/*
* Copyright (C) 2010 The Android Open Source Project
*
* 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.
*/
package com.squareup.okhttp;
import com.squareup.okhttp.internal.Base64;
import com.squareup.okhttp.internal.DiskLruCache;
import com.squareup.okhttp.internal.StrictLineReader;
import com.squareup.okhttp.internal.Util;
import com.squareup.okhttp.internal.http.HttpEngine;
import com.squareup.okhttp.internal.http.HttpURLConnectionImpl;
import com.squareup.okhttp.internal.http.HttpsEngine;
import com.squareup.okhttp.internal.http.HttpsURLConnectionImpl;
import com.squareup.okhttp.internal.http.RawHeaders;
import com.squareup.okhttp.internal.http.ResponseHeaders;
import java.io.BufferedWriter;
import java.io.ByteArrayInputStream;
import java.io.File;
import java.io.FilterInputStream;
import java.io.FilterOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.Writer;
import java.net.CacheRequest;
import java.net.CacheResponse;
import java.net.HttpURLConnection;
import java.net.ResponseCache;
import java.net.SecureCacheResponse;
import java.net.URI;
import java.net.URLConnection;
import java.security.Principal;
import java.security.cert.Certificate;
import java.security.cert.CertificateEncodingException;
import java.security.cert.CertificateException;
import java.security.cert.CertificateFactory;
import java.security.cert.X509Certificate;
import java.util.Arrays;
import java.util.List;
import java.util.Map;
import javax.net.ssl.SSLPeerUnverifiedException;
import javax.net.ssl.SSLSocket;
import static com.squareup.okhttp.internal.Util.US_ASCII;
import static com.squareup.okhttp.internal.Util.UTF_8;
/**
* Caches HTTP and HTTPS responses to the filesystem so they may be reused,
* saving time and bandwidth.
*
* <h3>Cache Optimization</h3>
* To measure cache effectiveness, this class tracks three statistics:
* <ul>
* <li><strong>{@link #getRequestCount() Request Count:}</strong> the number
* of HTTP requests issued since this cache was created.
* <li><strong>{@link #getNetworkCount() Network Count:}</strong> the
* number of those requests that required network use.
* <li><strong>{@link #getHitCount() Hit Count:}</strong> the number of
* those requests whose responses were served by the cache.
* </ul>
* Sometimes a request will result in a conditional cache hit. If the cache
* contains a stale copy of the response, the client will issue a conditional
* {@code GET}. The server will then send either the updated response if it has
* changed, or a short 'not modified' response if the client's copy is still
* valid. Such responses increment both the network count and hit count.
*
* <p>The best way to improve the cache hit rate is by configuring the web
* server to return cacheable responses. Although this client honors all <a
* href="http://www.ietf.org/rfc/rfc2616.txt">HTTP/1.1 (RFC 2068)</a> cache
* headers, it doesn't cache partial responses.
*
* <h3>Force a Network Response</h3>
* In some situations, such as after a user clicks a 'refresh' button, it may be
* necessary to skip the cache, and fetch data directly from the server. To force
* a full refresh, add the {@code no-cache} directive: <pre> {@code
* connection.addRequestProperty("Cache-Control", "no-cache");
* }</pre>
* If it is only necessary to force a cached response to be validated by the
* server, use the more efficient {@code max-age=0} instead: <pre> {@code
* connection.addRequestProperty("Cache-Control", "max-age=0");
* }</pre>
*
* <h3>Force a Cache Response</h3>
* Sometimes you'll want to show resources if they are available immediately,
* but not otherwise. This can be used so your application can show
* <i>something</i> while waiting for the latest data to be downloaded. To
* restrict a request to locally-cached resources, add the {@code
* only-if-cached} directive: <pre> {@code
* try {
* connection.addRequestProperty("Cache-Control", "only-if-cached");
* InputStream cached = connection.getInputStream();
* // the resource was cached! show it
* } catch (FileNotFoundException e) {
* // the resource was not cached
* }
* }</pre>
* This technique works even better in situations where a stale response is
* better than no response. To permit stale cached responses, use the {@code
* max-stale} directive with the maximum staleness in seconds: <pre> {@code
* int maxStale = 60 * 60 * 24 * 28; // tolerate 4-weeks stale
* connection.addRequestProperty("Cache-Control", "max-stale=" + maxStale);
* }</pre>
*/
public final class HttpResponseCache extends ResponseCache {
// TODO: add APIs to iterate the cache?
private static final int VERSION = 201105;
private static final int ENTRY_METADATA = 0;
private static final int ENTRY_BODY = 1;
private static final int ENTRY_COUNT = 2;
private final DiskLruCache cache;
/* read and write statistics, all guarded by 'this' */
private int writeSuccessCount;
private int writeAbortCount;
private int networkCount;
private int hitCount;
private int requestCount;
/**
* Although this class only exposes the limited ResponseCache API, it
* implements the full OkResponseCache interface. This field is used as a
* package private handle to the complete implementation. It delegates to
* public and private members of this type.
