Clixon 5.7.0

17 May 2022

The Clixon 5.7 release introduces (long overdue) NETCONF chunked framing as defined
in RFC 6242. It also introduces a limited http data service and lots of bugfixes.

New features

• Implementation of "chunked framing" according to RFC6242 for Netconf 1.1.
  • First hello is 1.0 EOM framing, then successing rpc is chunked framing
  • See
    • Netconf framing, and
    • Clixon does not switch to chunked framing after NETCONF 1.1 is negotiated
• Extended the Restconf implementation with a limited http-data static service
  • Added two new config options to clixon-config.yang:
    • CLICON_HTTP_DATA_PATH
    • CLICON_HTTP_DATA_ROOT
  • Added feature http-data to restconf-config.yang and the following option that needs to be true
    • enable-http-data
  • Added HTTP_DATA_INTERNAL_REDIRECT compile-time option for internal redirects to index.html
  • For more info, see user manual documentation

API changes on existing protocol/config features

Users may have to change how they access the system

• CLI

  • clixon_cli reconnects to backend if backend restarts with a warning
    • Note that edits to the candidate database or locks will be lost
    • To force the CLI to exit if backend restarts, undef PROTO_RESTART_RECONNECT
    • This is an effect of the fix of Broken pipe error seen in client (cli) when backend restarts and CLICON_SOCK is recreated, the CLI behavior on backend restart is changed.
  • Expansion of YANG leafref type default behavior has changed
    • In the autocli and handcrafted CLI:s using expand_dbvar() the CLI expansion followed the leafrefs to the sources, ie the origin of the leafrefs
    • Instead leafref expansion now expands according to existing leafrefs by default
    • Example:
      • Assume leafref with leafref pointing to source if values:
        • <if>a</if><if>b</if><if>c</if> <ifref>b</ifref>
      • Existing behavior: expand to: a, b, c
      • New default behavior: expand to: b
    • To keep existing behavior, set <CLICON_CLI_EXPAND_LEAFREF>true<CLICON_CLI_EXPAND_LEAFREF>

• Restconf

  • Added 404 return without body if neither restconf, data or streams prefix match

• Netconf:

  • Usage of chunked framing
    • To keep existing end-of-message encoding, set CLICON_NETCONF_BASE_CAPABILITY to 0
    • Added clixon_netconf command-line option -0 and changed -H to -1
      • -0 means dont send hello, but fix netconf base version to 0 and use EOM framing
      • -1 means dont send hello, but fix netconf base version to 1 and use chunked framing
  • Error message data-not-unique changed to return schema nodes instead of XML for RFC7950 compliance

• YANG

  • Instead of removing YANG which is disabled by if-feature, replace it with an yang anydata node.
    • See Adding feature to top level container doesn't work
    • This means XML specified by such YANG is ignored, and it is not an error to access it
    • Note the similarity with CLICON_YANG_UNKNOWN_ANYDATA
  • New clixon-config@2022-03-21.yang revision
    • Added option:
      • CLICON_RESTCONF_API_ROOT
      • CLICON_NETCONF_BASE_CAPABILITY
      • CLICON_HTTP_DATA_PATH
      • CLICON_HTTP_DATA_ROOT
      • CLICON_CLI_EXPAND_LEAFREF
  • New clixon-restconf@2022-03-21.yang revision
    • Added option:
      • enable-http-data
    • Added feature:
      • http-data

C/CLI-API changes on existing features

Developers may need to change their code

• Added nsc parameter to xml2xpath() and ensured the xpath uses prefixes.
  • Old code: add NULL as second parameter
• Added eof parameter to clicon_rpc() and clicon_rpc1() and error handling modified

Minor features

• Command-line option: Extended -l of all clixon commands with -l n which directs logging to /dev/null
• New: CLI load command for CLI syntax files (not only XML and JSON)
  • See provide support for load config of cli format along with json and xml format as save config is supported for all 3 formats
• New: Do not load clixon-restconf YANG file by default
  • See prevent clixon-restconf@2021-05-20.yang module from loading
  • Instead of always loading it, load it to datastore YANGs only if CLICON_BACKEND_RESTCONF_PROCESS is true
• YANG unique: added single descendant node ids as special case
  • This means that two variants are supported:
    • unique "a b c", ie multiple direct children
    • unique "a/b/c", ie single descendants
  • RFC 7950 Sec 7.8.3 is somewhat unclear
  • The combination is not supported

Corrected Bugs

• XPath parser: fixed some lexical issues
  • Some complexities in Section 3.7 Lexical Structure of XPath 1.0 spec as follows
  • There used to be some cornercases where function-names could not be used as nodes
  • For example, node() is a nodetest, so /node/ caused an error.
  • In the grammar these include: axisnames, nodetests, functionnames
  • The NCNames vs functionnames is now implemented according to the lexical structure section
• Fixed: Keywords containing '-' hyphen are missing from the auto-completion list
  • Fixed by disabling cligen_preference_mode. This may have other side effects.
• Fixed: Returning a string while Querying leaf-list for single entry
• Fixed: A long TLS+HTTP/2 request such as by a browser causing block of other requests.
• Fixed: Error message seen twice in some cases
• Fixed: if choice is declared with multiple elements or leaf-list with in a case scope , addition or updation is not happening as expected
  • This includes several choice/case adjustments to follow RFC 7950 Sec 7.9 better
• Fixed: HTTP/1 parse error for '/' path
• Fixed: YANG if-feature in config file of disables feature did not work, was always on
  • This does not apply to the datastore, only the config file itself.
• Fixed: YANG key list check bad performance
  • List key check did unique "xpath" lookup instead of direct child traverse
• Fixed: YANG unique single schema-nodeid required "canonical" namespace
  • E.g., a/b did not work even if there was default namespace in XML
• Disabled xpath optimization for hierarchical list
  • When XPATH_LIST_OPTIMIZE is set, patterns like y[k='3'] is optimized
  • But hierarchical lists should not be, ie when a/y[k='3'] and a is a list
• Fixed: Removed warning at startup: No YANG spec for module-set
• Fixed: HTTP/1 multiple write requests in single session appended data between writes, eg PUT+PUT.
• Fixed: Broken pipe error seen in client (cli) when backend restarts and CLICON_SOCK is recreated
• Fixed: Xpath API do not support filter data by wildcard
• Fixed: SEGV in cli show yang