Merge pull request #340 from freasy/feature/refactor_mdns_response

refactoring mdns request parsing
ExpressLRS · May 23, 2022 · f62c7be · f62c7be
2 parents 6258532 + d6a364e
commit f62c7be
Showing 1 changed file with 88 additions and 76 deletions.
diff --git a/src/api/src/services/MulticastDns/index.ts b/src/api/src/services/MulticastDns/index.ts
@@ -1,6 +1,7 @@
 import { Service } from 'typedi';
 import * as http from 'http';
 import makeMdns, { ResponsePacket } from 'multicast-dns';
+import { SrvAnswer, StringAnswer, TxtAnswer } from 'dns-packet';
 import MulticastDnsInformation from '../../models/MulticastDnsInformation';
 import { LoggerService } from '../../logger';
 import MulticastDnsEventType from '../../models/enum/MulticastDnsEventType';
@@ -118,87 +119,98 @@ export default class MulticastDnsService {
   private handleMulticastDnsResponse(response: ResponsePacket) {
     const items = [...response.answers, ...response.additionals];
 
-    // check if any of the answers on the response have a name that starts with
-    // 'elrs_', which indicates that it is an elers device
-    const isElrs = !!items.find((item: any) => item.name.startsWith('elrs_'));
-
-    if (isElrs) {
-      const txtResponse: any = items.find((answer) => answer.type === 'TXT');
-
-      const aResponse: any = items.find((answer) => answer.type === 'A');
-
-      const srvResponse: any = items.find((answer) => answer.type === 'SRV');
+    const txtResponse: TxtAnswer = items.find(
+      (answer) => answer.type === 'TXT'
+    ) as TxtAnswer;
+
+    if (txtResponse) {
+      let options: UserDefine[] = [];
+      let version = '';
+      let target = '';
+      let type = '';
+      let vendor = '';
+      let deviceName = '';
+
+      if (Array.isArray(txtResponse.data)) {
+        txtResponse.data.forEach((i) => {
+          if (i instanceof Buffer) {
+            const dataItem = i.toString('utf-8');
+            const delimPos = dataItem.indexOf('=');
+            const key = dataItem.substring(0, delimPos);
+            const value = dataItem.substring(delimPos + 1);
+
+            switch (key) {
+              case 'options':
+                options = this.parseOptions(value);
+                break;
+              case 'version':
+                version = value;
+                break;
+              case 'target':
+                target = value;
+                break;
+              case 'type':
+                type = value;
+                break;
+              case 'vendor':
+                vendor = value;
+                break;
+              case 'device':
+                deviceName = value;
+                break;
+              default:
+                break;
+            }
+          }
+        });
+      }
 
-      if (txtResponse && aResponse && srvResponse) {
-        const dns: string = srvResponse.data?.target;
-        const port: number = srvResponse.data?.port;
-        const ip: string = aResponse.data;
-        const name: string = txtResponse.name?.substring(
+      if (vendor === 'elrs') {
+        const name = txtResponse.name?.substring(
           0,
           txtResponse.name.indexOf('.')
         );
-        let options: UserDefine[] = [];
-        let version = '';
-        let target = '';
-        let type = '';
-        let vendor = '';
-        let deviceName = '';
-
-        if (Array.isArray(txtResponse.data)) {
-          txtResponse.data.forEach((item: any) => {
-            if (item instanceof Buffer) {
-              const dataItem = item.toString('utf-8');
-              const delimPos = dataItem.indexOf('=');
-              const key = dataItem.substring(0, delimPos);
-              const value = dataItem.substring(delimPos + 1);
-
-              switch (key) {
-                case 'options':
-                  options = this.parseOptions(value);
-                  break;
-                case 'version':
-                  version = value;
-                  break;
-                case 'target':
-                  target = value;
-                  break;
-                case 'type':
-                  type = value;
-                  break;
-                case 'vendor':
-                  vendor = value;
-                  break;
-                case 'device':
-                  deviceName = value;
-                  break;
-                default:
-                  break;
-              }
-            }
-          });
-        }
-
-        const mdnsInformation: MulticastDnsInformation = {
-          name,
-          dns,
-          ip,
-          options,
-          version,
-          target,
-          type,
-          vendor,
-          port,
-          deviceName,
-        };
 
-        if (!this.devices[name]) {
-          this.devices[name] = mdnsInformation;
-          this.notifications.sendDeviceAdded(mdnsInformation);
-        } else if (
-          JSON.stringify(this.devices[name]) !== JSON.stringify(mdnsInformation)
-        ) {
-          this.devices[name] = mdnsInformation;
-          this.notifications.sendDeviceUpdated(mdnsInformation);
+        const srvResponse: SrvAnswer = items.find(
+          (answer) => answer.type === 'SRV'
+        ) as SrvAnswer;
+
+        if (srvResponse) {
+          const dns: string = srvResponse.data?.target;
+          const port: number = srvResponse.data?.port;
+
+          const aResponse: StringAnswer = items.find(
+            (answer) =>
+              answer.type === 'A' && answer.name === srvResponse.data.target
+          ) as StringAnswer;
+
+          if (aResponse) {
+            const ip: string = aResponse.data;
+
+            const mdnsInformation: MulticastDnsInformation = {
+              name,
+              dns,
+              ip,
+              options,
+              version,
+              target,
+              type,
+              vendor,
+              port,
+              deviceName,
+            };
+
+            if (!this.devices[name]) {
+              this.devices[name] = mdnsInformation;
+              this.notifications.sendDeviceAdded(mdnsInformation);
+            } else if (
+              JSON.stringify(this.devices[name]) !==
+              JSON.stringify(mdnsInformation)
+            ) {
+              this.devices[name] = mdnsInformation;
+              this.notifications.sendDeviceUpdated(mdnsInformation);
+            }
+          }
         }
       }
     }