Proposal of fixing external navigation.

Author: ilonatommy

src/Components/Endpoints/src/DependencyInjection/HttpNavigationManager.cs

@@ -23,8 +23,52 @@ protected override void NavigateToCore(string uri, NavigationOptions options)
         }
         else
         {
+            if (!IsInternalUri(absoluteUriString))
+            {
+                // it's an external navigation, avoid Uri validation exception
+                BaseUri = GetBaseUriFromAbsoluteUri(absoluteUriString);
+            }
             Uri = absoluteUriString;
             NotifyLocationChanged(isInterceptedLink: false);
         }
     }
+
+    // ToDo: the following are copy-paste, consider refactoring to a common place
+    private bool IsInternalUri(string uri)
+    {
+        var normalizedBaseUri = NormalizeBaseUri(BaseUri);
+        return uri.StartsWith(normalizedBaseUri, StringComparison.OrdinalIgnoreCase);
+    }
+
+    private static string GetBaseUriFromAbsoluteUri(string absoluteUri)
+    {
+        // Find the position of the first single slash after the scheme (e.g., "https://")
+        var schemeDelimiterIndex = absoluteUri.IndexOf("://", StringComparison.Ordinal);
+        if (schemeDelimiterIndex == -1)
+        {
+            throw new ArgumentException($"The provided URI '{absoluteUri}' is not a valid absolute URI.");
+        }
+
+        // Find the end of the authority section (e.g., "https://example.com/")
+        var authorityEndIndex = absoluteUri.IndexOf('/', schemeDelimiterIndex + 3);
+        if (authorityEndIndex == -1)
+        {
+            // If no slash is found, the entire URI is the authority (e.g., "https://example.com")
+            return NormalizeBaseUri(absoluteUri + "/");
+        }
+
+        // Extract the base URI up to the authority section
+        return NormalizeBaseUri(absoluteUri.Substring(0, authorityEndIndex + 1));
+    }
+
+    private static string NormalizeBaseUri(string baseUri)
+    {
+        var lastSlashIndex = baseUri.LastIndexOf('/');
+        if (lastSlashIndex >= 0)
+        {
+            baseUri = baseUri.Substring(0, lastSlashIndex + 1);
+        }
+
+        return baseUri;
+    }
 }

src/Components/Server/src/Circuits/RemoteNavigationManager.cs

@@ -97,8 +97,14 @@ protected override void NavigateToCore(string uri, NavigationOptions options)
             }
             else
             {
+                if (!IsInternalUri(absoluteUriString))
+                {
+                    // it's an external navigation, avoid Uri validation exception
+                    BaseUri = GetBaseUriFromAbsoluteUri(absoluteUriString);
+                }
                 Uri = absoluteUriString;
                 NotifyLocationChanged(isInterceptedLink: false);
+                return;
             }
         }
 
@@ -134,6 +140,44 @@ async Task PerformNavigationAsync()
         }
     }
 
+    private bool IsInternalUri(string uri)
+    {
+        var normalizedBaseUri = NormalizeBaseUri(BaseUri);
+        return uri.StartsWith(normalizedBaseUri, StringComparison.OrdinalIgnoreCase);
+    }
+
+    private static string GetBaseUriFromAbsoluteUri(string absoluteUri)
+    {
+        // Find the position of the first single slash after the scheme (e.g., "https://")
+        var schemeDelimiterIndex = absoluteUri.IndexOf("://", StringComparison.Ordinal);
+        if (schemeDelimiterIndex == -1)
+        {
+            throw new ArgumentException($"The provided URI '{absoluteUri}' is not a valid absolute URI.");
+        }
+
+        // Find the end of the authority section (e.g., "https://example.com/")
+        var authorityEndIndex = absoluteUri.IndexOf('/', schemeDelimiterIndex + 3);
+        if (authorityEndIndex == -1)
+        {
+            // If no slash is found, the entire URI is the authority (e.g., "https://example.com")
+            return NormalizeBaseUri(absoluteUri + "/");
+        }
+
+        // Extract the base URI up to the authority section
+        return NormalizeBaseUri(absoluteUri.Substring(0, authorityEndIndex + 1));
+    }
+
+    private static string NormalizeBaseUri(string baseUri)
+    {
+        var lastSlashIndex = baseUri.LastIndexOf('/');
+        if (lastSlashIndex >= 0)
+        {
+            baseUri = baseUri.Substring(0, lastSlashIndex + 1);
+        }
+
+        return baseUri;
+    }
+
     /// <inheritdoc />
     public override void Refresh(bool forceReload = false)
     {
@@ -148,6 +192,7 @@ public override void Refresh(bool forceReload = false)
             {
                 Uri = absoluteUriString;
                 NotifyLocationChanged(isInterceptedLink: false);
+                return;
             }
         }