*/
final OkResponseCache okResponseCache = new OkResponseCache() {
@Override public CacheResponse get(URI uri, String requestMethod,
Map<String, List<String>> requestHeaders) throws IOException {
return HttpResponseCache.this.get(uri, requestMethod, requestHeaders);
}
@Override public CacheRequest put(URI uri, URLConnection connection) throws IOException {
return HttpResponseCache.this.put(uri, connection);
}
@Override public void maybeRemove(String requestMethod, URI uri) throws IOException {
HttpResponseCache.this.maybeRemove(requestMethod, uri);
}
@Override public void update(
CacheResponse conditionalCacheHit, HttpURLConnection connection) throws IOException {
HttpResponseCache.this.update(conditionalCacheHit, connection);
}
@Override public void trackConditionalCacheHit() {
HttpResponseCache.this.trackConditionalCacheHit();
}
@Override public void trackResponse(ResponseSource source) {
HttpResponseCache.this.trackResponse(source);
}
};
public HttpResponseCache(File directory, long maxSize) throws IOException {
cache = DiskLruCache.open(directory, VERSION, ENTRY_COUNT, maxSize);
}
private String uriToKey(URI uri) {
return Util.hash(uri.toString());
}
@Override public CacheResponse get(URI uri, String requestMethod,
Map<String, List<String>> requestHeaders) {
String key = uriToKey(uri);
DiskLruCache.Snapshot snapshot;
Entry entry;
try {
snapshot = cache.get(key);
if (snapshot == null) {
return null;
}
entry = new Entry(snapshot.getInputStream(ENTRY_METADATA));
} catch (IOException e) {
// Give up because the cache cannot be read.
return null;
}
if (!entry.matches(uri, requestMethod, requestHeaders)) {
snapshot.close();
return null;
}
return entry.isHttps() ? new EntrySecureCacheResponse(entry, snapshot)
: new EntryCacheResponse(entry, snapshot);
}
@Override public CacheRequest put(URI uri, URLConnection urlConnection) throws IOException {
if (!(urlConnection instanceof HttpURLConnection)) {
return null;
}
HttpURLConnection httpConnection = (HttpURLConnection) urlConnection;
String requestMethod = httpConnection.getRequestMethod();
if (maybeRemove(requestMethod, uri)) {
return null;
}
if (!requestMethod.equals("GET")) {
// Don't cache non-GET responses. We're technically allowed to cache
// HEAD requests and some POST requests, but the complexity of doing
// so is high and the benefit is low.
return null;
}
HttpEngine httpEngine = getHttpEngine(httpConnection);
if (httpEngine == null) {
// Don't cache unless the HTTP implementation is ours.
return null;
}
ResponseHeaders response = httpEngine.getResponseHeaders();
if (response.hasVaryAll()) {
return null;
}
RawHeaders varyHeaders =
httpEngine.getRequestHeaders().getHeaders().getAll(response.getVaryFields());
Entry entry = new Entry(uri, varyHeaders, httpConnection);
DiskLruCache.Editor editor = null;
try {
editor = cache.edit(uriToKey(uri));
if (editor == null) {
return null;
}
entry.writeTo(editor);
return new CacheRequestImpl(editor);
} catch (IOException e) {
abortQuietly(editor);
return null;
}
}
/**
* Returns true if the supplied {@code requestMethod} potentially invalidates an entry in the
* cache.
*/
private boolean maybeRemove(String requestMethod, URI uri) {
if (requestMethod.equals("POST") || requestMethod.equals("PUT") || requestMethod.equals(
"DELETE")) {
try {
cache.remove(uriToKey(uri));
} catch (IOException ignored) {
// The cache cannot be written.
