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Add an Error Prone check to discourage APIs that convert a hostname t…
…o a single IP address PiperOrigin-RevId: 552955605
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core/src/main/java/com/google/errorprone/bugpatterns/AddressSelection.java
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/* | ||
* Copyright 2023 The Error Prone Authors. | ||
* | ||
* 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. | ||
*/ | ||
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package com.google.errorprone.bugpatterns; | ||
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import static com.google.common.collect.Iterables.getOnlyElement; | ||
import static com.google.errorprone.BugPattern.SeverityLevel.WARNING; | ||
import static com.google.errorprone.fixes.SuggestedFixes.qualifyType; | ||
import static com.google.errorprone.fixes.SuggestedFixes.renameMethodInvocation; | ||
import static com.google.errorprone.matchers.Description.NO_MATCH; | ||
import static com.google.errorprone.matchers.method.MethodMatchers.constructor; | ||
import static com.google.errorprone.matchers.method.MethodMatchers.staticMethod; | ||
import static com.google.errorprone.util.ASTHelpers.constValue; | ||
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import com.google.common.collect.ImmutableSet; | ||
import com.google.errorprone.BugPattern; | ||
import com.google.errorprone.VisitorState; | ||
import com.google.errorprone.bugpatterns.BugChecker.MethodInvocationTreeMatcher; | ||
import com.google.errorprone.bugpatterns.BugChecker.NewClassTreeMatcher; | ||
import com.google.errorprone.fixes.SuggestedFix; | ||
import com.google.errorprone.matchers.Description; | ||
import com.google.errorprone.matchers.Matcher; | ||
import com.google.errorprone.matchers.Matchers; | ||
import com.sun.source.tree.ExpressionTree; | ||
import com.sun.source.tree.MethodInvocationTree; | ||
import com.sun.source.tree.NewClassTree; | ||
import java.util.Objects; | ||
import java.util.function.Supplier; | ||
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/** A {@link BugChecker}; see the associated {@link BugPattern} annotation for details. */ | ||
@BugPattern( | ||
summary = | ||
"Prefer InetAddress.getAllName to APIs that convert a hostname to a single IP address", | ||
severity = WARNING) | ||
public final class AddressSelection extends BugChecker | ||
implements NewClassTreeMatcher, MethodInvocationTreeMatcher { | ||
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private static final Matcher<ExpressionTree> CONSTRUCTORS = | ||
Matchers.anyOf( | ||
constructor().forClass("java.net.Socket").withParameters("java.lang.String", "int"), | ||
constructor() | ||
.forClass("java.net.InetSocketAddress") | ||
.withParameters("java.lang.String", "int")); | ||
private static final Matcher<ExpressionTree> METHODS = | ||
staticMethod() | ||
.onClass("java.net.InetAddress") | ||
.named("getByName") | ||
.withParameters("java.lang.String"); | ||
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@Override | ||
public Description matchNewClass(NewClassTree tree, VisitorState state) { | ||
if (!CONSTRUCTORS.matches(tree, state)) { | ||
return NO_MATCH; | ||
} | ||
ExpressionTree argument = tree.getArguments().get(0); | ||
return handleMatch( | ||
argument, | ||
argument, | ||
() -> { | ||
SuggestedFix.Builder fix = SuggestedFix.builder(); | ||
fix.replace( | ||
argument, qualifyType(state, fix, "java.net.InetAddress") + ".getLoopbackAddress()"); | ||
return fix.build(); | ||
}); | ||
} | ||
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@Override | ||
public Description matchMethodInvocation(MethodInvocationTree tree, VisitorState state) { | ||
if (!METHODS.matches(tree, state)) { | ||
return NO_MATCH; | ||
} | ||
ExpressionTree argument = getOnlyElement(tree.getArguments()); | ||
return handleMatch( | ||
argument, | ||
tree, | ||
() -> | ||
SuggestedFix.builder() | ||
.merge(renameMethodInvocation(tree, "getLoopbackAddress", state)) | ||
.delete(argument) | ||
.build()); | ||
} | ||
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private static final ImmutableSet<String> LOOPBACK = ImmutableSet.of("127.0.0.1", "::1"); | ||
