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rmaucher pushed a commit to branch 10.1.x
in repository https://gitbox.apache.org/repos/asf/tomcat.git
The following commit(s) were added to refs/heads/10.1.x by this push:
new b24cb50f94 Resolve missing back references or variables as empty string
b24cb50f94 is described below
commit b24cb50f94455fbf7da88dcb8b801cde695fc8e3
Author: remm <[email protected]>
AuthorDate: Thu Aug 27 08:46:28 2026 +0200
Resolve missing back references or variables as empty string
This seems to be the behavior of mod_rewrite.
Tests coauthored with OpenCode.
---
.../catalina/valves/rewrite/Substitution.java | 13 ++-
.../catalina/valves/rewrite/TestRewriteValve.java | 104 +++++++++++++++++++++
webapps/docs/changelog.xml | 4 +
3 files changed, 118 insertions(+), 3 deletions(-)
diff --git a/java/org/apache/catalina/valves/rewrite/Substitution.java b/java/org/apache/catalina/valves/rewrite/Substitution.java
index 664df31c6f..dbd14634b7 100644
--- a/java/org/apache/catalina/valves/rewrite/Substitution.java
+++ b/java/org/apache/catalina/valves/rewrite/Substitution.java
@@ -101,7 +101,7 @@ public class Substitution {
@Override
public String evaluate(Matcher rule, Matcher cond, Resolver resolver) {
- String result = rule.group(n);
+ String result = (n <= rule.groupCount()) ? rule.group(n) : null;
if (result == null) {
result = "";
}
@@ -134,7 +134,8 @@ public class Substitution {
@Override
public String evaluate(Matcher rule, Matcher cond, Resolver resolver) {
- return (cond.group(n) == null ? "" : cond.group(n));
+ String result = (cond != null && n <= cond.groupCount()) ? cond.group(n) : null;
+ return (result == null) ? "" : result;
}
}
@@ -497,7 +498,13 @@ public class Substitution {
private String evaluateSubstitution(SubstitutionElement[] elements, Matcher rule, Matcher cond, Resolver resolver) {
StringBuilder buf = new StringBuilder();
for (SubstitutionElement element : elements) {
- buf.append(element.evaluate(rule, cond, resolver));
+ // Elements may return null, for example when a server variable,
+ // environment variable, SSL variable or map lookup is undefined.
+ // Like mod_rewrite, undefined values expand to an empty string.
+ String value = element.evaluate(rule, cond, resolver);
+ if (value != null) {
+ buf.append(value);
+ }
}
return buf.toString();
}
diff --git a/test/org/apache/catalina/valves/rewrite/TestRewriteValve.java b/test/org/apache/catalina/valves/rewrite/TestRewriteValve.java
index e5ac7dd1c9..3634872943 100644
--- a/test/org/apache/catalina/valves/rewrite/TestRewriteValve.java
+++ b/test/org/apache/catalina/valves/rewrite/TestRewriteValve.java
@@ -20,11 +20,14 @@ import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
import java.net.HttpURLConnection;
+import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
import jakarta.servlet.ServletException;
import jakarta.servlet.http.Cookie;
@@ -832,6 +835,107 @@ public class TestRewriteValve extends TomcatBaseTest {
}
+ @Test
+ public void testSubstitutionUnknownServerVariable() throws Exception {
+ // Unknown server variables must expand to an empty string
+ doTestRewrite("RewriteRule ^/b$ /c/undef_%{UNKNOWN_VARIABLE}", "/b", "/c/undef_");
+ }
+
+
+ @Test
+ public void testSubstitutionFailedMapLookup() throws Exception {
+ // A failed map lookup without a default value must expand to an empty string
+ doTestRewrite("RewriteMap mapa org.apache.catalina.valves.rewrite.TesterRewriteMapA\n" +
+ "RewriteRule ^/b$ /c/map_${mapa:missing}", "/b", "/c/map_");
+ }
+
+
+ @Test
+ public void testRuleBackReferenceMissingGroup() throws Exception {
+ // $1 does not exist in the pattern so it must expand to an empty string
+ doTestRewrite("RewriteRule ^/b$ /c/backref_$1", "/b", "/c/backref_");
+ }
+
+
+ @Test
+ public void testCondBackReferenceNoMatchedCond() throws Exception {
+ // There are no RewriteCond directives so %1 must expand to an empty string
+ doTestRewrite("RewriteRule ^/b$ /c/backref_%1", "/b", "/c/backref_");
+ }
+
+
+ @Test
+ public void testCondBackReferenceLexicalCondOnly() throws Exception {
+ // The condition is a lexical comparison and has no capture groups so %1 must
+ // expand to an empty string
+ doTestRewrite("RewriteCond %{REQUEST_URI} =/b\n" +
+ "RewriteRule ^/b$ /c/backref_%1", "/b", "/c/backref_");
+ }
+
+
+ @Test
+ public void testCondMatcherReflectsCurrentRequest() throws Exception {
+ // The matcher returned for a condition must reflect the result of the most
+ // recent evaluation, including that it is cleared when the pattern does not
+ // match.
+ RewriteCond condition = new RewriteCond();
+ condition.setTestString("%{QUERY_STRING}");
+ condition.setCondPattern("!^a=([0-9]+)$");
+ condition.parse(new HashMap<String, RewriteMap>());
+
+ Matcher rule = Pattern.compile(".*").matcher("/b");
+
+ // The pattern matches so the negated condition is not satisfied
+ Assert.assertFalse(condition.evaluate(rule, null, new TestResolver("a=1")));
+ Matcher m = condition.getMatcher();
+ Assert.assertNotNull(m);
+ Assert.assertEquals("1", m.group(1));
+
+ // The pattern does not match so the negated condition is satisfied and the
+ // matcher must be cleared
+ Assert.assertTrue(condition.evaluate(rule, null, new TestResolver("b=2")));
+ Assert.assertNull(condition.getMatcher());
+ }
+
+
+ private static class TestResolver extends Resolver {
+
+ private final String queryString;
+
+ private TestResolver(String queryString) {
+ this.queryString = queryString;
+ }
+
+ @Override
+ public String resolve(String key) {
+ if (key.equals("QUERY_STRING")) {
+ return queryString;
+ }
+ return "";
+ }
+
+ @Override
+ public String resolveSsl(String key) {
+ return null;
+ }
+
+ @Override
+ public String resolveHttp(String key) {
+ return "";
+ }
+
+ @Override
+ public boolean resolveResource(int type, String name) {
+ return false;
+ }
+
+ @Override
+ public Charset getUriCharset() {
+ return StandardCharsets.UTF_8;
+ }
+ }
+
+
@Test
public void testNegativePattern01() throws Exception {
doTestRewrite("RewriteRule !^/b/.* /c/", "/b", "/c/");
diff --git a/webapps/docs/changelog.xml b/webapps/docs/changelog.xml
index 898bd14b86..f89a089adf 100644
--- a/webapps/docs/changelog.xml
+++ b/webapps/docs/changelog.xml
@@ -146,6 +146,10 @@
<fix>
Ensure namespace attributes are XML escaped in WebDAV responses. (markt)
</fix>
+ <fix>
+ Resolve null or missing rewrite substitutions as an empty string, to
+ align with the mod_rewrite behavior. (remm)
+ </fix>
</changelog>
</subsection>
<subsection name="Cluster">
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