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Timeserver: filter gateway with ms timestamp

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This commit is contained in:
Verkehrsrot 2019-03-24 23:23:00 +01:00
parent f7aede199d
commit d4ddb4811f
1 changed files with 8 additions and 33 deletions
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41
src/TTN/Nodered-Timeserver.json → src/Timeserver/Nodered-Timeserver.json
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@ -153,7 +153,7 @@
"y": 200, "y": 200,
"wires": [ "wires": [
[ [
"f868bce2.dde67" "831ab883.d6a238"
] ]
] ]
}, },
@ -182,37 +182,12 @@
"y": 40, "y": 40,
"wires": [] "wires": []
}, },
{
"id": "f868bce2.dde67",
"type": "switch",
"z": "449c1517.e25f4c",
"name": "Timechecker",
"property": "payload.metadata.gateways[0].time",
"propertyType": "msg",
"rules": [
{
"t": "lte",
"v": "payload.metadata.time",
"vt": "msg"
}
],
"checkall": "true",
"repair": false,
"outputs": 1,
"x": 590,
"y": 200,
"wires": [
[
"831ab883.d6a238"
]
]
},
{ {
"id": "831ab883.d6a238", "id": "831ab883.d6a238",
"type": "function", "type": "function",
"z": "449c1517.e25f4c", "z": "449c1517.e25f4c",
"name": "Generate Time Answer", "name": "Generate Time Answer",
"func": "/* LoRaWAN Timeserver\n\nconstruct 6 byte timesync_answer from gateway timestamp and node's time_sync_req\n\nbyte meaning\n0 sequence number (taken from node's time_sync_req)\n1..4 current second (from epoch time 1970)\n5 1/250ths fractions of current second\n\n*/\n\nfunction timecompare(a, b) {\n \n const timeA = a.time;\n const timeB = b.time;\n\n let comparison = 0;\n if (timeA > timeB) {\n comparison = 1;\n } else if (timeA < timeB) {\n comparison = -1;\n }\n return comparison;\n}\n\nlet confidence = 2000; // max millisecond diff gateway time to server time\n\nvar deviceMsg = { payload: msg.payload.dev_id };\nvar gateways = msg.payload.metadata.gateways;\nvar gateway_time = gateways.map(gw => {\n return {\n time: new Date(gw.time),\n eui: gw.gtw_id,\n }\n });\nvar server_time = new Date(msg.payload.metadata.time);\n\n// validate all gateway timestamps against lorawan server_time (which is assumed to be recent)\nvar gw_timestamps = gateway_time.filter(function (element) {\n return ((element.time > (server_time - confidence) && element.time <= server_time));\n});\n\n// if no timestamp left, we have no valid one and exit\nif (gw_timestamps.length === 0) return [\"n/a\", \"n/a\", deviceMsg, 0xff];\n\n// sort time array in ascending order to find most recent timestamp for time answer\ngw_timestamps.sort(timecompare);\n\nvar timestamp = gw_timestamps[0].time;\nvar eui = gw_timestamps[0].eui;\nvar offset = server_time - timestamp;\n\nvar seconds = Math.floor(timestamp/1000);\nvar fractions = (timestamp % 1000) / 4;\nvar seqno = msg.payload.payload_raw[0];\n\nlet buf = new ArrayBuffer(6);\nnew DataView(buf).setUint8(0, seqno);\nnew DataView(buf).setUint32(1, seconds);\nnew DataView(buf).setUint8(5, fractions);\n\nmsg.payload = new Buffer(new Uint8Array(buf));\nvar euiMsg = { payload: eui };\nvar offsetMsg = { payload: offset };\n\nreturn [euiMsg, offsetMsg, deviceMsg, msg];", "func": "/* LoRaWAN Timeserver\n\nconstruct 6 byte timesync_answer from gateway timestamp and node's