}
return true;
}
return false;
}
private void update(CacheResponse conditionalCacheHit, HttpURLConnection httpConnection)
throws IOException {
HttpEngine httpEngine = getHttpEngine(httpConnection);
URI uri = httpEngine.getUri();
ResponseHeaders response = httpEngine.getResponseHeaders();
RawHeaders varyHeaders =
httpEngine.getRequestHeaders().getHeaders().getAll(response.getVaryFields());
Entry entry = new Entry(uri, varyHeaders, httpConnection);
DiskLruCache.Snapshot snapshot = (conditionalCacheHit instanceof EntryCacheResponse)
? ((EntryCacheResponse) conditionalCacheHit).snapshot
: ((EntrySecureCacheResponse) conditionalCacheHit).snapshot;
DiskLruCache.Editor editor = null;
try {
editor = snapshot.edit(); // returns null if snapshot is not current
if (editor != null) {
entry.writeTo(editor);
editor.commit();
}
} catch (IOException e) {
abortQuietly(editor);
}
}
private void abortQuietly(DiskLruCache.Editor editor) {
// Give up because the cache cannot be written.
try {
if (editor != null) {
editor.abort();
}
} catch (IOException ignored) {
}
}
private HttpEngine getHttpEngine(URLConnection httpConnection) {
if (httpConnection instanceof HttpURLConnectionImpl) {
return ((HttpURLConnectionImpl) httpConnection).getHttpEngine();
} else if (httpConnection instanceof HttpsURLConnectionImpl) {
return ((HttpsURLConnectionImpl) httpConnection).getHttpEngine();
} else {
return null;
}
}
/**
* Closes the cache and deletes all of its stored values. This will delete
* all files in the cache directory including files that weren't created by
* the cache.
*/
public void delete() throws IOException {
cache.delete();
}
public synchronized int getWriteAbortCount() {
return writeAbortCount;
}
public synchronized int getWriteSuccessCount() {
return writeSuccessCount;
}
public long getSize() {
return cache.size();
}
public long getMaxSize() {
return cache.getMaxSize();
}
public void flush() throws IOException {
cache.flush();
}
public void close() throws IOException {
cache.close();
}
public File getDirectory() {
return cache.getDirectory();
}
public boolean isClosed() {
return cache.isClosed();
}
private synchronized void trackResponse(ResponseSource source) {
requestCount++;
switch (source) {
case CACHE:
hitCount++;
break;
case CONDITIONAL_CACHE:
case NETWORK:
networkCount++;
break;
}
}
private synchronized void trackConditionalCacheHit() {
hitCount++;
}
public synchronized int getNetworkCount() {
return networkCount;
}
public synchronized int getHitCount() {
return hitCount;
}
public synchronized int getRequestCount() {
return requestCount;
}
private final class CacheRequestImpl extends CacheRequest {
private final DiskLruCache.Editor editor;
private OutputStream cacheOut;
private boolean done;
private OutputStream body;
public CacheRequestImpl(final DiskLruCache.Editor editor) throws IOException {
this.editor = editor;
this.cacheOut = editor.newOutputStream(ENTRY_BODY);
this.body = new FilterOutputStream(cacheOut) {
@Override public void close() throws IOException {
synchronized (HttpResponseCache.this) {
if (done) {
return;
}
done = true;
writeSuccessCount++;
}
super.close();
editor.commit();
}
@Override public void write(byte[] buffer, int offset, int length) throws IOException {
// Since we don't override "write(int oneByte)", we can write directly to "out"
// and avoid the inefficient implementation from the FilterOutputStream.
out.write(buffer, offset, length);
}
};
}
@Override public void abort() {
synchronized (HttpResponseCache.this) {
if (done) {
return;
}
done = true;
writeAbortCount++;
}
Util.closeQuietly(cacheOut);
try {
editor.abort();
} catch (IOException ignored) {
}
}
@Override public OutputStream getBody() throws IOException {
return body;
}
}
private static final class Entry {
private final String uri;
private final RawHeaders varyHeaders;
private final String requestMethod;
private final RawHeaders responseHeaders;
private final String cipherSuite;
private final Certificate[] peerCertificates;
private final Certificate[] localCertificates;
/**
* Reads an entry from an input stream. A typical entry looks like this:
* <pre>{@code
* http://google.com/foo
* GET
* 2
* Accept-Language: fr-CA
* Accept-Charset: UTF-8
* HTTP/1.1 200 OK
* 3
* Content-Type: image/png
* Content-Length: 100
* Cache-Control: max-age=600
* }</pre>
*
* <p>A typical HTTPS file looks like this:
* <pre>{@code
* https://google.com/foo
* GET
* 2
* Accept-Language: fr-CA
* Accept-Charset: UTF-8
* HTTP/1.1 200 OK
* 3
* Content-Type: image/png
* Content-Length: 100
* Cache-Control: max-age=600
*
* AES_256_WITH_MD5
* 2
* base64-encoded peerCertificate[0]
* base64-encoded peerCertificate[1]
* -1
* }</pre>
* The file is newline separated. The first two lines are the URL and
* the request method. Next is the number of HTTP Vary request header
* lines, followed by those lines.
