Synnefo » snf-ganeti

Wire protocol

^^^^^^^^^^^^^

A confd query will look like this, on the wire::

  {

    "msg": "{\"type\": 1,

             \"rsalt\": \"9aa6ce92-8336-11de-af38-001d093e835f\",

             \"protocol\": 1,

             \"query\": \"node1.example.com\"}\n",

    "salt": "1249637704",

    "hmac": "4a4139b2c3c5921f7e439469a0a45ad200aead0f"

  }

Detailed explanation of the various fields:

- 'msg' contains a JSON-encoded query, its fields are:

  - 'protocol', integer, is the confd protocol version (initially just

    constants.CONFD_PROTOCOL_VERSION, with a value of 1)

  - 'type', integer, is the query type. For example "node role by name" or

    "node primary ip by instance ip". Constants will be provided for the actual

    available query types.

  - 'query', string, is the search key. For example an ip, or a node name.

  - 'rsalt', string, is the required response salt. The client must use it to

    recognize which answer it's getting.

- 'salt' must be the current unix timestamp, according to the client. Servers

  can refuse messages which have a wrong timing, according to their

  configuration and clock.

- 'hmac' is an hmac signature of salt+msg, with the cluster hmac key

If an answer comes back (which is optional, since confd works over UDP) it will

be in this format::

  {

    "msg": "{\"status\": 0,

             \"answer\": 0,

             \"serial\": 42,

             \"protocol\": 1}\n",

    "salt": "9aa6ce92-8336-11de-af38-001d093e835f",

    "hmac": "aaeccc0dff9328fdf7967cb600b6a80a6a9332af"

  }

Where:

- 'msg' contains a JSON-encoded answer, its fields are:

  - 'protocol', integer, is the confd protocol version (initially just

    constants.CONFD_PROTOCOL_VERSION, with a value of 1)

  - 'status', integer, is the error code. Initially just 0 for 'ok' or '1' for

    'error' (in which case answer contains an error detail, rather than an

    answer), but in the future it may be expanded to have more meanings (eg: 2,

    the answer is compressed)

  - 'answer', is the actual answer. Its type and meaning is query specific. For

    example for "node primary ip by instance ip" queries it will be a string

    containing an IP address, for "node role by name" queries it will be an

    integer which encodes the role (master, candidate, drained, offline)

    according to constants.

- 'salt' is the requested salt from the query. A client can use it to recognize

  what query the answer is answering.

- 'hmac' is an hmac signature of salt+msg, with the cluster hmac key