time_sync_req\n\nbyte meaning\n0 sequence number (taken from node's time_sync_req)\n1..4 current second (from epoch time 1970)\n5 1/250ths fractions of current second\n\n*/\n\nfunction timecompare(a, b) {\n \n const timeA = a.time;\n const timeB = b.time;\n\n let comparison = 0;\n if (timeA > timeB) {\n comparison = 1;\n } else if (timeA < timeB) {\n comparison = -1;\n }\n return comparison;\n}\n\nlet confidence = 2000; // max millisecond diff gateway time to server time\n\nvar deviceMsg = { payload: msg.payload.dev_id };\nvar gateway_list = msg.payload.metadata.gateways;\n\n// filter all gateway timestamps that have milliseconds part (which we assume have a \".\")\nvar gateways = gateway_list.filter(function (element) {\n return (element.time.includes(\".\"));\n});\n\nvar gateway_time = gateways.map(gw => {\n return {\n time: new Date(gw.time),\n eui: gw.gtw_id,\n }\n });\nvar server_time = new Date(msg.payload.metadata.time);\n\n// validate all gateway timestamps against lorawan server_time (which is assumed to be recent)\nvar gw_timestamps = gateway_time.filter(function (element) {\n return ((element.time > (server_time - confidence) && element.time <= server_time));\n});\n\n// if no timestamp left, we have no valid one and exit\nif (gw_timestamps.length === 0) return [\"n/a\", \"n/a\", deviceMsg, 0xff];\n\n// sort time array in ascending order to find most recent timestamp for time answer\ngw_timestamps.sort(timecompare);\n\nvar timestamp = gw_timestamps[0].time;\nvar eui = gw_timestamps[0].eui;\nvar offset = server_time - timestamp;\n\nvar seconds = Math.floor(timestamp/1000);\nvar fractions = (timestamp % 1000) / 4;\nvar seqno = msg.payload.payload_raw[0];\n\nlet buf = new ArrayBuffer(6);\nnew DataView(buf).setUint8(0, seqno);\nnew DataView(buf).setUint32(1, seconds);\nnew DataView(buf).setUint8(5, fractions);\n\nmsg.payload = new Buffer(new Uint8Array(buf));\nvar euiMsg = { payload: eui };\nvar offsetMsg = { payload: offset };\n\nreturn [euiMsg, offsetMsg, deviceMsg, msg];",
"outputs": 4, "outputs": 4,
"noerr": 0, "noerr": 0,
"x": 360, "x": 360,
@ -251,7 +226,7 @@
"tostatus": true, "tostatus": true,
"complete": "payload", "complete": "payload",
"x": 700, "x": 700,
"y": 280, "y": 240,
"wires": [], "wires": [],
"icon": "node-red/bridge.png" "icon": "node-red/bridge.png"
}, },
@ -268,7 +243,7 @@
"format": "{{msg.payload}}", "format": "{{msg.payload}}",
"layout": "col-center", "layout": "col-center",
"x": 810, "x": 810,
"y": 336, "y": 300,
"wires": [] "wires": []
}, },
{ {
@ -294,7 +269,7 @@
"seg1": "", "seg1": "",
"seg2": "", "seg2": "",
"x": 710, "x": 710,
"y": 416, "y": 380,
"wires": [] "wires": []
}, },
{ {
@ -310,7 +285,7 @@
"format": "{{msg.payload}}", "format": "{{msg.payload}}",
"layout": "col-center", "layout": "col-center",
"x": 700, "x": 700,
"y": 376, "y": 340,
"wires": [] "wires": []
}, },
{ {
@ -322,7 +297,7 @@
"outputs": 1, "outputs": 1,
"noerr": 0, "noerr": 0,
"x": 670, "x": 670,
"y": 336, "y": 300,
"wires": [ "wires": [
[ [
"8712a5ac.ed18e8" "8712a5ac.ed18e8"
@ -342,7 +317,7 @@
"format": "{{msg.payload}}", "format": "{{msg.payload}}",
"layout": "col-center", "layout": "col-center",
"x": 700, "x": 700,
"y": 456, "y": 420,
"wires": [] "wires": []
}, },
{ {