Rewrite any prefix subdomain like *.example.com

Signed-off-by: Valentin Delaye <jonesbusy@users.noreply.github.com>

Author: jonesbusy

src/main/java/land/oras/auth/RegistriesConf.java

@@ -197,19 +197,41 @@ public ContainerRef rewrite(ContainerRef ref) {
             return ref;
         }
         // No rewrite possible if location and prefix are not set
-        String registry = matchingConfig.get().location();
+        String location = matchingConfig.get().location();
         String prefix = matchingConfig.get().prefix();
-        if (registry == null || registry.isBlank() || prefix == null || prefix.isBlank()) {
+        if (location == null || location.isBlank() || prefix == null || prefix.isBlank()) {
             return ref;
         }
         String currentRefString = ref.toString();
-        String rewrittenRefString = currentRefString.replaceFirst(prefix, registry);
+        String rewrittenRefString;
+
+        // Replace all subdomain if prefix starts with "*." (e.g., *.example.com → my-registry.com)
+        if (prefix.startsWith("*.")) {
+
+            // The subdomain replacement can include an optional path
+            int firtSlashIndex = prefix.indexOf('/');
+            String prefixPath = firtSlashIndex < 0 ? "" : prefix.substring(firtSlashIndex);
+
+            // Remove matched host + optional prefixPath
+            String remainder = currentRefString.substring(ref.getRegistry().length());
+            if (!prefixPath.isEmpty() && remainder.startsWith(prefixPath)) {
+                remainder = remainder.substring(prefixPath.length());
+            }
+
+            rewrittenRefString = location + remainder;
+        }
+
+        // Just replace the prefix with the location (e.g., docker.io/library → my-registry.com/library)
+        else {
+            rewrittenRefString = location + currentRefString.substring(prefix.length());
+        }
+
         LOG.debug(
                 "Rewriting container reference from '{}' to '{}' using registry config with prefix '{}' and location '{}'",
                 currentRefString,
                 rewrittenRefString,
                 prefix,
-                registry);
+                location);
         return ContainerRef.parse(rewrittenRefString);
     }
 
@@ -248,14 +270,25 @@ private boolean matches(ContainerRef ref, @Nullable String prefix) {
 
         // No path restriction → host-only match
         if (p.path().isEmpty()) {
+            LOG.debug("Found registry table '{}'", p);
             return true;
         }
 
         // Path prefix match (namespace/repo)
         String refPath = String.join("/", ref.getNamespace()) + "/" + ref.getRepository();
-        return refPath.equals(p.path()) || refPath.startsWith(p.path() + "/");
+        boolean result = refPath.equals(p.path()) || refPath.startsWith(p.path() + "/");
+        if (result) {
+            LOG.debug("Found registry table '{}' matching path '{}'", p, refPath);
+        }
+        return result;
     }
 
+    /**
+     * Check if the given host matches the specified prefix host, which can be a specific hostname or a wildcard pattern (e.g., *.example.com).
+     * @param host the host to check for a match against the prefix host, which is the host component of the prefix.
+     * @param prefixHost the prefix host to match against, which can be a specific hostname or a wildcard pattern (e.g., *.example.com).
+     * @return true if the host matches the prefix host, false otherwise.
+     */
     private boolean hostMatches(String host, String prefixHost) {
         if (prefixHost.startsWith("*.")) {
             String domain = prefixHost.substring(2);

src/test/java/land/oras/ContainerRefTest.java

@@ -27,7 +27,6 @@
 import land.oras.exception.OrasException;
 import land.oras.utils.SupportedAlgorithm;
 import org.junit.jupiter.api.BeforeAll;
-import org.junit.jupiter.api.Disabled;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.io.TempDir;
 import org.junit.jupiter.api.parallel.Execution;
@@ -136,7 +135,6 @@ void shouldDetermineFromAlias() throws Exception {
     }
 
     @Test
-    @Disabled("Not implemented yet")
     void shouldRewriteAllSubdomainToLocalProxy() throws Exception {
 
         // language=toml
@@ -145,6 +143,10 @@ void shouldRewriteAllSubdomainToLocalProxy() throws Exception {
                 [[registry]]
                 prefix = "*.example.com"
                 location = "localhost:5000/example-com"
+
+                [[registry]]
+                prefix = "*.otherexample.io/library"
+                location = "localhost:5001/docker"
                 """;
 
         Files.writeString(homeDir3.resolve(".config").resolve("containers").resolve("registries.conf"), config);
@@ -153,8 +155,30 @@ void shouldRewriteAllSubdomainToLocalProxy() throws Exception {
                 .set("HOME", homeDir3.toAbsolutePath().toString())
                 .execute(() -> {
                     Registry registry = Registry.builder().defaults().build();
+
+                    // One subdomain
                     ContainerRef containerRef = ContainerRef.parse("toto.example.com/library/alpine:latest");
                     assertEquals("localhost:5000", containerRef.getEffectiveRegistry(registry));
+                    ContainerRef newRef = registry.getRegistriesConf().rewrite(containerRef);
+                    assertEquals("localhost:5000/example-com/library/alpine:latest", newRef.toString());
+
+                    // Several subdomain
+                    containerRef = ContainerRef.parse("test.foobar.example.com/library/alpine:latest");
+                    assertEquals("localhost:5000", containerRef.getEffectiveRegistry(registry));
+                    newRef = registry.getRegistriesConf().rewrite(containerRef);
+                    assertEquals("localhost:5000/example-com/library/alpine:latest", newRef.toString());
+
+                    // With path
+                    containerRef = ContainerRef.parse("test.otherexample.io/library/alpine:latest");
+                    assertEquals("localhost:5001", containerRef.getEffectiveRegistry(registry));
+                    newRef = registry.getRegistriesConf().rewrite(containerRef);
+                    assertEquals("localhost:5001/docker/alpine:latest", newRef.toString());
+
+                    // No rewrite if library does not match
+                    containerRef = ContainerRef.parse("test.otherexample.io/foobar/alpine:latest");
+                    assertEquals("test.otherexample.io", containerRef.getEffectiveRegistry(registry));
+                    newRef = registry.getRegistriesConf().rewrite(containerRef);
+                    assertEquals("test.otherexample.io/foobar/alpine:latest", newRef.toString());
                 });
     }