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node red server by cyberman with seq no in payload, not in port, and timezone (diff minimized)

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Marius Gripp 2019-10-01 17:28:54 +02:00
parent ba732012b9
commit 5fcb33d03d
1 changed files with 2 additions and 2 deletions
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src/Timeserver/Nodered-Timeserver.json
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@ -187,7 +187,7 @@
"type": "function", "type": "function",
"z": "449c1517.e25f4c", "z": "449c1517.e25f4c",
"name": "Timeserver Logic", "name": "Timeserver Logic",
"func": "/* LoRaWAN Timeserver\n\nconstruct 5 byte timesync_answer from gateway timestamp and node's time_sync_req\n\nbyte meaning\n1..4 current second (from epoch time 1970)\n5 1/250ths fractions of current second\n\nFPort = sequence number (taken from node's time_sync_req)\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\n// guess if we have received a valid time_sync_req command\nif (msg.payload.payload_raw.length != 1)\n return;\n\nvar deviceMsg = { payload: msg.payload.dev_id };\nvar seqNo = msg.payload.payload_raw[0];\nvar seqNoMsg = { payload: seqNo };\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) {\n var notavailMsg = { payload: \"n/a\" };\n var notimeMsg = { payload: 0xff }; \n var buf2 = Buffer.alloc(1);\n msg.payload = new Buffer(buf2.fill(0xff));\n return [notavailMsg, notavailMsg, deviceMsg, seqNoMsg, msg];}\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;\n\nlet buf = new ArrayBuffer(5);\nnew DataView(buf).setUint32(0, seconds);\nnew DataView(buf).setUint8(4, fractions);\n\nmsg.payload = new Buffer(new Uint8Array(buf));\nmsg.port = seqNo;\nvar euiMsg = { payload: eui };\nvar offsetMsg = { payload: offset };\n\nreturn [euiMsg, offsetMsg, deviceMsg, seqNoMsg, msg];", "func": "/* LoRaWAN Timeserver\n\nconstruct 5 byte timesync_answer from gateway timestamp and node's time_sync_req\n\nbyte meaning\n1..4 current second (from epoch time 1970)\n5 1/250ths fractions of current second\n\nFPort = sequence number (taken from node's time_sync_req)\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\n// guess if we have received a valid time_sync_req command\nif (msg.payload.payload_raw.length != 1)\n return;\n\nvar deviceMsg = { payload: msg.payload.dev_id };\nvar seqNo = msg.payload[0];\nvar seqNoMsg = { payload: seqNo };\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) {\n var notavailMsg = { payload: \"n/a\" };\n var notimeMsg = { payload: 0xff }; \n var buf2 = Buffer.alloc(1);\n msg.payload = new Buffer(buf2.fill(0xff));\n return [notavailMsg, notavailMsg, deviceMsg, seqNoMsg, msg];}\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;\n\nlet buf = new ArrayBuffer(7);\nnew DataView(buf).setUint8(0, seqNo);\n// Timezone (in 15min steps)\nvar timezone = 8; // CET = UTC+2h\nnew DataView(buf).setUint8(1, timezone);\nnew DataView(buf).setUint32(2, seconds);\nnew DataView(buf).setUint8(6, fractions);\n\nmsg.payload = new Buffer(new Uint8Array(buf));\nmsg.port = 9;\nvar euiMsg = { payload: eui };\nvar offsetMsg = { payload: offset };\n\nreturn [euiMsg, offsetMsg, deviceMsg, seqNoMsg, msg];",
"outputs": 5, "outputs": 5,
"noerr": 0, "noerr": 0,
"x": 350, "x": 350,