initial commit

.eslintrc.js

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+module.exports = {
+  env: {
+    node: true,
+    commonjs: true,
+    es2021: true,
+  },
+  extends: ['airbnb', 'prettier'],
+  parserOptions: {
+    ecmaVersion: 'latest',
+  },
+  rules: {
+    'prefer-destructuring': 'off',
+    'no-bitwise': 'off',
+    'class-methods-use-this': 'off',
+    'import/extensions': 'off',
+    'import/no-relative-packages': 'off',
+  },
+};

.gitignore

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+node_modules

.nvmrc

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+v18.17.1

.prettierignore

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+*.md
+*.min.*

.prettierrc.js

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+module.exports = {
+  trailingComma: 'es5',
+  tabWidth: 2,
+  semi: true,
+  singleQuote: true,
+  bracketSameLine: true,
+  printWidth: 120,
+};

.vscode/extensions.json

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+{
+  "recommendations": ["esbenp.prettier-vscode"]
+}

.vscode/settings.json

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+{
+  "editor.defaultFormatter": "esbenp.prettier-vscode",
+  "editor.formatOnSave": true,
+  "editor.codeActionsOnSave": {
+    "source.fixAll": true,
+    "source.organizeImports": true
+  }
+}

README.md

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+# psn-js
+**!!DISCLAIMER!!**
+
+This library is still a work-in-progress. I have gotten quick proof-of-concept working and complete implementation of the [PosiStageNet](https://github.com/vyv/psn-cpp/blob/master/doc/PosiStageNetprotocol_v2.03_2019_09_09.pdf) protocol is still being worked on. Please report anything you see that is not in compliance with the protocol. 

example.js

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+const dgram = require('dgram');
+const { Decoder } = require('.');
+
+const client = dgram.createSocket('udp4');
+
+const psnDecoder = new Decoder();
+
+client.on('listening', () => {
+  const address = client.address();
+  client.setBroadcast(true);
+  client.setMulticastTTL(128);
+  client.addMembership('236.10.10.10');
+});
+
+client.on('message', (message, remote) => {
+  psnDecoder.decode(message);
+});
+
+client.bind(56565, '0.0.0.0');

index.js

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+/* eslint-disable no-param-reassign */
+const { Parser } = require('binary-parser');
+const psnParser = require('./parsers/index.js');
+const { PSN_DATA_TRACKER_FIELD_PARSER } = require('./parsers/data/index.js');
+
+const DATA_PACKET = 0x6755;
+const INFO_PACKET = 0x6756;
+
+class Decoder {
+  constructor() {
+    this.info = {};
+
+    this.data = {
+      trackers: {},
+    };
+  }
+
+  // TODO(jwetzell): support multiple frame packets this might require some rework of how chunks are assumed
+  decode(packetBuf) {
+    const packet = psnParser(packetBuf);
+    if (packet.id === INFO_PACKET) {
+      if (packet.chunk_data?.tracker_list?.trackers) {
+        packet.chunk_data?.tracker_list?.trackers.forEach((tracker) => {
+          if (this.data.trackers[tracker.id] === undefined) {
+            this.data.trackers[tracker.id] = {};
+          }
+          this.data.trackers[tracker.id] = {
+            ...this.data.trackers[tracker.id],
+            id: tracker.id,
+            name: tracker.tracker_name.tracker_name,
+          };
+        });
+      }
+    } else if (packet.id === DATA_PACKET) {
+      if (packet.chunk_data?.tracker_list?.trackers) {
+        packet.chunk_data?.tracker_list?.trackers.forEach((tracker) => {
+          if (this.data.trackers[tracker.id] === undefined) {
+            this.data.trackers[tracker.id] = {};
+          }
+          this.data.trackers[tracker.id] = {
+            ...this.data.trackers[tracker.id],
+            id: tracker.id,
+          };
+
+          if (tracker.data && tracker.data_len > 0) {
+            const fields = new Parser()
+              .array('fields', {
+                type: PSN_DATA_TRACKER_FIELD_PARSER,
+                lengthInBytes: tracker.data_len,
+              })
+              .parse(tracker.data);
+            if (fields.fields) {
+              fields.fields.forEach((field) => {
+                if (field.data) {
+                  this.data.trackers[tracker.id] = {
+                    ...this.data.trackers[tracker.id],
+                    ...field.data,
+                  };
+                }
+              });
+            }
+            tracker.fields = fields.fields;
+            delete tracker.data;
+          }
+        });
+      }
+    }
+    return packet;
+  }
+}
+
+module.exports = {
+  Decoder,
+};

