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[UNDERTOW-2370] Guard against non-servlet ctx request with ServletNam… #1758

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[UNDERTOW-2370] Guard against non-servlet ctx request with ServletNam… #1758

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7 changes: 6 additions & 1 deletion servlet/src/main/java/io/undertow/servlet/attribute/ServletNameAttribute.java
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Original file line number Diff line number Diff line change
Expand Up @@ -35,6 +35,7 @@ public class ServletNameAttribute implements ExchangeAttribute {

public static final ExchangeAttribute INSTANCE = new ServletNameAttribute();
public static final String NAME = "Servlet Name";
public static final String UNDEFINED = "No-Servlet";

private ServletNameAttribute() {

Expand All @@ -43,7 +44,11 @@ private ServletNameAttribute() {
@Override
public String readAttribute(final HttpServerExchange exchange) {
ServletRequestContext src = exchange.getAttachment(ServletRequestContext.ATTACHMENT_KEY);
return src.getCurrentServlet().getManagedServlet().getServletInfo().getName();
if (src != null) {
return src.getCurrentServlet().getManagedServlet().getServletInfo().getName();
} else {
return UNDEFINED;
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Could you explain the reasoning behind intentionally returning "No-Servlet" here?

I was thinking that returning null would be sufficient, as it gets logged as - in the access log by default. This would also align with other ExchangeAttributes, which typically return null when a value isn't available.

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UX, looks better than "null".

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@msfm msfm Sep 11, 2025 •
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To clarify, my suggestion of returning null does not result in the string "null" being logged. Instead, the access log mechanism converts it to -, which is the standard convention for an empty value in Undertow.

My main concern is consistency. All other ExchangeAttributes (like RequestHeaderAttribute, ResponseHeaderAttribute, RemoteUserAttribute, etc.) return null and are logged as -. Introducing a custom "No-Servlet" string here would create a special case and make the logs less uniform.

For this reason, I still believe that returning null is the most appropriate approach.

}
}

@Override
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