Platform/pm 2138/add nginx to known proxies (#3012)

* Add nginx to known proxies

* Only add nginx proxy if standard self host deployment

* Style changes

* Add forwarded headers config to events server

* Add known proxy forwarding to missing services

* Catch DNS errors in adding nginx proxy

* Update src/SharedWeb/Utilities/ServiceCollectionExtensions.cs

Co-authored-by: Justin Baur <19896123+justindbaur@users.noreply.github.com>

---------

Co-authored-by: Justin Baur <19896123+justindbaur@users.noreply.github.com>

bitwarden_license/src/Scim/Startup.cs

@@ -93,6 +93,12 @@ public class Startup
         // Add general security headers
         app.UseMiddleware<SecurityHeadersMiddleware>();
 
+        // Forwarding Headers
+        if (globalSettings.SelfHosted)
+        {
+            app.UseForwardedHeaders(globalSettings);
+        }
+
         if (env.IsDevelopment())
         {
             app.UseDeveloperExceptionPage();

src/Events/Startup.cs

@@ -93,6 +93,12 @@ public class Startup
         // Add general security headers
         app.UseMiddleware<SecurityHeadersMiddleware>();
 
+        // Forwarding Headers
+        if (globalSettings.SelfHosted)
+        {
+            app.UseForwardedHeaders(globalSettings);
+        }
+
         if (env.IsDevelopment())
         {
             app.UseDeveloperExceptionPage();

src/Icons/Startup.cs

@@ -55,6 +55,12 @@ public class Startup
         // Add general security headers
         app.UseMiddleware<SecurityHeadersMiddleware>();
 
+        // Forwarding Headers
+        if (globalSettings.SelfHosted)
+        {
+            app.UseForwardedHeaders(globalSettings);
+        }
+
         if (env.IsDevelopment())
         {
             app.UseDeveloperExceptionPage();

src/Notifications/Startup.cs

@@ -90,6 +90,12 @@ public class Startup
         // Add general security headers
         app.UseMiddleware<SecurityHeadersMiddleware>();
 
+        // Forwarding Headers
+        if (globalSettings.SelfHosted)
+        {
+            app.UseForwardedHeaders(globalSettings);
+        }
+
         if (env.IsDevelopment())
         {
             app.UseDeveloperExceptionPage();

src/SharedWeb/Utilities/ServiceCollectionExtensions.cs

@@ -540,10 +540,17 @@ public static class ServiceCollectionExtensions
         if (!globalSettings.UnifiedDeployment)
         {
             // Trust the X-Forwarded-Host header of the nginx docker container
-            var nginxIp = Dns.GetHostEntry("nginx").AddressList.FirstOrDefault();
-            if (nginxIp != null)
+            try
             {
-                options.KnownProxies.Add(nginxIp);
+                var nginxIp = Dns.GetHostEntry("nginx")?.AddressList.FirstOrDefault();
+                if (nginxIp != null)
+                {
+                    options.KnownProxies.Add(nginxIp);
+                }
+            }
+            catch
+            {
+                // Ignore DNS errors
             }
         }