*
* <p>Next is the response status line, followed by the number of HTTP
* response header lines, followed by those lines.
*
* <p>HTTPS responses also contain SSL session information. This begins
* with a blank line, and then a line containing the cipher suite. Next
* is the length of the peer certificate chain. These certificates are
* base64-encoded and appear each on their own line. The next line
* contains the length of the local certificate chain. These
* certificates are also base64-encoded and appear each on their own
* line. A length of -1 is used to encode a null array.
*/
public Entry(InputStream in) throws IOException {
try {
StrictLineReader reader = new StrictLineReader(in, US_ASCII);
uri = reader.readLine();
requestMethod = reader.readLine();
varyHeaders = new RawHeaders();
int varyRequestHeaderLineCount = reader.readInt();
for (int i = 0; i < varyRequestHeaderLineCount; i++) {
varyHeaders.addLine(reader.readLine());
}
responseHeaders = new RawHeaders();
responseHeaders.setStatusLine(reader.readLine());
int responseHeaderLineCount = reader.readInt();
for (int i = 0; i < responseHeaderLineCount; i++) {
responseHeaders.addLine(reader.readLine());
}
if (isHttps()) {
String blank = reader.readLine();
if (blank.length() > 0) {
throw new IOException("expected \"\" but was \"" + blank + "\"");
}
cipherSuite = reader.readLine();
peerCertificates = readCertArray(reader);
localCertificates = readCertArray(reader);
} else {
cipherSuite = null;
peerCertificates = null;
localCertificates = null;
}
} finally {
in.close();
}
}
public Entry(URI uri, RawHeaders varyHeaders, HttpURLConnection httpConnection)
throws IOException {
this.uri = uri.toString();
this.varyHeaders = varyHeaders;
this.requestMethod = httpConnection.getRequestMethod();
this.responseHeaders = RawHeaders.fromMultimap(httpConnection.getHeaderFields(), true);
SSLSocket sslSocket = getSslSocket(httpConnection);
if (sslSocket != null) {
cipherSuite = sslSocket.getSession().getCipherSuite();
Certificate[] peerCertificatesNonFinal = null;
try {
peerCertificatesNonFinal = sslSocket.getSession().getPeerCertificates();
} catch (SSLPeerUnverifiedException ignored) {
}
peerCertificates = peerCertificatesNonFinal;
localCertificates = sslSocket.getSession().getLocalCertificates();
} else {
cipherSuite = null;
peerCertificates = null;
localCertificates = null;
}
}
/**
* Returns the SSL socket used by {@code httpConnection} for HTTPS, nor null
* if the connection isn't using HTTPS. Since we permit redirects across
* protocols (HTTP to HTTPS or vice versa), the implementation type of the
* connection doesn't necessarily match the implementation type of its HTTP
* engine.
