mirror of
https://github.com/ntop/n2n.git
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Add pubsub system to edge, with one example TEST channel
This commit is contained in:
Hamish Coleman
parent
509a8bcd14
commit
a40ed15d93
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@ -58,15 +58,23 @@ Fields:
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The maximum length of the entire line of text is 80 octets.
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All request packets should generate a reply. However, this reply may simply
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be an error.
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### Message Type
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This is a single octet that is either "r" for a read (or query) method
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call or "w" for a write (or change) method call.
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This is a single octet specifying the type:
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- "r" for a read-only method (or one that does not need change permissions)
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- "w" for a write method (or one that makes changes)
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- "s" for a subscribe method to request this socket receive some events
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To simplify the interface, the reply from both read and write calls to the
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same method is expected to contain the same data. In the case of a write
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call, the reply will contain the new state after making the requested change.
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The subscribe and events message flow works with a different set of messages.
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### Options
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The options field is a colon separated set of options for this request. Only
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@ -90,8 +98,9 @@ Where possible, the error replies will also include this tag, however some
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errors occur before the tag is parsed.
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The tag is not interpreted by the daemon, it is simply echoed back in all
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the replies. It is expected to be a short string that the client chooses
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to be unique amongst all recent or still outstanding requests.
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the replies. It is expected to be a short string that the client knows
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will be unique amongst all recent, still outstanding or subscription requests
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on a given socket.
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One possible client implementation is a number between 0 and 999, incremented
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for each request and wrapping around to zero when it is greater than 999.
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@ -128,6 +137,9 @@ e.g:
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Each UDP packet in the reply is a complete and valid JSON dictionary
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containing a fragment of information related to the entire reply.
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Reply packets are generated both in response to requests and whenever
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an event is published to a subscribed channel.
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### Common metadata
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There are two keys in each dictionary containing metadata. First
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@ -177,6 +189,47 @@ packets will be required.
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e.g:
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`{"_tag":"108","_type":"row","mode":"p2p","ip4addr":"10.135.98.84","macaddr":"86:56:21:E4:AA:39","sockaddr":"192.168.7.191:41701","desc":"client4","lastseen":1584682200}`
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### `_type: subscribed`
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Signals that the subscription request has been successfully completed.
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Any future events on the requested channel will be asynchronously sent
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as `event` packets using the same tag as the subscribe request.
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### `_type: unsubscribed`
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Only one management client can be subscribed to any given event topic, so if
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another subscribe request arrives, the older client will be sent this message
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to let them know that they have been replaced.
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(In the future, this may also be sent as a reply to a explicit unsubscribe
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request)
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### `_type: replacing`
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If a new subscription request will replace an existing one, this message is
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sent to the new client to inform them that they have replaced an older
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connection.
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### `_type: event`
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Asynchronous events will arrive with this message type, using the same tag as
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the original subscribe request. Just like with the `row` packets, the non
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metadata contents are entirely defined by the topic and the specific n2n
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version.
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## Subscribe API
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A client can subscribe to events using a request with the type of "s".
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Once a subscribe has been successfully completed, any events published
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on that channel will be forwarded to the client.
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Only one management client can be subscribed to any given event topic,
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with newer subscriptions replacing older ones.
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The special channel "debug" will receive copies of all events published.
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Note that this is for debugging of events and the packets may not have
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the same tag as the debug subscription.
