SQL: fix URI path being lost in case of hosted ES scenario (#44776)

(cherry picked from commit 06dea859e8fddada868941aaae15e83b4f64babe)

x-pack/plugin/sql/sql-client/src/main/java/org/elasticsearch/xpack/sql/client/JreHttpUrlConnection.java

@@ -35,6 +35,7 @@ import javax.net.ssl.SSLSocketFactory;
 import javax.sql.rowset.serial.SerialException;
 
 import static java.util.Collections.emptyMap;
+import static org.elasticsearch.xpack.sql.client.UriUtils.appendSegmentToPath;
 import static org.elasticsearch.xpack.sql.proto.Protocol.SQL_QUERY_REST_ENDPOINT;
 
 /**
@@ -52,7 +53,7 @@ public class JreHttpUrlConnection implements Closeable {
             + "?error_trace] and method [POST], allowed:";
 
     public static <R> R http(String path, String query, ConnectionConfiguration cfg, Function<JreHttpUrlConnection, R> handler) {
-        final URI uriPath = cfg.baseUri().resolve(path);  // update path if needed
+        final URI uriPath = appendSegmentToPath(cfg.baseUri(), path);  // update path if needed
         final String uriQuery = query == null ? uriPath.getQuery() : query; // update query if needed
         final URL url;
         try {

x-pack/plugin/sql/sql-client/src/main/java/org/elasticsearch/xpack/sql/client/UriUtils.java

@@ -76,4 +76,33 @@ public final class UriUtils {
             throw new IllegalArgumentException("Invalid connection configuration [" + connectionString + "]: " + e.getMessage(), e);
         }
     }
+
+    public static URI appendSegmentToPath(URI uri, String segment) {
+        if (uri == null) {
+            throw new IllegalArgumentException("URI must not be null");
+        }
+        if (segment == null || segment.isEmpty() || "/".equals(segment)) {
+            return uri;
+        }
+        
+        String path = uri.getPath();
+        String concatenatedPath = "";
+        String cleanSegment = segment.startsWith("/") ? segment.substring(1) : segment;
+        
+        if (path == null || path.isEmpty()) {
+            path = "/";
+        }
+
+        if (path.charAt(path.length() - 1) == '/') {
+            concatenatedPath = path + cleanSegment;
+        } else {
+            concatenatedPath = path + "/" + cleanSegment;
+        }
+        try {
+            return new URI(uri.getScheme(), uri.getUserInfo(), uri.getHost(), uri.getPort(), concatenatedPath,
+                    uri.getQuery(), uri.getFragment());
+        } catch (URISyntaxException e) {
+            throw new IllegalArgumentException("Invalid segment [" + segment + "] for URI [" + uri + "]: " + e.getMessage(), e);
+        }
+    }
 }

x-pack/plugin/sql/sql-client/src/test/java/org/elasticsearch/xpack/sql/client/UriUtilsTests.java

@@ -9,6 +9,7 @@ import org.elasticsearch.test.ESTestCase;
 
 import java.net.URI;
 
+import static org.elasticsearch.xpack.sql.client.UriUtils.appendSegmentToPath;
 import static org.elasticsearch.xpack.sql.client.UriUtils.parseURI;
 import static org.elasticsearch.xpack.sql.client.UriUtils.removeQuery;
 
@@ -84,4 +85,56 @@ public class UriUtilsTests extends ESTestCase {
         assertEquals(URI.create("http://server:9100"),
                 removeQuery(URI.create("http://server:9100"), "http://server:9100", DEFAULT_URI));
     }
+    
+    public void testAppendEmptySegmentToPath() throws Exception {
+        assertEquals(URI.create("http://server:9100"),
+                appendSegmentToPath(URI.create("http://server:9100"), ""));
+    }
+    
+    public void testAppendNullSegmentToPath() throws Exception {
+        assertEquals(URI.create("http://server:9100"),
+                appendSegmentToPath(URI.create("http://server:9100"), null));
+    }
+    
+    public void testAppendSegmentToNullPath() throws Exception {
+        assertEquals(
+                "URI must not be null",
+                expectThrows(IllegalArgumentException.class, () -> appendSegmentToPath(null, "/_sql")).getMessage()
+        );
+    }
+    
+    public void testAppendSegmentToEmptyPath() throws Exception {
+        assertEquals(URI.create("/_sql"),
+                appendSegmentToPath(URI.create(""), "/_sql"));
+    }
+    
+    public void testAppendSlashSegmentToPath() throws Exception {
+        assertEquals(URI.create("http://server:9100"),
+                appendSegmentToPath(URI.create("http://server:9100"), "/"));
+    }
+    
+    public void testAppendSqlSegmentToPath() throws Exception {
+        assertEquals(URI.create("http://server:9100/_sql"),
+                appendSegmentToPath(URI.create("http://server:9100"), "/_sql"));
+    }
+    
+    public void testAppendSqlSegmentNoSlashToPath() throws Exception {
+        assertEquals(URI.create("http://server:9100/_sql"),
+                appendSegmentToPath(URI.create("http://server:9100"), "_sql"));
+    }
+    
+    public void testAppendSegmentToPath() throws Exception {
+        assertEquals(URI.create("http://server:9100/es_rest/_sql"),
+                appendSegmentToPath(URI.create("http://server:9100/es_rest"), "/_sql"));
+    }
+    
+    public void testAppendSegmentNoSlashToPath() throws Exception {
+        assertEquals(URI.create("http://server:9100/es_rest/_sql"),
+                appendSegmentToPath(URI.create("http://server:9100/es_rest"), "_sql"));
+    }
+    
+    public void testAppendSegmentTwoSlashesToPath() throws Exception {
+        assertEquals(URI.create("https://server:9100/es_rest/_sql"),
+                appendSegmentToPath(URI.create("https://server:9100/es_rest/"), "/_sql"));
+    }
 }