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private Description handleMatch( | ||
ExpressionTree argument, ExpressionTree replacement, Supplier<SuggestedFix> fix) { | ||
String value = constValue(argument, String.class); | ||
if (Objects.equals(value, "localhost")) { | ||
return NO_MATCH; | ||
} | ||
Description.Builder description = buildDescription(replacement); | ||
if (LOOPBACK.contains(value)) { | ||
description.addFix(fix.get()); | ||
} | ||
return description.build(); | ||
} | ||
} |
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core/src/test/java/com/google/errorprone/bugpatterns/AddressSelectionTest.java
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/* | ||
* Copyright 2023 The Error Prone Authors. | ||
* | ||
* 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. | ||
*/ | ||
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package com.google.errorprone.bugpatterns; | ||
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import com.google.errorprone.BugCheckerRefactoringTestHelper; | ||
import com.google.errorprone.CompilationTestHelper; | ||
import org.junit.Test; | ||
import org.junit.runner.RunWith; | ||
import org.junit.runners.JUnit4; | ||
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@RunWith(JUnit4.class) | ||
public class AddressSelectionTest { | ||
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private final CompilationTestHelper compilationHelper = | ||
CompilationTestHelper.newInstance(AddressSelection.class, getClass()); | ||
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private final BugCheckerRefactoringTestHelper refactoringTestHelper = | ||
BugCheckerRefactoringTestHelper.newInstance(AddressSelection.class, getClass()); | ||
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@Test | ||
public void positive() { | ||
compilationHelper | ||
.addSourceLines( | ||
"Test.java", | ||
"import java.net.InetAddress;", | ||
"import java.net.InetSocketAddress;", | ||
"import java.net.Socket;", | ||
"class Test {", | ||
" void f() throws Exception{", | ||
" // BUG: Diagnostic contains:", | ||
" InetAddress.getByName(\"example.com\");", | ||
" // BUG: Diagnostic contains:", | ||
" new Socket(\"example.com\", 80);", | ||
" // BUG: Diagnostic contains:", | ||
" new InetSocketAddress(\"example.com\", 80);", | ||
" }", | ||
"}") | ||
.doTest(); | ||
} | ||
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@Test | ||
public void negative() throws Exception { | ||
compilationHelper | ||
.addSourceLines( | ||
"Test.java", | ||
"import java.net.InetAddress;", | ||
"import java.net.InetSocketAddress;", | ||
"import java.net.Socket;", | ||
"class Test {", | ||
" void f() throws Exception{", | ||
" new Socket(InetAddress.getLoopbackAddress(), 80);", | ||
" InetAddress.getAllByName(\"example.com\");", | ||
" new InetSocketAddress(InetAddress.getLoopbackAddress(), 80);", | ||
" }", | ||
"}") | ||
.doTest(); | ||
} | ||
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@Test | ||
public void negativeLocalhost() throws Exception { | ||
compilationHelper | ||
.addSourceLines( | ||
"Test.java", | ||
"import java.net.InetAddress;", | ||
"import java.net.InetSocketAddress;", | ||
"import java.net.Socket;", | ||
"class Test {", | ||
" void f() throws Exception{", | ||
" new Socket(\"localhost\", 80);", | ||
" InetAddress.getByName(\"localhost\");", | ||
" new InetSocketAddress(\"localhost\", 80);", | ||
" }", | ||
"}") | ||
.doTest(); | ||
} | ||
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@Test | ||
public void refactor() throws Exception { | ||
refactoringTestHelper | ||
.addInputLines( | ||
"Test.java", | ||
"import java.net.InetAddress;", | ||
"import java.net.InetSocketAddress;", | ||
"import java.net.Socket;", | ||
"class Test {", | ||
" void f() throws Exception{", | ||
" new Socket(\"127.0.0.1\", 80);", | ||
" InetAddress.getByName(\"127.0.0.1\");", | ||
" new InetSocketAddress(\"127.0.0.1\", 80);", | ||
" new Socket(\"::1\", 80);", | ||
" InetAddress.getByName(\"::1\");", | ||
" new InetSocketAddress(\"::1\", 80);", | ||
" }", | ||
"}") | ||
.addOutputLines( | ||
"Test.java", | ||
"import java.net.InetAddress;", | ||
