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package eu.dnetlib.data.collector.plugins.oai.engine;
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import java.io.IOException;
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import java.io.InputStream;
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import java.net.CookieHandler;
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import java.net.CookieManager;
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import java.net.CookiePolicy;
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import java.net.HttpURLConnection;
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import java.net.URL;
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import java.security.GeneralSecurityException;
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import java.security.KeyManagementException;
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import java.security.NoSuchAlgorithmException;
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import java.security.cert.CertificateException;
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import java.security.cert.X509Certificate;
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import java.util.List;
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import java.util.Map;
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import javax.net.ssl.HttpsURLConnection;
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import javax.net.ssl.SSLContext;
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import javax.net.ssl.TrustManager;
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import javax.net.ssl.X509TrustManager;
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import org.apache.commons.io.IOUtils;
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import org.apache.commons.lang.math.NumberUtils;
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import org.apache.commons.logging.Log;
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import org.apache.commons.logging.LogFactory;
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import eu.dnetlib.data.collector.plugin.CollectorPluginErrorLogList;
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import eu.dnetlib.data.collector.rmi.CollectorServiceException;
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/**
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* @author jochen, michele, andrea
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*
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*/
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public class HttpConnector {
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private static final Log log = LogFactory.getLog(HttpConnector.class);
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private int maxNumberOfRetry = 6;
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private int defaultDelay = 120; // seconds
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private int readTimeOut = 120; // seconds
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private String userAgent = "Mozilla/5.0 (compatible; OAI; +http://www.openaire.eu)";
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public HttpConnector(){
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CookieHandler.setDefault(new CookieManager(null, CookiePolicy.ACCEPT_ALL));
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}
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/**
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* @param requestUrl
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* @return the content of the downloaded resource
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* @throws CollectorServiceException
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*/
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public String getInputSource(final String requestUrl) throws CollectorServiceException {
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return attemptDownload(requestUrl, 1, new CollectorPluginErrorLogList());
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}
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private String attemptDownload(final String requestUrl, final int retryNumber, final CollectorPluginErrorLogList errorList)
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throws CollectorServiceException {
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if (retryNumber > maxNumberOfRetry) { throw new CollectorServiceException("Max number of retries exceeded. Cause: \n " + errorList); }
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log.debug("Downloading " + requestUrl + " - try: " + retryNumber);
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try {
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InputStream input = null;
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try {
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final HttpURLConnection urlConn = (HttpURLConnection) new URL(requestUrl).openConnection();
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urlConn.setInstanceFollowRedirects(false);
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urlConn.setReadTimeout(readTimeOut * 1000);
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urlConn.addRequestProperty("User-Agent", userAgent);
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if (log.isDebugEnabled()) {
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logHeaderFields(urlConn);
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}
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int retryAfter = obtainRetryAfter(urlConn.getHeaderFields());
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if (retryAfter > 0) {
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log.warn("waiting and repeating request after " + retryAfter + " sec.");
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Thread.sleep(retryAfter * 1000);
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errorList.add("503 Service Unavailable");
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return attemptDownload(requestUrl, retryNumber + 1, errorList);
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} else if ((urlConn.getResponseCode() == HttpURLConnection.HTTP_MOVED_PERM) || (urlConn.getResponseCode() == HttpURLConnection.HTTP_MOVED_TEMP)) {
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final String newUrl = obtainNewLocation(urlConn.getHeaderFields());
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log.info("The requested url has been moved to " + newUrl);
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errorList.add(String.format("%s %s. Moved to: %s", urlConn.getResponseCode(), urlConn.getResponseMessage(), newUrl));
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return attemptDownload(newUrl, retryNumber + 1, errorList);
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} else if (urlConn.getResponseCode() != HttpURLConnection.HTTP_OK) {
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log.error(String.format("HTTP error: %s %s", urlConn.getResponseCode(), urlConn.getResponseMessage()));
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Thread.sleep(defaultDelay * 1000);
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errorList.add(String.format("%s %s", urlConn.getResponseCode(), urlConn.getResponseMessage()));
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return attemptDownload(requestUrl, retryNumber + 1, errorList);
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} else {
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input = urlConn.getInputStream();
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return IOUtils.toString(input);
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}
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} catch (IOException e) {
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log.error("error while retrieving from http-connection occured: " + e, e);
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Thread.sleep(defaultDelay * 1000);
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errorList.add(e.getMessage());
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return attemptDownload(requestUrl, retryNumber + 1, errorList);
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} finally {
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IOUtils.closeQuietly(input);
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}
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} catch (InterruptedException e) {
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throw new CollectorServiceException(e);
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}
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}
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private void logHeaderFields(final HttpURLConnection urlConn) throws IOException {
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log.debug("StatusCode: " + urlConn.getResponseMessage());
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for (Map.Entry<String, List<String>> e : urlConn.getHeaderFields().entrySet()) {
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if (e.getKey() != null) {
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for (String v : e.getValue()) {
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log.debug(" key: " + e.getKey() + " - value: " + v);
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}
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}
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}
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}
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private int obtainRetryAfter(final Map<String, List<String>> headerMap) {
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for (String key : headerMap.keySet()) {
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if ((key != null) && key.toLowerCase().equals("retry-after") && (headerMap.get(key).size() > 0) && NumberUtils.isNumber(headerMap.get(key).get(0))) { return Integer
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.parseInt(headerMap.get(key).get(0)) + 10; }
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}
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return -1;
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}
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private String obtainNewLocation(final Map<String, List<String>> headerMap) throws CollectorServiceException {
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for (String key : headerMap.keySet()) {
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if ((key != null) && key.toLowerCase().equals("location") && (headerMap.get(key).size() > 0)) { return headerMap.get(key).get(0); }
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}
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throw new CollectorServiceException("The requested url has been MOVED, but 'location' param is MISSING");
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}
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/**
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* register for https scheme; this is a workaround and not intended for the use in trusted environments
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*
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* @throws NoSuchAlgorithmException
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* @throws KeyManagementException
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*/
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public void initTrustManager() {
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final X509TrustManager tm = new X509TrustManager() {
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@Override
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public void checkClientTrusted(final X509Certificate[] xcs, final String string) throws CertificateException {}
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@Override
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public void checkServerTrusted(final X509Certificate[] xcs, final String string) throws CertificateException {}
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@Override
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public X509Certificate[] getAcceptedIssuers() {
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return null;
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}
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};
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try {
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final SSLContext ctx = SSLContext.getInstance("TLS");
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ctx.init(null, new TrustManager[] { tm }, null);
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HttpsURLConnection.setDefaultSSLSocketFactory(ctx.getSocketFactory());
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} catch (GeneralSecurityException e) {
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log.fatal(e);
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throw new IllegalStateException(e);
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}
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}
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public int getMaxNumberOfRetry() {
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return maxNumberOfRetry;
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}
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public void setMaxNumberOfRetry(final int maxNumberOfRetry) {
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this.maxNumberOfRetry = maxNumberOfRetry;
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}
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public int getDefaultDelay() {
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return defaultDelay;
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}
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public void setDefaultDelay(final int defaultDelay) {
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this.defaultDelay = defaultDelay;
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}
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public int getReadTimeOut() {
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return readTimeOut;
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}
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public void setReadTimeOut(final int readTimeOut) {
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this.readTimeOut = readTimeOut;
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}
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}
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