package.json

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+{
+  "name": "posistagenet",
+  "version": "0.0.1",
+  "description": "",
+  "main": "index.js",
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1"
+  },
+  "author": "",
+  "license": "ISC",
+  "devDependencies": {
+    "eslint": "^8.48.0",
+    "eslint-config-airbnb": "^19.0.4",
+    "eslint-config-prettier": "^9.0.0",
+    "prettier": "^3.0.3"
+  },
+  "dependencies": {
+    "binary-parser": "^2.2.1"
+  }
+}

parsers/common/index.js

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+const Parser = require('binary-parser').Parser;
+
+const PSN_PACKET_HEADER_PARSER = new Parser()
+  .uint16le('id')
+  .uint16le('data_len', {
+    formatter: (item) => {
+      const binary = item.toString(2).padStart(16, '0');
+      return Number.parseInt(binary.substring(1), 2);
+    },
+  })
+  .seek(-2)
+  .uint16le('has_subchunks', {
+    formatter: (item) => {
+      const binary = item.toString(2).padStart(16, '0');
+      return binary.charAt(0) === '1';
+    },
+  })
+  .uint64le('packet_timestamp')
+  .uint8('version_high')
+  .uint8('version_low')
+  .uint8('frame_id')
+  .uint8('frame_packet_count')
+  .seek(4);
+
+module.exports = {
+  PSN_PACKET_HEADER_PARSER,
+};

parsers/data/index.js

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+const { PSN_PACKET_HEADER_PARSER } = require('../common');
+const Parser = require('binary-parser').Parser;
+
+const PSN_DATA_TRACKER_FIELD_PARSER = new Parser()
+  .uint16le('id')
+  .uint16le('data_len', {
+    formatter: (item) => {
+      const binary = item.toString(2).padStart(16, '0');
+      return Number.parseInt(binary.substring(1), 2);
+    },
+  })
+  .seek(-2)
+  .uint16le('has_subchunks', {
+    formatter: (item) => {
+      const binary = item.toString(2).padStart(16, '0');
+      return binary.charAt(0) === '1';
+    },
+  })
+  .choice('data', {
+    tag: 'id',
+    choices: {
+      0x0000: new Parser().floatle('pos_x').floatle('pos_y').floatle('pos_z'),
+      0x0001: new Parser().floatle('speed_x').floatle('speed_y').floatle('speed_z'),
+      0x0002: new Parser().floatle('ori_x').floatle('ori_y').floatle('ori_z'),
+      0x0003: new Parser().floatle('validity'),
+      0x0004: new Parser().floatle('accel_x').floatle('accel_y').floatle('accel_z'),
+      0x0005: new Parser().floatle('trgtpos_x').floatle('trgtpos_y').floatle('trgtpos_z'),
+      0x0006: new Parser().uint64le('tracker_timestamp'),
+    },
+  });
+
+const PSN_DATA_TRACKER_PARSER = new Parser()
+  .uint16le('id')
+  .uint16le('data_len', {
+    formatter: (item) => {
+      const binary = item.toString(2).padStart(16, '0');
+      return Number.parseInt(binary.substring(1), 2);
+    },
+  })
+  .seek(-2)
+  .uint16le('has_subchunks', {
+    formatter: (item) => {
+      const binary = item.toString(2).padStart(16, '0');
+      return binary.charAt(0) === '1';
+    },
+  })
+  .buffer('data', {
+    length: 'data_len',
+  });
+
+const PSN_DATA_TRACKER_LIST_PARSER = new Parser()
+  .uint16le('id')
+  .uint16le('data_len', {
+    formatter: (item) => {
+      const binary = item.toString(2).padStart(16, '0');
+      return Number.parseInt(binary.substring(1), 2);
+    },
+  })
+  .seek(-2)
+  .uint16le('has_subchunks', {
+    formatter: (item) => {
+      const binary = item.toString(2).padStart(16, '0');
+      return binary.charAt(0) === '1';
+    },
+  })
+  .array('trackers', { type: PSN_DATA_TRACKER_PARSER, lengthInBytes: 'data_len' });
+
+const PSN_DATA_CHUNK_DATA_PARSER = new Parser()
+  .nest('packet_header', { type: PSN_PACKET_HEADER_PARSER })
+  .nest('tracker_list', { type: PSN_DATA_TRACKER_LIST_PARSER });
+
+module.exports = {
+  PSN_DATA_CHUNK_DATA_PARSER,
+  PSN_DATA_TRACKER_FIELD_PARSER,
+  PSN_DATA_TRACKER_LIST_PARSER,
+  PSN_DATA_TRACKER_PARSER,
+};