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## Authentication
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Some API requests will make global changes to the running daemon and may
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@ -286,4 +286,6 @@ const char* compression_str (uint8_t cmpr);
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const char* transop_str (enum n2n_transform tr);
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void readFromMgmtSocket (n2n_edge_t *eee);
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void mgmt_event_post (enum n2n_event_topic topic, void *data);
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#endif /* _N2N_H_ */
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@ -121,6 +121,11 @@ enum sn_purge {SN_PURGEABLE = 0, SN_UNPURGEABLE = 1};
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#define N2N_EDGE_MGMT_PORT 5644
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#define N2N_SN_MGMT_PORT 5645
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enum n2n_event_topic {
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N2N_EVENT_DEBUG = 0,
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N2N_EVENT_TEST = 1,
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};
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#define N2N_MGMT_PASSWORD "n2n" /* default password for management port access (so far, json only) */
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@ -41,23 +41,37 @@ class JsonUDP():
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def _rx(self, tagstr):
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"""Wait for rx packets"""
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# TODO: there are no timeouts with any of the recv calls
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data, _ = self.sock.recvfrom(1024)
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data = json.loads(data.decode('utf8'))
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seen_begin = False
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while not seen_begin:
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# TODO: there are no timeouts with any of the recv calls
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data, _ = self.sock.recvfrom(1024)
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data = json.loads(data.decode('utf8'))
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# TODO: We assume the first packet we get will be tagged for us
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# and be either an "error" or a "begin"
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assert(data['_tag'] == tagstr)
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# TODO: We assume the first packet we get will be tagged for us
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assert(data['_tag'] == tagstr)
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if data['_type'] == 'error':
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raise ValueError('Error: {}'.format(data['error']))
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if data['_type'] == 'error':
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raise ValueError('Error: {}'.format(data['error']))
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assert(data['_type'] == 'begin')
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if data['_type'] == 'replacing':
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# a signal that we have evicted an earlier subscribe
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continue
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# Ideally, we would confirm that this is our "begin", but that
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# would need the cmd passed into this method, and that would
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# probably require parsing the cmdline passed to us :-(
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# assert(data['cmd'] == cmd)
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if data['_type'] == 'subscribe':
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return True
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if data['_type'] == 'begin':
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seen_begin = True
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# Ideally, we would confirm that this is our "begin", but that
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# would need the cmd passed into this method, and that would
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# probably require parsing the cmdline passed to us :-(
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# assert(data['cmd'] == cmd)
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continue
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raise ValueError('Unknown data type {} from '
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'edge'.format(data['_type']))
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result = list()
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error = None
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@ -105,6 +119,21 @@ class JsonUDP():
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def write(self, cmdline):
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return self._call('w', cmdline)
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def sub(self, cmdline):
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return self._call('s', cmdline)
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def readevent(self):
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self.sock.settimeout(3600)
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data, _ = self.sock.recvfrom(1024)
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data = json.loads(data.decode('utf8'))
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# assert(data['_tag'] == tagstr)
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assert(data['_type'] == 'event')
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del data['_tag']
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del data['_type']
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return data
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def str_table(rows, columns, orderby):
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"""Given an array of dicts, do a simple table print"""
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@ -203,8 +232,17 @@ def subcmd_default(rpc, args):
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cmdline = ' '.join([args.cmd] + args.args)
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if args.write:
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rows = rpc.write(cmdline)
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else:
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elif args.read:
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rows = rpc.read(cmdline)
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elif args.sub:
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if not rpc.sub(cmdline):
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raise ValueError('Could not subscribe')
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while True:
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event = rpc.readevent()
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# FIXME: violates layering..
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print(json.dumps(event, sort_keys=True, indent=4))
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else:
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raise ValueError('Unknown request type')
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return json.dumps(rows, sort_keys=True, indent=4)
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@ -228,6 +266,8 @@ def main():
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group.add_argument('--write', action='store_true',
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help='Make a write request (only to non pretty'
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'printed cmds)')
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group.add_argument('--sub', action='store_true',
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help='Make a subscribe request')
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ap.add_argument('cmd', action='store',
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help='Command to run (try "help" for list)')
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@ -236,6 +276,9 @@ def main():
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args = ap.parse_args()
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if not args.read and not args.write and not args.sub:
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args.read = True
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if args.raw or (args.cmd not in subcmds):
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func = subcmd_default
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else:
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@ -61,7 +61,7 @@ typedef struct mgmt_handler {
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* Event topic names are defined in this structure
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*/
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typedef struct mgmt_events {
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int topic; // topic number define
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enum n2n_event_topic topic;
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char *cmd;
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char *help;
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} mgmt_events_t;
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@ -80,22 +80,26 @@ typedef struct mgmt_events {
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} \
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} while(0)
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static void send_reply (mgmt_req_t *req, strbuf_t *buf, size_t msg_len) {
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// TODO: error handling
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sendto(req->eee->udp_mgmt_sock, buf->str, msg_len, 0,
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ssize_t send_reply (mgmt_req_t *req, strbuf_t *buf, size_t msg_len) {
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// TODO: better error handling (counters?)
