From 068ef9bc0dc62f1623a0ed85f736494edbe84731 Mon Sep 17 00:00:00 2001
From: Anna Henningsen <anna@addaleax.net>
Date: Tue, 19 Nov 2024 20:04:20 +0100
Subject: [PATCH] chore: improve logging around local HTTP server listening
 MONGOSH-1917

---
 src/log-hook.ts             | 12 ++++++++++++
 src/rfc-8252-http-server.ts | 38 ++++++++++++++++++++++++++-----------
 src/types.ts                | 18 +++++++++++++++---
 3 files changed, 54 insertions(+), 14 deletions(-)

diff --git a/src/log-hook.ts b/src/log-hook.ts
index 19999f3..1d000c7 100644
--- a/src/log-hook.ts
+++ b/src/log-hook.ts
@@ -92,6 +92,18 @@ export function hookLoggerToMongoLogWriter(
     );
   });
 
+  emitter.on('mongodb-oidc-plugin:local-listen-resolved-hostname', (ev) => {
+    log.info(
+      'OIDC-PLUGIN',
+      mongoLogId(1_002_000_028),
+      `${contextPrefix}-oidc`,
+      'Resolved hostnames for local server',
+      {
+        ...ev,
+      }
+    );
+  });
+
   emitter.on('mongodb-oidc-plugin:local-listen-failed', (ev) => {
     log.error(
       'OIDC-PLUGIN',
diff --git a/src/rfc-8252-http-server.ts b/src/rfc-8252-http-server.ts
index d6b04f4..d937367 100644
--- a/src/rfc-8252-http-server.ts
+++ b/src/rfc-8252-http-server.ts
@@ -300,14 +300,18 @@ export class RFC8252HTTPServer {
    */
   public get listeningPort(): number | undefined {
     if (this.servers.length === 0) return undefined;
-    const ports = new Set(
-      this.servers.map((srv) => (srv.address() as AddressInfo)?.port)
+    const addresses: AddressInfo[] = this.servers.map(
+      (srv) => srv.address() as AddressInfo
     );
+    const ports = new Set(addresses.map((addr) => addr.port));
     const port = ports.size === 1 && [...ports][0];
     if (typeof port !== 'number') {
+      const addressesDebugInfo = addresses
+        .map((addr) => JSON.stringify(addr))
+        .join(',');
       // Should never happen
       throw new MongoDBOIDCError(
-        `Server is listening in inconsistent state: ${[...ports].join(',')}`
+        `Server is listening in inconsistent state: ${addressesDebugInfo}`
       );
     }
     return port;
@@ -343,8 +347,11 @@ export class RFC8252HTTPServer {
       );
     }
 
+    const urlPort = this.redirectUrl.port === '' ? 80 : +this.redirectUrl.port;
+
     this.logger.emit('mongodb-oidc-plugin:local-listen-started', {
       url: this.redirectUrl.toString(),
+      urlPort,
     });
 
     // https://www.rfc-editor.org/rfc/rfc8252#section-7.3 states:
@@ -363,9 +370,18 @@ export class RFC8252HTTPServer {
     let hostname = this.redirectUrl.hostname;
     if (hostname.startsWith('[') && hostname.endsWith(']'))
       hostname = hostname.slice(1, -1);
-    const dnsResults = await dns.lookup(hostname, {
-      all: true,
-      hints: ADDRCONFIG,
+    const dnsResults = (
+      await dns.lookup(hostname, {
+        all: true,
+        hints: ADDRCONFIG,
+      })
+    ).map(({ address, family }) => ({ address, family }));
+
+    this.logger.emit('mongodb-oidc-plugin:local-listen-resolved-hostname', {
+      url: this.redirectUrl.toString(),
+      urlPort,
+      hostname,
+      interfaces: dnsResults,
     });
 
     if (dnsResults.length === 0) {
@@ -375,9 +391,6 @@ export class RFC8252HTTPServer {
     }
 
     try {
-      const urlPort =
-        this.redirectUrl.port === '' ? 80 : +this.redirectUrl.port;
-
       // Two scenarios: Either we are listening on an arbitrary port here,
       // or listening on a specific port. Using an arbitrary port has the
       // advantage that the OS will allocate a free one for us, while a
@@ -406,7 +419,7 @@ export class RFC8252HTTPServer {
           if (typeof port !== 'number') {
             // Should never happen
             throw new MongoDBOIDCError(
-              `Listening on ${dnsResults[0].address} did not return a port`
+              `Listening on ${dnsResults[0].address} (family = ${dnsResults[0].family}) did not return a port`
             );
           }
         }
@@ -429,13 +442,16 @@ export class RFC8252HTTPServer {
       await this.close();
       this.logger.emit('mongodb-oidc-plugin:local-listen-failed', {
         url: this.redirectUrl.toString(),
+        error: String(
+          err && typeof err === 'object' && 'message' in err ? err.message : err
+        ),
       });
       throw err;
     }
 
     this.logger.emit('mongodb-oidc-plugin:local-listen-succeeded', {
       url: this.listeningRedirectUrl || '',
-      interfaces: dnsResults.map((dnsResult) => dnsResult.address),
+      interfaces: dnsResults,
     });
   }
 
diff --git a/src/types.ts b/src/types.ts
index f130b72..af20bd7 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -25,11 +25,23 @@ export interface MongoDBOIDCLogEventsMap {
     method: string;
     path: string;
   }) => void;
-  'mongodb-oidc-plugin:local-listen-started': (event: { url: string }) => void;
-  'mongodb-oidc-plugin:local-listen-failed': (event: { url: string }) => void;
+  'mongodb-oidc-plugin:local-listen-started': (event: {
+    url: string;
+    urlPort: number;
+  }) => void;
+  'mongodb-oidc-plugin:local-listen-resolved-hostname': (event: {
+    url: string;
+    urlPort: number;
+    hostname: string;
+    interfaces: { family: number; address: string }[];
+  }) => void;
+  'mongodb-oidc-plugin:local-listen-failed': (event: {
+    url: string;
+    error: string;
+  }) => void;
   'mongodb-oidc-plugin:local-listen-succeeded': (event: {
     url: string;
-    interfaces: string[];
+    interfaces: { family: number; address: string }[];
   }) => void;
   'mongodb-oidc-plugin:local-server-close': (event: { url: string }) => void;
   'mongodb-oidc-plugin:open-browser': (event: {