parsers/index.js

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+const { PSN_DATA_CHUNK_DATA_PARSER } = require('./data');
+const { PSN_INFO_CHUNK_DATA_PARSER } = require('./info');
+
+const Parser = require('binary-parser').Parser;
+
+const PSN_PACKET_PARSER = new Parser()
+  .uint16le('id')
+  .uint16le('data_len', {
+    formatter: (item) => {
+      const binary = item.toString(2).padStart(16, '0');
+      return Number.parseInt(binary.substring(1), 2);
+    },
+  })
+  .seek(-2)
+  .uint16le('has_subchunks', {
+    formatter: (item) => {
+      const binary = item.toString(2).padStart(16, '0');
+      return binary.charAt(0) === '1';
+    },
+  })
+  .choice('chunk_data', {
+    tag: 'id',
+    choices: {
+      0x6755: PSN_DATA_CHUNK_DATA_PARSER,
+      0x6756: PSN_INFO_CHUNK_DATA_PARSER,
+    },
+  });
+
+module.exports = (buffer) => PSN_PACKET_PARSER.parse(buffer);

parsers/info/index.js

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+const { PSN_PACKET_HEADER_PARSER } = require('../common');
+
+const Parser = require('binary-parser').Parser;
+
+const PSN_INFO_SYSTEM_NAME_PARSER = new Parser()
+  .uint16le('id')
+  .uint16le('data_len', {
+    formatter: (item) => {
+      const binary = item.toString(2).padStart(16, '0');
+      return Number.parseInt(binary.substring(1), 2);
+    },
+  })
+  .seek(-2)
+  .uint16le('has_subchunks', {
+    formatter: (item) => {
+      const binary = item.toString(2).padStart(16, '0');
+      return binary.charAt(0) === '1';
+    },
+  })
+  .string('system_name', { length: 'data_len' });
+
+const PSN_INFO_TRACKER_NAME_PARSER = new Parser()
+  .uint16le('id')
+  .uint16le('data_len', {
+    formatter: (item) => {
+      const binary = item.toString(2).padStart(16, '0');
+      return Number.parseInt(binary.substring(1), 2);
+    },
+  })
+  .seek(-2)
+  .uint16le('has_subchunks', {
+    formatter: (item) => {
+      const binary = item.toString(2).padStart(16, '0');
+      return binary.charAt(0) === '1';
+    },
+  })
+  .string('tracker_name', { length: 'data_len' });
+
+const PSN_INFO_TRACKER_PARSER = new Parser()
+  .uint16le('id')
+  .uint16le('data_len', {
+    formatter: (item) => {
+      const binary = item.toString(2).padStart(16, '0');
+      return Number.parseInt(binary.substring(1), 2);
+    },
+  })
+  .seek(-2)
+  .uint16le('has_subchunks', {
+    formatter: (item) => {
+      const binary = item.toString(2).padStart(16, '0');
+      return binary.charAt(0) === '1';
+    },
+  })
+  .nest('tracker_name', {
+    type: PSN_INFO_TRACKER_NAME_PARSER,
+  });
+
+const PSN_INFO_TRACKER_LIST_PARSER = new Parser()
+  .uint16le('id')
+  .uint16le('data_len', {
+    formatter: (item) => {
+      const binary = item.toString(2).padStart(16, '0');
+      return Number.parseInt(binary.substring(1), 2);
+    },
+  })
+  .seek(-2)
+  .uint16le('has_subchunks', {
+    formatter: (item) => {
+      const binary = item.toString(2).padStart(16, '0');
+      return binary.charAt(0) === '1';
+    },
+  })
+  .array('trackers', { type: PSN_INFO_TRACKER_PARSER, lengthInBytes: 'data_len' });
+
+const PSN_INFO_CHUNK_DATA_PARSER = new Parser()
+  .nest('packet_header', { type: PSN_PACKET_HEADER_PARSER })
+  .nest('system_name', { type: PSN_INFO_SYSTEM_NAME_PARSER })
+  .nest('tracker_list', { type: PSN_INFO_TRACKER_LIST_PARSER });
+
+module.exports = {
+  PSN_INFO_SYSTEM_NAME_PARSER,
+  PSN_INFO_TRACKER_NAME_PARSER,
+  PSN_INFO_TRACKER_PARSER,
+  PSN_INFO_TRACKER_LIST_PARSER,
+  PSN_INFO_CHUNK_DATA_PARSER,
+};