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return sendto(req->eee->udp_mgmt_sock, buf->str, msg_len, 0,
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(struct sockaddr *) &req->sender_sock, sizeof(struct sockaddr_in));
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}
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size_t gen_json_1str (strbuf_t *buf, char *tag, char *_type, char *key, char *val) {
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return snprintf(buf->str, buf->size,
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"{"
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"\"_tag\":\"%s\","
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"\"_type\":\"%s\","
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"\"%s\":\"%s\"}\n",
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tag,
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_type,
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key,
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val);
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}
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static void send_json_1str (mgmt_req_t *req, strbuf_t *buf, char *_type, char *key, char *val) {
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size_t msg_len = snprintf(buf->str, buf->size,
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"{"
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"\"_tag\":\"%s\","
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"\"_type\":\"%s\","
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"\"%s\":\"%s\"}\n",
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req->tag,
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_type,
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key,
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val);
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size_t msg_len = gen_json_1str(buf, req->tag, _type, key, val);
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send_reply(req, buf, msg_len);
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}
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@ -112,8 +116,14 @@ static void send_json_1uint (mgmt_req_t *req, strbuf_t *buf, char *_type, char *
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send_reply(req, buf, msg_len);
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}
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static void event_debug (mgmt_req_t *req, strbuf_t *buf) {
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send_json_1str(req, buf, "event", "test", "test");
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size_t event_debug (strbuf_t *buf, char *tag, void *data) {
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traceEvent(TRACE_DEBUG, "Unexpected call to event_debug");
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return 0;
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}
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size_t event_test (strbuf_t *buf, char *tag, void *data) {
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size_t msg_len = gen_json_1str(buf, tag, "event", "test", (char *)data);
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return msg_len;
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}
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static void mgmt_error (mgmt_req_t *req, strbuf_t *buf, char *msg) {
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@ -315,6 +325,12 @@ static void mgmt_packetstats (mgmt_req_t *req, strbuf_t *buf, char *argv0, char
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send_reply(req, buf, msg_len);
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}
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static void mgmt_post_test (mgmt_req_t *req, strbuf_t *buf, char *argv0, char *argv) {
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send_json_1str(req, buf, "row", "sending", "test");
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mgmt_event_post (N2N_EVENT_TEST, argv);
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}
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static void mgmt_unimplemented (mgmt_req_t *req, strbuf_t *buf, char *argv0, char *argv) {
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mgmt_error(req, buf, "unimplemented");
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@ -334,25 +350,60 @@ static const mgmt_handler_t mgmt_handlers[] = {
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{ .cmd = "supernodes", .help = "List current supernodes", .func = mgmt_supernodes},
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{ .cmd = "timestamps", .help = "Event timestamps", .func = mgmt_timestamps},
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{ .cmd = "packetstats", .help = "traffic counters", .func = mgmt_packetstats},
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{ .cmd = "post.test", .help = "send a test event", .func = mgmt_post_test},
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{ .cmd = "help", .flags = FLAG_WROK, .help = "Show JSON commands", .func = mgmt_help},
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{ .cmd = "help.events", .help = "Show available Subscribe topics", .func = mgmt_help_events},
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};
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/* Current subscriber for each event topic */
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static mgmt_req_t mgmt_event_subscribers[] = {
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[0] = { .eee = NULL, .type = N2N_MGMT_UNKNOWN, .tag = "\0" },
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[N2N_EVENT_DEBUG] = { .eee = NULL, .type = N2N_MGMT_UNKNOWN, .tag = "\0" },
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[N2N_EVENT_TEST] = { .eee = NULL, .type = N2N_MGMT_UNKNOWN, .tag = "\0" },
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};
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/* Map topic number to function */
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static const void (*mgmt_events[])(mgmt_req_t *req, strbuf_t *buf) = {
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[0] = event_debug,
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static const size_t (*mgmt_events[])(strbuf_t *buf, char *tag, void *data) = {