"import java.net.InetSocketAddress;", | ||
"import java.net.Socket;", | ||
"class Test {", | ||
" void f() throws Exception{", | ||
" new Socket(InetAddress.getLoopbackAddress(), 80);", | ||
" InetAddress.getLoopbackAddress();", | ||
" new InetSocketAddress(InetAddress.getLoopbackAddress(), 80);", | ||
" new Socket(InetAddress.getLoopbackAddress(), 80);", | ||
" InetAddress.getLoopbackAddress();", | ||
" new InetSocketAddress(InetAddress.getLoopbackAddress(), 80);", | ||
" }", | ||
"}") | ||
.doTest(); | ||
} | ||
} |
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Avoid APIs that convert a hostname to a single IP address: | ||
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* [`java.net.Socket(String,int)`](https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/net/Socket.html#%3Cinit%3E\(java.lang.String,int,boolean\)) | ||
* [`java.net.InetSocketAddress(String,int)`](https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/net/InetSocketAddress.html#%3Cinit%3E\(java.lang.String,int\)) | ||
* [`java.net.InetAddress.html#getByName(String)`](https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/net/InetAddress.html#getByName\(java.lang.String\)) | ||
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Depending on the value of the | ||
[`-Djava.net.preferIPv6Addresses=true`](https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/net/doc-files/net-properties.html) | ||
system property, those APIs will return an IPv4 or IPv6 address. If a client | ||
only has IPv4 connectivity, it will fail to connect with | ||
`-Djava.net.preferIPv6Addresses=true`. If a client only has IPv6 connectivity, | ||
it will fail to connect with `-Djava.net.preferIPv6Addresses=false`. | ||
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The preferred alternative is for clients to consider all addresses returned by | ||
[`java.net.InetAddress.html#getAllByName(String)`](https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/net/InetAddress.html#getAllByName\(java.lang.String\)), | ||
and try to connect to each one until a successful connection is made. | ||
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TIP: To resolve a loopback address, prefer `InetAddress.getLoopbackAddress()` | ||
over hard-coding an IPv4 or IPv6 loopback address with | ||
`InetAddress.getByName("127.0.0.1")` or `InetAddress.getByName("::1")`. | ||
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This is, prefer this: | ||
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```java | ||
Socket doConnect(String hostname, int port) throws IOException { | ||
IOException exception = null; | ||
for (InetAddress address : InetAddress.getAllByName(hostname)) { | ||
try { | ||
return new Socket(address, port); | ||
} catch (IOException e) { | ||
if (exception == null) { | ||
exception = e; | ||
} else { | ||
exception.addSuppressed(e); | ||
} | ||
} | ||
} | ||
throw exception; | ||
} | ||
``` | ||
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```java | ||
Socket doConnect(String hostname, int port) throws IOException { | ||
IOException exception = null; | ||
for (InetAddress address : InetAddress.getAllByName(hostname)) { | ||
try { | ||
Socket s = new Socket(); | ||
s.connect(new InetSocketAddress(address, port)); | ||
return s; | ||
} catch (IOException e) { | ||
if (exception == null) { | ||
exception = e; | ||
} else { | ||
exception.addSuppressed(e); | ||
} | ||
} | ||
} | ||
throw exception; | ||
} | ||
``` | ||
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instead of this: | ||
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```java | ||
Socket doConnect(String hostname, int port) throws IOException { | ||
return new Socket(hostname, port); | ||
} | ||
``` | ||
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```java | ||
void doConnect(String hostname, int port) throws IOException { | ||
Socket s = new Socket(); | ||
s.connect(new InetSocketAddress(hostname, port)); | ||
} | ||
``` | ||
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```java | ||
void doConnect(String hostname, int port) throws IOException { | ||
Socket s = new Socket(); | ||
s.connect(new InetSocketAddress(InetAddress.getByName(hostname), port)); | ||
} | ||
``` |