fix: respect NVD error message for resultsPerPage (#195)

resolves jeremylong/DependencyCheck#6834

open-vulnerability-clients/src/main/java/io/github/jeremylong/openvulnerability/client/nvd/NvdCveClient.java

@@ -391,6 +391,7 @@ private Collection<DefCveItem> _next(int retryCount) {
                     }
                     LOG.debug("Response: {}", new String(response.getBodyBytes(), StandardCharsets.UTF_8));
                     if (msg != null) {
+                        msg = msg.trim();
                         if (msg.contains("Invalid apiKey")) {
                             if (this.apiKey.length() > 30) {
                                 String masked = String.format("Invalid API Key: %s-*****-%s",
@@ -400,6 +401,11 @@ private Collection<DefCveItem> _next(int retryCount) {
                             }
                             String masked = String.format("Invalid API Key: %s-*****", this.apiKey.substring(0, 5));
                             throw new NvdApiException(masked);
+                        } else if (msg.startsWith("resultsPerPage parameter cannot exceed")) {
+                            this.resultsPerPage = parseResultsPerPage(msg);
+                            LOG.warn(msg);
+                            LOG.warn("NVD requested a lower resultsPerPage; settings to {}", this.resultsPerPage);
+                            return _next(retryCount + 1);
                         }
                         throw new NvdApiException("NVD Returned Status Code: " + lastStatusCode + " - " + msg);
                     }
@@ -421,6 +427,25 @@ private Collection<DefCveItem> _next(int retryCount) {
         return null;
     }
 
+    /**
+     * Attempts to parse the resultsPerPage error message to determine the maximum number of results per page.
+     * @param msg the error message from the NVD
+     * @return the parsed results per page if succesful; otherwise the previously confiuged results per page
+     */
+    protected int parseResultsPerPage(String msg) {
+        String value = msg;
+        if (value.endsWith(".")) {
+            value = value.substring(0, value.length() - 1);
+        }
+        value = value.substring(msg.lastIndexOf(" ") + 1);
+        try {
+            return Integer.parseInt(value);
+        } catch (NumberFormatException e) {
+            LOG.debug("Error parsing " + msg, e);
+        }
+        return resultsPerPage;
+    }
+
     /**
      * Retrieve the latest last updated date from the list of vulnerabilities.
      *

open-vulnerability-clients/src/test/java/io/github/jeremylong/openvulnerability/client/nvd/NvdCveClientTest.java

@@ -0,0 +1,41 @@
+/*
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ * Copyright (c) 2022-2024 Jeremy Long. All Rights Reserved.
+ */
+package io.github.jeremylong.openvulnerability.client.nvd;
+
+import org.junit.jupiter.api.Assumptions;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.Timeout;
+
+import java.time.ZoneOffset;
+import java.time.ZonedDateTime;
+import java.util.Collection;
+import java.util.concurrent.TimeUnit;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+class NvdCveClientTest {
+
+    @Test
+    public void parseResultsPerPageTest() {
+        NvdCveClient client = new NvdCveClient(null, null, 1, 1);
+        client.setResultsPerPage(2000);
+        int recordsPerPage = client.parseResultsPerPage("resultsPerPage parameter cannot exceed 1000.");
+        assertEquals(1000, recordsPerPage, "Incorrect records per page value parsed");
+    }
+}