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[N2N_EVENT_DEBUG] = event_debug,
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[N2N_EVENT_TEST] = event_test,
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};
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/* Allow help and subscriptions to use topic name */
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static const mgmt_events_t mgmt_event_names[] = {
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{ .cmd = "debug", .topic = 0, .help = "All events - for event debugging"},
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{ .cmd = "debug", .topic = N2N_EVENT_DEBUG, .help = "All events - for event debugging"},
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{ .cmd = "test", .topic = N2N_EVENT_TEST, .help = "Used only by post.test"},
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};
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void mgmt_event_post (enum n2n_event_topic topic, void *data) {
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mgmt_req_t *debug = &mgmt_event_subscribers[N2N_EVENT_DEBUG];
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mgmt_req_t *sub = &mgmt_event_subscribers[topic];
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if( sub->type != N2N_MGMT_SUB && debug->type != N2N_MGMT_SUB) {
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// If neither of this topic or the debug topic have a subscriber
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// then we dont need to do any work
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return;
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}
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char buf_space[100];
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strbuf_t *buf;
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STRBUF_INIT(buf, buf_space);
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char *tag;
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if (sub->type == N2N_MGMT_SUB) {
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tag = sub->tag;
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} else {
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tag = debug->tag;
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}
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size_t msg_len = mgmt_events[topic](buf, tag, data);
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if (sub->type == N2N_MGMT_SUB) {
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send_reply(sub, buf, msg_len);
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}
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if (debug->type == N2N_MGMT_SUB) {
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send_reply(debug, buf, msg_len);
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}
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}
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static void mgmt_help_events (mgmt_req_t *req, strbuf_t *buf, char *argv0, char *argv) {
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size_t msg_len;
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@ -364,11 +415,11 @@ static void mgmt_help_events (mgmt_req_t *req, strbuf_t *buf, char *argv0, char
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char host[40];
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char serv[6];
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if(getnameinfo(
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(struct sockaddr *)&sub->sender_sock, sizeof(sub->sender_sock),
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host, sizeof(host),
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serv, sizeof(serv),
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NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
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if((sub->type != N2N_MGMT_SUB) ||
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getnameinfo((struct sockaddr *)&sub->sender_sock, sizeof(sub->sender_sock),
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host, sizeof(host),
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serv, sizeof(serv),
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NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
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host[0] = '?';
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host[1] = 0;
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serv[0] = '?';
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@ -533,7 +584,23 @@ static void handleMgmtJson (mgmt_req_t *req, char *udp_buf, const int recvlen) {
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}
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if(req->type == N2N_MGMT_SUB) {
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mgmt_error(req, buf, "unimplemented");
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int handler;
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lookup_handler(handler, mgmt_event_names, argv0);
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if(handler == -1) {
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mgmt_error(req, buf, "unknowntopic");
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return;
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}
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int topic = mgmt_event_names[handler].topic;
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if(mgmt_event_subscribers[topic].type == N2N_MGMT_SUB) {
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send_json_1str(&mgmt_event_subscribers[topic], buf,
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"unsubscribed", "topic", argv0);
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send_json_1str(req, buf, "replacing", "topic", argv0);
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}
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memcpy(&mgmt_event_subscribers[topic], req, sizeof(*req));
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send_json_1str(req, buf, "subscribe", "topic", argv0);
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return;
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}
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