*/
private SSLSocket getSslSocket(HttpURLConnection httpConnection) {
HttpEngine engine = httpConnection instanceof HttpsURLConnectionImpl
? ((HttpsURLConnectionImpl) httpConnection).getHttpEngine()
: ((HttpURLConnectionImpl) httpConnection).getHttpEngine();
return engine instanceof HttpsEngine
? ((HttpsEngine) engine).getSslSocket()
: null;
}
public void writeTo(DiskLruCache.Editor editor) throws IOException {
OutputStream out = editor.newOutputStream(ENTRY_METADATA);
Writer writer = new BufferedWriter(new OutputStreamWriter(out, UTF_8));
writer.write(uri + '\n');
writer.write(requestMethod + '\n');
writer.write(Integer.toString(varyHeaders.length()) + '\n');
for (int i = 0; i < varyHeaders.length(); i++) {
writer.write(varyHeaders.getFieldName(i) + ": " + varyHeaders.getValue(i) + '\n');
}
writer.write(responseHeaders.getStatusLine() + '\n');
writer.write(Integer.toString(responseHeaders.length()) + '\n');
for (int i = 0; i < responseHeaders.length(); i++) {
writer.write(responseHeaders.getFieldName(i) + ": " + responseHeaders.getValue(i) + '\n');
}
if (isHttps()) {
writer.write('\n');
writer.write(cipherSuite + '\n');
writeCertArray(writer, peerCertificates);
writeCertArray(writer, localCertificates);
}
writer.close();
}
private boolean isHttps() {
return uri.startsWith("https://");
}
private Certificate[] readCertArray(StrictLineReader reader) throws IOException {
int length = reader.readInt();
if (length == -1) {
return null;
}
try {
CertificateFactory certificateFactory = CertificateFactory.getInstance("X.509");
Certificate[] result = new Certificate[length];
for (int i = 0; i < result.length; i++) {
String line = reader.readLine();
byte[] bytes = Base64.decode(line.getBytes("US-ASCII"));
result[i] = certificateFactory.generateCertificate(new ByteArrayInputStream(bytes));
}
return result;
} catch (CertificateException e) {
throw new IOException(e.getMessage());
}
}
private void writeCertArray(Writer writer, Certificate[] certificates) throws IOException {
if (certificates == null) {
writer.write("-1\n");
return;
}
try {
writer.write(Integer.toString(certificates.length) + '\n');
for (Certificate certificate : certificates) {
byte[] bytes = certificate.getEncoded();
String line = Base64.encode(bytes);
writer.write(line + '\n');
}
} catch (CertificateEncodingException e) {
throw new IOException(e.getMessage());
}
}
public boolean matches(URI uri, String requestMethod,
Map<String, List<String>> requestHeaders) {
return this.uri.equals(uri.toString())
&& this.requestMethod.equals(requestMethod)
&& new ResponseHeaders(uri, responseHeaders).varyMatches(varyHeaders.toMultimap(false),
requestHeaders);
}
}
/**
* Returns an input stream that reads the body of a snapshot, closing the
* snapshot when the stream is closed.
*/
private static InputStream newBodyInputStream(final DiskLruCache.Snapshot snapshot) {
return new FilterInputStream(snapshot.getInputStream(ENTRY_BODY)) {
@Override public void close() throws IOException {
snapshot.close();
super.close();
}
};
}
static class EntryCacheResponse extends CacheResponse {
private final Entry entry;
private final DiskLruCache.Snapshot snapshot;
private final InputStream in;
public EntryCacheResponse(Entry entry, DiskLruCache.Snapshot snapshot) {
this.entry = entry;
this.snapshot = snapshot;
this.in = newBodyInputStream(snapshot);
}
@Override public Map<String, List<String>> getHeaders() {
return entry.responseHeaders.toMultimap(true);
}
@Override public InputStream getBody() {
return in;
}
}
static class EntrySecureCacheResponse extends SecureCacheResponse {
private final Entry entry;
private final DiskLruCache.Snapshot snapshot;
private final InputStream in;
public EntrySecureCacheResponse(Entry entry, DiskLruCache.Snapshot snapshot) {
this.entry = entry;
this.snapshot = snapshot;
this.in = newBodyInputStream(snapshot);
}
@Override public Map<String, List<String>> getHeaders() {
return entry.responseHeaders.toMultimap(true);
}
@Override public InputStream getBody() {
return in;
}
@Override public String getCipherSuite() {
return entry.cipherSuite;
}
@Override public List<Certificate> getServerCertificateChain()
throws SSLPeerUnverifiedException {
if (entry.peerCertificates == null || entry.peerCertificates.length == 0) {
throw new SSLPeerUnverifiedException(null);
}
return Arrays.asList(entry.peerCertificates.clone());
}
@Override public Principal getPeerPrincipal() throws SSLPeerUnverifiedException {
if (entry.peerCertificates == null || entry.peerCertificates.length == 0) {
throw new SSLPeerUnverifiedException(null);
}
return ((X509Certificate) entry.peerCertificates[0]).getSubjectX500Principal();
}
@Override public List<Certificate> getLocalCertificateChain() {
if (entry.localCertificates == null || entry.localCertificates.length == 0) {
return null;
}
return Arrays.asList(entry.localCertificates.clone());
}
@Override public Principal getLocalPrincipal() {
if (entry.localCertificates == null || entry.localCertificates.length == 0) {
return null;
}
return ((X509Certificate) entry.localCertificates[0]).getSubjectX500Principal();
}
}
}