONF Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017.
[RFC8340] Bjorklund, M. and L. Berger, "YANG Tree Diagrams", BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018.

Appendix A. Change Log

A.1. 00 to 01

Acknowledgements

The authors would like to thank for following for lively discussions on list and in the halls (ordered by last name): TBD

Author's Address

Kent Watsen Watsen Networks EMail: kent+ietf@watsen.net